• Title/Summary/Keyword: 시간영역 유한차분

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Numerical Simulation of Two-Dimensional Shipping Water by Using a Simplified Model (단순화 모델에 의한 2차원 갑판침입수의 수치 시뮬레이션)

  • Kim, Yong J.;Kim, In C.
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.2
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    • pp.1-12
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    • 1996
  • Hydrodynamic characteristics of shipping water on deck are investigated by using a simplified two-dimensional model. Formulation of the shipping water on deck leads to a nonlinear hyperbolic system of equations based on the shallow-water wave theory. Time-domain solution of these equations are obtained numerically using a finite difference method which adopts predictor-corrector method for time-marching and 2nd upwind differencing method for convection term calculation. To confirm the validity of the present numerical method, we calculated some shallow-water wave problems accompanying a bore and compared the obtained results with the analytic solutions. We found good agreements between them. Though the calculation results of shipping water on deck, we show that the shipping water flows into the deck as a rarefying wave arid grows into a bore after colliding with a deck structure. Also we examined the effects of acceleration and slope of deck and found that they have significant influences on the flow of shipping water.

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Dual-Band Microstrip Antenna for ISM Band using Aperture Coupled Cross Patch (개구 결합된 십자형 패치를 이용한 ISM 대역용 이중대역 마이크로스트립 안테나)

  • 박기동;정문숙;임영석
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.5
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    • pp.479-488
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    • 2003
  • Dual-band microstrip antenna is designed for industrial-scientific-medical(ISM) band of 2.4 GHz and 5.8 GHz using finite-difference time-domain method(FDTD). Cross patch 130 by aperture in the ground plane of microstrip line is proposed as radiation element of antenna which is 2 rectangular patch is overlapped. To design antenna, change of input impedance is examined by length change of aperture and stub. And center frequency and - 10 dB bandwidth are investigated by change of length and width in radiation element. Measured result about reflection loss confirm that agree well with simulation results of FDTD and IE3D. And 3 dB beam width, front to back ratio and maximum gain is presented by measuring radiation pattern of antenna in frequency 2.43 GHz and 5.79 GHz.

Internal Resistive Source Modeling Technique for the Efficient Analysis of Planar Microwave Circuits Using FDTD (FDTD를 이용한 평판 구조 마이크로파 회로의 효율적인 해석을 위한 내부 저항 소스 모델링 방법)

  • 지정근;최재훈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.2
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    • pp.227-236
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    • 1999
  • The finite difference time domain method (FDTD) is widely applied to the analysis of various microwave circuits. However, previous source modeling techniques have a lot of constraints and difficulties to apply for general geometries. Therefore, the internal resistive source modeling technique is suggested for efficiently analyzing various types of microwave circuit in this paper. Its efficiency is proved by comparing the computation time with that of hard source modeling. Accuracy is also verified by comparing the scattering parameters with those of previous source modeling methods and measurements for several microwave circuits.

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A Study of Wideband Method for the Millimeter-wave Planar Antenna (밀리미터파대 평면형 안테나의 광대역화 방안)

  • 이형수;설동범;이윤경;백락준;윤현보
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.2
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    • pp.206-216
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    • 2000
  • In this paper, the linear tapered slot(LTS) antenna and linear constant tapered slot(LCTS) antenna are optimized for millimeter-wave antenna by the finite difference time domain(FDTD) method and then fabricated and measured. The microstrip-to-slot transition is proposed with the widen $\lambda$/4 open stub as feeder for wide bandwidth of 16.5GHz($VSWR\leq2$). The results of the calculation and measurement, the bandwidth of LTS antanna is 8.3GHz(26.47%) and 7.1792GHz(22.4%) respectively. Also, the bandwidth of LCTS antenna is 8.1GHz(26.47%) and 6.3243GHz(20.43%) respectively.

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FDTD Modeling of the Korean Human Head using MRI Images (MRI 영상을 이용한 한국인 인체 두부의 FDTD 모델링)

  • 이재용;명노훈;최명선;오학태;홍수원;김기회
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.4
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    • pp.582-591
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    • 2000
  • In this paper, the Finite-Difference Time-Domain(FDTD) modeling method of the Korean human head is introduced to calculate electromagnetic energy absorption for the human head by mobile phones. After MRI scanning data is obtained, 2 dimensional(2D) segmentation is done from the 2D MRI image data by the semi-automatic method. Then, 3D dense segmentation data with $1mm\times1mm\times1mm$ is constructed from the 2D segmentation data. Using the 3D segmentation data, coarse FDTD models of human head that is tilted arbitrarily to model the condition of tilted usage of mobile phone.

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EMI Analysis on High Speed Digital Circuite (고속 디지털 회로 PCB 상의 EMI 해석)

  • Kim, Tae-Hong;Lee, Hyeon-Jin;Lim, Yeong-Seog
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.12
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    • pp.159-164
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    • 2005
  • Recently, it has demanded high-speed digital circuits as information increase. Therefore, electromagnetic characteristics of compact microwave circuit occurred importantly. And, the effect of the imperfect ground plane on the signal integrity and influence of coupling between two parallel lines for high-speed digital transmission line on the printed circuit board is investigated by FDTD simulations in 3-D electromagnetic analysis method. The results of FDTD simulation are compared with the ADS simulation in commercial software, analyzed lumped element of modeling and electromagnetic wave's radiation of slot as frequency. As a consequence, when the slot in the ground plane is under microstrip line, it has much effect on propagation of wave.

A Design of Broadband Biconical Antenna with Tapered Section (테이퍼 구조를 갖는 광대역 바이코니컬 안테나의 설계)

  • Kim, Jun-Kyu;Lee, In-Jae;Yoon, Hyun-Bo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.11 s.114
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    • pp.1096-1104
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    • 2006
  • In this paper, the broadband antenna for the combined base station of Cellular/PCS/IMT-2000/Wibro and S-DMB services is designed and the proposed antenna allows having sufficient coverage for each service band. In order to get the broadband impedance matching, the tapered sections are applied on the both terminus of hi-conical respectively. The design parameter is calculated and simulated by using FDTD method. As a result, the measured bandwidth of the proposed antenna is $0.79GHz{\sim}2.93GHz$ and the gain is distributed from 5.5 dBi up to 8.19 dBi.

EMC design for TDX-1B subscriber Board (전전자 교환기 가입자회로의 EMI 대책 설계연구)

  • 윤현보;임계재
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.6 no.1
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    • pp.48-65
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    • 1995
  • This paper deals with the analysis of the unintentional radiation from the TDX-1B subscriber Board. According to the demand of digital systems and developement of high speed switching devices, electro- magnetic noise intensity and it's bandwidth occupancy in spectrum are increasing and so there is a serious possibility causing the various EMI phenomena. More accurate radiation model was established by using the Finite Difference Time Domain (FDTD) analysis, and the EMI probabilistic analysis of the digital switching system was performed. For validating the proposed model and its calculated results, on-promises test was performed and compared with the calculated results. These results may be applicable to be used for EMI model in large digital system, and prediction of EMI effect from a large digital system, and the EMI control design when designing digital system to meet inter- national EMI regulation.

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Two Dimensional Explicit ID(Isotropic-Dispersion)-FDTD Scheme for Lossy Media (손실 매질에 대한 2차원 등방 시간 영역 유한 차분법)

  • Koh, Il-Suek;Kim, Hyun;Yook, Jong-Gwan
    • 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.

Characteristic Analysis of Monopole Antenna and PIFA Mounted on Handheld Telephone (휴대용 이동통신 전화기에 탑재된 모노폴 안테나와 PIFA 안테나의 특성 해석)

  • Park, Ju-Derk;Kim, Nam
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.2
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    • pp.31-40
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    • 1999
  • Characteristics of monopole antenna and planar conductor structure mounted on handheld telephone are anlayzed by using FDTD method. Feeding of monopole antenna is implemented with lumped elements and plastic case is coated on the surface of conductor box. Otherwise, resonant frequency of handheld telephone mounting monopole antenna with no plastic case is 877MHz, when plastic case (${\varepsilon}_r=2$) is coated, the resonant frequency is down to 82MHz and the bandwidth is broadened about 1.5 times. Planar structure of handheld telephone mounted on the body makes to change far-field gain radiation patterns. In this case, radiation patterns are somewhat asymmetrical. Handheld telephone using PIFA(Planar Inverted F Antenna), instead of monopole antenna, is resonated at frequency 1.52GHz that is available onPCS. In the radiation pattern of this structure, azimuth that electric field intensity is presented below 20dB is 14$^{\circ}$.

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