• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.81-83
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• 2009

가정용 연료전지의 상용화를 위해서는 시스템의 신뢰성과 경제성 향상이 중요한 문제이며, 경제성 향상은 시스템의 가격 절감과 컨버터의 효율 향상을 통해서 달성될 수 있다. 본 논문은 1kW급 가정용 연료전지 시스템을 위한 새로운 고효율 푸쉬풀 컨버터의 토폴로지를 제안한다. 제안된 컨버터는 2차측을 낮은 정격 전압을 가진 정류 다이오드를 사용한 2단 정류구조로 구성하여 다이오드의 손실을 저감시키고, 다이오드의 접합 커패시턴스와 변압기의 누설 인덕턴스의 상호작용에 의해 발생하는 공진 전압의 크기를 저감시킴으로써 스너버에서 소모되는 전력을 줄여 효율을 향상시켰다. 실험에서는 일반적인 형태의 푸쉬풀 컨버터 1차측 회로와 고주파 변압기는 공유하고, 2차측회로만 변경하는 방법으로 효율을 측정하여 비교함으로써 제안된 방식의 우수함을 증명하였다. 제안된 방식의 푸쉬풀 컨버터는 기존방식에 비해 특히 경부하에서 높은 효율을 나타내었으며, 전 부하 구간에서 효율의 변화가 크지 않아 부하가변 방식의 운전에 유용하게 사용될 수 있을 것으로 판단된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.109-113
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• 2016

In this paper, we propose efficient LED lighting control algorithm using a David star magic square. Such algorithms increases the power reduction, the heat efficiency and LED life cycle and the efficiency of the LED lighting control consumption. Lighting system using existing Magic square algorithm could be reduced to increase the heat efficiency of the LED because the LED lighting time of the reduced cross-lighting. but it has a limit to the lighting control. If should apply the this proposed algorithm, can reduces power consumption and increases LED life-cycle, heat efficiency of LED lighting module and efficiency of the lighting control of the LED. This paper proposed that algorithm is by using a David star magic square on the LED Matrix. Divided into twelve areas to move the pattern in constant time interval, to perform the cross rotation and inversion techniques to thereby light up. In this paper proposed algorithm of this paper was compared with existing Magic square approach. As a result, power consumption and heat-value and luminous flux was reduced as the conventional lighting system. And, the LED lighting control increase the efficiency.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.1
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• pp.43-49
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• 2008

In this paper, a method using the Ant Colony Optimization(ACO) is proposed for reducing the power consumption of memory ECC checker circuitry which provide Single-Error Correcting and Double-Error Detecting(SEC-DED). The H-matrix which is used to generate SEC-DED codes is optimized to provide the minimum switching activity with little to no impact on area or delay using the symmetric property and degrees of freedom in constructing H-matrix of Hsiao codes. Experiments demonstrate that the proposed method can provide further reduction of power consumption compared with the previous works.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.409-415
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• 2016

In this study, we test the effects of the surface roughness on the hydro efficiency of double-suction centrifugal pumps ($Q=70.7m^3/min$, H = 87 m). The original surface of the impeller and inner casing were coated, resulting in surface-roughness reductions ranging from $100{\sim}110{\mu}m$ to $0{\sim}0.08{\mu}m$. We conducted experimental studies to measure the efficiency of the pumps and operating-pump electro energy variations with different surface roughness values. The experimental results showed that the efficiency of the pumps increased by about 0.8~1.79% and the electric energy of the operating pump was reduced by around 4.38 ~ 6.08%. These results indicate that the performance of the pumps depend largely on the surface roughness of the impeller and inner casing, and by reducing the surface roughness, we can improve the efficiency of the pump and reduce costs by reducing the electric energy consumption.

• Membrane Journal
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• v.29 no.6
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• pp.314-322
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• 2019

A worsened drought in Chungnam province of Korea due to climate change and increasing water demand at Daesan industrial complex have motivated the 100,000 ㎥/d seawater desalination project. In this study, therefore, the comprehensive analysis of parameters affecting the reverse osmosis (RO) performance was conducted. Under the various conditions of feedwater salinity and temperature in Daesan, energy consumption was calculated as 2.39 ± 0.13 kWh/㎥. The decrease in membrane flux and recovery rate positively impacted annual operation cost. The average total dissolved solids (TDS) of the permeate and energy consumption with highly permeable membrane according to the membrane manufacturer were 3.84 mg/L and 2.22 ± 0.13 kWh/㎥, respectively. In addition, energy saving up to 0.29 kWh/㎥ or cost reduction of membrane module up to 15.6% is expected by changing the RO configuration from full two pass to partial or split partial two pass.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.283-292
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• 2013

In order to ensure high performance, all the servers in an existing server cluster are always On regardless of number of real-time requests. They ensure QoS, but waste server power if some of them are idle. To save energy consumed by servers, the server power mode control was developed by shutdowning a server when a server is not needed. There are two types of server power mode control depending on when a server is actually turned off if the server is selected to be off: static or dynamic. In a static mode, the server power is actually turned off after a fixed time delay from the time of the server selection. In a dynamic mode, server power is actually turned off if all the services served in the server are done. This corresponds to a turn off after a variable time delay. The static mdoe has disadvantages. It takes much time to find an optimal shutdown time manually through repeated experiments. In this paper, we propose a dynamic shutdown method to overcome the disadvantages of static shutdown. The proposed method allows to guarantee user QoS with good power-saving because it automatically approaches an optimal shutdown time. We performed experiments using 30 PCs cluster. Experimental results show that the proposed dynamic shutdown method is almost same as the best static shutdown in terms of power saving, but better than the best static shutdown in terms of QoS.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.543-550
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• 2003

Thin paper proposes a new three-phase rectifier that actively shapes the input current sinusoidal by means of two rectifier bridges, each followed by a dc-dc boost converter. The proposed approach draws sinusoidal input current at unity power factor and has output voltage regulation capability The size and weight of magnetic material Is reduced by Incorporating a low KVA three-phase autotransformer and by directly connecting the dc outputs each other without using low frequency interphase transformer(IPT). The operation principle is described along with simple control method, and experimental results on a 1.5KW prototype are provided.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.823-829
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• 2013

IEEE 802.16 standard specifies the broadband wireless access (BWA) system including sleep mode to minimize the power consumption by a mobile station (MS). This paper outlines the overall operation of sleep mode and proposes a method to improve the power saving efficiency of the IEEE 802.16 sleep mode. The proposed method not only decreases the number of bytes that a MS in sleep mode needs to receive during listening interval but allows to indicate a control-specific operation such as periodic ranging.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2263-2264
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• 2008

전 세계적으로 에너지 소비가 지속적으로 증가하고 있는 가운데 석유, LNG와 같은 에너지 가격 또한 꾸준히 증가하고 있다. 이에 따라 에너지 절약을 유도하고 전력생산원가를 절감하고 전력수급의 안정을 도모하기 위한 수요관리가 대두되고 있다. 본 논문에서는 기존의 자료를 토대로 선형, 비선형 회귀분석을 실시하여 2015까지의 에너지 회피비용과 고효율 조명기기의 보급량을 추정한다. 그 후 에너지 회피비용의 변화를 고려하지 않은 현행 방식과 에너지 회피비용의 변화를 고려한 수정된 방식을 비교하여 경제성 평가에 대한 에너지회피비용의 영향에 대해 분석한다. 그리고 경제성 평가 결과를 통하여 고효율 조명기기 정책의 방향을 제시한다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.460-461
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• 2012

플라이백 컨버터는 SMPS의 전원회로 중 가장 많이 쓰이고 있는 컨버터이다. 최근 들어 원가 절감을 위한 Primary Side Regulation(이하 PSR)기술이 활발히 진행 중이다. 이 기술의 단점 중 하나는 직접적으로 제어하는 전압이 출력전압이 아니라 보조권선 전압이므로 변압기 커플링에 따라 실제출력전압에 약간의 오차가 생길 수도 있다는 것이다. 본 논문은 이를 감안하여 플라이백 컨버터의 트랜스포머를 기존의 방식들이 아닌 동축권선 방식을 적용하여 만듦으로써 보다 우수한 커플링으로 인해 출력전압의 오차가 거의 없음을 보여준다. 간단한 PSR의 원리에 대해 설명하고 커플링 계수를 비교한 후 UC3844를 이용한 Flyback converter를 이용하여 검증하였다.