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정민상,한은주,김영식,Jung, Min-Sang,Hahn, Eun-Joo,Kim, Yeong-Sik 한국의학물리학회 2007 의학물리 Vol.18 No.3
가로축 방식이 아닌 세로축 방식으로 초음파를 송수신하여 골밀도 측정을 하는 장치를 개발하였다. 반사된 초음파의 시간 차이를 이용하는 speed of sound (SOS) 방식은 주파수 차이를 비교하는 broadband ultrasound attenuation (BUA) 방식에 비하여 더욱 정확한 결과를 얻을 수 있다. 측정부위의 경우 엄지는 초음파 수신율이 좋으나 피부 두께의 변위가 많은 단점을 고려하여 중지를 채택하여 정확성을 높였다. SOS 방식만을 사용하여 측정한 결과 기존의 dual-energy x-ray absorptiometry (DEXA) 방식과 비교하여 거의 동일한 정확도를 얻을 수 있었다. An ultrasonic bone densitometer has been developed by measuring speed of sound signal transmitted and received on the skin, not through the horizontal axis but through the vertical one in tissue. The SOS(speed of sound) method measuring the time difference between the ultrasound signals reflected from the both sides of surface of bone could produce more precise result compared with the BUA(broadband ultrasound attenuation) method measuring the frequency difference. Middle finger is selected to be the best measurement position in order to increase the accuracy, after due consideration that the thickness of flesh at the down part of thumb shows too much variation although the ratio of the receiving signal is higher than the other fingers. The measured value by using SOS method shows almost the same result as compared with the conventional DEXA method.
태양광 발전설비의 전선로 접촉불량에 의한 전기아크 감지회로 토폴로지 설계
정민상(Min-Sang Jung),곽동걸(Dong-Kurl Kwak),최승민(Seung-Min Choi) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
Most electric fires in photovoltaic equipment are arisen from electric arc accidents, and these electric arcs are caused by momentary short circuit, the poor connection and contact of wiring, compression damage of line and, electrical breakdown. In this paper, to prevent electric fire, we propose a circuit topology that detects and controls electric arc accidents. The proposed circuit topology has an algorithm for detecting and amplifying only the arc component through a simple filter when an arc occurs and calculating the number of pulses of the arc. Some experimental results demonstrate the validity of the theoretical interpretation of the proposed arc detection circuit.
LED 가로등 누전사고 예방을 위한 전압형 절연저항 감지기 개발 및 IoT 시스템 구축
최승민(Seung-Min Choi),곽동걸(Dong-Kurl Kwak),류진규(Jin-Kyu Ryu),정민상(Min-Sang Jung) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
About 40% of outdoor earth leakage are caused by moisture penetration. Outdoor streetlights frequently have earth leakage. However, existing earth leakage breakers lack reliability. There is also a problem that it is difficult for managers to recognize earth leakage immediately. Therefore, this paper proposes a highly reliable earth leakage detector using a Wheatstone Bridge circuit. It also develops an IoT system that can be immediately recognized by managers in the event of a earth leakage.