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X-ray Microdiffraction 분석을 위한 CCD의 distortion 보정 방법
정진석 崇實大學校 生産技術硏究所 2001 論文集 Vol.31 No.-
X-ray microdiffraction analysis is a new technique in analyzing polycrystalline materials using polychromatic x-ray from synchrotron radiation sources. To collect multiple reflections at the same time, CCD detector is an essential equipment. For more accurate determination of lattice parameters, large area CCD must be used to collect as many reflections as possible. But the size of CCD chip is limited and tapered optical fiber bundle has been used to increase the x-ray sensitive area. The biggest problem in tapered optical fiber bundle - CCD system is the distortion coming from uneven pulling of the fiber bundle. In this paper, a method of correcting these distortion is suggested and errors in strain calculation due to the CCD distortion was estimated. The results from 5:1 tapered optics CCD suggest that the strain calculation can be done better than △d/d∼10^-4 accuracy.
FEM에 의한 차량전면부 사이드부재의 축방향 충격압궤 해석
차천석,정진오,양인영 한국안전학회 2003 한국안전학회지 Vol.18 No.4
The front-end side members of vehicles(spot welded hat and double hat shaped section members) absorb most of the impact energy in a case of front-end collision. In this paper, specimens with various spot weld pitches have been tested with a high impact velocity of 7.19m/sec(impact energy of 1034J). The axial impact collapse simulation on the sections has been carried out to review the collapse characteristics of these sections, using an explicit finite element code, LS-DYNA3D. Comparing the results with experiments, the simulation has been verified; the energy absorbing capacity is analyzed and an analysis method is suggested to obtain exact collapse loads and deformation collapse modes.
윤석찬,백승훈,정진태,한창수 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.5
This paper presents the study of the tension control in a web transfer system. In this study the sliding mode controller is applied to a time-varying nonlinear mathematical model. The model was derived to consider the effects of changing the roll rad;us in tension variation during winding and unwinding. The uncertainty in modeling may be due to unmodelled dynamics, on variations in system model. Designed sliding mode controller made the system error always staying in the suggested surface from the beginning. Through this, system is maintained to be robust against a disturbance and uncertainty. To verify the designed controller has a good performance, various inputs such as desired velocity, step input, and trapezoidal input are applied. When the sliding mode controller was used, the system(the tension control) performance was improved comparing to the PID controller. The robustness of the controller with respect to an estimation error was verified through simulations.
황성진,박혜림,김희석,김동철,김정헌 大韓成形外科學會 1994 Archives of Plastic Surgery Vol.21 No.2
Aplasia cutis congenita is a disorder of heterogeneous group characterized by isolate or multiple, localized or widespread areas of skin defect at birth. Since the first report by Cordon in 1767, it has been relatively rarely reported disorder abroad as well as domestically . It has several clinical subtypes classified by the location and pattern of skin absence, the presence of associated malformations and the mode of inheritance with unknown cause. We had a newborn male infant with this disorder clinically diagnosed, who showed wide full thickness skin defects on right knee and medial surface of ankle from birth, that covered with thin yellowish membrane and showed focal ulcerative area. On his familial history, there were four aplasia cutis congenita patients in the patient's mother in his maternal family side through four generations. Patient mother showed wide spread atrophic scarred looking appearance on her right lower leg. Chromosomal analysis revealed as normal male karyotype. The biopsy of lesions showed ulcerated surface and underlying chronic inflammation with total absence of epidermis. He had no associated congenital anomaly. The lesions healed rapidly for four weeks by conservative treatment as moist wound dressing and systemic antibiotic administrations. As a relatively uncommon skin anomaly, one case of aplasia cutis congenita is reported with review of references.