• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.4
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• pp.319-325
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• 2007

In case of more than 50km baseline length, the correlation between receivers is reduced. Therefore, there are still some rooms for improvement of its positional accuracy. In this paper, the stochastic modeling of the ionospheric delay is applied and its effects are analyzed. The data processing has been performed by constructing a Kalman filter with states of positions, ambiguities, and the ionospheric delays in the double differenced mode. Considering the medium or long baseline length, both double differenced GPS phase and code observations are used as observables and LAMBDA has been applied to fix the ambiguities. The ionospheric delay is stochastically modeled by well-known 1st order Gauss-Markov process. And the correlation time and variation of 1st order Gauss-Markov process are calculated. This paper gives analyzed results of developed algorithm compared with commercial software and Bernese.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.1
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• pp.39-46
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• 2002

This paper shows what is point to be considered at that time in cadastral settlement surveying after declination analysis between GPS and traditional surveying at coordinate result of cadastral triangulation points and supplementary point in site selected deplaning of streets which is surveyed traditional surveying. In the case that coordinates of cadastral triangulation assistance points was decided by standard of the existing cadastral triangulation points that direction of the error vector is in opposition, authors could know all errors was reduced inside coordinate by error being offset each other through the results of study. The coordinates result of cadastral triangulation point by standard of the cadastral triangulation points reduces the deviation value through error that an intersection points was centered being offset each other but through the result that a tendency of errors occurrence is analyzed goniometrys, supplementary points that is close to cadastral triangulation assistance points was affected by error of cadastral triangulation assistance points.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.397-405
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• 2008

The position accuracy is primarily dependent on the satellite position and signal delay caused by several elements. To know the effect of the delay on the estimated positions, we simulated GPS raw data (RINEX) with GPS errors using Bernese ver5.0. GPS errors used in this paper are Ionospheric delay, Cycle slip, Troposphere, DOP and Random error. If the baseline is short, the position error according to TEC is not large, since the ionospheric delay effect can be removed by ion-free combination. However, if the baseline is long, 3 dimensional position error up to 10cm is occurred. The 3D position error of coordinates with cycle slip is hardly ever changed up to 60% of cycle slip. Because the simulated cycle slips are equally distributed on satellites, the positioning was not seriously affected by the cycle slip. Also, if percentage of cycle slip is 60%, three dimensional error is sharply increased over 1m. The position error is calculated by using the observation data (2 hours) which was selected by DOP less than 3. And its accuracy is more improved about $3{\sim}4cm$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.5
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• pp.555-563
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• 2009

When a mobile mapping system or a robot is equipped with only a GPS (Global Positioning System) and multiple stereo camera system, a transformation from a local camera coordinate system to GPS coordinate system is required to link camera poses and 3D data by V-SLAM (Vision based Simultaneous Localization And Mapping) to GIS data or remove the accumulation error of those camera poses. In order to satisfy the requirements, this paper proposed a novel method that calculates a camera rotation in the GPS coordinate system using the three pairs of camera positions by GPS and V-SLAM, respectively. The propose method is composed of four simple steps; 1) calculate a quaternion for two plane's normal vectors based on each three camera positions to be parallel, 2) transfer the three camera positions by V-SLAM with the calculated quaternion 3) calculate an additional quaternion for mapping the second or third point among the transferred positions to a camera position by GPS, and 4) determine a final quaternion by multiplying the two quaternions. The final quaternion can directly transfer from a local camera coordinate system to the GPS coordinate system. Additionally, an update of the 3D data of captured objects based on view angles from the object to cameras is proposed. This paper demonstrated the proposed method through a simulation and an experiment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.761-768
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• 2009

GPS data acquired at CORS are widely and rapidly used in many application such as information technology industries. In acquisition of GPS data the establishment of standards of reliability and tolerance error range is necessary. This standards is regarded to contain the requirements of selection of using softwares, precise and broadcast ephemeris, duration of data acquisition, and etc. This study focused to present above standards of tolerance error. In long baseline GPS observation network the RMSE analysed in this study resulted little change when data acquired in 6-hour duration, but the less observation duration resulted less accuracy. Especially in 3-hour observation the accuracy of GPS data decreased rapidly. After analyses of data accuracy in the same observation condition using different computer program between academic and commercial purpose software, the RMSE of academic software resulted less than 1cm compared to 3 to 10cm from commercial software. RMSE analysis between precise ephemeris and broadcast ephemeris resulted similar quantity. Therefore this study regarded to present the reliable establishment of standards of error which can be used in required accuracy in GPS data observation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.451-463
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• 2007

This paper describes issues of GPS network adjustment to determine coordinate sets of the $2^{nd}$ order national geodetic control points based on the Korean Geodetic Datum (KGD2002) which has been newly adopted in 2003, After outlining theoretical background of the GPS network processing, the adjustment procedure applied for this project is detailed. Throughout performing a series of minimally constrained adjustments, some outliers have been removed and magnitude of absolute and relative error for a stochastic modeling has been determined as 4mm+0.4ppm and 8mm+0.8ppm in the horizontal and vertical component, respectively. The over constrained adjustment by fixing the $1^{st}$ order control points was performed to derive final solution, indicating that the accuracy of the estimated coordinates was 2cm and 4cm in the horizontal and vertical component.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.3 s.21
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• pp.107-114
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• 2002

The cadastral surveying is essential for the effective management of a country, the D/B building of NGIS. Many of GPS applications require a positioning accuracy of several centimeters for rover in real-times. But, to achieve higher positioning accuracies in real-time, the double differencing technique should be implemented using carrier phase data. Corrected observations at the reference station can be transmitted and used to form double difference observations at the rover using a data link. In this study, the area accuracy of cadastral survey using the RTK GPS will be assessed, and will produce area of parcel of land. As the result of comparison among area by TS, planer surveying and RTK GPS. parcels-register for site is analyzed by this data. The results show that mean error of area calculated min. $2.42m^{2}{\sim}\;max.\;13.69m^{2}$ and RMSE calculated min. $0.00329\;{\sim}\;max.\;0.01846$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.4
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• pp.293-299
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• 2003

In the future, the design of road should be convenient in using of high-technology information and it needs the design of alignment that is able to make the maximum vehicles inducement function appropriated for CNS(Car Navigation System). So it needs to analysis appropriately the alignment of road for the improvement design of road which is established and to make the design of road and the coordinate of the main points. Therefore, this research had acquired the road data by RTK-GPS to accurate the analysis of road alignment and compared with Total Station. As the result, we could acquire the design source of the road alignment using RTK-GPS. Also, it was estimated the accuracy after comparing the design with RTK-GPS coordinates. We made an analysis of the degree of slant or the ups and downs of surface. We made an analysis of three dimensional visual information which was included in GSIS concept and estimated the accuracy. Finally, we analyzed the earth volume calculation by comparing with Total Station.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.207-213
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• 2007

For several years, although the demand of high accuracy kinematic positing using multiple bases has been increased, most of the commercial GPS processing softwares can provide the single-baseline solutions only. Thus, we studied the methods to improve the accuracy of the kinematic positioning using the network configuration based on the several single-baseline solutions. As discussed in this study, the positioning accuracy as well as the network stability is improved by introducing the geodetic network adjustment theories into the kinematic positioning application. Three different methods to remove the rank-deficiency, RLESS, BLIMPBE and SCLESS, are analyzed in this study. The 3D RMS error has been improved from 3.5cm(max) to 2.1cm using the network-based kinematic positioning, and it is desired to choose BLIMPBE and SCLESS depending on the accuracy of the base stations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.191-198
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• 2007

According to the survey data during the Japanese Occupation Period, the length of South Korea's coastline is about 11,542km, including the coastlines of mainland and islands. To accurately revise/renew this coastline data through site survey, it will cost great money and time. Also, various development projects such as reclamation works on public waters, constructions of ports/harbors, etc. This paper used aerial photographs, satellite image data and GPS survey data with certain intervals to monitor the change in coastal areas of Songieong, Haeundae, Kwanganri, Songdo and Dadaepo. The local area subjected for this research was limited to areas near Busan. The specific contents of this research include. Launching qualitative/time series analyses on the change of coastal areas using aerial photographs, satellite image data and RTK-GPS surveys.