• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.212-215
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• 2001

남악지역에 분포하는 조간대 퇴적층의 층서구조와 퇴적심도 및 기반암의 단열구조를 파악하기 위한 전기비저항탐사를 실시하였다. 조간대 퇴적물에서 비저항은 하부로 갈수록 증가하며 대부분 3.0 Ohm-m이하의 비저항으로 고비저항의 기반암의 기반암과 뚜렷한 경계를 보여준다. 퇴적층의 층후는 퇴적지 중앙부에서 30m를 최대로 북쪽 (고해안선)과 남쪽 (영산강)으로 갈수록 감소하는 경향을 보여주는데 선행 조사된 시추결과와 일치한다. 일부 지역의 전기비저항 해석단면과 시추단면에서 견고한 점토질 (stiff)의 지층이 분포하는데 이 지층은 북서-남동 방향의 고해안선과 나란하게 분포한다. 이것은 퇴적물을 공급한 흐름의 방향과 조간대의 확장방향이 북서-남동 방향임을 지시한다. 기반암의 단열구조로 판단되는 저비저항대는 조사지역의 동부에 집중되어 있으며 단열대의 연장방향은 북서-남동 방향이 우세하다.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.194-199
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• 1997

We fabricated MIM (Metal-Insulator-Metal) antifuses with Al/a-Si/Mo structure and then examined the I-V characteristics and on-state resistance distribution of antifuses. The leakage current of antifuses is below $1Pa/{\mu}m^2$, and programming voltage lies within 10 to 11 V. After programming, on-resistance of antifuses is mostly 10-20$\Omega$ and 20% of these have above 100$\Omega$. In order to reduce on-resistance and the deviation of this distribution, we tried to inject current again into already programed antifuses (we call this re-programming method). From this method, the resistance of antifuses with above 100Ω can be reduced to below 50$\Omega$. When antifuses are programmed by re-programming method, these antifuses have more uniform and lower on-resistance than programmed with one-pulse.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.117-128
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• 2016

Installation of earth grounding system is essential to ensure personnel safety and correct operation of electrical equipment. Earth parameters, especially, soil resistivity has to be determined in designing an efficient earth grounding system. The most common applied technique to measure soil resistance is Wenner four-point method. Implementation of this method is expensive, time consuming and cumbersome as large set of measurements with variable electrode spacing are required to obtain a one dimensional resistivity plot. It is advantageous to have a method which is of low cost and provides fast measurements. In this perspective, electrical resistance tomography (ERT) is applied to estimate subsurface resistivity profile. Electrical resistance tomograms characterize the soil resistivity distribution based on the measurements from electrodes placed in the region of interest. The nonlinear ill-posed inverse problem is solved using iterated Gauss-Newton method with Tikhonov regularization. Through extensive numerical simulations, it is found that ERT offers promising performance in estimating the three-dimensional soil resistivity distribution.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.3-5
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• 1997

지구 물리학이나 의공학 분야등에서 이용되왔던 전기비저항 탐사법은 관심 영역에 전류 입력을 가한 후, 그에 대한 전압 응답을 측정하여 관심 영역 내의 전기비저항 분포를 규명하는 방법으로서 역해석 문제의 범주에 포함된다. 따라서 일반적인 역해석 문제가 지니고 있는 해의 존재성, 유일성, 그리고 측정 데이터에 대한 해의 연속적 의존성이라는 기본적 문제들을 가지게된다. 이러한 역해석 문제의 해결에는 정확한 정해석 풀이법과 효율적인 역해석 방법이 요구되어진다. 본 논문에서는 정해석 방법으로 유한요소법을, 역해석 방법으로는 전체 최적점을 발견할 가능성이 높은 유전 알고리즘을 최적화 방법으로 사용하였다. 기존의 역해석 문제의 해결책으로 제시되어왔던 기울기 방법에 기반한 결정론적 최적화 알고리즘들이 지니고 있는 국소해로의 수렴, 즉 단순한 전기비저항 분포의 불연속성 확인이라는 한정된 정보의 획득을 넘어서 실제 전기비저항 분포와 가장 가까운 분포는 전체 최적점 근처에서 발견될 수 있음을 보이고자 한다. 이러한 전기비저항 분포의 역해석적인 규명을 간단한 2차원 수치해석문제를 풀어보므로서 확인해본다.

• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.211-218
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• 2007

In this study, vertical electrical sounding (VES) data and ordinary kriging are used to identify the alluvial depth of each area that Korea Resources Corporation (KORES) conducted groundwater survey at Miryang area in Gyeongsangnam-do and Pocheon area in Gyeonggi-do from 2003 to 2004. To verify the applicability of VES data to ordianry kriging, regression analysis of VES data versus drillhole data is conducted. Comparing the alluvial depth distributions using ordinary kriging with existing drillhole data, the result shows that the depth distributions are reasonably depicted along with the topography and the basin. So, the ordinary kriging of VES data is useful to identify the alluvial depth distributions.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.83-91
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• 2003

광대역 스펙트럼을 갖는 신호의 송, 수신을 위한 안테나는 분산 및 단부(end points)에서의 전류 반사가 최소로 되어야 한다. 이를 위해 안테나 상에 저항을 적절히 분포시키는 방법을 소개하고, 그 방법을 사용한 대표적인 펄스 송, 수신안테나의 특성을 살펴보고자 한다. 그리고 비선형적으로 분포된 저항을 갖는 다이폴 안테나의 ps 전자기 펄스 송, 수신 특성을 펄스폭, 안테나 길이와 형상 등을 변수로 하여 시간영역 해석을 통해 엄격히 분석한다.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2005.05a
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• pp.84-84
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• 2005

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.10
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• pp.694-701
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• 1988

Distributed-type railguns are designed to maintain the armature current and the length between the armature and the current-feed region nearly constant with time. This paper deals with factors affecting current distribution, effective resistance and effective skin depth in the rail of a distributed-type railgun. Analytical solutions for the current distributions and resistance in the rail are presented for a simple two-dimensional model under steady-state contions. For diffusion limited current, it is found that effective rail resistance is proportional to the square root of the relative velocity, the permeability of the rail and the length between the armature and that effective skin depth of the rail is proportional to the square root of the length and inversely proportional to the square root of the permeability, the conductivity and the velocity.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1106-1111
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• 2014

This paper has a purpose to find out the characteristics of pressure distribution according to the POD shape installed in the Hydrofoil vessel, using the CFD. The results showed that as we cut the POD cross-section's basic shape along the x-axis from 0 to 8cm, the viscous resistance had decreased, but then the pressure resistance had increased modestly. However, the cutoff length of POD cross-section shape has close to 9cm, the viscous drag had increased and the pressure drag had decreased. As a result, we found out that the pressure resistance made more effects in POD shape than the viscous resistance, and the total resistance decreased near the 9cm of cutoff length.

• Geophysics and Geophysical Exploration
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• v.13 no.2
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• pp.175-180
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• 2010

The small loop electromagnetic (EM) method is a fast and convenient geophysical tool which can provide resistivity distribution of shallow subsurface. Especially, it can be a useful alternative of resistivity method in a very conductive environment such as a reclaimed saline land. We applied the multi-frequency small loop EM method for the site investigation of reclaimed saline land. We inverted the measured EM data using one dimensional (1D) inversion program and merged to obtain three dimensional (3D) resistivity distribution over the survey area. Finally, comparing he EM results with the drill log and measured soil resistivity sampled at 16 drill holes, we can define the site character such as thickness of landfill, salinity distribution, and etc.