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Significance of Hemodynamic Effects on the Generation of Atherosclerosis
Sang-Ho Suh,Hyung-Woon Roh,Dong-Joo Kim,Hyuck-Moon Kwon,Byoung-Kwon Lee 대한기계학회 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.3
Atherosclerosis, which is a degenerative vascular disease, is believed to occur in the blood vessels due to deposition of cholesterol or low density lipoprotein (LDL) Atherosclerotic lumen narrowing causes reduction of blood flow due to hemodynamic features Several hypothetical theories related to the hemodynamic effects have been reported. high shear stress theory, low shear stress theory, high shear stress gradient theory, flow separation and turbulence theory, and high pressure theory However, no one theory clearly explains the causes of atherosclerosis The objective of the present study was to investigate the mechanism of the generation of atherosclerosis in the study, the database of Korean carotid and coronary arteries for geometrical and hemodynamic clinical data was established The atherosclerotic Sites were predicted by the computer simulations. The results of the computer Simulation were compared with the in vivo experimental results, and then the pathogenesis of atherosclerosis by using the clinical data and several hypothetical theories were investigated From the investigation, it was concluded carefully that the mechanism of the generation of athelosclerosls was related to the hemodynamic effects such as flow separation and oscillatory wall shear stress on the vessel walls.
( Sung Soo Kim ),( Jae Won Lee ),( Yong Joon Choi ),( Sue Young Lee ),( Sang Soo Kang ),( Nam Ho Kim ),( Yong Soo Kwon ),( Hee Jae Lee ),( Wan Joo Chun ) 한국응용약물학회 2011 Biomolecules & Therapeutics(구 응용약물학회지) Vol.19 No.4
Aberrant activation of microglia has been reported to cause neuronal damages by releasing a variety of pro-infl ammatory cytokines. Besides where microglia become active, damages have been also observed in remote places, which is considered due to the migration of activated microglia. Therefore, an agent that could suppress abnormal activation of microglia and their subsequent migration might be valuable in activated microglia-related brain pathologies. The objective of the present study was to evaluate anti-infl ammatory effects of betulinic acid on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Pretreatment of betulinic acid signifi cantly attenuated LPS-induced NO production and protein expression of iNOS. Betulinic acid also signifi cantly suppressed LPS-induced release and expression of cytokines such as TNF-α and IL-1β. Furthermore, betulinic acid signifi cantly suppressed LPS-induced MMP-9 expression, which has been suggested to play an important role in the migration of activated microglia. In order to understand the possible mechanism by which betulinic acid suppresses LPS-induced cytokine production and migration of microglia, the role of NF-kB, a major pro-infl ammatory transcription factor, was examined. Betulinic acid signifi - cantly suppressed LPS-induced degradation of IKB, which retains NF-kB in the cytoplasm. Therefore, nuclear translocation of NF-kB upon LPS stimulation was signifi cantly suppressed with betulinic acid. Taken together, the present study for the fi rst time demonstrates that betulinic acid possesses anti-infl ammatory activity through the suppression of nuclear translocation of NF-kB in BV2 microglial cells.
지능형 디지털 재설계 기법을 이용한 전력 계통의 부하 주파수 제어를 위한 강인한 퍼지 제어기 설계
Joo, Young-Hoon,Jeo, Sang-Won,Kwon, Oh-Sin 한국지능시스템학회 2000 한국지능시스템학회논문지 Vol.10 No.4
본 논문은 조속기의 밸브 위치의 제한을 고려한 불확실 비선형 전력 시스템의 부파수 제어를 위한 강인 디지털 퍼지 제어기의 설계기법을 제시한다. TSK 퍼지 모델을 이용하여 비선형 전력 시스템을 모델링한다. 리아푸노프 안정도 해석 이론에 기반하여 파라미터 불확실성을 포함한 비선형 전력 시스템의 TSK 퍼지 모델을 위한 강인 안정 조겅을 유도한다. 유도된 강인 안정 조건은 선형 행렬 부등식의 형태로 나타난다. 또한 지는형 디지털 재설계 기법을 이용하여 연속 시간상에서 운용되는 전력 시스템을 위한 디지털 제어기를 설계한다. 컴퓨터 시뮬레이션을 통하여 본 논문에서 제안된 부하 주파수 제어기 설계 기법의 효용성을 보인다. A new robust load-frequency control methodology is proposed for nonlinear power systems with valve position limits of the governor in the presence of parametric uncertaines. The TSK fuzzy model is adopted and formulated for fuzzy modeling of the nonlinear power system. A sufficient condition of the robust stabilitry is presented in the sense of lyapunov for the TSK model with parametric uncertainties. The intekkigent digital redesign technique for the uncertain power systems is also studied. The effectiveness of the robust digital fuzzy controller disign mothod is demonstrated through a numerical simulation.
( Sang Won Park ),( Jeong Yup Kim ),( Gang Ji Go ),( Eun Sil Jeon ),( Heui Jung Pyo ),( Young Joo Kwon ) 대한전해질학회 2011 Electrolytes & Blood Pressure Vol.9 No.1
30-year-old male was admitted with general weakness and drowsy mental status. He had eaten only 3-4 spoons of brown rice and fresh vegetable without salt for 3 months to treat his tic disorder, and he had been in bedridden state. He has had weight loss of 14 kg in the last 3 months. We report a patient with orthorexia nervosa who developed hyponatremia, metabolic acidosis, subcutaneous emphysema, mediastinal emphysema, pneumothorax, and pancytopenia and we will review the literature. Also, we mention to prevent refeeding syndrome, and to start and maintain feeding in malnourished patients.
Comparison of Turbulence Models in Shock-Wave/Boundary-Layer Interaction
Sang Dug Kim,Chang Oh Kwon,Dong Joo Song 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.1
This paper presents a comparative study of a fully coupled, upwind, compressible Navier-Stokes code with three two-equation models and the Baldwin-Lomax algebraic model in predicting transonic/supersonic flow. The k - ? turbulence model of Abe performed well in predicting the pressure distributions and the velocity profiles near the flow separation over the axisymmetric bump, even though there were some discrepancies with the experimental data in the shear-stress distributions. Additionally, it is noted that this model has y* in damping functions instead of y+. The turbulence model of Abe and Wilcox showed better agreements in skin friction coefficient distribution with the experimental data than the other models did for a supersonic compression ramp problem. Wilcox's model seems to be more reliable than the other models in terms of numerical stability. The two-equation models revealed that the redevelopment of the boundary layer was somewhat slow downstream of the reattachment portion.<br/>
Production of Hydantoinase from Streptomyces sp .
Kwon, Tae Jong,Lee, Joo Kyung,Lee, Sang Hoon 한국산업미생물학회 1990 한국미생물·생명공학회지 Vol.18 No.5
Hydantoinase(EC 3.5.2.2) 생산을 위해 토양에서 분리한 균주 Y-183을 배양시킨 결과 Glycerol이 탄소원으로 양호했으며, 질소원으로는 혼합된 형태의 질소원이 요구되었다. 특히 Yeast ext.와 Beef ext.가 효소생성에 크게 영향을 미쳤고, Hydantoin 유도체 및 Pyrimidine 유도체의 영향을 조사한 결과는 Uracil이 가장 양호한 결과를 나타냈다. 배양시간은 방선균의 특성상 72시간의 배양이 필요했으며 효소의 생성은 24시간 이후에 왕성하였다. 생성된 Hydantoinase는 균체내에 효소를 축적했으며 이들을 추출하여 기질로서 DL-5-Phenylhydantion 등과 반응시킨 결과 N-carbamyl-D-amino acids가 생산되는 것이 분석결과 확인되었다. In order to investigate hydantoinase-producing strain of the genus Streptomyces, 523 strains of Streptomyces sp. isolated from soils were cultivated in various media and conversion activity of the enzyme was measured to DL-5 phenylhydantoin. A number of strains producing hydantoinase were detected and among them, the strain of Streptomyces sp. Y-183 was selected as a most powerful strain to producing the enzyme. The optimal culture conditions for the production of hydantoinase of the strain were studied, and it was found that almost all hydantoinase activity was produced in the cell fraction. The maximum activity of the enzyme, 17.8 units/g of dried cells weight, was obtained when the strain was cultured at 30℃ for 72 hr in a medium containing 1.0% of glycerol, 0.5% of yeast extract, 0.5% of soytone, 0.5% of beef extract, 0.6% of KCl, 0.002% of K_2HPO_4, 0.25% of CaCO_3, 0.0002% of ZnSO_4, 0.0002% of FeSO_4, and 0.4% of uracil as an inducer, and the pH of culture broth was adjusted ranging from 7.0 to 7.5.