• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.732-737
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• 2012

This study made a specimen (contact surface size: $45\;mm{\times}0.02\;mm{\times}45{\sim}55\;mm$) with silicon rubber for low voltage cable with 50 phr silica filler. The electrification voltage of electrostatics were measured for different sizes of contact surface with the applied voltage of 10kV and the environmental settings of temperature ($25{\sim}40^{\circ}C$) and humidity (40~80%). The following conclusions were made. The electrification voltage of electrostatics decreased as the humidity increased. The electrification voltage of electrostatics increased as the temperature increased. The larger the surface size, the higher the electrification voltage of electrostatics. The property of the material had more effect on the relaxation time than the humidity.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.33-36
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• 2009

In this paper, evaluation of physical properties was made for dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of fatty acid monomolecular Arachidic Acid, Stearic Acid using compressing velocity. LB(Langmuir-Blodgett) thin films were manufacture by detecting deposition for the accumulation and the current was measured after the electric bias was applied across the manufactured MIM device. The physicochemical properties of the fatty acid monomolecular Arachidic Acid, Stearic Acid films surface structure has been studied by AFM. We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is gas state, liquid state, solid state. Formation that prevent when gas phase state and liquid phase state measure but could know organic matter that molecules form equal and stable film when molecules were not distributed evenly, and accumulated in solid state only.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1140-1149
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• 2004

The absorption characteristics of water vapor into a LiBr-H$_2$O solution flowing down on finned inclined surfaces are numerically investigated in order to study the absorbing performances of different surface shapes of finned tubes as an absorber element. A three-dimensional numerical model is developed. The momentum, energy, and diffusion equations are solved simultaneously using a finite difference method. In order to obtain the temperature and concentration distributions, the Runge-Kutta and the Successive over relaxation methods are used. The flat, circular, elliptic, and parabolic shapes of the tube surfaces are considered in order to find the optimal surface shapes for absorption. In addition, the effects of the fin intervals and Reynolds numbers are studied. The results show that the absorption mainly happens near the fin tip due to the temperature and concentration gradient, and the absorbing performance of the parabolic surface is better than those of the other surfaces.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.3 no.1
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• pp.18-25
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• 1978

The 1/f noise spectrum of short-circuited output drain current due to the Shockley-Read-Hal] recombination centers with a single lifetime in homogeneous nondegenerate MOS-field effcte transtors with n-type channel is calculated under the assumptions that the quasi-Fermi level for the carriers in each energy band can not be defined if we include the fluctuation for time varying quantities. and so 1/f noise is a majority carrier effect. Under these assumptions the derived 1/f noise in this paper show some essential features of the 1/f noise in MOS-field effect transistors. That is, it has no lowfrequency plateau and is proportionnal to the channel cross area A and to the driain bias voltage Vd and inversely proportional to the channel length L3 in MOS field effect transistors. This model can explain the discrepancy between the transition frequency of the noise spectrum from 1/f- response to 1/f2 and the frequency corresponding to the relaxation time related to the surface centers in p-n junction diodes. In this paper the results show that the functional form of noise spectrum is greatly influenced by the functional forms of the electron capture probability cn (E) and the relaxation time r (E) for scattering and the case of lattice scattering show to be responsible for the 4 noise in MOS fold effect transistors. So we canconclude that the source of 1/f noise is due to lattice scattering.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.464-472
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• 1996

The mechanism of thin-film formation by Ionized Cluster Beam Deposition(ICBD) was investigated. A simulation program based on the Monte-Carlo method was developed in order to investigate the effects of the acceleration voltage, substrate temperature, activation energy for the surface migration, and critical nuclei size on grain size and surface roughness. Studies of the effect of kinetic energy of clusters on the film formation processes revealed that high acceleration voltage enhanced the surface-migration of adatoms and made it easier for an epitaxial film to be formed. The relaxation time of kinetic energy of adatoms increased with the substrate temperature, which in turn increased the grain size of the crystalline film. This effect was more clearly distinguished when the critical nuclei size was large. The surface-migration activation energy was found to affect the interaction between the adatoms and the substrate and thus the relaxation time of kinetic energy. Investigations of the surface roughness revealed that the acceleration voltage, the substrate temperature, and the surface-migration activation energy exerted a collective effect on the morphology of the film surface.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.135-136
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• 2006

The shear flow properties have been reported in many cases by manufactures and fabricators. Only this characteristic is sometimes insufficient for the processings to provide a complete picture of the relationship between the processability and the flow behavior when underwent free-surface processes in which the shape and thickness of the extrudate are determined by the rheological properties of the melt, the die dimensions etc. In this paper the methodology of control of elongational flow is discussed in terms of relaxation time control of the polymer melts.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.565-572
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• 2009

This paper presents the optimization steps with weight and importance of estimated characteristic values in the multiresponse surface analysis(MRA). The research introduces the shape parameter of individual desirability function for relaxation and tighening of specification bounds. The study also proposes the combinded desirability function using arithmetic, geometric and harmonic means considering the measurement unit and numerical pattern.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.141.1-141
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• 1998

• Transactions of Materials Processing
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• v.13 no.7
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• pp.600-607
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• 2004

This paper addresses a viscoplastic constitutive model that allows a consistent way of modeling positive and negative rate sensitivities of flow stress concerned with dynamic strain aging. Based on the concept of continuum mechanics, a phenomenological constitutive model includes the use of a yield surface within the framework of unified viscoplasticity theory. To model negative rate sensitivity, rate-dependent back stress is introduced and flow stress in fully developed inelastic deformation regime is thus decomposed into the plastic contribution of rate independency and the viscous one of rate dependency.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1056-1062
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• 2008

The interaction between thrust plume and satellite base region was investigated by using direct simulate Monte-Carlo calculations. For the accurate simulation of N2 and H2 collisions and rotation-translation transition, a variable soft-sphere model and a recent rotational relaxation model of N2 and H2 were used. For the investigation of the interaction between thrust plume and base region, the number density distribution for each species, translational and rotational temperature distributions, heat flux, and pressure were examined by direct simulation of Monte-Carlo calculations. It was found that most of the surface properties are affected by H2 collisions and a strong non-equilibrium state is observed at the base region. It was demonstrated that an accurate model is needed to simulate H2 collisions and the rotation-translation transition. The results by the present calculation are more accurate than previous direct simulation Monte-Carlo calculations because more accurate rotational relaxation models were used in simulating the inelastic collisions.