• Journal of the Korean Society for Heat Treatment
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• v.3 no.3
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• pp.13-20
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• 1990

SCM 21 and D.P steel were carburized in vacuum using prophane at a temperature ranging from 1228k to 1308k under a gas pressure ranging from 21.3kpa to 61.8kpa, and the following results were obrained. 1) D.P. steel has considerable efficiency in depressing the grain growth during the high temperature carburizing and it has fine structure even at 1268k for 14.4ks when carburizied. Therefore this steel is expected to be suitable for vacuum carburizing at a high temperature. 2) Case depth was increased as the carburizing temperature increases and it was 3.2mm at max, temperature of 1308k, for max, time of 14.4ks and under max, pressure of 61.8kpa. Thus vacuum-carburizing was considered effective for the materials which need case depth, which is necessary for machine structure use. 3) The rate of case depth of SCM 21 was faster than D.P. steel under same carburizing conditions and the increasing rate of the case depth was constant. 4) Case depth was increased as the gas pressure becomes high under same carburizing temperature. 5) Case carbon concentration, $C_s$, of SCM 21 obeys to a formula, $$C_s=kt^{1/2}+C_0$$ Where k is $2.15{\times}10^{-2}$($wt%.S^{-1/2}$) and this value is a little bit lower than that of SNCM 815.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.419-424
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• 2001

TCV(Temperature control valve by pressure compensation) controls temperature constantly, when it is sending steam or high temperature water to heating device of heat exchanger. For designing TCV, the ratio of piston and hole diameters is one of the important design parameters. Numerical analysis is carried out to elucidate the flow characteristics in the TCV with different port areas of cold and hot waters, using the k-$\epsilon$ turbulence model and Cartesian cut-cell method. Numerical results show that the exit flow rate is mainly affected by pressure distribution in the piston.

• Journal of the Semiconductor & Display Technology
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• v.12 no.2
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• pp.93-98
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• 2013

Nanoimprint lithography (NIL) is a next generation technology for fabrication of micrometer and nanometer scale patterns. There have been considerable attentions on NIL due to its potential abilities that enable cost-effective and high-throughput nanofabrication to the display device and semiconductor industry. To successfully imprint a nanosized pattern with the thermal NIL, the process conditions such as temperature and pressure should be appropriately selected. This starts with a clear understanding of polymer material behavior during the thermal NIL process. In this paper, a filling process of the polymer resist into nanometer scale cavities during the thermal NIL at the temperature range, where the polymer resist shows the viscoelastic behaviors with consideration of stress relaxation effect of the polymer. In the simulation, the filling process and the residual layer formation are numerically investigated. And the effects of pressure and temperature on NIL process, specially the residual layer formation are discussed.

• Journal of Sensor Science and Technology
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• v.12 no.5
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• pp.199-204
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• 2003

This paper describes on the fabrication and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Ta-N thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is $1.097-1.21\;mV/V{\codt}kgf/cm^2$ in the temperature range of $25-200^{\circ}C$ and the maximum non-linearity is 0.43%FS.

• Geomechanics and Engineering
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• v.10 no.4
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• pp.437-454
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• 2016

Wellbore instability problem is one of the main problems that met frequently during drilling, particularly in high temperature, high pressure (HPHT) formations. There are large amount of researches about wellbore stability in HPHT formations, which based on the thermo-poroelastic theory and some achievements were obtained; however, few studies have investigated on the fully coupled thermo-poroelastoplasticity analysis of wellbore stability, especially the analysis of wellbore stability while the filter cake formed. Therefore, it is very necessary to do some work. In this paper, the three-dimensional wellbore stability model which overall considering the effects of fully coupled thermo-poroelastoplasticity and filter cake is established based on the finite element method and Drucker-Prager failure criterion. The distribution of pore pressure, wellbore stress and plastic deformation under the conditions of different mud pressures, times and temperatures have been discussed. The results obtained in this paper can offer a great help on understanding the distribution of pore pressure and wellbore stress of wellbore in the HPHT formation for drilling engineers.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.24-32
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• 2002

The autoignition and subsequent flame propagation of initially nonpremixed turbulent system have been numerically analyzed. The unsteady flamelet modeling based on the RIF (Representative Interactive Flamelet) concept has been employed to account for the influences of turbulence on these essentially transient combustion processes. In this RIF approach, the partially premixed burning, diffusive combustion and formation of pollutants(NOx, soot) can be consistently modeled by utilizing the comprehensive chemical mechanism. To treat the spatially distributed inhomogeneity of scalar dissipation rate, the multiple RIFs are employed in the framework of EPFM(Eulerian Particle Flamelet Model) approach. Computations are made for the various initial conditions of pressure, temperature, and fuel composition. The present turbulent combustion model reasonably well predicts the essential features of autoignition process in the transient gaseous fuel jets injected into high pressure and temperature environment.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.81-89
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• 2002

The autoignition and subsequent flame propagation of initially nonpremixed turbulent system have been numerically analyzed. The unsteady flamelet modeling based on the RIF (representative interactive flamelet) concept has been employed to account for the influences of turbulence on these essentially transient combustion processes. In this RIF approach, the partially premixed burning, diffusive combustion and formation of pollutants(NOx, soot) can be consistently modeled by utilizing the comprehensive chemical mechanism. To treat the spatially distributed inhomogeneity of scalar dissipation rate, the multiple RIFs are employed in the framework of EPFM(Eulerian particle flamelet model) approach. Computations are made for the various initial conditions of pressure, temperature, and fuel composition. The present turbulent combustion model reasonably well predicts the essential features of autoignition process in the transient gaseous fuel jets injected into high pressure and temperature environment.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.73-82
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• 2001

The characteristics of the catalytically supported thermal combustion with Pd-based catalyst using the bench scale high pressure combustor has been investigated up to 7 atm. The emission of $NO_{\chi}$ depends on the preheating temperature and the excess air ratio. Most $NO_{\chi}$ emission seems to come from the pre-burner for the preheating of the inlet gas. Decreasing excess air ratio in the inlet gas below 1.5 results in the stable catalytically supported thermal combustion in the post combustion region while the $NO_{\chi}$ emission increased up to 15 ppm. Further, the increase of the pressure shows the dramatic increase of the emission CO and THC. However, the $NO_{\chi}$ emission decreased slightly due to the lower combustion temperature at the high pressure.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.961-968
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• 1996

The aluminum nitride was synthesized by the self-propagating high-temperature synthesis(SHS). The synthe-sis was used aluminum powder mixed with AlN powder as reactant and the control factors affected to synthesis were considered compact density pressure of reaction gas AlN diluent content and aluminum powder size. The SHS reaction conducted with a reactant containing 50% AlN diluent under 0.8MPa nitrogen gas pressure yielded a complete conversion of aluminum powder to AlN powders. The size and purity of AlN produced were found to be comparable with that of AlN produced by the carbothermal nitrogen method.

• Carbon letters
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• v.13 no.4
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• pp.205-211
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• 2012

Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.