• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.141-149
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• 1993

The gravimetric geoid of the South Korea Region was computed on Geodetic Reference System 1980(GRS80) using a combination of satellite-derived potential coefficients and terrestrial gravaty data. $10^{\prime}{\times}10^{\prime}$ mean gravity anomalies were obtained from surface gravity data for the outer zones, $1^{\circ}{\times}1^{\circ}$ equal area mean anomalies were used for the inner zones, and point gravity anomalies were used for the innermost zones in the Stokes integration. The GRS80 potential coefficients were obtained from modification of GEM9 data and Integration was extended over a spherical cap of $30^{\circ}$ from the integration area. The results of a free-air geoid show that the systematic mean difference of approximately 2~3m in comparison of OSU89B model.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.167-172
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• 1990

A number of studies for the improvement of the accuracy of the Loran C fix were carried out previously. But most studies were preformed when a ship was at anchorage, or in port. To investigate the accuracy of the Loran C fix when a ship was underway and in port, a series of observation was made on the route between Pusan and Cheju from Oct. 1988 to Oct. 1989. The obtained results are summerized as follows: 1. There is little difference in the accuracy of the Loran C fix by daytime and night, and the higher the mountain nearby ship, the greater the error of ship's position. 2. When a ship is at anchorage and underway, and the accuracy of ship's position is almost not affected by course while underway. 3. In order to promote the accuracy of the fixed position, a navigator must correct the propagation velocity and the geodetic system simultaneously, but in this paper the authors find that a most accurate position can be obtained by converting the geodetic system only.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1209-1217
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• 1994

This paper proposed transformation coefficients suitable to South Korea for the establishment of coordinate transformation system between Bessel and WGS84 ellipsoids. For this, the coordinates transformation algorithms concerned with parameter methods was developed, and global test network which has 15 astronomical points in South Korea were designed. Based on signals received from GPS, computed the geoid undulation by GPS/Leveling, and derived parameters(3-, 4-, 6-, and 7-parameter) for transformation between each ellipsoid, applied global networks to study the characteristics of transformation according to parameters. Through the successful application of 7-parameters derived in this study and 7-parameters proposed by DMA for map projection, transformation coefficients suitable to South Korea was proposed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.4
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• pp.317-325
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• 2001

Although GPS has proven to be efficient in the fields of navigation and surveying, it has many problems of positioning in downtown areas. Therefore, if GPS is combined with GLONASS which is similar to GPS in its positioning and signal system, it is expected that accuracy will be improved. However, we should address certain problems that exist related to the coordinate, time, and signal system between the two. The purpose of this study is to develop a GPS/GLONASS combination program by considering the properties of GPS and GLONASS and to solve the problems related to differences in the coordinates system and signal system. It is also to present the efficiency of the program in navigation and geographic information through analyzing 3D positioning accuracy by GPS/GLONASS combination with an application experiment. As a result of this study, the accuracy of the DGPS/DGLONASS positioning program corresponded to that of commercial program, and that's accuracy was better than that of DGPS. Especially, the acquisition of navigation and geographic information was possible by DGPS/DGLONASS combination in downtown area where the continuous 3D positioning is impossible by DGPS only.

• Korean Journal of Community Nutrition
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• v.1 no.3
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• pp.405-422
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• 1996

The purpose of this study is provide reference data for anthropometry and body composition and also to compare body fat estimation among skinfold thickness, BIA and NIR methods. Anthropometric measurements of height, weight, eight sites of skinfolds and six sites of circumferences were taken from 76 elderly male and 153 elderly female. Skinfold thicknesses, body composition and circumferences except waist were lowered with advancing age in elderly females and males. The degree of change with age vaired among parameters but was consistently and significantly(p<0.05) greater in elderly females than I males. Although sum of skinfold thicknesses and the amount of central and peripheral fat were significantly higher in females than that of males, the ratio of central fat to peripheral fat was significantly greater in males than in females. WHR is also significantly higher in males than that of females. This indicates that fat distribution of males tend to be centralized toward the trunk of the body than females. Estimation of body fat from skinfold thickness(male : 18.5$\pm$4.1$\%$, female : 29.7$\pm$4.0$\%$) and BIA(male : 19.5$\pm$7.3$\%$, female : 29.6$\pm$6.7$\%$) were similar but were significantly different from NIR method(male : 24.7$\pm$5.6$\%$, 34.8$\pm$4.9$\%$). Estimation of body fat by NIR measurement seemed to be more overestimated. Understanding the normal changes in body composition with increasing old age, and the ability to measure these changes and compare them with appropriate reference data are important for the health of the elderly.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.105-113
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• 2009

Heat energy exchange is very important processes in the coastal wetland ecosystems. We observed and analyzed the net radiation flux, the sensible heat flux, the latent heat flux and the soil heat flux, which are balanced in the heat energy balance, over a reclaimed land covered with reeds at Goheung, Jeonllanamdo where is horizontally plane. The atmospheric turbulence had been measured in order to estimate the heat transfer during 5 intensive observation periods (IOPs). It was considered that the soil consists of water, fine particles, and vegetation canopy that changes color and density according to the season. We examined the characteristics of the heat flux and the vegetation effect on the air temperature control. It was noted that the heat was transported mainly by latent heat flux in the summer season and the vegetation canopy decreased the daily temperature range due to the heat storage. The air temperature was lower at the IOPs site than near urban area. This showed that the coastal wetland covered with the vegetation control the thermal environment.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.691-697
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• 2005

Recently, the development of accurate gravity-meter and GPS make it possible to obtain high resolution gravity data. Though gravity data interpretation like modeling and inversion has significantly improved, gravity data processing itself has improved very little. Conventional gravity data processing removes gravity effects due to mass and height difference between base and measurement level. But, it would be a biased density model when some or whole part of anomalous bodies exist above the base level. We attempted to make a multiquadric surface of the survey area from topography with DEM (Digital Elevation Map) data. Then we constituted rectangular blocks which reflect real topography of the survey area by the multiquadric surface. Thus, we were able to carry out 3-D inversions which include information of topography. We named this technique, 3-D Gravity Terrain Inversion (3DGTI). The model test showed that the inversion model from 3DGTI made better results than conventional methods. Furthermore, the 3-dimensional model from the 3DGTI method could maintain topography and as a result, it showed more realistic geologic model. This method was also applied on real field data in Masan-Changwon area. Granitic intrusion is an important geologic characteristic in this area. This method showed more critical geological boundaries than other conventional methods. Therefore, we concluded that in the case of various rocks and rugged terrain, this new method will make better model than convention ones.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.1
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• pp.18-24
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• 1987

For the purpose of getting the accuracy of NNSS fix, the continuous observation was performed to search the factors affecting the accuracy of NNSS fix, and then to examine their effects. The observation was made at Lat. $35^{\circ}'||'&'||'<\TEX>05'04"N, Long. '||'&'||'129^{\circ}'||'&'||'<\TEX> 02'13"E from 28th January to 20th July in 1985. Accuracy of the position fixed in accordance with the observation time, each satellite, elevation angle doppler count, passed direction of each satellite and the antenna height were analyzed. The results obtaines are summerized as follows: 1. The deflaetion error is reduced to 0.21 miles when the geodetic system of the calculating the position converted from WGS-72 to Bessel. 2. When the elevation angle of the mountain is high, or the range of the elevation angle of satellite is 20-70 degrees, the position fixed comes nearest the true position. 3. The position fixed is more accurate on the condition that doppler count is more than 21, and at night than in daytime. 4. The accuracy of the position fixed is more seriously affected when the input data of the antenna height has considerable errors. But there occures almost little difference in the accuracy of position according to each satellite.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.4
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• pp.127-138
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• 2011

This study aimed at suggesting the possibility of an application that connects cadastral control point and urban control point. In order to do this, we calculated and analyzed the cadastral coordinate on urban control point by using the GPS observation data of Changwon-si urban control point (32 points) which was announced based on the result of global coordinate system. We calculated cadastral coordinate through using three different kinds of calculation S/Ws, and compared the results of the calculation with the preexisting result of urban control point. The comparison suggested that the gap between the new results and the existing results is in the range of error specified by a law. Therefore, the result can be used in cadastral surveying. However, for the safe application in practical works, we suggested that it would be better to carry out new cadastral surveying and use its result than to use the result of the current urban control point directly in surveying cadastral. In addition, we suggested that it is necessary to examine precisely the local station of triangulation. Finally, we recommended that one should use trilateral network adjustment S/W as one's calculation S/W.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.139-151
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• 2018

The National Base Map construction consists of the regular correction work of dividing the whole country into two regions and carrying out the modification Plotting by aerial photographs every two years as well as the real time updating work of correcting the major change feature within two weeks by the field survey and the As-Built Drawing. In the case of the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS) used for real time updating work of the National base map, the coordinate transformation error is included in the positional error when applied to the National Base Map based on the World Geodetic Reference System as the coordinate system based on the Regional Geodetic Reference System. In addition, National Base Map is registered based on the outline(eaves line) of the building in the Digital Topographic Map, and the Cadastral and Architecture are registered based on the building center line. Therefore, the Building Object management standard is inconsistent. In order to investigate the improvement method, the network RTK survey was conducted directly on a location of the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS) and the problems were analyzed by comparing with the plane plotting position reference in National Base Map. In the case of the general structure with the difference on the Building center line and the eaves line, beside the location information was different also the difference in the ratio of the building object was different between Building center line and the eave. In conclusion, it is necessary to provide the Base data of the double layer of the Building center line and the outline of the building(eaves line) in order to utilize the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS). In addition, it is necessary to study an organic map update process that can acquire the up-to-dateness and the accuracy at the same time.