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Analysis of the Effect of Tropospheric Delay on Orthometric Height Determination at High Mountain
어수창,이석배 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11
The purpose of this study is to precisely determine the orthometric height considering tropospheric delay at the top of the mountain where the height difference with reference ground surface is large. So, GNSS surveying was carried out at Cheonwangbong on Mount Jiri to determine the orthometric height, and GNSS data were processed by both DGNSS and PPP methods to determine ellipsoidal height using Bernese version 5.0 software. In this process, KNGeoid14 Korean geoid model was used and the effects of troposphere delay on the coordinates and orthometric height were analyzed. The study results showed that the tropospheric delay was reduced by 3.04 cm with every 100 m increase of the ellipsoidal height. The orthometric height and RMSE determined by the DGNSS method were found to be 1915.4596 m and 0.0520 m, respectively, and the orthometric height and RMSE determined by the PPP method were found to be 1915.4059 m and 0.0527 m, respectively. So, the difference between the DGNSS method and the PPP method when tropospheric corrections were applied showed a difference of 5.37 cm in orthometric height. And, the results also showed that the difference in whether or not the tropospheric delay model was applied in the calculation of the orthometric height was 1.53 cm in the same DGNSS method.
Evaluation of Global and Regional Geoid Models in South Korea by Using Terrestrial and GNSS Data
이석배,어수창,서동용 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5
In this study, 96 bench marks and unified control points across South Korea were selected as GPS/Leveling stations, GPS surveying was conducted in the Network-RTK (VRS) method and the results were utilized to calculate geometric geoidal heights. These geometric geoidal heights were utilized in the evaluation of the geoid models comprising global gravity field models, such as EGM2008 and EIGEN-6C4, and South Korean geoid models, such as KNGoeid13 and KNGeoid14. In addition, geoid model KNGeoid14, which was found to have the highest accuracy and precision through the evaluation, was utilized to calculate GPS derived orthometric heights, and the results were evaluated to review the possibility of orthometric height surveys using the GPS/ Geoid method. As for the results of the study, in the evaluation of the global gravity field models, the standard deviations of EGM2008 and EIGEN-6C4 were shown to be almost the same as the values were 7.0 cm and 7.1 cm respectively, and geoid model KNGeoid14 was found to have been improved compared to KNGeoid13 as its RMS and standard deviation were shown to be smaller than those of KNGeoid13. In addition, differences in the orthometric height values of 96 points derived in the GPS/Geoid method were analysed using geoid model KNGeoid14, and, in the results, the average error was shown to be 3.9 cm and the standard deviations was shown to be 5.2 cm so that the possibility of utilization of the GPS/Geoid method in orthometric height surveys with the decimeter accuracy could be identified.
이석배,어수창 한국국토정보공사 2018 지적과 국토정보 Vol.48 No.2
The purpose of this study is to determine the precise height in mountainous areas of South Korea and Jiri mountain area was selected as a test bed for the study. Gravity observation and GNSS surveying were performed for 44 BM(Benchmark) points in the test bed and calculate the height and the height correction. In the calculation, the dynamic correction amount, the orthometric correction amount and the normal correction amount were calculated, and the dynamic height and orthometric height and the normal height were calculated considering each correction amount. The results showed that the difference between normal gravity and observed gravity and also the difference between orthometric correction and the normal correction. In addition, the results of the comparison of the present official BM height and the computed orthometric height in this study show that Korean height system should be shifted from the normal orthometric height system to the orthometric height system. Because the difference between the orthometric correction and the normal correction within the test bed indicated a distribution of at a minimum of -234.41 mm up to 196.925 mm, and the difference between the present official BM height and the calculated orthometric height were distributed from –0.121m to 0.011 m . 본 연구는 우리나라 산악지에서의 정밀표고결정을 목적으로, 지리산 지역을 테스트베드로 선정하고 테스트베드 내의 44점의 수준점에 대하여 중력측정 및 GNSS 관측을 실시하고 측정결과를 바탕으로 표고보정량과 표고를 계산하고 연구한 논문이다. 계산에 있어서는 역학보정량과 정사보정량 및 정규보정량을 계산하였으며 이를 적용한 역학고와 정표고 그리고 정규고를 계산하였다. 연구결과 정규중력과 실측중력의 차이를 규명해 내었고 또 정사보정량과 정규보정량의 차이를 규명할 수 있었다. 또한 정규정표고 체계를 유지하고 있는 현재의 수준점 고시성과와 본 연구에서 계산된 정표고 값을 비교한 결과는 우리나라의 수준점 성과체계가 정규정표고 체계에서 정표고 체계로의 전환하여야 함을 보여주고 있었다. 테스트베드내에서 정사보정량과 정규보정량의 차이는 최소 –234.41 mm에서 최대 196.925 mm의 분포를 나타냈고, 현재의 수준점 고시성과와 본 연구에서 계산된 정표고와의 차이는 –0.121 m에서 0.011 m의 차이를 보여주는 것을 알 수 있었다.
이석배,어수창 대한공간정보학회 2016 대한공간정보학회지 Vol.24 No.2
After the ‘Guidelines for the preservation of digital heritage’ were published by UNESCO, interests in the fabrication of digital cultural heritage have been increasing throughout the world. The present study was intended to fabricate digital cultural heritages for existing culturalpropertiesusing the reverse engineering technology and obtain two‐dimensional drawings. Jinju Castle Gongbukmun, which is a cultural property, was selected as a study subject and 3D modeling of Jinju Castle Gongbukmun was conducted by implementing 3D scanning and processing the point cloud data. Using the Gongbukmun 3D model (3D‐Gongbukmun) made as such, requirements as a digital heritage were reviewed and 2D drawings of Gongbukmun such as front views, ground plans, and side views could be prepared.