• Journal of Hydrogen and New Energy
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• v.34 no.5
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• pp.549-554
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• 2023

In this paper, three kinds of studies have been completed to obtain highly purified carbon dioxide having more than 7N purity as an electronic grade quality. PRO/II with PROVISION release January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the cryogenic distillation process. When using LN2 cold heat, we can obtain highest recovery of carbon dioxide as a bottom product for a cryogenic distillation column.

• Journal of applied mathematics & informatics
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• v.9 no.2
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• pp.731-744
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• 2002

The temperature distribution in human skin and subdermal tissue layer is presented using bioheat transfer equation. The body temperature is determined by the balance between heat produced and heat lost by our body. The time-dependent solutions have been found to be affected by the metabolic heat generation rate, blood mass flow, the rate of evaporation of perspiration and also by the atmospheric temperature. The analytic solutions for different layers have been calculated numerically and are also shown graphically.

• Journal of the Korean Mathematical Society
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• v.57 no.2
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• pp.313-329
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• 2020

In this paper, we derive various differential Harnack estimates for positive solutions to the nonlinear backward heat type equations on closed manifolds coupled with the Ricci-Bourguignon flow, which was done for the Ricci flow by J.-Y. Wu [30]. The proof follows exactly the one given by X.-D. Cao [4] for the linear backward heat type equations coupled with the Ricci flow.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.79-84
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• 1998

It is very difficult to analyze the transient temperature distribution during quenching of the steel because of coupled effects among temperature, structures and stresses. In this paper, using Inoue's equation of evolution and mixture rule, transient temperature distribution is calculated by the finite element method considering latent heat of transformation structure and temperature dependence of physical and mechanical prperties for the 0.45% carbon cylindrical steel bar with 40mm diameter and 20mm height during end-quenching.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.4
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• pp.773-784
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• 2010

The existence of solutions in Besov spaces for nonlinear heat equations having transcendental nonlinearity: $$\frac{\partial}{{\partial}t}u-{\Delta}u=F(u)$$ is investigated. In particular, it is proved the local existence and blow-up phenomena of the solutions in Besov spaces for nonlinear heat equations corresponding to two transcendental nonlinear functions $F(u){\equiv}{\mid}u{\mid}e^{u^2}$ and $F(u){\equiv}e^u$ of rapid growth.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.32-35
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• 2012

The objective of the present work is to develop a precise instrument for measuring the thermal property of insulating material over a temperature range from 30 K to near room temperature by utilizing a cryocooler. The instrument consists of two thermal links, a test sample, heat sink, heat source and vacuum vessel. The cold head of the cryocooler as a heat sink is thermally anchored to the thermal link and used to bring the apparatus to a desired temperature in a vacuum chamber. An electric heater as a heat source is placed in the middle of test sample for generating uniform heat flux. The entire apparatus is covered by thermal shields and wrapped in multi-layer insulation to minimize thermal radiation in a vacuum chamber. For a supplied heat flux the temperature distribution in the insulating material is measured in steady and transient state. The thermal conductivity of insulating material is measured from temperature difference for a given heat flux. In addition, the specific heat of insulating material is obtained by solving one-dimensional heat diffusion equation.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.88-95
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• 2012

In this study, in order to utilize the seawater as a heat source at Gangneung city near the East Sea in Korea, an annual heating performance of a screw heat pump was simulated. For a simulation, the maximum heating capacity of heat pump was assumed at 3.5 MW. An ambient temperature at Gangneung city was calculated from the TMY2 weather data, while the seawater temperature was calculated from the regression equation based on the measurement by the National Fisheries Research and Development Institute of Korea. The heating load was assumed linearly dependent on the ambient temperature, while the maximum heating load was assumed to appear when the ambient temperature is below $-2.4^{\circ}C$, which is the temperature of TAC 2.5% for heating at Gangneung city. A heat pump performance at full-load was calculated from the regression equation, which involves refrigerant's evaporating and condensing temperatures, based on a commercial screw compressor performance map. A heating supply temperature which determines refrigerant's condensing temperature was assumed linearly dependent on the heating load. A performance degradation due to the part-load operation of heat pump was also considered. Simulation results show that an annual heating coefficient of performance ($COP_H$) of a seawater-source screw heat pump is approximately 2.8 and that it is necessary to improve part-load performance to increase an annual performance of the heat pump.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.488-493
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• 2012

In this study, in order to utilize the seawater as a heat source at Gangneung city near the East Sea in Korea, an annual heating performance of a screw heat pump was simulated. For a simulation, the maximum heating capacity of heat pump was assumed at 3.5 MW. An ambient temperature at Gangneung city was calculated from the TMY2 weather data, while the seawater temperature was calculated from the regression equation based on the measurement by the National Fisheries Research and Development Institute of Korea. The heating load was assumed linearly dependent on the ambient temperature, while the maximum heating load was assumed to appear when the ambient temperature is below $-2.4^{\circ}C$, which is the temperature of TAC 2.5% for heating at Gangneung city. A heat pump performance at full-load was calculated from the regression equation, which involves refrigerant's evaporating and condensing temperatures, based on a commercial screw compressor performance map. A heating supply temperature which determines refrigerant's condensing temperature was assumed linearly dependent on the heating load. A performance degradation due to the part-load operation of heat pump was also considered. Simulation results show that an annual heating coefficient of performance ($COP_H$) of a seawater-source screw heat pump is approximately 2.8 and that it is necessary to improve part-load performance to increase an annual performance of the heat pump.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.65-71
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• 2003

In this research, we make the thin wall chamber to the measurement of heat flux of using a Kerosene/LOx liquid rocket engine's thrust chamber. The wall thickness is one millimeter. We measured outside wall temperature of thrust chamber by nine thermocouple. We suppose the system to the one-dimension unsteady state, and so the heat flux and heat transfer coefficient of thurst chamber are calculated using one-dimensional the transient energy equation by outside wall temperature. In this case, O/F ratio is 2.0, experimental variation is chamber pressure and we got the heat transfer coefficient of the proportion relation of 0.88 times for the chamber pressure.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.77-83
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• 2010

Purpose: The aim of this study was to do numerical analysis of the wavelength dependence in low level laser therapy (LLLT) using a finite element method (FEM). Methods: Numerical analysis of heat transfer based on a Pennes' bioheat equation was performed to assess the wavelength dependence of effects of LLLT in a single layer and in multilayered tissue that consists of skin, fat and muscle. The three different wavelengths selected, 660 nm, 830 nm and 980 nm, were ones that are frequently used in clinic settings for the therapy of musculoskeletal disorders. Laser parameters were set to the power density of 35.7 W/$cm^2$, a spot diameter of 0.06 cm, and a laser exposure time of 50 seconds for all wavelengths. Results: Temperature changes in tissue based on a heat transfer equation using a finite element method were simulated and were dominantly dependent upon the absorption coefficient of each tissue layer. In the analysis of a single tissue layer, heat generation by fixed laser exposure at each wavelength had a similar pattern for increasing temperature in both skin and fat (980 nm > 660 nm > 830 nm), but in the muscle layer 660nm generated the most heat (660 nm ${\gg}$ 980 nm > 830 nm). The heat generation in multilayered tissue versus penetration depth was shown that the temperature of 660 nm wavelength was higher than those of 830 nm and 980 nm Conclusion: Numerical analysis of heat transfer versus penetration depth using a finite element method showed that the greatest amount of heat generation is seen in multilayered tissue at = 660 nm. Numerical analysis of heat transfer may help lend insight into thermal events occurring inside tissue layers during low level laser therapy.