• Computers and Concrete
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• v.12 no.3
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• pp.337-349
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• 2013

Traditional concrete is effectively an insulator in the dry state. However, conductive concrete can attain relatively high conductivity by adding a certain amount of electronically conductive components in the regular concrete matrix. The main purpose of this study is to investigate the electrical and thermal properties of conductive concrete with various graphite contents, specimen dimensions and applied voltages. For this purpose, six different mixtures (the control mixtures and five conductive mixtures with steel fibers of 2% by weight of coarse aggregate and graphite as fine aggregate replacement at the levels of 0%, 5%, 10%, 15% and 20% by weight) were prepared and concrete blocks with two types of dimensions were fabricated. Four test voltage levels, 48 V, 60 V, 110 V, and 220 V, were applied for the electrical and thermal tests. Test results show that the compressive strength of specimens decreases as the amount of graphite increases in concrete. The rising applied voltage decreases electrical resistivity and increases heat of concrete. Meanwhile, higher electrical current and temperature have been obtained in small size specimens than the comparable large size specimens. From the results, it can be concluded that the graphite contents, applied voltage levels, and the specimen dimensions play important roles in electrical and thermal properties of concrete. In addition, the superior electrical and thermal properties have been obtained in the mixture adding 2% steel fibers and 10% graphite.

• Polymer(Korea)
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• v.37 no.6
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• pp.722-729
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• 2013

In order to enhance the thermal conductivity of poly(dimethyl siloxane) (PDMS), boron nitride (BN) and carbon nanotubes (CNTs) were incorporated as the thermally conductive fillers. The amount of BN was increased from 0 to 100 phr (parts per hundred rubber) and the amount of CNTs was increased from 0 to 4 phr at a fixed amount of the boron nitride (100 phr). The thermal conductivity of the composites increased with an increasing concentration of BN, but the incorporation of CNTs had only a slight effect on the enhancement of thermal conductivity. Unexpectedly, the thermal degradation of the composites was accelerated by the addition of CNTs in 100 phr BN filled PDMS. Activation energy for thermal decomposition of the composites was calculated using the Horowitz-Metzger method. The curing behavior, electrical resistivity, and mechanical properties of PDMS filled with BN and CNTs were investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.1010-1017
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• 2011

The use of plated front contact for metallization of silicon solar cell may alternative technologies as a screen printed and silver paste contact. This technologies should allow the formation of contact with low contact resistivity a high line conductivity and also reduction of shading losses. A selective emitter structure with highly dopes regions underneath the metal contacts, is widely known to be one of the most promising high-efficiency solution in solar cell processing. When fabricated Ni/Cu plating metallization cell with a selective emitter structure, it has been shown that efficiencies of up to 18% have been achieved using this technology.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.1013-1020
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• 1992

The conductivity variation of a high resistivity bulk silicon semiconductor, whose electrodes were deposited with aluminum vapor, was studied experimentally by measuring the X-ray intensity and current flow, which was developed by X-ray radiation while applying a pulse voltage to the silicon, in a load resistor connected to the semiconductor. The current flow observed immediately as the X-ray radiated, and when the X-ray decreased. It was found from the observation of switching current for the X-ray intensity and the voltage applied in the semiconductor that the switching current of the semiconductor increased as the intensity of the X-ray and the applied voltage increased. In case of lower applied voltage, the switching current for higher applied voltage depended on the intensity of the X-ray radiated due to the saturation of electron and hole.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.995-1001
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• 1998

As a basic study for cathode materials of {{{{ { {LiMn }_{2 }O }_{4 } }}-based lithium-ion secondary batteries Li({{{{ { { { {Mn }_{1-$\delta$ }Nb }_{$\delta$} )}_{2 }O }_{4 } }} ($\delta$=0.05, 0.1, 0.2) materials which Nb is substituted for Mn were synthesized by the solid state reaction at 80$0^{\circ}C$ and 110$0^{\circ}C$ respectively. The second phase {{{{ { LiNbO}_{3 } }} appeared above $\delta$=0.1 As the result of im-pedance analysis as the amount of substituted Nb increased the resistivity of grain boundary increased greatly. Compared to undoped-{{{{ { {LiMn }_{2 }O }_{4 } }} the electrical conductivity of Li({{{{ { { { {Mn }_{1-$\delta$ }Nb }_{$\delta$} )}_{2 }O }_{4 } }} decreased slightly but is charging capacity and potential plateau increased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.590-594
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• 2012

ZnO nanowires were fabricated by hydrothermal synthesis technique for field emission device application. Al-doped zinc oxide (AZO) thin films were prepared as seed layer of catalyst for the ZnO nanowire synthesis, for which conductivity of the seed layer was tried to be improved for enhancing the field emission property of the ZnO nanowire. The AZO seed layer revealed specific resistivity of $ 7.466{\times}10^{-4}[{\Omega}{\cdot}cm]$ and carrier mobility of 18.6[$cm^2$/Vs]. Additionally, upper tip of the prepared ZnO nanowires was treated by hydrochloric acid (HCl) to form a nanocone shape of ZnO nanowire, which was aimed for enhanced focusing of electric field on that and resultingly to improve field emission property of the ZnO nanowires. The ZnO nanowire with nanocone shape revealed decreased threshold electric field and increased current density than those of the simple ZnO nanowires.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.223-226
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• 1998

Organic conducting N-methyl phenazinium TCNQ (7,7,8,8-tetracyanoquinonedimethane) ion radical salt was synthesized and characterized by FTIR, EA. After blending this material with PMMA using NMP/DMF, the solution was bar-coated on a PET film and dried at 40$^{\circ}C$. The optical micrograph showed the fibril crystals. The surface resistivity was 10$\^$5/ $\Omega$/$\square$. The conductivity decreased considerably at temperatures above 80$^{\circ}C$, although it decreased slightly at RT and 4$^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.134-136
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• 2004

The results of investigations of $Ag_2Te$ crystal is presented. $Ag_2Te$ crystal was grown by the Bridgman method. The $Ag_2Te$ crystal was an monoclinic structure with lattice constance a = 8.1686 A, b = 9.0425 ${{\AA}}$, c = 8.0065 ${{\AA}}$. Hall effect shows a n-type conductivity in the $Ag_2Te$ crystal. The electrical resistivity values was $1.080e^{-3}{\Omega}cm$ and electron mobility was $-5.48{\times}10^3cm^2/V{\cdot}sec$ at room temperature(RT).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.79-81
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• 1996

We fabricated SrTiO$_3$thin film capacitor on the Ag/Si-wafer by RF sputtering deposition. And I-V characteristics and structual analysis of the thin film capacitor are investigated. We found that the leakage current of the films during deposition is strongly denpent on the ambient gas and substrate temperature. Because of increase of activation energy, leakage current increased at high temperature and resistivity of the films was decreased. According to the increase of oxygen gas flow rate, the conductivity of thin film capacitor was increased and leakage current was decreased.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1407-1409
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• 2003

The results of investigations of $Ag_2Te$ crystal is presented. $Ag_2Te$ crystal was grown by the Bridgman method. The $Ag_2Te$ crystal was an monoclinic structure with lattice constance a = 8.1686, b=9.0425, c=8.0065. Hall effect shows a n-type conductivity in the $Ag_2Te$ crystal. The electrical resistivity values was $1.080e^{-3}cm$ and electron mobility was $-5.4810^{3}cm^{2}$/Vsec at room temperature(RT).