• Journal of Magnetics
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• v.21 no.1
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• pp.110-114
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• 2016

Magnetic couplings are widely used in various industrial applications because they can transmit magnetic force without any mechanical contact. In addition, linear couplings have many advantages. For example, they do not need to convert rotary motion to linear motion. This paper shows an analytical analysis of tubular type linear magnetic couplings (TLMCs) with a Halbach array magnetized permanent magnet (PM). An analytical method for magnetic fields owing to PMs is performed by using magnetic vector potential as well as Poisson and Laplace equations. Then, the magnetic force is calculated by using the Maxwell stress tensor. The analytical analysis results were compared with finite element method (FEM) results. In addition, we predicted the magnetic force characteristic according to design parameters such as the iron core thickness, inner PM thickness to -outer PM thickness ratio, PM segment ratio of the axial magnetized PM segment and radial magnetized PM segment, and various pole numbers.

• Smart Structures and Systems
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• v.20 no.6
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• pp.729-737
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• 2017

Piezoelectric composite laminates are a powerful material system that offers vast options to improve structural behavior. Successful design of piezoelectric adaptive structures and testing of control laws call for highly accurate, reliable and numerically efficient numerical tools. This paper puts focus onto linear and geometrically nonlinear static and dynamic analysis of smart structures made of such a material system. For this purpose, highly efficient linear 3-node and 4-node finite shell elements are proposed. Both elements employ the Mindlin-Reissner kinematics. The shear locking effect is treated by the discrete shear gap (DSG) technique with the 3-node element and by the assumed natural strain (ANS) approach with the 4-node element. Geometrically nonlinear effects are considered using the co-rotational approach. Static and dynamic examples involving actuator and sensor function of piezoelectric layers are considered.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1596-1603
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• 2018

This paper presents the new design and validation process of the linear transverse flux machine of the stelzer machine for hybrid vehicle application. A linear transverse flux machine is a novel electric machine that has higher force density and power than conventional electric machine. The process concentrates on 2-dimensional and 3-dimensional analysis using equivalent magnetic circuit method considering leakage elements and it is verified by finite element analysis. Besides the force characteristics of all axis of each direction are analyzed. The study is considered by dividing the transverse flux electric excited type and the transverse flux permanent magnet excited type. Additionally three-dimensional analysis in this machine is accomplished due to asymmetric structure with another three axes. Finally, it suggests the new design and validation process of linear transverse flux machine for stelzer machine.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.1
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• pp.129-135
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• 1998

The characteristic of load-distribution is investigated by using nonlinear analysis with a field loading test of existing bridge In this study, nonlinear load-distribution technique for quantitative analysis was adopted. The results were compared with linear solution technique with data from failure test at existing RCT-girder bridge and examine the adequacy of the failure mode. The results of this study showed that the linear solution technique and the proposed nonlinear solution technique agreed well in linear region but did not matched well in nonlinear region because of load-redistribution, and that the effect of load-redistribution was considered to analysis of nonlinear region by linear solution.

• Structural Engineering and Mechanics
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• v.10 no.4
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• pp.393-404
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• 2000

Linear stress analysis without body force can be easily solved by means of the boundary element method. Some cases of linear stress analysis with body force can also be solved without a domain integral. However, domain integrals are generally necessary to solve the linear stress problem with arbitrary body forces. This paper shows that the linear stress problem with arbitrary body forces can be solved approximately without a domain integral by the triple-reciprocity boundary element method. In this method, the distribution of arbitrary body forces can be interpolated by the integral equation. A new computer program is developed and applied to several problems.

• Journal of Magnetics
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• v.16 no.1
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• pp.46-50
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• 2011

This paper presents size reduction of primary iron core for tubular linear induction motor by improved winding configuration. Using one-ampere conductor method, magnetic field analysis of tubular linear induction motor for size reduction is conducted. Size reduction and improvement of air gap flux distribution is achieved by improved winding configuration, and analysis results are verified by finite element analysis (FEA) and experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.983-986
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• 2005

Free vibration characteristics of a curved pipe conveying fluid is studied when the pipe is clamped at both ends. Using the perturbation method, the non-linear governing equations divided into two parts; the steady state non-linear equilibrium equations and the linearized equations of motion in the neighborhood of the equilibrium position. The natural frequencies are computed from the linearized equations of motion. In this study, the equilibrium positions are determined by two types of equations, i.e., (1) the non-linear equations, and (2) the equations obtained by neglecting the non-linear terms. The natural frequencies obtained from the non-linear equilibrium equations are compared to those obtained from the linearized equilibrium equations. From the results, as the fluid velocity increases, the equilibrium position should be determined from the nonlinear equations for the vibration analysis of the curved pipe conveying fluid.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.229-233
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• 2009

This paper proposes a correction method for the error inherently created by time-step approximation in finite element analysis (FEA). For a simple RL and RLC linear circuit, the error in time-step analysis is analytically investigated, and a correction method is proposed for a non-linear system as well as a linear one. Then, for a practical inductor model, linear and non-linear time-step analyses are performed and the calculation results are corrected by the proposed methods. The accuracy of the corrected results is confirmed by comparing the electric input and output powers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.731-734
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• 2001

A cryogenic stirling cooler is currently under development at Korea Institute of Industrial Technology(KITECH). Cryocooler has many kinds of types. The stirling cooler is the most appropriate one for under 80K with the trait of long life cycle and small size. The stirling cooler uses helium as a working fluid. Helium is pressurized by the linear compressor which is driver by linear motor. In this paper, the change of pressure and volume is studied by the isothermal analysis method. It is necessary to investigate the optimized pressure to meets the highest COP. The compressor's piston and expender's displacer interact according to the working fluid's pressure level and the phase difference. This paper presents the relation between the initial pressure and the work of cryocooler. By that results, we can predict the performance of linear compressor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.2
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• pp.53-58
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• 2001

This paper describes a moving mesh technique for dynamic characteristics analysis of permanent magnet linear synchronous motor with the secondary aluminium sheet. The moving mesh technique applied to the linear induction motor can be used to analyze the linear synchronous motor with the rectangular permanent magnet. But in case of the permanent magnet with taper, the shape of the permanent magnet is presented. The time-stepped finite element method is used for the dynamic characteristics simulation of the permanent magnet linear synchronous motor, The results of application example(hysteresis current controlled inverter fed control) such as thrust, current and flux plots are shown.