• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.794-795
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• 2015

This paper deals with back-EMF characteristic comparison of Vertical and Halbach array double-sided linear generator with coreless type. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetic modeling is predicting characteristic analysis by using the Fourier series expansion. And then, we obtained magnetic field solutions and calculated resistance, back-EMF constant. The analytical results used by 2-D cylindrical coordinate system. The analytical method used in this paper is confirmed by comparing with finite element analysis results.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.127-129
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• 1988

Square-wave current source inverter drives suffer from torque pulsation and speed variation at low speed. Attempts to minimize these problems, CSI PWM strategies have been reported. It is shown that these PWM strategies are based on unnecessarily restrictive modulation laws. In this paper, trapezoidal PWM strategy for CSI is investigated theoratically by double fourier series and we proposed Harmonic Speed ripple Factor(HSF) that is independent of motor parameters and load conditions. Speed ripple are considered in T-PWM and square wave inverter by HSF. We obtain modulation index(M) and carrier ratio (CR) for minimum speed ripple.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.234-237
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• 1997

In the Closing time in order to operate synchronous generators parallely, it is generated the asynchronous phenomena. These asynchronous phenomena give rise of the eddy current on the rotor. These eddy current are solved analytically for the Laplace' Equ. ${\nabla}^2{\widetilde{H}}=0$ in free space and for the Bullard's Equ. ${\nabla}^2{\widetilde{H}}$+${\sigma}_r{\mu}_r{\nabla}$${\times}$${\widetilde{\nu}}_r$${\times}$${\widetilde{H}}^{III}$=${\sigma}_r{\mu}_r{\frac{{\partial}H}{{\partial}t}}$ for the rotor by using each double Fourier series component of the 3D H-field

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2684-2693
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• 1993

The free vibration and dynamic response of cross-ply for CFRP and GFRP laminated circular cylindrical shells under dynamic loadings are investigated by using the first-order shear deformation shell theory. The modal analysis technique is used to develop the analytical solutions of simply supported cylindrical shells under dynamic load. The analysis is based on an expansion of the loads, displacements and rotations in a double Fourier series which satisfies the and boundary conditions of simply support. Analytical solution is assumed to be separable into a function of time and a function of position. In this paper, the considered load forces are step pulse, sine pulse, triangular(1, 2, 3) pulse and exponential pulse. The solution for a given loading pulse can be found by involving the convolution integral. The results show that the dynamic response are governed primarily by the natural period of the structure.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.4
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• pp.407-416
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• 1991

A turbogenertor without damper cage is divided into five regions according to compoding materials in the radial direcrion. And the electric and magnetic field of each region in the subsynchronous resonance (SSR) phenomena is analyzed in this paper. The analytical method is based on solving a boundary value problem involving a three-dimensional magnetic diffrsion equation and the basic function consists of the double Fourier series. And the electrical characteristics of the material and kthickness of the wedges inserted in slot of the region III, which is dependent on frequency, is to be investigated.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.443-455
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• 2001

An energy method has been used for an elastic formulation of bending vibration and buckling analysis of laminated composite plates on two-parameter elastic foundations. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates. The third-order shear deformation theory is applied by using the double-fourier series. To validate the derived equations the obtained displacements for simply supported orthotropic plates on elastic foundations are compared with those of LUSAS program Numerical results of the viscoelastic bending vibration and buckling analysis are presented to show the effects of layup sequence number of layers material anisotropy and shear modulus of foundations.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.333-340
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• 1997

This paper will expand the third-order shear deformation theory by the double-Fourier series and reduce to the solution of a system of ordinary differential equations in time, which are integrated numerically using Newmark's direct integration method and clarify the undamped dynamic responses for the cross-ply and antisymmetric angle-ply laminated composite plates and shells with simply supported boundary condition. Numerical results for deflections are presented showing the effect of side-to-thickness ratio, aspect ratio, material anisotropy, and lamination scheme.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.103-114
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• 1992

A study result of buckling reliability is presented for the axially compressed imperfect elastic cylinder. Multi-mode analysis program is developed from Karman-Donnell Equation for the calculation of the buckling load of the cylindrical she1l. Geometric intial imperfection is approximated by double Fourier series of which coefficients are assumed random variables with jointly normal distribution characteristics. Crude Monte Carlo simulation technique is used to calculate the probabilistic failure properties of several cases with various imperfection Conditions.

• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.58-65
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• 2015

This paper deals with the generating characteristic analysis of permanent magnet linear generator (PMLG) with double-sided Halbach magnet array mover and three phases concentrated stator windings by using analytical method. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetization modeling for Halbach magnet array is performed analytically by using the Fourier series. And then, we obtain electrical parameters such as back-EMF constant, resistance, and coil inductance based on magnetic field calculations. Finally, analytical results for generating performance are confirmed by comparing with finite element analysis results.