KR101783813B1 - Sensor and system for detecting underground environment change using magnetic induction - Google Patents

Abstract

The present invention relates to a sensor for detecting a change in underground environment.
The sensing sensor of the present invention includes a coil part embedded in the ground and sensing an AC signal in a magnetic induction manner, a receiving part converting an AC signal sensed by the coil part into a DC signal, And a controller for measuring the amount of change in path loss of the AC signal.

Description

TECHNICAL FIELD [0001] The present invention relates to a sensor and a sensing system for detecting a change in an underground environment using magnetic induction,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sensor for detecting a change in underground environment and a sensing system using the same.

A recent report that a sinkhole occurred in a downtown area is not reported. A sinkhole sinks when a cavity underground does not withstand the weight of the ground or structure in the cavity, meaning a large hole connected to the surface.

If an underground event such as a sinkhole occurs in an upscale modern city, property damage as well as personal injury may occur.

In addition to natural phenomena, it is studied that there are artificial factors such as large-scale civil works. As a result, residents in areas where large-scale civil works are in progress often suffer from anxiety that they do not know when a sink hole will occur, resulting in a large social issue.

Therefore, there is a need for a technology to monitor the underground environment change in order to solve the public anxiety and to minimize the human and physical damage caused by the underground event.

Korean Patent Application No. 10-2013-0051175 discloses a " system for probing underground facilities by signal processing of geophysical exploration equipment ". The prior art Zircalysteographic apparatus has a miniaturized device by loading a zirconia probe on a cart and moves the miniaturized probe from the ground to detect an abnormality of the underground facility.

However, there is a spatial restriction that it is difficult to observe a wide area because an underground buried-material probe according to the prior art has to scan a cart by directly moving the worker, and there is a time constraint .

Therefore, the inventor of the present invention has studied for a long time to solve such a problem, developed through trial and error, and finally completed the present invention.

An object of the present invention is to provide a sensor and a sensing system for detecting a change in underground environment by analyzing a path loss of a signal sensed by a magnetic induction method.

Changes in the underground environment may include, but are not limited to, changes in geological conditions in the underground space, groundwater distribution and changes, changes in urban structures and surrounding grounds, including urban railways, and changes in water and wastewater conduits.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a first aspect of the present invention provides a magnetic resonance imaging apparatus comprising: a coil part for sensing an AC signal propagated through an underground in a magnetic induction manner; And a control unit for repeatedly sensing the AC signal to measure a change amount of the AC signal.

In the present invention, the coil unit may sense the AC signal in a magnetic resonance manner.

In the present invention, the coil portion may include a first coil portion and a second coil portion having an inductance greater than that of the first coil portion.

In the present invention, the coil portion may include a first coil portion and a second coil portion having a coil shape different from the first coil portion.

In the present invention, the first coil portion may be a spiral coil, and the second coil portion may include a helical coil.

In the present invention, the second coil part may interlock with at least two first coil parts to sense the AC signal.

In the present invention, it is preferable to further include a matching unit including at least one variable capacitor, and the control unit adjusts a capacitance of the variable capacitor to perform impedance matching with another underground environment change sensor.

In the present invention, it is preferable to further include a rotation unit for rotating the coil unit, and the control unit controls the rotation unit so that the coil unit directs an AC signal emission direction.

In the present invention, it is preferable that the apparatus further includes a depth adjusting unit for adjusting the depth of the coil part, and the controller controls the depth adjusting unit so that the coil unit can receive an AC signal at different depths of burial.

In the present invention, the coil portion may include at least two coils spaced apart from each other in the depth direction of the ground.

The present invention may further comprise a transmitter for generating an AC signal transmitted from the other part of the coil section through the coil section.

The present invention may further comprise a receiver for converting the AC signal sensed through the coil part into a digital signal.

In the present invention, it is preferable that the controller determines that a change in the underground environment occurs when the AC signal is out of the critical range.

A second aspect of the present invention is a method for detecting an underground environment change, comprising: a plurality of underground environment change detection sensors for repeatedly transmitting and receiving an alternating current signal propagated through the ground in a magnetic induction manner; And an underground environment change detection server for monitoring changes in the underground environment from the change of the AC signals received from the plurality of underground environment change sensors.

A third aspect of the present invention is a method for detecting an AC signal, comprising: at least one first sensing sensor for transmitting an AC signal in a magnetic induction manner; At least one second sensing sensor for sensing the AC signal propagating through the ground away from the first sensing sensor; And an underground environment change detection server for repeatedly measuring a change amount of the AC signal sensed by the second sensor and detecting a change in the underground environment.

In the present invention, the underground environment change detection server may determine that a change in the underground environment occurs when the AC signal is out of the critical range.

In the present invention, it is preferable that the underground environment change detection server warns occurrence of underground environment change when the AC signal continuously increases or decreases more than a threshold number of times.

In the present invention, the underground environment change detection server analyzes a change in path loss according to a change in a medium property on a path through which the AC signal propagates from a change in the AC signal, It is better to detect the change.

In the present invention, the underground environment change detection server may be configured to detect an underground structure change including at least one of a change in a geological condition of an underground space, a change in groundwater distribution, a water supply and drainage pipe, a gas pipe, a pipeline, an electric line, It is good to monitor at least one.

The above and other objects and features of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: FIG. Since there has been no case in which the underground environment change is detected using the path loss of a signal transmitted in a magnetic induction manner in detecting a change in the underground environment in the past, the present invention proposes a completely new underground environment change detection method .

In addition, the present invention has an effect of monitoring underground environment changes in a specific area in real time and continuously. Because the sensor is buried in the ground, it can periodically measure changes in the underground environment through the sensor. Therefore, the present invention does not need to measure the change of the underground environment by manually moving the measuring apparatus using a vehicle or the like.

In addition, the present invention has an effect of three-dimensionally detecting changes in the underground environment of a specific area. This is because the sensor of the present invention is capable of creating a three-dimensional map of changes in the underground environment because the sensor (s) are embedded in the z-axis direction as well as the x- and y-axis directions constituting the horizontal plane.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

FIG. 1 is a diagram illustrating a system for detecting change in underground environment in an embodiment of the present invention. Referring to FIG.
FIG. 2 is a view showing a sensor for detecting a change in the underground environment buried in the ground in an embodiment of the present invention. FIG.
3 is a diagram illustrating a configuration of a sensor for detecting a change in underground environment in an embodiment of the present invention.
4 is a diagram illustrating a configuration of a control unit of a subterranean environment change sensor according to an embodiment of the present invention.
5 is a diagram showing signal processing of a transmitting unit and a receiving unit in an embodiment of the present invention.
FIG. 6 is a diagram illustrating an exemplary embodiment of the present invention in which an underground environment change event is detected by analyzing a digital signal measured during a plurality of periods. FIG.
7 is a diagram for explaining a matching unit of a control unit in an embodiment of the present invention.
FIG. 8 is a flowchart showing impedance matching by the control unit according to an embodiment of the present invention. FIG.
9 is a diagram for explaining a queue factor in an embodiment according to the present invention.
10 is a diagram showing an enhancement of magnetic resonance using a second coil in an embodiment of the present invention.
Figs. 11 and 12 are diagrams showing signals exchanged between a plurality of detection sensors according to an embodiment of the present invention. Fig.
FIG. 13 is a flowchart illustrating a method of detecting a change in underground environment in an embodiment of the present invention. FIG.
* The accompanying drawings illustrate examples of the present invention in order to facilitate understanding of the technical idea of the present invention, and thus the scope of the present invention is not limited thereto.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

In the present invention, the transmission of an AC signal using magnetic induction is used to mean that an inductive coupling transmitting unit and a receiving unit transmit signals in a magnetic induction manner.

Also, in the present invention, the transmission of an AC signal using magnetic resonance is used to transmit a signal using a strong magnetic field coupling formed between resonance coils having the same resonance frequency (a transmitting portion and a receiving portion) .

Unless otherwise specifically described in the present invention, the signal sensing of the magnetic induction method is defined to include a signal sensing of a magnetic resonance method.

The present invention is to detect an underground event occurring in real time, for example, occurrence of a sinkhole, by monitoring the state of the ground routinely and periodically. As mentioned in the related art, the GPR method exposes many limitations in terms of real-time safety management because it must perform intermittent or event sensing using a separate detection means. The present inventors have derived the present invention under the concept that detection of underground events should be guaranteed in terms of periodicity, continuity and real time. As a concrete means, detection by magnetic induction method was adopted. Examples of applications of magnetic induction in the ground were limited to power and communication fields such as underground communications and power transmission. However, in this field, the transmission of signals or power by the magnetic induction method has not been activated due to the fact that the path loss can not be overcome. In other words, the most important factor in transmitting a signal or power is to minimize the amount of signal or power loss. When the signal is transmitted through the ground, the path loss is very large.

However, the weakness of the path loss in the communication field is transformed into a very useful sensing element in the field of detecting the change of the underground environment. In other words, if the medium changes, the amount of path loss changes, which can detect changes in the underground environment. Standard and abnormal conditions can be detected by changing the amount of path loss. The present invention has an important meaning in that the weakness in the field of communication has been changed to a strength of underground event detection through the reverse idea. Hereinafter, how the underground event detection through the magnetic induction method is performed will be described in detail.

FIG. 1 is a view showing a system for detecting changes in an underground environment in an embodiment of the present invention, and FIG. 2 is a view showing a sensor for detecting changes in an underground environment embedded in the ground in an embodiment of the present invention.

1 and 2, the underground environment change detection system 10 of the present invention may include a plurality of underground environment change detection sensors 100, a repeater 200, and a underground environment change detection server 300 have.

The plurality of underground environment change detection sensors 100 are spaced apart from each other to form a single sensor network. The individual sensing sensors include wired or wireless communication capabilities. Therefore, the sensor network of the present invention can be a sensor grid using the Internet of interest (IoT).

The plurality of underground environment change detection sensors 100 are disposed at predetermined intervals in the x and y axis directions constituting the horizon planes. And is buried at a predetermined depth in the depth direction z-axis direction.

In a preferred embodiment, the individual underground environment change sensor 100 may be connected to the repeater 200 in a wired or wireless manner. However, the present invention is not limited thereto. That is, in another embodiment, the individual underground environment change detection sensor 100 may be connected to the individual underground environment change detection sensors 100 in a wired or wireless manner, instead of being connected to the repeater 200. When the individual underground environment change detection sensors 100 are connected to each other, the data output from the detection sensor can be transmitted to the underground environment change detection server 300 without installing or installing the relay 200 in a small amount.

The sensing sensor 100 is embedded in the ground, and the other sensing sensor senses an AC signal generated in a magnetic induction manner. One sensing sensor 100 may sense an alternating current signal, but may also alternately emit an alternating current signal to another sensing sensor at the same time or at a time difference.

For example, the sensing sensor 100-1 of FIG. 2 transmits an AC signal to the other sensing sensor 100-2 via the coil La. The AC signal is transmitted to the other sensor 100-2 in a magnetically induced manner. The sensing sensor 100-2 senses the AC signal through the coil Lb. On the other hand, the detection sensor 100-2 can transmit an AC signal to another detection sensor 100-3 through the coil Lc. Another sensing sensor 100-3 senses the AC signal through the coil Ld.

The sensing sensor 100 can measure the path loss according to the medium characteristic of the propagation path of the AC signal from the magnitude of the sensed AC signal. The magnitude of the AC signal sensed by the sensing sensor reflects the path loss due to the medium characteristics of the AC signal propagation path. For example, the magnitude of the AC signal sensed by the sensing sensor 100-2 through the coil Lb will be different from the magnitude of the AC signal sensed by the sensing sensor 100-3 through the coil Ld. This is because the medium 1 on the propagation path of the AC signal is different. Depending on the characteristics of the medium 1, the path loss of the AC signal may increase or decrease. For example, path loss may be reduced when cavities occur, and path loss may be increased when groundwater is entrained in cavities.

The repeater 200 receives signals transmitted from the plurality of sensing sensors 100 and transmits the signals to the sensing server 300. However, if the area in which the detection sensor 100 is embedded is not wide or if the detection sensor 100 can be connected to the detection server 300 directly or wirelessly or if there is any other reason, Installation can be omitted.

The underground environment change detection server 300 analyzes the magnitude of the AC signal sensed by the plurality of detection sensors 100 and detects a change in the underground environment of the buried area.

Changes in the underground environment may include, for example, changes in geological conditions in underground spaces, changes in groundwater distribution, changes in urban structures and surrounding grounds, including urban railways, and changes in water and wastewater pipeline conditions.

Therefore, the underground environment change detection server 300 can detect the underground environment change detection server 300 when the sinkhole has occurred, the area of the aquifer has increased, the water has leaked to the water supply and drainage pipe, or the underground environment such as the gas pipe, It is possible to monitor that deformation has occurred in the structure or that the moisture content has changed in the ground of agricultural land. In addition, structural changes in hazardous facilities such as radioactive waste can be monitored.

Meanwhile, the underground environment change detection system of the present invention can be combined with various application apparatuses. For example, the underground environment change detection server can be combined with a ground sprinkler. Sprinklers on the ground are automatically notified that the water content in the ground of the agricultural land has been reduced and can start watering automatically.

As described above, the underground environment change detection system of the present invention aims at detecting and predicting anomalies in the underground space in advance.

The underground environment change detection server 300 detects a change in the underground environment in consideration of the fact that the path loss changes as the characteristics of the medium in the propagation path of the sensed AC signal change. Since the size of the sensed AC signal reflects the path loss according to the characteristics of the medium of the propagation path of the AC signal, if the magnitude of the sensed AC signal is compared at every predetermined period, have.

In the above embodiment, when the size of the AC signal is measured by the sensing sensor 100, the sensing server 300 analyzes the magnitude of the AC signal to detect the occurrence of the underground environment change. However, the embodiment of the present invention is not limited thereto no.

In another embodiment, the sensing sensor can directly determine that a change in the underground environment occurs when the magnitude of the signal exceeds the predetermined threshold range by analyzing the magnitude of the measured AC signal. In this case, the detection server 300 may receive only the event occurrence result, not the size of the AC signal sensed from the detection sensor 100.

3 is a diagram illustrating a configuration of a sensor for detecting a change in underground environment in an embodiment of the present invention.

3, in the preferred embodiment, the sensing sensor 100 may be installed in the internal space 21 of the buried hole 20 formed in the ground. The buried hole 20 includes a lower fixing part 23 for fixing the rotation part 150 of the detection sensor 100, an upper fixing part 25 for supporting the upper part of the detection sensor 100, And a top cover 29 covering the buried hole 20 so that the detection sensor 100 is not exposed.

In a preferred embodiment, the underground environment change detection sensor 100 includes an outer case 110, a coil part 120, a control part 130, a rotation part 150, and a depth control part 160.

The outer case 110 may house the coil part 120 and the control part 130 therein. The outer case 110 has a dustproof and waterproof function to protect the housed components. The outer case 110 is formed of a material that does not interfere with the transmission and reception of the AC signals in the magnetic induction manner.

The coil section 120 includes a coil capable of transmitting and sensing an AC signal. Although the coil section 120 of the present invention may include one coil, in a preferred embodiment, the coil section 120 may comprise a plurality of coils.

The coil of the present invention may include, but is not necessarily limited to, a spiral coil or a helical coil depending on the winding form of the coil.

The spiral coil may mean a coil formed in a spiral shape having a certain diameter on a virtual plane formed perpendicular to the central axis direction. The helical coil may mean a coil formed in a helical shape having a certain height along the central axis direction.

The coil part 120 of the present invention may be used in two or more types of coils at the same time. For example, a spiral coil may be used as the first coil part, and a helical coil may be used as the second coil part.

The helicon coil has a better directivity than the spiral coil, so that the loss of signal transmission is reduced.

The coil portion of the present invention may include a first coil portion and a second coil portion. The second coil portion may have an inductance greater than that of the first coil portion, or may be a coil having a different coil shape than the first coil portion. For example, the first coil portion may be a spiral coil, and the second coil portion may be a helical coil.

In one embodiment, the second coil portion may interlock with at least two first coil portions to sense or transmit a signal. For example, the first coil portion may be formed in a structure in which four first coil portions are interlocked with one second coil portion. For this, the size of the first coil part may be smaller than the size of the second coil part.

In one embodiment, the coil section 120 may include a plurality of coils spaced a predetermined distance in the depth direction (z-axis direction).

In other embodiments, the coil section 120 may include at least two coils of different magnitudes having different inductances. Increasing the Q-factor by using coils of different characteristics at the same time can enhance magnetic resonance. A detailed description thereof will be described later with reference to FIG.

The control unit 130 is disposed in an inner space (or an outer space) of the outer case 110 and is connected to the coil unit 120. The control unit 130 controls the transmission and reception of the AC signals through the coil unit 120. The specific configuration of the control unit 130 will be described later with reference to FIG.

The rotation unit 150 rotates the coil unit 120 to adjust the direction in which the coil unit 120 is oriented. By adjusting the direction in which the coil part 120 is directed, the sensing efficiency of the AC signal can be increased. The rotation unit 150 may receive control information on the amount of rotation and the rotation time from the control unit 130.

In the preferred embodiment, the rotation part 150 may be positioned at the lower end of the outer case 110. The rotation part 150 is fixed to the lower fixing part 23 so that the rotation part 150 itself can be prevented from being idle on the fixing part 23. [

In another embodiment, the rotating portion may be disposed in the outer case inner space. Further, a plurality of rotating parts may be provided, and a plurality of rotating parts may be provided for each of a plurality of coils constituting the coil part 120. [ In this embodiment, the directions in which the plurality of coils constituting the coil part 120 are directed can be controlled to be different from each other.

The depth adjusting part 160 is connected to the coil part 120 and adjusts the depth of the coil part 120. By controlling the depth of the coil, one coil can be used to send or receive AC signals at different depths. Therefore, the depth adjusting unit 160 has an effect of sensing an AC signal at different depths even with a small number of coils.

In a preferred embodiment, the depth adjuster 160 may be installed at the top of the outer case 110, but is not limited thereto. The depth adjusting portion 160 may include a guide rail for guiding the movement of the coil portion 120 and a motor for controlling the depth for adjusting the depth of the coil portion 120.

4 is a diagram illustrating a configuration of a control unit of a subterranean environment change sensor according to an embodiment of the present invention.

4, the detection sensor 100 may include a coil part 120 and a control part 130. [ A multiplexer 140 may further be provided between the coil unit 120 and the control unit 130. [ The multiplexer 140 may connect the plurality of coils 120-1 to 120-n included in the coil part to one controller 130. [

The control unit 130 may include a communication unit 131, a central processing unit 132, a transmitting unit 133, a receiving unit 134, and a matching unit 135.

The communication unit 131 includes a wireless or wired communication module. The communication unit 131 may communicate with a plurality of detection sensors, communicate with a repeater, or communicate with a detection server. The communication unit 131 may transmit the AC signal size itself measured by the detection sensor or the detection result of the underground environment change of the control unit 130 and the like.

The central processing unit 132 is connected to the communication unit 131, the transmission unit 133, the reception unit 134, and the matching unit 135, and can execute the built-in firmware to organically operate the respective components.

The transmitting portion 133 transmits an AC signal. In a preferred embodiment, the transmitter 133 may include an oscillator for AC signal oscillation, and an amplifier for amplifying the oscillated signal. The AC signal oscillated in the transmitter 133 is transmitted to the other sensor in a magnetically induced manner through the coil part 120.

The receiving unit 134 senses the AC signal through the coil unit 120. In the preferred embodiment, the receiver 134 may include a rectifier for rectifying the sensed AC signal, and an analog-to-digital converter for converting the rectified analog signal to a digital signal. In another embodiment, the receiver 134 may include a down conversion mixer that outputs the frequency down.

In a preferred embodiment, one control section includes a transmitting section and a receiving section, and the transmitting section and the receiving section may be connected to one coil section. That is, the transmitter and receiver can transmit or sense signals through the same coil. In this embodiment, the control unit may block the operation of the receiving unit when the calling unit is operating, and may block the operation of the calling unit when the receiving unit is operating.

However, the present invention is not necessarily limited to these embodiments. The transmitter may be connected to the first coil group among the plurality of coils included in the coil section 120 and the receiving section may be connected to the second coil group among the plurality of coils included in the coil section 120. [ The first coil group is a coil different from the second coil group. For example, the transmitter may be connected to the odd-numbered coil, and the receiver may be connected to the even-numbered coil. In this embodiment, the controller can simultaneously transmit and sense an AC signal by simultaneously using the first coil group and the second coil group.

The operation of the transmitter and receiver will be described in more detail with reference to FIG. 5 and FIG. 6 as follows.

5 is a diagram showing signal processing of a transmitting unit and a receiving unit in an embodiment of the present invention. 5 (a) shows a signal transmitted from a transmitting unit during one period, and FIG. 5 (b) shows a process of processing a sensed signal.

As shown in Fig. 5 (a), the transmitter oscillates a specific AC signal for one period. There may be a pause at the beginning and end of one cycle.

As shown in FIG. 5 (b), the receiver resets the circuit for a predetermined time t1, and then rectifies the input signal (t2). Thereafter, the rectified analog signal is converted into a digital signal (t3). After the conversion, the circuit is reset again for a predetermined time t4.

FIG. 6 is a diagram illustrating a method of detecting an underground environment change event by analyzing a digital signal measured during a plurality of periods in an embodiment of the present invention. FIG. The subject detecting the underground environment change event may be the detection sensor or the detection server as described above.

In order to set a threshold as shown in FIG. 6, before starting the monitoring of the underground environment change, for example, immediately after the sensing sensor is embedded, an AC signal is exchanged between two different sensing sensors (In other embodiments, such reference data may not be generated).

Then, a predetermined threshold range is set above and below the reference data centering on the reference data.

Then, start S1 period and start full-scale underground environmental change monitoring. In the case where anomaly does not occur as in the periods S1 to S3, the measured digital signal does not deviate from the predetermined threshold range.

However, when anomaly occurs such as S4 period, the measured digital signal deviates from the critical range. If the digital signal is out of the critical range, it can be determined that a change in the underground environment has occurred.

7 is a diagram for explaining a matching unit of a control unit in an embodiment of the present invention.

The matching unit 135 matches the impedance to efficiently transmit and sense the AC signal. That is, the resonance frequency between the transmitting side and the receiving side is matched through impedance matching to increase the efficiency of signal sensing.

In a preferred embodiment, the matching unit 135 may include at least one or more variable capacitors. At least one or more variable capacitors may be connected to the coil in series, parallel, or series-parallel hybrid structures.

The matching unit 135 may adjust the capacitance of the variable capacitor included in the matching unit 135 to adjust the impedance ZIN of the coil unit 120 and the matching unit 135.

The control unit can control the matching unit for impedance matching. To explain this in more detail, referring to FIG. 8, it is as follows.

FIG. 8 is a flowchart showing impedance matching by the control unit according to an embodiment of the present invention. FIG.

As shown in FIG. 8, when it is determined that the resonance frequencies do not match, the controller first increases the capacitance of the matching unit for impedance matching (S1100).

Next, the AC signal is sensed again to determine whether the measured frequency and the resonance frequency coincide (S1200).

If the resonance frequencies do not match, it is checked whether the difference between the resonance frequency and the measured frequency is reduced (S1300).

If the frequency difference has decreased, go back to increasing the capacitance (S1100) and repeat the above steps.

If the difference in frequency is increased, it means that increasing the capacitance is a matching in the wrong direction, so the capacitance is decreased (S1400). After decreasing the capacitance, steps S1200 and S1300 are repeated to match the resonance frequencies.

In the above-described embodiment, the impedance matching is started in the direction of increasing the capacitance (S1100) at first. However, in another embodiment, the impedance matching may be started in the direction of decreasing the impedance.

By matching the resonance frequency of the receiving point with the receiving point through the impedance matching, the AC signal can be transmitted more efficiently.

9 is a diagram for explaining a queue factor in an embodiment according to the present invention.

The present invention further considers the Q factor in addition to the impedance matching around the resonance frequency f0.

In wireless communication, a coil having a low queue factor is used in consideration of data capacity. That is, the queue factor Q2 is lowered to secure the wide bandwidth BW2.

However, the present invention is not directed to wireless communication for transmitting and receiving data. SUMMARY OF THE INVENTION It is an object of the present invention to provide a sensor for detecting a change in the underground environment using a magnetic induction method. Therefore, in order to secure a longer sensing distance and a higher sensor sensitivity, a coil having a high queue factor Q1 is used at the expense of the bandwidth BW1.

f is the resonance frequency, L is the inductance of the coil, and r is the internal resistance of the coil, the queue factor (Q) can be defined by the following equation.

Q = wL / r, whrer w = 2? F

Therefore, when a material having a large value of L and a small value of r is used, the queue factor of the coil can be increased.

However, if the queue factor is large, the sensitivity of the sensor increases together, which may result in a decrease in stability. Therefore, an appropriate queue factor should be designed according to the installation purpose of the sensor, the installation location and spacing, and the characteristics of the ground medium.

10 is a diagram showing an enhancement of magnetic resonance using a second coil in an embodiment of the present invention.

The coil section (120 of FIG. 4) of the present invention may include a first coil section 121, 125 and a second coil section 123, 127.

The first originating coil 121 and the second originating coil 123 are the coils contained in the transmitting portion. The first reception coil 125 and the second reception coil 127 are coils included in the reception unit. The AC signals transmitted from the first and second transmitting coils 121 and 123 are transmitted to the first receiving coil 125 and the second receiving coil 127 through a strong magnetic field coupling.

In a preferred embodiment, the second coil portion 123, 127 has a higher inductance than the first coil portion 121, 125.

When the second coil sections 123 and 127 are used, there is an effect that the resonance characteristics can be enhanced by raising the queue factor of the transmitting section and the receiving section.

Figs. 11 and 12 are diagrams showing signals exchanged between a plurality of detection sensors according to an embodiment of the present invention. Fig.

FIG. 11 is a plan view showing a specific region in which a plurality of detection sensors S11 to S44 are buried, and FIG. 12 is a cross-sectional view illustrating reception of signals among a plurality of detection sensors.

The plurality of detection sensors shown in Fig. 11 form one sensor network. Sensors included in the sensor network exchange AC signals with each other. There may be various embodiments of the order in which the AC signals are exchanged between the detection sensors.

In one embodiment, when the detection sensors S11 to S14 sequentially transmit the AC signals, the remaining detection sensors can receive the signals. Thereafter, the detection sensors in the next column, S21 to S24, can proceed in a manner in which the AC signals are sequentially transmitted. For example, adjacent S12 and S21 detection sensors can receive a signal when the S11 detection sensor sends a signal. Next, the S11, S13, and S22 detection sensors can receive the signal when the S12 detection sensor sends a signal.

In another embodiment, one sensing sensor is capable of transmitting signals to adjacent sensing sensors while rotating. For example, the S33 detection sensor can rotate and emit a signal using the rotation unit (150 in Fig. 3). The S33 detection sensor can turn toward S34 after sending a signal with the S23 detection sensor oriented. Likewise, the S33 sensing sensor can turn toward the S43 sensing sensor after directing the signal towards S34. As described above, when the detection sensor is directed to the adjacent detection sensor and transmits a signal, the transmission / reception efficiency is increased.

As can be seen from FIG. 12, the plurality of coils included in one sensing sensor can transmit and receive signals with a time difference according to the depth.

In the embodiment as shown in FIG. 12 (a), the L1 coils can sequentially emit signals in the direction of the L5, L6, L7 and L8 coils. In the embodiment as shown in FIG. 12 (b), the L4 coil is directed to the L8 coil to generate a signal in such a manner that the L1 coil directs the signal to the L5 coil and then the L2 coil directs the signal to the L6 coil. It can send out.

By combining the embodiments of FIGS. 11 and 12, it is possible to collect three-dimensional path loss change data for an underground three-dimensional space embedded with a plurality of detection sensors. In addition, a three-dimensional space map indicating the path loss in the three-dimensional space can be created using this.

FIG. 13 is a flowchart illustrating a method of detecting a change in underground environment in an embodiment of the present invention. FIG.

As shown in FIG. 13, the sensing sensor matches the impedance with another sensing sensor (S2100) before or after the sensing of the underground environment change sensor is embedded in the ground. Matching the impedances can increase the magnetic resonance efficiency.

Next, the detection sensor transmits an AC signal in the underground (S2200).

Next, the sensing sensor senses the AC signal transmitted through the magnetic induction method using the first coil (S2300).

Specifically, the sensing sensor measures the magnitude of the sensed AC signal. Since the magnitude of the AC signal reflects the path loss according to the medium characteristics of the AC signal propagation path, the path loss can be measured by measuring the signal magnitude.

In a preferred embodiment, the sensing sensor may quantize the sensed signal by performing a step of rectifying the sensed AC signal to output an analog signal and outputting the analog signal as a digital signal. As described above, the use of the change in the size of the digital signal allows the path loss change due to the underground environment change in the signal transmission path to be known.

In another embodiment, the sensing sensor may sense the AC signal by simultaneously using a first coil and a second coil having an inductance greater than the first coil to enhance magnetic resonance.

Next, the detection sensor repeats the steps of transmitting and sensing the signal at predetermined intervals to measure the path loss variation according to the time transition (S2400).

Next, the detection sensor or the detection server determines that an underground environment change event has occurred (step S2500) when the path loss variation due to the time transition is out of the predetermined threshold range.

In another embodiment, a method for detecting a change in the underground environment includes a step of detecting a plurality of sensing sensors embedded in a three-dimensional space in the ground in a predetermined distance in X, Y, and Z directions, (magnetic induction) method.

Next, the underground environment change detection server analyzes signals transmitted and received between the plurality of detection sensors during one period, and extracts three-dimensional path loss data recording path loss between the respective sensors.

Next, the underground environment change detection server analyzes the three-dimensional path loss data extracted for each of a plurality of periods to generate a three-dimensional path loss change amount database according to the time transition.

Next, the underground environment change detection server analyzes the three-dimensional path loss change amount database and determines that an underground environment change event has occurred when a change of a predetermined threshold value or more is detected.

In another embodiment, the underground environment change detection server analyzes the three-dimensional path loss change amount database and can notify occurrence of an underground environment change event when path loss occurs continuously over a predetermined period. The change in the path loss may increase or decrease continuously for a predetermined period or more and predict a change of more than the threshold value may be predicted.

Next, the underground environment change detection server displays the position of at least two or more detection sensors where the underground environment change event occurs on the map on which the location where the detection sensors are buried, Displays the occurrence of a change event.

The underground environment change events may include at least one of sink hole occurrence, water and sewage leakage, underground structure deformation, and agricultural land moisture content reduction. That is, according to the present invention, when a sinkhole occurs and a pupil is generated, the water content of the soil is increased due to the leakage of water and sewerage, a deformation such as an underground structure is broken, or the moisture content of the agricultural land is reduced, And so on.

[Other Embodiments]

In another embodiment of the present invention, the receiver may be embedded in the ground and the transmitter may be located on the ground.

In another embodiment of the present invention, both the transmitting part and the receiving part may be buried on the ground. In this case, the signal transmitted from the calling section may be received by the receiving section through the ground. And may further include a reflection device for reflecting the outgoing signal to the reception part as the case may be.

In another embodiment of the present invention, the transmitting unit and the receiving unit may be included in one sensing sensor or may be included in different sensing sensors.

The scope of protection of the present invention is not limited to the description and the expression of the embodiments explicitly described in the foregoing. It is again to be understood that the present invention is not limited by the modifications or substitutions that are obvious to those skilled in the art.

Claims (19)

A subterranean environment change sensing sensor for sensing a change in an underground environment occurring in a medium on a propagation path between each of the plurality of sensing sensors by measuring a change in an alternating current signal propagated between a plurality of sensing sensors,
A coil part embedded in the ground and sensing an AC signal propagated through an underground in a magnetic induction manner; And
And a controller for repeatedly sensing the AC signal to measure a change amount of the AC signal. The method according to claim 1,
Wherein the coil unit senses the AC signal by a magnetic resonance method. 3. The method of claim 2,
Wherein the coil portion includes a first coil portion and a second coil portion having an inductance greater than that of the first coil portion. 3. The method of claim 2,
Wherein the coil portion includes a first coil portion and a second coil portion having a coil shape different from that of the first coil portion. The method according to claim 3 or 4,
Wherein the first coil unit is a spiral coil, and the second coil unit is a helical coil. The method according to claim 3 or 4,
Wherein the second coil part interlocks with at least two first coil parts to sense the AC signal. The method according to claim 1,
Further comprising a matching unit including at least one or more variable capacitors,
Wherein the control unit adjusts the capacitance of the variable capacitor to perform impedance matching with another underground environment change detection sensor. The method according to claim 1,
Further comprising a rotating portion for rotating the coil portion,
Wherein the control unit controls the rotation unit so that the coil unit directs the direction of the AC signal. The method according to claim 1,
Further comprising a depth adjusting section for adjusting a depth of buried portion of the coil section,
Wherein the control unit controls the depth adjusting unit so that the coil unit can receive an alternating current signal at a different embedment depth. The method according to claim 1,
Wherein the coil portion includes at least two coils spaced apart from each other in the depth direction of the ground. The method according to claim 1,
Further comprising a transmitter configured to generate an alternating current signal to be transmitted through the coil part to another underground environment change sensor. The method according to claim 1,
And a receiver for converting the AC signal sensed through the coil part into a digital signal. The method according to claim 1,
Wherein the controller determines that a change in the underground environment occurs when the AC signal is out of the critical range. delete At least one first sensing sensor embedded in the ground to transmit an AC signal in a magnetic induction manner;
At least one second sensing sensor embedded in the ground and sensing the AC signal transmitted from the first sensing sensor and propagating through the ground; And
And an underground environment change detection server for repeatedly measuring a change amount of the AC signal sensed by the second sensor and detecting a change in the underground environment,
The underground environment change detection server monitors a change in the underground environment occurring in the medium on the propagation path between the first sensor and the second sensor from the change of the AC signal due to the change in the medium property on the path on which the AC signal propagates Underground environmental change detection system. 16. The method of claim 15,
Wherein the underground environment change detection server determines that a change in the underground environment occurs when the AC signal is out of the critical range. 16. The method of claim 15,
Wherein the underground environment change detection server alerts the occurrence of a change in the underground environment when the AC signal continuously increases or decreases more than a threshold number of times. 16. The method of claim 15,
The underground environment change detection server analyzes a change in path loss due to a change in a medium property on a path through which the AC signal propagates from a change in the AC signal and detects a change in underground environment Wherein the underground environment change detection system comprises: 16. The method of claim 15,
The underground environment change detection server may detect at least one of a change in an underground structure including at least one of a change in a geological condition of an underground space, a change in groundwater distribution, a water supply and drainage pipe, a gas pipe, a pipeline, an electric line, Monitoring the underground environment change.

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