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3-레벨 Hybrid ANPC 인버터의 양방향 운전 성능 분석
권봉현(Bong Hyun Kwon),김상훈(Sang-Hun Kim),배규철(Kyu-Chul Bae),이교범(Kyo-Beum Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.10
This paper analyzes the performance of a three-level hybrid active neutral-point clamped (ANPC) inverter in a bidirectional operation. In the bidirectional operation where electrical energy flows from dc source to ac grid and vice versa, a weakness of neutral-point-clamped (NPC) inverter is an unequal loss distribution between four silicon (Si) switching devices. A leg of the hybrid ANPC inverter consists of the four Si insulated gate bipolar transistors (IGBTs) and two silicon carbide (SiC) active switches. Only two SiC metal oxide semiconductor field effect transistors (MOSFETs) take all the switching events using redundant switching states but the switching losses are reduced compared to that of NPC inverter. The hybrid ANPC topology has an advantage of almost the same power loss operating as a grid-connected inverter and rectifier. The validity of the power loss analysis in the bidirectional operation is verified by a PSIM simulation model and experiment in the grid-connected three-phase three-level voltage source inverter.
마이크로 유체 원심분리기의 챔버 크기에 따른 회전 유동 가시화
전형진(Hyeong Jin Jeon),권봉현(Bong Hyun Kwon),김대일(Dae Il Kim),고정상(Jeung Sang Go) 한국가시화정보학회 2012 한국가시화정보학회지 Vol.10 No.3
This paper introduces a new parameter to design the 2×2 microfluidic centrifuge with single flow rotation positioned at the center of microchamber. The dimensional centrifugal acceleration momentum flux which is defined as the interfacial momentum flux divided by distance from the center of the chamber explains the flow rotation and its threshold provides a reference to expect single flow rotation. Through the numerical and experimental visualization of the flow rotation, the number and position of flow rotation in the 2×2 microfluidic centrifuge were examined. At a channel width of 50 μm and chamber width of 250 μm, single flow rotation was obtained over at a Reynolds number of 300, while at a channel width of 100 μm and chamber width of 500 μm, single flow rotation did not appear. The numerical analysis showed that the threshold centrifugal acceleration momentum flux to obtain single flow rotation was 3500 kg/m·s<SUP>2</SUP>.
마이크로 유체 원심분리기의 입구 조건과 챔버 크기에 따른 회전 유동 성능 평가
전형진(Hyeong Jin Jeon),권봉현(Bong Hyun Kwon),김대일(Dae Il Kim),김형훈(Hyung Hoon Kim),고정상(Jeung Sang Go) 한국가시화정보학회 2014 한국가시화정보학회지 Vol.12 No.1
This paper describes the measurement of performance evaluation of rotational flow varying chamber size and Reynolds number. Through the experimental visualization of the flow rotation, the number and position of flow rotation in the 2x2 microfluidic centrifuge were examined. At a chamber width of 250 ㎛, single flow rotation was obtained over at a Reynolds number of 300, while at a chamber width of 500 ㎛, single flow rotation did not appear. For performance evaluation, the intensity in microchamber was measured during 20 sec. At a chamber width of 250 ㎛, performance of rotational flow increased as Reynolds number increased. However, the variation of intensity in microchamber remained unchanged at a chamber width of 500 ㎛. The numerical analysis showed that the threshold centrifugal acceleration to obtain rotational flow for ejected particles was 200g.
온도장 가시화를 위한 연성회로기판을 이용한 온도센서 어레이 제작 및 성능평가
안철희(Cheol Hee Ahn),김형훈(Hyung Hoon Kim),차제명(Je Myung Cha),권봉현(Bong Hyun Kwon),하만영(Man Yeong Ha),박상후(Sang Hu Park),정지환(Ji Hwan Jeong),김귀순(Kui Soon Kim),조종래(Jong Rae Cho),손창민(Chang Min Son),이정호(Jung Ho L 한국가시화정보학회 2010 한국가시화정보학회지 Vol.7 No.2
This paper presents the fabrication and performance measurement of a temperature sensor array on a flexible substrate attachable to a curved surface using MEMS technology. Specifically, the fabrication uses the well-developed printed circuit board fabrication technology for complex electrode definition. The temperature sensor array are lifted off with a 10×10 matrix in a 50 ㎜×50 ㎜ to visualize temperature distribution. Copper is used as temperature sensing material to measure the change in resistances with temperature increase. In a thermal oven with temperature control, the temperature sensor array is characterized. The constant slope of resistance change is obtained and temperature distribution is measured from the relationship between resistance and temperature.