KR101570085B1 - Primary wave arrival time detecting apparatus and method - Google Patents

Abstract

In order to detect the position of a crack in a rock, the present invention detects a time point at which a P wave is reached from an elastic wave generated at the time of cracking of the rock. From the rock, a background noise and a P wave A variance value calculation unit for calculating a variance value from the amplitude values of the crack signal detected during a predetermined period of time; And a control unit for changing a variation value of the amplitude values sensed during the predetermined time from each of the changed reference points, wherein the control unit changes the predetermined time at least once And measures variations of the variance value for each changed time, A first time differ from each other more than the value from the first time the detection and detection is characterized in that for detecting the arrival time of the P wave.

Description

TECHNICAL FIELD [0001] The present invention relates to a P wave arrival time detecting apparatus and a P wave arrival time detecting apparatus,

The present invention relates to a detection device and a detection method for detecting a time at which a P wave arrives from an elastic wave generated when a rock is cracked, in order to detect a position of a crack in a rock.

The high - level waste core layer repository is a structure with a long - term life expectancy and has high stress from spent fuel, saturation due to ground water, and high ground stress due to deep conditions. The real - time monitoring of the long - term health of disposal rocks under these conditions and its structural damage assessment is a very important issue in terms of securing the reliability of the disposal system. In order to evaluate the degree of damage of the disposal rock, it is most important to locate the rock crack accurately.

Typically, radioactive waste repositories are formed by blasting and excavation. Therefore, there are myriad discontinuities in rock around the radioactive waste repository. This is a major cause of scattering and dispersion of seismic waves generated by cracks and interference of reflected waves, and forms background noise that is detected from the rock mass.

When cracks occur in the rock mass, P waves, which are seismic waves, are generated. Then, the generated P wave propagates in all directions around the crack position. Therefore, if the P wave is detected from the sensor attached to the rock, it is possible to detect whether or not the rock is cracked. If the first time the P wave arrives from each sensor is accurately detected, It is also possible to measure the position where it occurred. Therefore, it is very important to measure the presence or absence of the P wave and the first time point at which the P wave is reached.

However, the crack signal of the rock contains not only the P wave but also the background noise. Here, since the background noise and the P wave signal differ in their amplitudes, the presence or absence of the P wave can be easily distinguished. However, the point of time when the P wave starts is a problem that it can not be accurately measured by the background noise, that is, the ambient noise signal. Therefore, there is a need for a method that can accurately separate the background noise and the P wave.

It is an object of the present invention to provide a P wave detecting apparatus and a detecting method capable of accurately detecting the arrival time of a P wave from a crack signal detected in a rock.

A P wave arrival time detecting apparatus according to an embodiment of the present invention includes a sensing unit for sensing amplitude of a crack signal including a background noise and a P wave signal generated by cracking of the rock mass from a rock, And a variance value calculation unit for calculating a variance value from the amplitude values of the crack signal detected during the predetermined time period, And a controller for measuring a variation value of the amplitude values detected during the predetermined time, wherein the controller changes the predetermined time at least once, measures variations of the dispersion value for each changed time, The first time point at which the variation of the variance value by time differs from the predetermined threshold value is detected and the P wave It characterized by detecting a month's time.

In one embodiment, the preset time is a time within a time corresponding to the length of one wavelength of the P-wave signal, and the control unit sets the time within a time corresponding to the length of one wavelength of the P- The predetermined time is changed at least once.

In one embodiment, the controller changes the magnitude of the predetermined time based on a user's input within a time corresponding to the length of one wavelength of the P-wave signal.

A P wave arrival time detection method according to an embodiment of the present invention is a method for detecting a P wave arrival time from a rock mass and a crack signal including a P wave signal generated by a crack in the rock mass, Detecting a plurality of window regions having time regions of different sizes in the time domain according to a detection order of the detected crack signals in the time domain, Detecting a first arrival time of the P wave whose dispersion values calculated from the respective window regions differ from each other by a predetermined threshold value or more; And detecting the arrival time of the P wave.

In one embodiment, the calculating the variance values may include generating a window region having a time region of a predetermined size in the time domain, and generating the window region in a detection order of the detected crack signal Calculating the variance values for the amplitude variation values during the time included in the generated window region, changing the size of the time region of the window region, The window region generated according to the size of the changed time domain is moved in the time domain according to the detection order of the detected crack signal and the variance values of the amplitude change values during the time included in the generated window region And a step of calculating a difference value.

In one embodiment, the step of calculating the variance values may further include repeating the step of changing the size of the time domain and the step of calculating variance values corresponding to the changed time domain at least once. .

In one embodiment, the time domain of the different size is determined by a user's input within a size of a time domain corresponding to the length of one wavelength of the P wave signal in the time domain .

The apparatus and method for detecting a P wave arrival point according to an embodiment of the present invention measures variation of dispersion values according to a time when the crack signal is sensed from populations of different sizes set from a crack signal of a rock And detecting the arrival time of the P wave whose change in the measured variance values are different from each other, thereby detecting the arrival time of the P wave accurately.

1 is a block diagram of a P wave arrival time detecting apparatus according to an embodiment of the present invention.
2A is a diagram showing an example of a crack signal in which a background noise and a P-wave signal detected from a rock are mixed.
2B is a diagram showing an example of a P-wave signal and a background noise signal.
FIG. 3 shows an example of a variance value change of the background noise signal and the P-wave signal according to time.
4 is a diagram illustrating an example of detecting a time point at which a P wave signal arrives for the first time in the P wave arrival time detecting apparatus according to the embodiment of the present invention.
5 is a flowchart illustrating a method of detecting a P wave arrival time according to an embodiment of the present invention.
6 is a diagram illustrating an example of setting the size of a window region in the P wave arrival time detecting apparatus and method according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to the same or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. In addition, it should be noted that the attached drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical idea disclosed in the present specification by the attached drawings.

1 is a block diagram of a P wave arrival time detecting apparatus according to an embodiment of the present invention.

1, the P wave arrival time detecting apparatus according to the embodiment of the present invention includes a sensing unit 110, a dispersion value calculating unit 120, a memory unit 140, And a control unit (100) The P wave arrival time detecting apparatus according to an embodiment of the present invention may further include a display unit 150 and a user input unit 130.

The sensing unit 110 senses the amplitude of the crack signal including the background noise and the P wave signal generated by the crack of the rock when the detection of the crack position of the rock is started. Here, the sensing unit 110 may sense the crack signal as a change in amplitude with respect to time in the time domain.

2A shows an example of a crack signal in which a background noise and a P-wave signal sensed by the sensing unit 110 are mixed.

As shown in FIG. 2A, a background noise and a P-wave signal are mixed in the crack signal detected by the sensing unit 110. FIG. Since the amplitude of the P-wave signal is large as described above, the background noise and the P-wave signal can be distinguished from each other. However, as shown in FIG. 2A, at the time before the P-wave signal has a certain amplitude or more, it is difficult to distinguish between the P-wave and the background noise.

However, the background noise and the P-wave signal differ in their frequency characteristics and time domain characteristics. FIG. 2B is a graph showing the frequency characteristics and time-domain characteristics of the background noise and the P-wave signal.

FIG. 2B shows frequency analysis results of the P-wave signal and the noise signal generated in the rock bed. As shown in FIG. 2B, the background noise has a wide band frequency distribution, but the P wave has only a narrow frequency region, that is, a specific frequency generated by the crack (for example, a center frequency region of 10 kHz). That is, the background noise has a broad frequency distribution, but the P-wave has only a few specific frequencies.

Therefore, the characteristics of the noise signal and the P-wave signal are summarized in Table 1 below.

P wave signal Background noise Time domain Signal (amplitude) is large Signal (amplitude) is small in magnitude Frequency domain Frequency distribution in a narrow region Wide frequency band distribution

Therefore, when the amplitude of the P-wave signal in the time domain is larger than the amplitude of the background noise, the variance of the amplitude value of the P-wave signal and the background noise of the P- Will have a much larger value.

On the other hand, the variance value calculation unit 120 selects amplitude values corresponding to a predetermined time set from the control unit 100 as a population from the detection result of the crack signal, and calculates a variance value for the selected population. Here, the reference time point of the predetermined time may be changed by the controller 100. Then, the variance value calculation unit 120 selects the amplitude values corresponding to the preset reference time as the population based on the currently changed reference time. Therefore, if the reference time is changed, the size of the population to calculate the variance value is the same, but each amplitude value constituting the population can be changed.

The variance value calculation unit 120 may change the predetermined time under the control of the control unit 100. [ In this case, the variance value calculating unit 120 selects a population from the detection result of the crack signal according to the changed fixed time with reference to the reference time set by the controller 100, so that the size of the population, that is, The number of values can be changed.

Here, the controller 100 may set a predetermined time determined from the reference time point in the variance value calculator 120, but may set only the predetermined time and the changed reference point in the variance value calculator 120 Of course. In this case, the variance value calculation unit 120 selects the amplitude values corresponding to the predetermined time from the reference time set from the control unit 100 as a population, and calculates a variance value for the selected population.

A controller 180 controls the overall operation of each connected component. The control unit 100 sets the reference time point of the predetermined time and the predetermined time in the variance value calculation unit 120 when the detection unit 110 detects the cracking signal. When the variance value for the population corresponding to the predetermined time is calculated from the variance value calculation unit 120, the control unit 100 can change the reference time point as a reference of the predetermined time. Here, the control unit 100 may change the reference time according to the detected time order of the crack signal. The controller 100 may measure the change of the variance value according to the change of the position of the reference time point.

For example, if the predetermined period of time is 0.5 seconds and the preset reference time is 0 second, the variance value calculation unit 120 calculates the amplitude detected from 0 second (base time) to 0.5 second from the detection result of the crack signal You can select values as populations and calculate variance values. If the reference time is changed to 0.1 second by the control unit 100, the variance value calculation unit 120 selects the amplitude values detected within 0.1 seconds (changed reference time) from 0.6 seconds from the detection result of the crack signal as a population And the variance value can be calculated.

Then, the controller 100 calculates the variance value obtained by selecting the amplitude values detected between 0 and 0.5 seconds as the population and the variance value calculated by selecting the amplitude values detected between the 0.1 second and 0.6 second as the population Can be measured. Therefore, when the reference time point is continuously changed in accordance with the detected time order of the crack signal, the amplitude values are selected according to the time sequence in which the crack signal is detected at the population size corresponding to the currently set constant time, The variance values are measured.

This may be the same as when a fixed window area of a population size corresponding to the predetermined time is set and the window area is moved according to the time order in which the crack signal is detected. That is, the control unit 100 of the present invention sets a new window area by a window function that changes the start and end points of a predetermined time determined from the changed reference time point, The variance value can be calculated from the amplitude values of the crack signal included in the set window region.

Meanwhile, the predetermined time may be changed by the user or the control unit 100 at least once. If the predetermined time is changed, the window area corresponding to the predetermined time may be changed. In this case, the number of amplitude values of the crack signal that can be included in one window region is also changed according to the change of the window region, and the size of the population is changed accordingly. When the size of the population changes, the variance of that population also changes.

FIG. 3 shows examples of variance values calculated by a window region of a background noise signal and a P-wave signal, which are moved according to the time order of the detected crack signal.

3 (a) shows an example of variance values calculated from the background noise in graph form. As shown in Fig. 3 (a), the variance value calculated from the background noise is almost constant. This is because, as shown in FIG. 2B, the frequency of background noise is dispersed over a wide area. Accordingly, even if the size of the window area is changed, the variance does not change.

However, as shown in FIG. 3 (b), the variance value calculated from the P-wave signal can vary greatly. This is because the frequency of the P-wave signal is concentrated in a narrow region as shown in FIG. 2B. Also, according to the above reason, when a window area having a size different from the window area used in the case of FIG. 3B is used, variance values different from FIG. 3B can be calculated.

Therefore, if the size of the window region is changed to move the crack signal according to the detected time order, and the variance values for the amplitude values of the crack signal corresponding to the moved window region are calculated, Even if the size is changed, the dispersion values do not change. However, in the case of the P-wave signal, the dispersion values are different even if the size of the dough area is changed.

Therefore, even if the crack signal is a mixture of background noise and P-wave signal, it is possible to accurately detect the time when the P-wave is first detected by the sensing unit 110. [

FIG. 4 is a diagram illustrating an example of detecting a time point at which a P-wave signal arrives for the first time in the P-wave arrival time detecting apparatus according to the embodiment of the present invention.

4 (a), 4 (b), and 4 (c) illustrate a case where the window regions are different in size from each other, As shown in FIG. 4 (d) shows examples of variance values calculated from the respective window regions of (a), (b) and (c) of FIG.

Referring to FIG. 4 (d), it can be seen that the variance values calculated in FIGS. 4 (a), 4 (b) and 4 (c) are different from each other even after a certain point of time, even if they are the same crack signal. As shown in FIG. 4, even if the signals (a), (b), and (c) of FIG. 4 are the same crack signal, different window regions are used and the variance values .

Therefore, even if the size of the window region is different at the time when the P wave signal does not reach, since the variance value is obtained for the same background noise in all of FIGS. 4A, 4B, and 4C, That is, the same value (a state in which the value changes to a predetermined threshold value or less). However, at the time when the amplitude value of the P wave signal is included in the window region, the variance values calculated in FIGS. 4A, 4B, and 4C are increased due to the amplitude of the P wave signal which rapidly increases .

Here, the sizes of the variance values increased in FIGS. 4A, 4B, and 4C are different from each other. 4 (a), 4 (b), and 4 (c) show different sizes of populations for calculating variance values because the sizes of windows are different from each other. Therefore, as the size of the window region is larger, a larger number of crack signal amplitude values are set as the population, and thus the time point at which the amplitude value of the P wave signal is included in the window region may be slightly changed.

Further, as the size of the window region is larger, the amplitude values of the background noise signal are included more in the population. Therefore, at the time when the arrival time of the P wave signal is included in the window region, the increase amount of the dispersion value due to the amplitude of the P wave signal is small Can be.

For example, in Fig. 4A where the window area is the smallest, the magnitude of the amplitude suddenly increases within the narrowest window area, and thus the increase amount of the variance among the set values is greatest. On the contrary, in FIG. 4 (c) having the widest window area, the magnitude of amplitude in the widest window area becomes larger, so that the increase amount of the dispersion value among the set is the smallest.

Therefore, at the time when the amplitude of the P wave signal is included in the window region, the variance values calculated in (a), (b), and (c) of FIG. Therefore, the controller 100 uses the characteristic that the variance values are different at the time when the P wave signal arrives when the window regions are different from each other, so that the control unit 100 detects the arrival point of the P wave signal from the crack signal mixed with the background noise and the P wave signal Can be accurately detected.

In order to change the size of the window area, the control unit 100 may include the window area setting unit 102. FIG. The window region setting unit 102 may be implemented within the control unit 100 or may be implemented separately from the control unit 100 outside the control unit 100. [ The controller 100 may determine the size of the window area through the window area setting unit 102 and may set the window area in the variance value calculator 120 according to the determined size.

The window region setting unit 102 may change the size of the window region. As described above, the window region setting unit 102 can change the size of the window region according to the size of the time input from any one of the preset predetermined time periods or from the user. The control unit 100 may set a window region determined according to the changed size in the variance value calculation unit 120. [ The variance value calculation unit 120 calculates a variance value corresponding to the window area set to a different size.

In addition, the controller 100 moves the currently set window area in the time domain, i.e., in the time order in which the crack signal is detected along the time axis. That is, as shown in FIGS. 4A, 4B, and 4C, the controller 100 moves the currently set window area along the time axis and moves the population included in the moved window area The amplitude value of the crack signal included in the crack signal).

If the size of the window area is changed, the controller 100 moves the window area of the changed size along the time axis in the order in which the amplitude value of the crack signal is sensed. If the magnitude of the P wave signal is included in the window region, the amplitude of the crack signal is calculated in the window region of different magnitudes The dispersion values are also different from each other.

The control unit 100 can measure the variation of the variance value calculated according to the movement of the time axis of each window region. If the size of the window area is changed, the controller 100 may separately measure the variation of the variance value corresponding to the size of the changed window area. For example, as shown in (c) of FIG. 4, the controller 100 may measure the variance of the variance corresponding to the size of the different window region and display the variance in a graph form.

For this, the control unit 100 may include a variance value variation measurement unit 104. The variance value variation measurement unit 104 may be implemented within the control unit 100 or may be separately provided outside the control unit 100 .

Meanwhile, the control unit 100 sets window regions of different sizes, and moves the window regions along the time axis in the order in which the amplitudes of the crack signals are sensed, and moves the population regions included in the moved window regions 4) that the first point of arrival of the P-wave signal can be detected by calculating the variance value from the amplitude values of the included crack signals and comparing them. However, it goes without saying that the control unit 100 may detect the time at which the P-wave signal is detected by the sensing unit 110 using the initial point of arrival of the P-wave signal.

For example, the user of the P wave arrival time detecting apparatus according to the embodiment of the present invention can detect the arrival time of the P wave arrival time detecting apparatus of the P wave arrival time detecting apparatus according to the embodiment of the present invention, The detection of the crack signal can be started. In this case, the user can input into the controller 100 a point of time when the rock is generated by the user, such as blasting, excavation, or an artificial micro-failure sound for searching for cracks or cracks in the rock. The control unit 100 may control the sensing unit 110 so that the sensing unit 110 senses a crack signal sensed from the rocking point after the input point.

In this case, when the detection of the cracking signal is started, the control unit 100 can detect the first arrival time of the P wave from the crack signal in which the P wave signal and the background noise are mixed, as described with reference to FIG. When the P wave signal is detected for the first time, the time from the time point to the start of the first detection can be detected as the arrival time of the P wave reaching the sensing unit 110. The controller 100 may include a P wave arrival time detector 106. The P wave arrival time detector 106 may be implemented within the controller 100 or separately from the controller 100, (Not shown).

It goes without saying that the P wave arrival time detecting unit 106 may detect the crack position of the rock directly from the rock as the case may be. For example, if there are a plurality of sensing units 110, and if the sensing unit 110 is located at a different arbitrary position of the rock, the P wave arrival time detection unit 106 detects It is also possible to directly detect the crack position of the rock by using the P wave arrival times.

Meanwhile, the memory unit 140 may store a program for the operation of the controller 100, and the memory unit 140 may store input / output data (for example, A measured value obtained by measuring a change in the variance value, or the arrival time of the P wave or the arrival time of the P wave) may be temporarily stored.

The user input unit 130 may be configured to allow the user to input data for controlling the P wave arrival time detecting apparatus according to the embodiment of the present invention (for example, starting time of detecting the crack position of the rock mass, ). The user input unit 130 may include a key pad, a dome switch, a touch pad (static / static), a jog wheel, a jog switch, and the like.

The display unit 150 displays (outputs) the information processed by the P wave arrival time detecting apparatus according to the embodiment of the present invention. For example, as shown in FIGS. 4A, 4B, and 4C, a change in dispersion value calculated while moving window regions of different sizes along the time axis is displayed (for example, (d)).

Or a UI (User Interface) or a GUI (Graphic User Interface) for receiving an input for setting the sizes of the different window areas from the user. In this case, the controller 100 may determine the size of the window area corresponding to a plurality of times input from the user, and display the generated window area on the display unit 150.

The display unit 150 may be a liquid crystal display (LCD), a thin film transistor-liquid crystal display (TFT) liquid crystal display (LCD), an organic light-emitting diode (OLEd), a flexible display a flexible display, a three-dimensional display, and an e-ink display.

Also, the display unit 150 may have a mutual layer structure (hereinafter referred to as 'touch screen') for sensing a touch operation (hereinafter, referred to as 'touch sensor'). In this case, the display unit 150 may be used as the user input unit 130 in addition to the output device. The touch sensor may have the form of, for example, a touch film, a touch sheet, a touch pad, or the like.

The touch sensor may be configured to convert a change in a pressure applied to a specific portion of the display unit 150 or a capacitance generated in a specific portion of the display unit 150 into an electrical input signal. The touch sensor can be configured to detect not only the position and area to be touched but also the pressure at the time of touch.

If there is a touch input to the touch sensor, the corresponding signal (s) is sent to the touch controller. The touch controller processes the signal (s) and then transmits the corresponding data to the control unit 100. Thus, the control unit 100 can know which area of the display unit 151 is touched or the like. In addition, the controller 100 may determine the size of the window area according to the size of the region that is touched by the user.

In accordance with a hardware implementation, the embodiments described herein may be implemented as application specific integrated circuits (ASICs), digital signal processors (dSPs), digital signal processing devices (dSPds), programmable logic devices (PLds), field programmable gate arrays (FPGas) , Microprocessors, microprocessors, microprocessors, and other electronic units for carrying out other functions. In some cases, the embodiments described herein may be implemented by the control unit 100 itself.

According to a software implementation, embodiments such as the procedures and functions described herein may be implemented with separate software modules. Each of the software modules may perform one or more of the functions and operations described herein.

The software code may be implemented in a software application written in a suitable programming language. The software code is stored in the memory unit 140 and can be executed by the control unit 100. [

5 is a flowchart illustrating a method of detecting a P wave arrival time in the P wave arrival time detecting apparatus according to the embodiment of the present invention.

The control unit 100 detects a crack signal from the rock (S500). Here, the control unit 100 controls the rocking of the rock mass after the specific point of time selected from the user, that is, when the rocking of the rock is started, or when the rocking sound is generated to detect the presence / It is possible to detect a cracking signal. The crack signal is a mixed signal of P wave signal and background noise generated in the crack of the rock.

When a crack signal is detected, the controller 100 generates a window area having a size of a time domain corresponding to a currently set time (S502). Then, the control unit 100 sets the generated window region in the variance value calculation unit 120 and moves the crack signal along the time axis in a time sequence in which the crack signal is sensed (S504).

The controller 100 controls the variance value calculator 120 to select amplitude values of the crack signal included in the window region moving along the time axis as a population and to calculate a variance value from the selected population (S506 ). Therefore, the controller 100 calculates the variance value of the amplitude values of the crack signal in the order of the detected time of the amplitude value of the crack signal, The change of the dispersion value can be measured.

Here, the controller 100 may determine whether a change in the variance value according to the size of the currently set window area is sufficiently measured. For example, the control unit 100 may determine that a change in the dispersion value is sufficiently measured when a point of time at which the P wave first arrives is detected. Or it may be determined that a change in the variance value has been sufficiently measured according to a predetermined time or the like from the user.

Meanwhile, the controller 100 can change the size of the currently set window area. If the variance value according to the size of the currently set window area is set, the controller 100 may determine whether the size of the window area has changed by a predetermined number of times or more (S508). The predetermined number of times may be arbitrarily determined by the user, or may be determined by selecting the appropriate number of times that the controller 100 determines to be the most preferable. For example, the controller 100 may determine an appropriate number of times, which is determined to be the most preferable, according to whether or not the time when the P-wave signal first arrives is detected.

If it is determined in step S508 that the size of the window area is not changed by a predetermined number of times, the controller 100 may change the size of the window area in step S510. Here, when the size of the window region is changed, the size of the corresponding time region is also changed, thereby changing the number of amplitude values of the crack signal included in the window region. That is, the size of the population for calculating the variance value is changed. When the size of the population is changed, the variance value when the amplitude of the P wave signal is included in the population can also be changed.

)은 하기 수학식 1로 표현할 수 있다.E.g. The amplitude values of the crack signal included in the window region (

) Can be expressed by the following equation (1).

는 윈도우 함수,

는 무빙 윈도우의 크기, N은 윈도우 데이터 개수,

는 샘플링 주기를 의미한다. here,

Is a window function,

Is the size of the moving window, N is the number of window data,

Means a sampling period.

However, since the dispersion is expressed by the following equation (2)

The dispersion equation for obtaining the variance value from the crack signal corresponding to the window region can be expressed by Equation (3).

)를 분산식에 대입하여 정리하면, 하기 수학식 4와 같이 유도되어 질 수 있다. Here, the amplitude values of the crack signal (

Can be derived as shown in the following equation (4). &Quot; (4) "

Also, for example, as shown in FIG. 2A, in the case of a crack signal in which background noise and a P-wave signal are mixed, the crack signal can be expressed by a sum of a background noise and a P-wave signal. In this case, if the background noise is 0 and the white noise is assumed, the background noise can be derived as shown in Equation (5) by substituting the background noise into the equation (4).

와 관계없이 항상 일정한 값을 가짐을 확인할 수 있다. As shown in Equation (5), the background noise is the size of the window area

It can be confirmed that it always has a constant value.

를 가지는 사인파(sine wave)로 가정하면 하기 수학식 6과 같이 표현할 수 있고,On the other hand, when the P wave signal is included,

, It can be expressed as the following Equation (6). &Quot; (6) "

The above Equation (6) can be derived by substituting the Equation (4) into Equation (7).

As shown in Equation (7), since the P wave is a function of the window size T, the dispersion can be changed according to the size of the window. Therefore, as shown in Equations (5) and (7), when a P-wave signal exists in the background noise, the variance value of the P-wave signal varies, and the degree of variation of the variance value can be determined according to the size of the window region.

If the window size is changed in step S508, the control unit 100 moves the changed window area along the time axis in a time sequence in which the crack signal is detected in step S504. (S506) of calculating the variance value from the amplitude values of the crack signal. If the size of the window area is changed more than the predetermined number of times in step S508, the variation of the variance values calculated from the window areas having different sizes is measured, and the first arrival time of the P wave is detected from the measured changes (S512). In step S512, the controller 100 compares the variance values calculated from the window areas having different sizes, and detects the first time point at which the calculated variance values are different from each other, to the point when the P wave signal first arrives can do.

The step S512 may further include a step of measuring the arrival time of the P wave from the point of arrival of the detected P wave. For example, when the first arrival time of the P wave signal is detected in step S512, the control unit 100 determines the time from when the detection of the crack signal starts to when the P wave signal reaches the first time, It can be determined that the time has reached the portion 110. [

On the other hand, the controller 100 may set the size of the window area and use the predetermined time or predetermined predetermined time as a reference to change the size of the set window area at least once.

As described above, the present invention calculates the variance while changing the size of the window, so that the size determination of the window can be the most important factor in detecting the arrival point of the P wave at the first time.

FIG. 6 is a diagram illustrating an example of setting the size of a window region in the P wave arrival time detecting apparatus and method according to the embodiment of the present invention.

FIG. 6A is a graph showing the relationship between the P-wave signal and the P-wave signal shown in FIG. 6A, assuming that the P-wave is a sinusoidal wave as assumed in Equation 6. FIG. And variance values that can be calculated by the variance value calculator 120 in graph form.

Referring to FIG. 6 (b), it can be seen that the variation amount of the variance value within the time corresponding to the point b is the largest from the start of the P wave signal. The time corresponding to the time point b from the start of the P-wave signal is within a time corresponding to the length of one wavelength of the P-wave signal in FIG. 6 (a) . Therefore, when the size of the window region is set to a time within a time corresponding to the length of one wavelength of the signal assuming the P-wave to be a sinusoidal wave, the variation amount of the dispersion value can be maximized. Accordingly, the difference in the dispersion value determined according to the window size can be maximized.

Accordingly, the controller 100 sets the size of the window area to a time within a time corresponding to the length of one wavelength of the P wave in setting the size of the window area and changing the size of the set window area at least once. And it may be most desirable to change.

Further, according to the embodiment disclosed herein, the above-described method can be implemented as a code that can be read by a processor on a medium on which the program is recorded. Examples of the medium that can be read by the processor include ROM, RaM, cd-ROM, magnetic tape, floppy disk, optical data storage, etc., and may be implemented in the form of a carrier wave (e.g., transmission over the Internet) .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (7)

A sensing unit for sensing an amplitude of a crack signal including a background noise and a P wave signal generated by cracking of the rock mass from a rock;
A variance value calculation unit for calculating a variance value from the amplitude values of the crack signal detected during a predetermined time; And
And a controller for changing the reference time of the preset time in accordance with the time order of the sensed crack signals and measuring the variation of the variance value of the amplitude values sensed during the predetermined time from each of the changed reference times,
Wherein,
Wherein the first time point at which the variation of the variance value for each time is different from the predetermined threshold value is detected and the P The arrival time of the wave is detected,
The predetermined time may be,
A time within a time corresponding to the length of one wavelength of the P wave signal,
Wherein,
Wherein the predetermined time is changed at least once within a time corresponding to the length of one wavelength of the P wave signal.
delete The apparatus of claim 1,
And changes the size of the predetermined time based on a user's input within a time corresponding to the length of one wavelength of the P-wave signal.
Detecting a crack signal including a background noise from a rock and a P wave signal generated by a crack of the rock mass as an amplitude change with time in a time domain;
A plurality of window regions having time regions of different sizes in the time domain are changed in accordance with the order of detection of the crack signals detected in the time domain, Calculating variance values for amplitude variation values during time included in each window region;
Detecting a first arrival time of the P wave whose variance values calculated from the respective window regions differ from each other by a predetermined threshold value or more; And
And detecting the arrival time of the detected P wave.
5. The method of claim 4, wherein the calculating the variance values comprises:
Generating a window region having a time domain of a predetermined size in the time domain;
Moving the generated window region in the time domain according to a detection order of the sensed crack signal and calculating variance values for amplitude change values during a time included in the generated window region;
Changing a size of a time domain of the window region; And
A window region generated according to the size of the changed time domain is moved in the time domain according to a detection order of the detected crack signal and a dispersion value of amplitude change values during a time included in the generated window region And calculating the P wave arrival time.
6. The method of claim 5, wherein the calculating the variance values comprises:
Further comprising repeating at least one time of changing the size of the time domain and calculating variance values corresponding to the changed time domain.
5. The method of claim 4,
Wherein the P-wave arrival time is determined by a user's input within a size of a time domain corresponding to a length of one wavelength of the P-wave signal in the time domain.

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