• Title, Summary, Keyword: 지구중력장모형

Search Result 5, Processing Time 0.029 seconds

Geoid Heights of Provinces in South KOREA by Earth Gravitational Models (지구중력장모형에 따른 국내 지역별 지오이드고)

  • Lee, Yong-Chang
    • The Journal of the Korea Contents Association
    • /
    • v.8 no.9
    • /
    • pp.274-280
    • /
    • 2008
  • The new high order Earth's gravity Model(EGM2008) are expected to improve the application about the Earth's global gravity field. The objectives of this research are to present characteristics on the geoid heights of provinces in South KOREA which calculated from the height anomalies by Earth Gravity Models. For this, seven EGMs (EGM2008<2,190>, EGM2008<360>, EGM96, EIGEN-GL04C, EIGEN-CG03C, EIGEN-GL04S1, and ITG-Grace02S) selected. Geoid heights of fifty BM check points by GPS/levelling are compared with those by NORI-05 model and seven EGMs. And also, geoid heights of 30"$\times$30" grid points in land(sixes blocks ; $1^{\circ}\times1^{\circ}$ sampled) and sea (four blocks ; $1^{\circ}\times1^{\circ}$ sampled) areas of South KOREA by EGM2008 are compared with those by NORI-05 and six EGMs. The results show that geoid heights obtained from EGM2008(2,190) of NGA displayed the nearest results to those by GPS/levelling.

A Study on Geoid Height of Provinces in South Korea by Terrain correction of Earth Gravitational Models (EGMs의 지형보정에 따른 국내 지역별 지오이드고 연구)

  • Lee, yong-chang
    • Proceedings of the Korea Contents Association Conference
    • /
    • /
    • pp.942-946
    • /
    • 2007
  • The new gravity field combination models are expected to improve the knowledge of the Earth's global gravity field. This study evaluates six global gravity field models derived from gravimetry and altimetry surface data in a comparison with ground truth in South Korea. For calculating a more accurate estimate of the geoid heights from the height anomalies, the terrain corrections due to the terrain masses over geoid have considered, the model for the topographic correction is a spherical harmonic expansion of the ETOPO2 DTM model. Geoid heights obtained from GPS and levelling in land area of South Korea are compared with those from the EGMs. The results show that EIGEN-CG03C EGM and EIGEN-GL04C EGM displayed the nearest results to GPS/leveling, and also confirmed the importance of terrain correction for geoid height in case of the uneven topography.

  • PDF

Prediction of Submerged Effluent Transport Using Particle Tracking Model with Initial Mixing Characteristics (초기혼합특성을 고려한 입자추적 모형에 의한 수중방류 하수장의 거동 예측)

  • 김영도;강시환;서일원;오병철;주진규
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
    • /
    • /
    • pp.126-132
    • /
    • 2000
  • 하수처리장의 수중확산관에서 방류되는 부력제트는 초기혼합, 중력확장, 이송-확산 등의 과정이 시간적, 공간적으로 규모가 상이한 범위에서 일어나며, 하수방류 해역의 주변수 흐름은 지형특성과 조석의 영향을 받아 3차원적 비정상류 특성을 나타낸다. 이러한 부력제트의 거동을 모의하기 위해서는 일반적으로 근역과 원역을 분할하여 예측하는 방법을 사용하는데, 초기혼합 과정과 중력환장 과정을 예측하기 위해서는 정상상태는 가정한 특성길이 모형이나 제트적분 모형을 사용하고, 원역으로의 이송-확산 과정을 모의하기 위해서는 농도 모형이나 임자추적 모형등을 사용한다. (중략)

  • PDF

Determination of Hydraulic Parameters in Unconfined Sandy Aquifer in a Laboratory Scale (실내 자유면 사질 대수층의 수리상수 결정)

  • 김정석;김동주
    • Journal of the Korean Society of Groundwater Environment
    • /
    • v.6 no.3
    • /
    • pp.152-157
    • /
    • 1999
  • Oil leaked from underwound storage tanks and leachate from sanitary landfills have been known as contaminant sources of the high-quality groundwater resources. The mobility of contaminants in the aquifer largely depends on the groundwater flow and the determination of associated hydraulic parameters is essential for a proper remediation of contaminated grnundwater. This study aimed at determining an optimum set of hydraulic parameters for an unconfined sandy aquifer of a laboratory scale through comparison of various methods. Results showed that the specific yield obtained from gravity drainage experiment was an average of 0.20 with minor variations in aquifer depths. and the permeabilities obtained from Dupuit approximation and slug test gave similar values of 5.33 cm/min and 5.85 cm/min but the constant head method gave 0.17 cm/min, which is much ion than the other methods. This experimental evidence reveals that the permeability of the unconfined sandy aquifer could be accurately determined by Dupuit assumption or slug tut rather than by constant head method conducted for a disturbed separate soil column.

  • PDF

Nonhydrostatic Effects on Convectively Forced Mesoscale Flows (대류가 유도하는 중규모 흐름에 미치는 비정역학 효과)

  • Woo, Sora;Baik, Jong-Jin;Lee, Hyunho;Han, Ji-Young;Seo, Jaemyeong Mango
    • Atmosphere
    • /
    • v.23 no.3
    • /
    • pp.293-305
    • /
    • 2013
  • Nonhydrostatic effects on convectively forced mesoscale flows in two dimensions are numerically investigated using a nondimensional model. An elevated heating that represents convective heating due to deep cumulus convection is specified in a uniform basic flow with constant stability, and numerical experiments are performed with different values of the nonlinearity factor and nonhydrostaticity factor. The simulation result in a linear system is first compared to the analytic solution. The simulated vertical velocity field is very similar to the analytic one, confirming the high accuracy of nondimensional model's solutions. When the nonhydrostaticity factor is small, alternating regions of upward and downward motion above the heating top appear. On the other hand, when the nonhydrostaticity factor is relatively large, alternating updraft and downdraft cells appear downwind of the main updraft region. These features according to the nonhydrostaticity factor appear in both linear and nonlinear flow systems. The location of the maximum vertical velocity in the main updraft region differs depending on the degrees of nonlinearity and nonhydrostaticity. Using the Taylor-Goldstein equation in a linear, steady-state, invscid system, it is analyzed that evanescent waves exist for a given nonhydrostaticity factor. The critical wavelength of an evanescent wave is given by ${\lambda}_c=2{\pi}{\beta}$, where ${\beta}$ is the nonhydrostaticity factor. Waves whose wavelengths are smaller than the critical wavelength become evanescent. The alternating updraft and downdraft cells are formed by the superposition of evanescent waves and horizontally propagating parts of propagating waves. Simulation results show that the horizontal length of the updraft and downdraft cells is the half of the critical wavelength (${\pi}{\beta}$) in a linear flow system and larger than ${\pi}{\beta}$ in a weakly nonlinear flow system.