• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.63-64
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• 2002

GPS 시스템을 사용하면 전세계에 걸쳐 언제든지 수$\pm$10m 이내의 오차범위에서 위치를 측정할 수 있다. 이보다 더 정밀한 위치가 필요할 경우에는 Differential GPS (DGPS)방식을 자주 사용한다. DGPS방식은 실시간 처리(Real time kinemetic: RTK)와 후처리(post-processing)방식으로 나눌 수 있다. 측위정도는 정적 후처리방식이 동적 후처방식이 보다 높은 것이 일반적이다. (중략)

• 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.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.275-281
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• 2004

Geodetic surveying using precise GPS equipment are used without analysis with a statistical verification of GPS observed value and it was preformed by necessity to integration projection of digital topographic map and nautical Chart for integration geographic information system construction. The purpose of this study proposes method that improve accuracy of GPS observed value and direction that integrally manage digital topographic map and electronic nautical chart in analyzing the boundary line error between digital topographic map and nautical Chart. For improvement of the precision of GPS observed value, the author studied precision-analysis of GPS observed value by geometric strength and variance factor in 3 control points used in GPS network adjustment. This study compare the whole boundary point error When producing EDM measurement using this GPS observation results and setting digital topographic map and nautical chart by these boundary.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1043-1044
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• 2009

본 논문에서는 GPS 편차 정보를 이용하여 도로 네트워크 지도 제작시 불가피하게 발생하는 오차를 탐지하는 기법을 제안한다. 제안된 기법은 수십에서 수백 킬로미터 범위에 위치한 노드들이 공통적인 GPS오차를 겪는다는 점에 착안하고 있으며 각 도로 네트워크의 차량들이 동시간에 보고하는 위치 좌표를 이용하여 맵 매칭을 수행한 후 해당 시간스탬프의 오차를 계산한다. 이 오차를 이용하여 각 위치 좌표들를 보정한 후 다시 맵 매칭을 수행하여 맵 매칭의 오류가 한계치 이하라면 보고된 위치에 해당하는 도로들은 정확하게 플롯되어 있음을 알 수 있다. 이와 같은 통계들이 오랜 시간동안 쌓인다면 별도의 장비나 통신채널을 사용하지 않고 소프트웨어만으로 도로망 지도의 정확성을 검증할 수 있다.

• Spatial Information Research
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• v.12 no.4 s.31
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• pp.371-382
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• 2004

Continuously Operating Reference Stations (CORS) provides GPS measurements to support high accuracy CPS positioning. The CORS improves GPS positioning productivity by eliminating the requirement for GPS users to operate two receivers. Previously, this is achieved by providing data from CORS to users in post-mission mode. However, the efficiency of the CORS will be maximized by upgrading it in real-time operation using RTK-GPS surveying because users can obtain centimeter-level accuracy in real-time without operating their own reference stations. In this research, authors extracted the arbitrary point's coordinate which is using GPS CORS data, now served in RINEX FORMAT via Internet, with observation network of the existing triangulation and GPS CORS data. And then, RTK GPS was performed with this arbitrary point as reference station.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.36-43
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• 2009

In this study, the impact of the covariance between the baselines on the network-based GPS positioning is analyzed. For the analysis, the multi-baseline solutions with properly modeled covariance between the baselines and the combined solutions from the single-baseline solutions are obtained, respectively. Then, the accuracies of both solutions are evaluated in terms of coordinate residuals, i.e., the differences between the positioning solutions and the published stations' coordinates. The results indicate that the positioning accuracy in static mode depends much on the geometry of GPS satellites rather than the proper modeling of covariance between the baselines. Also, slight but negligible improvement in positioning accuracy is observed in static solutions. Therefore, one may use combined solutions as an alternative to multi-baseline solutions for the network-based GPS positioning. However, multi-baseline solution with properly modeled covariance between the baselines is recommended to use especially for the applications to detect very small displacement, i.e., deformation of the building or bridge.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.275-284
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• 2007

For the application to the numerical weather prediction (NWP) in active service, it is necessary to ensure that the GPS precipitable water vapor (PWV) data has less than one hour latency and three millimeter accuracy. The comparison and the verification between the daily products from GPS measurement by using the IGS final ephemeris and the conventional meteorological observation has been done in domestic researches. In case of using IGS final ephemeris, GPS measurements can be only post processed in daily basis in three weeks after the observation. Thus this method cannot be applied to any near real-time data processing. In this paper, a GPS data processing method to produce the PWV output with three mm accuracy and one hour latency for the data assimilation in NWP has been planned. For our new data processing strategy, IGS ultra-rapid ephemeris and the sliding window technique are applied. And the results from the new strategy has been verified. The GPS measurements during the first 10 days of January, April, July and October were processed. The results from the observations at Sokcho, where the GPS and radiosonde were collocated, were compared. As the results, a data processing strategy with 0.8 mm of mean bias and 1.7 mm of standard deviation in three minutes forty-three seconds has been established.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.221-225
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• 1995

Unauthorized users cant acquire and enough accuracy in applications of the navigation or geodesy by the single GPS positioning technique because of the measurement errors and US DoDs intentional errors. The solution of these restrictions is the Dgps technique that is to eliminate the common errors between the reference station and the desired point and can achieve a high accuracy. DGPS postprocessing system is implemented by using the offset distances between the known position of a reference station and the position obtained from GPS satellite data. The preliminary experiments include static tests and a dynamic test of cruising a ship.

• 한국지형공간정보학회:학술대회논문집
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• 2002.03a
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• pp.3-8
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• 2002

현장에서 GPS 측량을 하였을 때 그 측량성과를 처리할 수 있는 장소로 이동을 한 후 측량결과를 확인해야 하며, 만약 측량이 잘못 되었다는 결과가 나오면 재 측량을 해야하는 상황이 발생한다. 이와 같은 경우가 생기면, 계획했던 시간과 경비의 소요가 더 많아지게 되므로 작업의 손실이 생기는 것은 당연하다. 본 연구에서는 이러한 작업의 손실을 최소화하기 위한 방법으로 GPS 측량을 한 현장에서 바로 측량성과의 가용성 여부를 결정해 줄 수 있는 소프트웨어 개발을 연구하였다.

• 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.