• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.5
• /
• pp.648-658
• /
• 1998

In this paper, the effect of the gap in the ground plane on the electromagnetic interference (EMI) is analyzed quantitatively. Because of a lot of advantages compared to other numerical techniques, the FDTD (finite difference time domain) is applied to the EMI effect modeling. The analyzed model is the simplified PCB (printed circuit board) which has a microstrip and ground plane. The inductance induced by the gap is modeled and calculated by gridding the whole PCB based on the FDTD algorithm. When external cables are attached to the PCB, the common-mode current is induced along the attached cable and the resulting electric field strength is calculated and presented along with the FCC and CISPR EMI limits. The results show that the radiated field strength highly depends on the size of the ground plane gap. The numerical simulation results can be used as a reference in the practical PCB design with the ground plane gap.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.03a
• /
• pp.365-372
• /
• 1999

The plane deformation and spatial seepage(PDSS) analysis was developed to consider 3D flow of excess pore water as well as plane deformation of ground. Here is newly developed an equivalent model for PDSS analysis, which was the purpose to reduce number of finite elements and to take the effects of smear and well resistance into consideration. As the result of PDSS analysis with applying the new model, it is showed that the settlement-tin e relationship by PDSS agrees well with those of Plane strain(PS) and axisymmetric analyses, irrespective of existence of untreated layer. And the excess pore pressure distribution by PDSS is relatively agreed with that of axisymmetric analysis, not with that of PS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.217-227
• /
• 2000

A rectangular ceramic dielectric antenna, placed on the top of a ground plane and fed by coaxial probe, is analyzed by using the finite element method. To verify the proposed code, a rectangular ceramic dielectric antenna was fabricated and the characteristics of antenna were measured. The numerical data obtained is in good agreements with experimental result. Thus we checked the validity of our FEM code, and it can be possible to extend the analysis of the arbitrary 3-D antenna on a ground plane fed by coaxial probe.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.12
• /
• pp.2468-2478
• /
• 1994

A hybrid finite element method is presented for a characterization of scattering an radiation properties of microstrip patch and arrays residing in a cavity recessed in a ground plane. The technique combines the finite element and boundary integral methods to formulate a system for the solution of fields at the aperture and the scattering field and radar cross sections at free space. By virture of the finite element method, the proposed technique is applicable to patch antennas and arrays residing on or embeded in a layered dielectric loss/lossless substrate and is also capable of treating various feed configuration. Several numerical results are presented demonstrating the validity, efficiency and capability of the technique.

• Journal of electromagnetic engineering and science
• /
• v.18 no.3
• /
• pp.175-181
• /
• 2018

The array patterns of a patch array antenna were calculated using an active element pattern (AEP) method that considers ground edge effects. The classical equivalent radiation model of the patch antenna, which is characterized by two radiating slots, was adopted, and the AEPs that include mutual coupling were precisely calculated using full-wave simulated S-parameters. To improve the accuracy of the calculation, the edge diffraction of a ground plane was incorporated into AEP using the uniform geometrical theory of diffraction. The array patterns were then calculated on the basis of the computed AEPs. The array patterns obtained through the conventional AEP approach and the AEP method that takes ground edge effects into account were compared with the findings derived through full-wave simulations conducted using a High Frequency Structure Simulator (HFSS) and FEKO software. Results showed that the array patterns calculated using the proposed AEP method are more accurate than those derived using the conventional AEP technique, especially under a small number of array elements or under increased steering angles.

• Structural Engineering and Mechanics
• /
• v.58 no.2
• /
• pp.243-257
• /
• 2016

The aim of this study is to investigate the seismic resistance of dry stone arches under in-plane seismic loading. For that purpose, several numerical analyses were performed using the combined finite-discrete element method (FDEM). Twelve types of arches with different ratios of a rise at the mid-span to the span, different thicknesses of stone blocks and different numbers of stone blocks in the arch were subjected to an incremental dynamic analysis based on excitation from three real horizontal and vertical ground motions. The minimum value of the failure peak ground acceleration that caused the collapse of the arch was adopted as a measure of the seismic resistance. In this study, the collapse mechanisms of each type of stone arch, as well as the influence of the geometry of stone blocks and stone arches on the seismic resistance of structures were observed. The conclusions obtained on the basis of the performed numerical analyses can be used as guidelines for the design of dry stone arches.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.4
• /
• pp.473-478
• /
• 2011

The extent of a rectangular conducting plane for measuring electromagnetic interference is discussed. Mutual coupling between the transmit and receive antennas is negligible, the effects of the ground plane on the normalized site attenuation(NSA) are considered by applying GTD(Geometric theory of diffraction). The calculation was done for the case that measuring distance(d) was 3 m for both horizontal and vertical polarizations. As the result, the size of the rectangular ground plane almost never affects upon NSA for horizontal polarization, but for vertical case, when both width and length of the rectangular plane are several times as long as distance, the effects of the edges are reduced under 1 dB.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.1
• /
• pp.27-35
• /
• 2012

In this study, the ground motion was synthesized using the finite fault model by the stochastic green function method, and the difference in the ground motions was evaluated by using various values of the source parameters. An earthquake with a moment magnitude of 6.5 was assumed for the example fault model. The distribution of the slip in the fault plane was calculated using the statistical data of the asperity area. The source parameters considered in this study were the location of the hypocenter in the fault plane and the ratio of the rupture to the shear wave velocity, the rise time, the corner frequency of the source spectrum, and a high frequency filter. The values of the parameters related to the stochastic element source model were adjusted for different tectonic regions, and the others were selected for several possible cases. The response spectra were constructed from the synthesized ground motion time history and compared with the different parameter values. The frequency range affected by each parameter and the differences of the spectral accelerations were evaluated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.7
• /
• pp.1065-1073
• /
• 1999

This paper analyzed the ground bounce caused by the power plane resonance in the multilayered printed circuit board(PCB) using the Haar-wavelet-based Multiresolution Time-Domain (MRTD). In conventional Finite-Difference Time-Domain(FDTD), the highly fine vertical cell is needed to represent the distance between $V_{cc}$ plane and ground plane since the two planes are very close. Therefore the time step $\Deltat$ must be very small to satisfy the stability condition. As a result, a large number of iterations are needed to obtain the response in wanted time. For this problem, this paper showed that the computation time can be reduced by application of the MRTD method. The results obtained by the MRTD agree very well with those by FDTD method and analytic solutions. In conclusion, this paper proved the efficiency and accuracy of MRTD method for analyzing the EMI/EMC problems in PCB.

• Structural Engineering and Mechanics
• /
• v.23 no.3
• /
• pp.233-247
• /
• 2006

Most codes of practice state that for large in-plane structures it is necessary to account for the spatial variability of earthquake ground motion. There are essentially three effects that contribute for this variation: (i) wave passage effect, due to finite propagation velocity; (ii) incoherence effect, due to differences in superposition of waves; and (iii) the local site amplification due to spatial variation in geological conditions. This paper discusses the procedures to be undertaken in the time domain analysis of a cable-stayed bridge under spatial variability of earthquake ground motion. The artificial synthesis of correlated displacements series that simulate the earthquake load is discussed first. Next, it is described the 3D model of the International Guadiana Bridge used for running tests with seismic analysis. A comparison of the effects produced by seismic waves with different apparent propagation velocities and different geological conditions is undertaken. The results in this study show that the differences between the analysis with and without spatial variability of earthquake ground motion can be important for some displacements and internal forces, especially those influenced by symmetric modes.