• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.2
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• pp.121-134
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• 2013

The transverse cylindrical projection has been used in Korea since 1910s when the nationwide geodetic network was firstly established. However, the projection has a number of different types of functions according to a way of its mathematical derivation as well as a section of its coefficients and terms, for instance Gauss- Schreiber(GS) and Gauss-Kruger(GK) types. Although the transverse cylindrical projection itself is assigned to a system, projected coordinates would be diverse with respect to the function used in the actual calculation. In order to investigate impact of functions used in the computation, five different equations (i.e., 2 GS and 3 GK) were implemented in this study by using MATLAB. A series of numerical simulation tests has been carried out to compare and characterize them in terms of projection accuracy, difference of projected coordinates and distortion. Furthermore, a comparison between GS and GK function was made under the Korean gridding system, consisting of four zones. Results from the numerical computations were qualitatively analyzed and summarized in this paper.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.5
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• pp.343-353
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• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.101-107
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• 1985

The coordinates of triangulation stations which has been used in Korea, were computed by means of the Gauss Conformal Double Projection in the 1910's. This projection has been considered as a problem in respect of accuracy, because the farther a station is from the origin, the larger the computational error becomes. In this paper, the Gauss Conformal Double Projection is compared with the T.M(Transverse Metcator) Projection which is widely used in many countries. In T.M projection method more accurate ground coordinates are obtained. This paper has an objective to improve the accuracy of public surveying by using the method presented in this paper.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.6
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• pp.485-495
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• 2015

The Tohoku Earthquake, which hit Japan on March 11, 2011, was a massive magnitude 9.0 earthquake, with the earthquake itself causing damage and the resulting tsunami additionally causing enormous material and human damage. The crustal deformation at that time reached a maximum of 5.24 m in Japan, Neighboring countries South Korea and China as well as the Southeast Asian region also witnessed crustal deformation ranging from a few centimeters to a few meters. The detailed analysis in this study based on data from 72 of the sites in South Korea where GNSS CORS was installed showed that South Korea underwent heterogeneous crustal deformation from the Tohoku earthquake, with a maximum of 55.5 mm, a minimum of 9.2 mm, and an average of 22.42 mm. A crustal deformation model was developed, applied, and evaluated for accuracy in this study for a prompt revision of the survey results of the control points that were changed by the crustal deformation. The survey results were revised by applying a crustal deformation model to the 1,195 unified control points installed in South Korea prior to the Tohoku earthquake. The comparison of these 1,195 points with their new survey results showed that the RMSE decreased from 14.1 to 3.4 mm and that the maximum result difference declined from 39 to 10 mm. Revision of the survey results of the control points using the crustal deformation model is deemed very useful considering that the accuracy of the survey results of the unified control points in South Korea is 3 cm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.3
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• pp.299-308
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• 2016

Various space geodetic techniques have been developed for highly precise and cost-efficient positioning solutions. By correcting the physical phenomena near the earth’s surface, the positioning accuracy can be further improved. In this study, the vertical crustal deformation induced by the ocean tide loading was accurately estimated through GNSS absolute and relative positioning, respectively, and the tidal constituents of the results were then analyzed. In order to validate the processing accuracy, we calculated the amplitude of eight major tidal constituents from the results and compared them to the global ocean tide loading model FES2004. The experimental results showed that absolute positioning and positioning done every hour during the observation time of 2 hours, which yielded an outcome similar to the reference ocean tide loading model, were better approaches for extracting tide constituents than relative positioning. As a future study, a long-term GNSS data processing will be required in order to conduct more comprehensive analysis including an extended tidal component analysis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.4
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• pp.405-414
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• 2001

Plate tectonics is a dominant paradigm in modern geophysics. Because of its geological mechanism, Korea has a possibility of earthquake according to plate motion. Besides the disaster of earthquake grows rapidly, the importance of recognition for earthquake has been emphasized. This study attempts to decide crustal movement parameters with GPS data, analysed baseline after processing data with GIPSY-OASIS II S/W, observed from 6 stations in and around the Korean peninsula, and obtained from selected 11 stations in Korea. As a results, maximum shear strain was $0.04{\mu}/yr$ and the mean azimuth of the maximum compression axes$(A_{z2})$ is estimated as $97.75^{\circ}$ in and around the Korean peninsula. The average rate of the maximum shear strain($({\gamma}_max)$) is $0.17{\mu}/yr$. The mean azimuth of the maximum compression axes$(A_{z2})$ is estimated as $70.25^{\circ}$ in Korea. Such a pattern of strain distribution is harmonious with that of seismic activity in Korea both historically as well as today.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.2
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• pp.153-162
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• 1995

The coordinate transformation both WGS84 and Bessel ellipsoids is essential to use of GPS in South Korea. Especially, for transformation considered the needed accuracy and the regional characteristics, the study about geoid modeling and the characteristics on the transformed area should be done. The aim of this study define the characteristics of the transformed coordinates according to transformation methods and the area measured by GPS. For this, large network that include South Korea, four regional network consist of large network, and local net-work include Incheon city designed. Geoid model based on Bessel suitable to South Korea selected from study about the effects of the assumed geoid height at the geodetic origin, and then coefficients computed according as transformed area and methods. Also, the transformed characteristics of the large coefficients, the regional coefficients, and the local coefficients according to methods compared, analyzed synthetically.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.4
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• pp.415-423
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• 2001

This paper deals with the data processing method relative to reference frames through the calculation of absolute coordinates of permanent GPS site which was established at Sungkyunkwan University. In this paper. we computed the ITRF97 coordinates with high precision (0.0001 ppm) from GPS data analysis. Also, we derived the accurate coordinates referred to WGS84 and Korean Geodetic Datum (KGD) using transformation parameters provided. ITRF97 coordinates were computed by using the GIPSY-OASIS II (GOA II) software and the algorithms for determining the position developed Jet Propulsion Laboratory (JPL). The coordinates referred to WGS84 and KGD were derived from the transformation parameters provided by International Earth Rotation Service (IERS) and National Geography Institute (NGI). The parameters determined by NGI were calculated from the 2000 project of the establishment of geocentric coordinate system. We tested its availability through the comparison of the coordinates obtained from local GPS data analysis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.2
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• pp.163-172
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• 1994

As for the baseline measurement using geodetic GPS receiver, this paper puts forth the effective measurement range of a low-priced GPS system receiving Ll frequency only. Compared with the data of baseline eliminated the ionospheric effects with L1/L2 frequencies, the results with Ll frequency approximate to those with dual frequency within the range of 15 km (the baseline discrepancy of the two methods is less than 2 cm). The results with Ll frequency are better within the range of 18 km. Based upon the analysis of data, we find that the convergence limit of integer ambiguity-applicable to double difference fixed solution- is about 18 km and the ionospheric effects have a great influence on the results when the baseline are longer than 20 km. This study also presents a standard which makes it possible to select the favorable data from the results of the GPS relative distance measurements.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.3
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• pp.303-310
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• 2009

We processed seven years data of 142 IGS(International GNSS Service) stations were processed, which have been selected with an optimal network algorithm, to realize terrestrial reference system. To verify the result, a comparison with the ITRF2005 was given both in positions and velocities with transformation parameters estimation. The transformation parameters are within 4.3 mm in length, while the RMS(root mean square) difference of positions and velocities are 6.7 mm and 1.3 mm/yr in horizontal and 13.3 mm and 2.4 mm/yr in vertical, respectively, which represent good coincidences with ITRF2005. This research would help developing our own geodetic reference frame and may be applied for the global earth observations such as the global tectonics. A further improved TRF would be expected by applying various data processing strategies and with extension of data in number and observation period.