• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.30-31
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• 2006

To improve the mean-life and the reliability of power cable, we have investigated specific heat (Cp). Specific-heat measurement temperature ranges of XLPE insulator were from $20[^{\circ}C]$ to $90[^{\circ}C]$, and the heating rate was $1[^{\circ}C/min]$. In case of semiconducting materials, the measurement temperature ranges of specific heat were from $20[^{\circ}C]$ to $60[^{\circ}C]$ and the heating rate was $1[^{\circ}C/min]$. From these experimental results, both specific heat were increased by heating rate because volume of materials was expanded according to rise in temperature. We could know that a small amount of CNT has a excellent thermal properties.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.54-59
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• 2008

Hydrated sodium silicate with 25 wt% water contents was synthesized by hydrothermal reaction using anhydrous sodium silicate. The hydrated sodium silicate was expanded at $370^{\circ}C$ for 30 min. and then pulverized, classified (- 200 mesh) and press-formed. The samples were heat treated at $400{\sim}900^{\circ}C$ for 30 min. in order to study the expansion characteristics depending on heat treatment temperature. A porous body with closed pore was formed above $600^{\circ}C$. The volume expansion ratio and the pore size were increased and the specific gravity was decreased with increasing heat treatment temperature. However, the volume expansion ratio was decreased and the specific gravity was increased above $850^{\circ}C$ due to the softening of the sodium silicate.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.830-836
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• 2001

An one-zone heat release analysis was studied for a 4 cylinder indirect diesel engine. The object of the study is to calculate the heat release accurately including the effect of specific heat ratio, heat transfer and crevice volume and to find out combustion characteristics of an indirect diesel engine cosidering the effect of both pressure in the main and swirl chambers. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.19-24
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• 2005

To improve mean-life and reliability of power cable, we have investigated specific heat (Cp) and thermal conductivity of XLPE insulator and semiconductive materials in 154kV underground power transmission cable. Specimens were respectively made of sheet form with EVA, EEA and EBA added 30wt%, carbon black, and the other was made of sheet form by cutting XLPE insulator in 154kV power cable. Specific heat (Cp) and thermal conductivity were· measured by DSC (Differential Scanning Calorimetry) and Nano Flash Diffusivity. Specific-heat measurement temperature ranges of XLPE insulator were from 20[$^{\circ}C$] to 90[$^{\circ}C$], and the heating rate was 1[$^{\circ}C$/min]. And the measurement temperatures of thermal conductivity were 25[$^{\circ}C$}], 55[$^{\circ}C$] and 90[$^{\circ}C$]. In case of semiconductive materials, the measurement temperature ranges of specific heat were from 20[$^{\circ}C$] to 60[$^{\circ}C$], and the heating rate was 1[$^{\circ}C$/min]. And the measurement temperatures of thermal conductivity were 25[$^{\circ}C$] and 55[$^{\circ}C$]. From these experimental results, both specific heat and thermal conductivity were increased by heating rate because volume of materials was expanded according to rise in temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.6-10
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• 2006

To improve mean-life and reliability of power cable, we have investigated specific heat (Cp) and thermal conductivity of XLPE insulator and semiconducting materials in 154(kV) underground power transmission cable. Specimens were respectively made of sheet form with EVA, EEA and EBA added $30[wt\%],$ carbon black, and the other was made of sheet form by cutting XLPE insulator in 154(kV) power cable. Specific heat (Cp) and thermal conductivity were measured by DSC (Differential Scanning Calorimetry) and Nano Flash Diffusivity. Specific-heat measurement temperature ranges of XLPE insulator were from $20[^{\circ}C]\;to\;90[^{\circ}C],$ and the heating rate was $1[^{\circ}C/mon].$ And the measurement temperatures of thermal conductivity were $25[^{\circ}C],\;55[^{\circ}C]\;and\;90[^{\circ}C].$ In case of semiconducting materials, the measurement temperature ranges of specific heat were from $20[^{\circ}C]\;to\;60[^{\circ}C],$ and the heating rate was $1[^{\circ}C/mon].$ And the measurement temperatures of thermal conductivity were $25[^{\circ}C],\;55[^{\circ}C].$ In addition we measured matrix of semiconducting materials to show formation and growth of carbon black in base resins through the SEM. From these experimental results, both specific heat and thermal conductivity were increased by heating rate because volume of materials was expanded according to rise in temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.120-131
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• 1995

Thermodynamic analysis of extraction process from the constant pressure LNG(Liquefied Natural Gas) vessel was performed in this study. LNG was assumed as a binary mixture of 90% methane and 10% ethane by mole fraction. The thermodynamic properties such as temperature, composition, specific volume and the amount of cold energy were predicted during extraction process. Pressure as a parameter ranges from 101.3kPa to 2000kPa. The result shows the peculiar phenomena for the LNG as a mixture. Both vapor and liquid extraction processes were investigated by a computer model. The property changes are negligible in the liquid extraction process. For the vapor extraction process, the temperature in the vessel increases rapidly and the extracted composition of methane decreases rapidly near the end of extracting process. Specific volume of vapor has the maximum and that of liquid has the minimum during the process. When pressure is increased, specific volume of vapor decreases and that of liquid increases. It was found that specific volume of vapor phase had a major effect on the heat absorption at constant pressure during vapor extraction process. If the pressure of the vessel increases, the total cold energy which can be utilized from LNG decreased.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.640-645
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• 1995

Job's-tears(Coix lachryma-jobi L. var. Ma-yuen Stapf) seeds were processed to flakes by soaking, heat treatment, intermediate-moisture drying, flaking, drying, and cooking. Some functional properties of job's-tears flakes subjected to varing degree of heating were characterized by specific volume, texture, water absorption index(WAI), water solubility index(WSI), and viscosity. As degree of gelitinization increased within the intermediate range of $60{\sim}70%$, steam-cooked Job's-tears demonstrated appropriate rheological properties for further processes, resulting in increased specific volume and decreased breaking strength. However, excessive heat treatment rendered Job's-tears undesirably sticky for flaking, which caused adverse effects on the functional properties of flakes such as specific volume and breaking strength. Increasing steaming time$(5{\sim}30\;min)$ caused an increase in WAI and WSI values. Apparent viscosity of powdered flakes was increased with the extent of gelitinization as a function of heat processing. Viscosity of powdered flakes determined using the amylograph increased with the degree of heating applied to Job's-tears at low pasting temperatures, accompanied by a decrease in maximum viscosity as the pasting temperature increased.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2358-2367
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• 1992

This paper deals with preliminary design conditions for a thermally actuated Vuilleumier refrigerator/heat pump. The previously reported approximate adiabatic analysis which is based on the 8-volume model makes it possible to evaluate exchanged heats per cycle as well as cyclic pressure, temperature and mass variation of each working volume. Calculated results reveal not only there exists an optimum value for the phase angle and the swept volume ratio maximizing a specific thermal output, but also design parameters can be determined independently of each other. Under a given combination of operating temperature levels, the optimum conditions for refrigeration are different from those for heat pumping and the differences between two operating modes become larger with decreasing the dead volume ratio. Both the optimum phase angle and the optimum swept volume ratio are increased asymptotically toward 0.5 pi and 1.0 respectively, as the dead volume ratio approaches to unity. When a VM machine is used for cooling and heating simultaneously, the design parameters should be carefully determined to reach the best performance.

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.29-36
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• 1991

Microporous glasses in the system TiO2-SiO2-Al2O3-B2O3-CaO-Na2O were prepared by the phase-separation technique. Morphology and distribution of pore and specific surface area of glasses heated and leached out at various conditions were investigated by SEM and Porosimeter. Crystallization of glasses heated above transition temperature was also inspected by X-ray diffraction method. When the heating temperature and time increased, the pore size and volume increased, but the specific surface area decreased above the critical temperature. The phase-separation, specific surface area and pore size showed more sensitive change on the variation of heating temperature than of heating time. The specific surface area and micropore volume of porous glasses prepared in this study were about 120-330$m^2$/g and 0.001-0.01cc/g, respectively. Mean pore size of porous glasses were about 20-90$\AA$. Anatase phases was deposited when the parent glass was heat-treated at 75$0^{\circ}C$ for 6hrs.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.79-83
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• 2015

Hydrogen has long been recognized as a fuel having some unique and highly desirable properties, for application as a fuel in engines. Hydrogen has some remarkably high values of the key properties for transport processes, such as kinematic viscosity, thermal conductivity and diffusion coefficient, in comparison to those of the other fuels. Such differences together with its extremely low density and low luminosity help to give hydrogen its unique diffusive and heat transfer characteristics. The thermodynamic and heat transfer characteristics of hydrogen tend to produce high compression temperatures that contribute to improvements in engine efficiency and lean mixture operation.