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Numerical analysis method to estimate thermal deformation of a ventilated disc for automotives
정원선,정성필,박태원 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.11
This paper presents an analysis method to estimate the thermal performance of a disc in a vehicle considering braking conditions and the characteristics of hydraulic devices such as the booster, master cylinder and proportional valve. The whole braking pressure transfer process in the hydraulic brake system from its generating by the pedal to action on the pad is analytically determined. The heat flux generated in the disc brake module is calculated by assuming that the braking energy changes into thermal energy. Heat flux is applied to the finite element disc model, and the temperature rise and deformation of a disc are estimated by performing the thermo-mechanical analysis. The analysis results are discussed and the analytical process and simulation model are verified.
녹내장 여과수술에서의 마이토마이신 결막하 주사 시기에 따른 여과포 형성의 실험적 연구
정원선,제승연,박성후,김진영,이상협,Weon Seon Jung,Seung Youn Jea,Sung Who Park,Jin Young Kim,Sang Hyup Lee 대한안과학회 2006 대한안과학회지 Vol.47 No.5
Purpose: To investigate the effects of varying the time of Mitomycin-C (MMC) subconjunctival injection before, during and after operation. Method: We divided rabbits into 3 groups according to injection time. Subconjunctival injections of 0.01% MMC 0.05 ml were given to the preoperative group at 6, 12 and 24 hours before operation, and to the postoperative group at 6, 12 and 24 hours after operation. The control group was given the injections during operation. Bleb formation and histologic analyses were studied for 4 weeks after operation. Results: For gross findings, the blebs of the preoperative and control groups were seen on the fourth day and completely formed at one week after operation, and were larger than those of the postoperative group. On the other hand, the blebs of the postoperative group were seen to have poor formation, displaying hypervascularity on the fourth day and disappearing one week after operation. For histologic findings, the proliferation of collagen fibers and the undifferentiation of fibroblasts observed in the preoperative and control groups were almost identical. But, the proliferation of collagen fibers and well-differentiated fibroblasts were seen to increase in the postoperative group, so aqueous flow was obstructed at week 3. Conclusions: Subconjunctival injections within 24 hours before or during glaucoma filtration surgery were better for bleb formation and preservation than those administerd after surgery.
정원선,이경진,강영근 (사)한국방사선산업학회 2022 방사선산업학회지 Vol.16 No.3
The experiment was conducted to minimize the methods and chemical procedures ofthe existing maritime specimen radiostrontium analytic method. Fish specimen among the maritimespecimens were selected, and extraction chromatography and carbonate extraction chromatographyamong the chemical separation stages were executed. 85Sr radioactive standard was used for themeasurement of the retrieval rate, and the retrieval rates of extraction chromatography and carbonateextraction chromatography were 85.3±0.7% and 95.0±1.7%, respectively. The verification of eachanalytic method was executed by using 90Sr radioactive standard. As the results of verification, bothextraction chromatography and carbonate extraction chromatography were found to be within ±5%of the corresponding standards. Time taken for preliminary processing, including the ashing time, foreach analytic method was approximately 2 days and 2 hours as well as 2 days and 6 hours for extractionchromatography and carbonate extraction chromatography, respectively. It is anticipated that it can beutilized as the rapid radiostrontium analytic method in the future since it is possible to reduce the timetaken for the analysis to approximately 1/5~1/6 of that for the fuming nitric acid method, and to executethe analysis of more specimens within a short period of time.
정원선,이창수,송현석,정도현 한국신뢰성학회 2011 한국신뢰성학회 학술대회논문집 Vol.2011 No.6
In this study, the analysis technique, which can estimate the temperature rise and thermal deformation of the ventilated disc considering the vehicle information, braking condition and properties of the disc and pad, is developed. The analytical process of the braking power generation during braking is mathematically derived. The thermal energy, which is applied to the surface of a disc as heat flux, is calculated. Then, the temperature rise and thermal deformation of a disc are estimated using FE software, SAMCEF. Shape of the cross section of the disc is optimized according to the response surface analysis method in order to minimize the temperature rise and thermal deformation. The hot judder analysis is done using the optimized disc, and the analysis results are discussed.
Flat-type 와이퍼 블레이드의 내구 신뢰성 향상을 위한 연구
정원선,서영교,김홍진,정도현 한국신뢰성학회 2011 한국신뢰성학회 학술대회논문집 Vol.2011 No.6
The windshield wiper consists of 4 parts: a blade, an arm, a linkage and a motor. The wiper blade makes contact with the windshield and is designed to be operated normally at an angle of 30 ~ 50 degrees to the front glass. If the contact pressure between the wiper blade and windshield surface is too high, noise and wear of the rubber will result. On the other hand, if the contact pressure is too low, the performance will do badly, since foreign substances such as dust and stains will not be removed well. The pressure and friction of the wiper blade has a great influence on its effectiveness in cleaning the front window. This is due to the contact of the rubber with the window. This paper presents the dynamic analysis method to estimate the performance of the flat type blade of the wiper system. The blade has a nonlinear characteristic since the rubber is an incompressible hyper-elastic and visco-elastic material. Thus, Structural dynamic analysis using a complex contact model for the blade is performed to find the characteristics of the blade. The flexible multi-body dynamic model is verified by the comparison between test and analysis result. Also, the optimization using the central composite design table is performed.