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손창현,서성은,한기혁 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11
외장분리해석에 적용되는 공력데이터베이스는 외장 자체의 공력 데이터베이스와 항공기 간섭에 의한 외장의 공력 데이터베이스로 구성되어 있다. 항공기 간섭에 의한 공력데이터베이스를 장착물풍동시험으로 구현하기 위해서는 시간과 비용이 필요하다. 그러므로 본 연구는 전산유체해석을 통해 항공기 주위 유동 벡터로부터 간섭 공력데이터베이스를 구성하고 유동 조건, 외장 자세에 대한 공력계수를 계산하여 항공기 간섭 유동장 내 외장의 공력계수와 비교하여 외장분리 공력데이터베이스로서의 적용 가능성을 검토하였다. The aerodynamic database for store separation analysis consists of the isolated store aerodynamic database and the interference aerodynamic database by aircraft. To make the interference database from store separation wind tunnel test needs a high cost and takes time. In this paper, the study was reviewed the feasibility of application as the interference aerodynamic database built on flow vectors that were analyzed around aircraft by computational fluid dynamics comparing with aerodynamic coefficients of the immersed store under an aircraft.
새로운 가이드 튜브를 통한 6H-SiC 단결정의 직경 확장에 관한 연구
손창현,최정우,이기섭,황현희,최종문,구갑렬,이원재,신병철,Son, Chang-Hyun,Choi, Jung-Woo,Lee, Gi-Sub,Hwang, Hyun-Hee,Choi, Jong-Mun,Ku, Kap-Ryeol,Lee, Won-Jae,Shin, Byoung-Chul 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.9
A sublimation method using the SiC seed crystal and SiC powder as the source material is commonly adopted to grow SiC bulk single crystal. However, it has proved to be difficult to achieve the high quality crystal and the process reliability because SiC single crystal should be grown at very high temperature in closed system. The present research was focused to improve SiC crystal quality grown by PVT method through using the new inner guide tube. The new inner guide tube was designed to prevent the enlargement of polycrystalline region into single crystalline region and to enlarge the diameter of SiC single crystal. The 6H-SiC crystals were grown by conventional PVT process. The seed adhered on seed holder and the high purity SiC source materials are placed on opposite side in sealed graphite crucible surrounded by graphite insulation. The SiC bulk growth was conducted around 2300 $^{\circ}C$ of growth temperature and 50 mbar in an argon atmosphere of growth pressure. The axial thermal gradient across the SiC crystal during the growth was estimated in the range of 15${\sim}$20 $^{\circ}C$/cm.
PIV study of vortexing during draining from square tanks
손창현,M. G. Ju,B. H. L. Gowda 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.4
The flow field in square tanks with various corner roundings is studied to investigate drain flow characteristics. An attempt is made to understand the mechanism of flow field responsible for vortex suppression by the different radius of rounding at the corner. For this purpose,flow visualization studies using particle image velocimetry are employed to determine the flow patterns in a square tank. Results are obtained for no draining and with draining experiments. The flow field is visualized both in horizontal and vertical planes. The results reveal that the secondary vortices formed at the corners are responsible for vortex suppression.
Reverse flow in a square duct with an obstruction at the entry
손창현,B. H. Lakshmana Gowda,Myong-Gun Ju 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.9
In this paper, the reverse flow in a square duct with an obstruction at the front (which is a square plate), is investigated using particle image velocimetry (PIV). The gap g between the obstruction and the entry to the duct was systematically varied, and it was found that maximum reverse flow occurs around a g/w value of 0.75. The velocity vectors, vorticity plots, and other details described indicate that the flow field is different compared with the two-dimensional channel case.