• Journal of the Korean Geophysical Society
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• v.9 no.3
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• pp.209-217
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• 2006

The major continental blocks in NE-Asia are the North China Block and the South China Blo, which have collided, starting from the Korean peninsula. The suture zone in NE China between two blocks is well defined from the QinIing-Dabie-Orogenic Belt to the Jiaodong (Sulu) Belt by the geological and geophysical interpretation. The discovery of high pressure metamorphic rocks in the Hongsung area of the Korean peninsula can be used to estimate the suture zone. This indicates that the suture zone in the Jiaodong Belt might be extended to Hongsung area. However, due to the lack of geological and geophysical data over the Yellow sea, the extension of the suture zone to the Korean peninsula across the Yellow Sea is obscure. To find out the tectonic relationship between NE China and the Korean peninsula it is necessary to complete U-ie homogeneous geophysical dataset of NE Asia, which can be provided by satellite observations. The CHAMP lithospheric magnetic field (MF3) and CHAMP-GRACE gravity field, combined with surface measured data, allow a much more accurate in-ference of tectonic structures than previously available. The CHAMP magnetic anomaly map reveals significant magnetic lows in the Yellow Sea near Nanjing and Hongsung, where are characterized by gravity highs on U-ie CHAMP-GRACE gravity anomaly map. To evaluate the depth and location of poten-tial field anomaly causative bodies, the Euler Deconvolution method is implemented. After comparing the two potential field solutions with the simplified geological map containing tectonic lines and the distribution of earthquakes epicenters, it is found that the derived structure boundaries of both are well coincident with the seismic activities as well as with the tectonic lineaments. The interpretation of the CHAMP satellite magnetic and GRACE satellite gravity datasets reveal two tectonic boundaries in U-ie Yellow Sea and the Korean peninsula, indicating U-ie norttiern and southern margins of the suture zone between the North China Block and the South China Block. The former is extended from the Jiaodong Belt in East China to the Imjingang Belt on the Korean peninsula, the later from Nanjing, East China, to Hongsung, the Korean peninsula. The tectonic movement in or near the suture zone might be responsible for the seismic activities in the western region of the Korean Peninsula and the development of the Yellow Sea sedimentary basin.

• Journal of the Korean Geophysical Society
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• v.8 no.2
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• pp.89-92
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• 2005

For the understanding the locus of the Quinling-Dabie-Sulu continental collision’s boundary and the underground structure of the sedimentray basin in the Yellow Sea, three dimensional density modelling is carrid out by using gravity dataset (Free Air Anomaly), which is measured by Tamhae 2, GIGAM in a period 2000-2002. The measured gravity anomaly in the investigations area is mainly responsed by depth distribution of the sedimentary basin. After comparing the sea-measured gravity data to CHAMP-GRACE satellite gravity data, I suggested that the high density model bodies extend mainly from the southern part of China to the middle-western part of the Korean Peninsula, which might be emplaced along the continental collision’s boundary. The total volume of very low density bodies modified by modelling might be about 20 000 km3.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.9-14
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• 2005

For the understanding the locus of the Quinling-Dabie-Sulu continental collision's boundary and the underground structure of the sedimentray basin in the Yellow Sea, three dimensional density modelling is carrid out by using gravity dataset (Free Air Anomaly), which is measured by Tamhae 2, KIGAM in a period 2000 - 2002. The measured gravity anomaly in the investigations area is mainly responsed by depth distribution of the sedimentary basin. After comparing the sea-measured gravity data to CHAMP-GRACE satellite gravity data, I suggested that the high density model bodies extend mainly from the southern part of China to the middle-western part of the Korean Peninsula., which might be emplaced along the continental collision's boundary. The total volume of very low density bodies modified by modelling might be about $20000\;km^3$.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.589-592
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• 2005

Gravity characteristics and Moho undulations are investigated in the Korean peninsula by using satellite gravity data. According to the development of satellite geodesy, gravity potential models which have high accuracy and resolution were released. Using the EIGEN-CGOIC model based on low orbit satellite data such as CHAMP and GRACE, geoid and gravity anomaly were calculated by spherical harmonic analysis. The study area is located at $123^{\circ}\sim132^{\circ}E, 33^{\circ}\sim43^{\circ}$N including Korea. Free-air anomalies, which show the effect of terrain, have the values between $-37\sim724 mgal. After Bouguer correction, the range of simple Bouguer anomalies is $-221\sim246$ mgal. Complete Bouguer anomalies after terrain correction increase from continent to marine. This phenomenon is related rise of Moho discontinuity. The cut-frequency for extraction of Moho undulation was determined by power spectrum analysis, and then 3D inversion modeling was implemented. The mean, maximum, minimum, and standard deviation of Moho depth undulation are -26, -36, -8, and 4.9 krn, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.261-266
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• 2005

According to development of satellite geodesy, gravity potential models which have high accuracy and resolution were released. Using the EIGEN-CG01C model based on low orbit satellite data such as CHAMP and GRACE and the EGM96 model, geoid and gravity anomaly were calculated and compared. The study area is located at $123^{\circ}{\sim}132^{\circ}$ E, $33^{\circ}{\sim}43^{\circ}$ including Korea. Comparing two models, very high correlation more than 0.90 in geoid and gravity anomaly was observed, but in amplitude analysis the EIGEN-CG01C model have higher amplitude in high frequency area. Gravity anomaly calculated with both models shows a little difference in North Korea and some coast area of the Yellow sea. Through power spectrum analysis, residual anomaly that can be used in large scale structure or underground resources survey was calculated.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.99-104
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• 2006

The new gravity field combination models are expected to improve the knowledge of the Earth's global gravity field. This study evaluates eleven global gravity field models derived from gravimetry and altimetry surface data in a comparison with ground truth in South Korea. Geoid heights obtained from GPS and levelling in South Korea are compared with geoid heights from the models. The results show that the gravity satellites CHAMP, GRACE and LAGEOS plus gravimetry and altimetry surface data have led to an improvement in gravity field models. As expected, the new combination gravity field model which are EIGEN-CG03C and EIGEN-GL04C give better results than the predecessors widely used models(EGM96, OSU91A etc.).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.353-358
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• 2005

The purpose of this paper is to evaluate a new geopotential model, EIGEN-CG01C which had been developed from CHAMP and GRACE mission observations and surface gravity data. The accuracy analysis was conducted by comparing the geoidal heights computed from two types of geopotential models (i.e., EIGEN-CG01C and EGM96) with spirit leveled GPS bench mark. To this end, three hundred twenty GPS leveled bench marks are used as bases for the numerical investigation. From the analysis, it was possible to conclude that EIGEN-CG01C was more suitable to upgrade the KGEOID 98 since the results that the EGM96 was slightly biased.

• The Journal of the Petrological Society of Korea
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• v.22 no.1
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• pp.35-47
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• 2013

The Baegdusan Volcano which erupted violently at 1000 AD is still have possibility of eruption. Therefore, it is necessary to monitor regularly the possibility of eruption. However, it is very difficult to install regular monitoring system or to get regularly monitored data due to geopolitic problems. This is why we have to develop regular monitoring technique using satellite. The geoid in the Baegdusan Volcanic area calculated from gravity data obtained from GRACE satellite, decreased from 2002 to 2005. The period of decreasing is well matched with time when magma activities were recognized in the Baegdusan Volcanic area. The decrease in geoid is interpreted to be caused by the decrease of water storage. Considering that the amount of rainfall from 2002 and 2005 is almost constant, the decrease in geoid may be related to the magma activity under the Baegdusan Volcano. The geomagnetic total force in the Baegdusan Volcanic area measured by CHAMP satellite, decreased from 2000 to 2005 and increased after 2005. The period of decrease is well matched with the time with increased activity of magma chamber under the Baegdusan Volcano indicating that the decrease of geomagnetic total force is caused by demagnetization of surrounding rocks due to the increase of temperature of magma chamber. These data indicate the possbility of using change of geoid and geomagnetic total force observed by GRACE and CHAMP satellites for the monitoring of magma activity under the Baegdusan Volcano.