• Journal of the Korean Society of Industry Convergence
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• v.11 no.2
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• pp.65-70
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• 2008

This study presents gas turbine cooling blade by using experimental and numerical works. The review cover researches related to cooling channels using finite element method in rotating blade. Also, the film cooling device and the heat transfer of the external surface of the blade are included. In addition, several methods to be used for the design of the blade, numerical method and experimental techniques are introduced. This work will contribute to improving the manufacturing of engine and the efficiency of gas turbine engines.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.23-27
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• 2008

This study is to evaluate the tool life of portable beveler which have various cooling system. It was compared with 3 different bevelers which has each other cooling system. Beveler A has no cooling system, beveler B has the cooling system for only inside of body, and beveler C has the cooling system for both the cutter and inside of body. The temperature of beveler A cutter surface had been continuously increasing as processing, but the rising tendency of temperature of beveler B cutter surface has slightly changed. In case of beveler C, the temperature is maintained. The tool life of beveler C is about 105m which is around 400% of beveler A(25m), and around 130% of beveler B(80m).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.430-435
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• 2009

The cooling stage greatly affects the product quality in the injection molding process. The cooling system that minimizes temperature variance in the product surface will improve the quality and the productivity of products. The cooling circuit optimization problem that was once solved by a response surface method with 4 design variables. It took too much time for the optimization as an industrial design tool. It is desirable to reduce the optimization time. Therefore, we tried the back-propagation algorithm of artificial neural network(BPN) to find an optimum solution in the cooling circuit design in this research. We tried various ways to select training points for the BPN. The same optimum solution was obtained by applying the BPN with reduced number of training points by the fractional factorial design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.357-360
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• 2009

The cooling stage greatly affects the product quality in the injection molding process. The cooling system that minimizes temperature variance in the product surface will improve the quality and the productivity of products. In this research, we tried the back-propagation algorithm of artificial neural network to find an optimum solution in the cooling system design of injection mold. The cooling system optimization problem that was once solved by a response surface method with 4 design variables was solved by applying the back-propagation algorithm, resulting in a solution with a sufficient accuracy. Furthermore the number of training points was much reduced by applying the fractional factorial design without losing solution accuracy.

• Journal of Institute of Convergence Technology
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• v.6 no.1
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• pp.37-41
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• 2016

The serpentine internal passage is located in turbine blade and it shows the variety heat transfer distribution. Especially, the Coriolis force, which is induced by blade rotation, makes different heat transfer distribution of the leading and trailing surfaces of serpentine internal passage. The different heat transfer is one of the reasons why the serpentine cooling passage shows low cooling performance in the rotating condition. So, this study tried to design the advanced the serpentine passage to consideration of the Coriolis force. The design concept of advanced serpentine cooling is maximizing cooling performance using the Coriolis force. So, the flow turns from leading surface to trailing surface in advanced serpentine passage to match the direction of Coriolis force and rotating force. We performed numerical analysis using CFX and compared the existing and advanced serpentine internal passage. This design change is induced the high heat transfer distribution of whole advanced serpentine internal passage surfaces.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.9-16
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• 2013

In this research, the effect of a heating system, which is powered by direct solar energy accumulated in phase change material (PCM) as heat storage material installed on the floor surface, on the cooling load was studied. Cooling load of a test building designed for this research was measured with fan coil unit and factors affecting it were also estimated. Experiments were performed with and without PCM installed on the building floor to understand the effect of the PCM on the cooling load. Additionally, to confirm the experiments results, the prediction calculation formula by average outside temperature and integrated solar radiation was composed using multivariate regression model. The results suggested that the heating system with PCM on the floor surface has the potential to shift electric power peak by radiating heat, stored during the daytime in it, at night, not increasing the total cooling load much.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.3
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• pp.171-178
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• 1992

The effect of nozzle characterristics on the mist-cooling heat transfer was investigated under the various flow conditions. Two different types of twin fluid nozzle were used, one is a $90^{\circ}$ angle tip nozzle with needle and the other is a $90^{\circ}$ angle tip non-needle nozzle. The cooling rate from the heated surface was measured and obtained the boiling curve as a function of surface temperature. An immersion sampling was employed for the measurement of droplet size of the spray. As a result of this experiment, the liquid sheet type nozzle shows better atomization when the mass ratio Mr>2.0, and collects more liquid droplets on the heated surface that results in better cooling effect. It was found that the maximum heat flux and heat transfer coefficient increased with increase in the volumetric flow rate, whereas the maximum heat flux decreased with increase in spray distance. The cooling effect depends upon the amount of collected droplet and droplet size, but it strongly depends upon the amount of collected droplet.

• Journal of Environmental Science International
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• v.27 no.12
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• pp.1261-1269
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• 2018

The purpose of this study was to investigate changes in the external thermal environment, following the application of evaporative cooling systems in buildings, in response to climate change. In order to verify changes in the external thermal environment, a T-test was performed on the microclimate, Thermal Comfort Index (TCI), and building surface temperature. Differences in microclimate, following the application of the evaporative cooling system in the building, were significant in terms of temperature and relative humidity. In particular, temperature decreased by more than 7% when the evaporative cooling system was applied. According to the results of the Thermal Comfort Index analysis, the Wet-Bulb Globe Temperature (WBGT) was below the limit of outdoor activities, indicating that outdoor activities were possible. The Universal Thermal Climate Index (UTCI) values were within the very strong heat stress range when the evaporative cooling system was not applied, When the system was applied, the UTCI values were within the strong heat stress range, indicating that they were lowered by one level. The building surface temperature decreased by ~10% or more when the evaporative cooling system was applied, compared to when it was not applied. Finally, the outside surface temperature of the building decreased by ~12% or more when the system was applied, compared to when it was not applied. We conclude that the energy saving effect of the building was significant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.25-32
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• 2005

Falling film heat transfer has been widely used in many applications in which heat and mass transfer occur simultaneously, such as evaporative coolers, cooling towers, absorption chillers, etc. In such cases, it is desirable that the falling film spreads widely on the surface forming thin liquid film to enlarge contact surface and to reduce the thermal resistance across the film and/or the flow resistance to the vapor stream over the film. In this work, the surface is treated to have thin porous layer on the surface. With this treatment, the liquid can be spread widely on the surface by the capillary force resulting from the porous structure. In addition to this, the liquid can be held within the porous structure to improve surface wettedness regardless of the surface inclination. The experiment on the evaporative cooling of an inclined surface has been conducted to verify the effectiveness of the surface treatment. It is measured that the evaporative heat transfer increases about $50\%$ by the porous layer treatment as compared with that from orignal bare surfaces.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.873-881
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• 2005

In this study, we made RFC, RCC and NCC according to the method by which polypropylene capillary tube was adopted, and evaluated cooling performance of each system through model experiments. We also investigated an applicability of the combined use of radiant cooling and dehumidification system. The results are as follows: In case of normal cooling load, RFC and RCC maintained set temperature without a condensation. But, in case of peak cooling load, RFC and RCC resulted in the lack of cooling performance and caused a condensation at the radiation surface. Consequently, the only use of polypropylene capillary tube is considered not to be enough for cooling in real application. Using the combination of a dehumidification and radiant cooling system maintained the set temperature without a condensation. NCC kept the set temperature at anytime without a condensation. It is more economic than packaged air-conditioner system due to the cooling effect of the floor surface.