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- 저자 : 최한올 ( Choi Han-ol ) (검색결과 3 건)
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스위칭 잡음의 시간 특성 분석을 통한 주파수 특성 예측
최한올(Han-Ol Choi),유승렬(Seung-Real Ryu),김은하(Eun-Ha Kim),박동철(Dong-Chul Park),이재현(Jae-Hyun Lee) 한국전자파학회 2012 한국전자파학회논문지 Vol.23 No.5
하이브리드 전기 차량 내에 존재하는 DC-DC 컨버터 또는 DC-AC 인버터에 의해 스위칭 잡음이 발생된다. 이 스위칭 잡음은 컨버터 또는 인버터의 스위칭 회로 내에 존재하는 전력 다이오드의 역 회복 동작에 의해 발생된다. 다이오드의 반전 시간과 역 회복 시간이 역 회복 구간의 모양을 결정한다. 본 논문은 스위칭 잡음의 주파수 스펙트럼을 다이오드 역 회복 구간의 모양을 통해 예측하고, 측정 결과와 비교하여 주요 주파수 구간이 다이오드의 반전 시간과 직접적인 연관이 있다는 것을 확인하였다. DC-DC converter and DC-AC inverter in a hybrid electric vehicle (HEV) generate the switching noise. It may be generated by the reverse recovery operation of the power diode in the switching circuit of the converter or the inverter. The shape of the reverse recovery region may be determined by both reverse time and recovery time in the diode. So, in this paper, the frequency spectrum of switching noise was estimated by the shape of the reverse recovery region and compared with the measured results. It shows that the meaningful region of the frequency spectrum is directly related with the reverse time.
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최한올 ( Choi Han-ol ),홍후조 ( Hong Hoo-jo ) 부산대학교 과학교육연구소 2018 교사교육연구 Vol.57 No.1
The purpose of the study was to analyze factors affecting elementary school teachers’ intentions for using MOOC specifically in regards to UTAUT2 (Extending the Unified Theory of Acceptance and Use of Technology). Two hundred and eleven elementary school teachers participated in an online survey and the results were analyzed by using a hierarchical regression. The factors included in the study were performance expectancy, effort expectancy, social influence, facilitating conditions in UTAUT (Unified Theory of Acceptance and Use of Technology), hedonic motivation, price value in UTAUT2 and trust. The study results indicated the followings. First, gender, career, and academic background were not significant factors influencing elementary school teachers’ intentions to use MOOC. Second, in hierarchical regression model 2, social influence and performance expectancy had significant effects on teachers’ intention to use MOOC. Third, hedonic motivation, social influence, and price value showed a positive association as influential factors for elementary school teachers to use MOOC in hierarchical regression model 3. Finally, in the last hierarchical regression model, hedonic motivation, social influence, and trust were influential factors for elementary school teachers to use MOOC. The variables effort expectancy and facilitating conditions, however, were not influential factors for elementary school teachers to use MOOC. In the study, a majority of teachers responded positively to using MOOC and therefore education authorities should actively introduce MOOC to teachers and try to find ways to connect MOOC to teacher training programs.
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박재홍(Jae-Hong Park),정규원(Gyu-Won Jeong),유승렬(Seung-Ryul Ryu),김은하(Eun-Ha Kim),최한올(Han-Ol Choi),이재현(Jae-Hyun Lee) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.9
본 논문은 분해능이 향상된 인덕티브 방식 토크 센서의 새로운 구조를 제안한다. 토크 센서의 결합 구조와 수신 코일의 감김 수를 변화시켜 분해능을 증가시켰다. 이 토크 센서는 비접촉식으로 마모가 없기 때문에 내구성이 높으며, 진동이나 기구의 비틀림 등에 의한 편차가 적고, EMC(Electromagnetic Compatibility) 및 온도 특성이 우수하다. In this paper, a new structure to improve the resolution of an inductive torque sensor is proposed. The new coupling structure and the change of number of turns for the receiving coil increase the resolution of the torque sensor. Because this torque sensor has non-contact points, it has no abrasion at the contact point, and is very durable. Also, the torque sensor has less variation due to vibration or strain, and it has a good EMC(Electromagnetic Compatibility) and thermal characteristics.
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