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테이프 피더 내장 공압 액추에이터에 대한 신뢰성 평가에 관한 연구
최진화(Jin Hwa Choi),전병철(Byung Cheol Jeon),조명우(Myeong Woo Cho),강성민(Sung Min Kang),이수진(Soo Jin Lee) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.4
This research presents the reliability analysis of the pneumatic actuator within the tape feeder that is used to transfer the correct force to linked parts during 1.0E+7 cycles. First, the degradation analysis for thrust and air leakage is executed to obtain the failure data of a product based on its performance over time. Second, once the parameters has been calculated using the weibull 2-parameter distribution and MLE(Maximum Likelihood Estimation), information related to life such as reliability, failure rate, probability density function is estimated. Finally, MTTF(Mean Time To Failure) and B₁? life of actuators are calculated. MTTF means the mean life at the confidence level and B₁? life refers to the time by which 10% of the product would fail. In this study, failure causes and solutions are examined using the reliability analysis.
소아에서 발생한 Blastic Plasmacytoid Dendritic Cell Neoplasm 및 고찰
최진화 ( Jin Hwa Choi ),김병수 ( Byeong Su Kim ),송승현 ( Seung Hyun Sohng ),신동훈 ( Dong Hoon Shin ),최종수 ( Jong Soo Choi ) 대한피부과학회 2013 대한피부과학회지 Vol.51 No.12
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive hematopoietic malignancy which is derived from the precursors of plasmacytoid dendritic cells and is more infrequent in children than in adults. Formerly known as blastic NK-cell lymphoma or CD4+/CD56+ hematodermic neoplasm, the BPDCN is reclassified into the group of acute myeloid leukemia and related neoplasm by WHO in 2008. An 8-year old girl is being presented with bruise-like subcutaneous nodules with purpura on her right cheek from the performed biopsy. Histological examinations show sheet-like dense infiltrations of medium-sized lymphoid cells with irregular nuclei in the entire dermis. Immunohistochemical stainings of tumor cells were positive for CD4, CD56, LCA, TCL-1, TdT and focal positive for CD3, CD7, CD45RO and negative for CD20, CD30, CD34, EBV. The PET-CT scans indicate hot uptakes in the bone marrows which are suggestive of malignant infiltrations, and bone marrow biopsy findings are consistent with BPDCN of leukemic transformations. We present a rare case of BPDCN which affects the pediatric patient. (Korean J Dermatol 2013;51(12):970∼974)
비전정보와 캐드DB 매칭을 통한 웹 기반 금형 판별 시스템 개발
최진화(Jin Hwa Choi),전병철(Byung Cheol Jeon),조명우(Myeong Woo Cho) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.5
The target of this study is development of web based mold discrimination system by matching vision information with CAD database. The use of 2D vision image makes possible speedy mold discrimination from many databases. The image processing such as preprocessing, cleaning is done for obtaining vivid image with object information. The web-based system is a program which runs to exchange messages between a server and a client by making of ActiveX control and the result of mold discrimination is shown on web-browser. For effective feature classification and extraction, signature method is used to make sensible information from 2D data. As a result, the possibility of proposed system is shown as matching feature information from vision image with CAD database samples.
G-code 패킷 컨트롤을 통한 웹 기반 금형 가공 공정관리
최진화(Jin Hwa Choi),백세진(Se jin Baek),이정원(Jung Won Lee),전병철(Byung Cheol Jeon),조명우(Myeong Woo Cho) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-
This paper is proposed web-based mold manufacturing process management system for the effective manufacturing processing management. Developed system is G-code analysis to include manufacturing information and organize according to cutting level, tool species, and tool path, etc. It is able to insert OMM(On Machine Measurement)-code in the organized G-code. And this system is developed to control remote-place manufacturing process management system by web-based Sever / Client system. So this is able to control remote-place system monitoring and mold manufacturing process management.
리니어 타입 크로스 롤러 가이드 공압 액추에이터의 신뢰성 평가에 관한 연구
최진화(Jin Hwa Choi),신봉철(Bong Cheol Shin),조명우(Myeong Woo Cho),강성민(Sung Min Kang),이수진(Soo Jin Lee) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.5
This research presents the performance analysis of the linear type pneumatic actuators that are used in semi-conductor assembly line to transfer some product with high accuracy. To increase positioning and repetitive accuracies, a cross roller guide is implemented inside the pneumatic actuator. The finite element method is used to verify the force against working moments, and reliability analysis is performed to classify the breakdown cases. Also, reliability, failure rate, probability density function, and B₁? life are estimated under the boundary of thrust or air leakage conditions. In this study, the failure probabilistic function of the pneumatic actuators is analyzed using Weibull distribution.
캠-슬라이더 메커니즘 테이프 피더의 성능평가에 관한 연구
최진화(Jin Hwa Choi),전병철(Byung Cheol Jeon),조명우(Myeong Woo Cho),문찬영(Chan Young Moon),이수진(Soo Jin Lee) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.5
A tape feeder is an important feeding device to supply micro-chips such as 1005 and 0603 components to PCB in SMT process. Traditionally, tape feeding methods using sprocket wheel mechanism has been used for the pickup system of chip-mounters. However, there is growing needs for new feeding mechanism with high accuracy and confidence as electric components are getting much smaller. Thus, recently, a tape feeder using cam-slider mechanism is developed to meet such requirements. The major advantages of developed system are; significantly reduced indexing and backlash errors, slim and compact design, and improved repetitive capacity compared to existing system. In this paper, the performance evaluation criteria for the developed tape feeder are suggested. Stability against induced vibration, positioning accuracy, cycle time, durability and supply error rate are estimated using developed self testers. As a result, the excellence of developed tape feeding mechanism is validated using the effective rating methods.
악성 흑색종과 양성 멜라닌세포 모반에서 Ki-67/Melan-A 면역조직화학 이중염색의 발현양상
최진화 ( Jin Hwa Choi ),신동훈 ( Dong Hoon Shin ),최종수 ( Jong Soo Choi ),배영경 ( Young Kyung Bae ) 대한피부과학회 2014 대한피부과학회지 Vol.52 No.6
Departments of Dermatology, Pathology1, Yeung Nam University Hospital, Daegu, Korea Background: Melanomas need to be differentiated from benign melanocytic lesions during diagnosis. However, it is difficult to differentiate them using histopathology alone, since both neoplasms have broad morphological spectrums and subtle differentiating features. Objective: To evaluate the usefulness of Ki-67/Melan-A double staining for differentiating melanoma from benign melanocytic nevi. Methods: We selected 20 cases of intradermal nevi, 20 cases of compound nevi, 5 cases of dysplastic nevi, and 25 cases of melanoma from clinicopathologically proven cases reviewed by the Department of Dermatology at our medical center. Ki-67/Melan-A double staining was performed, and the Melan-A verified Ki-67 index (Ki-67-M index) and Ki-67 index were measured. The immunopositivity was measured in the deepest third of the lesions. Results: The Ki-67-M index of intradermal nevi, compound nevi, dysplastic nevi, and melanoma were 0.4±0.9%, 1.0±1.1%, 4.3±1.7%, and 24.1±10.9%, respectively. The best Ki-67/Melan-A cut-off point to distinguish melanomas from benign melanocytic nevi was 5%; the sensitivity and specificity were 100% and 97.7%, respectively. Immunopositivity in the deepest third of the intradermal nevi, compound nevi, and melanoma, were 10.5%, 20%, and 100%, respectively; the sensitivity and specificity for diagnosing melanoma were 100% and 84.6%, respectively. The sensitivity and specificity of combined Ki-67-M and immunopositivity in the deepest third for diagnosing melanoma were 100% and 97.7%, respectively. Conclusion: The Ki-67-M index and immunopositivity in the deepest third of melanoma were significantly higher than that of benign melanocytic nevi. Therefore, Ki-67/Melan-A double staining is a potentially valuable diagnostic tool for differentiating melanoma from benign melanocytic nevi. (Korean J Dermatol 2014;52(6):394∼401)
유족과의 면담을 통한 자살자 심리부검과 경찰 수사기록 조사를 통한 자살자 심리부검 결과 비교
최진화(Jin-Hwa Choi),이구상(Gu-Sang Lee),유혜림(Hye-Lim Yoo),서지혜(Jihye Seo),김은지(Eun Ji Kim),전홍진(Hong Jin Jeon) 대한신경정신의학회 2021 신경정신의학 Vol.60 No.1
Objectives This study compared the psychological autopsies of suicide victims through interviews of the bereaved family members and investigations of the police death records. Methods A psychological autopsy was performed using both the Korea Psychological Autopsy Checklist (K-PAC) through an interview of the bereaved family members and the Korea Psychological Autopsy Checklist for Police Record (K-PAC-PR) from the police death records at the same suicide victims. The frequency and percentage of each analysis item were checked, and the information collected was compared. Results Of 129 victims, information from two methods showed no significant differences in marital status, employment status, cohabitation status and relationship, location of suicide, method of suicide, and main cause. Among the stress information at the time of death, interpersonal and mental health problems were consistent, but the occupational, economy, family-related, physical health problems were estimated to have greater impact according to the interview methods. The estimates of depression, schizophrenia, bipolar disorder, and dementia were consistent, but the investigation method estimated more sleep disorders and anxiety disorders, and the interview methods estimated more drug use disorders. Conclusion Based on the analysis results, the two methods of a psychological autopsy should be properly utilized, and effective suicide prevention using the psychological autopsy information was discussed.