• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1473-1475
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• 2002

This study presents the dielectric properties of $Ta_2O_5$ MIM capacitor structure processed by thermal oxidation. The AES(auger electron emission) depth profile showed thermal oxidation effect gives rise to the $O_2$ deficiened into the new layer. The leakage current density respectively, at $1{\sim}3{\times}10^{-3}$(kV/cm) were $3{\times}10^{-4}-10^{-8}(A/cm^2)$. Leakage current density behavior is stable irrespective of applied electric field, the frequency va capacitance characteristic enhanced stability. The capacitance vs voltage measurement that, $V_{fb}$(flat-band voltage) was increase dependance on the thin films thickness, it is changed negative to positive.

• Journal of Power System Engineering
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• v.8 no.4
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• pp.38-43
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• 2004

Thermal spraying onto the metal substrate has been widely used as a technique of the surface treatment in the various industrial field. A wide range of thermal spray technologies exist and all rely on the fundamental process of fusing a metal feedstock, atomizing it and transporting it to the surface of a substrate. Specially, these methods have been taken into account as the protection method against the corrosion. In this study, the polarization characteristics were carried out on the thermal sprayed coating layer immersed in various pH of diluted aqueous solutions at $25^{\circ}C$. Aluminum, Zinc, Ni-base alloy, alumina and polyethylene powder were used with sprayed coating materials. From the polarization curves, the electrochemical corrosion potential($E_{corr}$) and the corrosion current density($I_{corr}$) were investigated.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.199-202
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• 2007

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean observation and meteorological observation. Conventional thermal control design, using MLI (Multi Layer Insulation), OSR (Optical Solar Reflector), heater and heat pipe, is utilized. Ka-band components are installed on South wall, while other equipment for sensors are installed on the opposite side, North wall. High dissipating communication units are located on external (surface) heat pipe and are covered by internal insulation blankets to decouple them from the rest of the satellite. External satellite walls are covered by MLI or OSR for insulation from space and for rejection internal heat to space. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. Single solar array wing is adopted in order to secure clear field of view of radiant cooler of IR meteorological sensor. This paper presents principles of thermal control design for the COMS.

• Tribology and Lubricants
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• v.11 no.5
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• pp.172-176
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• 1995

This study deals with thermomechanical cracking between the friction surface and the interior of the brake disc. Analytical model considered in this study was a semi-infinite solid subjected to the thermal loading of an asperity moving with a high speed. The temperature field and the thermal stress state were obtained and discussed on the basis of Von Mises and Tresca Yielding Criterion. Analytical results showed that the dominant stress in cracking of friction brake is thermal stress and cracking location is dependent on the friction coefficient of contact and Peclet number. On the basis of analytical results thermomechanical cracking model is proposed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.388-394
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• 2009

Precision positioning system with magnetostrictive actuator(MA) has widely used in manufacturing devices to control the positioning accuracy to meet the high load and stroke requirements. It has many advantage in comparison with piezoelectic actuator; high force, high strain, high efficient etc. But, the performance of Terfenol-D, the commercially available magnetostrictive material, is highly dependent on the prestress, magnetic field intensity and temperature. Therefore, thermal strain of magnetostrictive material obstructs precision position control of magnetostrictive actuator, magnetostrictive actuator is need of cooling system. In this paper, cooling system using compressed cold air is developed and proper temperature and velocity of compressed cold air is studied by thermal analysis according to applied current.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.83-89
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• 2011

Poly(vinyl alcohol) (PVA), PVA/Montmorillonite (MMT), PVA/Silver (Ag), and PVA/MMT/Ag nanocomposite nanowebs were prepared by electrospinning technique in aqueous solution. In order to investigate the effect of inorganic materials on the morphology and thermal properties of PVA based nanocomposite nanowebs, experiments were performed with 5 wt.% of MMT and Ag. Field emission type scanning electron microscopy, transmission electron microscopy (TEM), reflection type X-ray diffraction (XRD), and thermal gravimetric analyzer were utilized to characterize nanocomposite nanowebs. TEM and XRD results show MMT and Ag were well dispersed in PVA nanowebs. Those inorganic nanoparticles enhanced thermal property of the nanocomposite nanowebs.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.309-332
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• 2016

Finite element method has been applied to solve the fundamental governing equations of natural convective, electrically conducting, incompressible fluid flow past an infinite vertical plate surrounded by porous medium in presence of thermal radiation, viscous dissipation, Soret and Dufour effects. In this research work, the results of coupled partial differential equations are found numerically by applying finite element technique. The sway of significant parameters such as Soret number, Dufour number, Grashof number for heat and mass transfer, Magnetic field parameter, Thermal radiation parameter, Permeability parameter on velocity, temperature and concentration evaluations in the boundary layer region are examined in detail and the results are shown in graphically. Furthermore, the effect of these parameters on local skin friction coefficient, local Nusselt number and Sherwood numbers is also investigated. A very good agreement is noticed between the present results and previous published works in some limiting cases.

• International Journal of Fluid Machinery and Systems
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• v.2 no.2
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• pp.121-126
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• 2009

The internal flow field in a centrifugal pump working at the several flow conditions has been measured by using the particle image velocimetry (PIV) technique with the laser induced fluorescence (LIF) particles and the refractive index matched (RIM) facilities. The impeller of the centrifugal pump has an outlet diameter in 100mm, and consists of six two-dimensional curvature backward swept blades of constant thickness. Measured results give reliable flow patterns in the pump. It is obvious that application of LIF particle and RIM are the key methods to obtain the right PIV measured results in pump internal flow.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1188-1194
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• 2008

To cope with the demagnetization risk of permanent magnets used in Interior Permanent Magnet Synchronous Motors(IPMSM), an accurate iron analysis and thermal analysis are very important. In this research, to calculate thermal increment of IPMSM for high-speed traction motor, we will extract losses of IPMSM considering the condition of field weakening control. Then we will input the calculated losses such as iron loss and copper loss as the thermal sources. Based on magnetic filed and thermal analysis, we will support the design of IPMSM for high-speed train.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.159-166
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• 1998

To study temperature effect of P.C. box girder bridge, field measurement was performed for six months, along with thermal analysis for the newly constructed viaduct of Gangbyun Highway in Seoul. Thermocouples were installed inside and surface of the flange and web of the box and temperature of box section md ambient temperature was measured. Measured environmental data are incorporated in finite element thermal analysis and computed temperature of the section was compared with measured one. Temperature gradient from thermal analysis was compared with Korean Highway Specification(1996)and the New Zealand Ministry of Works and Development code(1976). Thermal stress distribution across the box section was also compared.