• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1265-1268
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• 2009

In this paper, the effect of a flow barrier and bypass on the cooling performance for a straight fin heat sink is presented. Both side directions and upward direction of bypass are controlled using various ducts which have different width and heights. In addition, a flow barrier is used to control flow toward heat sink. Through experiments, the distance from leading edge of a heat sink to a flow barrier is varied for various bypasses under fixed volume flow rate condition. This study shows possibility to improve cooling performance when bypass and a flow barrier exist.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권3호
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• pp.122-126
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• 2004

The objective of this paper is to provide a comparison between the Line Start Permanent Magnet, Skeleton type Brushless DC, and the Snail-cam type Switched Reluctance Motor. These motors are compared under the same load characteristic as the cooling fan motor of a refrigerator. The comparison consists of speed, output power, efficiency, copper loss, and cost for three different motors. For the given application, the results provide an indication of the best machine suited with respect to performance and cost.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권4호
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• pp.217-224
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• 2005

The purpose of this study was to develop a cooler/heater using a thermoelectric module combined with a parallel flow type pulsating heat pipe with R-142b as a working fluid. The experiment was performed for 16 thermoelectric modules (6A/15V, size: $40\times40\times4mm$), varying design parameters of the heat pipe (inclination angle, working fluid charging ratio, etc.). Experimental results indicate that the optimum charging ratio and the inclination angle of the parallel flow type pulsating heat pipe were $30\%$ by volume and $30^{\circ}$, respectively. The maximum cooler/heater capacity were 479 W (COP: 0.47) and 630 W (COP: 0.9), respectively.

• The Transactions of the Korean Institute of Power Electronics
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• 제17권2호
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• pp.174-181
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• 2012

Energy storage system connected to the grid has two functions such as the surplus power of a grid is stored in batteries or the energy stored in batteries will supply to the grid when the grid needs. The battery energy storage system consist of power condition system (PCS) for power supply and battery conditioning system (BCS). Lithium-ion batteries are mainly used. In this paper, the battery energy storage system connected to the grid described. The configuration of the 2MVA class power control system using water cooling and battery system are presented. And control method for the system and the output filter design method are proposed. Experimental verification of the proposed system is provided with 2MVA PCS and 500kWh BCS.

• Proceedings of the KIEE Conference
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.24-25
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• 2006

In this paper, ZnO thin films were prepared on p-Si(100) by RF magnetron sputtering. Before the depostion, the substrates were pre-heated to 500, 400, 300, $200^{\circ}C$ or not. During the deposition, the substrates were cooled down naturally or kept and then the films were investigated by XRD(X-ray diffraction) and SEM (scanning micro scope). It is showed the most outstanding result that the film was prepared on the substrate were cooled from $400^{\circ}C$. When the substrate was cooled from a certain temperature during deposition, it could be improve the c-axis orientation and useful for application of SAW(surface acoustic wave) filter and FBAR(film bulk acoustic wave resonator) device.

• Proceedings of the KIPE Conference
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.391-392
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• 2017

최근 자동차 산업의 연구개발의 핵심화두는 효율성 제고 및 NVH(Noise, Vibration, Harshness) 개선에 있다. 특히나 많은 부품들의 개발에 있어서 운전자의 운전 편의성을 높이는 성능적인 지표 외에도 운전자가 느끼는 소음, 이상 진동에 대한 감성성능에 대한 소비자의요구도 높아지고 있다. 이러한 경향에 맞추어 자동차 각 부분의 소음저감, 효율향상을 고려한 설계에 대한 연구가 활발해지고 있다. 많은 자동차 부품들에 모터가 사용되고 있으며, 특히 차량용 쿨링팬의 경우 모터를 사용하여 차량 운행 시 발행하는 (배터리의 온도를) 적절한 수준으로 유지시켜주거나 친환경 자동자차 배터리를 쿨링 하는 역할을 한다. 대다수의 쿨링팬 모터로 BLDC모터가 많이 사용되며 이는 전통적인 제어 방법인 구형파제어를 사용하고 있다. 본 논문에서는 저전압 배터리의 전원을 사용하여 BLDC 쿨링팬을 안정적으로 구동할 수 있는 제어기를 개발하였고, 소음저감 및 높은 효율을 위하여 정현파로 제어하는 기법을 적용하였다. 개발된 시작품의 성능 시험을 통해 그 결과를 검증하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제34권2호
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• pp.179-184
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• 2010

This experimental study investigated the effect of tip clearance and bypass flow on the cooling performance of a straight fin heat sink. Both the horizontal and vertical directions of the bypass flow were studied by using a mass flow controller and test sections. The thermal resistance of a heat sink was obtained to elucidate the response of the cooling performance to tip clearance and bypass flow. The thermal resistance of a straight fin heat sink gradually increases with increasing tip clearance. A flow guide unit was employed to reduce the bypass flow. An optimal distance from the leading edge of the heat sink to the flow guide unit was found for the fixed volume flow rate. The contribution of the flow guide unit to the thermal performance of a heat sink increases with increasing volume flow rate.

• Journal of Magnetics
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• 제4권1호
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• pp.33-37
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• 1999

Unidirectional magnetic anisotropy field ($H_an$) was investigated for thin films of $CdCr{2-2x}In_{2X}Se_4 (0$\leq$x$\leq$0.2). This anisotropy originates from the microscopic anisotropic Dzyaloshinskii-Moriya (DM) interaction which arise from the spin-orbit scattering of the conduction electrons by the nonmagnetic impurities. This interaction maintains the remanent magnetization in the direction of the initial applied field. Then the single easy direction of the magnetization is parallel to the direction of the magnetic field. The anisotropy produced by field cooling is unidirectional I.e. the spins system deeps some memory of the cooling field direction. The chalcogenide spinel of$ CdCr_{2-2x}In){2X}Se_4$belongs to the class of the magnetic semiconductors. The magnetic disordered state is obtained when ferromagnetic structure is diluted by In. Then we have the mixed phase characterised by coexistence the magnetic long range ordering (IFN-infinite ferromagnetic network) and the spin glass order (Fc-finite clusters). The total magnetic anisotropy energy depends on the state of magnetic ordering. In our study we concentrated on the magnetic state with reentrant transition and spin glass state. The polycrystalline $ CdCr_{2-2x}In){2X}Se_4$ thin films were obtained by rf sputtering technique. We applied the ferromagnetic resonance (FMR) and M-H loop techniques for determining the temperature composition dependencies of Han. From the experimental data, we have found that Han decreases almost linearly when temperature is increased and in the low temperature is about three times bigger at SG state with comparison to the state with REE.

• The Transactions of the Korean Institute of Power Electronics
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• 제24권6호
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• pp.428-437
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• 2019

Analytical thermal models based on average convection heat transfer are frequently used for the design and selection of forced air-cooled plate fin heat sinks. In this paper, a convection heat transfer model within a ±10% margin of error was presented through experimental investigation. Five types of heat sinks with inlet widths of 1.7-6.8 mm were tested at 50-160 W heat sources to derive and verify the model. Causes of error between the experiment and analytical thermal model were analyzed and listed to design the heat sink. Using proposed method and the lists to be considered in the paper, a quick and accurate heat sink design of the power-conversion system is expected.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.38-38
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• 2007