• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.911-918
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• 2002

The tribological performance of A1$_2$O$_3$/NiCr coating deposited on steel (SH45C) was investigated under lubrication. The parameters of sliding wear consist of normal load and coating thickness. Test result showed that there was no evidence of an improved bonding strength in the coating. However, the wear resistance of the A1$_2$O$_3$/NiCr coaling was significantly greater than that of the Al$_2$O$_3$ coating. It was eviclent that the residual stress for the A1$_2$O$_3$coating was higher than that of the A1$_2$O$_3$/NiCr coating from the Scratch test failure of coating. The bond coating played an important role in decreasing the residual stress. Also, it was found that the residual stress had d notable influence on the wear mechanism.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.124-128
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• 2004

By the use of a similar numerical method as that in the previous paper, the forming limit strain by coaling method of clad sheet metals is investigated, in which the FEM is applied and J2G(J$_2$-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Declined Multilayer Metals Materials are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.

• Journal of Industrial Technology
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• v.12
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• pp.51-59
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• 1992

In this paper, the technique to fabricate the optical fiber preforms by centrifuge was investigated, using silica particles of different sizes. The injection tube was designed to traverse axially so that uniform coaling of tiny silica particles onto the substrate tube can be certified. The deposition efficiencies and deposition rates of $SiO_2$ particles were measured to elucidate the effects of process variables such as rotation speed of rotor, aqueous flow rate, suspension concentration, binder concentration and overflow weir diameter. This study shows dearly the merit of this technique by enhancing abruptly the deposition rates and deposition efficiencies, comparing to the conventional processes for optical fiber preforms.

• Journal of Magnetics
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• v.6 no.1
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• pp.1-4
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• 2001

We have used acetic acids ethanol and distilled water as a solvent to synthesize $La_{2/3}Sr_{1/3}Mn_{0.99}{^{57}}Fe_{0.01}O_3$(LSMFO) precursor. Crack-free LSMFO granular polycrystalline thin films have been deposited on thermally oxidized silicon substrates by spin coaling. The dependence of crystallization, surface morphology, magnetic and transport properties on annealing temperature was investigated. With increasing annealing temperature, the metal-semiconductor (insulator) transition temperature and the magnetic moment decrease while the resistivity increases. The lattice constants remain almost unchanged. For LSMFO thin films, spin-dependent interfacial tunneling and/or scattering magnetoresistance were observed. Our results indicate that the annealing temperature is very important in determining the intrinsic and extrinsic magnetotransport properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.35-37
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• 1988

Polycrystalline $Cd_{1-x}Zn_xS$ films were prepared by coaling a slurry which consisted of CdS, ZnS, $CdCl_2$ and propylene glycol on gloss substrates and by sintering in a nitrogen atmosphere. Microstructures, optical transmittance and electrical resistance of the sintered films have been investigatd. Grain shape of $Cd_{1-x}Zn_xS$ films sintered in a sealed boat was nearly spherical but the shape became, irregular when sintered in evaporating condition due to occurrence of CIGM (Chemically Induced Grain-boundary Migration). Controlling the rate of evaporation of $CdCl_2$, sintered $Cd_{1-x}Zn_xS$ films with high optical transmittance and low electrical resistance could be obtained.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.777-782
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• 1998

To terminate the progression of the sever accident and mitigate the accident consequences, corium coaling has been suggested as one of most important design features considered in the swore accident mitigation. Till now, some kinds of cooling methodologies have been identified and, specially the corium cooling at the reactor cavity has been considered as one of the most promising cooling methodologies. Moreover, several design requirements related to the cerium cooling at the reactor cavity have been also suggested and applied to the design of the next generation reactor. In this study technical description are briefly described for the important issues related to the cerium cooling at the reactor cavity, i.e. cavity area, cavity flooding system, etc., and simple evaluation for those items have been performed considering present technical levels the experiment and analytical works..

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.109-112
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• 1999

The PZT(10/90)/(90/17) heterolayered thin films were fabricated by the spin-coaling on the Pt/Ti/SiO$_2$/Si substrate using the PZT(10/90) and PZT(70/10) metal alkoxide solutions. The effect of heterolayered thin films on the ferroelectrics and electrical properties have been investigated. The lower PZT layers provided the nucleation site for the formation of a perovskite phase of the upper PZT films. Dielectric constant increased with increasing the number of coatings, and it was about 569.9 at PZT-6 heterolayered films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.922-927
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• 2001

Single-layer green ELs was fabricated with using molecularly-dispersed Bu-PBD into poly-N-vinylcarbazole(PVK) which has low operating voltage and high quantum efficiency. A EL cell structure of glass substrate/indium-tin-oxide/PVK:Bu-PBD:C6(∼ 100nm)/Ca(20nm)/Al(20nm) was employed with variable doping concentration. The keys to obtain high quantum efficiency was excellent film forming capability of molecularly dispersed into PVK and appropriate combination of cathode for avoiding exciplex. We obtained the turn-on voltage of 4.2V and quantum efficiency of 0.52% at 0.lmol% of C6 concentration which has been improved about a factor of 50 in comparison with the undoped cell. The PL peak wavelengths wouldn\`t be turned by changing the concentration of the C6 dopant. Green EL emission peak and FWHM were 520nm and 70nm respectively. PL emission peak was obtained at 495nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.1000-1003
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• 2007

The molten carbonate fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. However, the molten carbonate fuel cell which use strongly corrosive molten carbonate at $650^{\circ}C$ have many problem. One of the material problems is the severe corrosion of the metallic components, such as the separator. The effect of coating and annealing treatment on the corrosion for SUS 304 and SUS 430 which are the candidate materials for molten carbonate fuel cell hardware has been investigated in molten carbonate at $650^{\circ}C$ by using steady state polarization and electrochemical impedance spectroscopy method. It was found that the corrosion current of these SUS 304 and SUS 430 decreased with coating and annealing treatment.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.313-318
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• 2001

The sliding wear behavior of Plasma-Sprayed Al$_2$O$_3$-TiO$_2$ Coating against Cemented Carbide were Investigated using a pin on disk type tester. The experiment was conducted using Al$_2$O$_3$-TiO$_2$ Coaling as pin material and Cemented Carbide as disk material and different operating conditions, at room temperature under a dry conditions. The results showed that the type B(250kw power) appeared average wear rate Is lowed than type A(80kw power). The specific wear rate of Specimen A1 Increased with normal load. But The specific wear rate of Specimen B1 decreased with normal load. Average wear rate of specimen A3, B3 are lowed than other but the sliding wear mechanism of edge were rough.