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LⅡ를 이용한 디젤 엔진 배기에서의 PM 일차 입자 크기 계측에 관한 연구
전홍식(Hongsik Chun),박종일(Jongil Park),김희준(Huijun Kim),류훈철(Hoonchul Ryu),한재원(Jaewon Hahn),전광민(Kwang Min Chun) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Recently particulate matter (PM) emission regulations are becoming more strict for diesel engines. There is increasing interest for measuring not only concentration but also size of the particles. Laser-induced incandescence (LⅡ) has emerged as a promising technique for measuring particle volume traction and size. In this study, the Simple TIRE-LⅡ(Simple Time Resolved-LⅡ) method was applied to diesel engine exhaust for measuring PM primary particle size. The panicle size data from LⅡ technique were calibrated using Transmission Electron Microscope (TEM) photographs. In diesel engine experiments for particle size measurement, results from LⅡ measurement are in a good agreement with those from TEM photograph, and difference between two measurements was less than 16%.
레이저 유도 플라즈마 분광분석법을 이용한 연성회로기판 절단 공정에서의 탄화 특성 계측
류훈철(Hoonchul Ryoo),이형우(Hyungwoo Lee),오창훈(Changhoon Oh),한재원(Jaewon Hahn) 한국레이저가공학회 2008 한국레이저가공학회 학술대회 논문집 Vol.2008 No.-
In the present study, the carbon contamination generating from the laser based cutting process of flexible printed circuit board (FPCB) is characterized by molecular spectrum emission of carbon using the technique of laser induced breakdown spectroscopy (LIBS). Using KrF excimer laser the spectrum emission of polyimide film ranging from 250 nm to 700 nm is analysed and from the result, the dominant spectrum emission of carbon contamination is identified by the C₂swan band. The total emission area of C₂swan band ranging from 500 nm to 517 nm is compared according to the laser repetition rate. Increasing the repetition rate, the integrated emission area has a tendency to decrease exponentially. When the energy per pulse of the laser decreases as 74% in comparisin between 20 Hz and 150 Hz operation condition of repetition rate, the integrated emission area decreases rapidly as 15 %. The result shows that in the cutting process of FPCB using UV laser, the reduction of pulse energy has a strong influence on the generation of carbon contamination.
PID 제어기법을 이용한 펄스 레이저 출력 안정화에 관한 연구
류훈철(Hoonchul Ryoo),곽승우(Seungwoo Kwak),강동원(Dongwon Kang),김경식(Kyoungsik Kim),한재원(Jaewon Hahn) 한국레이저가공학회 2006 한국레이저가공학회지 Vol.9 No.2
In this study, PID control method was applied to decrease the power fluctuation of the pulse laser which is one of the major processing variables in laser machining process. To stabilize the power fluctuation of the pulse laser, we averaged 10 pulse outputs of Nd:YAG laser operating in 10Hz using boxcar averager, and with taking this averaged output as an input signal, we conducted PID control using optical attenuator which is consisted of half wave plate attached on the stepping motor and polarizer. When PID control was not enabled, the power fluctuation was 4.71% and with PID control, the power fluctuation was 1.86% for 2 hours and 1 hour respectively. As a result, we stabilized the power fluctuation of the pulse laser by 60.5%