• Economic and Environmental Geology
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• v.27 no.6
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• pp.563-569
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• 1994

Resistivity Image Profiling has been applied to a geological survey in the Keoje-do area. Survey lines are located near the KD-02 and KD-06 wells in the area, where we have already sampled all rock cores and carried out several kinds of geophysical logs. In each site a resistivity cross-section is obtained by inverting pole-pole apparent resistivities. Comparing the reconstructed resistivity section with the rock cores and logging data obtained in the well provides a detailed picture of subsurface geology. The geology of KD-02 site is composed of conglomerate, sandstone and shale with fractures. The reconstructed resistivity image is useful for assessing the grade of weathering of these rocks. The KD-06 site is mainly underlain by granitic rocks, and its fresh basement can be delineated by resistivities over $1000{\Omega}{\cdot}m$.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.271-277
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• 2007

To find out the anomalous zone in cut slope composed of phyllite and shist, we performed resistivity tomography using a pole-dipole way. The electrical distribution that propagates from a current source in lower part of slope is measured by a potential electrode in upper part of slope. Apparent resistivity data are inverted with an iterative regularized inversion method to reconstruct 3D resistivity image. By comparing with the resistivity images in relation to each section, the images of anomalous zone correspond to their positions represented in cut slope. Therefore, the application of resistivity tomography in cut slope is useful to recognize the extension of anomalous zone.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.353-359
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• 2012

The identification of effective root zone would clarify dynamics of plant available water and soil water balance. Using the relationship between soil properties and electrical resistivity (ER) the purpose of this research is to identify soil zone affected by a plant root activity using electrical resistivity tomography (ERT) technique. Four plastic containers were prepared for two different soil textures (clay and sandy loam) and one container for each texture was selected for planting four corn seedlings (Zea mays L.) and the others were prepared for the blank. For ERT monitoring, we prepared 0.8 m plastic sticks with 17 electrodes installed with 5 cm space. The Ministing (AGI Inc., Texas) instrument for electrical resistivity measurement and semi-auto converter of electrode arrangement were set up for dipole-dipole array. During 2 months of the corns growing, ERT monitoring was made 3 to 4 days after the irrigation practice. Despite of the same amount water supplied into soils, two textures showed very different apparent resistivity values due to different clay content. The apparent electrical resistivity is consistently lower in clay loam comparing to sandy loam soil implying that plant root does not significantly alter the overall trend of resistivity. When plant root system, however, is active both soils with plants showed 2-7 times higher electrical resistivity and higher coefficient variation than soils without plant, implying the effect of root system on the resistivity, in which may caused by. This result suggests plant root activities regulating the soil water dynamics mainly control the variation of electrical resistivity over soil textural difference. Therefore the identification of water uptake zone would highly be correlated to plant root activities, thus ERT will be feasible approach to identify spatial characteristics of a plant root activity.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.117-120
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• 2003

Electro-micromechanical techniques were applied using four-probe method for carbon nanotube (CNT) or nanofiber (CNF)/epoxy composites with their content. Carbon black (CB) was used to compare with CNT and CNF. The fracture of carbon fiber was detected by nondestructive acoustic emission (AE) relating to electrical resistivity for double-matrix composites test. Sensing for fiber tension was performed by electro-pullout test under uniform cyclic strain. The sensitivity for fiber damage such as fiber fracture and fiber tension was the highest for CNT/epoxy composites, and in CB case they were the lowest compared with CNT and CNF. Reinforcing effect of CNT obtained from apparent modulus measurement was the highest in the same content. The results obtained from sensing fiber damage were correlated with the morphological observation of nano-scale structure using FE-SEM. The information on fiber damage and matrix deformation and reinforcing effect of carbon nanocomposites could be obtained from electrical resistivity measurement as a new concept of nondestructive evaluation.

• Journal of Korean Society of societal Security
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• v.2 no.3
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• pp.39-46
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• 2009

A small loop-loop multi-frequency electromagnetic(EM) induction method is a useful technique to map a resistivity distribution efficiently and non-destructively. However, for quantitative interpretation and depth sounding, the quality of measured data is crucial. In this paper, we propose a bias correction of measured data by using background noise measurements to obtain reliable data, and propose an evaluation technique of apparent that can provide a resistivity image easily. We have performed small loop-loop EM measurements to detect water saturation in a man-made test site. The application of our proposed techniques to the measured data was successful.

• Economic and Environmental Geology
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• v.18 no.1
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• pp.41-47
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• 1985

The filtering ability of $J_0$ and $J_1$ digital linear filters is compared by means of an adaptive linear filter. Any $J_0$ domain Hankel transform integral can be transformed mathematically into its corresponding $J_1$ domain integral. The apparent resistivities for any electrode configuration employed in resistivity soundings can be evaluated with a single $J_1$ filter. The $J_1$ filter usually has similar accuracy to, but shorter length than, the corresponding $J_0$ filter. The domain transformation from $J_0$ to $J_1$ enables us to use effective expressions of apparent resistivity, involving $J_1$ alone, not only for Schlumberger but also for dipole-dipole array.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.251-256
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• 2007

The aim of this paper is development of resistivity seismic dilatometer (RSDMT) system. The resistivity module for obtaining apparent resistivity depth plot and seismic module for obtaining shear wave velocity (Vs) depth plot are attached to the conventional flat dilatometer testing equipment. From shear wave velocity profile, the stiffness at low strains of a site can be evaluated in undisturbed condition. And the resistivity value contains some information about water content and mineral characteristics of clayey soil. Specially manufactured resistivity and seismic modules were connected between commercialized DMT blade and drilling rod. To enhance reliability and repeatability of RSDMT test, automatic testing system including notebook based data acquisition system and automatic surface source system were developed. RSDMT system can be performed rapidly and can obtaine more reliable data at the same point compared with the separated testing system. The verification studies for the developed RSDMT system are going to be performed. From these studies, the effectiveness of integrated hybrid testing system will be checked in light of proper evaluation of geotechnical design parameters of clayey soils.

• Geophysics and Geophysical Exploration
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• v.18 no.1
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• pp.14-20
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• 2015

Three-dimensional (3D) resistivity method is an effective tool in the engineering site survey because it can provide a 3D resistivity distribution of the site. In this study, we tried to find out faults, fractures and coal seams that can cause the collapse of the tunnel. We carried out 2D resistivity survey along 5 parallel lines and 11 cross lines and merged all the apparent resistivity data for 3D inversion. Finally, from the 3D resistivity image and drilling data we presented the 3D distribution of faults, fractures and coal seams that are considered the main cause of the tunnel collapse.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.350-356
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• 2005

Earth equipments are essential to protect humans and other types of equipment from abnormal conditions. Earth resistance and potential must be restricted within a low value. An estimation algorithm of earth parameters and equivalent resistivity is introduced to calculate reliable earth resistance in this research. The proposed algorithm is based on the relationship between apparent resistances and earth parameters. The proposed algorithm, which approximates the non-linear characteristics of earth by using the Artificial Neural Network (ANN), estimates the earth parameters and equivalent resistivity. The effectiveness of the proposed method is verified with case studies.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.203-205
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• 1997

In this paper, we present a useful method of estimating earth resistivity using BP algorithm in Neural-Networks. From this method, equivalent earth resistivity(EER) can be obtained directly using training data composed of field-measured apparent resistivity and probe distance. This approach can reduce errors which is conventionally raised from manual operation of calculating EER. To evaluate its accuracy and convenience, the result of proposed method is compared to that of conventional methods, graphical($\rho$-a graph) and numerical(CDEGS program), respectively.