정밀 GPS 해석 S/W GMAIT/GLOBK를 활용한 TBM의 3차원 위치 결정

Determination of 3-D Positions on TBMs Using the Precise GPS Data analysis SW, GAMIT/GLOBK

In this study, we determined the precise coordinates of TBMs (Tidal Bench Marks), which used as the national reference points in coastal area of Korea, using a GPS data analysis SW for the academic and scientific applications, GAMIT/GLOBK. For accurate 3-D positioning of TBM locations, we performed the GPS point surveying according to the national surveying policy and also acquired the GPS data for 48 TBMs located in the western and southern coastal part of Korea. Considering the results of baseline analysis to each observation session obtained from GAMIT module, the baseline analysis was realized to be done precisely because the values of Normalized RMS (NRMS) were mostly less than ±0.20 mm. Before the network adjustment using GLOBK module, we evaluated the suitability of observations for each session by applying the chi-squared test ( χ² test) to the degree of freedom in observed session. An overall distributions of χ² test were less than 1.0 for all sessions, and the statistical of χ ² test showed the average, 0.267 with minimum and maximum value, 0.063 and 0.653, respectively. Finally, we analyzed the network adjustment for 48 TBMs to reduce the residuals of baseline analysis on each point by connecting with 42 permanent GPS stations in Korea. In the network adjustment procedure, we set up the weighted values of each permanent station to be allocated between 0.9 and 1.14, and also removed the observed points having residual exceeds 4-times of standard deviation (4 σ ).