• International Journal of Railway
• /
• v.3 no.1
• /
• pp.14-18
• /
• 2010

This paper describes design and characteristic analysis of long primary type linear synchronous motor (LSM) for high speed train system. LSM is designed using loading distribution method and magnetic equivalent circuit. For characteristic analysis of LSM, analytical and numerical methods are applied. Analytical method for solving the magnetic field distribution of the analytic model is based on the Maxwell’s equations. Using the characteristic equation and magnetic equivalent circuit, we analyze the effect of variation of parameters, and then we validate the result by comparing with numerical method by finite element method (FEM). We compare the analytical method with numerical method for analyzing the effect by variable parameters. This result will be useful of design and forecast of performance without FEM.

• Journal of the Semiconductor & Display Technology
• /
• v.18 no.1
• /
• pp.87-91
• /
• 2019

As a highly conductive and transparent electrode, ITO/Ag/ITO multilayers are fabricated using an in-line sputtering method. Optimal thickness conditions have been investigated in terms of the optical transmittance and the electrical conductance. Considering the optical properties, in this study, the experimental characteristics are analyzed based on theoretical phenomena, and they are compared with the simulated results. The simulations are based on the finite-difference-time-domain (FDTD) method in solving linear Maxwell equations. Consequently, the results showed that ITO/Ag/ITO multilayer structures with respective thicknesses of 39.2 nm/10.7 nm/39.2 nm are most suitable with an average transmittance of about 87% calculated for wavelengths ranging from 400-800 nm and a sheet resistance of about $7.1{\Omega}/{\square}$.

• Structural Engineering and Mechanics
• /
• v.81 no.3
• /
• pp.335-348
• /
• 2022

It is well known that after finding the displacement in the structural mechanics, strain and stress can be obtained in the straight-forward process. The main purpose of this paper is to unify the displacement functions for solving the solid body. By performing mathematical operations, three sets of these key relationships are found in this paper. All of them are written in the Cartesian Coordinates and in terms of a simple function. Both analytical and numerical approaches are utilized to validate the correctness of the presented formulations. Since all required conditions for the bodies with self-equilibrated loadings are satisfied accurately, the authors' relations can solve these kinds of problems. This fact is studied in-depth by solving some numerical examples. It is found that a very simple function can be used for each formulation instead of ten different and complex displacement potentials defined by previous studies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.3
• /
• pp.284-290
• /
• 2016

As the recently advanced scientific developments result in high lever of the usability and the needs for the electrical equipment and devices in various situations, the safety technologies protecting malfunction and electrical critical damages including soft and hardware from the unexpectedly radiated electromagnetic interferences are required gradually. In addition, the numerical analysis for the miniaturized electrical components and equipments as well as the conventional electrical devices installed inside the electrically large enclosures and structures requires the memory requirement and time consumption too big to be handled in a realistic situation, which will result in a limitation in solving the complete set of maxwell's equations. In this paper, PWB method based on statistical theory and topological modeling with appropriate zoning concepts are introduced for the EM analysis of an electrically large complex structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.4
• /
• pp.1-6
• /
• 2005

The ability to predict radar return from flying vehicles becomes a critical technology issue in the development of stealth configurations. Toward developing a CEM code based on Maxwell's equations for analysis of RCS reduction schemes, an explicit upwind scheme suitable for multidisciplinary design is presented. The DFFT algorithm is utilized to convert the time-domain field values to the frequency-domain. A Green's function based on near field-to-far field transformation is also employed to calculate the bistatic RCS. To verify the numerical calculation the two-dimensional field around a perfectly conducting cylinder is considered. Finally results are obtained for the scattering electromagnetic field around an airfoil in order to illustrate the feasibility of applying CFD based methods to CEM.

• Steel and Composite Structures
• /
• v.42 no.6
• /
• pp.805-826
• /
• 2022

The free and live load-forced vibration behaviour of porous functionally graded (PFG) higher order nanobeams in the thermal and magnetic fields is investigated comprehensively through this work in the framework of nonlocal strain gradient theory (NLSGT). The porosity effects on the dynamic behaviour of FG nanobeams is investigated using four different porosity distribution models. These models are exploited; uniform, symmetrical, condensed upward, and condensed downward distributions. The material characteristics gradation in the thickness direction is estimated using the power-law. The magnetic field effect is incorporated using Maxwell's equations. The third order shear deformation beam theory is adopted to incorporate the shear deformation effect. The Hamilton principle is adopted to derive the coupled thermomagnetic dynamic equations of motion of the whole system and the associated boundary conditions. Navier method is used to derive the analytical solution of the governing equations. The developed methodology is verified and compared with the available results in the literature and good agreement is observed. Parametric studies are conducted to show effects of porosity parameter; porosity distribution, temperature rise, magnetic field intensity, material gradation index, non-classical parameters, and the applied moving load velocity on the vibration behavior of nanobeams. It has been showed that all the analyzed conditions have significant effects on the dynamic behavior of the nanobeams. Additionally, it has been observed that the negative effects of moving load, porosity and thermal load on the nanobeam dynamics can be reduced by the effect of the force induced from the directed magnetic field or can be kept within certain desired design limits by controlling the intensity of the magnetic field.

• Structural Engineering and Mechanics
• /
• v.88 no.2
• /
• pp.159-168
• /
• 2023

Cost-effective high precision hybrid elements are presented in a hierarchical form for dynamic analysis of plates. The costs associated with controlling the vibrations of ferromagnetic plates can be minimized by adequate determination of the amount of electric current and magnetic field. In the present study, the effect of magnetic field and electric current on nonlinear vibrations of ferromagnetic plates is investigated. The general form of Lorentz forces and Maxwell's equations have been considered for the first time to present new relationships for electromagnetic interaction forces with ferromagnetic plates. In order to derive the governing nonlinear differential equations, the theory of third-order shear deformations of three-dimensional plates has been applied along with the von Kármán large deformation strain-displacement relations. Afterward, the nonlinear equations are discretized using the Galerkin method, and the effect of various parameters is investigated. According to the results, electric current and magnetic field have different effects on the equivalent stiffness of ferromagnetic plates. As the electric current increases and the magnetic field decreases, the equivalent stiffness of the plate decreases. This is a phenomenon reported here for the first time. Furthermore, the magnetic field has a more significant effect on the steady-state deflection of the plate compared to the electric current. Increasing the magnetic field and electric current by 10-times results in a reduction of about 350% and an increase of 3.8% in the maximum steady-state deflection, respectively. Furthermore, the nonlinear frequency decreases as time passes, and these changes become more intense as the magnetic field increases.

• Journal of the Korean Magnetics Society
• /
• v.25 no.4
• /
• pp.129-137
• /
• 2015

The Cu(radius ra = $95{\mu}m$)/$Ni_{80}Fe_{20}$(outer radius $r_b$ = $120{\mu}m$) core/shell composite wire is fabricated by electrodeposition. The two diagonal components of impedance tensor for the Cu/$Ni_{80}Fe_{20}$ core/shell composite wire in cylindrical coordinates, $Z_{zz}$ and $Z_{{\theta}{\theta}}$, are measured as a function of frequency in 10 kHz~10 MHz and external static magnetic field in 0 Oe~200 Oe. The equations expressing the diagonal $Z_{zz}$ and $Z_{{\theta}{\theta}}$ in terms of diagonal components of complex permeability tensor, ${\mu}^*_{zz}$ and ${\mu}^*_{{\theta}{\theta}}$, are derived from Maxwell's equations. The real and imaginary parts of ${\mu}^*_{zz}$(f) and ${\mu}^*_{{\theta}{\theta}}$(f) spectra are extracted from the measured $Z_{zz}$(f) and $Z_{{\theta}{\theta}}$(f) spectra, respectively. It is presened that the extraction of ${\mu}^*_{zz}$(f) and ${\mu}^*_{{\theta}{\theta}}$(f) spectra from the diagonal impedance spectra can be a versatile tool to investigate dymanic magnetization process in the core/shell composite wire.

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

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.3
• /
• pp.39-51
• /
• 2012

The time-dependent characteristics of mudstone in this study were analyzed by performing creep tests for the mudstone in Pohang. The creep tests were conducted on various boundary conditions to observe the time-dependent behavior of mudstone and the results were compared with values predicted by established visco-elastic model and empirical equations. As a result of analysis for empirical equations proposed by Griggs(1936), Cottrell(1952) and Singh(1975), the creep constants generally tend to increase as increasing the stress level and water content. Moreover, the values predicted by Singh's equation were well fitted for the test results. Therefore, it is expected to be reasonable that creep behavior of mudstone is analyzed using Singh's equation. As a result of analysis for a Burger's model, the predicted values were well fitted for the test results. Therefore, it is expected be reasonable that the creep behavior of mudstone by a rheological model is analyzed using Burger's model.