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정석영(S.Y. Jung),윤성준(S.J. Yoon) 한국전산유체공학회 2008 한국전산유체공학회 학술대회논문집 Vol.2008 No.-
For simulation of a wing unfolding motion for the various aerodynamic conditions, equation governing unfolding motion and moments applying to the unfolding wing were modelled. Aerodynamic roll moment consists of the static roll moment and the damping moment, which were obtained through wind tunnel tests and numerical analyses respectively. Panel method was used to compute the roll damping coefficient with twisted wing, whose deflection angle was equivalent to angle of attack due to the deployment motion. Roll damping coefficient is a function of angle of attack, sideslip angle, and deployment angle but not of angular velocity of deployment. Simulation with aerodynamic damping model gave more similar deployment time compared to wing deployment test results.
수술적 폐경과 자연 폐경에서 호르몬 보충요법 후 골반응의 차이
서유석(Y. S. Suh),박형무(H. M. Park),박선영(S. Y. Park),윤성준(S. J. Yoon),허민(M. Hur) 대한산부인과학회 1999 Obstetrics & Gynecology Science Vol.42 No.10
Objectives: surgical menopause, state of both oophorectomy, shows some different features compared to natural menopause. The purpose of this study was to compare effectiveness of hormone replacement therapy(HRT) in surgical menopause with it in natural menopause. Methods: bone mineral density was assessed in 71 surgically menopausal women at the time of starting HRT and was repeated after one year HRT. 28 were evaluated by quantitative computed tomography (QCT) and 43 were done by dual energy X ray absorptiometry (DXA). We divided the subjects into two groups according to the intervals between oophorectomy and the start of HRT(group 1: within 2 years after surgery, group 2: more than 2 years after surgery). Results: QCT-group 1 included 22 subjects, QCT-group 2 included 6. In group using DXA, 33 subjects were in group 1, and 10 in group 2. In natural menopause, 76 subjects were included and their bone mineral densities were assessed pre- and post-HRT(QCT: group 1, n=13, group 2, n=13, DXA: group 1, n=32, group 2, n=18) 1) Incidences of significantly decreased BMD in spite of HRT in surgically menopaused women were 59.0% in QCT-group 1, 60.6% in spine of DXA-group 1. These incidences are higher than those of natural menopause. 2) After 1 year estrogen replacement in surgical menopause, BMD decreased 6.86% by QCT and 1.15% by DEXA. But, surgical menopause women in group 1, BMD by QCT decreased 7.89%, spine BMD by DXA decreased 2.80%, femur neck BMD decreased 3.08%. Contrary to these results, BMD of natural menopause women increased 4.33%, 2.36%, and decreased 1.83%, respectively. Conclusion: Usual dosages of HRT cannot prevent acute bone loss effectively after both oophoectomized women. So, additional therapy will be prescribed to surgically menopaused women.
화학반응을 수반하는 극초음속 희박류 유동의 직접모사법 개발
정찬홍(C. H. Chung),윤성준(S. J. Yoon) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.3
A Direct simulation Monte-Carlo (DSMC) code is developed. which employs the Monte-Carlo statistical sampling technique to investigate hypersonic rarefied gas flows accompanying chemical reactions. The DSMC method is a numerical simulation technique for analyzing the Boltzmann equation by modeling a real gas flow using a representative set of molecules. Due to the limitations in computational requirements, the present method is applied to a flow around a simple two-dimensional object in exit velocity of 7.6 km/see at an altitude of 90 km. For the calculation of chemical reactions an air model with five species (O₂, N₂, O, N, NO) and 19 chemical reactions is employed. The simulated result showed various rarefaction effects in the hypersonic flow with chemical reactions.