• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1404-1406
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• 1995

In this paper, argon gas was used for numerical analysis of an arc in a cutting plasma torch driven by constant current. We established nozzle-constricting type torch domain and calculated steady state characteristics of argon arc plasma using the control volume method(CVM). For simplicity, we assumed that the flow field is laminar and the local thermodynamic equilibrium(LTE) prevails in all domain regions. We also neglected cathode-fall and anode-fall effects. Considering magnetic pinch effect and viscosity effect, we solved the momentum equation. Voltage drop in the arc column due to input current was calculated from the temperature field obtained by the energy balance equation.

• Nuclear Engineering and Technology
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• v.31 no.4
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• pp.432-443
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• 1999

Using a two-dimensional numerical model, nuclide transport in the buffer between the canister and adjacent rock in a high-level radioactive waste repository is dealt with. Calculations are made for a typical case with a three-member decay chain, $^{234}$ U longrightarrow $^{230}$ Th longrightarrow $^{226}$ Ra. The solution method used here is based on a physically exact formulation by a control volume method directly integrating the governing equation over each control volume.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.337-342
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• 2007

This paper proposes a helmet-type whole-head brain stimulator system considering a realistic head geometry. For more accurate design and computer simulations, a realistic volume conductor model was adopted and the current evoked on human cerebral cortex was analyzed using the boundary element method (BEM). To obtain a more focalized evoked current around the target points, various coil configurations were tested and an average targeting error of about 10 mm was obtained.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.138-147
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• 2011

Modeling fishing-gear systems is essential to better understand the factors affecting their movement and for devising strategies to control movement. In this study, we present a generalized mathematical modeling methodology to analyze fishing gear and its various components. Fishing gear can be divided into a finite number of elements that are connected with flexible lines. We use an algorithm to develop a numerical method that calculates precisely the shape and movement of the gear. Fishinggear mathematical models have been used to develop software tools that can design and simulate dynamic movement of novel fishing-gear systems. The tool allowed us to predict the shape and motion of the gear based on changes in operation and gear design parameters. Furthermore, the tool accurately calculated the swept volume of towed gear and the surrounding volume of purse-seine gear. We analyzed the fished volume for trawl and purse-seine gear and proposed a new definition of fishing effort, incorporating the concept of fished space. This method may be useful for quantitative fishery research, which requires a good understanding of the selectivity and efficiency of fishing gear used in surveys.

• Journal of the Korea Computer Graphics Society
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• v.8 no.1
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• pp.1-11
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• 2002

In order to widely use volume rendering technology in practical fields, a user should be able to control the classification parameter interactively and extract a meaningful information easily from the 3D data as fast as it can be. Previous work on an accelerating volume rendering reconstructs an isotropic volume from an anisotropic one and classifies in pre-processing time and then renders the classified volume rapidly in run time. But, this traditional step may result in long pre-processing time and no real-time feedback. In this paper, we present an efficient classification and rendering method that allows a user to set the opacity transfer function interactively at rendering time on a personal computer without special-purpose hardware.

• Journal of Korean Port Research
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• v.13 no.1
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• pp.167-174
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• 1999

Numerical analysis of two-fluid flows for both water and air is carried out. Free-Surface flows with an arbitrary deformation have been simulated around two dimensional submerged hydrofoil. The computation is performed using a finite volume method with unstructured meshes and an interface capturing scheme to determine the shape of the free surface. The method uses control volumes with an arbitrary number of faces and allows cell-wise local mesh refinement. the integration in space is of second order based on midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation in time through three time levels The linear equation systems are solved by conjugate gradient type solvers and the non-linearity of equations is accounted for through picard iterations. The solution method is of pressure-correction type and solves sequentially the linearized momentum equations the continuity equation the conservation equation of one species and the equations or two turbulence quantities.

• Journal of Mechanical Science and Technology
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• v.14 no.7
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• pp.789-795
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• 2000

Free-surface flows with an arbitrary deformation, induced by a submerged hydrofoil, are simulated numerically, considering two-fluid flows of both water and air. The computation is performed by a finite volume method using unstructured meshes and an interface capturing scheme to determine the shape of the free surface. The method uses control volumes with an arbitrary number of faces and allows cell wise local mesh refinement. The integration in space is of second order, based on midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation in time through three time levels. The linear equations are solved by conjugate gradient type solvers, and the non-linearity of equations is accounted for through Picard iterations. The solution method is of pressure-correction type and solves sequentially the linearized momentum equations, the continuity equation, the conservation equation of one species, and the equations for two turbulence quantities. Finally, a comparison is quantitatively made at the same speed between the computation and experiment in which the grid sensitivity is numerically checked.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.213-220
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• 1998

The conventional discrete-ordinates method (DOM) is modified and developed for the analysis of two-dimensional axisymmetric cylindrical enclosure with curved wall. The objective of the present work is to extend the capability of the conventional DOM into a general axisymmetric geometry like nozzle-shaped enclosure, by adopting the arbitrary control angle as was done in the finite-volume method (FVM), while keeping the same two-dimensional solution procedure as in the conventional DOM. The present method is validated by applying it to three different benchmark problems of axisymmetric enclosure containing absorbing, emitting and scattering medium. Results presented in this work not only support the solution accuracy, but also moderate efficiency in the numerical calculation of axisymmetric radiation problem.

• Proceedings of the Korean Society of Rheology Conference
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• 2002.11a
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• pp.63-66
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• 2002

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.1-13
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• 1993

The three-dimensional numerical analysis for in-cylinder flow of four-valve engine without intake port has been successfully computed. These computations have been performed using technique of the general coordinate transformation based on the finite-volume method and body-fitted non-orthogenal grids using staggered control volume and covariant variable as dependent one. Computations are started at intake valve opening and are carried through top-dead-center of compression. A k-$\varepsilon$model is used to represent turbulent transport of momentum. The principal study is the evolution of interaction between mean flow and turbulence and of the role of swirl and tumble in generating near TDC turbulence. Results for three different inlet flow configuration are presented. From these results, complex flow pattern may be effective for promoting combustion in spark-ignition engines and kinetic energy of mean flow near TDC is well converted into turbulent kinetic energy.