• 대한기계학회논문집A
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• 제24권12호
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• pp.2995-3002
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• 2000

The remaining life estimation for the aged components in power plants as well as chemical plants are very important beacuse mechanical properties of the components are degraded with time of service exposure in high temperature. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components nondestructive techniques are needed to estimate the degradation. In this study, test materials with 4 different degradation levels were prepared by isothermal aging heat treatment at 630$\^{C}$. And the DC potential drop method and destructive methods such as tensile, K(sub)IC and hardness tests were used in order to evaluate the degradation of 1-Cr-1Mo-0.25V steels. The objective of this study is to investigate the possibility of the application of DCPD method to estimated the material degradation, and to analyse the relationship between the electrical relationship between the electrical resistivity and the degree material degradation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1105-1107
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• 1999

The purpose of termination for high voltage tests of XLPE power cable is to prevent flashover during the breakdown test of specimen as well as to withstand the specified voltage between its conductor and screen without failure. For easier treatment and simpler construction of testing termination, resistivity grading method using semi-conductive material was employed. Based on the fundamental theory, its failure characteristics by changing the resistivity of semi-conductive material on the insulation surface was investigated. With two layers construction by difference resistivity on their surfaces, much improved result than that of one resistivity was obtained through the experiment for MV cable.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.55-58
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• 2002

In this paper, the volume resistivity properties of silicone rubber investigated due to temperature dependence. And the measurement of volume resistivity is measured from 1, 5 and 10 minutes when the each applied voltage, for example, DC 100[V], 250[V], 500[V] and 1000[V], is applied. according to the step voltage application method. As a result, The volume resistivity is higher high voltage than low voltage at the room temperature, but is higher low voltage than high voltage at high temperature.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.107-112
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• 2007

To establish the reinforce region and technique through the embankment dike after identifying the region of seawater inflow, we carried out small-loop electromagnetic (EM) survey, electrical resistivity survey and refraction seismic method. We also analyzed the distribution of electrical conductivity in reservoir with depth every two month and monitored water level variations with tidal variation in four observation wells located at seaside and reservoir side in order to analyze the relationship with survey results. From both the cross-correlation between tidal and water level variation at four wells and the distribution of electrical conductivity in reservoir with depth, the major portion of seawater inflow are identified through the embankment dike. From electromagnetic and electrical resistivity survey results, it was found that the seawater inflow were happened through several small regions at seaside and became wider near reservoir side. The 2-D inversion sections of refraction seismic method showed that the pebble-bearing sand layer is spread over the whole region with two to four width. From the this study, small-loop EM, electrical resistivity and refraction seismic surveys accompany with the distribution of electrical conductivity in reservoir with depth and the monitoring results for water level variations are revealed to be effective to identify seawater inflow pathway through embankment dike and to establish the reinforce region and technique through the embankment dike.

• 한국표면공학회지
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• 제44권6호
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• pp.264-268
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• 2011

The Molybedenium thin film is generally used on back contact material of CIGS solar cell due to low electrical resistivity and stable thermal expansion coefficient. The Mo thin films deposited on si wafer by the magnetron sputtering method. The research focused on the variation of electrical resistivity of films which deposited with various working pressure at the target power of 2.0 kW(8.4 W/). The lowest resistivity of Mo thin film showed $9.0{\mu}O$-cm at pressure of 1.5 mTorr. However, working pressure increasing up to 50 mTorr, resistivities were highly increased. The results showed that the conductivity of Mo films depended on growing structures and defects in deposition process. Surface morphology, porosity, grain size, oxidation, and bonding structures were analysed by SEM, AFM, spectroscopic ellipsometry (SE), XRD, and XPS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.154-156
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• 1996

A new method for electric resistivity tomography(ERT) is developed for geophysical inverse problems by adapting the sensitivity analysis. The outputs of the potential electrodes are computed using two dimensional finite element method in the wave number space by Fourier transforming the governing equations. The resistance distribution in the region of interests, which makes the computed potential distribution coincide with the measured potential, is found by minimizing the objective function using an optimization method. In this process the sensitivity analysis is introduced in order to compute the derivatives of the objective function. And an adjoint variable method is used to save the computational efforts for sensitivity coefficients.

• 지질공학
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• 제17권2호
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• pp.271-277
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• 2007

천매암 및 편암으로 구성된 기지의 절개사면에서 제시된 이상대는 사면 하단부에 설정된 전류원과 상단부의 전위전극으로 하는 단극-쌍극자 배열을 이용한 전기비저항 토모그래피 방식으로 파악되었다. 해석 방법은 각 측선에서 얻어진 측정 자료를 가지고 3차원 전기비저항 역산 방법으로 하였다. 각 측선에 따른 영상들을 볼 때, 사면의 중앙부에 위치한 단층은 사면에 거의 수직인 방향으로 연장된 영상들로 제시되었다. 수치모델링 결과에서 이상대의 영상들은 절개사면에서 제시된 위치에 매우 정확한 결과들로 보여 주었으며, 단층은 절개사면으로부터 거리가 멀어질수록 지표로부터 그 심도가 깊어지는 경향으로 나타났다.

• 한국도로학회논문집
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• 제19권3호
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• pp.57-63
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• 2017

PURPOSES : The pole electrode method damaged the concrete pavement on inserting the electrode into the pavement surface. This study examined the feasibility of the flat electrode method to observe the concrete pavement instead of the pole electrode method and analyzed the resistivity characteristics of the concrete by performing laboratory tests. METHODS : The resistivity of the concrete specimens manufactured with three different mixing ratios (38.50%, 39.50%, and 40.50%) were measured using the pole and flat electrode methods according to the concrete age (7 and 28 days) and electrode spacing (20 mm, 30 mm, and 40 mm). RESULTS :In both pole and flat electrode methods, the resistivity increased with increasing fine aggregate proportion regardless of the concrete age. The resistivity measured at a concrete age of 28 days was slightly larger than that measured at 7 days. In the case of a concrete age of 7 days, the resistivity measured by the flat electrode method was larger than that measured by the pole electrode method. The difference disappeared at 28 days. CONCLUSIONS :The results suggest that the flat electrode method can replace the pole electrode method because the resistivity measured by both methods was similar. Hence, the development of a technology to apply the flat electrode method to actual concrete pavement is necessary.

• 한국방재학회 논문집
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• 제3권4호
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• pp.145-151
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• 2003

생활폐기물 및 산업폐기물은 인간의 활동으로부터 배출되며 소각법 혹은 매립법 또는 2가지 방법을 동시에 이용하여 처리되고 있다. 특히 매립법은 침출수로 인하여 매립지가 있는 지역의 지하수계를 심각하게 오염시켜 환경재해를 발생시키고 있다. 따라서 오염지역의 침출수 오염특성을 3차원적으로 조사하여 환경재해를 최소화하는 것이 중요하다. 본 연구는 비위생 매립지인 충주시 노은 매립장의 3차원적 침출수 오염특성을 조사하였다. 조사를 위한 1개 측선의 방향은 주된 매립지 경계와 평행하도록 설치하였다. 노은 매립장을 탐사한 결과 가장 상부층은 안정화가 완전하게 진행되었으나 가장 하부층은 부분적으로 침출수가 일부 존재하는 것으로 분석되었다.

• 지질공학
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• 제18권3호
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• pp.245-255
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• 2008

제체의 안전진단을 위해 많이 적용되고 있는 전기비저항 탐사 자료 해석의 효율성을 높이기 위해, 제체의 상태에 따른 전기비저항 물성의 변화 양상을 실내시험 및 실측 자료의 분석을 통해 파악하였다. 이를 위해 제체의 심벽 재료와 유사한 성질을 가지는 kaolinite를 이용하여 압밀조건에 따른 비저항 변화를 살펴보았다. 그 결과, 일축 압축에 의하여 전단강도가 떨어지는 경우에는 함수량에 관계없이 비저항 값이 상승하는 것으로 나타났다. 이러한 사실은 제체 내의 심벽부분에 공극이 크게 발달하는 경우, 함수량에 상관없이 비저항은 상승할 가능성이 있다는 것이다. 코어부의 누수 현상과 관련한 이러한 관측은, 단순히 비저항이 낮은 곳만을 탐지하는 것이 누수대역을 조사하는데 있어 목표가 되어서는 안 된다는 것을 암시한다. 또한 전기비저항 물성이 지반 강성도와 갖는 상관성을 파악하기 위해, 제체에 대한 시추를 통해 표준관입시험을 수행하였다. 마지막으로, 제체 보강을 위해 수행된 그라우팅 효과의 검증을 위해, 그라우팅에 따른 비저항변이 알고리듬을 제안하고, 실제 관측 자료와의 비교를 통해 알고리듬을 파악하였다.