• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.68-75
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• 2000

In this paper, we analyzed the radiation patterns of a monopole antenna mounted on cylinder and EM penetration problems in the complex structures by using FDTD method associated with 3-D PML absorbing boundary condition. In order to validate the proposed FDTD code, the radiation patterns of monopole antenna mounted on cylinders were compared with the exact Carter's solutions. As a results, the predicted radiation pattern exhibited excellent agreement with exact solution. And the FDTD code is applied to analyze the EM penetration problems in complex structures, Blackhawk helicopter. As the plane wave is excited, a significant amount of energy penetrates the helicopter structure, and it is dependent on aperture/airframe interface.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.106-115
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• 2010

Because of space limitations, interferences between antennas of the KSLV-I communication systems occur and their effects become worse during all sorts of tests such as the flight test using a light plane. In this paper, coupled signal magnitude is calculated using the FDTD method. The theory of the FDTD, absorbing boundary condition, source input technique, and post processing of data are explained. The calculated coupling factor between two IFAs, which have 2 GHz resonance frequency and placed 5 cm apart, is -12.7 dB. Applied coupling calculation method can be effectively used for KSLV-I performance analysis, subsystem design, antenna arrangement, and communication link budget for the next space launch vehicle.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.664-673
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• 2007

In this paper, the ID-FDTD scheme, proposed in Reference [1] and [2], is modified and completely analyzed. The modifications are composed of three parts: rigorous stability analysis, dispersion relation for linear lossy media, and new scaling factors for permittivity, permeability, and conductivity. As a result, it is shown that the proposed scheme has lower dispersion error in spite of larger time step than the conventional standard scheme of Reference [3]. To validate the scheme, there are presented two scattering examples, which show excellent results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.748-751
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• 2013

We perform a wideband radiated pulse coupling analysis of simple building structures using the finite-deference time-domain(FDTD) method. Toward this purpose, the building structures composed of concrete and window materials are assumed and we numerically model the electrical properties of each material. In this work, we apply a dispersive FDTD algorithm for the electromagnetic analysis of building structures and investigate their shielding effectiveness in the frequency range of 50 MHz to 1 GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.183-186
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• 2005

A two dimensional (2-D) finite-difference time-domain (FDTD) method based on a novel finite difference scheme is developed to eliminate the numerical dispersion errors. In this paper, numerical dispersion and stability analysis of the new scheme are given, which show that the proposed method is nearly dispersionless, and stable for a larger time step than the standard FDTD method.

• Journal of electromagnetic engineering and science
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• v.8 no.4
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• pp.139-143
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• 2008

In this paper, a new scheme to calculate the weighting factor of the 2-D isotropic-dispersion finite difference time domain(ID-FDTD) is proposed. The weighting factor in [1] was formulated in free space, so that it may not be optimal in dielectric media. Therefore, the weighting factor was reformulated by considering the material properties and using the least mean square method. As a result, a minimum numerical dispersion error for any dielectric media is guaranteed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.141-149
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• 2009

In this paper, quasi-static FDTD method is implemented by FORTRAN programming, and it is used for analysis of body induced current in middle frequencies. The quasi-static FDTD program is validated by comparing the calculation result with analytic solution of the test model, to which it is difficult to apply conventional FDTD. It is confirmed that the time-step is reduced by $5.68{\times}10^6$ times. Using validated numerical technique, body induced current distribution in high resolution 3-D human model is calculated for 20[kHz] magnetic field exposure and 1[MHz] electric field exposure. Also, the effect of grounding condition of both feet on the distribution and amplitude of the induced current is analyzed. It is expected that this research can be applied to various fields including safety assessment of body induced current and development of diagnosis devices using bio-electricity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.191-198
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• 2011

In this paper, a method to approximate a multi-layer Green's function is proposed based on a FDTD scheme and a rational function approximation. For a given horizontal propagation wavenumber, time domain response is calculated and then Fourier transformed to the spectral domain Green's function. Using the rational function approximation, the pole and residue of the Green's function can be estimated, which are crucial for a calculation of a path loss. The proposed method can provide a wideband Green's function, while the conventional normal mode method can be applied to a single frequency problem. To validate the proposed method, We consider two problems, one of which has a analytical solution. The other is about multi-layer case, for which the proposed method is compared with the known normal mode solution, Kraken.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1165-1172
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• 2008

In this paper, the scattering parameters of the metamaterial slab are obtained using the 2D FDTD(Finite-Difference Time-Domain) method. FDTD method is one of strongest electromagnetic numerical method which is widely used to analyze the metamaterial structure because of its simplicity. But it is very difficult to obtain frequency response of metamaterial itself because frequency dispersive model such as Lorentz, Drude model are used in FDTD. We used the well-known m-n-m cycle sine pulse to obtain the frequency response of the metamaterials. Comparisons between the wideband Gaussian input pulse and band-limited m-n-m cycle sine pulse are performed in this paper also. From the results, we concluded that the scattering parameters in frequency domain can be obtained using specific input pulse in FDTD even if the response has valid only for limited bandwidth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.67-69
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• 2012

In this paper, electromagnetic scattering analysis of Fresnel Lens by using 2D FDTD method was performed. Fresnel lens which is consigured 7 diffracted conductors, and considered at 5GHz. As a result, axial gain characteristic corresponding to near design focusing distance at 0.71m is 26dB.