http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
원심압축기용 베인 디퓨저 내부유동의 수치해석 및 성능평가
최윤호,강신형,이장춘,Choi, Yun-Ho,Kang, Shin-Hyoung,Lee, Jang-Chun 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.10
A three dimensional compressible Navier-Stokes code is developed to analyze flowfields and performance of a vaned diffuser in a centrifugal compressor. It employs scalar implicit approximate factorization, finite volume formulation, second order upwind differencing and a two-equation $q-{\omega}$ turbulence model based on the integration to the wall. Pressure recovery and loss coefficients of a vaned diffuser are evaluated using a developed computer code. The simulated three dimensional flows show how through flow structure affects pressure recovery performance and loss coefficients of a vane for design and off-design inlet flow angles. Development of complex three dimensional flow over the inlet region and leading edge are very influential to the overall flow and performance.
최윤호,최용준,김주철,정관수,Choi. Yun-Ho,Choi. Yong-Joon,Kim. Joo-Cheol,Jung. Kwan-Sue 한국방재학회 2011 한국방재학회논문집 Vol.11 No.3
본 연구에서는 대상유역을 지표면과 하천 격자로 분할한 후, Manning 식을 기반으로 각 격자 중심에서 유역 출구점까지의 유하시간을 계산하여 등시간별 체적유량을 산정하였으며, 이로부터 유역의 동수역학적 특성인 특성유속을 고려한 직접유출수문 곡선을 도출하였다. 대상유역은 보청천유역의 산성유역을 선정하였다. 대상유역에 대한 매개변수 산정 결과 흐름누적값은 3800, K는 3.3으로 결정되었다. 보정된 매개변수를 실제사상에 대해 적용하여 검증한 결과 첨두유량과 첨두시간의 평균 절대오차는 각각 3.41%, 0.67 hr로 비교적 양호한 모의결과를 나타냈다. 또한 유효우량에 따른 유하시간별 기여면적 주상도를 분석한 결과 본 연구에서 적용된 모형은 강우강도에 따른 유역의 수리학적 특성을 잘 표현하고 있음을 알 수 있었다. In this study, after the target basin was divided into both overland and channel grids, the travel time from center of each grid cell to watershed`s outlet was calculated based on the manning equation. Through this process, volumetric discharge was calculated according to the isochrones and finally, the direct runoff hydrograph was estimated considering watershed`s hydrodynamic characteristics. Sanseong subwatershed located in main stream of Bocheong basin was selected as a target basin. The model parameters are only two: area threshold and channel velocity correction factor; the optimized values were estimated at 3,800 and 3.3, respectively. The developed model based on the tuned parameters led to well-matching results between observed and calculated hydrographs (mean of absolute error of peak discharge: 3.41%, mean of absolute error of peak time: 0.67 hr). Moreover, the analysis results regarding histogram of travel time-contribution area demonstrates that the proposed model characterizes relatively well hydrodynamic characteristics of the catchment due to effective rainfall.
IT 거버넌스를 위한 Val IT 기반의 IT 서비스 관리 성과지표 모델
최윤호 ( Yun-ho Choi ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.2
기업들은 ITIL 기반의 IT 서비스 관리체계 도입으로 IT 서비스에 대한 객관적인 가치 평가를 기대하고 도입한다. 하지만 기업들의 IT 서비스 관리체계의 성과지표들은 관리 중심적인 성과모델로써 가치 평가보다는 IT 운영 관리 중심으로 활용되고 있으며, IT 거버넌스의 전략적 의사결정을 위한 가치 연계와 책임 추적성, 성과 측정 및 위험 관리를 지원하지 못하고 있다. 가치 중심의 성과지표 모델을 통해 IT 거버넌스를 지원하고, 기업의 지속적이고 체계적인 투자관리를 통해 기업 가치향상과 투명한 IT 투자에 기여하길 기대한다.
비만세포 매개 아나필락시스에 대한 fraxin의 억제 효과
최윤호(Yun Ho Choi) 한국생약학회 2023 생약학회지 Vol.54 No.4
Mast cells plays a key role in the immediate-type hypersensitivity. Fraxin, the active constituent isolated from Cortex Fraxini, has been known to have anti-inflammatory capacity. However, the effects of fraxin in mast cell-mediated anaphylactic reaction have not been fully shown. Therefore, the in vivo anti-anaphylactic activity of fraxin was evaluated using rodent models of anaphylaxis. Additionally, we assessed the mechanism underlying the mast cell stabilizing effect of fraxin, with a specific focus on histamine release from rat peritoneal mast cells (RPMC). Systemic anaphylaxis-like reaction, plasma histamine levels, and ear swelling response were attenuated in mice treated with fraxin. Fraxin also suppressed passive systemic and cutaneous anaphylaxis. Furthermore, fraxin dose-dependently blocked histamine release from RPMC evoked by histamine liberators or the antigen-antibody reaction, which is in agreement with in vivo findings. To elucidate the mechanism of action of fraxin, both calcium influx and intracellular cAMP content in RPMC were assessed. In RPMC stimulated by compound 48/80 or ionophore A23187, fraxin decreased calcium uptake into the cells. Moreover, fraxin increased the intracellular cAMP level and significantly prevented compound 48/80-induced cAMP reduction in RPMC. Taken together, the inhibition of histamine release by fraxin appears to be mediated partly through the suppression of calcium uptake as well as the augmentation of cAMP levels. In conclusions, the clinical application of fraxin in the immediate-type hypersensitivity may be feasible.