• Journal of computational fluids engineering
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• v.10 no.1
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• pp.45-50
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• 2005

A fundamental understanding of the flow around the wind turbine is important to investigate the performance of new type of wind turbine. This study presents the simulation of three dimensional flow fields around the Darius wind turbine as an example. Incompressible Navier-Stokes equations are used for this simulation. The rotating coordinate system that rotates in the same speed of the turbine is used in order to simplify the boundary condition on the blades. Additionally, the boundary fitted coordinate system is employed in order to express the shape of the blades precisely. Fractional step method is used to solve the basic equations. Third order upwind scheme is chosen for the approximation of the non-linear terms since it can compute the flow field stably even at high Reynolds number without any turbulence models. The flow fields obtained in this study are highly complex due to the three dimensionality and are visualized effectively by using the technique of the computer graphics.

• Journal of computational fluids engineering
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• v.10 no.1
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• pp.1-7
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• 2005

Three-dimensional numerical analysis of the flow around rectangular cylinders with various side ratios, D/H, from 0.2 to 2.0, was carried out for Reynolds number of 10³ by using a multi-directional finite difference method on a regular-arranged multi-grid. The predicted results are in good agreement with the experimental data. It is found that fluid dynamic characteristics of rectangular cylinders alternate between the high-pressure mode and the low-pressure mode of the base pressure for D/H=0.2-0.6. We show that this phenomenon is induced by the change of the flow pattern around rectangular cylinders.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.221-226
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• 2007

Viscous flow around a front end cooling fan of the car is numerically investigated. The Navier-Stokes equations and the continuity equation are solved in the flow domain. The Reynolds stresses are modelled using the $k-{\varepsilon}$ turbulence model. The governing equations are discretized with the Finite Volume Method. The pressure and the velocity are linked with the SIMPLE algorithm. Flow and pressure characteristics around the fan are investigated. The pressure sharply increases through the fan blade. Pressure variations on the pressure and suction sides of the fan are well represened in the calculations. The flow streamlines in the blade passage are nearly parallel to the blade, but the slope of streamlines increases near the tip.

• Journal of Korean Medical classics
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• v.24 no.1
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• pp.1-14
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• 2011

Background : Much Opinions of inefficiency to put the standard term of oriental medicine in and around literature into medical records. Purpose : Suggest an alternative according to analysis of differences between 'Term System' from in and around literature and term of medical records. Method : Research on the difference according to analysis of difference between producing term from in and around literature using DB Program and term from medical records. Result : The best System is that reflecting 'Korean Expression' of term of oriental medicine and part of term of western medicine and general.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.148-154
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• 2008

The Wells turbine rotor consists of several symmetric airfoil blades arranged around a central hub, and the stagger angle is 90 degrees. These characteristics simplify the total construction of OWC type wave energy converters. Although the Wells turbine is simple, the turbine produces a complicated flow field due to the peculiar arrangement of blades, which can rotate in the same direction irrespective of the oscillating airflow. In order to understand these flows, flow visualization is carried out with an oil-film method in the water tunnel. This research aims to analyze the mechanism of the 3-D flows around the turbine with the flow visualization. The flow visualization explained the influence of attack angle, the difference between fan-shaped and rectangular wings, and the sweep angle.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.530-537
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• 2013

An explicit surface potential calculation method of gate-all-around MOSFET (GAAMOSFET) devices which takes into account both interface trap charge and varying doping levels is presented. The results of the method are extensively verified by numerical simulation. Results from the model are used to find qualitative and quantitative effect of interface trap charge on subthreshold slope (SS) of GAAMOSFET devices. Further, design constraints of GAAMOSFET devices with emphasis on the effect of interface trap charge on device SS performance are investigated.

• Journal of Korean Elementary Science Education
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• v.23 no.2
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• pp.141-151
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• 2004

Pre-service teachers' understandings on magnet was investigated through the questionnaire method. The questionnaire was composed of 17 questions about the strength of magnet, the magnetized object and the direction of magnetic field around magnet. In this investigation study, 225 pre-service teachers were selected through random sampling method, who were sophomores in a National University of Education. The formation rate of the scientific conceptions on the strength of magnet was 30.3% and that on the direction of magnetic field around magnet was 53.9%. The average formation rate of scientific conception of all questions on magnet was 44.13%, which doesn't seem to be high as expected. It shows that many of subjects of the questionnaire don't understand fully the concept of moleclar magnet model and the superposition effects of magnetic field around magnet. The formation rate of the scientific conception on magnet of females who took courses in sciences in high school were higher than that of females who took courses in arts in high school, which had meaningful difference (p<.05).

• Wind and Structures
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• v.38 no.4
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• pp.295-307
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• 2024

The funnel-shaped vortex structure of tornadoes results in a spatiotemporally varying wind velocity (speed and direction) field. However, very limited full-scale tornado data along the height and radius positions are available to identify and reliably establish a description of complex vortex structure together with the resulting aerodynamic effects on the high-speed train (HST). In this study, the improved delayed detached eddy simulation (IDDES) for flow structures and aerodynamic pressures around an HST under tornado-like winds are conducted to provide high-fidelity computational fluid dynamics (CFD) results. To demonstrate the accuracy of the numerical method adopted in this study, both field observations and wind-tunnel data are utilized to respectively validate the simulated tornado flow fields and HST aerodynamics. Then, the flow structures and aerodynamic pressures (as well as aerodynamic forces and moments) around the HST at various locations within the tornado-like vortex are comprehensively compared to highlight the importance of considering the complex spatiotemporal wind features in the HST-tornado interactions.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.33-44
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• 2015

Purpose: This study is to evaluate the clinical significance of the platform switching concept by comparing the marginal bone loss around platform-matched and platform-switched implants. Materials and Methods: Date of implant placement, diameter, length, implant-abutment connection type and absence of splinting prosthesis were investigated on patients who performed treatment with implant placement at Wonkwang University Dental Hospital Implant Center. To measure the marginal bone loss around implants, periapical radiographs of patient were used when implant was placed and when visited the center most recently by using the program, Emago advanced v5.6. Results: As a result of observing on 150 implants of 82 patients for 6 - 63 months, platform-matched implants showed $1.16{\pm}0.54mm$, platform-switched implants showed $0.68{\pm}0.27mm$ of marginal bone loss. Conclusion: It was considered that there is the positive effect to reduce marginal bone loss around platform-switched implants.

• Journal of Periodontal and Implant Science
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• v.38 no.3
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• pp.493-502
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• 2008

Purpose: The purpose of this study is to investigate on the regenerative capacity by using different size of graft materials around bony defect around implant. Material and Methods: Dental implant fixtures(Bio-TIS, Korea) were placed into the tibia of 8 rabbits. After placement of implant, artificial defects were created for each group, and the size of bone graft materials were used according to each designated group. 4 weeks after surgery, 8 rabbits were sacrificed. The histologic and histomorphometrical study were done for comparison of the regenerative capacity using $80-90{\mu}m$ and $200{\sim}1000{\mu}m$ size of grafting materials of OCS-$B^{(R)}$. Result: Matured bone formation was significantly increased more in Group E1($80-90{\mu}m$) than in Group E2($200{\sim}1000{\mu}m$). Group E1($80-90{\mu}m$) showed more significant augmentation in marginal length of graft material per unit area than Group E2($200{\sim}1000{\mu}m$). Group E1($80-90{\mu}m$) showed more interspace in graft material than Group E2($200{\sim}1000{\mu}m$). Control group showed no new bone formation around and inside of implanted fixture. Conclusion: Small grafting material size has great influence on bone regeneration.