• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.423-427
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• 2010

현재 GPS/INS 운영 방법은 일정한 범위 내에 GPS 지상기준국을 설치하도록 되어있다. 그러나 촬영지역이 넓을 경우나 작업의 우선순위 등에 따라 지상기준국의 운영이 곤란한 상황이 발생할 수 있으며, 작업자의 실수, 수신기의 오류 등으로 지상기준국을 항상 안정적으로 운영하기 어렵다. 이에 본 연구에서는 국토지리정보원의 GPS 상시관측소를 활용하여 항공레이저측량 원시자료를 구축하고, 지상 기준국을 사용한 결과와의 비교를 통해 기준국이 항공레이저측량 결과에 미치는 영향을 분석하고자하였다.

• Korean Journal of Geomatics
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• v.2 no.2
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• pp.99-105
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• 2002

The accuracy of the Digital Photologging System, designed for the construction of the road Facility Database, highly depends on the positions and attitudes of the cameras from GPS/INS integration. In this paper, the development of a loosely coupled GPS/INS is presented. The performance of the system is verified through a simulation as well as a real test data processing. Since the IMU used in this study shows large systematic errors, the possible accuracy of the positions and attitudes of this low-performance IMU when combined with precise GPS positions are assigned. Currently, the integrated system shows the positional accuracy better than 5cm in real data processing. Although the accuracy of attitude based on real test could not be assigned at this time, it is expected that better than 0.5 degrees and 1.8 degrees for horizontal and down component are achievable according to the simulation result.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.103-106
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• 2004

Nowadays it is necessary to manage the road system effectively because of the explosive increment of vehicle and goods. To resolve this problems through the fast upgrade of information about position and time of moving vehicle, the combined navigation system using GPS and complementary navigation system, i.e. INS, DR, etc. has been used. Although GPS is popular for the vehicle navigation system, this is not useful for the kinematic positioning of the vehicles in the urban canyon because of its few satellites. Therefore, this study deals with the kinematic positioning of the vehicles with GPS CORS to GPS navigation. For this, first the static single point positioning of GPS and GPS for reference station was performed to evaluate the accuracy of GPS positioning. Next, in the post-processed, the DGPS (Differential GPS) was performed for the kinematic positioning of the vehicles. So, it is expected that GPS CORS can be applicable to the control of traffic flow, the effective management of road system, and the development of ITS and it is regarded that the combined navigation system of vehicles with GPS, INS, and DR, etc. should be studied constantly.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.263-268
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• 2004

GPS/INS에 의한 항공사진측량을 이용하려면 사진촬영과 동시에 획득한 외부표정요소의 결과를 도화ㆍ편집 작업에 실제로 적용해 보아야 한다. 도화성과의 검증작업은 GPS/INS의 결과를 이용하여 수치지도의 제작시 가장 중요한 공정에 해당한다. 이를 위하여 기존 AT성과에 의하여 제작된 해석도화원도를 기준으로 본 연구에서 제시한 AT 성과별, 도화기별, 표정방식별로 수행한 도화결과를 비교하였다. AT 성과와 표정방법에 상관없이 해석도화와 수치도화의 평면과 표고의 오차를 비교하여 보면, 해석도화가 수치도화보다 우수한 결과를 보여주며, 또한 평면오차가 표고오차보다 더 크게 나타남을 알 수 있었다. GPS/INS AT의 Direct 표정의 경우 InDirect 표정방법에 비해 3배 이상의 오차가 발생하였으나 모든 경우의 결과가 허용오차를 충족하고 있으므로 축척 1:5000에서는 GPS/INS AT를 이용한 표정과 도화작업은 매우 효율적으로 수행될 수 있음을 알 수 있었다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.5
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• pp.479-484
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• 2010

In the airborne laser survey with GPS/INS, based on kinematic, the installation and operation of GPS base stations is necessary to allow three-dimensional location coordinates to be obtained quickly and precisely. However, in many cases, GPS base stations operate under difficult conditions. In this paper, we investigate the substitutability of continuously operating reference stations (CORS) for base stations, and we examine the influence of the distance between aircraft GPS and CORS on the Z-value. The results of our study demonstrate that, if the performance of GPS base stations within regulation distance is replaced with that of CORS, sufficient accuracy is guaranteed. Moreover, the performance of CORS beyond regulation distance is fairly good.

• Korean Journal of Geomatics
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• v.3 no.2
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• pp.129-140
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• 2004

This paper addresses solutions th the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as th cumulative-sun (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.677-685
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• 2011

In order to enhance public transportation and to maintain information credibility, improvement of accuracy regarding route and positional information of public transport is very significant. There have been a variety of methods using GPS to measure accuracy of location-based services. However, the researches of evaluation regarding kinematic position of linear objects measured by vehicle/kinematic GPS are still insufficient. That's why our paper aims to suggest method of evaluation accuracy on a real-time bus route surveyed by GPS by SBM(Single Buffering Method). To make it come true, we compared the findings on the static and dynamic positioning by using PP(Point Positioning), DGPS and GPS/INS integrated systems and analyzed the accuracy and error effects among them, focusing on Anyang city. Consequently, we can find out that in case of P.P. comparing positioning accuracy between RTK DGPS and GPS/INS, both of them have survey result within a margin of error of 5m. More importantly, we can evaluate positional accuracy of each GPS system based on the work provision of a public survey such as error for P.P.(14.5m, 18.1m), DGPS(16.9m, 18.5m), and GPS/INS(18.4m, 18.5m). We are expecting that proposed method in our paper can be utilized in a wide range of categories such as feasibility testing of GPS field survey and high accuracy of positioning for Bus Information System.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.225-234
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• 2009

Real-time Aerial Monitoring System (RAMS) is to perform the rapid mapping in an emergency situation so that the geoinformation such as orthophoto and/or Digital Elevation Model is constructed in near real time. In this system, the GPS/INS plays an very important role in providing the position as well as the attitude information. Therefore, in this study, the performance of an IMU sensor which is supposed to be installed on board the RAMS is evaluated. And the integration algorithm of GPS/INS are tested with simulated dataset to find out which is more appropriate in real time mapping. According to the static and kinematic results, the sensor shows the position error of 3$\sim$4m and 2$\sim$3m, respectively. Also, it was verified that the sensor performs better on the attitude when the magnetic field sensor are used in the Aerospace mode. In the comparison of EKF and UKF, the overall performances shows not much differences in straight as well as in curved trajectory. However, the calculation time in EKF was appeared about 25 times faster than that of UKF, thus EKF seems to be the better selection in RAMS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.359-366
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• 2005

Airborne LiDAR integrated with on-board GPS/INS and scanning technology is a state-of the-art system for direct 3D geo-spatial data acquisition. In this study, LiDAR data were calibrated using ground points in calibration site for the higher system accuracy. The accuracy results are ${\pm}15{\sim}30\;cm$ in horizontal and ${\pm}15\;cm$ in vertical. The results show that LiDAR system has capability for precise DEM and contour generation, 3D urban modeling and engineering design.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.249-254
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• 2006

Aerial photo process with digital camera has some benefits. It is fast and simple by digital way in comparison with aerial photo based on film. Also it works with GPS/INS device to do direct geo-referencing, In this study, AT result from using direct exterior factors, exterior factors extracting from GPS/INS data and digital map and GCP is produced. In base on it, ortho images are produced and compared with surveying data.