• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1850-1858
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• 2014

The object of this study is to develop an cooling control algorithm for electronics devices of the electric vehicle. In order to estimate the existing cooling control logic of the electronic devices for the small and medium sized electric vehicle, the experiments on the coolant temperature variation of the cooling system were conducted under 4 different seasons conditions. As a result, the existing cooling control logic were overcooled when it was compared with the reference temperature for a required cooling load. In addition, the newly developed optimum cooling control logic for improving the mileages of the tested electric vehicle with consideration of the ambient temperature, vehicle speed, and refrigerant temperature of the air conditioning on/off is necessary.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.298-303
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• 2002

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. In order to investigate the effect of blowing ratios on the film cooling of turbine blade, cylindrical body model was used. Mainstream Reynolds number based on the cylinder diameter was $7.1{\times}10^4$. The effect of coolant flow rates was studied for blowing ratios of 0.7, 0.9, 1.2 and 1.5, respectively. The temperature distribution of the cylindrical model surface is visualized by infrared thermography (IRT). Results show that the film-cooling performance could be significantly improved by the shaped injection holes. For higher blowing ratio, the spanwise-diffused injection holes are better due to the lower momentum flux away from the wall plane at the hole exit.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.969-974
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• 2002

Thermal characteristics according to the cooling methods are studied for the three type spindles with high frequency motor. For the analysis, three dimensional mode]s are built considering heat transfer characteristics such as natural and force convection coefficients. Unsteady-state temperature distributions and thermal deformations according to the cooling conditions are analyzed by using the finite element method.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.104-111
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• 2011

To protect the turbine blade, many cooling techniques has developed. With all other things, film-cooling has been widely used as the important alternative. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as cylindrical, crescent, louver, and dumbbell holes. To analyze the turbulent flow and the film-cooling mechanism, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been assessed in comparison with experimental data. The characteristics of fluid flow and the film-cooling performance for each shaped hole have been investigated and evaluated in terms of centerline, laterally averaged and spatially averaged film-cooling effectivenesses. The dumbbell shaped hole shows better film-cooling effectiveness than other shaped holes. And the louver and cylindrical shaped hole shows lower one, and concentrated flow on centerline only.

• Journal of Biosystems Engineering
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• v.24 no.1
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• pp.31-40
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• 1999

The objective of this study were to develop a cooling simulation model for fixed-bed of rough rice and to analyze the factors affecting cooling time of rough rice. A computer simulation model based on equilibrium conditions between grain and air was developed to predict temperature and moisture content changes during cooling of rough rice. the result of t-test showed that there were no significant differences between predicted and measured temperature changes on significance model agreed well with measured values. This cooling simulation model was applied to analyze the effect of some factors, such as air flow rate, cooling air temperature and humidity, initial grain temperature and moisture content, and bed depth, on cooling time of rough rice. Cooling rate increased with increase of air flow rate and bed depth whereas it decreased with increase of cooling air temperature and humidity and initial grain temperature. Among these factors, the most important factor was air flow rate. Specific air flow rate of 0.35㎥/min㎥ was required for cooling rough rice in 24 hours.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.34-41
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• 2001

A study has been conducted to observe the slot film cooling effect on a convergent nozzle wall. The slot film cooling is used to protect the nozzle wall from the hot combusted gas by the coolant injected from the slot around the inner wall of the nozzle. The film cooling effectiveness and the heat transfer to the nozzle wall are influenced significantly by the blowing ratio of the coolant to the main flow and those are also influenced by the shape of the slot and the flow acceleration in the nozzle. In the present study, the heat transfer for the various blowing ratios has been performed by the experimental method and the results are compared with the results computed by the empirical formula. The numerical method has been conducted to compare the film cooling effectiveness of the convergent nozzle with that of the cylinder. For the relatively low blowing ratio, the cooling effectiveness increases sharply as the blowing ratio increases, and the increasing rate slows down for the high blowing ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.37-46
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• 2012

The calculation model for heat transfer analysis of rocket engine combustion chamber considering film-cooling has been established. Convective, radiative heat transfers and film-cooling effect in combustion chamber were evaluated using empirical equations especially for rocket engine combustors, and for heat transfer outward from chamber wall general convective and radiative equations were applied. Structural grid has been generated inside chamber wall for FVM calculations, and transient thermal analyses were carried out by time-marching techniques. LOx/kerosene rocket engine with chamber pressure of 50 bar has been analysed, and it is shown that, in that case, the film-cooling less than 4% remarkably contributes to reduce wall temperature, but the effect of the effect of film-cooling more than about 4% is not significantly increased.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.93-99
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• 2006

The effects of the changes of a film cooling mass flow rate and operating conditions on wall heat flux characteristics of a subscale calorimetric combustion chamber were investigated by experiment and numerical analysis. At the nominal operating condition, with the film cooling mass flow rate being 10.5 percent of a main fuel mass flow rate, maximum heat flux at the nozzle throat was measured to be 30 percent lower than that without the film cooling. For the relatively higher mixture ratio and chamber pressure condition, maximum heat flux at the nozzle throat was increased by 31 percent compared to that of the nominal condition test without film cooling.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.756-762
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• 2011

A gas deflector cooling system plays an important role in the suppression of shock wave generated during the ignition of a launch vehicle engine. Also, this system decrease a large vibration of damaging the payload and structure of the launch vehicle. The gas deflector cooling system in the launch pad of NARO space center was constructed to directly inject water into the plume of the launch vehicle engine. The flight test result of NARO space launch vehicle showed that this method had a good performance on the viewpoint of cooling the gas deflector.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.315-320
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• 2008

This experimental study has been conducted to investigate the effect of the flame holder on the multi-slot film cooling in the ramjet combustor. The turbulent wake which is generated by the flame holder on the entrance of the coolant flow path affects on the slot. Adiabatic film cooling effectiveness on the downstream wall of the slot exit are measured. The results show that the film cooling performance is rapidly decreased after the slot exit by shear layer and high turbulence intensity between separated flows and coolant flows.