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특성곡선 해법 설계 극초음속 노즐의 경계층 보정 및 레이놀즈 수 효과
김소연(S.-Y. Kim),최정열(J.-Y. Choi),김성돈(S.-D. Kim),정인석(I.-S. Jeung),이종국(J.-K. Lee) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5
특성곡선 해법을 이용하여 출구 마하수가 6과 7인 극초음속 풍동의 노즐을 설계하였다. 설계된 노즐에 대하여 마하6에서는 4×104에서 4×107, 마하 7에서 4.6×104에서 4.6×106 범위의 레이놀즈수에서 전산유체역학 해석을 통한 경계층 예측을 수행하였다. 해석 결과로부터 경계층 속도가 벽면 위 최대 속도의 95%되는 두께를 선택하여 노즐 형상을 보정하였다. 점성 유동 해석을 다시 수행하여 보정 결과를 확인한 결과, 보정된 노즐은 설계 마하수를 잘 만족함을 확인할 수 있었다. Hypersonic wind tunnel nozzles are designed by the method of characteristics for exit Mach number 6 and 7. The boundary thicknesses of the nozzles were estimated for Reynolds numbers from 4×104 to 4×107 at Mach 6, and 4.6×104 to 4.6×106 at Mach 7 through the CFD analyses. The nozzle contours were corrected by using the boundary layer thickness defined as the 95% of the maximum speed above the wall. Viscous flow analyses for the revised configurations confirm that the exit Mach number with boundary layer correction satisfy the requirement of the design Mach number.
국내 자생식물로부터 얻어진 천연정유 추출물의 항산화 효과에 대한 연구
김소연 ( Kim,S. Y. ),김성문 ( S. M. Kim ),박세진 ( S. J. Park ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2019 강원 농업생명환경연구 Vol.31 No.1
Oxidative stress, which is induced by free radicals, causes various pathophysiological problems in the body. Natural essential oils derived from aromatic plants such as lavender and rosemary are used as additives in foods and cosmetics because of their aroma and antioxidant effects. The purpose of this study was to investigate the antioxidant activity of natural essential oils from Korean endemic plants. Natural essential oils including Mentha piperascens, Teucrium veronicoides, Citrus unshiu Peel, Angelica gigas Nakai, Zingiber officinale Roscoe, Artemisia annua L., Houttuynia cordata Thunb, Dendranthema zawadskii var. latilobum, Chrysanthemum morifolium, and Atractylodes macrocephala Koidz. were extracted by steam distillation extraction method, respectively. 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline- 6-sulphonic acid) methods were performed to measure the free radical scavenging activity of each essential oil. We found that the essential oils from the Asteraceae family including Dendranthema zawadskii var. latilobum and Chrysanthemum morifolium showed more potent antioxidant activity than those from other plants. Our findings suggest that natural essential oils derived from Asteraceae family have free radical scavenging activity, which may be explored in the prevention of health problems.