• 한국수자원학회논문집
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• 제45권5호
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• pp.473-480
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• 2012

고정확도를 보장할 수 있는 Compact Finite Volume Method를 이용하여 수심적분형 흐름 모형과 수심평균된 이송확산 방정식을 해석하는 수치모형 개발과정을 기술하였다. 이차원의 흐름과 파랑의 상호작용에 대한 실험결과와 제시된 수치모형을 이용한 계산결과는 양호하게 일치하였다. 일차원과 이차원공간에서의 흐름에 의한 스칼라의 이송에 관한 수치모의에서도 수차확산이 거의 발견되지 않았고, 매우 정확히 일치하였다. 개수로에서의 난류혼합에 관한 수치모의 결과에서도 합리적인 스칼라의 혼합양상이 관찰되었다.

• 연구논문집
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• 통권33호
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• pp.17-25
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• 2003

In this work, thermal design of a PCR chip for LOC is systematically conducted. From the numerical simulation of a PCR chip based on the finite volume method, how to control the average temperature of a PCR chip and the temperature difference between the denaturation zone and the annealing zone is presented. The average temperature is shown to be controlled by adjusting heat input and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. To reduce the time required, a heat sink for the cooler is not included in the calculation domain for the PCR chip and heat sink design is conducted separately by using a compact modeling method, the porous medium approach.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.115-120
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• 2003

In this work, a continuous-flow micro-PCR system is systematically designed. From the numerical simulation based on the finite volume method, adapting oneself to a new environmental temperature without an external temperature controller is shown to be possible and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. In addition, appropriate geometry of a heat sink for the cooler is determined by using a compact modeling method, the porous medium approach.

• 전기학회논문지P
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• 제64권3호
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• pp.121-124
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• 2015

In this paper, we developed the compact Doppler radar using the compact dual-circularly polarized antenna for medical application. The operating frequency is 2.47 GHz for considering ISM band. In order to decrease the size of the entire system, we designed the compact antenna and located the circuit board at the back of the antenna. The simulation of the proposed antenna was performed by the finite difference time domain (FDTD) method. The total volume of the proposed system is $65{\times}45{\times}6mm^3$ including the antenna. From the experiment, the developed bio-radar could be used to support the device for medical applications.

• Advances in Energy Research
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• 제1권1호
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• pp.53-78
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• 2013

Methane carbon dioxide reforming (MCDR) is a promising way of utilizing greenhouse gas for hydrogen-rich fuel production. Compared with other types of reactors, Compact Reformers (CRs) are efficient for fuel processing. In a CR, a thin solid plate is placed between two porous catalyst layers to enable efficient heat transfer between the two catalyst layers. In this study, the physical and chemical processes of MCDR in a CR are studied numerically with a 2D numerical model. The model considers the multi-component gas transport and heat transfer in the fuel channel and the porous catalyst layer, and the MCDR reaction kinetics in the catalyst layer. The finite volume method (FVM) is used for discretizing the governing equations. The SIMPLEC algorithm is used to couple the pressure and the velocity. Parametrical simulations are conducted to analyze in detail the effects of various operating/structural parameters on the fuel processing behavior.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1869-1874
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• 2004

Acoustic pressure field around the cross-flow fan is predicted by a hydrodynamic-acoustic splitting method. Unsteady flow field is obtained by solving the incompressible Navier-Stokes equations using an unstructured finite-volume method on the triangular meshes, while the acoustic waves generated inside the cross-flow fan are predicted by solving the perturbed compressible equations(PCE) with a 6th-order compact finite difference method. Computational results show that the acoustic waves of BPF tone are generated by interactions of the blades wakes with the stabilizer, which then are reflected from the rear-guider and mainly propagate towards the fan inlet. Also, a directivity of BPF noise predicted by the PCE is noticeably different from that of the FW-H equations, in which a fan casing effect cannot be included.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2271-2276
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• 2015

A superconducting synchronous generator (SCSG) can be expected to decrease the size and weight compared to conventional tidal current generators. This paper proposes an optimal design of a 2 MW class SCSG for a tidal current power generation system. The proposed optimal design of the SCSG will reduce the length of the high-temperature superconducting wire as well as the weight and volume of the SCSG. The 3D finite element method is used to analyze the magnetic field distribution. The optimized 2 MW SCSG is compared with a 2 MW conventional generator. As the optimized SCSG is more compact and lighter than a conventional generator, it will be efficiently applied to practical tidal power systems.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.392-394
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• 2011

This paper is concerned about the hydrodynamic coefficients of hydrofoil. We discretized the incompressible Navier-Stokes equation with second order Runge-kutta for the time in the second order compact scheme for the spatial. The three-dimensional CFD code based on hybrid mesh on the finite volume method is used to simulate flow around NACA series foils. Lift and drag coefficient is calculated for several NACA series foils using different mesh types. Our aim is to obtain the lift and drag coefficient to evaluate the robustness of the solver and to shaw the advantage of using trim tab at the trailing edge. It concludes with a discussion of results and recommendations for future work.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.193-197
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• 2002

In this study, the casting/forging process was applied to the Shift-Fork, a manual transmission part of automobiles. In the casting experiments, the effects of additives, Sr, Ti＋B and Mg, on the mechanical properties and the microstructure of a cast preform were investigated. When 0.03% Sr were added into the molten aluminum alloy, the finest silicon-structure was observed in the cast preform and the highest tensile strength and elongation accomplished. And when 0.2% Ti＋B were added into the molten Al-Si alloy, the highest values of tensile strength were obtained. The maximum hardness was in case of 0.2% Mg. In the forging experiment, it was confirmed that the optimal configuration of the cast preform could be predicted by FE analysis. To minimize the cost as the press size, the compact shape of preform was proposed to reduce the volume of flash. The modification of shape in designing preform was performed to attain a satisfactory performance in the areas where the mechanical strength were more required. By using FVM(Finite Volume Method) software, it was verified that a proposed casting design was available. To identify the relationship between effective strain and mechanical properties of the final forged product, the compression test was performed. As the result, the tensile strength and elongation of a cast preform were much higher than before forging. The minimum forging temperature was found 40$0^{\circ}C$ to save heating time.

• 한국전산유체공학회지
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• 제19권3호
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• pp.52-61
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• 2014

The present paper deals with the efficient computation of higher-order CFD methods for compressible flow using graphics processing units (GPU). The higher-order CFD methods, such as discontinuous Galerkin (DG) methods and correction procedure via reconstruction (CPR) methods, can realize arbitrary higher-order accuracy with compact stencil on unstructured mesh. However, they require much more computational costs compared to the widely used finite volume methods (FVM). Graphics processing unit, consisting of hundreds or thousands small cores, is apt to massive parallel computations of compressible flow based on the higher-order CFD methods and can reduce computational time greatly. Higher-order multi-dimensional limiting process (MLP) is applied for the robust control of numerical oscillations around shock discontinuity and implemented efficiently on GPU. The program is written and optimized in CUDA library offered from NVIDIA. The whole algorithms are implemented to guarantee accurate and efficient computations for parallel programming on shared-memory model of GPU. The extensive numerical experiments validates that the GPU successfully accelerates computing compressible flow using higher-order method.