• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.8-16
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• 2006

In this paper, updating schemes for the alternating-direction implicit finite-difference time-domain method(ADI-FDTD) are studied, which method has the potential to considerably reduce the number of time iterations especially in case where the fine spatial lattice relative to the wavelength is used to resolve fine geometrical features. In numerical simulations for microwave structure using ADI-FDTD, time marching scheme comprises of two sub-iterations. Two different updating equation sets for ADI-FDTD simulations are presented. In order to discuss the characteristics of those schemes especially in view of applying boundary conditions, we solved two complementary 2-D problems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.584-590
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• 2003

In this paper, the numerical characteristics of the recently developed Envelope ADI-FDTD are investigated. Through numerical simulations, it is shown that the unconditional stability of the Envelope ADI-FDTD is independent of time step size and we can get better dispersion accuracy than the traditional ADI-FDTD by analyzing the envelope of the signal. This fact gives the opportunity for extending the temporal step size to the Nyquist limit in certain cases. Numerical results show that the Envelope ADI-FDTD can be used as an efficient electromagnetic analysis tool especially in the single frequency or band limited systems.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.88-92
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• 2020

As a highly conductive and transparent electrode, the optical transmittances of ITO/Ag/ITO were simulated and compared with the experimental results. The simulations are based on the finite-difference time-domain (FDTD) method in solving linear Maxwell equations. In our simulations, the computation domain is set in the XZ-plane with 3D dimension, and a plane wave with variable wavelengths ranging from 250 nm to 850 nm is incident in the z-direction at normal incidence to the ITO/Ag/ITO film surrounded by free-air space. As the results through both simulations and experiments, it was shown that the thickness combinations by the ITO layers of about 40 nm and the Ag layer of about 10 nm could be most suitable conditions as a high conductive transparent electrode having the transmittance similar to that of a single ITO layer.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.32-37
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• 2005

We developed a numerical simulator in order to study the Super-RENS/ROM (Super REsolution Near-Field Structure, Read Only Memory) using 3-dimensional FDTD (finite difference time domain) method. The simulation can be performed by three steps. In the first step, we utilized the vector-diffraction theory to calculate the characteristics of incident laser beam from the object-lens to the surface of the disk. At the second step, we fed the calculated result as an input for the main FDTD simulations on the optical layers in the disk structure. After performed the FDTD simulations, we took near-to-far field transformation for the reflected signal, from the surface of the disk to the detector. Finally, we can get reflected signal at the photo-diode. Using this developed simulator, we were able to study about the reading signal from various disk structures as a function of a laser beam position. We calculated reading signals for various pit sizes for Super-ROM structure, and it is found that the simple optical diffraction theory can not explain the reading mechanism of Super-ROM, and more complicated temperature dependent physics must be involved.

• Transactions of the Society of Information Storage Systems
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• v.2 no.2
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• pp.138-143
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• 2006

We developed a numerical simulator in order to study the Super-RENS/ROM (Super REsolution Near-Field Structure, Read Only Memory) using 3-dimensional FDTD (finite difference time domain) method. The simulation can be performed by three steps. In the first step, we utilized the vector-diffraction theory to calculate the characteristics of incident laser beam from the object-lens to the surface of the disk. At the second step, we fed the calculated result as an input for the main FDTD simulations on the optical layers in the disk structure. After performed the FDTD simulations, we took near-to-far field transformation for the reflected signal, from the surface of the disk to the detector. Finally, we can get reflected signal at the photo-diode. Using this developed simulator, we were able to study about the reading signal from various disk structures as a function of a laser beam position. We calculated reading signals for various pit sizes for Super-ROM structure, and it is found that the simple optical diffraction theory can not explain the reading mechanism of Super-ROM, and more complicated temperature dependent physics must be involved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.407-415
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• 2011

The stability condition and wideband characteristics of 3D ID-FDTD algorithm which has low dispersion error with isotropic dispersion are presented in this paper. 3D ID-FDTD method was proposed to improve the defect of the Yee FDTD such as the anisotropy and large dispersion error. The published paper calculated the stability condition of 3D ID-FDTD algorithm by using numerical method, however, it is thought that the examples were not sufficient to verify the stability condition. Thus, in this paper, various simulations are included in order to hold reliability under the conditions that the plane wave propagation is assumed with a single frequency and a wideband frequency. Also, the 3D ID-FDTD algorithm is compared to those that have the similar FDTD algorithm with ID-FDTD such as Forgy's method and non-standard FDTD method in a wideband. Finally, the radar cross section(RCS) for the large sphere with high dielectric constant is calculated.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.373-376
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• 2000

Coplanar-type MIS transmission lines have been simulated using FDTD method and compared with the measured results and the simulated results of the reference paper［3］. We can confirm that our simulation results are similar to measured results compared to the previous simulated results of the reference paper. Moreover, variations of characteristic impedance by insulator thickness are calculated for the insulator thickness of 0.0,0.5 and 1.0$\mu\textrm{m}$.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.145-148
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• 1998

In this paper, a microstrip antenna is designed using a rectangular patch. To find characteristics of the antenna, computer simulations of the rectangular single microstrip patch antenna are performed with changing width. And we compared the result of computer simulation with the experimental value. Through the results, we found that the 3-D FDTD method is an effective method for designing microstrip patch antenna. According to simulation the resonant point has been found it in the frequency received from GPS satellite. It is thought that make it match by adjusting the feedpoint.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.113-117
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• 2002

최근 산란함수의 곱셈전개에 근거를 둔 새로운 공명 산란이론이 개발되어 공명성분의 크기와 위상을 수치적으로 정확하게 얻게 해 주었다. 또한 음파분야에서는 공명스펙트럼을 얼기 위해 MIIR 라는 실험방법을 개발되어 사용하여 왔다. 본 논문에서는 원통형 유전체에 의한 산란장 문제에 공진 산란이론을 적용하여 공진 주파수를 얻고, MIIR 의 실험 모델에 수치 해석방법인 FDTD를 적용하여 이로부터 역으로 유전율 등에 관한 정보를 얻기 위한 산란장 스펙트럼을 예측하였다.

• ETRI Journal
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• v.46 no.2
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• pp.333-346
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• 2024

Various techniques for noninvasively focus microwave energy on lesions have been proposed for thermotherapy. To focus the microwave energy on the lesion, a focusing parameter, which is referred to as the magnitude and phase of microwaves radiated from an external array antenna, is very important. Although the finite-difference time-domain (FDTD)-based time-reversal (TR) focusing algorithm is widely used, it has a long processing time if the focusing target position changes or if optimization is needed. We propose a technique to obtain multistatic data (MSD) based on Green's function and use it to derive the focusing parameters. Computer simulations were used to evaluate the electric fields inside the object using the FDTD method and Green's function as well as to compare the focusing parameters using FDTD- and MSD-based TR focusing algorithms. Regardless of the use of Green's function, the processing time of MSD-based TR focusing algorithms reduces to approximately 1/2 or 1/590 compared with the FDTD-based algorithm. In addition, we optimize the focusing parameters to eliminate hotspots, which are unnecessary focusing positions, by adding phase-reversed electric fields and confirm hotspot suppression through simulations.