• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.225-233
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• 1999

Electrical resistivity of a rock-sample is dependant on not only formation factor of rock itself but also many parameters such as fluid type, measuring device, temperature, water saturation, electrical contact between electrode and core section, induced polarization, and frequency of electric source. In this study, we attempt to verify various affecting factors in core resistivity measurements and to find a better environment for core resistivity measurement. Particularly great attention has been paid to understanding the effects of temperature, water saturation, contact condition between sample and electrodes, and frequency of electric source. Precise measurement of resistivity can be achieved by utilizing silver paste for better contacts, taping samples for constant moisture contents, and using time-series resistivity data.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.199-205
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• 2002

In the resistivity method, the potential difference between two grounded electrodes is measured and this can be positive or negative. The apparent resistivity and the potential difference have the same polarity. Since the electric field is the gradient of the potential, the polarity of the potential difference depends on the direction of the electric field. If the direction of the vector connecting two grounded electrodes is the same to that of the electric field, the measured potential difference and the apparent resistivity become positive. If the opposite is the case, they become negative. In general, the primary electric field and the vector connecting two potential electrodes have the same direction in a surface resistivity method. In this case, the measured potential difference is always positive because the primary electric field is greater than the secondary field. Therefore, the apparent resistivity is always positive if noise is free and topography is flat. The secondary field component, however, can be greater than the primary field component along the vector connecting two potential electrodes in the cross-hole resistivity method. Furthermore, if the secondary electric field and the vector connecting two potential electrodes have an opposite direction, the apparent resistivity become negative. Consequently, the apparent resistivity may be negative in the region where the primary electric field component along the vector connecting two potential electrodes is very small.

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.110-112
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• 2002

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.231-234
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• 2002

Magnetic properties are investigated for top- and bottom-type spin valves of Si/SiO$_2$/NiO(60nm)/Co(2.5nm)/Cu(1.95nm)/Co(4.5nm)/NOL(t nm; Nano Oxide layer). The MR ratios of the bottom-type spin valves with NOL are larger than those of the top-type spin valves. However, the enhancement of the former is lower than the latter. Both of spin-valves also showed almost constant Ap and smaller p. Enhanced MR ratios of spin valves with NOL result mainly from small values of with constant Ap which due to specular diffusive electron scattering at NOL(NiO)/metal interfaces.

• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.6-10
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• 2005

This paper was studied on the damage behavior of stainless steel (STS 304) for gas boiler with specific resistance. The electrochemical polarization test of STS304 for gas boiler was carried out. And the anodic polarization and damage aspect, such as pitting corrosion, was considered. With being low specific resistance, the passive current density of STS 304 increases, passive region and pitting potential is low. Also, the patting aspect of STS304 In specific resistance $74{\Omega}{\cdot}m$ water little appears, the pitting number increases and the damage behavior, such as pitting aspect, gradually grow bigger with being low specific resistance.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.222-232
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• 1995

자기저항이란 외부 자기장에 의해 재료의 전기저항이 변화되는 현상을 일컫는다. Au와 같은 비자성도체 및 반도체 재료의 경우 외부에서 자기장이 가해지면 전도 전자가 Lorentz 힘을 받아 궤적이 변하므로 저항이 변화한다. 이러한 저항 변화 를 정상 자기저항(Ordinary Magnetoresistance, OMR)이라 하며 일반적으로 상당히 작은 저항의 변화를 나타낸다. 강자성도체 재료에서는 정상 자기저항 효과 외에도 부가적인 효과가 생긴다. 이는 스핀-궤도 결합에 기인한 효과로써 자기 저항은 강자성체의 자화용이축, 외부자계와 잔류간의 각도에 의존하며 이방성 자기저항(Anisotropic Magnetoresistance, AMR)이라 한다. AMR 비(%)는 일반적 으로 다음과 같이 정의된다. 즉 ${\Delta}{\rho}_{AMR}/{\rho}_{ave}=(\rho_{\|}-\rho_{T})/{\rho}_{ave}$로 여기서 $\rho_{\|}$는 자기장의 방향이 전류의 방향과 같을 때의 비저항 이고 $\rho_{T}$는 서로 수직일 때이며 ${\rho}_{ave}=(\rho_{\|}-\rho_{T})/3$이다. 기존의 MR 센서나 자기재생헤드(magnetic read head)에 사용되는 퍼머로이계 합금의 AMR 비는 상온에서 약 2% 정도의 저항변화를 보인다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.113-119
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• 2019

This study aims at the analysis using the Resistivity Estimation Model (REM) to examine the effect of specimen size on the measurement of electrical resistivity. In the experiment, specimens of concrete were fabricated and the apparent resistivity was measured for each electrode interval. The apparent resistivity measured was found to be distorted in the apparent resistivity as the specimen size became smaller and closer to the outside (edge). As a result of comparing the experimental and analysis values, it is expected that REM can be used to examine the effect of the size of the specimen.

• Journal of the Korean Geophysical Society
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• v.1 no.1
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• pp.51-58
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• 1998

A numerical program has been developed to model 2-D resistivity responses for a pole-pole array configuration in cross-hole resistivity measurements. Apparent resistivity and secondary potential were computed using the program for a cylindrical inhomogeneity in an uniform host medium excited by a point source of current in a borehole. Surprisingly apparent resistivity in the receiver hole turns out to be lower than the one of surrounding medium regardless of the conductivity of cylindrical inhomogeneity. Using only cross-hole data, therefore, it is impossible to interpret the conductivity of inhomogeneity. To overcome this problem, 3-D measurement and interpretation are necessary. If 3-D data acquisition is impossible, inline data should be used to get the information about the conductivity of inhomogeneity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.267-269
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• 2003

반도체 웨이퍼 및 각종 박막의 면/비저항(sheet/resistivity resistance)의 측정에 비교적 간단히 측정할 수 있고 측정정확도가 높은 4탐침(four-point probe)방법이 널리 사용되고 있다 또한 4탐침 측정방법은 높은 분해능의 contour map작성과 ion implantation의 doping accuracy 및 doping uniformity의 측정에도 사용된다. 최근 재료의 소형, 박막화 경향으로 볼 때 정확한 비저항 측정의 필요성이 요구되고 있으며 이에 따라 4탐침 측정기술인 single 및 dual configuration method로 실리콘 웨이퍼에 대한 비저항의 측정 정확도를 고찰한 결과 dual configuration 측정방법이 single configuration측정 방법에 비하여 정밀 정확도가 더 좋은 것으로 고찰되었다.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.37-39
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• 2007

금속의 전기 비저항 측정방법은 일반적으로 4단자, van der Pauw, Four-Point Probe(FPP), eddy current 방법 등이 있다. 이들의 측정방법들은 각각 다르지만 동일한 시료에 대한 전기 비저항 측정값은 거의 같은 결과를 나타내어 야 한다. 금속 전기 비저항의 정밀측정에 대한 연구를 위하여 비자성 금속인 STS 316 시료를 선정하여 측정한 결과 4단자와 van der Pauw 방법으로 측정된 비저항은 각각 $75.86{\mu}g\Omega{\cdot}cm$(2.273 %IACS), $75.80{\mu}g\Omega{\cdot}cm$(2.275 %IACS)이며, 측정 불확도는 0.25 %로서 거의 동등한 결과를 나타냈고, Four Point Probe(FPP) 방법으로 측정된 비저항은 $75.36{\mu}g\Omega{\cdot}cm$(2.288 %IACS), 측정 불확도는 0.45 %, eddy current 방법으로 측정된 비저항은 $76.63{\mu}g\Omega{\cdot}cm$(2.25 %IACS), 측정 불확도는 0.64 %로 나타났다.