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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.
정민상,곽동걸,최정규,박영직,김재원 한국방재학회 2015 한국방재학회 학술발표대회논문집 Vol.14 No.-
전기화재의 주요 요소는 전기아크와 스파크로 인한 것으로, 전기화재를 효과적으로 예방하려면 아크차단기(AFCI)의 설치를 법령으로 의무화 되어야 한다. 그러나 우리나라에서는 경제적인 이유와 합리적인 대안의 부재로 인해 현실적으로 어려운 실정으로 추진체계 또한 오랜 시간이 소요될 것으로 예상된다. 이에 대한 합리적인 대안으로 본 연구에서는 응답성과 신뢰성이 우수한 디지털 소자와 반도체 스위칭 소자 등을 이용하여, 선로전압을 상시 감지하고 일정 시간 내 아크나 스파크로 판단되는 이상 파형이 감지되면 화재의 징후로 인식하여 신속하게 전로를 차단하는 직력 아크사고의 감지시스템을 개발하고자 한다. 제안한 전기화재 보호장치는 제어방식이 간단하고 경량, 소형으로 제작이 가능하게 때문에 어디에서나 쉽게 적용이 가능한 장점이 주어진다.
노이즈 학습 알고리즘을 적용한 아크검출 장치에 관한 연구
곽동걸,정민상,백원종,류진규 대한전기학회 2023 전기학회논문지 Vol.72 No.10
It is very high that the proportion of fires caused by electrical factors in Korea. In particular, fires caused by arc faults account for most of the total electric fire. However, the prevention of arc faults is insufficient in Korea. Recently, arc detection devices have been developed to analyze the amplitude and frequency of arc_type noise signal. However, since these devices must count all noise signals or analyze frequency components in real time, harmless noise components similar to arc_type noise signals are also recognized as arc signals, resulting in malfunction and reliability degradation in arc fault detection. This paper proposes a new arc detection device to improve for the problems of existing arc detectors. The proposed arc detection device has an algorithm that periodically learns general non-risk noise generated in the customer's power environment, and then compares and analyzes it with the learned noise in the event of an arc fault. As a result, the proposed arc detection device ignores harmless noise components and detects only high-risk arc_type noise components, further enhancing the reliability and precision of arc detection. In addition, the proposed arc detection device verifies the validity of theoretical analysis and the practicality of the device through several actual measurements in various power environments.
한국과 일본 사무작업자에 대한 Type A 行動特性과 스트레스
孫銀一,鄭玟相 진주여자전문대학 1997 論文集 Vol.20 No.-
A Questionnaire was administered to the 1674 clerk workers who work in motor company in Korea and Japan. The questionnaire included the sociodemographic status working conditions. life habits, Type A behavior question, and stress and arousal check list. In general Koreans have marks in Type A behavior, and tend to have many marks in production department. However, Japanese tend to have many marks in purchasing department. Korean had lower scores in stress than Japanese. The important stressors were hope and goal in the future work environment in Korean, but in Japanese, were home life and job satisfaction.