• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.183-186
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• 2007

The injection molding process has high accuracy and good reproducibility that are essential for mass production at low cost. Conventional molding processes typically use the water-based mold heating and air cooling methods. However, in the nano injection molding processes, this semi-active mold temperature control results in the several defects such as air-flow mark, non-fill, sticking and tearing, etc. Therefore, in order to control temperature of the molds actively and improve the quality of the molded products, the novel nano injection molding system, which uses active heating and cooling method, has been introduced. By using the Peltier devices, the temperature of locally adiabatic molds can be controlled dramatically and the quality of the molded patterns can be improved.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.551-552
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• 2010

• 조명전기설비학회논문지
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• 제29권9호
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• pp.71-80
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• 2015

This paper proposes a convenient thermal modeling method for loss distribution control method of 3-level Active NPC(Neutral Point Clamped) inverter. In the drawback of conventional 3-level NPC, the generated losses can occur unbalance in each switching device, as a result, thermal utilization of designed system has been decreased. In order to compensate unbalanced losses, Active NPC inverter performed loss balancing control with thermal modeling during operation of each switching device. Therefore, this paper deals with a convenient thermal modeling method based on newton's law of cooling rather than conventional thermal modeling method. Both simulation and experimental results based on 10kW 3-level Active NPC inverter confirm the validity of the analysis performed in the study.

• 소성∙가공
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• 제17권5호
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• pp.337-342
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• 2008

The injection molding process has high accuracy and good reproducibility that are essential for mass production at low cost. Conventional molding processes typically use the water-based mold heating and air cooling methods. However, in the nano injection molding processes, this semi-active mold temperature control results in the several defects such as air-flow mark, non-fill, sticking and tearing, etc. In order to actively control temperature of the molds and effectively improve the quality of the molded products, the novel nano injection molding system, which uses active heating and cooling method, has been introduced. By using the Peltier devices, the temperature of locally adiabatic molds can be controlled dramatically and the quality of the molded patterns can be improved.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8140-8146
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• 2015

본 연구의 목적은 앰프 및 우퍼용 히트싱크가 장착된 400W급 자성유체 액티브 스피커의 방열성능 특성을 파악하기 위하여 엔클로저 내부의 온도 변화 특성을 실험적으로 고찰하였다. 이를 위하여 앰프 및 우퍼용 히트싱크를 설계하여 400W급 자성유체 액티브 스피커에 적용하였다. 결과적으로, 개발된 앰프 및 우퍼용 히트싱크가 장착된 400W급 자성유체 액티브 스피커의 방열성능은 개선되었고, 외기온도가 $25^{\circ}C$에서 $29^{\circ}C$로 증가함에 따라 스피커의 내부 온도는 상승하여 정상상태인 120 min경과 후 엔클로저 내부 온도는 $31.4^{\circ}C$에서 $33.2^{\circ}C$로 $1.8^{\circ}C$ 증가하였다. 또한, 본 연구에서 개발된 400W급 자성유체 액티브의 음압레벨은 기존의 액티브 스피커의 음압 레벨인 109.9 dB 보다 1.9 dB 향상된 111.8 dB로 우수하게 나타났다.

• 한국항공우주학회지
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• 제46권8호
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• pp.687-693
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• 2018

본 연구는 능동형 안테나 시스템의 안정적인 임무수행을 위하여 열적 신뢰성을 고려한 방열설계에 관한 연구이다. 능동형 안테나는 송수신부에 고성능의 고발열 소자들이 존재한다. 안테나의 성능 유지를 위해서는 방열설계를 통해 고발열 소자들에서 발생하는 열을 효과적으로 제거하고, 적정한 온도범위에서 동작할 수 있도록 하여야 한다. 능동형 안테나의 송수신부는 고발열부로 액체냉각을 이용한 방열이 효과적이다. 본 연구에서는 능동형 안테나의 열적 성능을 만족하기 위하여 액체냉각 시스템을 포함한 방열설계를 수행하였으며, 이를 수치해석을 통해 분석, 검증하였다.

• 전기학회논문지
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• 제59권9호
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• pp.1615-1620
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• 2010

A thin film thermoelectric cooler for COB direct assembly was proposed and the COB cooler structure was modeled by electrical equivalent circuit by using SPICE model of thermoelectric devices. The embedded cooler attached between the die chip and metal plate can offer the possibility of thin film active cooling for the COB direct assembly. We proposed a driving method of TEC by using pulse width modulation technique. The optimum power to the TEC is simulated by using a SPICE model of thermoelectric device and passive components representing thermal resistance and capacitance. The measured and simulated results offer the possibility of thin film active cooling for the COB direct assembly.

• 한국유체기계학회 논문집
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• 제17권6호
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• pp.84-88
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• 2014

A long term passive cooling system is considered as the most important safety feature for the nuclear design after the Fukushima Daiichi nuclear power plant accident in 2011. The conventional active pump driven safety systems are not available during a station Black Out (SBO) accident. The current design requirement on cooling time of the Passive Auxiliarly Feedwater System (PAFS) is about 8 hours only. To meet the 72 hours cooling time, the pool capacity of cooling water tank should be increased as much as 3~4 times larger than that of current water cooling tank. In order to extend the cooling time for 72 hours, a new passive air-water combined cooling system is proposed. This paper provides the feasibility of the combined passive air-water cooling system. The current pool capacity of water cooling system is preserved, and the cooling capability is extended by an additional air cooler.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.186-191
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• 2008

In this study, a room temperature AMRR (Active magnetic regenerative refrigerator) was fabricated, and experimentally investigated. Gadolinium (Gd) was selected as a magnetic refrigerant with Curie temperature of 293 K. Permanent magnet was utilized to magnetize and demagnetize the AMR. To produce large magnetic field above 1 T in the magnetic refrigeration space, a special arrangement of permanent magnets, so called Halbach array, is employed. Sixteen segments of the permanent magnets magnetized different direction, constitute a hollow cylindrical shaped permanent magnet. The AMR is reciprocated along the bore of the magnet array and produces cooling power. Helium is selected as the working fluid and a helium compressor is utilized to supply helium flow to the regenerator. The fabricated AMRR has different structure and compared to a convectional AMRR since it has an additional volume after the regenerator. Therefore, the cooling ability is generated not only by magnetocaloric effect of magnetic refrigerant but also by the pulse tube effect. It is verified that the cooling ability of AMR is increased due to the magnetocalric effect by the fact that the temperature span becomes $16^{\circ}C$ while the temperature span is only $8^{\circ}C$ when the magnetic field is not applied to the regenerator.

• 한국수소및신에너지학회논문집
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• 제18권3호
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• pp.292-300
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• 2007

A dynamic system model of a proton exchange membrane fuel cell(PEMFC) has been developed. The PEMFC of this study has large active area with water cooling in order to simulate the performance of the commercially viable PEMFC system for the transportation. A PEMFC stack model is a transient thermal model which is respond to the dynamic change of the coolant temperature and the flow rate. The dynamic cooling system model has been developed to determine the coolant flow rate and the coolant temperature. Prior to the system level study, thermal management criteria have been set up and brought to the control command of the cooling system. Since the system model is designed to evaluate the effect of thermal management on the system performance, it is attempted to determine the proper control algorithm of the cooling system so that the PEMFC system is working on the thermal management criteria. As a result of simulation, feedback controlled cooling system consumes less power and produce more power comparing with that of conventionally controlled cooling system.