• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.35-43
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• 2002

This research makes that quantitative radiation property of an actual town ward is obtained in quest of the parameter with regard to a radiation heat transfer property and set up several town ward models that reproduced a solid form of a city along the attribute of the city. A regular trend possibility that is able to evaluate a radiation characteristics of a town ward quantitatively from a town ward guideline and confirmation that is produced about each parameter as a result of a numerical value simulation it obtained. This research shot a coefficient of Gebhart's emission absorption. sky radiation absorption rate direct solar radiation absorption rate the parameter with regard to a radiation heat transfer characteristics of a town ward in each town ward model and a volume rate of a town ward advances case study under regular such condition and shot the absorption rate, direct and others days and calculated an absorption rate and checked about the relation between a town ward and each radiation heat transfer property of a city.

• Journal of Mechanical Science and Technology
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• v.15 no.2
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• pp.239-247
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• 2001

Measured radiative heat fluxes on the furnace exit plane of a heavy duty power boiler of steam output 1650 T/h are discussed. A high-ash pulverized bituminous coal was used. Such measurements are necessary to improve heat fluxes inside a steam boiler furnace was manufactured. An extra small heat radiation sensor was placed in the water cooled head of the probe. The sensor had no direct contact with furnace gases and measured only the radiant energy. There was no exposure to convective heat transfer. With the radiometric probe, one can obtain a spherical indicatrix of radiation intensity as well as hemispherical radiative heat flux incident on any surface passing through a measuring point inside the furnace. Thus, the quantity of radiation energy, passing through the furnace exit plane, to the convective heating surfaces and the quantity of radiation energy going in the opposite direction were measured. A formula for relative radiative heat flux on the furnace exit plane has been proposed.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1530-1535
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• 2011

Heat radiation of LED luminaires has risen a problem when applied indoor. LEDs can save energy with higher efficacy than other light sources. However, their heat radiation may increase power consumption for air-conditioning. Therefore, this paper carried out a comparative analysis on the amount of heat radiation for MR16, E26 bulb, and down-light which will be replaced to LED luminaires. Heat amount of LED-MR16 and LED-downlight was 48% and 87.5% lower than that of conventional lamps, halogen MR16 and E26 CFL, respectively. Consequently, the heat amount and indoor temperature were proportional to the power consumption of luminaire. Therefore, the use of LED luminaire can reduce the amount of heat radiation as well as power consumption.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.150-156
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• 2017

This study tests the characteristics of heat radiation by applying the pin-height variables to 30-W LED floodlights. The angle of the heat sink enables us to identify the characteristics of the heat radiation based on the temperature distribution. The results of the study are as follows. When the heat sinks are set towards the ground, the heat transfer decreases in speed only to expands the temperature distribution, which adversely affects the characteristics of heat radiation and expands the temperature distribution of PCB with the LED chip. We verify that the characteristics of heat radiation are adversely affected when the height of the cooling pin decreases and the heat radiation area decreases, which impedes the heat transfer and increases the temperature distribution on the heat sink.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1156-1165
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• 2002

The characteristics of combustion and radiation heat transfer of an oxygen-enhanced diffusion flame was experimentally analyzed. An infrared radiation heat flux gauge was used to measure the thermal radiation of various types of flames with fuel, air and pure oxygen. And the Laser Induced Incandescence (LII) technique was applied to characterize the soot concentrations which mainly contribute to the continuum radiation from flame. The results show that an oxygen-enhanced inverse diffusion flame is very effective in increasing the thermal radiation compared to normal oxygen diffusion flame. This seems to be caused by overlapped heat release rate of double flame sheets formed in inverse flame and generation of higher intermediate soot in fuel rich zone of oxygen-fuel interface, which is desirable to increase continuum radiation. And the oxygen/methane reaction at slight fuel rich condition (ø=2) in oxygen-enhanced inverse flame was found to be more effective to generate the soot with moderate oxygen availability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3344-3354
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• 1996

An experimental and numerical study on the three-dimensional natural convection-radiation conjugate heat transfer in the enclosure with heat generating chip has been performed. A 3-dimensional simulation model is developed by considering heat transfer phenomena by conduction-convection and radiation. Radiative transfer was analyzed with the discrete ordinates method. Experiments are conducted in order to validate the numerical model. Comparisons with the experimental data show that good agreement is obtained when the radiation effect is considered. The effects of the thermal conductivity of the substrate and power level on heat transfer are investigated. It is shown that radiation is the dominant heat transfer mode and the conductivity of the substrate has important effects on the heat transfer in the enclosure.

• Fire Science and Engineering
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• v.31 no.2
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• pp.17-23
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• 2017

The test methods using convection (flame) and radiation heat sources were compared to evaluate the thermal protective performance of the firefighter's protective clothing. In particular, the influence of the outer shell, mid-layer, and lining constituting the firefighter's protective clothing on the thermal protective performance was compared for convection and radiation heat sources. Tests for the thermal protective performance were carried out according to KS K ISO 9151 (convection), KS K ISO 6942 (radiation), and KS K ISO 17492 (convection and radiation). When tested under the same incident heat flux conditions ($80kW/m^2$), the heat transfer index ($t_{12}$ and $t_{24}$) for the radiation heat source was higher than that for the convection heat source. This means that radiation has a lesser effect than convection. For the convection heat source, the lining had the greatest effect on the thermal protective performance, followed by the mid-layer and the outer shell. On the other hand, for the radiation heat source, the effect on the thermal protective performance was great in the order of lining, outer shell, and mid-layer. Convection and radiation have fundamentally different mechanisms of heat transfer, and different heat sources can lead to different thermal protective performance results depending on the material composition. Therefore, to evaluate the thermal protective performance of the firefighter's protective clothing, it is important to test not only the convection heat source, but also the radiation heat source.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.111-113
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• 2007

Thermal conductivities of copper thin films on silicon wafer was obtained from temperature distribution on the surface of wafer measured by radiation thermometry, when sample was heated with constant temperature ate the both ends in a vacuum and dissipate heat by radiation heat transfer into an environment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.542-550
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• 1998

A direct contact heat exchanger using particle-suspended gas as a heat transfer medium is analyzed with an extended emphasis on the radiation, i. e., considering the radiation by both gas and particles. While the Runge-Kutta method is used for a numerical analysis of the momentum and energy equations, the finite volume method is utilized to solve the radiative transfer equation. Present study shows a notable effect by the gas radiation in addition to the particle radiation, especially when changing the chamber length as well as the gas and particle mass flow rate. When the gas and particle mass flow rate is raised, the gas temperature in the particle heater still increases as the gas absorption coefficient increases, which is different from the results for the small scale heat exchanger.

• Journal of Radiation Industry
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• v.7 no.2_3
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• pp.183-190
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• 2013

Mistletoe (Viscum album) has been widely used as a functional food material for various therapeutic purposes from ancient time. In this study, we examined anti-diabetic and cytotoxic activities of heated-treated mistletoe and the effects of gamma-irradiation on its activities. Heat-treated mistletoe extract was prepared by heating during different time (3, 6, 9 and 12 h) and gamma-irradiated with different doses of 0, 10, 30, 50, 70 and 100 kGy. Heat-treated mistletoe extracts showed a concentration-dependent cytotoxicity on rat insulinoma RINm5F cells and the effect was gradually decreased as heating time increased up to 12 h. 12 h heat-treated extract was no cytotoxic. Gamma-irradiation enhanced the reduction of heat-treated mistletoe-induced cytotoxicity and the decreasing effect was an irradiating dose-dependent. In particular, all of 70 kGy irradiated and heat-treated mistletoe extracts did not showed the cytotoxicity and the effect was comparable to 12 h heat-treated mistletoe extract. Among those extracts, 3 h heat-treated mistletoe extract gradually increased the insulin secreting activity by gamma-irradiation and the effect was the best at 70 kGy, whereas 12 heat-treated extract was no effect. On the test of ${\alpha}$-glucosidase inhibitory activity, 3 h heat-treated mistletoe extract showed the concentration dependent effects and gamma-irradiation induced more activity at 70 kGy, compared to non-irradiated 3 h and 12 h heated mistletoe extracts. These results suggest that the combination of heat treatment and gamma-irradiation might be more effective than only heat-treatment for improving the anti-diabetic activity of mistletoe extract and reducing its cytotoxicity.