• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.9-14
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• 2006

Estimations of depth, magnetic orientation, and strength of dipole moments aid discrimination between unexploded ordnance (UXO) and non-UXO using magnetic surveys. Such estimations may be hindered by geologic noise, magnetic clutter, and overlapping tails of nearby dipole fields. An improved method of inversion for anomalies of single or multiple dipoles with arbitrary polarization was developed to include intra-inversion filtering and estimation of background field gradients. Data interpolated to grids are flagged so that only nodes nearest to measurement stations are used. To apply intra-inversion filtering to such data requires a gapped filter. Moreover, for data with significant gaps in coverage, or along the edges or corners of survey areas, intra-inversion filters must be appropriately modified. To that end, edge-adaptive and gapped gradient-nulling filters have been designed and tested. Applications are shown for magnetic field data from Chongcho Lake, Sokcho, Korea and the U. S. Army's Aberdeen Proving Ground in Maryland.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.112-115
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• 2003

쓰레기매립장의 침출수 누출 탐지를 위한 물리탐사법은 침출수의 전기전도도를 대상으로 한 전기탐사법이 주로 적용되어 왔다. 이 연구는 제주도에 위치한 비위생매립지를 대상으로 주변 수리지질환경 파악을 위한 전기비저항 탐사와 더불어 매립장 경계부와 토양층을 통한 침출수 누출 영역을 효율적으로 규명하기 위하여 다중주파수를 이용한 소형루프 전자탐사를 병행하여 수행하였으며, 아울러 오염지역의 천부 지하수 유동 방향을 추정하기 위하여 침출수의 유동에 의해 발생될 수 있는 자연전위를 모니터링 하였다. 전기비저항 탐사 및 자연전위 모니터링 결과 매립지 주변을 통한 침출수의 누출 가능성은 거의 없는 것으로 나타났으며, 이는 주변 하천에서 정기적으로 실시한 수질 분석 결과와 일치된다. 또한 소형루프 전자탐사 자료에 대하여 공간 필터링 및 1차원 역산법을 적용한 결과 매립장 경계부의 위치 및 매립장 내부의 심도별 매립물에 의한 저비저항 이상대를 효과적으로 도출 할 수 있었다.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.46-53
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• 2010

A Compton X-ray backscatter technique has been developed to quantitatively assess impact damage in quasi-isotropic laminated composites made by a drop-weight tester. X-ray backscatter imaging system with a slit-type camera is constructed to obtain a cross-sectional profile of impact-damaged laminated composites from the electron-density variation of the cross section. A nonlinear scattering model based on Boltsman equation is introduced to compute Compton X-ray backscattering field for the defect assessment. An adaptive filter is also used to reduce noises from many sources including quantum noise and irregular distributions of fibers and matrix in composites. Delaminations masked or distorted by the first delamination are detected and characterized effectively by the Compton X-ray backscatter technique, both in width and location, by application of error minimization algorithm.

• Geophysics and Geophysical Exploration
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• v.6 no.3
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• pp.143-152
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• 2003

Among the various geophysical approaches to identify the leakage of leachate with conductivity variation, conventional electrical resistivity survey has been mainly used at waste landfill. We adopted small-loop electromagnetic (EM) survey using multi-frequencies in parallel with electrical resistivity survey to delineate the leakage of leachate through the shallow soil layer at a waste landfill in Jeju Island, and also with self-potential monitoring to detect the streaming potential produced by the movement of leachate. There were no evidences of leakage from waste landfill according to the results of the electrical resistivity survey and SP monitoring, and it was also true from the results of water quality analysis at stream around waste landfill periodically. On the other hand, the results of one-dimensional inversion of spatially-filtered small-loop EM survey data showed the anomalous zone of low resistivity with depth both around and inner waste landfill.