• Journal of Surface Science and Engineering
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• v.24 no.4
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• pp.222-229
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• 1991

The oxidation behavior of Ni-6wt.% Cr alloys with various concentration of alumina dispersions(5vol.% 10vol.%) was determined at 1000 and 110$0^{\circ}C$ in oxygen of 1 atm. pressure. Some general observations were ascertained. These include: (a) the addition of alumina dispersoids significantly increased the oxidation resistance of Ni-6wt.% Cr alloy; (b) the rate of oxidation was distinctly decreased as a function of the volume percent of oxide dispersion; and (c) the presence of alumina dispersions promoted the formation of continous, protective Cr2O3 layer at 6 wt.% Cr.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.670-678
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• 1999

Heat recovery steam generator(HRSG) is a principal component of the combined cycle power plant (CCPP) which utilizes the waste energy of the gas turbine exhaust gas. A design of the HRSG is a keypoint to achieve high cycle efficiency with competitive cost. This paper presents a brief review on the design of a HRSG which covers the basic design parameters and their effects on the performance and the investment cost. Finally the concept of the optimum design point is presented according to the selection of a pinch point temperature difference and a steam pressure as an illustrated case.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.145-148
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• 2011

The thermal behavior of lithiated Si anodes has been investigated using differential scanning calorimetry (DSC). In particular, the effect of Si particle size on the thermal stability of a fully lithiated Si electrode was investigated. For DSC measurements, a lithiated Si anode was heated in a hermetically sealed high-pressure pan with a polyvinylidene fluoride (PVDF) binder and a 1 M $LiPF_6$ solution in an ethylene carbonate (EC)-diethyl carbonate (DEC) mixture. The thermal evolution around $140^{\circ}C$ increases with lithiation and with decreasing particle size; this phenomenon is attributed to the thermal decomposition of the solid electrolyte interface (SEI) film. Exothermic peaks, following a broad peak at around $140^{\circ}C$, shift to a lower temperature with a decrease in particle size, indicating that the thermal stability of the lithiated Si electrode strongly depends on the Si particle size.

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.959-961
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• 2001

Nanosized CeO$_2$Powders were prepared under high temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Spherical shape of CeO$_2$powder was obtained at 175$^{\circ}C$ for 6h. TEM and X-ray diffraction patterns showed that the synthesized particle was crystalline. The average size and size distribution of the synthesized particles were below 30 nm and narrow, respectively. In addition, the effects of synthesis parameters under hydrothermal process are discussed.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.575-582
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• 1998

Sutiability of Jungsan clay shale dolomite sludge Anyang feldspar and alumina as raw materials for light-weight porous ceramics was examined. In order to find optimum manufacturing conditions compositions heating temperatuers and heating times were varied and their effects on physical properties were measured and bloating mechanism was investigated. Jungsan clay seems suitable as raw material to make the light-weight constructional materials with 5wt% of ANyang feldspar and alumina added in calcined clay (800$^{\circ}C$) having bulk density of 0.45g/cm3 water absorption of 1.34% and compressive strength of 85kg/cm2 rapid-heated at 1200$^{\circ}C$ for 30min. It is suggested that bloating mechanism depends on the difference of tem-peratures between the inside and outside in specimen the remained gases in interstices can bloat by the li-quid phase of surface with high viscosity and gas pressure at elevated temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.4
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• pp.33-42
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• 1994

The radiative heat transfer analysis in the fluidized particles layer has important application in many technological areas such as combustion chambers at high pressure and temperature, plasma generators for nuclear fusion, MHD generator using pulverized coal and the liquid droplet radiator used to reject wasted heat from a power plant operating in space. To accurately model the radiation properties of the fluidized particles layer, it is necessary to know the radiation interchange factors of particles in each layer. But the solutions are usually not possible for the equations of radiative heat transfer because it has an inherent difficulty in treating the governing intergo- differential equations, which are derived from the remote effects of radiative heat transfer. In this study, the analysis uses the Monte Carlo simulation method with optical depth model to calculate the radiation interchange factors of particles in each layer with wall and with each other.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1692-1696
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• 2004

This paper presents the thermally induced hot spot characteristics of rubbing surface in the friction pad disk brake. During the braking period, the rubbing surface with irregular asperities that are strongly engaged in rough surface, wear, and deformed surface due to a friction heating may produce an irregular distorted geometry of the disk surface. The tribological interactions between the disk and the pads are unstable if the contact stress is severe, in which the irregularity develops the contact pressure distribution, leading eventually to localized contact, high temperature and formation of hot spots. The computed results of contact spots that are simulated using a coupled thermal-mechanical analysis present sinusoidal distortions and localized extrusions of the disk surface, which are strongly related to a hot spot in the practical disk brake.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.514-521
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• 2008

Many research works for improving a boundary lubrication performance have been executed by using solid lubricants, and been tried to apply an engine lubrication. However those general lubricants have not been applied on engines due to the extreme conditions such as very high temperature and pressure during combustion process in a cylinder. In this study a lubricant containing copper alloy nano-powder is applied on a diesel engine driven by an electric motor. Torques and shaft vibrations are measured, then an engine friction loss and rotating stability are assessed. The results show that the frequency of the vibration is about the same as that of a general lubricant, but the amplitudes in the both X and Y direction are reduced as well as the friction loss is reduced.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.117-123
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• 2011

The purpose of this study is to show the friction and wear characteristics on the vapor deposited coating layers on the SCM415 steel. In this research, frictional wear characteristic of coating materials such as Ti-series, Cr-series & WC/C and TiAlN+WC/C multilayer coating was investigated under room temperature, normal air pressure and no lubricating condition. Therefore, this study carried out research on the friction coefficient, micro hardness(Hv), surface roughness and wear quantity on the vapor deposited coating layers on the SCM415 steel. As the wear experimental result, the excellence of TiAlN+WC/C multilayer coating has been proven by high micro-hardness, low friction coefficient and wear quantity.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.76-81
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• 2008

Nanoimprint lithography(NIL) is an emerging technology enabling cost-effective and high-throughput nanofabrication. Among NILs, significant efforts from both academia and industry have been put in UV NIL research and development because of its ability to pattern at room temperature and at low pressure. In UV NIL, there may be in-line set-up error of the stamp and the substrate. To compensate this error, the dummy blocks are put on the stamp and pressurized uniformly. Contact problems between the stamp and the photoresist layer on the substrate are often happened, which results in the non-uniform residual layer In this paper, the pressurization method on the dummy block is investigated by the finite element method. A new method is recommended and evaluated far the uniform stamp deformation.