• Proceedings of the KIEE Conference
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• summer
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• pp.785-787
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• 2004

The purpose of this paper is characteristic analysis of permanent magnet generator for AVR power of brushless synchronous generator. However, the PMG has a spoke type rotor with overhang, so we perform the analysis considering overhang for the precise airgap flux density. In this paper, dynamic analysis model with 2D FEM considering overhang is proposed by use of 2D, 3D static FEM results. The proposed method is verified by the results of PMG load test.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.324-326
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• 2000

A 3D magnetostatic field is analyzed considering the non-linear characteristics of the material using finite element method. In the finite element formulation, the edge element is adopted since it reduces the required computer memory and the computing time. The modified Newton-Raphson method is also used for non-linear analysis. A numerical example with the TEAM workshop problem 13 is analyzed, and the results are proved to concide well with measured ones.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.70-76
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• 2006

The microstructure evolution during a hot forging of Waspaloy was investigated using the recrystallization model and FEM simulation. In order to obtain an uniform microstructure, hot forging was carried out by two step. The change of grain size during hot forging has a deep connection with dynamic recrystallization behavior. Avrami-type constitutive equation for the dynamic recrystallization was implemented into an user subroutine of 2D FE simulator. The evolution of grain structure in the two-step forging of Waspaloy was simulated using the 2D FEM user-subroutine. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.631-635
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• 1995

Longitudinal magnetic recording process of thin film media was simulated by the 2-D finite element method (FEM). To describe precisely the hysteresis behavior of thin film media, scalar Preisach model was used. In this paper, we discussed the formation of bit patterns and importance of modeling of minor loops in high density recording. The effects of the media coercivity and film thickness on the remanent magnetization and transition shape were investigated.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.58-65
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• 2019

A 3D FEM (Finite Element Method) based Helmholtz solver has been commonly used to characterize fundamental acoustic behavior and investigate dynamic instability features in many combustion systems. In this approach, a geometrical simplification of the target system has been generally made in order to reduce computational time and cost because a real combustor and fuel nozzle have a very complicated flow passage. The feasibility of these simplifications is quantitatively investigated in a small aero gas turbine nozzle in term of acoustic characteristics. It is found that the simplification in a nozzle geometry during the 3D FEM analysis process has no great influence on the acoustic modeling results, while the calculation complexity can be improved for a similar modeling accuracy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.237-245
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• 2011

Asphalt Plug Joint(APJ) is a new type of expansion joint that it's application are increased in USA as well as several European countries. APJ's' advantages are cheap construction and maintenance costs, and simple construction and securing of excellent flatness. However, APJ's usability is hindered because it showed a problem of premature failure. Research for solving this problem has been progressed, and FEM analysis among existing researches was peformed. However, the behavior of APJ was insufficiently analyzed and the reliability of the analysis was much low, since the material showing complicated behavior was oversimplified, Therefore, a material model was proposed and its effectiveness was confirmed by comparing it with actual behavior in order to improve the reliability of FEM analysis in this paper. ABAQUS program was used for FEM analysis, and an elasto-plastic model and a viscous-plastic model as the material model of APJ were suggested on the base of experiment results of APJ material performed by Bramel et al. The elasto-plastic model was defined by time-independent analysis since it didn't consider time and strain rate, and the viscous-plastic model was defined by time-dependent analysis since it considered. Influence of various elements affecting the behavior of APJ was investigated, and it was confirmed that the time-dependent analysis showed better result closed to actual behavior than the time-independent analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.373-376
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• 2006

The ring rolling design for a large-scale Ti-6Al-4V alloy ring was performed with a calculation method and FEM simulation. The ring rolling design includes geometry design and optimization of process variables. The calculation method was to determine geometry design such as initial billet and blank size, and final rolled ring shape. A commercial FEM code, SHAPE was used to simulate the effect of process variables in ring rolling on the distribution of the internal state variables such as strain, strain rate and temperature. In order to predict the forming defects during ring rolling, the process-map approach based on Ziegler's instability criterion was used with FEM simulation. Finally, an optimum process design to obtain sound Ti-6Al-4V rings without forming defects was suggested through combined approach of Ziegler's instability map and FEM simulation results.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.661-666
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• 2007

최근들어 제품을 개발하는 과정 중, 디자이너와 개발자, 의사 결정권자들이 FEM, CFD 시뮬레이션 결과를 리뷰할 때에 가상현실기술을 도입하는 사례가 늘고 있다. 몰입감을 높여주는 가상현실환경은 모델에 대한 해석 결과물을 정확하고 효과적으로 분석할 수 있도록 돕는다. 데이터의 실제 크기와 같게 혹은 그보다 더 크고 자세한 이미지를 제공하는 가상현실 몰입환경은 사용자가 데스크탑 환경만을 사용할 때 경험할 수 없는 높은 사실감을 제공함으로써 사용자에게 시각적인 만족감을 줄 수 있다. 하지만 데스크탑 환경에 비해 해상도가 낮고, 어두운 곳에서 스테레오 안경이나 HMD(Head Mounted Display), Data glove등을 착용해야 하는 불편함과 멀미, 시각적인 피로, 방향감각 상실로 대표되는 가상멀미 등으로 인해 장시간 사용에 어려움이 있다. 데스트탑 환경에서의 데이터 리뷰는 고해상도 이미지 분석은 가능하지만, 입체감이 떨어지기 때문에 리뷰 데이터의 실제감이 떨어진다. 이와 같은 문제점들을 보완하기 위해서 본 논문에서는 데스크탑 환경과 가상현실 환경 간의 협업이 가능한 FEM/CFD 가시화 시스템을 제시한다. 본 시스템은 가상현실 몰입환경에서 해석 데이터를 단순히 가시화하는 것뿐만이 아니라, 데스크탑 시스템과 동일한 3D 인터페이스 구조를 제공한다. 따라서, 해석 결과 분석을 위한 동일한 post-processing 작업이 네트워크로 연결된 원격 공간의 사용자들이 사용하는 시스템들 사이에서 실시간으로 진행될 수 있다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.252-257
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• 2016

Dust-collecting behavior of tonpilz transducer was simulated with finite-element-method (FEM) software. In order to optimize the performance of tonpilz transducer, the shape factors including the thickness of head mass, the diameter of tail mass and the depth of bolt were analyzed as variables. As a vibrating energy source, the piezoelectric materials was also tested with PZT-4 and two kinds of piezoelectric single crystals. The output power of the transducer was maximized with the shape factors and then the behavior of the dust-collection was demonstrated with the multi-physics software, COMSOL.

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.172-177
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• 2007

The process design for large-scale ring rolling of Ti-6Al-4V alloy was performed by calculation method, processing map approach and FEM simulation. The ring rolling design includes geometry design and optimization of process variables. The calculation method was used to make geometry design such as initial billet and blank sizes, and final rolled ring shape. A commercial FEM code, SHAPE-RR was used to simulate the effect of process variables in ring rolling on the distribution of the internal state variables such as strain, strain rate and temperature. In order to predict the forming defects during ring rolling and the formation of over-heating above $\beta$-transus temperature due to deformation heating, the process-map approach based on Ziegler's instability criterion was used with FEM simulation. Finally, an optimum process design to obtain sound Ti-6Al-4V rings without forming defects was suggested through combined approach of Ziegler's instability map and FEM simulation results.