• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.709-711
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• 2006

According as optical storage becomes high-density, numerical aperture increases. Therefore, the shift characteristic of moving parts in an actuator for optical pickup becomes a critical design factor because of decrease in the tilt margin. The tilt angle is maximized when the position of moving parts is in a diagonal direction within a moving range. This is determined by design of structure and magnetic circuit of an actuator. Previous analysis method only predicts linear characteristics of moving parts. However, the result of shift characteristics of the moving parts considering structural and magnetic circuit's nonlinearity following the every position simultaneously shows us more realistic result. Therefore, we present analysis method considering nonlinearity of moving parts' position through FEM package using coupled-field analysis. Then, we will suggest hereafter a design guide by comparing the above results with experimental ones.

• 한국정밀공학회지
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• 제21권12호
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• pp.140-145
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• 2004

In this study, the design and analysis of a butterfly valve disk was performed to minimize the rubbing between the disk and the seat at opening and closing. The butterfly valve has double eccentric structure and the contact surface between the disk and the seat is a conical surface. At the instant of opening and closing the valve by the rotation of disk, the positions of zero contact point are changed. Also, if the cone surface is cut in the perpendicular direction to the rotation axis of the valve, the contour of cutting section is hyperbolic. Therefore minimum distance between the origin of the eccentric axis and the hyperbolic curve goes to the position of zero contact point. In order to consider the interferences between the disk and the seat, the thermal-structure coupled field analysis was performed by ANSYS.

• Structural Engineering and Mechanics
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• 제63권4호
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• pp.481-495
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• 2017

The present article examines the static response of multilayered magneto-electro-elastic (MEE) beam in thermal environment through finite element (FE) methods. On the basis of the minimum total potential energy principle and the coupled constitutive equations of MEE material, the FE equilibrium equations of cantilever MEE beam is derived. Maxwell's equations are considered to establish the relation between electric field and electric potential; magnetic field and magnetic potential. A simple condensation approach is employed to solve the global FE equilibrium equations. Further, numerical evaluations are made to examine the influence of different in-plane and through-thickness temperature distributions on the multiphysics response of MEE beam. A parametric study is performed to evaluate the effect of stacking sequence and different temperature profiles on the direct and derived quantities of MEE beam. It is believed that the results presented in this article serve as a benchmark for accurate design and analysis of the MEE smart structures in thermal applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.323-325
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• 1995

An Inductively Coupled Plasma(ICP) was employed to prepare the Diamond-Like Carbon film with $CH_4$ gas. We observed the changes of mechanical, optical properties and internal stress of the films according to the variation of discharge power and negative-self bias. When weak magnetic field is applied, the properties of film are observed to change drastically. In magnetized case, the micro-hardness and the internal stress increase up to critical point and droped down in marked contrast to unmagnetized case. It suggests that large amount of ion flux exists due to high dissociation rate of the reactive radicals in plasma with magnetic field as reported elsewhere. As a result of FT-IR absorption measurement it could be confirmed that the $CH_x$ bonding and the micro-hardness and the internal stress decreased with the increase of negative-self bias.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1117-1119
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• 1999

An edge finite element method is applied to calculate the field distribution of a coupled waveguide structure. We compares a node based finite element method with the edge element one. For 2-d eigenvalue problems of waveguide structures, the former generates spurious eigenmodes, but the latter dose not. Using an simple rectangular waveguide, we implement both methods to obtain some results of field computation in waveguide. The paper shows that the finite element method using edge elements succeeds in suppressing spurious solutions.

• Journal of Magnetics
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• 제3권3호
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• pp.89-91
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• 1998

The magnetisation behaviour of polycrystalline permalloy/copper multilayers with mixed antiferromagnetic/ferromagnetic coupling was investigated as function of temperature. The results are discussed in a framework of a realistic model of anitferromagnetically coupled layers connected by ferromagnetic pinholes. A microstructure of pinholes (their density and dimensions) was varied either by a proper annealing treatment or by choosing samples with various Cu spacer thicknesses. It was demonstrated that the temperature changes of the net magnetic moment measured in a magnetic field smaller than the saturation field was strongly affected by the composition of the pinholes, their density, cross-sectional area and their lengths.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권3호
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• pp.159-164
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• 2000

This paper treats the optimization of rotor construction in the permanent magnet synchronous motor (PMSM) for electric vehicle (EV). While the field system of PMSM has generally one magnet per pole, we replace the magnet into plural sub-magnets. The dimensions of each sub-magnet are determined by the concept of pulse width modulation (PWM). By adopting the proposed rotor construction, we can not only reduce the space harmonics of the air-gap field but also provide space for rotor bars (i.e., damper windings) around the direct-axis. From the investigation by hybrid EE-BE (coupled finite element and boundary element) method coupled with both electric circuit and motion equation, we verify that the construction is effective for practical use.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.39-51
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• 2014

This paper deals with design of a direct-coupled, small-scaled permanent magnet generator (PMG) for wind power application. First, this paper determines rated power and speed of the PMG from measured characteristics of wind turbines. Second, we derive analytical solutions for the open-circuit field in order to determine optimum magnet thickness and pole pitch/arc ratio. Third, on the basis of open circuit field solutions, stator magnetic circuit including slot opening, teeth width and yoke thickness is designed. And then, a diameter of stator coil which agree with a required current density is calculated, and its turns are determined from the area of slot considering winding packing factor. Finally, finite element (FE) method is employed in analyzing the details of the designed PMG and, test results such as back-emf measurements are given to confirm the design.

• Journal of the Optical Society of Korea
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• 제1권2호
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• pp.94-99
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• 1997

In this paper, we calculate the four coefficients for the quantum theory of multiwave mixing including a local-field correction resulting from dipole-dipole interactions. We make contact with the semiclassical calculations of probe absorption and four-wave-mixing coupling coefficients, and illustrate the effects of local field corrections on resonance-fluorescence and coupled-mode-fluorescence spectra. The method uses the hybrid quantum-Langevin-equation master-equation approach of An and Sargent.

• 대한수학회지
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• 제58권5호
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• pp.1131-1145
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• 2021

In this article, we study the Klein-Gordon-Maxwell equations arising from a semilocal gauge field model. This model describes the interaction of two complex scalar fields and one gauge field, and generalizes the classical Klein-Gordon equation coupled with the Maxwell electrodynamics. We prove that there exist infinitely many standing wave solutions for p ∈ (2, 6) which are radially symmetric. Here, p comes from the exponent of the potential of scalar fields. We also prove the nonexistence of nontrivial solutions for the critical case p = 6.