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다공 표면 효과를 반영한 극초음속 경계층 선형 안정성 해석기법 구축
박종형,박동훈 한국항공우주학회 2024 韓國航空宇宙學會誌 Vol.52 No.5
비행체 표면에서의 마찰항력과 열전달은 경계층의 상태와 매우 밀접하게 연관되기 때문에 극초음속 비행체의 열공력성능, 임무성능을 향상시키기 위한 경계층 천이 제어 연구가 큰 관심을 받고 있다. 본 연구에서는 다공 표면이 극초음속 경계층 안정화와 천이에 미치는 영향을 분석하기 위해 선형 안정성 이론 기반의 안정성 해석기법을 구축하였다. 구축한 해석기법으로 날카로운 원뿔 위 극초음속 경계층에 대한 Mack 2차 모드의 증폭률을 계산하고 선행연구 결과와의 비교를 통해 검증을 수행하였다. 검증해석 결과 다공 표면 적용에 따라 최대 증폭률이 감소하였으며, 불안정한 영역이 상류로 이동함을 확인하였다. 기공 반경, 간격, 깊이, 단면 형상과 같이 다공 형상 파라미터에 따른 효과를 분석하였으며, 기공 내의 희박효과와 표면에서의 열적 어드미턴스가 해석 결과에 미치는 영향을 평가하였다. 또한, 반경험적 천이 예측 기법을 기반으로 다공 표면의 천이 지연 효과를 분석하였다. The control of the boundary layer transition has been of great research interest to improve the aerothermodynamic performance and mission performance of hypersonic flight vehicles, since the skin friction drag and surface heat transfer depend significantly on the state of boundary layer. A stability analysis method based on the linear stability theory is established to investigate the effects of porous surface on the stability and transition of the hypersonic boundary layer. The method is validated by calculating growth rates of the Mack second mode for the hypersonic boundary layer over a sharp cone and comparing the results with previous study. The analysis results show that the application of the porous surface attenuates the maximum growth rate and shifts the unstable region upstream. The effects of the geometric parameters such as pore radius, spacing, depth, and cross-sectional shape are investigated. The influences of taking into account the rarefaction effect inside the pore and the thermal admittance at the surface on the analysis results are also evaluated. In addition, the potential capability of the porous surface to delay the transition is also investigated based on the semi-empirical transition prediction method.
Power Conditioning System for a Grid Connected PV Power Generation Using a Quasi-Z-Source Inverter
박종형,노의철,전태원,김흥근 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.1
This paper presents a grid connected photo-voltaic system using a quasi-Z-source inverter (QZSI) for power stage reduction. The power stage can be reduced because of an additional shoot-through stage which is a characteristic of QZSI. Therefore, by utilizing a QZSI the system’s efficiency can be increased. In this paper, for applying a QZSI to a PV system, control methods such as maximum power point tracking (MPPT), point of common coupling (PCC) current control and PWM are studied and verified through simulation and experiment. In order to explain the above controllers, the characteristics of a QZSI are first analyzed. Then the MPPT control technique with a modified P&O method, the PCC current control for the regulation of the dc-link capacitor voltage and the PWM methods for the proposed system are explained. The feasibility of the proposed algorithm is verified through simulation and experiment with a 3kW system.
단치소요산가미방이 Dexamethasone 처리한 랫드의 두개골 세포에 미치는 영향
박종형,황귀서,Park, Jong-Hyeong,Hwang, Gwi-Seo 대한예방한의학회 2006 대한예방한의학회지 Vol.10 No.2
It is well known that glucocorticoid may induce osteoporosis as its side effect in long-term therapy. The inhibition of osteoblast by glucocorticoid is also recognized as its action mechanism of decreased bone formation. In this study, the effect of DSG, Danchisoyosangamibang, on the differentiation and function of osteoblastic cells was investigated. The osteoblastic cells were isolated from rat calvariae using collagenase treatment. The cell counting, enzyme activity assay, MTT assay, collagen content assay were done to determine the cell proliferation, intracellular alkaline phosphatase (ALP) activity, bone martrix production, and cell apoptosis. DSG enhanced the cell proliferation after the culture for 10 days. ALP activity and total protein synthesis, and intracelluar collagen synthesis were increased time dependently when the cells were treated with DSG in the presence of dexamethasone. And, DSG restored calvarial cell function decreased by dexamethasone.
혈부축어탕(血府逐瘀湯)이 혈전생성관여인자(血栓生成關與因子)에 미치는 영향(影響)
박종형,한양희,전찬용,김동우,박세기,이청정혜,고승희,고재철,최유경,김영선,Park, Jong-Hyung,Han, Yang-Hi,Jun, Chan-Yong,Kim, Dong-U,Park, Se-Gi,Lee, Chung-Jung-Hye,Go, Seung-Hi,Go, Jae-Chul,Choi, You-Kyung,Kim, Young-Sun 대한한방내과학회 2000 大韓韓方內科學會誌 Vol.21 No.5
Purpose : To investigate the inhibitory effect of HCE on platelet aggragation and erythrocyte deformiability, we performed following experiments. Methods : Concentrated Hyulbuchukotang (HCE) was fed to rats for 10days. We compare normal group with $500{\beta}{\Sigma}/{\beta}{\Sigma}$-high dose group and $100{\beta}{\Sigma}/{\beta}{\Pi}$-low dose group. Results : HCE enhanced the blood filtration rate, erythrocyte deformiability, reduced the platelet aggreablilty and inhibited granule release from collagen stimulated platelet, the prostaglandin synthesis in platelat. Conclusion : HCE should inhibit thrombos formation due to platelet hyperaggraeability and reduction of erythrocyte defonmiability.
보양환오탕(補陽還五湯)이 혈전생성관여인자(血栓生成關與因子)에 미치는 영향(影響)
박종형,한양희,전찬용,김동우,박세기,이청정혜,고승희,고재철,최유경,박선영,Park, Jong-Hyung,Han, Yang-Hi,Jun, Chan-Yong,Kim, Dong-U,Park, Se-Gi,Lee, Chung-Jung-Hye,Go, Seung-Hi,Go, Jae-Chul,Choi, You-Kyung,Park, Sun-Young 대한한방내과학회 2000 大韓韓方內科學會誌 Vol.21 No.5
Purpose : To investigate the inhibitory effect of BHE on platelet aggregation and erythrocyte deformability, we performed following experiments. Methods : Concentrated Boyanghwanotang (BHE) was fed to rats for 10days. High dose group was treated with $500{\beta}{\partial}/kg$ and low dose group with $500{\beta}{\partial}/kg$. Results : BHE enhanced the blood filtration rate, reduced the platelet aggregability, inhibited granule release from collagen-stimulated platelet, the prostaglandin syn-thesis in platelet and enhanced erythrocyte deformability. Conclusion : BHE should inhibit thrombos formation due to platlete hyperaggregabili-ty and reduction of erythrocyte deformabi-lity.