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OSP 표면처리된 PCB 볼 패드용 CIELAB 색좌표 기반 검사 시스템
이한주,김창석,Lee, Han-Ju,Kim, Chang-Seok 한국마이크로전자및패키징학회 2015 마이크로전자 및 패키징학회지 Vol.22 No.1
본 연구에서는 OSP (organic solderability preservative) 표면처리된 PCB (printed circuit board) Cu 볼 패드의 변색을 검사하는 측정 시스템을 제안하였다. PCB 표면처리 중에서 OSP는 친환경적, 낮은 생산 비용 등의 장점으로 널리 이용되고 있으나 온도공정에 따른 변색이 발생하는 문제점이 있어서 접합 신뢰성 불량의 한 원인이 되고 있다. 이러한 변색 불량을 장치 비의존적 CIELAB 색좌표를 도입하여 분석하였다. 먼저, PCB 샘플을 검사하기 위해 적합한 측정 시스템을 표준 조명과 CCD 카메라를 이용하여 제작하고, 랩뷰 (labview) 프로그램을 이용하여 Cu 볼 패드의 변색을 검사하기 위한 이미지를 얻는 알고리즘을 제작하였다. 전체 PCB 이미지에서 이진화 (binarization) 및 외곽영역 추적 (edge detection) 영상처리 과정을 통하여 Cu 볼 패드만의 이미지를 획득하고, 장치 의존적인 RGB 색좌표에서 $3{\times}3$ 변환 행렬을 이용하여 CIELAB 색좌표로 변환하는 과정을 거친다. 본 측정 시스템을 이용하여 변색이 발생한 PCB 샘플을 분석한 결과 Cu 볼 패드 만의 이미지를 대상으로 분석하면 연산에 소요되는 시간이 감소하고 측정 시스템의 오인식률을 감소 시킬 수 있음을 실험적으로 증명하였다. 또한 CIELAB 색좌표 중 $L^*$ (밝음-어두움의 정도), $b^*$ (노랑-파랑의 정도)의 두 가지 기준의 조합이 Cu 볼 패드의 변색 검사에 적합한 색좌표로 분석되었다. We demonstrated an inspection system for detecting discoloration of PCB Cu ball pad with an OSP surface finish. Though the OSP surface finish has many advantages such as eco-friendly and low cost, however, it often shows a discoloration phenomenon due to a heating process. In this study, the discoloration was analyzed with device-independent CIELAB color space. First of all, the PCB samples were inspected with standard lamps and CCD camera. The measured data was processed with Labview program for detecting discoloration of Cu ball pad. From the original PCB sample image, the localized Cu ball pad image was selected to reduce the image size by the binarization and edge detection processes and it was also converted to device-independent CIELAB color space using $3{\times}3$ conversion matrix. Both acquisition time and false acceptance rate were significantly reduced with this proposed inspection system. In addition, $L^*$ and $b^*$ values of CIELAB color space were suitable for inspection of discoloration of Cu ball pad.
미세 수평 사각유로에서의 2상 유동 압력강하에 관한 실험적 연구
이한주,이상용,Lee, Han Ju,Lee, Sang Yong 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.5
Horizontal two-phase flow pressure drop within rectangular channels with small gap heights have been examined experimentally. The gap heights range from 0.4mm to 4mm corresponding to aspect ratios(the channel height divided by the width) from 0.02 to 0.2. Water and air were used as the test fluids with the superficial velocity ranges being 0.03-2.39m/s and 0.05-18.7m/s, respectively. The experimental results In rectangular channels were compared with the Lockhart-Martinelli correlation, which are widely used for conventional round tube. The Lockhart-Martinelli correlation turned out to be Inappropriate to represent the present experimental data. In this respect, considering the aspect ratio and gap-height effects, an empirical correlation on two-phase flow pressure drop was proposed. The proposed correlation successfully covers the bubbly, plug, slug and annular flow regimes.
이한주(Han Ju Lee),정동호(Dong Ho Jung),오승협(Seung Hyub Oh) 한국항공우주연구원 2011 항공우주기술 Vol.10 No.2
KSLV-I 상단 추진기관 시스템인 킥모터 시스템에 대한 형상 공차 기준을 설정하기 위해서는 임무 수행을 위한 초기 제어성 분석 결과를 바탕으로 각 하위 서브시스템에 대한 형상 공차를 부여하는 것이 필요하다. 본 논문에서는 킥모터 시스템의 형상 공차 기준과 지상시험용 및 비행시험용 모델에 대해 시스템 차원에서 수행된 형상 관리 결과에 대해 다룬다. We can acquire the criteria of configuration tolerance on the Kick Motor system, KSLV-I upper stage propulsion system from the analysis results of the initial controllability on the KSLV-I upper stage. Also we can assign configuration tolerances on each subsystem from the configuration tolerance on the Kick Motor system. This article deals with the Kick Motor system configuration tolerance criteria and the results of configuration management on the both ground test models and flight test ones.
청소년들의 피임실천율 및 피임방법(2007~2009년)
이한주 ( Han Ju Lee ),강희선 ( Hee Sun Kang ) 여성건강간호학회 2011 여성건강간호학회지 Vol.17 No.2
Purpose: This study was done to explore the rates and methods of contraception among Korean adolescents from 2007 to 2009. Methods: The study was a descriptive study. The data were taken from a web-based survey on risk behavior of Korean youth that was conducted between 2007 and 2009 by the Korea Centers for Disease Control and Prevention. Results: Among adolescents, 4.7% in 2007, 4.6% in 2008, and 4.7% in 2009 reported having had sexual intercourse. In those who had sexual experiences, less than 30% reported consistent use of contraception, whereas more than 45% report no contraceptive use at all. A condom was the most frequently used contraceptive method and its use has increased continuously among contraceptive users. Some of the adolescents were, nevertheless, using unreliable methods such as withdrawal or the rhythm method. Conclusion: The results of this study indicate that most adolescents are not using contraception consistently and some were relying on unreliable contraceptive methods. Efforts to raise awareness about consistent and correct contraceptive use and the importance of dual protection are essential.