• 지구물리와물리탐사
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• 제10권4호
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• pp.361-368
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• 2007

본 논문은 지표 및 시추공 전기 전자탐사 결과의 정량적인 해석을 위하여 해안 지하수의 전기비저항과 등가 NaCl 염분도와의 관계식을 제안하였다. 해안에서 10 km 이내에 위치하고 전기전도도가 1,000 ${\mu}S/cm$ 이상인 38개의 지하수 시료에 대한 수리지구화학 분석 결과를 이용하여 전기비저항과 등가 NaCl 염분도와의 관계식을 유도하였다. 수리지구 화학분석 결과의 등가 NaCl 염분도 환산은 Schlumberger 도표 GEN-8을 이용하였으며 전기전도도는 현장에서 휴대용 장비로 측정하였다. 본 논문에서 해안 지하수의 수리지구화학분석 결과를 이용하여 제안한 해안 지하수의 전기비저항$(R_w)$ 과 등가 NaCl 염분도(Eq_NaCl)와의 관계식은 Eq_NaCl=$5935.3551{\times}R_w^{-1.0993}$이며 전기전도도(EC)와 용존고형물총량(TDS)과의 관계식은 TDS=0.721${times}$EC와 같다. 해안대수층 지하수의 전기비저항과 등가 NaCl 염분도 및 TDS와의 관계식은 서 남해 해안지역의 해수침투 평가에 유용하게 이용될 것으로 판단된다.

• 한국재료학회지
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• 제31권2호
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• pp.108-114
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• 2021

In the manufacturing of bulk graphite, pores produced by vaporization and discharge of volatile materials in binders during carbonization reduce the density of bulk graphite, which adversely affects the electrical conductivity, strength and mechanical properties. Therefore, an impregnation process is introduced to fill the pores and increase the density of bulk graphite. In this study, bulk graphite is prepared by varying the viscosity of the impregnant. The microstructure of bulk graphite is observed. The flexural strength and electrical resistivity are measured. As the viscosity of the impregnants decreases and the number of impregnations increases, it is shown that the number of pores decreases. The density before impregnation is 1.62 g/㎤. The density increases to 1.67 g/㎤ and porosity decreases by 18.6 % after three impregnations using 5.1 cP impregnant, resulting in the best pore-filling effect. After three times of impregnation with a viscosity of 5.1 cP, the flexural strength increases by 55.2 % and the electrical resistivity decreases by 86.76 %. This shows that a slight increase in density due to the pore-filling effect improves the properties of bulk graphite.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.136-141
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• 2000

Concrete has been used for many years as a composite material that has excellent mechanical properties and durability for construction. However, concrete ia a poor electrical conductor, especially under dry conditions. Concrete that is excellent in both mechanical and electrical conductivity properties may have important applications in the electrical, electronic, military and construction industry (e.g for de-icing road from snow). The purpose of this investigation is to improve the electrical conductive of cement mortar preparared with graphite as filler. From the test result, as the ratio of graphite/cement increased, fluidity, fluidity and strength decreased but resistivity decreased. The resistivity of electrical conductive cement mortar is effect by water/cement ratio and water content of specimen. From this study, it is enough to assure the use of graphite as a conductive filler for electrical conducive cement mortar.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.933-938
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• 2000

Concrete has been used for many years as a composite material that has excellent mechanical properties and durability for construction. However, concrete is a poor electrical conductor, especially under dry conditions. Concrete that is excellent in both mechanical and electrical conductivity properties may have important applications in the electrical, electronic, military and construction industry(e.g. for de-icing road from snow). The purpose of this investigation is to improve the electrical conductive of cement mortar preparared with coke dust, graphite, carbon black and carbon fiber as filler. From the test result, as the content of electrically conductive material increased, fluidity and strength decreased but resistivity decreased. The resistivity of electrical conductive cement mortar is effect by water/cement, and aggregate. Cement mortar containing carbon fiber has the best electrical properties considering strength. From this study, it is enough to assure the use of carbon fiber, carbon black and graphite as a conductive filler for electrical conductive cement mortar.

• 한국세라믹학회지
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• 제55권5호
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• pp.440-445
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• 2018

To control the electrical properties of a SiC heating element, we sintered $SiC-ZrB_2$composites by using the spark plasma sintering method. The addition of $ZrB_2$ particles with lower electrical conductivity to the SiC matrices with comparatively higher electrical resistivity lowers the electrical resistivities of the composite material. The $ZrB_2$ particles aggregate to form large particles and 3-1, 3-2, and 3-3 networks, i.e., conduction paths. In our study, about $1-{\mu}m$-sized $ZrB_2$ powders start to form the conduction path at about 10 vol.% of addition, namely the threshold volume. The Joule heating experiment shows that 20 vol.% $ZrB_2$-added SiC heating element has outstanding heating efficiency.

• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.367-373
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• 2007

[ $In_2O_3-ZnO(IZO)$ ] and $In_2O_3-ZnO-SnO_2(IZTO)$ thin films were prepared on EAGLE 2000 glass webs in a Ar gas by RF-Magnetron sputtering. Electrical resistivity and optical transmittance of the films were investigated. IZO, IZTO film showed excellent optical transmittance of 85 % at the visible $400{\sim}$780 nm wavelength. Electrical properties of IZO film have $6.50{\times}10^{-4}{\Omega}cm$ (95 $In_2O_3$ : 5 ZnO wt.%) and $5.20{\times}10^{-4}{\Omega}cm$ (90 : 10 wt.%), IZTO film have $8.00{\times}10^{-4}{\Omega}cm$ (90 $In_2O_3$ : 3 ZnO : 7 $SnO_2$ wt.%) and $6.50{\times}10^{-4}{\Omega}cm$ (90 : 7 : 3 wt.%). Substitution of SnO to ZnO in ITO films showed slightly lower electrical conductivity than ITO film but showed similar optical transmittance.

• Carbon letters
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• 제8권4호
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• pp.326-334
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• 2007

In this study, graphite composites were fabricated by warm press molding method to realize commercialization of PEM fuel cells. Graphite composites have been considered as alternative economic materials for bipolar plate of PEM fuel cells. Graphite powder that enables to provide electrical conductivity was selected as the main substance. The graphite powder was mixed with phenolic resin and the mixture was pressed using a warm press method. First of all, the graphite powder was pulverized with a ball mill for the dense packing of composite. As the ball milling time increases, the average size of particles decreases and the size distribution becomes narrow. This allows for improvement of the uniformity of graphite composite. However, the surface electrical resistivity of graphite composite increases as the ball milling time increases. It is due to that graphite particles with amorphous phase are generated on the surface due to the friction and collision of particles during pulverizing. We found that the contact electrical resistivity of graphite particles increases as the particle size decreases. The contact electrical resistivity of graphite powders was reduced due to high molding pressure by warm press molding. This leads to improvement of the mechanical properties of graphite composite. Hydrogen gas impermeability was measured with the graphite composite, showing a possibility of the application for bipolar plate in fuel cell. And, I-V curves of the graphite composite bipolar plate exhibit a similar performance to the graphite bipolar plate.

• 마이크로전자및패키징학회지
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• 제19권2호
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• pp.73-78
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• 2012

The chemical, electrical, and optical properties of ZnO and Al-doped ZnO films after high temperature annealing were studied. The resistivity increased significantly after annealing at $600^{\circ}C$ under $10^{-10}$ Torr atmosphere. The mechanism of the resistivity change was explored using photoemission spectroscopy and photoluminescence spectrometer. The results indicated that the amount of oxygen deficient region O-Zn bonds decreased and oxygen vacancy was decreased after the high temperature vacuum annealing. The increase in the resistivity of ZnO and Al-doped ZnO films was resulted from the decrease in carrier concentration due to a decrease in the amount of oxygen deficiency.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.448-453
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• 2006

Electrical resistivity is an important property for the collection efficiency in the electrostatic precipitator. In this paper, electrical resistivities of tobacco dusts, yellow sand dusts and pine pollens are measured using a high voltage conductivity cell based on JIS B 9915. The resistivities of three kinds of indoor dusts are about $1{\times}10^7\;{\Omega}{\cdot}cm^2$ in the normal range and dust collection efficiency using an electrostatic precipitator at to face velocity of 1.0 m/s shows over 99% for the three kinds of indoor dusts.

• 한국재료학회지
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• 제15권4호
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• pp.217-223
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• 2005

Thermal, electrical and mechanical properties of high purity niobium and tantalum refractory rare metals were investigated tn evaluate the physical purity. Higher purity niobium and tantalum metals showed lower hardness due to smaller solution hardening effect. Temperature dependence of electrical resistivity showed a typical metallic behavior. Remarkable decrease in electrical resistivity was observed for a high purity specimen at low temperature. However, thermal conductivity increased for a high purity specimen, and abrupt increase in thermal conductivity was observed at very low temperature, indicating typical temperature dependence of thermal conductivity for high purity metals. It can be known that reduction of electron-phonon scattering leads to increase in thermal conductivity of high purity niobium and tantalum metals at low temperature.