• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.311-318
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• 2011

On March 11, 2011, an 9.0-magnitude earthquake occurred near the northeastem coast Japanese. It was the largest earthquake that hit Japan since the beginning of modern seismometry. The earthquake occurred 179km east of the Sendai, Miyagi Prefecture, leaving about 27,000 of people confirmed dead, injured or missing due to the earthquake and tsunami. In this study, crustal Deformation in Mizusawa, Tsukuba and Usuda station were calculated based on GPS data in IGS station of Japan. The observation data were processed by precise point positioning and relative-positioning method using on-line GPS data processing services and a high precision scientific GPS/GLONASS data processing software. The coseismic displacements in IGS stations before and after the earthquake were analyzed using kinematic precise point positioning method, and the crustal deformation of the areas before and after the earthquake were precisely calculated using the relative-positioning method. The results of the study calculated precise coordination that the RMSE is maximum ${\pm}0.003m$, respectively and showed that Mizusawa station moved 2.6m southeast by the earthquake.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.2 s.16
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• pp.101-108
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• 2000

Kinematic GPS surveying which can be obtained many three-dimensional topographical informations through a short-time measurement is being utilized mainly in the short base line of a few km and below The coordinate for the long base line depends on Static GPS surveying But it needs long time measurement. Therefore, the method which can decide a position of the long base line for a short time is being needed. To examine a possibility of an efficient use of kinematic GPS surveying of the long base line, this research has analysed an accuracy of the base line by static GPS surveying according to baseline distance, ephmeris, and observation time. As the results of research, I could see that accuracy was very low in case of the occurrence of cycle slip. When we use of precise ephmeris, we obtained 1ppm and less of accuracy with one-minute kinematic GPS surveying within 70km. If a lot of studies about the long baseline kinematic GPS surveying are processed, a topographical information necessary for each kind of construction field including land development could be utilized more efficiently.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.83-90
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• 2002

Control point survey by GPS can save labor and time and can obtain result of high accuracy, but if excessive error is contained to Control point that is used to GPS relative positioning, the error that has influence on new point is propagated to various configuration. therefore poor triangulation points that are caused by careless management are existed, a product of the triangulation points still are in many case. In order to select new point, this study carried out error-analysis of surrounding-control-points and performed selective process of control point. The propriety parts of control points that are used to verify precision is identified by means of comparing existing product with or GPS product about some control points after directly observe each baseline by using EDM. As the error is analyzed by static positioning the optimum control point is selected, the precision of survey data by EDM is improved than GPS data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.301-309
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• 1999

Real-time kinematic (RTK) GPS surveying which allows centimeter level accuracy of three-dimensional coordinates without post-processing has become recognized as a major advance in GPS technology. Employing On-The-Fly initialization technique, the RTK system can escape from cycle slip problems that have affected as a main obstacle factor in traditional kinematic and static approaches. The objective of this research was to evaluate accuracy and effectiveness of the RTK-GPS surveying. First, the continuous RTK observation of a base line was conducted for the purpose of finding out the repeatability of the RTK surveying and the results which were then compared against results from static surveying showed RMS errors of $\pm{3mm}\;and\;\pm{13mm}$ for their respective horizontal and vertical components. On a test network of 30 stations covering the small area, the results of RTK testing were compared against those from not only post-processing kinematic and rapid-static surveyings but conventional surveyings and also the efficiency of RTK were analyzed. In addition, geoid heights which were derived by combination of GPS and spirit leveling about all of the points within the network were compared against those derived by the PNU95 and EGM96 models respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.1
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• pp.29-39
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• 1997

The need of transformation parameters from local geodetic datums to a geocentric coordinate system is becoming more common, with the increasing application of satellite positioning techniques to LIS/GIS survey with cadastral management. In this paper, the national transformation parameters between the Korean geodetic coordinates which is based on the Bessel 1841 ellipsoid and the WGS84 ellipsoid are determined by the least square methods with weighted parameter constraints. Three-dimensional geocentric coordinates are based on GPS observation at 31 stations in the geodetic network, the datum parameters are computed within a standard deviation of less than 1 meter. In South Korea, the national transformation parameters with Bessel geoid-heights are useful for GPS baseline processing and for middle-scale map/database transformation.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1077-1085
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• 2016

In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of $1{\times}1cm^2$ was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.195-202
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• 1998

In this study, we utilized various type of GPS observation measurements to get a camera projection center of the aerial triangulation and consequently to determine which type is acceptable. For the accuracy and the error analysis, comparison between a projection center from the conventional model adjustment and the result determined by the kinematic DGPS positioning which is fitted to the conventional model adjustment using 3D conformal transformation method has been made. The camera projection center is located within a $\pm{2m}$ for C/A code range measurements, $\pm{14cm}$ for L1 phase measurements and $\pm{10cm}$ for L1/L2 phase measurements with $1\sigma$. In this way, the accuracy of the camera projection center by the bundle block adjustment can be predicted.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.333-335
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• 2010

Global warming gas caused an increase in a direct and indirect problems like the rising sea level, seawater overflowing and a coastal flooding. The loss and damage of the republic of korea are increasing because of the rising sea level. As a result, It is necessary to establish the foundation of the monitoring of the sea level changes for the flooding prevention. A new measurement technique is developed using GPS equipped ship to make up for the spatial-temporal and economical problems by this study. We compared the data using GPS with the value for height of the tide. And we corrected the errors using the more accurate data that we studied. In addition to we studied that the corrected value had statistical significance and similarity compared with the observed value using GPS. The following studies also performed : When the observed value of tide by a tide observatory and by using GPS are applied to sounding ; How the values of the water depth are being, and if the values are similar, whether the observed value of tide using GPS is valid or not.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.2
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• pp.215-222
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• 2002

As the GPS signals propagate from the GPS satellites to the receivers on the ground, they are delayed by the atmosphere. The tropospheric delay consists of two components. The hydrostatic (or "dry") component that is dependent on the dry air gasses in the atmosphere and accounts for approximately 90% of the delay. And the "wet" component that depends on the moisture content of the atmosphere and accounts for the remaining effect of the delay. The Zenith Hydrostatic Delay (ZHD) can be calculated from the local surface pressure. The Total Zenith Delay (TZD) will be estimated and the wet component extracted later. Integrated water Vapor (IWV) gives the total amount of water vapor that a signal from the zenith direction would encounter. Precipitable Water Vapor (PWV) is the IWV scaled by the density of water. The quality of this PWV has been verified by comparison with radiosonde data(at Osan). We processed data for JULY 2 and JULY 14, 1999 from four stations(Cheju, Kwangju, Suwon, Daegu). We found the coincidence between PWV of the estimations using GPS and PWV of pressing the radiosonde data. The average of the difference between PWV using GPS and PWV using radiosonde was 3.77 mm(Std. ＝ $\pm$0.013 mm) and 2.70 mm(Std. = $\pm$0.0011 mm) at Suwon & Kwangju.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.455-458
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• 2006

The Real Time Kinematic (RTK) technique is the most productive and accurate GPS positioning method today, as it can be determinate position within few centimeters instantly. This method is widely used for applications such as surveying, structure monitoring and machine guidance etc. In order to perform RTK processing for large scale systems (i.e. precise vehicle monitoring with many rovers), many expensive RTK receivers and same number of bidirectional communication units have to be installed to collect observation data communicate with the reference site and monitor its RTK solutions. Moreover, if applications require remote control or apply sensing instruments, we have to install computers at each rover. To limit expense and complexity of system management with a large number of rovers, we have developed server based RTK processing platform to share RTK function for all rovers. The system can be process many GPS stations with a single personal computer. we have also developed a specialized dual frequency GPS receiver unit without on-board RTK processing capability to reduce receiver cost in order to demonstrate the advantage of our server based RTK platform. This paper describes the concept of our server based RTK platform and specialized GPS receiver unit with existing applications in Japan.