• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.17 no.3
• /
• pp.139-170
• /
• 2013

We extend a p-hierarchical decomposition of the second degree finite element space of N$\acute{e}$d$\acute{e}$lec for tetrahedral meshes in three dimensions given in [1] to meshes with hexahedral elements, and derive p-hierarchical decompositions of the second degree finite element space of Raviart-Thomas in two dimensions for triangular and quadrilateral meshes. After having proved stability of these subspace decompositions and requiring certain saturation assumptions to hold, we construct a local a posteriori error estimator for fem and bem coupling of a time-harmonic electromagnetic eddy current problem in $\mathbb{R}^3$. We perform some numerical tests to underline reliability and efficiency of the estimator and test its usefulness in an adaptive refinement scheme.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.5
• /
• pp.233-241
• /
• 2003

Geotextile tube is hydraulically filled with dredged materials and has been applied to coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. In this paper, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of geotextile sheet and hydraulic pumping conditions. Numerical analysis was executed to compare with the results from the large-scale field model tests, and also with those of plane strain analysis and 3-D FEM analysis. A geotextile tube was modeled using the commercial finite element analysis program ABAQUS and the one-quarter of tube was modeled. Behavior of geotextile tube during the hydraulic pumping procedure was analyzed by comparing the large-scale field model test and numerical analysis. The shape variation and maximum tube height between the numerical analysis results and large-scale filed test results are turned out to be in a good agreement.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.831-832
• /
• 2006

본 논문에서는 Brushless DC Motors(이하 BLDC Motor이라 함)의 영구 자석의 오버행에 따른 진동, 소음 특성에 대하여 다루었다. 비대칭 오버행 구조에서는 Z축 방향 힘이 발생한다. 이는 베어링에 손상을 입힐 뿐 아니라 큰 노이즈와 진동을 유발시킨다. 따라서 진동과 소음의 감소를 위한 자석 오버행 효과 해석이 필수적이다. 본 논문에서는 비대칭 영구 자석 오버행 효과를 해석하고 BLDC Motor에서 발생하는 소음과 진동을 분석하였고 비대칭 영구 자석 오버행 효과를 고려하여 Z축 방향의 영향력을 계산하기 위하여 3차원 유한요소법(3D FEM)을 사용하였다.

• Advances in materials Research
• /
• v.3 no.1
• /
• pp.237-257
• /
• 2014

In this paper, we adopted a two-dimensional analytical electro-elastic model to predict the stress distributions of the piezoelectric actuator in 3D case. The actuator was embedded in an elastic host structure under electrical loadings. The problem is reduced to the solution of singular integral equations of the first kind. The interfacial stresses and the axial normal stress in both plane stress state and plane strain state were obtained to study the actuation effects being transferred from the actuator to the host. The stress distributions of the PZT actuator in different length and different thickness were analyzed to guarantee the generality. The validity of the present model has been demonstrated by application of specific examples and comparisons with the corresponding results obtained from the Finite Element Method.

• Progress in Superconductivity and Cryogenics
• /
• v.11 no.3
• /
• pp.60-64
• /
• 2009

We investigated an operating characteristic of linear-type magnetic flux pump (LTMFP) as a current compensator under the various conditions. In order to explain the mechanism of the LTMFP, the magnetic behavior of superconducting Nb foil according to pumping actions should be understood. In this paper, the magnetic field analysis of superconducting Nb foil installed in LTMFP has been performed based on the three-dimensional finite element method (3D FEM). Through the simulation analysis, the normal spot region on the superconducting Nb foil is found to be enhanced swiftly over about 20 Hz. The simulated finding agreed with an analytical estimation based on the phenomenon of magnetic diffusion.

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

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.2
• /
• pp.93-102
• /
• 1995

A series of test was performed by measuring the failure strength and the failure mode of fiber reinforced composite laminates joint containing two holes in Series or Parallel. $[0^{\circ}/45^{\circ}/90^{\circ}/-45^{\circ}]_s$ laminate with W/d(Side distance ratio) 4.0 and E/d(Edge distance ratio) 3.0 has the full bearing strength and are preferable in case of the good efficiency in two series hole. Comparisons were made between testing results and predicting values of the FEM model. Good agreements were fecund between them except the case of $E/d=2{\sim}3$. In the case of $G_h{\geq}3.0d$ and $G_v{\geq}3.0d$ since the interaction coefficients between two parallel holes and between two series holes were small, holes can be treated as independent. The Acoustic Emission(AE) and SEM method were utilized to find out the initial defects, damage and the fracture mechanism.

• Journal of Electrical Engineering and Technology
• /
• v.1 no.2
• /
• pp.211-215
• /
• 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.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.2
• /
• pp.123-128
• /
• 2005

This paper presents an analysis of the permanent magnet overhang effect for the permanent magnetic actuator. Generally, the overhang is often used to increase the force density in permanent magnet machineries. The overhang is particularly profitable in reducing the volume after increasing the force density per volume when using the overhang effect of the permanent magnet. Therefore, the 3D Equivalent Magnetic Circuit Network Method (3D EMCN) has been used in this paper. According to the plunger position, the flux distribution per overhang length and the holding force are quantitatively compared. Furthermore, an appropriate length of the overhang has been proposed. To confirm the accuracy of the analysis method, the results of 2D FEM and 3D FEM are compared for the basic model.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.4
• /
• pp.399-404
• /
• 2013

The rotor overhang is used to enhance air-gap flux and improve power density. Due to asymmetry in the axial direction caused by the overhang, the time consuming 3D analysis is necessary to design the motor with overhang. To solve this problem, this paper proposes the equivalent magnetic circuit model (EMCM) that can consider overhang effects without the 3D analysis by using effective air-gap length. The analysis time can be reduced significantly via the proposed EMCM. The reduction of the analysis time is essential for the preliminary design of the motor. In order to verify the proposed model, the 3-D finite-element method (FEM) analysis is adopted. 3-D FEM results confirm the validity of the proposed EMCM.