• Journal of Korea Society of Industrial Information Systems
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• v.8 no.1
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• pp.9-17
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• 2003

The finite-difference time-domain (FDTD) method is used to analyze circular waveguide transformer in order to match different two waveguides. 2-dimensional cylindrical FDTD algorithm is applied for rotationally symmetric. The transformer is inserted at a circular-to-circular waveguide junction and two type transformers are proposed. One is a partially dielectric filled circular waveguide type and the other is filled a tapered circular dielectric rod. The numerical results are derived for various structure parameters, such as transformer length. dielectric diameter and waveguide diameter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.194-198
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• 2004

This paper presents a broadband compact microstrip antenna design with four U slots on the ground plane by using of genetic algorithm. FDTD method is used as fitness function for antenna analysis, and length of rectangular patch, length of ground plane slot, distance from center point to feed point is used as optimization parameter for maximum bandwidth and minimum size. The measurement result of implemented antenna present 10 dB bandwidth of 15.63 ％ and peak gain of 3.61 dBi in the 2.445 GHz, and antenna has a reduced patch size of 54.8 ％ compare with normal microstrip antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.108-114
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• 2012

We propose a dispersive finite-difference time domain(FDTD) algorithm suitable for the electromagnetic analysis of the human body. In this work, the dispersion relation of the human body is modeled by a quadratic complex rational function(QCRF), which leads to an accurate and efficient FDTD algorithm. Coefficients(involved in QCRF) for various human tissues are extracted by applying a weighted least square method(WLSM), referred to as the complex-curve fitting technique. We also presents the FDTD formulation for the QCRF-based dispersive model in detail. The QCRFbased dispersive model is significantly accurate and its FDTD implementation is more efficient than the counterpart of the Cole-Cole model. Numerical examples are used to show the validity of the proposed FDTD algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.667-673
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• 2000

This paper presents the modeling method of nonlinear circuits with lumped elements by using a hybrid Haar -wavelet MRTD/FDTD techniques. To analyze nonlinear circuits with lumped elements, the Haar-wavelet MRTD scheme is applied to the entire structure of interest and the conventional FDTD scheme is locally used to describe the characteristics of the lumped elements. To validate the scheme, microstrip structure with lumped elements and a single diode mixer are simulated.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.395-400
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• 2004

In this paper, the four-pole elliptic function microstrip filter at 2.4GHz band with fractional bandwidth of 4% is realized using compact miniaturized hairpin resonators. The parallel algorithm FDTD method is used to analyze S-parameter of hairpin resonator filter more accurately, and to calculate the electric coupling and magnetic coupling among the hairpin resonators. Absorbing boundary conditions for mesh termination used Sulivan's simplified PML and the FDTD code was paralleled by MPI for IBM SP2 which had enhanced calculation speed. The experimental measurements are performed by HP8720D vector network analyzer. Measured results on fabricated hairpin type cross coupled bandpass filters show good agreements with theoretic 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.

• Korean Journal of Remote Sensing
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• v.16 no.1
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• pp.65-72
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• 2000

Scattering coefficients of randomly rough lossy dielectric surfaces were computed by using the FDTD(Finite-Difference Time-Domain) method and the Monte Carlo method in this paper. The FDTD method was applied to compute electromagnetic wave scattering characteristics at any incident angles, any linear polarizations by dividing the computation region into the total-field region and the scattered-field region. The radar cross sections(RCS) of conducting cylinders have been computed and compared with theoretical results, measurement data and the results from the method of moment(MoM) to verify the FDTD algorithm. Then, to apply the algorithm to compute scattering coefficients of distributed targets, a two-dimensionally rough surface was generated numerically for given roughness characteristics. The far-zone scattered fields of 50 statistically independent dielectric rough surfaces were computed and the scattering coefficient of the surface was calculated from the scattered fields by using the Monte Carlo method. It was found that these scattering coefficients agree well with the SPM(Small Pertubation Method) model in its validity region.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1124-1131
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• 2011

In this paper, image reconstruction algorithm for breast cancer detection using MT(Microwave Tomography) was investigated. The breast cancer detection system under development uses 16 transmit/receive antennas. The signal waveform was a sinusoidal wave at 900 MHz. To solve the 2D inverse scattering problem, we used the 2D FDTD (Finite Difference Time Domain) method for forward calculation and LMA(Levenberg-Marquardt Algorithm) for optimization. The result of the image reconstruction using the numerical phantom by MRI(Magnetic Resonance Imaging) obtained from real patient of breast cancer showed that we can detect the position of the tumor accurately.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.1012-1018
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• 2016

We perform a electromagnetic analysis method for indirect effects of a high-conductive structure such as an aircraft exposed by lightning, by using the finite-difference time-domain(FDTD) method. The lightning waveform used to analyze indirect effects has low frequency spectrum and high-conductive materials such as aluminum and carbon fiber composite materials have very short skin depths, and thus, it requires large memory and long computation time using conventional three dimensional FDTD analysis method. We develop an efficient electromagnetic analysis method suitable for lightning and high-conductive structures. The developed analysis method is based on two dimensional FDTD and impedance network boundary condition(INBC) algorithms and we investigate the indirect effects on the structures exposed to lightning.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.21-28
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• 2015

In the semi-conductor process, a simulation process is performed to detect defects by analyzing the behavior of the impurity through the physical quantity calculation of the inner element. In order to perform the simulation, Finite-Difference Time-Domain(FDTD) algorithm is used. The improvement of semiconductor which is composed of nanoscale elements, the size of simulation is getting bigger. Problems that a processor such as CPU or GPU cannot perform the simulation due to the massive size of matrix or a computer consist of multiple processors cannot handle a massive FDTD may come up. For those problems, studies are performed with parallel/distributed computing. However, in the past, only single type of processor was used. In GPU's case, it performs fast, but at the same time, it has limited memory. On the other hand, in CPU, it performs slower than that of GPU. To solve the problem, we implemented a computing model that can handle any FDTD simulation regardless of size on the cluster which consist of heterogeneous processors. We tested the simulation on processors using MPI libraries which is based on 'point to point' communication and verified that it operates correctly regardless of the number of node and type. Also, we analyzed the performance by measuring the total execution time and specific time for the simulation on each test.