• Interaction and multiscale mechanics
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• 제6권2호
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• pp.237-255
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• 2013

In this paper, a meshfree-enriched finite element method (ME-FEM) is introduced for the large deformation analysis of nonlinear path-dependent problems involving contact. In linear ME-FEM, the element formulation is established by introducing a meshfree convex approximation into the linear triangular element in 2D and linear tetrahedron element in 3D along with an enriched meshfree node. In nonlinear formulation, the area-weighted smoothing scheme for deformation gradient is then developed in conjunction with the meshfree-enriched element interpolation functions to yield a discrete divergence-free property at the integration points, which is essential to enhance the stress calculation in the stage of plastic deformation. A modified variational formulation using the smoothed deformation gradient is developed for path-dependent material analysis. In the industrial metal forming problems, the mortar contact algorithm is implemented in the explicit formulation. Since the meshfree-enriched element shape functions are constructed using the meshfree convex approximation, they pose the desired Kronecker-delta property at the element edge thus requires no special treatments in the enforcement of essential boundary condition as well as the contact conditions. As a result, this approach can be easily incorporated into a conventional displacement-based finite element code. Two elasto-plastic problems are studied and the numerical results indicated that ME-FEM is capable of delivering a volumetric locking-free and pressure oscillation-free solutions for the large deformation problems in metal forming analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.421-422
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• 2012

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1112-1119
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• 2011

The goal of this study is the stability evaluation of a vacuum pump through modal test and rotor dynamics. Roots type vacuum pump, which is a dry vacuum pump, is necessary for the manufacturing process of the semiconductor and the display. Eigenvalue was solved by the finite-element method(FEM) using 2D and 3D models, then the modal test result was compared with the FEM result. According to the comparison, the analysis result using the 2D was more accurate than the 3D model. Therefore, rotor dynamics was performed by the 2D model. Campbell diagram and root-locus maps, which were calculated by complex-eigenvalue analysis, were used to evaluate the stability of the rotors of the vacuum pump. And displacement solved by unbalance response analysis was compared with the minimum clearance between two rotors of the vacuum pump. Thus, the vacuum pump is assumed operated under steady state through the evaluation of the rotor dynamics.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.699-703
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• 2018

Flux-switching permanent magnet machines (FSPMM) have doubly-salient and simple structures making it cost effective and suitable for mass production. In addition, it is possible to increase the rotor rotating speed and concentrate the flux of the permanent magnet on the air-gap. Due to these merits, the FSPMM can be applied to the various industry applications. To improve the performance, various design variables need to be studied in terms of design techniques. In this paper, we especially concentrate on the distribution of iron losses using a two-dimensional finite-element method (2D FEM). As a result, we can get an information for high efficiency FSPMM design.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.617-624
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• 1999

The spiral type thin-film inductor performed in high frequency at 2-5[MHz] range is analyzed by 2-dimensional Finite Element Method(2D FEM). The features of micro thin-film inductor have complicated electromagnetic phenomenon such as skin effect, proximity effect and magnetic saturation. To develope miniatured magnetic device considering these features, it is important to predict the property of the thin film inductor according to design parameter. In this paper, we present the 2D FEM analysis for the spiral type thin film inductor. The characteristics of inductor from point of view of inductance, resistance and quality factor are studied according to design parameter and various pattern construction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.107-109
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• 2003

본 논문은 전력기기 중 저압 재폐로(Recloser) 차단기에 대한 FEM을 이용한 조작부 구동메커니즘의 동작특성에 대해 연구하였다. 중 저압 차단기는 크게 차단부와 조작부로 분리할 수 있는데 조작부메커니즘은 동작특성의 영향을 많이 받기 때문에 차단동작특성이 좋고 신뢰성 및 반복성이 우수한 영구자석형 마그네틱 액추에이터를 사용하였다. 그리고, 정확한 동작 특성 해석을 위해 물질의 비선형 특성을 고려하였고, 외부회로와 결합하여 2-D FEM을 통한 전자계 해석을 하였다. 또한, 실험을 통한 최종적인 기계적인 힘과 FEM으로 해석한 액추에이터의 힘을 비교 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.36-38
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• 1995

A Single-phase condensor motor is analyzed by FEM coupled with external circuit. The finite element analysis is based on the solution of combined equation both the magnetic field equation from the Maxwell's and the circuit equations of the stator and rotor circuit. The external circuit of the single-phase condensor motor to be analyzed is described using FLUX2D and linked to multiple FEM regions. The simulated results show that the condensor motor analysis with external circuit has good agreement with those of test results.

• 인터넷정보학회논문지
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• 제24권2호
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• pp.27-36
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• 2023

도파관(waveguide)은 전자기파를 원하는 방향으로 안내하는 전송선로로 의료기기, 레이더 시스템, 위성 통신 등 다양한 분야에 활용되고 있다. 이러한 도파관의 설계 및 최적화를 위해서는 전자기 수치해석(CEM: Computational Electromagnetics)이 필수적이다. 수치해석 기법의 하나인 유한요소법(FEM: Finite Element Method)은 도파관과 같은 닫힌 영역 내부의 전자기 문제를 해결하는데 효율적이며 이를 적용하기 위해서는 계산영역을 한정시키기 위한 경계조건이 필요하다. 본 논문에서는 계산영역 밖으로 나가는 전자파의 반사를 최소화하기 위한 흡수경계조건(ABC: Absorbing Boundary Condition)과 주 모드 뿐만 아니라 고차 모드까지 흡수할 수 있는 도파관 포트 경계조건(WPBC: Waveguide Port Boundary Condition)을 각각 적용하여 2/D 및 3/D 도파관 구조에 대한 전자기 시뮬레이션을 수행하였다. 이후, 대표적인 전자파 상용 소프트웨어인 HFSS와의 결과 비교를 통해 해석의 정확성을 검증하였으며, 시뮬레이션 결과를 통해 WPBC를 적용하면 ABC보다 더 작은 해석 영역으로 구조 해석이 가능하다는 것을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.211-215
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• 2006

This paper presents a new structure for the universal motor using soft magnetic composite (SMC). The stator for this new type of motor is made by combination of the SMC pole and the silicon steel yoke. The shape of the 3D SMC pole is designed to minimize ohmic loss and amount of stator coil. To design the pole shape, the 3D analysis in the design procedure is replaced with an equivalent 2D analysis. Finally, the optimal shape is analyzed by 3D FEM and the performance is discussed.

• 한국생산제조학회지
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• 제19권1호
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• pp.42-49
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• 2010

In general, the direct experimental approach to study machining processes is expensive and time consuming, especially when a wide range of parameters are included: tool, geometry, materials, cutting conditions, etc. The aim of this study is to verify the effectiveness of finite element method for orthogonal cutting process by comparing the simulated cutting forces with measured results. Two commercialized finite element codes $AdvantEdge^{TM}$ and Deform-$2D^{TM}$ have been used to simulate the cutting forces in orthogonal cutting process. In this paper, estimated cutting and feed force components are compared with experimental results for different two materials. As a result, it has been found that FEM simulation is effective for understanding and predicting the orthogonal cutting process although some improvements on friction model and remeshing process are needed.