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( Do Kang ),( Hs Seo ),( Bg Choi ),( Cw Choi ),( Eunmi Lee ),( Jp Kim ),( Sk Lee ),( Si Lim ),( Sw Kim ),( Jo Na ),( Cu Choi ),( He Lim ),( Jw Kim ),( Ej Kim ),( S-w Rha ),( Cg Park ),( Dj Oh ) 대한내과학회 2013 대한내과학회 추계학술대회 Vol.2013 No.1
Objectives: Statins for the prevention of CVD are known to be as diabetogenic. However most clinical trials suggested that current statin therapy in moderate to high cardiovascular risk should not be changed, due to the outwheighing benefits of statins on CVD prevention. We investigated which clinical variables on treatment are most closely associated with the development of 24 month MACE (all death, any myocardial infarction and target vessel revascularization) in DES implanted patients on statin therapy. Methods: Total 299 patients undergone DES implantation with taking statins for secondary prevention were involved. Tracking the development of MACE within 24 month post-PCI, 12 month follow up clinical variables showing significant correlation to the event were evaluated. To discover whether the changes in clinical parameters over the 12 month follow up are associated with the event development, subtractions from baseline to follow up lab results and absolute value conversion of the subtractions are obtained. Variables showing significant difference between the groups were put into the multivariate analysis and into the survival curve model. Results: Fasting glucose at 12 month were significantly higher in the event group. Subtractions from baseline to 12 month follow up showed no significant differences between the groups, however, absolute change in fasting glucose revealed a significant difference. In multivariate analysis, absolute change in fasting glucose greater than 17 mg/dL/year was strongly associated with the event development. When study population was further divided into four groups by using IQR of absolute change in fasting glucose, greater absolute change during 12 month post-PCI showed a higher risk of 24 month MACE development in both multivariate analysis and survival curve models. Conclusion: The findings suggest that greater absolute change in fasting glucose during 12 month post-PCI is an independent risk factor for 24 month MACE development in DES implanted patients on statin therapy. Relative glucose control impairment described as absolute change in fasting glucose in the current study might be responsible for the development of 24 month MACE.
Evaluation of pressure and viscous drags of a rising bubble at small Reynolds numbers
Long Cu Ngo,Hyoung Gwon Choi 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3
Pressure and viscous drags acting on a bubble rising in a viscous fluid are numerically estimated to obtain the corresponding drag coefficients that are rarely reported in the existing papers. The numerical method has been successfully validated by solving the existing benchmark problems of a bubble rising in a quiescent liquid at various flow regimes. For spherical cap bubbles, the formula of total drag coefficient is proposed in a similar form to that by viscous potential flow theory expressed by the Reynolds number, and the corresponding formulas for pressure and viscous drag coefficients are derived. Furthermore, the effect of the density ratio of a bubble and the surrounding liquid on terminal velocity is also investigated for fixed Morton and Eotvos numbers: the lighter bubble has a higher terminal velocity having an asymptotic value as the density ratio increases although the Reynolds numbers based on the terminal velocity are nearly constant.
A coupled level set/volume of fluid method for simulation of two-phase flow on unstructured grids
Long Cu Ngo,Hyoung Gwon Choi,장경식 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
We present a fully coupled level set and volume of fluid method for free surface flow simulations on unstructured grids in two- and three-dimensions. The evolution of the level set function and the volume fraction are updated at each time step. The level set advection equation is solved by a least squares weighted residual method while the volume fraction advection is solved using an unsplit Eulerian-Lagrangian scheme. The reconstruction of the interface in the volume of fluid method is performed using the volume fraction information together with the normal vector obtained from the level set function. The reconstructed interface is then used to reinitialize the level set function. Thanks to the fully coupling of the two methods, the interface reconstruction is carried out efficiently and the mass conservation is preserved exactly. The proposed method is validated against several benchmarks and is coupled with the incompressible Navier-Stokes solver to solve two-phase flow problems. Numerical results show that the method is capable of resolving complex interface changes efficiently and accurately.