• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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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.

• Korean Journal of Materials Research
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• v.18 no.5
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• pp.283-288
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• 2008

The effect of sintering aids and glass-frit on the densification and resistivity of silver paste was investigated in an effort to enhance the sintered density and electrical conductivity of the silver electrode. To prepare Pb-free silver paste for use at low sintering temperatures, two commercial silver powders ($0.8\;{\mu}m$ and $1.6\;{\mu}m$ in size) and 5wt.% lab-synthesized nanoparticles (30-50 nm in size) as a sintering aids were mixed with 3 wt.% or 6 wt.% of glass frit ($Bi_2O_3$-based) using a solvent and three roll mills. Thick films from the silver paste were prepared by means of screen printing on an alumina substrate followed by sintering at $450^{\circ}C$ to $550^{\circ}C$ for 15 min. Silver thick films from the paste with bimodal particles showed a high packing density, high densification during sintering and low resistivity compared to films created using monomodal particles. Silver nanoparticles as a sintering aid enhanced the densification of commercial silver powder at a low sintering temperature and induced low resistivity in the silver thick film. The glass frit also enhanced the densification of the films through liquid phase sintering; however, the optimum content of glass frit is necessary to ensure that a dense microstructure and low resistivity are obtained, as excessive glass-frit can provoke low conductivity due to the interconnection of the glass phase with the high resistivity between the silver particles.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.262-265
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• 2004

The purpose of this study is to investigate environmental characteristics and in-situ hydraulic conductivity by eco cone penetration system. The underground environments and permeability of site was investigated and analyzed by this eco cone system. The electrical resistivity, pH, ORP, temperature and hydraulic conductivity were measured by eco cone penetration system. This eco cone penetration system provides a continuous environment and permeability profiles in underground, and provides reliable results for investigation of normal and contaminated ground.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.316-316
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• 2014

Two different transparent conducting oxide (TCO) layers of Al-doped ZnO (AZO) and $WO_3$ were prepared by a rf sputtering process. Working pressure, deposition time, and target-to-substrate distance were varied for the sputtering process to improve electrical properties of the resulting layer. Thickness of the TCO layers was measured by a profile meter of ${\alpha}$-step. To evaluate the electrical conductivity, surface resistivity of the TCO layers was measured by a four-point probe technique. Decrease of the working pressure resulted in increase of deposition rate and decrease of surface resistivity of the resulting layer. Increase of the layer thickness due to increased deposition time resulted in decrease of surface resistivity of the resulting layer. The shorter the target-to-substrate distance was, the lower was the surface resistivity of the resulting layer.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1336-1338
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• 1997

Relations between the composites of SiC-$ZrB_2$ electro-conductive ceramic composites and their electrical resistivity, as well as their temperature, were investigated. The electrical resistivity of hot-pressed composites was measured by the Pauw method in the temperature of RT to $100^{\circ}C$. The electrical resistivity of the composites follow the electrical conduction model for a homogenous mixture of two kinds of particles with different conductivity. Also the electrical resistivity versus temperature curves indicate the formation of local chains of $ZrB_2$ particles. In the case of SiC-$ZrB_2$ composites containing above 30Vol.% $ZrB_2$ showed PTCR, whereas the electrical resistivity of SiC-15Vol.% $ZrB_2$ showed NTCR.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.4
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• pp.157-160
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• 2007

The van der Pauw technique is one of the popular methods for determining the conductivity of flat metal samples. Traceability of the national standard for the conductivity has been achieved by direct current measurement techniques in national measurement institutes of many countries. But recently, alternative current measurement techniques for determining the conductivity of flat metal samples is also interested. In this study, we measured the conductivity of non-ferrous and ferrous flat metals at alternative current using van der Pauw technique. As measurement results, the conductivities of the samples were decreased according to increasing the test frequency even though the decreasing ratio was different.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.432-435
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• 2006

To evaluate geology and extent of leachate migration around the landfills, electrical resistivity survey were conducted in area of uncontrolled landfills in Cheonan and Wonju. The Cheonan landfill is located above the paddy fields and the resistivity survey lines were crossed to confirm possible pollution of the paddy fields by leakage of the landfill leachate. In Wonju, the landfill and the downgradient paddy fields are divided by a concrete barrier wall. At the bottom of the landfill, there is a leachate settlement system but has not been in operation. And a total of 4 survey line installed (1 parallel and 3 perpendicular to mean groundwater flow direction). According to the resistivity survey results, the landfill leachate in Cheonan appeared to be restricted only within the interior of the landfill, not to migrate into the subsurface of the paddy fields. These results are well consistent with electrical conductivity values of groundwaters obtained from a periodic analysis of water qualities. In Wonju, however, it was inferred that the leachate emanating from the landfill migrated beneath the abandoned leachate settlement system and it would reach the downgradient paddy field.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.385-390
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• 1996

The electrical resistivity of the ceramic glaze coated on ceramic substrate plays an important role on the characteristics of the thick and thin film electrical circuits. In this study the effects of the various modifiers on the electrical resistivity were examined in SiO2-Al2O3-B2O3-RO-Na2O (RO=CaO , SrO, BaO, PbO) glass system. In alkali free glasses where divalent cations are responsible for electrical conduction the electrical conductivity of th glasses increased with the ionic size of divalent cations due to the decrease in the bond strength between oxyben and divalent cation. In Na2O containing glasses however where Na+ ion is responsible for electrical conduction the ionic conductivity decreased with the ionic size of divalent cations because the blocking effect of the cations on Na+ ion movement increased with larger divalent cations. Na+ ionic conduction also depended on the glass structure relaxation due to the corrdination number changes of B2O3 and Al2O3 which varied with the NaO2 content in the glass.

• Geophysics and Geophysical Exploration
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• v.7 no.3
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• pp.184-190
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• 2004

To analyze soil properties of unsaturated zone, we applied electrical resistivity tomography(ERT) of high resolution image. From linear relationship with each soil texture between results of ERT and soil properties such as electrical conductivity of pore water, water contents and ionic contents, we could be analyzed the result of ERT more effectively. Consequently, ERT can be useful for estimating soil properties between the two holes and evaluating indirectly pH and organic contents of soil.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.186-187
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• 2008

Electrical resistivity in hydrate-bearing sediments is sensitive to porosity, gas hydrate saturation, gas content, pore fluid composition, and temperature, so electrical measurements such as well logs and electromagnetic surveys have been used to explore gas hydrate-bearing formation. The high pressure tomography cell is designed considering the effect of electrode configuration and electrical shielding on tomography measurements and the safety. The evolution of electrical conductivity during $CO_2$ hydrate formation and dissociation reflects the combined effects of concurrent changes that include ionization of dissolved $CO_2$, temperature-dependent ionic mobility, changes in the degree of saturation, ion exclusion, surface conduction, and porosity changes. Measurements during hydrate formation and dissociation require careful analysis to properly interpret signatures, in particular when out-of plane conductivity anomalies prevail.