• Geosystem Engineering
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• v.21 no.6
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• pp.309-317
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• 2018

We employ a three-dimensional indirect boundary element method (BEM) to simulate temperature change around an underground liquefied natural gas storage cavern. The indirect BEM (IBEM) uses fictitious heat source strength on boundary elements as basic variables which are solved from equations of boundary conditions and then used to compute the temperature change at other points in the considered problem domain. The IBEM requires evaluation of singular integration for temperature change due to heat conduction from a constant heat source on a planar (triangular) region. The singularity can be eliminated by a semi-analytical integration scheme. However, it is found that the semi-analytical integration scheme yields sharp temperature gradient for points close to vertices of triangle. This affects the accuracy of heat flux, if they are evaluated by finite difference method at these points. This difficulty can be overcome by a combination of using a direct numerical integration for these points and the semi-analytical scheme for other points distance away from the vertices. The IBEM and the hybrid integration scheme have been verified with an analytic solution and then used to the application of the underground storage.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.84-92
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• 2002

On the cold start of LPG engine, as the engine temperature has not reached its equilibrium temperature, liquid LPG could not be changed perfectly gaseous LPG, although it was passed to the vaporizer. Liquid and gas mixed fuel could influence starting ability and exhaust emission characteristics of LPG engine. In this study, the vaporization characteristic of liquid LPG was investigated with a conventional vaporizer and the vaporizer with heat source(glow plug) installed at preheated chamber inlet, by using the visualization methods and engine test. According to visualization result, even if the engine coolant temperature was $14^{\circ}C$, liquid fuel was supplied to primary chamber over 25 seconds without vaporizing from preheated chamber in such a conventional vaporizer. However, the vaporizer with heat source do not correspond with that, scarcely had been trim on glow plug when LPG began to vaporize. The effectiveness of heat source could be verified by application to the conventional LPG engine.

• Journal of computational fluids engineering
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• v.10 no.1
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• pp.94-98
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• 2005

Accurate prediction of the fire-induced air velocity, temperature and smoke flow in underground utility tunnel becomes more important for the optimization of design and placement of heat and smoke detectors. In order to improve the safety of underground utility tunnel systems, the behaviors of fire-induced smoke flow and temperature distributions are investigated. Especially, two different cross-sectional shapes of tunnel, such as rectangular and circular types are modeled. Also, fire source is modeled as a volumetric heat source. Three-dimensional thermal-flow characteristics in an underground tunnel are solved by means of FVM using SIMPLE algorithm. The effects of shape geometry on the fire-induced flow characteristics are graphically depicted. It is desirable that heat and smoke detectors are installed on the cables and the top of the wall.

• Proceedings of the Korean Printing Society Conference
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• 2007.11a
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• pp.75-81
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• 2007

As manufacturing the low temperature firing paste applicable flat light source for LCD BLU, this study examined the specific quality. For the phosphor pastes, the low temperature firing acryl resin is used as the binder resin. As the result of thermal decomposition characteristics, residual hydroxylcarbon rested under 0.1wt% on 400$^{\circ}C$. With the manufactured paste in this study, the flat light source device is manufactured through the screen printing and it brought the almost 100% of special quality radiation about the phosphor brightness.

• Journal of the Korean Graphic Arts Communication Society
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• v.22 no.2
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• pp.151-162
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• 2004

MnSb layers were grown on GaAs(100), (111)A and (111)B substrates by hot wall epitaxy under various growth conditions. Growth condition dependence of structural properties of the layers was examined. The growth direction and structural properties of MnSb/GaAs(100) depend on Sb source and substrate temperatures. The smooth MnSb(10.1)/GaAs(100) interface was obtained under the appropriate growth condition. On the other hand, MnSb(00.1) layers were grown on GaAs(111) substrates. The quality of the layers on (111)B was superior to that on GaAs(111)A, but degraded as in increasing Sb source temperature during the growth. The $Mn_2Sb$ domain was generated in the layers grown under conditions of low Sb source temperature and high substrate temperature on GaAs(111) substrates.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.265-271
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• 2003

This study is for the stable optical source in order to get the precision measurement, which contributes to help the laser frequency and the output to be settled. The laser optical frequency is changed by the length of resonance cavity. The length variation of the laser resonance amplitude is affected by the thermal expansion of that system. So, we try not only to adjust the temperature of the laser tube using the heater for fine length of resonance cavity, but also to maintain the fixed temperature of the resonance cavity for outputting the safe laser optical frequency. Therefore, we must take materials with the thermal expansion of the supporting system, which is closer to it of the laser resonance cavity. Using the materials, we can promote to stabilize the temperature of it. In advance, we also plan to get the settlement of the laser frequency and the output in the long km, optimizing and stabilizing the system.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.191-194
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• 2011

Low-grade waste heat has generally been discarded in industry due to lack of efficient recovery methods. In recent years, organic Rankine cycle(ORC) has become a field of intense research and appears as a promising technology for conversion of heat into useful work of electricity. In this work thermodynamic performance of ORC with superheating of vapor is comparatively assessed for various working fluids. Special attention is paid to the effects of system parameters such as the evaporating temperature on the characteristics of the system such as maximum possible work extraction from the given source, volumetric flow rate per 1 kW of net work and quality of the working fluid at turbine exit as well as thermal efficiency.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.62-66
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• 2013

Overlay welding is carried out to improve the corrosion resistance, wear resistance and heat resistance on the surface of the chemical plant and steelmaking plant structures. In overlay welding, control of the bead size and the temperature distribution of weldment are particularly important because that is directly connected to the improvement of quality and productivity. The aim of this study is to model the welding heat source that is very useful to analyze the bead size and temperature distribution of weldment. To find the welding heat source model, numerical analyses are performed by using FE software MSC-marc.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2231-2235
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• 2008

Thermal performance of fusing system in laser printer is determined by FPOT(First print out time) required and toner fusing quality. FPOT is influenced by the thermal resistance of fusing system between heat source and nip region. Also FPOT is depended by the heat source power and toner fusing temperature. The fusing quality of toner is decided by the temperature, pressure and duration time in nip region. In this study, I have performed thermal analysis for the toner fusing system. Computational simulation has been used to understand the effect of heat source power and printing speed etc. on the temperature distribution of the fusing system. Also in order to predict fusing quality, numerical simulation of the process that paper is continuously supplied to the nip regions were performed. In comparison with the experimental results of the fusing quality vs transferred calory to the toner layer, I could evaluate various fusing condition parameters effected on the thermal performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.101-104
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• 1992

In-doped CdS thin films have been deposited at 150$^{\circ}C$ by simultaneous thermal evaporation of CdS and In. Deposition rate and film thickness were 8A/sec and about 1um, respectively. Indium doping concentration of films varied as Indium source temperature from 500$^{\circ}C$ to 700˚. Properties of In-CdS films have been investigatied by measurements of electrical resistivity, Hall effect, X-ray diffraction and optical trasmission spectra. The conductivity of these films was always n-type. The resistivity, carrier concentration, mobility and optical band gap dependence on Indium source temperature are reported. Carrier concentration and mobility of In-CdS films increased with increasing Indium source temperature: then they decreased. The variation of the optical band gap of In-CdS thin films are related to carrier concentration.