• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.241-244
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• 2007

Cement-grouts are injected into limestone cavities beneath the road in the project area, in order to improve strength and reduce permeability; the extent to which grout has penetrated in cavities need to be monitored in order to determined effectiveness of cement-grout. Geophysical approaches, offer great potential for monitoring the grout injection process in a fast and cost-effective way as well as showing whether the grout has successfully achieved the target. This paper presents the ability of surface electrical resistivity to investigate the verification of the grout placement. In order to image the cement-grout, time-lapse surface electrical resistivity surveys were conducted to compare electrical resistivity images before and after injection. Cement-grout was imaged as anomalies exhibiting low resistivity than the surrounding rocks. In accordance with field monitoring, laboratory study was also designed to monitor the resistivity changes of cement-grout specimens with time-lapse. Time-lapse laboratory measurements indicated that electrical methods are good tool to identify the grouted zone. Pre-and post grouting electrical images showed significant changes in subsurface resistivity at grouted zone. The study showed that electrical resistivity imaging technology can be a useful tool for detecting and evaluating changes in subsurface resistivity due to the injection of the grout.

• 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.

• Smart Structures and Systems
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• 제16권4호
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• pp.667-681
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• 2015

The scour induced by strong currents and wave action decreases the embedded length of monopiles and leads to a decrease of their structural stability. The objective of this study is the development and consideration of scour-monitoring techniques for offshore monopile foundations. Tests on physical models are carried out with a model monopile and geo-materials prepared in a cylindrical tank. A strain gauge, two coupled ultrasonic transducers, and ten electrodes are used for monitoring the scour. The natural frequency, ultrasonic reflection images, and electrical resistivity profiles are obtained at various scour depths. The experimental results show that the natural frequency of the model monopile decreases with an increase in the scour depth and that the ultrasonic reflection images clearly detect the scour shape and scour depth. In addition, the electrical resistivity decreases with an increase in scour depth. This study suggests that natural frequency measurement, ultrasonic reflection imaging, and electrical resistivity profiling may be used as effective tools to monitor the scour around an offshore monopile foundation.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.173-178
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• 2007

Time-lapse electrical resistivity measurements have been made in a scale model experiment for geological $CO_2$ sequestration in aquifer. Three types of $CO_2$ injection are tested in a water tank filled with glass beads. These are $CO_2$ dissolved into filtered tap water, $CO_2$ gas, and mineral oil. The mineral oil is a substitute for liquid phase of supercritical $CO_2$. For reconstructing three-dimensional resistivity images, we measure potential differences at 32 potential dipoles on the top surface of the tank due to two current dipoles on the front and back sides. The resultant resistivity images clearly show the movement of injected $CO_2$ in aquifer.

• 지질공학
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• 제17권1호
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• pp.49-55
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• 2007

전기비저항 탐사에 있어서 지하에 분포하는 이상대를 정확하게 파악하기 위하여 다양한 배열 방법들이 요구되어 진다. 탐사 방법들은 험난한 산악지형에서 지형기복에 따른 장비와 인력의 이동에 대한 불편함을 줄이기 위하여 일정한 고도에서의 곡선적 측선에 대한 탐사, 시추공이 경사 곡선 수평적으로 되어 있을 경우 지표의 임의적 위치에서의 탐사, 여러 개의 전류원에 대하여 임의 위치에서 포텐셜을 측정하는 탐사 등으로 분류된다. 본 연구는 이러한 다양한 배열 방법으로 얻어진 복합적 자료들에 대하여 3차원 역산 방법을 사용하여 보다 신속하고 정확한 영상들로 나타내고자 한다. 또한 단층지역에서 곡선적 배열 방법으로 얻어진 측정 자료에 대한 3차원 역산 결과로부터 단층의 경사, 방향 및 폭 등에 관하여 정확한 전기비저항 영상들의 비교 결과도를 제시하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.87-92
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• 2007

This work describes the installation and preliminary measurements of an electrical resistivity tomography (ERT) system to monitor the injection of recycled water into a confined aquifer in the area of Sindos (Thessaloniki N. Greece). The aim is to provide, through time-lapse ERT measurements and processing, geoelectrical images of rather increased volumetric sampling around and between the holes and to obtain improved understanding of the flow and transport of the injected water. The details about the general setting, the construction and installation of the ERT cables into the boreholes are explained in full. Preliminary measurements involving single and cross-hole ERT measurements were obtained and processed with a 2D inversion algorithm to produce images of the subsurface. Results depict a very good correlation between ERT images and the lithology and resistivity logs; an indication of the reliability of the approach.

• Geomechanics and Engineering
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• 제24권1호
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• pp.1-14
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• 2021

In this study, a new approach using electrical resistivity measurement was proposed to detect grout penetration and to evaluate the grouting performance for such as waterproof efficiency in single rock fracture. For this purpose, an electrical resistivity monitoring system was designed to collect multi-channel data in real time. This was applied to a system for grout injection/penetration using a transparent fracture replica with various aperture sizes and water-cement mix ratio. The electrical resistivity was measured under various grout penetration conditions in real time, which results were directly compared to the visual observation images of grout penetration/distribution. Moreover, the grouting success status after the curing process was evaluated by measuring the electrical resistivity in relation to changes in frequency in fracture cells where grout injection and penetration were completed. Consequently, it was determined that the electrical resistivity monitoring system could be applied effectively to the detection of successful penetration of grouting into a target area and to actual field evaluation of the grouting performance and long-term stability of underground rock structures.

• 지구물리와물리탐사
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• 제1권1호
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• pp.57-63
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• 1998

전기비저항 탐사는 역사가 깊으며 널리 사용되는 물리탐사 기술 중의 하나로서 최근에는 단순한 이상대의 확인이 아닌 지하 구조를 영상화하는 것으로 확대, 발전되면서 토목 및 환경 분야에 많은 적용이 시도되고 있다. 본 연구에서는 환경 분야에서의 전기비저항 탐사의 응용 가능성을 입증하기 위하여 전주시 소재의 폐기물 처분장에서 10 m 간격의 쌍극자 배열 전기비저항 탐사를 8개의 측선상에서 수행하였다. 자동 측정 소프트웨어를 개발하여 자료를 획득하였으며 자료처리 과정에서 지형 효과를 보정하였다. 처분장 내부는 대단히 낮은 저비저항대가 발달하고 있으며 삼천천 쪽을 제외하고는 처분장 부지와 저비저항대의 분포가 정확하게 일치하였다. 또한 오염물질의 수직적인 분포도 삼천천 방향으로 가면서 그 심도가 계속적으로 깊어진다. 이는 삼천천 쪽을 제외하고는 처분장의 방벽이 오염물질의 확산을 잘 막아주고 있으며 오염물질이 삼천천 방향으로 확산되었을 가능성이 높다는 것을 의미한다. 전기비저항 영상화 기법을 이용하여 오염대의 수평/수직적인 분포, 심도별 오염물질의 발달 경향, 폐기물 처분의 최대 심도등의 유추가 가능하며 이는 환경 분야에서 전기비저항 탐사의 응용 가능성을 입증하는 것이다.

• 통합자연과학논문집
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• 제2권3호
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• pp.202-206
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• 2009

Optical images based on the porous silicon exhibiting photoluminescence have been prepared from an electrochemical etching of n-type silicon wafer (boron-doped,<100> orientation, resistivity $1{\sim}10{\Omega}-cm$) by using a beam projector. The images remained in the substrate displayed an optical images correlating to the optical pattern and could be useful for optical data storage. This provides the ability to fabricate complex optical encoding in the surface of silicon.

• 한국전기전자재료학회논문지
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• 제17권1호
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• pp.70-74
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• 2004

We investigated transmittance, surface characteristics, and resistivity according to bending of ITO(indium tin oxide) film with four other multi -harrier film). Transmission data of ITO film with four ITO films showed there was about large 90％ transmission above 550nm wavelength at three multi-barrier structures. But, both-side hard coated structure showed relatively low 75％ transmission above 550nm wavelength. And, surface images measured from SEM (scanning electron microscope) showed both-side hard coated structure have a tendency of more roughness. Also, resistivity change of four other multi-barrier film showed there was the lowest change at one-side hardcoated structure. Subsequently, with result of resistivity change according to position, we knew the resistivity change of the center increased rapidly than that of the edge.