• Spatial Information Research
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• v.18 no.4
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• pp.33-41
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• 2010

Approximately 100 permanent GPS stations are currently operational in Korea. However, only 10 sites have their own weather sensors connected directly to the GPS receiver. Thus. calculation of meteorological data through interpolation of AWS data are needed to determine precipitable water vapors at a specific GPS station without a meteorological sensor. This study analyzed the accuracy of two meteorological data interpolation methods called reverse sea level correction and kriging. As a result, the root-mean square-error of reverse sea level correction were seven times more accurate in pressure and twice more accurate in temperature than the kriging method. For the analysis of PWV accuracy, we calculated GPS PWV during the summer season in :2008 by using GPS observation data and interpolated meteorological data by reverse sea level correction. And, we compared GPS PWV s based on interpolated meteorological data with those from radiosonde observations and GPS PWV s based on onsite GPS meteorological sensor measurements. As a result, the accuracy of GPS PWV s from our interpolated meteorological data was within the required operational accuracy of 3mm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.305-316
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• 2015

The GPS signal delays in troposphere, which are along the signal path between a transmitting satellite and GPS permanent station, can be used to retrieve the precipitable water vapor. The GPS remote sensing technique of atmospheric water vapor is capable of monitoring typhoon and detecting long term water vapor for tracking of earth’s climate change. In this study, we analyzed GPS precipitable water vapor variations during the heavy snowstorm event occurred in the Yeongdong area, 2014. The results show that the snowfall event were occurring after the GPS precipitable water vapor were increased, the maximum fresh snow depth was recorded after the maximum GPS precipitable water vapor was generated, in Kangneug and Wuljin, respectively. Also, we analyzed that the closely correlation among the GPS precipitable water vapor, the K-index and total index which was acquired by the upper air observation system during this snowstorm event was revealed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.1
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• pp.9-17
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• 2003

Typhoon RUSA, which caused serious damage was passed over in Korea peninsula during 30 August to 1 September, 2002. We estimated tropospheric wet delay using GPS data and meteorological data during this period. Integrated Water Vapor(IWV) gives the total amount of water vapor from tropospheric wet delay and Precipitable Water Vapor(PWV) is calculated the IWV scaled by the density of water. We obtained GPS PWV at 13th GPS permanent stations(Seoul, Wonju. Seosan, Sangju, Junju, Cheongju, Taegu, Wuljin, Jinju, Daejeon, Mokpo, Sokcho, Jeju). We retrieve GPS data hourly and use Gipsy-Oasis II software and we compare PWV and precipitation. GPS observed PWV time series demonstrate that PWV is, in general, high before and during the occurrence of the typhoon RUSA, and low after the typhoon RUSA. GPS PWV peak time at each station is related to the progress of a typhoon RUSA. We got very near result as we compare GMS Satellite image with tomograph using GPS PWV and we could present practical use possibility by numerical model for weather forecast.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.547-554
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• 2009

The Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite, which is one of the Earth Observing System satellites managed by National Aeronautics and Space Administration, provides global measurements of the water vapor in the atmosphere using infrared (IR) channels. In this paper, we restored precipitable water vapor (PWV) over a permanent GPS station in Incheon using the IR measurements of AIRS and compared the result with GPS-based PWV estimates. As a result, AIRS PWV had similar trends with GPS PWV; the bias of AIRS PWV against GPS PWV is 0.3 cm and root mean square error (RMSE) 0.7 cm. In addition, the correlation coefficient between AIRS PWV and GPS PWV was 0.89. Thus we conclude that the AIRS PWV reflects local characteristics of the water vapor content.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.54-62
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• 2004

According to the Korea Tectonic Map, the Korean Peninsula can be divided into seven tectonic units and each of them shows a peculiar deformation pattern. In order to estimate an amount of crustal deformation in the Korean peninsula, we obtained the velocity vector fields of South Korea by dealing with the data set of the years 2001 and 2002, measured from the permanent GPS stations across the country To obtain a relatively precise coordinate of each station, we used GAMIT that is a comprehensive GPS analysis package developed at MIT, Then, a Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative velocity vector for the crustal deformations. The crustal movement of South Korea is turned out to be about 1mm per year westward and about 0.6mm per year southward. In case of Suwon and Seosan(Gyeonggi Massif), the movement occurs slightly to the north-east direction. The movement of a relative velocity field in the tectonic unit is unidirectional, yet the magnitude of the velocity is very small.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.645-653
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• 2010

In this study, IGS(International GNSS Service) stations were processed by the method of PPP(Precise Point Positioning), and velocities of crustal movements about the region of the Korean Peninsula were calculated precisely. The characteristics of crustal movements around Korean Peninsula were understood by velocity calculation of crustal movements. We confirmed from the result which calculated by crustal movement velocity shows the movement Eurasia and North America plate move to south-east, and Philippine plate moves to north-west. This result is respected to be utilized as a basic data about analysis of earthquake and earth physics.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.545-554
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• 2013

Augustine is an active stratovolcano located in southwest of Cook Inlet, about 290 kilometers southwest of Anchorage, Alaska. Between January 11 and 28, 2006, the volcano erupted explosively 14 times. We collected twelve permanent GPS stations operating by Plate Boundary Observatory (PBO) from 2005 to 2011. All data processing was carried out using Bernese GPS Software V5.0 with IGS precise orbit. Static baseline processing by fixing AC59 station was applied for the volcano activity monitoring. AC59 is the nearest (about 24.5 km) station to Augustine volcano, and located on North America Plate including Augustine Island. The test results show inflation (9.7 cm/yr) and deflation (-9.2 cm/yr) of volcano before and after eruption around crater clearly. After volcano activity has reached a plateau, some of the GPS stations installed north of the volcano show ground subsidence phenomenon caused by compaction of pyroclastic flows. These results indicate the possibility of using surface deformation observed by GPS for monitoring and prediction of volcano activity.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.21-28
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• 2010

The classical RTK System requires that GPS data is transmitted from a single reference receiver to one or more roving units. But its error increase due to distance between reference and rover. VRS(Virtual Reference Station) system, a network of reference stations can be used to isolate the components of these systematic errors and use the resultant corrections to create Virtual Reference Stations at any location within the network. Use of a VRS significantly reduces the effects of systematic errors and improved accuracy. In this study, Network-RTK survey using VRS serviced by NGII(National Geographic Information Institute) was performed and the results were compared with results of total station surveying and notified coordinates of cadastral control points for utilization assessment of VRS.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.825-832
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• 2012

GPS signal delay that caused by dry gases and water vapor in troposphere is a main error source of GPS point positioning and it must be eliminated for precise point positioning. In this paper, we implemented to generate tropospheric delay grid map over the Korean Peninsula based on post-processing method by using the GPS permanent station network in order to determine the availability of tropospheric delay generation algorithm. GIPSY 5.0 was used for GPS data process and nationwide AWS observation network was used to calculate the amount of dry delay and wet delay separately. As the result of grid map's accuracy analysis, the RMSE between grid map data and GPS site data was 0.7mm in ZHD, 7.6mm in ZWD and 8.5mm in ZTD. After grid map accuracy analysis, we applied the calculated tropospheric delay grid map to single frequency relative positioning algorithm and analyzed the positioning accuracy enhancement. As the result, positioning accuracy was improved up to 36% in case of relative positioning of Suwon(SUWN) and Mokpo(MKPO), that the baseline distance is about 297km.