• Journal of Biomedical Engineering Research
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• v.13 no.4
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• pp.313-322
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• 1992

A finite analytic(FA) numerical study was performed to determin'e flow dynamics in the vicinity of an end-to-end anastomosis. Experimental data of instantaneous lumen cross-section were used to simulate steady flow through an end-to-end anastomosis In order to solve the governing axisymmetric Wavier-Stokes equations. Wall shear stresses increased proximal to the anastomosis In flow from the Penrose tubing to the PTFE graft. In flow the PTFE graft to the Penrose tubing, low wall shear stresses were observed distal to the anastomosis. The present study suggests a correlation betweerl regions of low wall shear stress and the do velopment of pnastomotic neointimal fibrous hyperplasia(ANFH ) in end-to-end anastomoses.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.1-12
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• 2016

One of the most important factors in sailing yacht design is accurate velocity prediction. Velocity prediction programs (VPP's) are widely used to predict velocity of sailing yachts. VPP's, which are primarily based on experimental data and experience of long years, however suffer limitations when applied in realistic conditions. Thus, in the present study, a high fidelity velocity prediction method using computational fluid dynamics (CFD) was proposed. Using the developed method, velocity and attitude of a 30 feet sloop yacht, which was developed by Korea Research Institute of Ship and Ocean (KRISO) and termed KORDY30, were predicted in upwind sailing condition.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3800-3804
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• 2013

In this study, molecular dynamics simulations of SPC/E (extended simple point charge) model have been carried out in the canonical NVT ensemble over the range of temperatures 300 to 550 K with and without Ewald summation. The quaternion method was used for the rotational motion of the rigid water molecule. Radial distribution functions $g_{OO}(r)$, $g_{OH}(r)$, and $g_{HH}(r)$ and self-diffusion coefficients D for SPC/E water were determined at 300-550 K and compared to experimental data. The temperature dependence on the structural and diffusion properties of SPC/E water was discussed.

• Journal of computational fluids engineering
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• v.15 no.4
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• pp.85-91
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• 2010

In this study, aerodynamic analyses based on unsteady computational fluid dynamics (CFD) have been conducted for a 2-bladed vertical-axis wind turbine (VAWT) configuration. Reynolds-averaged Navier-Stokes equations with standard $k-{\varepsilon}$ and SST $k-{\varepsilon}$ turbulence models are solved for unsteady flow problems. The experiment model of 2-bladed VAWT has been designed and tested in this study. Aerodynamic experiment of the present VAWT model are effectively conducted using the vehicle mounted testing system. The comparison result between the experiment and the computational fluid dynamics (CFD) analysis are presented in order to verify the accuracy of CFD modeling with different turbulent models.

• Wind and Structures
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• v.20 no.4
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• pp.565-578
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• 2015

A wind energy assessment is an integrated analysis of the potential of wind energy resources of a particular area. In this work, the wind energy potentials for Mauritius have been assessed using a Computational Fluid Dynamics (CFD) model. The approach employed in this work aims to enhance the assessment of wind energy potentials for the siting of large-scale wind farms in the island. Validation of the model is done by comparing simulated wind speed data to experimental ones measured at specific locations over the island. The local wind velocity resulting from the CFD simulations are used to compute the weighted-sum power density including annual directional inflow variations determined by wind roses. The model is used to generate contour maps of velocity and power, for Mauritius at a resolution of 500 m.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.93-99
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• 2009

In this paper, transient voltage response of Polmer Electrolyte Membrane Fuel Cell (PEMFC) stack is analyzed and voltage dynamic characteristic is modeled for optimal design of power conditioning system (PCS). According that the load is changed, the corresponding operating voltage of fuel cell stack is also varied with a certain deep and rising time due to the chemical and mechanical responses. This transient behavior can affect on the operation with respect of PI gain in controller, duty ratio, capacitor of capacitor and so on. So in this paper the detailed theoretical analysis of transient voltage dynamics is explained and the methodology of dynamic modeling is introduced. In addition, the validity and feasibility of the proposed dynamic model is verified by experimental results under various load conditions.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1002-1006
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• 2015

In this paper, design and analysis of permanent magnet synchronous generator for ocean thermal energy conversion (OTEC) considering magnetically coupled turbine-rotor system is discussed. In particular, the rotor dynamics considering bearing span and journal shaft diameter is highlighted. The two topologies of permanent magnet synchronous generator with magnetic coupling are employed for comparison of computed rotor dynamics and generating characteristics. The analysis results show that the critical speed of the turbine-rotor system is higher when the rotor is coupled by magnetically coupling. Finally, the experimental results confirmed the validity of the proposed design and analysis scheme and successful development.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.97-102
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• 2000

In this paper, a methodology for designing a controller based on inverse dynamics for speed control of DC motors is presented. The proposed controller consists of a prefilter, the inverse dynamic model of a system and the PI controller. The prefilter prevents high frequency effects from the inverse dynamic model. The model of the system in characterized by a nonlinear equation with coulomb friction. The PI controller regulates the error between the set-point and the system output which may be caused by modeling error, variations of parameters and disturbances. The output which may be caused by modeling error, variations of parameters and disturbances. The parameters of the model and the PI controller are adjusted offlinely by a genetic algorithm. An experimental work on a DC motor system is carried out to illustrate the performance of the proposed controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1563-1571
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• 2008

In this paper, dynamics modeling of a PEMFC is performed by electro-chemical equations. The developed PEMFC simulation model is implemented using MATLAB Simulink in order to design an optimal PCS for fuel cell systems. In addition, by use of the developed model as an input source of PCS, the validity of the proposed dynamic characteristic model of the PEMFC is verified by various simulation and experimental results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.454-459
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• 2003

We investigate the structure and properties of SiC (Silicon Carbide) nanotubes using molecular dynamics simulation based on the Tersoff bond-order potential. For small diameter tubes, the Si-C bond distance of SiC nanotubes decreases as the nanotube diameter is decreased, due to curvature of the nanotube surface. We find that Young's modulus of SiC nanotubes is somewhat smaller than that of the other nanotubes considered so far. However, Young's modulus for SiC nanotubes is larger than that of ${\beta}$-SiC and almost equal to the experimental value for SiC nanorod and SiC whisker. The strain energy of the SiC nanotubes is also lower than that of the other nanotubes. The lower strain energy of SiC nanotubes raises the possibility of synthesis of SiC nanotubes.