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방혜진,조종두 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
Composite materials are composed of multiple types of materials as reinforcement and matrix. Among them, CFRP (Carbon fiber reinforced polymer) is widely used materials in automotive and defense industry. Carbon fibers are used as a reinforcement, of which Young's modulus is in a prepreg form. In automotive industry, especially, high strain rate test is needed to measure dynamic properties, used in dynamic analysis like high inertia included simulation as a car crash. In this paper, a SHTB (Split Hopkinson tensile bar) machine is employed for estimating stress-strain curve under dynamic load condition on aluminum 6061 and CFRP. The strain rate range is about from 100 /s to 1000 /s and the number of prepreg layers of composite specimen is total eight plies which are stacked symmetrically to structure CFRP. As a result, stress / strain point data are obtained and used for simulation into stacked composites.
배지조성에 따른 포플라 Callus의 Anthocyanin 생산
방혜진,이승우,최근원,정인식,설일환 慶熙大學校 1997 論文集 Vol.26 No.-
Studies were carried out to investigate the effect of cultural media on callus growth and anthocyanin production using the callus derived from the leaf discs of the Populus hybrid (Populusnigra × Populus maximowiczii cv. Yanghwangchul). Callus growth was the best in SH medium supplemented with 30 g·liter^-1 sucrose whereas anthocyanin production was maximum in White medium. But the amount of anthocyanin biosynthesis per vessel was the best in SH medium. Callus growth was similar in SH medium containing sucrose, fructose of glucose, but anthocyanin biosynthesis was enhanced in SH medium containing sucrose. Sucrose concentrations of 3.5% was the best for both callus growth and total amount of anthocyanin biosynthesis per vessel. Maltose suppressed both callus growth and anthocyanin biosynthesis. Callus growth was enhanced by higher concentrations(2X) of KNO_3 and CuSO_4, and by standard concentrations(1X) of CaCl_2 and H_3BO_3 in the medium. Total amount of anthocyanin biosynthesis was, however, somewhat different from the pattern of salts effects on callus growth.
CMP용 로터리 유니온 씰 유닛의 수명보증을 위한 신뢰성 연구
방혜진,박종원,최종식,안수봉,이희장 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.12
The life and environmental resistances of a rotary union, which is a sealing device that ensures fluids do not mix when supplying multiple fluids during the semiconductor CMP process, are determined in this study. During the CMP process, the rotary union presses and polishes the wafer by applying pressure, and lifts and transports the wafer by creating a vacuum. The rotary union used in this study employs a non-lubricating fluid-based sealing method and does not require a lubricant supply device; thus, it is advantageous in semiconductors and display equipment that are sensitive to lubricant contamination. Based on the analysis, life assurance and reliability evaluations are necessary for products with repeated use. Before the life test, finite element analysis is performed using a CAE program; and using pressure as a variable, the rated pressure is set, and the Von-mises stress values of the main shaft and seal unit are obtained. Subsequently, a jig for the life test is manufactured, and the accelerated life test time corresponding to the warranty time is calculated and tested. Additionally, the reliability of the product is verified through an environmental resistance test. 본 논문에서는 반도체 CMP 공정에서 여러 유체를 공급할 때 서로 섞이지 않도록 유체 공급을 유지하는 밀폐장치인 로터리 유니온의 수명 및 내환경성 시험을 하였다. 로터리 유니온은 CMP 공정에서 압력을 가하여 웨이퍼를 눌러 연마 작업을 하고, 진공을 걸어 웨이퍼를 들어 올리며 이송하는 역할을 한다. 본 논문에서 사용된 로터리 유니온은 무윤활 밀폐방식으로 윤활유 공급장치가 필요 없어 윤활유 오염에 예민한 반도체 및 디스플레이 장비에 강점을 가지고 있다. 반복 작업을 하는 해당 제품에 대해 수명 보증 및 신뢰성평가가 필요하다고 판단하였으며, 수명시험 전, CAE 프로그램을 이용한 유한요소 해석을 진행하였다. 압력을 변수로 하여 정격 압력이 포함되는 범위를 설정하여 축과 씰 유닛의 조합응력값을 확인하였다. 수명시험을 위한 지그를 제작하여 보증시간에 상응하는 가속수명시험 시간을 계산하여 시험하였고, 내환경성 시험을 추가로 수행하여 해당 제품의 신뢰성을 확보하였다.
Study on crack propagation of adhesively bonded DCB for aluminum foam using energy release rate
방혜진,이상교,조종두,조재웅 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1
Aluminum foam with initial crack, which has a closed cell form adhesively bonded, is studied to compare and analyze the crackpropagation behavior by using both experimental and finite element analysis techniques. The specimen is loaded in Mode I type of fractureas 15 mm/min speed of a displacement control method. The experimental results were used to accommodate the finite elementanalysis performed with commercial software ABAQUS 6.10. First, using a video recording, five steps of experiment were selected atrandom and then the energy release rate was calculated. The estimated energy release rate was then used as fracture energy into the finiteelement analysis. Comparing the experimental axial load-displacement graphs and the finite element analysis results, roughly equivalentpeak values were observed in the cohesive strength of the aluminum foam double cantilever beam. However, force versus displacementpatterns showed somewhat different: little deformation was observed in aluminum foam, whereas adhesive parts in double cantileverbeam were significantly deformed.