• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.3
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• pp.249-258
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• 2012

In this study, the epoch adjustment model was developed to correct GPS precise point positioning result to be suitable for the current geodetic datum of Korea which is tied at past epoch statically. The model is based on the formula describing crustal movements, and the formula is composed of several parameters. To determine the parameters, the data gathered at 14 permanent GPS stations for 10 years, from 2000 to 2011, were processed using GIPSY-OASIS II. It was possible to determine the position of permanent GPS stations with an error range of 16mm and the position of check points with an error range of 12mm by appling the model to GPS precise point positioning result. It is considered that more precise model could be calculated by using GPS data of more permanent GPS stations.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.105-109
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• 2012

In this paper, we developed an adoptable deployment method to the transmitting antennas of a ground based GPS system for aircraft. Aircraft generally uses satellite providing GPS signals for accurate position information, but transfers to ground based GPS signals time to time due to jamming signals or bad weather. The position accuracy of the ground based GPS system is highly dependent on the number and position of the GPS transmitting antennas. In this research, we found an algorism to predict the DOP due to the location of the GPS transmitting antennas and had an accurate DOP 2.5 area into 3-dimension from 0 to 10 km by 12 transmitting antennas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.2
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• pp.155-161
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• 1994

Accurate positioning method using low cost GPS modules is proposed, which use the technique of differential GPS. DGPS experiments have been made using two coarse-acquisition (C/A) code GPS modules. Position accuracy of better than 5 m was obtained for position dilution of precision (PDOP) of 2-3 and that of better than 10 m after filtering was obtained for PDOP of about 9 in a local area. Static DGPS experiments were performed at Kookmin university with the DGPS correction data of KRISS reference station at Taejon. The distance between two stations is about 140 km. The results show that precision of the position is about 10 m (2 drms), which is ten times better than the results with the GPS module alone. Accuracy of about 10 meters can be obtained in near real time by the DGPS service with a reference station in our country.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.51-57
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• 2002

GPS proved to very practical in the application of geodesy and surveying such Civil Engineering, control point surveying and the deformation surveying o( structure, but the accuracy of static GPS positioning is degraded at the sites which the visible satellites of GPS are less than 4, i.e. the urban area covered with the high building and the industrial zone. Thus, the combined GPS/GLONASS system was introduced to acquire the high accuracy of static positioning by a few satellites. So the combined GPS/GLONASS system show the good results at the sites which the accuracy of positioning is degraded due to few satellites, the cutoff of signal, and multipath in the urban area.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.65-72
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• 2010

In this study, the performances of a medium grade IMU which is aimed for Mobile Mapping System and a low grade IMU for pedestrian navigation are analyzed through simulations under GPS signal blockage. In addition, an analysis on the accuracy improvement of barometer, electronic compass, or multi-sensor(combination of barometer and electronic compass) to correct medium grade or low grade IMU errors in the situation of GPS signal blockage is performed. With the medium grade IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 5m when the block time is over 30 seconds. When we correct IMU with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 60 seconds. In addition, barometer is more effective than the electronic compass when they are combined. In case of low grade IMU like MEMS IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 20m when the block time is over 15 seconds. When we correct INS with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 15 seconds in simulation results. On the contrary to medium grade IMU, electronic compass is more effective than the barometer in case of low velocity such as pedestrian navigation. It is expected that the analysis suggested a method to decrease position or attitude error using aided sensor integration when MMS or pedestrian navigation is operated under 1he environment of GPS signal blockage.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.259-268
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• 2006

The use of GPS receiver at outer space becomes common in low earth orbit. Recently most of satellites use GPS receiver as navigation solution for finding satellite position. However, the accuracy of navigation solution acquiring directly from GPS receiver is not enough in satellite application such as map generation. Post-processing concepts such as Precise Orbit Determination (POD) are recently applied to satellite data processing to improve satellite position accuracy. The POD uses raw measurement data instead of navigation solution of GPS receiver. The performance of raw measurement data depends on raw measurement data accuracy and tracking loop algorithm of GPS receiver. In this paper, a method for evaluating performance of raw measurement data is suggested. Test environment and procedure of the low earth orbit satellite acquiring for navigation solution of GPS receiver and navigation solution of POD are described. In addition, accuracy on navigation solution of GPS receiver, raw measurement data, and navigation solution of POD are analyzed. The proposed method can be applicable to general low earth orbit satellite.

• Spatial Information Research
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• v.14 no.2 s.37
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• pp.211-221
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• 2006

GLONASS(Global NAvigation Satellite System) using the satellite information on 19,100km altitude supplies the location information similar method with GPS. Therefore, many researches study in combination GPS and GLONASS. This research compares with deciding coordination of one unit parcel using RTK-GPS and RTK-GPS/CLONASS. Then we examine the possibility of RTK-GPS/GLONASS for determining parcel coordinate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.571-578
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• 2009

This paper shows the results of the comparative analysis of differences and similarities between GPS-based and RFID-based traffic information collection systems for testing the applicability of RFID system in urban street settings in Jeju island, Korea. For this, we reviewed both traffic information collection systems in terms of accuracy, link design scheme and cost. Regarding accuracy and real world applicability, the GPS-based system is superior and accurate. In terms of the operational cost during the first 10 years, however, the cost of RFID-based system was identified lower than that of GPS-based system. The applicability of RFID-based system, in spite of the weakness of accuracy and applicability, was tested successfully in urban settings. Some limitations and future research agenda have also been presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.575-576
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• 2016

Recently utilizing GPS (Global Positioning System) technology has become the research in progress to improve the accuracy. However, if you encounter problems when you receive a satellite signal reception accuracy it is also significantly lowered. In this paper, we designed a system that combines the GPS technology and the GIS (Geographic Information System) technology, which provides information about the specified location to increase the accuracy. Compare the specified location and the user's location information to determine whether the user enters for the location. Accordingly, is utilized by the GIS technique considered to make improve the accuracy of the location information even when there is interference in the received satellite signal, the user receives a service specified location.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.10a
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• pp.63-66
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• 2002