• Title/Summary/Keyword: DC-resistivity method

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Safety Evaluation of Rock-Fill Dam by Seismic(MASW) Method (사력댐의 안정성평가를 위한 표면파탐사(MASW)의 활용성)

  • 정해상;오영철;방돈석;안상로
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.359-364
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    • 2003
  • For safety evaluation of a rock-fill dim, it is often necessary to investigate spatial distribution of weak zones such as fracture. Both DC-resistivity survey and seismic(SASW) method are usually used for the purpose. Recently, Multichannel analysis of surface waves(MASW) method which makes up for the weak point of SASW method is developed and the site examination which is simple came to be possible comparatively. In order to obtain 2-D shear-wave velocity(Vs) profile along the dam axis that can be associated with dynamic properties of filled materials, MASW method was adapted. Then, DC-resistivity survey and drilling survey were performed to compare with each results. We confirmed that the MASW method and DC-resistivity survey show complementary result that corresspond with drilling result. Therefore, MASW method is an efficient method for dynamic characterization of dam-filling materials and also the combination of related methods such as DC-resistivity can lead to an effective safety evaluation of rock-fill dam.

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Optimization method of DC resistivity data acquisition system using multi-electrode arrays (다전극 배열을 사용한 DC 저항률 취득 시스템의 최적화 방법)

  • Boo, Chang-Jin;Kim, Ho-Chan
    • Proceedings of the KIEE Conference
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    • 2006.07d
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    • pp.1795-1796
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    • 2006
  • The accurate measurement of soil resistivity and earthing system resistance is fundamental to electrical safety. However, geological and meterological factors can have a considerable effect on the accuracy of conventional measurements and the validity of the measurement methods. This paper presents optimization method of dc resistivity data acquisition system using multi-electrode arrays.

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Geophysical Exploration on Unconformity-type Uranium Deposit in Athabaska Basin, Canada (캐나다 아타바스카 분지 부정합형 우라늄광상 물리탐사 사례)

  • You, Young-June;Kim, Jae-Chul
    • 한국지구물리탐사학회:학술대회논문집
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    • 2009.05a
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    • pp.73-87
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    • 2009
  • Geophysical survey for unconformity-type uranium deposit applied to this study area in Athabaska Basin, Canada were carried out airborne TEM and magnetic, resistivity-induced polarization (DC-IP), puser seismic reflection and well-logging method. The results of airborne survey interpreted the lithological boundary, geological structures, and conductors. Also, these results decided to main targets for ground DC-IP survey. The Low resistivity and the high chargeability slices of 3D modeling interpreted from DC-IP survey response for conductors related to hydrothermal alteration zones and fault-controlled graphitic zones occurring at the unconformity-type uranium deposit, and they confirmed by diamond drilling. Seismic results interpreted to lake bottom surface, alluvium layer and intra-sandstone faults. We suggest the resonable field data acquisition of DC-IP method on the land or the lake in Athabaska Basin.

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Inversion of Time-domain Induced Polarization Data by Inverse Mapping (역 사상법에 의한 시간영역 유도분극 자료의 역산)

  • Cho, In-Ky;Kim, Yeon-Jung
    • Geophysics and Geophysical Exploration
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    • v.24 no.4
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    • pp.149-157
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    • 2021
  • Given that induced polarization (IP) and direct current (DC) resistivity surveys are similar in terms of data acquisition, most DC resistivity systems are equipped with a time-domain IP data acquisition function. In addition, the time-domain IP data include the DC resistivity values. As such, IP and DC resistivity data are intimately linked, and the inversion of IP data is a two-step process based on DC resistivity inversions. Nevertheless, IP surveys are rarely applied, in contrast to DC resistivity surveys, as proper inversion software is unavailable. In this study, through numerical modeling and inversion experiments, we analyze the problems with the conventional inverse mapping technique used to invert time-domain IP data. Furthermore, we propose a modified inverse mapping technique that can effectively suppress inversion artifacts. The performance of the technique is confirmed through inversions applied to synthetic IP data.

DC Potential Drop Method for Evaluating Material Degradation

  • Seok, Chang-Sung;Bae, Bong-Kook;Koo, Jae-Mean
    • Journal of Mechanical Science and Technology
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    • v.18 no.8
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    • pp.1368-1374
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    • 2004
  • The remaining life estimation for the aged components in power plants as well as chemical plants are very important because mechanical properties of the components are degraded with in-service exposure time in high temperatures. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components, nondestructive techniques are needed to evaluate the degradation. In this study, test materials with several different degradation levels were prepared by isothermal aging heat treatment at $630^{\circ}C$. The DC potential drop method and destructive methods such as tensile and fracture toughness were used in order to evaluate the degradation of 1Cr-1Mo-0.25V steels. In this result, we can see that tensile strength and fracture toughness can be calculated from resistivity and it is possible to evaluate material degradation using DC potential drop method, non-destructive method.

Response of coal rock apparent resistivity to hydraulic fracturing process

  • Song, Dazhao;Wang, Enyuan;Qiu, Liming;Jia, Haishan;Chen, Peng;Wei, Menghan
    • Geomechanics and Engineering
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    • v.14 no.6
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    • pp.581-588
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    • 2018
  • In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

Effects of Sputtering Power and Oxygen Flow Rate on the Electrical Properties of ATO Thin Films Made by DC Magnetron Sputtering (DC Magnetron Sputtering 법에 의해 ATO 박막 제조시 스퍼터전력 및 산소유량이 전기적 성질에 미치는 영향)

  • Lee, Hwan-Soo;Lee, Hae-Yong;Yoon, Cheon
    • Korean Journal of Materials Research
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    • v.9 no.5
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    • pp.533-537
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    • 1999
  • ATO(Sb doped $SnO_2$) thin films whose thicknesses were 600, 1100 and $2100\AA$ were prepared by DC magnetron sputtering method. They showed the lowest resistivity at DC sputtering power 0.24kW and had lower resistivity with increasing thickness. The power dependence of resistivity among ATO thin films was also different with thickness. The increase of carrier concentration in ATO thin films was responsible for the decrease of resistivity with thickness increase. ATO thin films which were prepared at 30sccm oxygen flow rate showed a great change of sheet resistance under 1M HCl solution. The investigation of SAM(Scanning Auger Microprobe) revealed that oxygen atomic percentage on the surface of ATO thin films was changed. The decrease of sheet resistance also occurred when ATO thin films, prepared at 30sccm oxygen flow rate, were exposed to air for a long period of time. For this reason, it was considered that the desorption of oxygen on ATO surface was accelerated by HCl.

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Properties of ITO Transparent Conducting Film by DC Magnetron Sputtering Method (DC 마그네트론 스퍼터법에 의한 ITO 투명전도막 특성)

  • Park, Kang-Il;Kim, Byung-Sub;Lim, Dong-Gun;Park, Gi-Yub;Kwak, Dong-Joo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05c
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    • pp.95-98
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    • 2003
  • Tin doped indium oxide(ITO) films, which is widely used as a transparent conductor in optoelectronic devices such as solar cell, liquid crystal display, plasma display panel, thermal heater, and other sensors, were prepared by using the capacitively coupled DC magnetron sputtering method. The influence of the substrate temperature, working gas pressure and deposition time on the electrical, optical and morphological properties were investigated experimentally. ITO films with the optimum growth conditions showed resistivity of $2.36{\times}10^{-4}(\Omega}-cm$ and transmittance of 86.28% for a film 680nm thick in the wavelength range of the visible spectrum.

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Evaluation Technology of Degradation of Metallic Alloy using Electrical Resistivity (전기비저항을 이용한 금속합금 열화도 평가기술)

  • Nahm, Seung-Hoon;Yu, Kwang-Min;Ryu, Jae-Cheon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.5
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    • pp.532-541
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    • 2001
  • Developments of nondestructive evaluation techniques for reduction of strength or toughness by aging of material have been carried out, and the method using electrical resistivity is one of them. In this study, to examine the application of electrical resistivity to the evaluation of degradation of metallic alloy, ten different non-magnetic materials were selected as test materials. Electrical resistivities measured by DC two-point probe method and those measured by non-contact type eddy current method were compared with each other. In addition, to examine the application possibility of four-point probe technology in field, the electrical resistivities for 1Cr-lMo-0.25V steel measured by DC two-point probe method and four-point probe method were compared with each other Differences between two measured values for the 1Cr-1Mo-0.25V steel were 0.6%. Therefore, the four-point probe method can be applied to the estimation of the degradation of metallic alloy. ect.

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Preparation of ATO Thin Films by DC Magnetron Sputtering (II)Electrical Properties (DC Magnetron Sputtering에 의한 ATO 박막의 제조(II)전기적 특성)

  • Yoon, C.;Lee, H.Y.;Chung, Y.J.;Lee, K.H.
    • Journal of the Korean Ceramic Society
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    • v.33 no.5
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    • pp.514-518
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    • 1996
  • Sb doped SnO2(ATO: Antinomy doped Tin Oxide) thin films were prepared by a DC magnetron spttuering method using an oxide target and the electrical characteristics of ATO films were investigated. The experimen-tal conditions are as follows :Ar flow rate ; 0~100 sccm deposition tempera-ture ; 250~40$0^{\circ}C$ DC sputter powder ; 150~550W and sputteing pressure ; 2~7 mTorr, The thickness of depositied ATO films were 600$\AA$~1100 $\AA$ ranges. The resistivity of ATO films was decreased due to the increase of the crystallinity of ATO films with deposition temperature. The decrease of carrier concentration of films with the increase of oxygen flow rate and working pressure is responsible for the increase of resistivity. Increasing of sputtering power raised the resistivity of films by decreasing the carrier mobility.

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