Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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Three-dimensional Electromagnetic Modeling in Frequency Domain

주파수영역 전자법의 3차원 모델링

  • Jang, Hannuree (Green Energy Research Institute, Sejong University, Energy Resources Institute, Pukyong National University) ;
  • Kim, Hee Joon (Department of Energy Resources Engineering, Pukyong National University)
  • 장한누리 (세종대학교 그린에너지연구소, 부경대학교 에너지자원연구소) ;
  • 김희준 (부경대학교 에너지자원공학과)
  • Received : 2013.05.10
  • Accepted : 2014.07.08
  • Published : 2014.08.31
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Abstract

Development of a modeling technique for accurately interpreting electromagnetic (EM) data is increasingly required. We introduce finite difference (FD) and finite-element (FE) methods for three-dimensional (3D) frequency-domain EM modeling. In the controlled-source EM methods, formulating the governing equations into a secondary electric field enables us to avoid a singularity problem at the source point. The secondary electric field is discretized using the FD or FE methods for the model region. We represent iterative and direct methods to solve the system of equations resulting from the FD or FE schemes. By applying the static divergence correction in the iterative method, the rate of convergence is dramatically improved, and it is particularly useful to compute a model including surface topography in the FD method. Finally, as an example of an airborne EM survey, we present 3D modeling using the FD method.

전자탐사 자료로부터 지하구조를 정확하게 해석하기 위해서는 적절한 모델링 기술이 필요하다. 본보에서는 주파수영역 전자탐사 3차원 모델링에 유한차분법이나 유한요소법을 이용할 경우 필요한 기초 사항에 대해 소개한다. 인공송신원에서 특이성을 피하기 위해 지배방정식을 전기장의 2차장으로 정식화하고 그 결과 유도되는 연립방정식을 풀기 위한 반복해법과 직접해법에 대해 설명한다. 그리고 반복해법에 발산보정을 도입하면 그 수렴성을 대폭 향상시킬 수 있으며, 이는 유한차분법에서 지형효과를 모델링할 때 특히 유용하다. 마지막으로 여기서 소개한 유한차분법을 이용한 3차원 모델링 알고리듬을 항공전자탐사에 적용한 예를 보여준다.

Keywords

References

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