• Title, Summary, Keyword: 중력포텐셜모형

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Demand Characteristics and Analysis of Changes in Spatial Accessibility of Public Sports Facilities (공공체육시설 수요특성 및 공간적 접근성 분석)

  • Kim, Seong-Hee;Kim, Yong-Jin
    • The Journal of the Korea Contents Association
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    • v.17 no.7
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    • pp.283-293
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    • 2017
  • This study analyzed the actual conditions of use of public sports facilities and characteristics of the users of the facilities through surveys and measured the spatial imbalance of the public sports facilities currently supplied by using gravity potential model. This study also suggests evaluation criteria that may be considered for efficient location selection by examining the change of accessibility to the facilities that meet the needs of users in the future. As the results of the questionnaire survey, unlike current usage, the users hoped for badminton, weight training and swimming. And we could confirm the demand for the expansion of the multi - purpose indoor gym which can carry out such activities in the areas. As the result of the analysis on the difference in accessibility of the public sports facility, there were some large variations in the regions. It was found that a balanced supply of facilities was needed in terms of equity. In particular, when analyzing by considering the population estimates of 2025, It is analyzed that the accessibility will be reduced to about 60% compared to that of 2015. In addition, it is evaluated as the best alternative in terms of overall efficiency that the location of the facilities should be in Munsan area where population growth is expected in the future.

Application of Relative Gravity Surveying and Modeling to Sinkhole Detection (싱크홀 탐지를 위한 상대중력측량과 중력모델링 기법의 활용)

  • Kim, Jinsoo;Lee, Young-Cheol;Lee, Jung-Mo
    • Korean Journal of Remote Sensing
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    • v.33 no.3
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    • pp.267-274
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    • 2017
  • The purpose of this research was to develop and present methods to detect sinkholes which can exist underneath the surface of the ground. First, we buried a water tank with dimensions $1.8{\times}0.8{\times}0.8m$ at a distance of 1.8 m from the surface. This played the role of the sinkhole. Secondly, we created a square zone with sides 12 meters away from the buried water tank. Within this zone, we measured the gravity at 1-meter intervals using a Scintrex CG5 relative gravimeter with a resolution of 0.001 mGal. Additionally, we performed three-dimensional (3-D) gravity modeling to calculate the theoretical values of the relative gravity around our model sinkhole. The resulting values for the relative gravity around the sinkhole depended on the method used. The measured effect of gravity was 0.036 mGal and the effect calculated using 3-D modeling was 0.024 mGal. Our results suggest that sinkholes that are similar in size to the water tank used in this study can be detected using relative gravity surveys. Smaller sinkholes can be detected by reducing the intervals between the relative gravity measurements.

PRECISE ORBIT PROPAGATION OF GEOSTATIONARY SATELLITE USING COWELL'S METHOD (코웰방법을 이용한 정지위성의 정밀궤도예측)

  • 윤재철;최규홍;김은규
    • Journal of Astronomy and Space Sciences
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    • v.14 no.1
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    • pp.136-141
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    • 1997
  • To calculate the position and velocity of the artificial satellite precisely, one has to build a mathematical model concerning the perturbations by understanding and analysing the space environment correctly and then quantifying. Due to these space environment model, the total acceleration of the artificial satellite can be expressed as the 2nd order differential equation and we build an orbit propagation algorithm by integrating twice this equation by using the Cowell's method which gives the position and velocity of the artificial satellite at any given time. Perturbations important for the orbits of geostationary spacecraft are the Earth's gravitational potential, the gravitational influences of the sun and moon, and the solar radiation pressure. For precise orbit propagation in Cowell' method, 40 x 40 spherical harmonic coefficients can be applied and the JPL DE403 ephemeris files were used to generate the range from earth to sun and moon and 8th order Runge-Kutta single step method with variable step-size control is used to integrate the the orbit propagation equations.

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Comparative Studies of Methods for Continuation and Derivatives of Potential Fields (포텐셜장(場)의 상하향연속(上下向連續) 및 미분법(微分法)에 대(對)한 비교연구(比較硏究))

  • Kwon, Byung Doo
    • Economic and Environmental Geology
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    • v.14 no.2
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    • pp.93-102
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    • 1981
  • Studies of model potential fields continued upward and downward show differences depending on the method of continuation. Beginning with a magnetic field computed over a buried vertical cylinder, the field was continued to various levels by a method introduced by Henderson (Lagrangian interpolation) and by a spectral method (frequency domain analysis). Resultant fields show (1) no significant differences in upward continued values, (2) in downward continuation, accurate values are obtained with the spectral method over the central part of the anomaly, and (3) accurate values are obtained with Henderson's method on the flanks of the anomaly, while oscillations usually characterize the spectral method in this region. Essentially the same observations are made for derivative calculations. Field oscillations are empirically predicted at levels continued to approximately two-thirds of the depth of the source. Our spectral computer program output yields marked oscillations at one-half of the depth of the source. Henderson's method shows no oscillations at this depth and only minor oscillations at the top of the body (some negative values appear on the flanks of the anomaly). The Henderson output is a smooth field even if continued below the top of the body. These results suggest that the presence of oscillations cannot be used to identify the top of a buried source without careful consideration of the method used to continue the field. Use of the derivative to outline and isolate anomalies must similarly include consideration of the method of calculation.

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