• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.99-104
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• 2003

TiN coated films show a good mechanical properties, high thermal properties and wear, erosion and corrosion resistance and are widely used as a coating materials in tools, ornaments, parts and semiconductors. In spite of these good properties, the fracture of TiN coated films occur during use. The fracture of TiN thin films is related to their microstructure. Especially, the life of TiN coated layer is related to the texture of the TiN films. One researcher suggested that the corrosion and erosion resistance of the TiN thin films is related to a uniform and dense structure of films. In this study, we studied the relationships between textures and friction coefficient, erosion and corrosion in TiN coated films. The flatness of (115) texture surface of TiN thin films is flatter than that of (111) texture surface. The friction coefficient of (115) texture surface of TiN thin films is similar with that of (111) texture surface. The wear resistance of (115) texture surface of TiN thin films is better than that of (111) texture surface. The erosion and corrosion resistance of (115) texture surface of TiN thin films is better than that of (111) torture surface. As well as texture, the wear, erosion and corrosion of TiN thin films has to consider defects such as pinholes, cracks, surface roughness and open columnar structure. The life of TiN coated products is influenced by the properties of wear, erosion, and corrosion resistance of TiN thin films and is related to texture of TiN coated films, density of pinholes and cracks, density of structure, and surface flatness.

• New & Renewable Energy
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• v.4 no.1
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• pp.31-36
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• 2008

Stainless steels have been widely considered as metallic bipolar plates, due to their passive surface film, which is good for corrosion resistance. However, the high resistivity of the passive film increases interfacial contact resistance between the bipolar plates and the electrodes. Stainless steels thermal spray coated with a mixture of tungsten carbide and stainless steel powders showed that the coated layer safely combined with the matrix but they suffered many internal defects including voids and cracks. Many cracks were formed in the coated layer and the interface of the matrix and the coated layer during the rolling process. The coated and rolled stainless steels showed lower interfacial contact resistance and corrosion resistance than bare stainless steel because of low resistivity of tungsten carbide and numerous defects, which caused crevice corrosion, in the coated layer.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2276-2283
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• 2018

A 50kW-4000rpm interior permanent magnet synchronous machine (IPMSM) applied to the high-performance electric vehicle (EV) is introduced in this paper. The main work of this paper is that a 2-D T-type lumped-parameter thermal network (LPTN) model is presented for IPMSM temperature rise calculation. Thermal conductance matrix equation is generated based on calculated thermal resistance and loss. Thus the temperature of each node is obtained by solving thermal conductance matrix. Then a 3-D liquid-solid coupling model is built to compare with the 2-D T-type LPTN model. Finally, an experimental platform is established to verify the above-mentioned methods, which obtains the measured efficiency map and current wave at rated load case and overload case. Thermocouple PTC100 is used to measure the temperature of the stator winding and iron core, and the FLUKE infrared-thermal-imager is applied to measure the surface temperature of IPMSM and controller. Test results show that the 2-D T-type LPTN model have a high accuracy to predict each part temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.136-142
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• 2008

Thermal management of a junction box of a passenger car has recently become more challenging due to its smaller size and larger current capacity. Thus, it is essential to perform the thermal optimization of a junction box in its design on an early stage of vehicle design. In this study, 3 dimensional CFD simulation with experimental measurement has been done to study for better thermal management of the junction box. First, the study of thermal characteristics of electric relays in the junction box has revealed that each surface of the relay has very different thermal resistance. In addition, an idea to install a cooling fan on the junction box has been studied and it was found that the forced cooling method was not effective on the system to keep the thermal resistance to the reasonable level of the junction box. Finally, the effect of external flows around the junction box on the temperatures of the relays, fuses, etc. has been studied and the result shows that the installation of the junction box at the proper place in an engine room can avoid any unnecessary overdesign in thermal management.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.343-344
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• 2008

A surface micromachined uncooled microbolometer based on the amorphous silicon was designed, fabricated, and characterized. We designed the microbolometer with a pixel size of $44\times44{\mu}m^2$ and a fill factor of about 50 % ~ 70% by considering such important factors as the thermal conductance, thermal time constant, the temperature coefficient of resistance, and device resistance. Also, we successfully fabricated the microbolometer by using surface MEMS technology. Finally, we investigated responsivity and detectivity properties depends on the active area size.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.77-83
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• 2004

In this study, the spray cooling heat transfer and working characteristics of the screen wick heat pipe with ultrasonic spray cooling system in condenser were experimentally investigated. The heat pipe was made of copper tube 300 mm long with inner diameter of 11.1 mm. The evaporator and condenser lengths of heat pipe were 40, 200 mm and the wick structure consists of two layer of 100 mesh copper screen. The experimental results show that the ultrasonic spray cooling increases the heat transfer rate on the condenser surface, and the total thermal resistance of heat pipe system decreases remarkably. A comparison is made for the two working fluids, water and ethanol. The surface temperature of the ethanol tube in evaporator section becomes higher than that of the water tube. Thus, the experimental result shows that water is more useful than ethanol as the working fluid because of increasing the operational limit within this experimental conditions.

• Journal of the Korean institute of surface engineering
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• v.31 no.1
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• pp.3-11
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• 1998

Molten Carbonate Fuel cell is a promising new type electric power generation system which can achieve high efficiency, lower matrrial cost and high operating temperature Making internal reforming possible. Although the development of the MCEC is progressing rapidly toward commercialization, two important tchological problems such as dissolution of NiO cathode and not corrosion of metallic separator plate must be resolved. Because MCFC is operated at $650^{\circ}C$ and the electrolyte is very corrosive, corrosion-resistance of separator plated against oxidation abd molten carbonate is required. Al-coating on separator material for corrosion-resistance was carried out by painting, thermal spraying. hot dipping and vacuum vapour deposition. The corrosion of Al-coated STS 316S and 316L in molten carbonate at $700^{\circ}C$was studied. Vacuum vapour deposition and thermal spraing for Al-coating on STS 310S and 316L were the most effective methods for protecting thestainless steel corrosion in molten carbonate.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.71-74
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• 2012

Uniformity of the wafer temperature is one of the important factors in etching process. Plasma, chucking force, backside helium pressure and the surface temperature of ESC(electrostatic chuck) affect the wafer temperature. ESC consists of several layers of structure. Each layer has own thermal resistance and the Si-adhesive layer has highest thermal resistance among them. In this work, the temperature distribution of ESC was analyzed by 3-D FEM with various defects and the thickness deviation of the Si-adhesive layer. The result with Si-adhesive layer with the low center thickness deviation shows modified temperature distribution of ESC surface.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.323-329
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• 2014

Effects of sealant and sealing procedure on corrosion resistance of high velocity oxy-fuel (HVOF) sprayed coatings were studied. HVOF-sprayed CrC-20NiCr coatings were sealed using three commercial sealants based on phenolics and epoxy. Penetration depth of sealants, measured by fluorescent microscope technique, was between $19{\mu}m$ and $340{\mu}m$ depending on sealant, sealing condition or sealing procedure. It was found that sealing on rotation status was more effective than that on stationary specimen due to the Coriolis effect of fluid in pores of the coating. From the CASS results, corrosion resistance of properly sealed CrC-20NiCr coatings was equal to that of hexa-valent chromium plating.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.528-534
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• 2011

In this paper, thermal characteristics of cylindrical grooved wick heat pipes with water-based MWCNT nanofluids as working medium are experimentally investigated. Volume fractions of nanoparticles are varied with 0.1% to 0.5%. Transient hot wire method developed in house is used to measure the thermal conductivity of nanofluids. It is enhanced by up to 29% compared to that of DI water. The thermal resistances and temperature distributions at the surface of the heat pipes are measured at the same evaporation temperature. The experimental results show that the thermal resistance of the heat pipes with water-based MWCNT nanofluids as working fluid is reduced up to 35.2% compared with that of heat pipe using DI water. The reduction rate of thermal resistance is greater than the enhancement rate of thermal conductivity. Finally, based on the experimental results, we present the reduction of the thermal resistances of the heat pipes compared with conventional heat pipes cannot be explained by only the thermal conductivity of water-based MWCNT nanofluids.