• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.890-894
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• 2006

To make the best use of known characteristics of the alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method such as unconditional stability and modeling accuracy, an efficient time domain solution with variable time-step size is proposed. Numerical experiment shows that a time-step size for a given mesh size can be increased preserving a desired numerical accuracy over frequencies of interest. The proposed method can be used to analyze electromagnetic problems with reduced computation time.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.34-44
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• 1996

N-machine produces more than input energy at above 3000 rpm. any space energy is absorbed when the N-machine is rotating at a very high velocity. Laws of electromagnetics verify that normal conduction is due to that electrons moves from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next. The ${\pi}-far$ infrared rays are generated from the resonance and rotation of the electrons on the orbitals of three-dimensional crystallizing ${\pi}-bonding$ atoms. Material in universe is composed of ${\pi}-rays$, which have alternative outward electric field. If the alternative outward electric fields of the ${\pi}-rays$ are resonant each other they make attraction force, which is the gravity. The collection of space energy is due to a attraction force between the radially alternating electric field and the ${\pi}-far$ infrared rays in the space. Electrons flow by absorbed density difference of ${\pi}-far$ infrared rays along a conduction wire, which also verifies that normal electron conduction is due to a flow from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.641-646
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• 2015

In this paper, a zinc electrowinning cell is fully optimized to achieve a uniform current distribution at electrode surfaces. To effectively deal with an electromagnetically coupled problem with multi-dimensional design variables, a sampling-based sensitivity approach is combined with a highly tuned multiphysics simulation model. The model involves the interrelation between electrochemical reactions and electromagnetic phenomena so as to predict accurate current distributions in the electrowinning cell. In the sampling-based sensitivity approach, Kriging-based surrogate models are generated in a local window, and accordingly their sensitivity values are extracted. Such unique design strategy facilitates optimizing very complicated multiphysics and multi-dimensional design problems. Finally, ten design variables deciding the electrolytic cell structure are optimized, and then the uniformity of current distribution in the optimized cell is examined through the comparison with existing cell designs.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.175-183
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• 2016

This paper brings out a novel method for reducing Near end and Far end Crosstalk using Electromagnetic Band Gap structures (EBG) in High Speed RF transmission lines. This work becomes useful in high speed closely spaced Printed Circuit Board (PCB) traces connected to multi core processors. By using this method, reduction of −40dB in Near-End Crosstalk (NEXT) and −60 dB in Far End Crosstalk (FEXT) is achieved. The results are validated through experimental measurements. Time domain analysis is performed to validate the signal integrity property of coupled transmission lines.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.403-405
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• 2003

An iterative Green's function method (IGFM) is introduced to analyze complex electromagnetic waveguide structures in view of the university student. The IGFM utilizes the Green's function and iteration scheme. The physical mechanism with simple mathematical equations is used to formulate the IGFM. Scattering characteristics of a standard E-plane T-junction in a parallel-plate waveguide are theoretically investigated in terms of the IGFM. Numerical computations illustrate the characteristics of resection and transmission powers versus frequency. A dominant-mode solution is presented and compared with the higher-mode solutions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.250-254
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• 2008

Eddy currents are induced when a nonmagnetic conductive material is moving subjected to the magnetic field due to a permanent magnet. These currents circulates in the conductive material and are dissipated, causing a repulsive force between the magnet and the conductor. Using this concept, the eddy current damping can be used as a viscous damping. The present study investigates the characteristics of a magnetic damping analytically and experimentally. The theoretical model of a eddy current damping is developed from electromagnetics and is verified from experiments. The drop test of a magnet in the cooper tube shows that the present model can accurately predict the damping force. Additionally, the dynamic test of a eddy current damping is carried to verify the present model.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.2
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• pp.81-85
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• 2005

This paper presents some interesting results regarding the harmonic performance on the photonic band-gap (PBG) structures formed by periodic conducting vias. Study on PBG structures has been one of the major topics in electromagnetics, microelectronics, and communications areas. In most of the studies, the band-gap filtering behavior was fulfilled by a periodic pattern of perforations on the ground planes of microstrip lines. Nevertheless, the PBG characteristics can also be realized using a periodic via-pattern along the transmission-line circuits. Hence, some of the via-typed PBG structures are studied and their frequency characteristics in terms of the scattering parameters are presented. It is found that by varying the length of vias with respect to the period pattern, different harmonic performances are observed.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2568-2570
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• 2004

CEMTool is a command style design and analyzing package for scientific and technological algorithm and a matrix based computation language. In this paper, we present new FEM (Finite Element Method) package in CEMTool environment. In contrast to the existing MATLAB PDE Toolbox, our proposed FEM package can deal with the combination of the reserved words. Also, we can control the mesh in a very effective way With the introduction of new mesh generation algorithm and NDM (Hosted Dissection Method), our FEM package can guarantee the shorter computational time than MATLAB PDE Toolbox. In addition, using the advanced electromagnetics library of CEMTool FEM package, we can analyze the practical problems such as the motor field analysis. Consequently, with our new FEM package, we can overcome some disadvantages of the existing MATLAB PDE Toolbox.

• ETRI Journal
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• v.34 no.4
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• pp.536-541
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• 2012

This paper aims to extend the transmission line matrix method with a hybrid symmetrical condensed node (HSCN) to model ferrite media in the time domain. To take into account the anisotropy and dispersive properties of ferrite media, equivalent current sources are incorporated into supplementary stubs of the original HSCN. The scattering matrix of the proposed HSCN is provided, and the validity of this approach is demonstrated for both transversely and longitudinally magnetized ferrites. Agreement is achieved between the results of this approach and those of the theoretical and the finite-difference time-domain method.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.78-82
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• 2010

An integrated multi-disciplinary design system plays a critical role in the preliminary design of an aircraft. In this paper such system is developed for the multi-disciplinary computation and design; aerodynamics elasticity, and radio frequency stealth. Common data base of geometry and structured grids is generated and used for aerodynamic, structural and eletromagnetics analysis. The Navier-Stokes CFD, FEM, and CEM technique are used for aerodynamic, structural, and RF stealth computations respectively.