• Journal of Chest Surgery
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• v.24 no.12
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• pp.1167-1172
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• 1991

Since March 1988 we have performed 133 arteriovenous fistulae for hemodialysis in 121 patients with chronic renal failure. Of the 133 cases of arteriovenous fistulae, follow-up evaluation was possible for 80 cases which performed in 69 patients. The relation between blood flow and patency rate and duration of arteriovenous fistula was examined. The overall 6 - 12 - 18 -, and 24 - month patency rates of arteriovenous fistulae were 82%, 64%a, 62%, and 57%, respectively. The maximum blood flow was 150 ~ 350ml /min[mean 217.1$\pm$44.27]. The patency duration was evaluated in patients divided into three groups owing to maximum blood flow through the fistulae. The range of maximum blood flow was 150 ~ 200ml /min for group A, 200 ~ 250ml /min for group B, and above 250ml /min for group C. The mean duration of the patency was 10.7$\pm$7.60 months in group A, 14.9$\pm$9.82 months in group B, and 21.6$\pm$11.16 months in group C[p<0 05]. With increased maximum blood flow, the duration of the patency was longer in group A than group B and C [r=0.39, p<0. 05]. The maintenance blood flow was 100 ~ 250ml /min[mean 179.2$\pm$37.26 ml/min]. When the maintenance blood flow was above 200ml /min, long-term patency rate was higher than the group below 200ml /min[r=0.48, p<0.01]. In the same range of blood flow, patency duration of the patients with using their own blood vessels were longer than the patients with using vascular graft for A-V fistula. We concluded that the patency of the arteriovenous fistulae was closely correlated with the blood flow through the fistulae.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.23-29
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• 2005

Numerical analysis of three-dimensional viscous flow-fields in the turbine rotor passages was carried out to investigate flow physics including the interaction between secondary vortices, tip leakage vortex, and the rotor wake. The blade tip geometry was accurately modeled adopting the embedded H grid system. An explicit four-stage Runge-Kutta scheme was used for the time integration of both the mean flow and turbulence equations. The computational results for the entire turbine rotor flows, particularly the tip clearance flow and the secondary flows, were interpreted and compared with the experimental data from the Penn State turbine stage. The predictions for major features of the flow field have been found to be in good agreement with the experimental data.

• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.229-235
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• 2019

In this study, a two-dimensional oscillating foil with forward speed in a propagating wave flow field was considered. The time-mean power to maintain the heaving and pitching motions of the foil was analyzed using the perturbation theory in an ideal fluid. The power, which was a non-linear quantity of the second-order, was expressed in terms of the quadratic transfer functions related to the mutual product of the heaving and pitching motions and incoming vertical flow. The effects of the pivot point and phase difference among the disturbances were studied. The negative power, which indicates energy extraction from the fluid, is shown as an example calculation.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.6
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• pp.97-109
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• 2018

The LDC (Load Duration Curve) method can analyze river water quality changes according to flow rate and seasonal conditions. It is also possible to visually recognize whether the target water quality is exceeded or the size of the reduction load. For this reason, it is used for the optimal reduction of TPLCs and analysis of the cause of water pollution. At this time, the flow duration curve should be representative of the water body hydrologic curve, but if not, the uncertainty of the interpretation becomes big because the damaged flow condition is changed. The purpose of this study is to estimate the daily mean flow of the unit watershed using the HSPF model and to analyze the difference of the flow duration curves according to the cumulative daily mean flow rate using the NSE technique. The results show that it is desirable to construct the flow duration curve by using the daily average flow rate of at least 5 years although there is a difference by unit watershed. However, this is the result of the water bodies at the end of Han River basin watershed, so further study on various water bodies will be necessary in the future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.531-552
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• 2020

In the previous study, both the wave characteristics at the tip of composite breakwater and on caisson were investigated by applying olaFlow numerical model of three-dimensional regular waves. In this paper, the same numerical model and layout/shape of composite breakwater as applied the previous study under the action of one directional irregular waves were used to analyze two and three-dimensional spatial change of wave force including the impulsive breaking wave pressure applied to trunk of breakwater, the effect of rear region, and the occurrence of diffracted waves at the tip of caisson located on the high crested rubble mound. In addition, the frequency spectrum, mean significant wave height, mean horizontal velocity, and mean turbulent kinetic energy through the numerical analysis were studied. In conclusion, the larger wave pressure occurs at the front wall of caisson around the still water level than the original design conditions when it generates the shock-crushing wave pressure in three-dimensional analysis condition. Which was not occurred by two-dimensional analysis. Furthermore, it was confirmed that the wave pressure distribution at the caisson changes along the length of breakwater when the same significant incident wave was applied to the caisson. Although there is difference in magnitude, but its variation shows the similar tendency with the case of previous study.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.171-175
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• 2003

Numerical analysis of three-dimensional viscous flow-fields in the turbine rotor passages is carried out to investigate flow physics including the interaction between secondary vortices, tip leakage vortex, and the rotor wake. The blade tip geometry is accurately modeled adopting the embedded H grid topology. An explicit four-stage Runge-Kutta scheme is used for the time integration of both the mean flow and turbulence equations. The computational results for the entire turbine rotor flows, particularly the tip clearance flow and the secondary flows, are interpreted and compared with the experimental data from the Penn State turbine stage. Good agreement between the experimental data and the numerical prediction was achieved in the sense of the major features of the flow fields.

• Proceedings of the Korea Water Resources Association Conference
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• 1985.07a
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• pp.87-89
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• 1985

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.31-34
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• 2003

The near wake behind a sinusoidal cylinder has been investigated quantitatively using hot-wire anemometer and qualitative. The mean velocity and turbulence intensity were measured in streamwise and spanwise direction. The results show that the wake in the saddle plane has a longer vortex formation region and rapid reversed flow than that in nodal plane. The elongated vortex formation region of sinusoidal cylinder is related with drag reduction. In addition, the flow visualized with particle tracing method support the flow characteristics of sinusoidal cylinder measured by hot-wire.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.180-201
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• 2020

It has been widely known that the effect of diffracted waves at the tip of composite breakwater with finite length causes the change of standing wave height along the length of breakwater, the spatial change of wave pressure on caisson, and the occurrence of meandering damage on the different sliding distance in sequence. It is hard to deal with the spatial change of wave force on trunk of breakwater through the two-dimensional experiment and/or numerical analysis. In this study, two and three-dimensional numerical techniques with olaFlow model are used to approach the spatial change of wave force including the impulsive breaking wave pressure applied to trunk of breakwater, the effect of rear region, and the occurrence of diffracted waves at the tip of caisson located on the high crested rubble mound. In addition, it is thoroughly studied the mean wave height, mean horizontal velocity, and mean turbulent kinetic energy through the numerical analysis. In conclusion, it is confirmed that the larger wave pressure occurs at the front wall of caisson around the still water level than the original design conditions when it generates the shock-crushing wave pressure checked by not two-dimensional analysis, but three-dimensional analysis through the change of wave pressure applied to the caisson along the length of breakwater.

• Journal of Korean Clinical Health Science
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• v.6 no.1
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• pp.1048-1055
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• 2018

Purpose: The purpose of this study was to investigate the nursing students' metacognition and learning flow. Methods: The participants in this study were 272 nursing students. Between November and December 2017, data were collected through questionnaires. Data analysis was performed using PASW (SPSS) 21.0 program, and descriptive statistics, t-test, one-way ANOVA and Pearson correlation coefficients. Results: The mean metacognition of this study was 3.53/5, and mean of learning flow was 3.34/5. The significant learning flow according to metacognition level (F=46.75, p<.001). The significant correlates of metacognition were learning flow (r=.54, p<.001). Conclusions: The finding of study showed that metacognition was very important for enhancing learning flow influenced these relationship. This study suggested that it is important to develop and implement teaching and learning strategies with improved metacognition in nursing education field.