• Journal of Korea Water Resources Association
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• v.38 no.3 s.152
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• pp.179-188
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• 2005

This study on the HwaBuk Multipurpose Dam showed that two- and three- dimensional numerical model experiments, as well as hydraulic model experiments, can be useful analysis tools for engineers. A commercially available RMA2, which solves the shallow water equations, and FLOW-3D, which solves the Reynolds averaged Navier-Stokes equations, were used to simulate the hydraulic model setup. Numerical simulation results on the following were compared with the hydraulic model results: the flow in the reservoir basin and the approaching channel; the discharge in the overflow weir; the water surface profiles in the rollway, chute, and stilling basin; and the pressure distributions in the rollway. It was shown that there is a reasonably good agreement between the numerical model and the hydraulic model for the most of computations. There were, however, some differences between the numerical simulation results and hydraulic model results for the hydraulic jump in the stilling basin because of air entrainment effect.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.509-512
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• 2008

본 논문에서는 원전 증기발생기세관 진단을 위한 와전류탐상의 전자기 수치해석을 수행하였다. 전자기적 특성을 해석하기 위하여 맥스웰 방정식을 이용하여 지배방정식을 유도하였고, 3차원 전자기 유한요소 프로그램인 OPERA 3D를 이용하여 전자기 수치 해석을 수행하였다. 신호해석을 위해 사용된 프로브의 종류는 배열와전류프로브이며, FBH 결함의 신호를 해석하였다. 결함의 깊이는 세관 두께의 40[%], 60[%] 및 100[%]로 하였다. 시험주파수는 100[kHz], 300[kHz], 400[kHz]를 사용하였고, 각각의 결함 및 시험주파수에 대한 결과를 비교 분석하였다. 본 논문의 결과는 앞으로 배열와전류프로브를 이용하여 원전 증기발생기세관 진단을 할 경우 신호 해석에 도움이 될 것으로 사료된다.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.487-494
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• 2008

The numerical simulation of point-to-plane discharge of nitrogen at medium pressure has been achieved by a quasi-2d numerical model. In the model, we calculate the distributions of electric charges which are varying as temporal and space and determine the electric field depending on space charge distribution by solving Poisson's equation. The continuity equations are treated numerically by using FCT (Flux-Corrected Transport) Algorithm and FEM (Finite Element Method). The numerical simulation results make us to understand the physical characteristics of nitrogen discharge at 50 torr. The comparison with experimental results[1] shows a good qualitative agreement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.363-366
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• 2005

A micro flow sensor on silicon substrate allows the fabrication of small components where many different functions can be integrated so that the functionality of the sensors can be increased. Further more, due to the small size of the elements the sensors can be quite fast. A thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. In normal, a mass flow sensor is composed of a central heater and a pair of temperature sensing elements around the heater. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensors and a central heater was proposed and numerically simulated by the Finite difference formulation to confirm the feasibility of the flow sensor structure.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.61-68
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• 1999

We have measured pressure distributions within the diffuser and pressures at the inlet and outlet of the compressor in orde to match impeller and low-solidity diffuser of 500RT centrifugal refrigerant-compressor which has been developed in LG Cable Ltd. Modified Stanitz equation is used to predict the measured data by tuning several parameters and then is validated. Using the validated parameters and modified Stanitz equation, we have obtained data necessary to design the diffuser.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1230-1231
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• 2011

이 논문은 전차원 상태 관측기 기반의 EEMF(Extended Electro-Motive Force) 모델을 이용한 IPMSM(Interior Permanent Magnet Synchronous Motor:매입형 영구 자석 동기 전동기)센서리스 제어 기술을 제안한다. 임의의 ${\gamma}-{\delta}$축 상에서 IPMSM 상태 방정식을 전개하고 이를 전차원 상태 관측기로 구현해 Extended EMF(역기전력)성분을 추정한다. 추정 성분을 이용해 제어각의 오차를 구하고 PI제어기를 사용해 제어각의 오차를 0으로 수렴시켜 전동기 회전 속도를 추정한다. 추정 속도를 적분해 제어각을 얻고, IPMSM 센서리스 제어를 수행한다. 제안한 알고리즘은 실험을 통해 그 타당성을 검증한다.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.22-24
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• 2003

유도성 기동 영구자석 전동기의 경우 고효율성 및 자기동성으로 인해 현재 산업계에서 많이 사용되고 있는 유도기를 대체할 가능성이 크다. 정상 상태에서는 영구자석 동기 전동기로 작동하며 기동시에는 유도바의 역할로 유도기로서 동기화에 이르게 된다. 이때, 적절한 설계가 이루어지지 않으면 기동 또는 동기화에 실패할 수 있으므로 기동시의 과도특성 해석은 매우 중요하다. 본 논문에서는 기계 방정식과 결합된 유한요소해석 프로그램을 이용하여 전동기의 기동 및 동기화 특성을 해석하고자 한다. 해석의 타당성을 검증하기 위하여 시험용 전동기를 제작하고 과도 상태 시험을 수행하여 해석결과와 비교한다.

• Journal of computational fluids engineering
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• v.17 no.4
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• pp.103-109
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• 2012

Sound scattering in 3D complex geometry is difficult to model with body-fitted grid. Thus Brinkman Penalization method is used to compute sound scattering in 3D complex geometry. Sound propagation of monitor/TV is studied. The sound field for monitor/TV is simulated by applying Brinkman Penalization method to Linearized Euler Equation. Solid Structure and ambient air are represented as penalty terms in Linearized Euler Equation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.554-557
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• 2003

This paper describes the information for quantitative simulation of weakly ionized plasma. We should grasp the meaning of the plasma state condition to utilize engineering application and to understand materials of plasma state. In this paper, electron swarm parameter in He+Xe and Ar+He mixture gas calculated for range E/N values $0.01{\sim}500$ [Td] at the temperature is 300 [K] and pressure is 1 [Torr], using a set of electron collision cross sections determined by the authors, and using a method of Backward Prolongation by two term approximation Boltzmann equation method, for basic study on the gas discharge panel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.353-362
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• 2016

An accurate hysteresis model of an elastomer is important for quantifying viscoelastic energy loss. We suggest a highly nonlinear hyper-viscoelastic constitutive model of elastomers. The model captures a nonlinear viscoelastic characteristic by combining Yeoh's hyperelastic model and Hoofatt's hysteresis model used Neo-Hookean hyperelastic model. Analytical and numerical models were generated from uniaxial cyclic tests of an elastomer under a sinusoidal load with a mean strain of 150%, amplitudes of 20~80%, and frequencies of 0.02~0.2Hz. The viscoelastic model can highly capture the viscoelastic energy loss up to a strain of 230%.