• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.149-158
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• 2014

The effects of spot cooling on growing ever-bearing strawberry in hydroponic cultivation during summer by spot cooling system was estimated in plastic greenhouse located in Pyeongchang. The temperature of cooling water was controlled by heat pump and maintained at the range of $15{\sim}20^{\circ}C$. Cooling pipes were installed in root zone and very close to crown. Spot cooling effect was estimated by applying system in three cases which were cooling root zone, crown plus root zone, and crown only. White low density polyethylene pipe in nominal diameter of 16 mm was installed on crown spot, and Stainless steel flexible pipe in nominal diameter of 15A was installed in root zone. Crown and root zone cooling water circulation was continuously performed at flowrates of 300 ~ 600 L/hr all day long. Strawberry yields by test beds were surveyed from Aug. 1 to Sep. 30. The accumulated yield growth rate compared with a control bed of crown cooling bed was 25 % and that of crown plus root zone cooling bed was 25 % and that of root zone cooling bed was 20 %. The temperatures of root spot in root zone cooling was maintained at $18{\sim}23.0^{\circ}C$ and that of crown spot in crown cooling was maintained at $19{\sim}24^{\circ}C$. Also, the temperatures of root spot in crown plus root zone cooling bed was maintained at $17.0{\sim}22.0^{\circ}C$ and that of crown spot was maintained at $19{\sim}25^{\circ}C$.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.640-645
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• 2007

An experimental apparatus to show the hot spot cooling of an IC chip using a thermoelectric cooler is developed. The spot heating in very small area is achieved by the applying CO$_2$ laser source and temperatures are measured using miniature thermocouples. The active effects of thermoelectric cooler on the hot spot cooling system such as rapid heat spreading in the chip and lowering the peak temperature around the hot spot region are investigated. The experimental results are simulated numerically using the TAS program, which the performance characteristics such as Seebeck coefficient, electrical resistance and thermal conductivity of the thermoelectric cooler are searched by trial and error. Good agreements are obtained between numerical and experimental results if the appropriate performance data of the thermoelectric cooler are given.

• Journal of the Korean Ceramic Society
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• v.43 no.10 s.293
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• pp.619-625
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• 2006

The study was intended to investigate production tools and conditions of oil spot following calculating optimal composition of oil spot tenmoku glaze which can be produced at 1250$\sim$l260$^{\circ}C$. Since oil spot is influenced by the viscosity of glaze, viscosity of various glazes fit for oil spot production was determined by an SciGlass 6.0-based calculating method. Applied amount and calcinating conditions of the resulting substance of oil spot, $Fe_2O_3$, were analyzed. As a result, the viscosity of the glaze durable at 1260$^{\circ}C$ was found to range from 4.2 to 4.4, natural cooling was used after oxidizing calcinations at 1260$^{\circ}C$ for an hour, and the best oil spot tenmoku was produced by the natural cooling process after 1 h calcinations at 1150$^{\circ}C$ in the middle of natural cooling. Also, the study showed that thickness of glaze was found to have an effect on the production of oil spot and resulting oil spot was filled mostly with $Fe_2O_3$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.669-670
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• 2010

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.173-181
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• 1994

A Cold spot temperature control system for the batch annealing furnace has been estabilished in order to reduce energy consumption to improve productivity and stabilize the propertics of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, variation of coil cold spot temperature with time during heating and actual temperature measurements at mid-width of each coil during heating and actual temperature measurements at mid-width of each coil during soaking. The results of the tempaeature variation effect on the batch annealing are as follows. 1) Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas, and annealing cycle time is reduced to 2.7 times. 2) In case of short time healing, the slowest heating part is the center of B coil, in case of long time heating, the low temperature point moves from the center of coil to inside coil. And the temperature in this part is higher than other parts when cooling. When finished heating, the cold spot is located 1/3 of coil inside in case of HNx atmospheric gas. But center of coil in case of Ax atmospheric gas. 3) The outside of top coil is the highest temperature point when heating, which becomes the lowest temperature point when cooling. So, this point becomes high temperature zone at heating and low temperature zone at cooling, It has relation according to atmospheric gas component and flow rate. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1214mm width coil must be 2.5 hours longer than that of 914mm width coil for the same ciol weight. 5) Annealing cycle time with Ax atmospheric gas is extended 1 hour in of slow cooling during 5 hours in order to avoid rapid cooling.

• International Journal of Korean Welding Society
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• v.5 no.1
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• pp.35-43
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• 2005

This paper deals with the optimum condition for spot heating to correct the thin buckled panel caused by welding. Heat input models for each flame torch tip (500, 800, 2000) with standoff were establish using FEA to evaluate the temperature distribution of the heated plate and verified by experiment. With the heat input models developed for each torch tip, the effect of heating variables including ramp ratio(R) and standoff on the radial shrinkage and angular distortion was identified using FEA. Based on the results, the proper conditions of spot heating with air cooling were established. The amount and distribution of the radial shrinkage by spot heating were formulated as the function of heating variables and in-plane rigidity of the plate.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.1
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• pp.6-11
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• 2013

In this paper, the temperature characteristics of mold transformer for the distribution power system have been analyzed by using computational fluid dynamics(CFD). The model has been modeled by coil, cores, insulating materials and frames about 3MVA grade mold transformer and analyzed the temperature distribution of the structure with a heat fluid. The fluid, which is incompressible ideal gas, is analyzed as a turbulent flow phenomenon on the assumption that it is natural cooling of transformer cooling system. Through this study, by examining the temperature distribution and hot-spot of the structure field of the mold transformer, cooling design and temperature distribution information, which are demanded for designing are estimated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.511-512
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• 2013

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.195-202
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• 2010

Cooling air-conditioning of APC (Agricultural Products processing Center) workplace is important to improve the working environment in the summer season. As existing cooling systems for air-conditioning of whole workplace are inefficient because of their high equipment operating costs, relatively inexpensive cooling system is required. The objectives of this study were to simulate the thermal flow fields in APC workplace having the positive and negative pressure type fan and pad systems and spot cooling system by using CFD software (FLUENT, 6.2) and estimate the cooling effectiveness of respective cooling systems. The results showed that the negative pressure type fan and pad system was inappropriate for the present APC workplace because of excessive outside air influx from open gateway and the positive pressure type fan and pad system created relatively low temperature field but non-uniform velocity field at worker positions. The spot cooling system could supply cool air to worker positions with relatively constant air velocity and temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.883-884
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• 2010