• 전기학회논문지
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• 제56권7호
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• pp.1231-1235
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• 2007

This paper presents the dynamic characteristics of a linear brushless dc (BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. Dynamic performance of the linear BLDC motor driven with 6 step inverter such as thrust force and speed is simulated by finite element method coupling with external circuit and measured for the prototype motor. The results of finite element analysis are compared to the experimental results and verify reliability.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권1호
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• pp.22-26
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• 2005

This paper proposes the calculation method of magnetic coupling coefficient of the contactless energy transmission system by 3D finite element method with a variation of the secondary core positions. The primary, secondary self and leakage inductances and the capacitances of a resonant circuit are calculated by the finite element analysis results. From these values, the magnetic coupling coefficients are obtained. The secondary voltages and currents according to the secondary core positions are calculated by using the resonant circuit and compared.

• 대한의용생체공학회:의공학회지
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• 제29권4호
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• pp.267-271
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• 2008

The RF shimming technique has been used to improve the transmit RF field homogeneity in highfield MRI. In the RF shimming technique, the amplitude and phase of the driving currents in each coil element are optimized to get homogenous flip angle or uniform image intensity. The inductive and capacitive coupling between the coil elements may degrade the RF field homogeneity if not taken into account in the optimization procedure. In this paper, we have analyzed the coupling effects on the RF shimming using a sixteen-element TEM RF coil model operating at 300 MHz. We have found that the coupling effects on the RF shimming can be reduced by putting high dielectric material between the active rung and the shield.

• 한국통신학회논문지
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• 제18권11호
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• pp.1767-1773
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• 1993

본 논문에서는 probe로 급전되는 적층형 마이로스트립 2소자 배열 안테나의 임피던스 및 결합특성을 제시하였다. 안테나 구조의 해석에는 벡터 한켈 변환을 이용한 스팩트럴 영역법을 적용하였다. 또한 이 안테나의 임피던스 및 결합특성, 그리고 두 소자 안테나간의 거리에 따른 결합특성 변화등을 측정하여 그 결과를 제시한다. 끝으로, 해석을 통해 계산된 결과와 측정된 결과를 비교하여 두 결과가 잘 일치함을 보였다.

• Interaction and multiscale mechanics
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• 제2권4호
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• pp.353-374
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• 2009

A new seamless multiscale simulation was developed for coupling the continuum model with its molecular dynamics. Kriging-based Finite Element Method (K-FEM) is employed to model the continuum base of the entire domain, while the molecular dynamics (MD) is confined in a localized domain of interest. In the coupling zone, where the MD domain overlaps the continuum model, the overall Hamiltonian is postulated by contributions from the continuum and the molecular overlays, based on a quartic spline scaling parameter. The displacement compatibility in this coupling zone is then enforced by the Lagrange multiplier technique. A multiple-time-step velocity Verlet algorithm is adopted for its time integration. The validation of the present method is reported through numerical tests of one dimensional atomic lattice. The results reveal that at the continuum/MD interface, the commonly reported spurious waves in the literature are effectively eliminated in this study. In addition, the smoothness of the transition from MD to the continuum can be significantly improved by either increasing the size of the coupling zone or expanding the nodal domain of influence associated with K-FEM.

• 한국정보통신학회논문지
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• 제9권2호
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• pp.415-421
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• 2005

어레이 소자의 방사 또는 수신 특성은 소자 상호결합 효과 때문에 고립된 소자의 특성과 달라지게 되며, 따라서 어레이 성능은 고립된 소자를 가정하여 설계할 경우의 성능과 다르게 된다. 접지판 위에 위치한 삼각형 격자 구조를 가진 직사각형 다이폴 어레이에 미치는 상호 결합의 영향을 소자패턴을 고려하여 논의하였다. 소자 이득 함수를 이용하여 소자가 균일하게 분포되거나 소자간격이 체감된 어레이에서 부엽(sidelobe)에 미치는 소자 상호결합 효과의 영향을 점검하였다. 상호결합 효과가 존재할 때, 소자간격이 체감된 어레이에서의 부엽의 성능이 소자간격이 균일하게 분포된 어레이와 비교하여 향상되는 것을 보여주었다. 컴퓨터 시뮬레이션을 제시하였다.

• 한국지진공학회논문집
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• 제21권6호
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• pp.303-310
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• 2017

The coupled shear wall system with coupling beams is an efficient structural system for high-rise buildings because it can provide excellent ductility and energy dissipation to the buildings. The objective of this study is to simulate the hysteretic behavior of diagonally reinforced concrete coupling beams including pinching and cyclic deteriorations in strength and stiffness using a numerical model. For this purpose, coupling beams are modeled with an elastic beam element and plastic spring element placed at the beam ends. Parameters for the analytical model was calibrated based on the test results of 6 specimens for diagonally reinforced concrete coupling beams. The analytical model with calibrated model parameters is verified by comparing the hysteretic curves obtained from analysis and experimental tests.

• 소성∙가공
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• 제17권3호
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• pp.189-196
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• 2008

Alloy718 is the nickel-base super alloy well used as gas turbine components under severe operating conditions because of its high strength at high temperature and excellent creep resistance. In this study, a coupling bolt for the gas turbine component is manufactured by hot heading process instead of whole machining in order to improve the mechanical properties. Die shape for the hot heading has been designed by general design rule of hot forging and also optimal process condition has been investigated by finite element method. The initial billet temperature and the punch speed have been determined by $1150^{\circ}C$ and 600mm/s on the basis of finite element analysis, respectively. The coupling bolt has been manufactured by 200ton screw press and evaluated by experiment in order to investigate the mechanical properties. As a result of experiment, the mechanical properties such as hardness, tensile strength and creep behavior have been superior to those manufactured by machining.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.409-410
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• 2011

• 한국음향학회지
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• 제31권3호
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• pp.142-150
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• 2012

도파관유한요소법 (waveguide finite element method, WFEM)은 단면의 형상이 길이방향으로 일정한 도파관 구조물의 진동을 해석하기 위한 수치해석 기법이다. 도파관유한요소법은 2차원 단면만을 FE 모델링하여 길이방향 파동 전파를 해석하므로 기존의 유한요소법에 비해 해석 모델의 크기가 작고 연산 시간이 짧다는 장점을 가진다. 본 연구에서는 기존의 도파관유한요소법을 확장하여 내부 및 외부에 유체가 채워진 도파관 구조물에 대한 진동 해석을 수행하였다. 이를 위해 내부 유체와 도파관 구조물은 WFE로, 외부 유체는 파수경계요소 (waveguide boudnary element, WBE)로 모델링하고 이들을 연성시킨 운동방정식을 제시하였다. 이 방법의 적용 예로써 내부에 물이 채워진 몰수된 파이프의 진동 및 방사 음향 파워를 해석하였다. 내부 및 외부 유체의 유/무에 따른 분산 선도와 가진점 모빌리티 (point mobility)를 구하고 유체 연성의 효과를 살펴보았다.