KR20170027171A

KR20170027171A - Coastal Control point for Photogrammetry

Info

Publication number: KR20170027171A
Application number: KR1020150123771A
Authority: KR
Inventors: 정의영; 노경찬; 박준용
Original assignee: 한국해양과학기술원
Priority date: 2015-09-01
Filing date: 2015-09-01
Publication date: 2017-03-09
Also published as: KR101804181B1

Abstract

Disclosed is a coastal control point sign for photogrammetry. According to the present invention, the coastal control point sign for photogrammetry comprises: an identification sign part including a sign formed on an upper surface or surface to be identified from the sky for photogrammetry; a GPS receiver installed in a side of the identification sign part to receive position information from a satellite; a body combined with a lower part of the identification sign part, including an information processing device installed inside to store and process the position information received by the GPS receiver, including a float formed on a lower part to float on the water surface; a fixing unit fixated to the floor surface of an installation position; and a length control unit connecting the body with the fixing unit, but changing its length depending on a change of water level to make the body always float without leaving from the installation position. According to the present invention, the coastal control point sign for photogrammetry is capable of securing a more precise photogrammetry, and reducing a measurement error in a coastal area or riverine area by adding and supplementing marine or riverine GCP data through the identification sign part, the GPS receiver, and the information processing device.

Description

{Coastal Control point for Photogrammetry}

The present invention relates to a coastal reference point sign for photogrammetry, and more particularly, to provide a GCP data on the sea or a stream to be supplemented or supplemented, thereby reducing a surveying error in a coastal area or a river area, The present invention relates to a coastal reference point sign for photogrammetry which can provide accurate GCP data by maintaining a stable position without detaching from an installation position even in a tidal zone where the tidal difference is large.

Mapping and surveying through aerial photographing is done by photographing aerial photographs for the target area, then painting and positioning. Since aerial photographs contain geometric distortions due to various factors, it is necessary to correct the distortion of the photographs by using the correction formula that can link the actual coordinates with the data collected through the ground reference point (GCP) And at the same time converting the spatial coordinate system of the photograph into the coordinate system of the actual object area.

In addition, facial expressions are performed to give accurate coordinates to aerial photographs, which are divided into an inner facial expression phase and an outer facial expression phase. The inner facial expression step is a step of matching the photographs, performing focal length correction, elasticity correction, etc. to reflect the optical environment at the time of photographing, and the outer facial expression step is for identifying the positional relationship between the camera and the object. This is the step of transforming the geometric relationships between several photographs into actual three-dimensional coordinates using at least 6 ground reference points (GCP) data.

In conventional photogrammetry, to obtain such GCP data, a reference point is selected for the actual feature of the airline truth, and the actual coordinates of the ground reference point must be acquired through the precision measurement method such as total station or GPS survey Time and cost.

In addition, GCP data for land areas can be acquired easily by GPS survey as described above. However, when it is difficult to install GCP in coastal areas or river areas, (GCP) data is difficult to obtain, the accuracy of surveying becomes poor and the surveying error increases.

As a prior art for improving these problems, Korean Patent Registration No. 10-0915600 discloses a technique in which a mark that can be distinguished from an aerial image is installed at a reference point that knows three-dimensional coordinates and is used as a ground reference point, Dimensional coordinates of the three-dimensional coordinate system of the three-dimensional coordinate system.

However, this technology also has the problem that it is difficult to install an identifiable sign on the surface of the sea and rivers, and in the case of a tidal zone where there is a large difference between tides, there is a problem that the identification mark is locked in the water. There is a problem that the accuracy of the survey can not be secured.

Korean Registered Patent No. 10-0915600 (Publication Date 2009.09.07)

It is an object of the present invention to provide a method and apparatus capable of reducing the measurement error in the coastal area and the river area by ensuring that the GCP data on the sea or on the river can be added and supplemented to secure the precision of the photogrammetry, And to provide a coastal reference point sign for photogrammetry that can provide accurate GCP data by firmly maintaining its position without departing from the installation location.

The above object is achieved by an image processing apparatus comprising: an identification sheet portion on an upper surface or a surface thereof, A GPS receiver installed at one side of the identification sheet and receiving position information from a satellite; An information processing device coupled to a lower end of the identification sheet portion and storing and processing positional information received by the GPS receiver and having a buoyant body formed at a lower end thereof so as to float on a surface of the body; Fixing means fixed to the bottom surface of the surface mounting position; And a length adjusting means for connecting the body and the fixing means so that the length of the body varies with the variation of the depth of the water to allow the body to always float without deviating from the installation position. Lt; / RTI >

Wherein the length adjusting means comprises: a wire having one end connected to the fixing means; A tension measuring sensor installed at one side of the wire to measure a tension applied to the wire according to a variation in depth of water; And a winding means installed inside the body and connected to the other end of the wire, and winding means for winding or unwinding the wire according to the tension measured through the tension measurement sensor.

At least two length adjusting means may be provided at positions symmetrical to each other with respect to the body.

Wherein the length adjusting means comprises: a helical spring; A shaft engaged with one side of the helical spring to receive an elastic force by the helical spring; A wire having one end engaged with one side of the shaft and wound or unwound on the shaft, and the other end coupled with the fixing means; And a bracket installed at one side of the body to fix the shaft rotatably.

And a mounting means formed at the lower end of the body so as to maintain the state of being separated from the bottom surface when the body is close to the bottom surface.

The identification sheet portion may be formed in the form of a flat plate having a predetermined width.

The GPS receiver may be installed at the center of the identification sheet portion.

The GPS receiver may be installed symmetrically at the same distance with respect to the center of the identification sheet portion.

According to the present invention, as the GCP data on the sea or river are added or supplemented through the identification sheet section, the GPS receiver, and the information processing apparatus, it is possible to reduce the surveying error in the coastal area or the river area, It is possible to provide a coastal reference point sign for photogrammetry.

Further, by providing the length adjusting means, it is possible to provide a coastal reference point sign for photogrammetry which can provide accurate GCP data by maintaining a stable position without leaving the installation position even at a tidal zone where the difference between the tide gaps is severe.

Further, by providing the mounting means, it becomes possible to prevent the body from being inverted by the protruding terrain of the sea floor, so that it becomes possible to provide a coastal reference point sign for photogrammetry which can always make the identification mark portion face upward.

1 is a perspective view of a coastal reference point sign for photogrammetric survey according to an embodiment of the present invention.
2 is an exploded perspective view of FIG.
FIG. 3 is a view showing an operation state according to the variation of water depth of the coastal reference point sign of FIG. 1;
4 is a perspective view showing a length adjusting means according to a modification of the present invention.
5 is a diagram illustrating a GPS receiver installed according to a modification of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the well-known functions or constructions are not described in order to simplify the gist of the present invention.

1 is a perspective view of a coastal reference point sign for photogrammetric survey according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of FIG. 1, and FIG. 3 is an explanatory view to be. FIG. 4 is a perspective view illustrating a length adjusting unit according to a modification of the present invention, and FIG. 5 is a view illustrating a GPS receiver installed according to a modification of the present invention.

As shown in FIGS. 1 to 3, the coastal reference point sign 100 for photogrammetry according to the present invention floats at a specific location on the water surface, and becomes a basic data of photogrammetry, (Ground Control Point) data, which is a reference point used to obtain the GCP (Ground Control Point) data.

This is an improvement of the difficulty in obtaining the data of the GCP because it is difficult to install the GCP on the sea or the river. It is necessary to add GCP data on the GCP data of the land area or the GCP data on the river area, This is to reduce the error and ensure the precision of photogrammetry.

The coast reference point sign 100 for photogrammetry according to the present invention includes an identification sheet 110, a GPS receiver 120, a body 130, A fixing means 140, a length adjusting means 150, and the like.

A detailed description of each of the above-described configurations is as follows.

The identification sheet 110 refers to a mark formed on the upper surface or the surface of a sign (color or color) that can be identified even in the sky when photographing is performed using a flight device such as an aircraft or a flight device such as a drone. The identification sheet 110 can be easily identified on photographed measurement photographs to help determine whether or not the consecutive photographs are matched.

The mark formed on the identification sheet 110 may be any shape, shape, or color that can be ascertained from above.

However, the identification sheet 110 according to the embodiment of the present invention is formed in a square shape as a whole, and each divided space divided into four in a cross shape is colored in white and black without neighboring each other. Because of the combination and arrangement of these colors, they can be easily identified in the sky and can be easily recognized on photographed photographs.

At this time, the identification sheet 110 is formed in the form of a flat plate having a predetermined width, and the width thereof is determined according to the width of the measurement range. That is, when the measurement range is wide, the area of the identification sheet 110 may be enlarged, and when narrow areas are measured using a flying object such as a drone, the square may be formed with a width of 30 cm to 50 cm.

The GPS receiver 120 is a component that calculates and calculates position coordinates (X, Y, Z coordinate values) and observation times (hereinafter referred to as 'position information') based on satellite signals received from four or more satellites . A plurality of products having various functions and specifications are currently available on the market, and a detailed description thereof will be omitted, and only the characteristic parts will be described.

The GPS receiver 120 according to the embodiment of the present invention uses Real Time Kinematic (RTK) GPS to enhance the real-time measurement and accuracy of the position information, and is installed at one side of the identification sheet 110.

Here, the term " one side " means that the satellite signal can be completely received without external interference, and the location where the reference point of the position information calculation of the corresponding GPS receiver 120 is placed on the same plane as the identification sheet 110 is sufficient.

However, if the position information is obtained by using one GPS receiver 120, it is preferable to install it in the center of the identification sheet 110. This is to ensure the accuracy of the position information and the simplicity of post-processing of the position information.

The body 130 accommodates various kinds of equipment and the like and is capable of floating on the water surface of the coast reference point signboard 100 according to the present invention and is connected to the lower end portion of the identification sign portion 110 do. In this case, the water-tight coupling does not allow the outside water to flow into the body 130.

The shape of the body 130 can be changed into various shapes such as a disc shape as required, as well as an overall square shape like the identification sheet 110.

The body 130 according to the embodiment of the present invention may include the information processing device 132 and the buoyant body 134 and the like.

The information processing device 132 is installed in a receiving space 131 provided inside the body 130 and stores and processes the positional information received by the GPS receiver 120 in electrical communication with the GPS receiver 120, And can control the length adjusting means 150 to be described later.

Specifically, the information processing apparatus 132 includes a central processing unit (CPU, not shown) for processing position information and controlling the apparatus, a flash memory (not shown) for storing the processed information, A circuit board (not shown) and a power supply device (not shown) for electrically connecting the devices. With this configuration, the position information received by the GPS receiver 120, that is, the X, Y, Z coordinate values and observation time can be stored in the flash memory as a storage device for each measurement time.

The detailed description of the hardware constituting the information processing device 132 other than the above-described contents and the method for controlling the hardware according to the necessity thereof can be easily understood and implemented by those skilled in the art, so a detailed and general description thereof is omitted do.

The buoyant body 134 supports the identification sheet 110 and the body 130 and is provided with a component 130 provided at the lower end of the body 130 so that they can drift without sinking below the water surface in a river, to be. Since the buoyant body 134 may be of any shape or material conventionally used, it may be formed into a tube shape into which air is introduced, or it may be made of a foamed synthetic resin or the like coated with an external coating.

However, the buoyant body 134 according to the embodiment of the present invention is formed of a foamed synthetic resin having a square shape corresponding to the outer shape of the identification sheet 110 and the body 130, and having a predetermined thickness but extended outwardly. Thus, stable floating of the coastal reference point sign 100 and stable support of the body 130 can be achieved, and the overall appearance of the overall appearance can be achieved.

Further, since the shape of the buoyant body 134 having elasticity in a predetermined range due to the nature of the foamed synthetic resin and the shape of the buoyant body 134 formed outwardly expanding can effectively disperse the impact applied from the outside, the information processing apparatus mounted on the inner body 130 It is possible to perform stable operation such as the operation unit 132 and the like.

A seating space 134A is formed at the center of the buoyant body 134 so that the lower portion of the body 130 forming the accommodation space 131 can be fitted tightly, thereby preventing the body 130 from being separated from the buoyant body 134 And the supporting force against the body 130 can be further strengthened.

Meanwhile, the buoyant body 134 can selectively change the thickness of the buoyant body 134 and the degree of expansion of the buoyant body 134 to such an extent that buoyancy is generated such that the body 130 is not immersed below the water surface.

The fixing means 140 is a component provided to prevent the coastal reference point signboard 100 according to the present invention installed in a river, a lake, and the ocean from being deviated from the installation position by currents, rivers, winds,

That is, the fixing means 140 can be realized by constructing a fixed fixture (not shown) by a concrete pouring method, as a fixture fixed to the bottom surface (river bottom, lake bottom, But may be implemented in the form of an anchor of a ship, such as the securing means 140 according to an embodiment of the present invention. In this case, the weight of the anchor should be sufficient to prevent dragging by currents, currents, rivers and winds in the installation area, and it can be appropriately increased or decreased according to the characteristics of the installation area.

The length adjusting means 150 is provided to connect the body 130 and the fixing means 140 so that the length of the body 130 is variable according to the variation of the depth of the water, Element.

That is, as shown in FIG. 3, the length adjusting means 150 may extend the length of the body 130 in order to prevent the body 130 from being immersed in water during a high tide in a region where the difference between the tides is large, The length is reduced to prevent dragging along the currents of the algae.

The length adjusting means 150 according to the embodiment of the present invention may include the wire 152, the tension measuring sensor 154, the winding means 156, and the like.

The wire 152 is a constituent element having one end connected to the fixing means 140 and the other end connected to the winding means 156. The wire 152 can be wound or unwound by the winding means 156, Anything that satisfies these qualities is acceptable. However, since the wire 152 must be firmly connected to the fixing means 140 and the winding means 156, it is preferable to use a wire or nylon yarn having a small elongation and a large tensile strength.

The tension measuring sensor 154 is a component installed at one side of the wire 152 to measure the tension applied to the wire 152 in accordance with the variation of the water depth. The tension measuring sensor 154 is implemented as a tension load cell or piezo, And generates an electrical signal in accordance with the tension applied to the wire 152.

At this time, the tension measuring sensor 154 may be installed on the wire 152 adjacent to the anchor, which is the fixing means 140, or may be provided on one side of the body 130 so as to measure the tension applied to the winding means 156 itself As shown in FIG.

When the tension measured on the wire 152 is measured by the tension measuring sensor 154, the measured value is transmitted to the information processing apparatus 132 described above. Thereafter, the information processing apparatus 132 applies the winding means 156 It is controlled according to the situation.

The winding means 156 is provided inside the body 130 and connected to the other end of the wire 152 and is a component that winds or unwraps the wire 152 according to the tension measured by the tension measuring sensor 154.

Such a winding means 156 is driven by a power device such as a motor and can be easily implemented through appropriate modification of the general winding device and can be used to unwind or wind the wire 152 through the control of the above- do.

The above-described length adjusting means 150 may include one wire 152, one tension measuring sensor 154, and one winding means 156 to implement the above-described functions.

A winding means 156 connected to the other end of the wire 152 is installed inside the body 130 and one end of the wire 152 passes downward from the center of the inside of the body 130 and is connected to the fixing means 140 . At this time, the tension measuring sensor 154 is installed on the wire 152 adjacent to the anchor, which is the fixing means 140, to measure the tensile force on the wire 152, and the electrical signal generated according to the strength of the tension (Not shown) of the body 130 to the information processing device 132 inside the body 130. Here, a separate wire can be integrally formed with the wire 152 for simplification of the apparatus.

At least two length adjusting means 150 including the wire 152, the tension measuring sensor 154 and the winding means 156 may be provided at positions symmetrical to each other with respect to the body 130. In this case, the symmetrical structure is to maintain the balance of the body 130.

That is, if there are two length adjusting means 150, the winding means 156 are formed to be 180 degrees and symmetrically arranged inside the body 130, and then each wire 152 passes through the body 130 If there are three anchors which are the fixing means 140, the winding means 156 are respectively installed at an inner angle of 120 °.

As shown in FIGS. 1 and 2, when four length adjusting means 150 are provided, the winding means 156 is installed at each corner (symmetrical point) region on the basis of the square body 130 And each of the wires 152 penetrating outwardly has a structure that is connected to the anchors which are fixing means 140 located at the lower side.

As described above, although a plurality of length adjusting means 150 can be installed on the body 130, it is preferable that the number of the length adjusting means 150 does not exceed 10 for simplification of the apparatus.

The control method of the length adjusting means 150 will be described with reference to FIGS. 1 to 3. FIG.

First, in order to set a reference for controlling the length adjusting means 150, the buoyancy of the coast reference point sign 100 itself excluding the fixing means 140 on the water surface is measured. Then, the wire 152 is wound through the winding means 156 so that a tension (basic tension value) corresponding to approximately 5% of the measured buoyancy value is caught by the wire 152. For reference, the buoyancy equation is as follows: B (buoyancy), p (fluid density), V (subdued volume), g (gravity acceleration)

In this case, when the length adjusting means 150 is composed of four length adjusting means 150 as shown in FIG. 1, the tension value applied to each wire 152 is a value obtained by dividing 5% of the buoyancy value by 4.

The reason why the tension (base tension value) corresponding to approximately 5% of the buoyancy value is caught by the wire 152 is that the base tension value is increased toward the bottom surface (sea bottom surface) So that the coast reference point sign 100 stays firmly at the installation position. In addition, even if the coastal reference point sign 100 is temporarily disengaged from the installation position, the user can return to the original installation position by pulling the same as the basic tension value.

It goes without saying that the basic tension value can be changed within a suitable range in consideration of various factors such as the weather condition (wave height, degree of wind, etc.) of the installation location, whether it is seawater or river water.

In this state, the lowering of the water surface causes the lowering of the buoyant body 134, so that the tension measured through the tension measuring sensor 154 becomes smaller than the basic tension value. Therefore, the information processing device 132 controls the winding of the wire 152 through the winding means 156 to maintain the basic tension value (refer to FIGs. 3A, 3B, and 3C)

Conversely, the rise of the water surface causes the lifting of the buoyant body 134, so that the tension measured through the tension measurement sensor 154 exceeds the basic tension value. Therefore, the information processing device 132 controls the wire 152 to be loosened through the winding means 156 to maintain the basic tension value (refer to Fig. 3 (c), (b), (a)

The coastal reference point sign 100 according to the present invention can provide accurate GCP data by maintaining the position of the coastal reference point signboard 100 according to the present invention without detaching from the installation position even at the tidal zone where the difference between the tide ranges is large as shown in FIG.

On the other hand, when the body 130 moves in one direction due to temporary wind or temporary currents in connection with the special control method, the tension of the two wires 152 in the direction of movement of the four wires 152 of FIG. 1 is temporarily . At this time, the information processing apparatus 132 may not operate the winding unit 156 even if it is increased beyond the basic tension value, in the case of temporary, in consideration of the change in the tension value measured repeatedly for a predetermined time.

By this control method, the operation of the winding means 156 is minimized, and the efficiency of the power of the coastal reference point sign 100 can be improved.

Referring to FIG. 4, a length adjusting unit 150 according to a modification of the present invention will now be described. That is, the length adjusting means 150 according to the modification may include a spiral spring 151, a shaft 153, a wire 155, a bracket 157, and the like.

The spiral spring 151, that is, the spiral spring refers to winding a strip of steel in a coil shape on a plane. The outer end of the spiral spring 151 is fixed to the bracket 157, which will be described later.

The elastic force at this time is adjusted so that the tension (basic tension value) corresponding to approximately 5% of the measured buoyancy value is caught by the wire 152, as described above.

The shaft 153 is a component that engages with one side (center end) of the helical spring so as to be provided with an elastic force by the helical spring 151, and has a cylindrical bar shape.

The wire 155 is an element for connecting the body 130 and the fixing means 140 and is formed in an actual shape as described above and can be wound or unwound on the shaft 153. If the wire 155 satisfies such a property, Anything is acceptable. However, since the wire 152 must be firmly connected between the fixing means 140 and the shaft 153, it is preferable to use a wire or nylon yarn having a small elongation and a large tensile strength.

One end of the wire 155 is engaged with one side of the shaft 153 and the other end is engaged with the anchor which is the fixing means 140.

The bracket 157 is a component that is installed on one side of the body 130 while fixing the shaft 153 so as to be rotatable and may be installed on the lower end surface of the body 130 as shown in FIG. Do. In this case, it is preferable that the housing 159, which is configured to surround the shaft 153, the helical spring 151, and the bracket 157, is tightly coupled to the body 130 to prevent corrosion of the apparatus.

The length adjusting means 150 according to the modified example may be implemented in a plurality of one or more as in the case of the length adjusting means 150 according to the aforementioned embodiment, and the description of the arrangement type based on the body 130, It will be omitted.

On the other hand, a speed clutch, which is a loosening preventing device applied to a vehicle seat belt or the like, may be further provided at one side of the rotating shaft 153 in order to prevent the body 130 from moving in one direction due to temporary winds or temporary currents have.

The length adjusting means 150 according to the modification example described above keeps the tension of the wire 155 constant depending on the mechanical elastic force of the helical spring 151 and the characteristic that the elastic force increases in proportion to the displacement It is preferable to apply the present invention to a river area or a lake area where the fluctuation of the depth of the water is small, rather than a place where a difference exists only in the tide interval such as the intertidal zone.

The coastal reference point sign 100 according to the above-described embodiment and the modification example has a mounting means 160 at the lower end of the body 130 so as to keep the state where the body 130 is separated from the floor surface when the body 130 is close to the floor surface .

This is to prevent the body 130 from being turned upside down by the protruding topography of the sea floor during the low altitude in the area where there is only the tide difference, so that the identification sheet 110 always faces upward. Preferably, the mounting means 160 is symmetrically disposed on the body 130 to support the lower end of the body 130 in a balanced manner.

A GPS receiver according to a modification will be described with reference to FIG.

In the embodiment of FIG. 1, the position information is obtained solely by using one GPS receiver 120 installed at the center of the identification sheet 110, while the modification is based on the center of the identification sheet 110 There is a difference in that two GPS receivers 120 are installed symmetrically at the same distance.

The reason why the two GPS receivers 120 are used is that it is possible to utilize the intermediate value of the line segment connecting the first and second position values (X, Y, Z values) Since it is possible to improve the accuracy of the position information more than when the receiver 120 is used.

Further, even if one GPS receiver 120 fails or is lost, position information can be continuously stored through the other one. At this time, however, a procedure for correcting the distance from the center of the identification sheet 110 is necessary.

Further, according to a modification of the present invention, four GPS receivers 120 may be installed symmetrically at the same distance with respect to the center of the identification sheet 110, which improves the accuracy of position information , To further enhance the convenience of the continuous storage of location information and the correction procedure for location information despite the loss or failure of some GPS receivers 120.

The other contents are the same as the contents of the GPS receiver 120 described above and will be omitted.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is obvious to those who have. Accordingly, such modifications or variations should not be individually understood from the technical spirit and viewpoint of the present invention, and modified embodiments should be included in the claims of the present invention.

100: coastal reference point sign for photogrammetry according to the present invention.
110: Identification table part 120: GPS receiver
130: body 132: information processing device
134: Buoyant body 140: Fixing means
150: length adjusting means 151: helical spring
152, 155: wire 153: shaft
154: tension measuring sensor 156: winding means
157: bracket 159: housing
160: Mounting means

Claims

An identification sheet portion formed on the top surface or the surface of the surface with a mark that can be identified in the upper portion in photometric measurement;
A GPS receiver installed at one side of the identification sheet and receiving position information from a satellite;
An information processing device coupled to a lower end of the identification sheet portion and storing and processing positional information received by the GPS receiver and having a buoyant body formed at a lower end thereof so as to float on a surface of the body;
Fixing means fixed to the bottom surface of the surface mounting position; And
And a length adjusting means for connecting the body and the fixing means so that the length of the body varies with the variation of the depth of the water to allow the body to always float without deviating from the installation position.

The method according to claim 1,
Wherein the length adjusting means comprises:
A wire whose one end is connected to the fixing means;
A tension measuring sensor installed at one side of the wire to measure a tension applied to the wire according to a variation in depth of water; And
And a winding means installed inside the body and connected to the other end of the wire, and winding means for winding or unwinding the wire according to the tension measured through the tension measuring sensor.

3. The method of claim 2,
Wherein the at least two length adjusting means are provided at positions symmetrical to each other with respect to the body.

The method according to claim 1,
Wherein the length adjusting means comprises:
Spiral spring;
A shaft engaged with one side of the helical spring to receive an elastic force by the helical spring;
A wire having one end engaged with one side of the shaft and wound or unwound on the shaft, and the other end coupled with the fixing means; And
And a bracket installed at one side of the body for fixing the shaft rotatably.

5. The method according to any one of claims 1 to 4,
Further comprising a mounting means formed at the lower end of the body so as to maintain the state of being separated from the bottom surface when the body is close to the bottom surface.

5. The method according to any one of claims 1 to 4,
The identification-
And a flat plate shape having a predetermined width.

The method according to claim 6,
The GPS receiver includes:
Wherein the identification mark is provided at the center of the identification sheet portion.

The method according to claim 6,
The GPS receiver includes:
Wherein the signboard is provided symmetrically at the same distance with respect to the center of the identification sheet portion.