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이미지 상관기법을 이용한 전자부품 페키지의 변형과 변형률 측정 기술
곽재복(Jae Bok Kwak) 한국자동차공학회 2018 한국자동차공학회 지부 학술대회 논문집 Vol.2018 No.5
Considering car electronics, various loading conditions such as elevated temperature with high humidity, and impact or random vibrations are applied. In this regard, development of advanced experimental techniques becomes important, because of conventional methods often are too limited to understand complexity of materials or structural behaviors of solid mechanics. This paper demonstrates two advanced experimental mechanics using digital image correlation (DIC) technology related to reliability of electronics package. DIC is a non-contact deformation measurement technique which uses gray intensity of images taken from any CCD cameras. First, strains and deformation behaviors were observed for interconnection of flip-chip package under thermal loading. Using microscopic DIC, full-field map of deformation and strain were obtained for 140um of solder interconnection. Second, transient dynamic deformation was also measured for printed board assembly (PBA) under shock impact loading. For this experiment, DIC was integrated with stereo-high-speed cameras to capture sequential images of PBA during drop event. These two experiments explains real behavior of deformation and strain for interconnection structures of electronics package under various loading conditions.
김주현,허연정,곽재복,안소희,오범조,이정식,이호영 대한질적연구학회 2023 대한질적연구학회지 Vol.8 No.2
Purpose: This study aims to not only understand the meaning and essence of patients’experiences visiting the Raphael Nanum Homeless Clinic but also explore what kind of healthcare programs they would like to have in the future by appraising patients’experiences in depth. Methods: This study employed a qualitative content analysis method. The data were collected from June 11, 2023, to June 25, 2023. A total of 17 patients who could provide detailed experiences of their visit to the Raphael Nanum homeless clinic participated in this study. We conducted a focus group interview with 6 patients and in-depth one-on-one interviews with the remaining 11 patients. Results: The qualitative content analysis result revealed five themes: “visiting a free clinic for various paths,” “positive experiences at the free clinic,” “negative experiences at the free clinic,” “dissatisfaction with the clinic site,” and “anticipation for the future of the free clinic.” Conclusion: To ensure the right to health and survival of marginalized populations in the future, it is necessary to establish comprehensive healthcare support measures, which include enhancing the facilities of the free clinic and expanding the range of available medical specialties.
Characterization of curing behavior of UV-curable LSR for LED embedded injection mold
태준성,임경규,이병옥,곽재복 한국유변학회 2016 Korea-Australia rheology journal Vol.28 No.4
For many applications, liquid silicone rubber (LSR) injection molding is widely used for their great design flexibility and high productivity. In particular, a sealing part for a mobile device such as smartphone and watch has been produced by injection molding. While thermally curable LSR causes deformation problem due to a high mold temperature, UV-curable LSR can be molded at room temperature, which has advantages for over-molding with inserts of temperature-sensitive materials. Ultraviolet light-emitting diodes (UV LEDs) have advantages such as a longer service life, a lower heat dissipation, and smaller size to equip into the mold than conventional halogen or mercury UV lamps. In this work, rheological behavior of UV-curable LSR during curing process was analyzed by UV LEDs available in the market. UV-LEDs of various wave lengths and intensities were tested. The steady shear test was applied to find the starting time of curing and the SAOS was applied to find the ending time of curing to estimate processing time. In addition, the hardness change with irradiation energy was compared with the rheological data to confirm the reliability of the rheological test.