• Journal of the Korean earth science society
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• v.25 no.2
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• pp.109-114
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• 2004

A wavelet method is applied to the analysis of gravity potential. One scaling function is proposed to generate wavelet. The scaling function is shown to be replaced to the Green’s function in gravity potential. The upward continuation can be expressed as a wavelet transform i.e. convolution with the scaling function. The scaling factor indicates the height variation. The multiscale edge detection is carried by connecting the local maxima of the wavelet transform at scales. The multiscale edge represents discontinuity of the geological structure. The multiscale edge method is applied to gravity data from Masan and Changwon.

• Geophysics and Geophysical Exploration
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• v.24 no.1
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• pp.1-5
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• 2021

The closed-form expressions of the vector gravity and gravity gradient tensor due to a circular disk are derived. The gravity potential due to a circular disk with a constant density is defined for a cylindrical system. Then, the vector gravity is derived by differentiating the gravity potential with respect to cylindrical coordinates. The radial component of the vector gravity in the cylindrical system is converted into horizontal gravity components in the Cartesian system. Finally, the gravity gradient tensor due to a circular disk is obtained by differentiating the vector gravity with respect to the Cartesian coordinates.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.5 no.1
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• pp.32-42
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• 1987

Global change and local fluctuation of earth's gravity field play important roles in accurate vertical positioning as well as in accurate horizontal positioning. Regarding the impotance, in this study, the concept of gravity potential theory connected with the influence of gravity field and every kind of height were discussed. Various kind of heights using the observed gravity and leveling data were computed and analysed to study the influence of earth's gravity field in accurate vertical positioning. Taking the route from Busan to Kyongju and investigating the ratios ($\Delta$H/dH) of height defferences (dH) between calculated heights considering gravity field and leveling height to relative heights (dH) between adjacent stations, we get the result that the values by correction formula increase linearly according to latitude, and the values by gravity potential ere strongly influenced by pseudo topography.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.95-106
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• 1994

The purpose of this paper is to establish the optimum reference field as testing some geopotential model, gravity data and GPS data. We have to decide a best fitting geopotential model as a reference surface for establishing the optimum geoid solutions. We conduct some tests on the Korean Peninsula gravity data to establish which of the model would be prove to be the best one. Three ways were used to compare the geopotential coefficient solutions. One of the tests is to compare the residual gravity anomaly remaining after the anomaly computed from the geopotential model has been subtracted from the "observed" gravity anomaly. The second method is a comparison of several geopotential solutions in terms of differences in gravity anomalies and quasi-geoid undulations. The third method is a comparison between the undulation obtained by GPS and the corresponding undulation from each geopotential model. The result showed that OSU91A model is a best fitting model as a reference in the region of Korean Peninsula.Peninsula.

• 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.

• 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.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.4
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• pp.359-367
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• 2000

This paper suggests that coefficients models of the Earth's gravitational potential can be used to calculate height anomalies which are then reduced to the geoid undulation to determine more precise geoid undulation. The potential coefficients and modified coefficients of EGM96 and KODEM33 digital elevation model in and around the Korean peninsula were used for this study. The magnitude of height anomaly computed in this study reached 0.025 m and the mean vaule showed -0.015 m. In this study, geometrical geoid undulation was derived from GPS/Leveling data for evaluating the precisely computed geoid undulation. In comparison with geometric and gravimetric geoid undulations, mean value and standard deviation of the differences showed 0.0114 m and 0.2817 m respectively and it showed the improvement of results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.1
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• pp.131-139
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• 1997

Geopotential models were used to determine the reference surface in geoid modelling and until now, OSU91A model has been most widely used in the world. But what so called EGM96, GSFC/DMA geopotential model published in the latter half of the 1996 by GSFC/DMA project. In this paper, we intended to compare the results of spherical harmonic analyses using the both geopotential model and the spherical harmonic analyses performed up to degree and order 300 and the gravimetric geoidal heights considering gravity data on each $3'\times{3'}$ grid point in and around Korean peninsula. The results showed that the average geoidal height of study area computed from EGM96 is larger 0.40 m than that computed from OSU91A and the gravimetric geoidal heights us-ing EGM96 is larger 0.35 m than that using OSU91A model.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.522-528
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• 1997

Gravity surveys with accompanying spirit levelings were carried out in Mt. Hangye area. From these survey results, orthometric height correctioins were calculated. The correction reaches 5 cm when the height difference is 900 m in this area. The corrections were also calculated using an available Bouguer anomaly map, and they are little different from the previous results. In conclusion, orthometric height corrections are necessary in precise spirit leveling, specially in higher lands, and they can be easily calculated from an available Bouguer anomaly map without laborious gravity surveys.

• Geophysics and Geophysical Exploration
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• v.26 no.1
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• pp.1-7
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• 2023

This study derives the expressions of vector gravity and gravity gradient tensor due to an elliptical cylinder. The vector gravity for an arbitrary three-dimensional (3D) body is obtained by differentiating the gravitational potential, including the triple integral, according to the shape of the body in each axis direction. The vector gravity of the 3D body with axial symmetry is integrated along the axial direction and reduced to a double integral. The complex Green's theorem using complex conjugates subsequently converts the double integral into a one-dimensional (1D) closed-line integral. Finally, the vector gravity due to the elliptical cylinder is derived using 1D numerical integration by parameterizing a boundary of the elliptical cross-section as a closed line. Similarly, the gravity gradient tensor due to the elliptical cylinder is second-order differentiated from the gravitational potential, including the triple integral, and integrated along the vertical axis direction reducing it to a double integral. Consequently, all the components of the gravity gradient tensor due to an elliptical cylinder are derived using complex Green's theorem as used in the case of vector gravity.