• Journal of Digital Contents Society
• /
• v.10 no.3
• /
• pp.389-393
• /
• 2009

In this paper, the single patch microstrip antenna and gap coupled broadband microstrip patch antenna using FDTD(Finite Difference Time Domain method) are analyzed. Mur's 2nd absorbing boundary condition to minimize reflected wave is applied. Return loss, voltage standing wave ratio, and input impedance by the length and width of driving patch, the length and width of parasitic patch, and the distance between driving patch and parasitic patch have been analyzed. Design parameters and radiation patterns of broadband antenna have been also shown.

• Geophysics and Geophysical Exploration
• /
• v.20 no.3
• /
• pp.121-128
• /
• 2017

Interpretation of time-domain electromagnetic (TEM) data has been made mostly based on one-dimensional (1-D) inversion scheme in Korea. A proper interpretation of TEM data should employ 3-D TEM forward and inverse modeling algorithms. This study developed a 3-D TEM modeling algorithm using a finite difference time-domain (FDTD) method with staggered grid. In numerically solving Maxwell equations, fictitious displacement current is included based on an explicit FDTD method using a central difference approximation scheme. The developed modeling algorithm simulated a small-coil source configuration to be verified against analytic solutions for homogeneous half-space models. Further, TEM responses for a 3-D anomaly are modeled and analyzed. We expect that it will contribute greatly to the precise interpretation of TEM data.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.2 no.4
• /
• pp.653-660
• /
• 1998

The purpose of this paper is to analyze the electromagnetic field characteristics of microstrip array antenna with the FDTD(finite difference-time domain method). Finite difference equations of Maxwell's equations are defined in rectangular coordinate systems. To simulate the unbounded problem like a free space, the Mur's absorbing boundary condition is also used. After modeling the microstrip array antenna with the grid structure, the transient response of the field distribution is depicted in the time domain.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.6 no.4
• /
• pp.11-19
• /
• 1995

In this paper, the Finite Difference Time Domain (FDTD) method is used to analyse the characteristics of the coaxial line transmission coefficent, shielding effectiveness, and compared to results of the moment method. The excitation mode of the Gaussian pulse is assumed to be a TEM-mode instead of the TE or TM-mode and in order to eliminate the reflected wave with in short length of the line. Calculated value of shielding effectiveness of the coaxial line by the FDTD are in good agreement with the results of the moment method.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.181-184
• /
• 2012

기존에 제시된 Lin 과 Liu (1999)의 VOF 기법을 이용한 내부 조파 방법을 레블셋 기법에 적용하였다. 기하학적으로 유리한 유한요소법을 이용하여, Navier-Stokes 방정식의 공간차분에는 Characteristic Galerkin 기법을, 시간차분에는 Fractional Four-Step 기법을 적용하였다. 그림에 보인 바와 같이 중심(x=0)에서 전파하는 경우, 외부조파에 의한 영역내 재반사 문제가 해결되어 선형파를 의도한 바대로 잘 조파할 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.6
• /
• pp.761-767
• /
• 1998

The Perfectly Matched Layer(PML) provide good performance in absorption over a wide frequency range and is an appropriate ABC for waveguides with high dispersion. In this paper, a novel algorithm is proposed to improve the computational efficiency of the PML. In the input and output ports, the fields are decomposed into a series of modes, and then an appropriate ABC is applied to each mode. CPU time and memory storage requirements are greatly reduced, since the computational region is analyzed in one dimension. A WG-90 rectangular waveguide with a thick asymmetric iris is analyzed by Finite-Difference Time-Domain(FDTD) simulations with the conventional PML and the proposed one-dimensional (1-D) PML. Numerical results show that the computational efficiency is significantly improved by the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.1
• /
• pp.38-44
• /
• 2010

In this paper, the higher order FDTD(Finite-Difference Time-Domain) method is used to obtain the frequency response characteristics of the cylindrical metamaterial slab. FDTD method is one of strongest electromagnetic numerical method which is widely used to analyze the metamaterial structure because of its simplicity and the dispersive FDTD equation which has the dispersive effective dielectric constant and permeability are derived to analyze the metamaterials. This derived dispersive FDTD equation has no errors in analyzing the dielectric materials but there are some time and frequency errors in case of analyzing the metamaterials. We used the higher order FDTD method to obtain the accurate frequency response of the metamaterials. Comparisons between the dispersive FDTD method and the higher order FDTD method are performed in this paper also. From the results, we concluded that more accurate frequency response for various metamaterials applications can be obtained using the proposed method in this paper.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.5 no.4
• /
• pp.30-39
• /
• 1994

The resonant frequency, reflection cofficient and input impedance of a microstrip transverse dipole coupled electromagnetically are calculated using Finite Difference Time Domain(FDTD) method, and the evolution of gaussian pulse and spatial distribution of electromagnetic field components in the computation domain is represented graphically. Also, we confirmed the computation results show good agreement with the results of Method of Moment(MOM) and experiment[8] reported in the literature.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1634-1638
• /
• 2008

하천의 2차원 흐름 해석, 유사이동 해석, 오염확산 해석을 위한 유체의 수치해석법에는 유한요소법, 유한차분법, 유한차분법의 변형인 유한체적법, 경계적분법 등이 있다. 유체에 대한 수치해석 기법으로 전통적으로 가장 많이 사용되고 있는 방법은 유한차분법이지만, 비구조적 요소망(unstructured mesh)을 이용하여 복잡한 형상을 표현하기가 상대적으로 용이한 유한요소법이 다양한 형태의 하천 해석에는 더욱 적합할 것이다. 본 연구에서는 비구조적 요소망을 advanced front method를 이용하여 생성해 보았다. Advanced front method는 해석하고자 하는 영역에 적절한 절점들을 생성한 후 삼각 요소망을 구성하는 grid based advanced front method와 절점들을 생성하지 않고 해석 영역에 삼각 요소를 바로 구성하는 element based advanced front method로 나눌 수 있다. Grid based advanced front method에서 해석 영역에 적절한 절점을 생성하는 방법으로는 일반적인 격자 구조의 절점 생성 방법을 적용하였으며 경계와의 거리가 가까운 절점은 생성되지 않으며, 삼각 요소를 구성할 때에는 두 개의 인접 절점을 비교하여 최적의 삼각 요소를 구성하게 된다. 단 두 개의 인접 절점만을 비교함으로서 비교적 빠른 시간 안에 최적의 삼각 요소망을 구성할 수 있다. 삼각 요소망을 생성한 후에는 Laplacian smoothing을 이용하여 삼각 요소망의 형질을 개선하였다. Element based advanced front method는 외부 경계에서부터 시작된 Front가 내부 영역으로 확대되어지며 각 Front에서 적절한 절점을 직접 생성하여 바로 삼각 요소를 구성하게 된다. Front에서 생성된 절점은 인접 절점들이 있는지 검색하여 인접 절점이 있다면 생성된 절점은 삭제되어지며 인접 절점이 삼각 요소를 위한 나머지 한 점으로 채택되어진다. Front는 외부 경계와 교차되어지지 않아야 하며 또한 연속된 Front를 효율적으로 관리하기 위해 list 자료 구조를 활용하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.2 s.105
• /
• pp.165-170
• /
• 2006

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.