• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1663-1666
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• 2003

TMA clathrate that is used by PCM of ice storage system in this research creates hydrate crystallization at higher temperature than pure water, and application is expected as PCM because having comparative big dormant temperature without phase separation phenomenon. In case this research uses TMA clathrate by PCM, choose admixture by purpose to control or remove subcooling of TMA clathrate and evaluated experimentally. Subcooling is improved and can expect contraction of freezing machine running time and increase of coefficient of performance as that add admixture to TMA clathrate conclusively. Also, may supply thermal storage system that apply low temperature potential heat thermal storage material that subcooling is improved more extensively laying stress on medium size building and small size building, can expect allowance through localization of ice storage system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.16-23
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• 2020

An electric vehicle operates at high currents and requires real-time monitoring of the entire system for ensuring efficiency and safety of the vehicle. Current sensors are applied to drive the motors, inverters, and battery control systems, and are the key components to ensure constant monitoring of the magnitude and waveforms of the operating current. In this study, a heat treatment process condition to influence the performance of Permalloy current sensors was developed; the correlation between the output capacity, low-temperature characteristics, and high-temperature characteristics of the current sensor was studied; and the process was optimized to meet the required output accuracy and temperature characteristics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.70-76
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• 2004

High-temperature cylindrical sodium/stainless-steel heat pipes were manufactured and tested for transient as well as steady states. Total length of the heat pipe was 1 m and the diameter was 25.4 mm. Screen meshes of 3 different sizes were used to estimate the effect of mesh size on the thermal performance of the heat pipe. The minimum thermal resistance achieved was as low as 0.02$^{\circ}C$/W for the maximum thormal load of 2 ㎾. The average heat transfer coefficient in the evaporator was about 2,000 ㎾/$m^2$K and those in the condenser region were up to 5 times higher.

• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.122-129
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• 2003

The abilities and fading behaviors of 5 different inoculants were evaluated by the thermal analyses of the melts which were held at constant temperature after addition in induction furnace. The silicon content was preserved at the high holding temperature of 1,450${\sim}$1,500$^{\circ}C$, which reduced by oxidation at the low one. The inoculation temperature should be higher to obtain better and reproducible result. The inoculation performance of 1%Ba-Fe-Si was the best on the bases of effect and fading behavior.

• Ceramist
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• v.22 no.1
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• pp.96-106
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• 2019

Semiconducting carbon-based nanomaterials including single-walled carbon nanotubes(SWCNTs), multi-walled CNT(MWCNTs), graphene(GR), graphene oxide(GO), and reduced graphene oxide(RGO), are very promising sensing materials due to their large surface area, high conductivity, and ability to operate at room temperature. Despite of these advantages, the semiconducting carbon-based nanomaterials intrinsically possess crucial disadvantages compared with semiconducting metal oxide nanomaterials, such as relatively low gas response, irreversible recovery, and poor selectivity. Therefore, in this paper, we introduce a variety of strategies to overcome these disadvantages and investigate principle parameters to improve gas sensing performances.

• Solar Energy
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• v.18 no.3
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• pp.107-112
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• 1998

Basic design of a solar driven absorption cooling machine(SDACM) with a cooling capacity of 5 USRT was carried out. The SDACM is a single effect cycle driven by low temperature hot water from solar collectors. The SDACM design data were calculated by the steady state simulation program which was developed in this study The variation of COP and cooling capacity of the SDACM were investigated at different off-design conditions. Both the cooling capacity and the system COP were improved with decreasing cooling water temperature. If hot water temperature was increased, the cooling capacity was improved but the system COP was found to be decreased. The decrease of the system COP were basically caused by increased thermal loads in the system components.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.281-284
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• 2004

According to the National Space Program of Korea, KARI (Korea Aerospace Research Institute) has been developing a large space simulator (working dimension; $\Phi8m\;\times\;L10m$) to verify the performance of future large satellites under the space environment conditions. Especially, a very low temperature condition of space will be simulated by shrouds covering the inside surface of the vessel. The surface of shrouds will be cooled down to 17K by liquid nitrogen (LN2) from ambient temperature and hence, an optimal LN2 circulation system design is necessary to remove gaseous nitrogen (GN2) sufficiently and maintain the shrouds at the LN2 temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.964-970
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• 2006

Vapor compression refrigerators have much critical variables such as the controls of temperature and pressure switches, control durations and operating hours of electronic valves. This study compares and analyzes the data which is obtained from system controlling of the evaporation temperatures which are generally used in automatic pump down operating systems. Through this study, the automatic evaporation control operation system will be more ideal for the system to keep the proper temperature distribution depending on the purpose of evaporation side. The automatic pump down control operation is more appropriate for the system to aim at the effective use of evaporation side without using the temperature difference. And this test will be proved that the changes at the low pressure side didn't have significant impacts on the high pressure side.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2322-2327
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• 2008

This paper is to provide analysis model that can be used to investigate the improvement in energy efficiency for cooling tower by using fresh air. Numerical analysis of Air-cooled heat exchanger for single-phase flow with variations of outdoor air temperature has been performed. A complete set of correlations of the heat transfer in both refrigerant and air sides was employed for predicting the heat transfer rate. The numerical results derived from the correlations were verified with experimental results. The energy consumption for a hybrid cooling tower has been compared for variation of a outdoor air temperature. The results showed that the hybrid cooling tower in low outdoor temperature offers a significant improvement in energy efficiency. The thermal analysis aids significantly in the solution of the design problem of hybrid cooling tower.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.290-291
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• 2017

This study deals with an evaluation method for testing the robustness of the 4 kW commercial power electronic cooling system to the thermal environment. The power electronic cooling system consists of a cascaded push-pull DC / DC converter, a three-phase DC / AC inverter, and an electric compressor. The system manufactured by the thermal environment evaluation test (heat distribution test, thermal impact test, high temperature operation test, temperature cycle test, low temperature operation test) for the commercial electric power cooling system for commercial vehicle proves that it is robust against thermal environment.