• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.582-586
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• 2005

We have grown GaN layers with in-situ SiN mask by metal organic chemical vapor deposition (MOCVD) and study the physical properties of the GaN layer. We have also investigate the effect of the SiN mask on its optical property. By inserting a SiN mask, (102) the full width at half maximum (FWHM) decreased from 480 arcsec to 409 arcsec and threading dislocation (TD) density decreased from $3.21\times10^9\;cm^{-2}\;to\;9.7\times10^8\;cm^{-2}$. The PL intensity of GaN with SiN mask improved 2 times to that without SiN mask. We have thus shown that the SiN mask improved significantly the physical and optical properties of the GaN layer.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1977-1979
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• 1999

This work characterized in terms of the physical properties of heavy elements as reduction filter in the diagnostic radiology. From the results of experimental evaluation, it was founded that in the case of the Ho filter, the variety of X-ray property with kVp was less than those of Ba, Cu and Al. And the ratio of transit-dose to surface and the load of X-ray tube were increased in the order of Al, Ba, Cu and Ho. The contrast of X-ray image showed the higher value in the order of Cu, Al, Ba and Ho.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.156-159
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• 2000

In this paper, the physical and electrical properties of epoxy composites are investigated at boiling absorption condition to observe the influences of moisture. Also, in order to improve water resistance of matrix resin, IPN method was introduced and the influence was investigated. In order to analyze the basic physical properties of samples, scanning electron microscopy method was utilized, and impulse voltage dielectric strength was measured. As a result, it was verified that, in case of IPN samples, the ratio of moisture absorption was decreased due to the improvement of adhesion strength, and impulse voltage dielectric strength of SN sample was degraded abruptly as boiling time and filler content were increasing, while IPN samples were slowly degraded due to the improvement of adhesion strength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.510-513
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• 2003

In this paper, we have investigated the physical, dielectric and electrical conduction properties of polyethylene terephthalate(PET) film due to temperature variation. From FT-IR spectrum as an analysis of physical properties, the strong absorption in wavenumber 1019[$cm^{-1}$], 1266[$cm^{-1}$], and 1752[$cm^{-1}$] observed by the C=O and benzene ring. the characteristics of volume resistivity used to highmegohm meter is measured from 1 to 10 minutes when the specimen applied the voltage according to the step voltage appling method. and dielectric characteristics were measured in the temperature range from room temperature to 120[$^{\circ}C$] due to frequency variation.. also we measured in the voltage rang of 1[V] to 20[V] according to the voltage application method.

• Journal of Information Display
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• v.13 no.4
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• pp.145-149
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• 2012

Liquid crystals are useful for a wide range of applications due to their exceptional properties. Doping of liquid crystals with carbon nanotubes (CNTs), even at very low concentrations, produces a detectable effect on the liquid crystal (LC) properties that can be very attractive for various functions. In this study, an attempt was made to investigate the effect of CNTs on the electrical properties of a short-pitch and high-spontaneous-polarization ferro-electric LC mixture, FLC-6304, at different temperatures. The inclusion of the CNTs significantly reduced the polarization at temperatures well within the $SmC^*$ phase, but the effect was gradually reversed as the transition temperature was approached. The insertion of the CNTs also reduced the response time and the rotational viscosity of the FLC mixture, which is highly desirable in the LCD industry.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1126-1128
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• 1995

In order to investigate the electrical properties for transformer oils due to electron bean irradition, the dielectric properties was made researches by dose of irradition To measure the dielectric loss of irradiated specimen, coaxial cylindrical liquid electrode was used, geometric capacitance was confirmed to 16[pF]. Experiments for measuring the dielectric loss were performed at $20{\sim}120[^{\circ}C]$ in temperature range, $30{\sim}1.5{\times}10^5$[Hz] in frequency range and $300{\sim}1500$[mV] in voltage range and then, the result of experiment for the movement of carrier and the physical constants to contribute dielectric properties of specimen due to electron beam irradiation introduced.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1556-1558
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• 1996

In order to investigate the electrical properties for transformer oils which contains a pure sodium chloride, the dielectric properties is made researches. This experiments for measuring the dielectric loss is performed at $20{\sim}120[^{\circ}C]$ in the temperature range, $30{\sim}1.5{\times}10^5[Hz}$ in the frequency range and $300{\sim}1500[mV]$ in the voltage range. The result of experiment for the movement of carrier and the physical constants to contribute dielectric properties of specimen with a pure sodium chloride.

• Polymer(Korea)
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• v.37 no.4
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• pp.526-532
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• 2013

The effect of CNT dispersion method on rheological and electrical properties of polystyrene/carbon nanotube (PS/CNT) nanocomposites via latex technology was compared. The nanocomposites were prepared through freeze-drying the dispersed suspension comprised of CNTs and PS particles. In this study, physical dispersion method, either sodium dodecylsulfate (SDS) addition or polyvinyl pyrrolidone (PVP) wrapping, was employed to prevent the deterioration of intrinsic properties of CNT caused by chemical modification. The physical method applied to latex technology was very effective in CNT dispersion. With SDS addition, the enhancement of rheological properties was low compared to PVP wrapping because the properties of matrix were deteriorated due to the incorporation of low molecular weight SDS. The electrical percolation threshold of PS/SDS-stabilized CNT and PS/PVP-wrapped CNT nanocomposites was 0.23 and 0.90 wt%, respectively. The enhancement of electrical conductivity was low in the case of PVP wrapping because the non-conducting PVPs wrapped around CNT restricted the electrical connection between CNTs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1633-1640
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• 2018

Epoxy resin is a polar thermosetting polymer that is widely employed in different branches of industry and everyday life, due to their stable physical and chemical properties. Of all the polymer materials currently being used in the electrical insulation industry, epoxy resin is the most widely used kind, chosen as the base polymer material in the present study. Composites were prepared according to the mixing ratio (MS: MA, 1: 9, 3: 7, 5: 5, 7: 3, 9: 1)of mixture for Heterogeneous Minerals(Micro Silica:MS, Micro Alumina:MA) (MS+MA). We have investigated for AC electrical insulation breakdown characteristics and the dielectric properties (permittivity, dielectric loss, and conductivity) with frequency changes. The electrical AC insulation breakdown performance was improved with the increase of the mixing ratio of MS according to heterogeneous mineral material mixture(MS+MA). As Dielectric properties, the dielectric constant and dielectric loss increased with decreasing frequency and decreased with increasing MS content ratio of heterogeneous mineral mixture. Tensile strength and flexural strength according to the mixing ratio (MS + MA) of epoxy / heterogeneous mineral mixture were studied by mechanical properties. The performance of mechanical tensile and flexural strength was significantly improved as the fill contents ratio of MS increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05c
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• pp.37-41
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• 2004

In this paper, evaluation of physical properties about dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DLPC, DMPC using pressure stimulus. As a result, the changed surface pressure, displacement current and the transition forms of dipole moment of phospolipid monomolecular in area per molecular by pressure stimulus were conformed well. It was known that the monolayers by linear relationship for decision of dielectric relaxation time between compressure speed and molecule area By according to the linear relationship relation get that frictional constant, DLPC was $1.89{\times}10^{-19}$ [Js] and DMPC was $0.722{\times}10^{-19}$[Js]. lt is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area.