• Computational Structural Engineering : An International Journal
• /
• v.2 no.1
• /
• pp.33-42
• /
• 2002

A computationally efficient stiffness design method for building structures is proposed in which dynamic soil-structure interaction based on the wave-propagation theory is taken into account. A sway-rocking shear building model with appropriate ground impedances derived from the cone models due to Meek and Wolf (1994) is used as a simplified design model. Two representative models, i.e. a structure on a homogeneous half-space ground and a structure on a soil layer on rigid rock, are considered. Super-structure stiffness satisfying a desired stiffness performance condition are determined via an inverse problem formulation for a prescribed ground-surface response spectrum. It is shown through a simple yet reasonably accurate model that the ground conditions, e.g. homogeneous half-space or soil layer on rigid rock (frequency-dependence of impedance functions), ground properties (shear wave velocity), depth of surface ground, have extensive influence on the super-structure design.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.7
• /
• pp.3474-3481
• /
• 2013

In this work, a new high frequency transmission line structure combined with defected ground structure (DGS) and artificial dielectric substrate (ADS) structure is proposed. DGS patterns give add the additional inductance to transmission lines and results in the increased characteristic impedance for a given line width. To the contrary, ADS presents increased capacitance and reduced line impedance. So both play a role in reducing the length of transmission lines commonly, but in preserving the line impedance complementarily. This means that the length of transmission lines can be reduced furtherly by DGS and ADS without a critical change of line width compared to the cases when one of DGS and ADS is used only. As examples, $35{\sim}100{\Omega}$ transmission lines having DGS and ADS are designed, fabricated, measured, and compared to the simulation results. A good agreement between the simulated and measured line impedances is presented. In addition, the physical lengths of the proposed transmission lines are only 55.4~76.9% of those of the normal microstrip lines for the same electrical lengths.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.1
• /
• pp.98-104
• /
• 2010

In order to evaluate the performance of a grounding system against lightning or fault currents including high frequency components, the grounding impedance should be considered rather than the steady state ground resistance. To evaluate the ground impedance, the frequency dependence of resistivity and relative dielectric constant of the soil have to be analyzed. This paper deals with the frequency dependence of the resistivity and relative dielectric constant of three types of soil on water content. As a result, the resistivity of soil is getting lower with increasing of water content. It is nearly independent of the frequency in the range less than 1[MHz], and is decreased over the frequency range above 1[MHz]. On the other hand, the relative dielectric constant is rapidly decreased with the frequency in the range less than 1[MHz], but it is nearly independent on the frequency over the range of 1[MHz]. It was found from the experiments that the frequency-dependant resistivity and relative dielectric constant of soil should be considered when designing the grounding systems for protection from lightning or switching surges.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.10
• /
• pp.1086-1095
• /
• 2008

In this paper, we designed and fabricated the trapezoidal antenna using the CPWG structure for Wibro and WLAN communications. This antenna has broadband characteristics using the basic trapezoidal antenna, and an H-shaped parasitic patch is making an expansion of resonance bandwidth and bringing stability of impedance matching. Especially, CPWG structure is combined two kinds of the structure which of a monopole antenna and a coplanar waveguide antenna. They make up for the weak point of the CPW which is variation of impedance matching according to varying the gap or size of the feed line and the ground. The designed antenna has occurred resonances of which the band of 2.2 GHz to 4.6 GHz(70.5 %) below the return loss of -10 dB($VSWR{\leq}2$) obtained in measurement, and it has an omnidirectional radiation pattern of H-plane. In addition, the changes of impedance matching appear slightly caused by the effects of the ground plane and the feed line.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.6
• /
• pp.740-747
• /
• 2019

In this paper, an antenna applicable to WLAN and WiMAX frequency bands is designed, fabricated, and measured. The proposed antenna is designed to have two branch strip line in the patch plane and a rectangular slit in the ground plane based on microstrip feeding for triple band characteristics and added a vertical strip in the ground plane to enhance impedance bandwidth characteristics. The proposed antenna is designed on a substrate with a relative permittivity of 4.4, a thickness of 1.0 mm, and has a size of $18.0mm(W1){\times}37.3mm$ (L4+L5+L7). From the fabricated and measured results, impedance bandwidths of 480 MHz (2.32 to 2.80 GHz) for 2.4/2.5 GHz band, 810 MHz (3.22 to 4.03 GHz) for 3.5 GHz band, and 1,820 MHz (5.05 to 6.87 GHz) for 5.0 GHz band were obtained based on the impedance bandwidth. Measured 3D pattern and gains are displayed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.63-68
• /
• 2005

In this paper, Coplanar Waveguide(CPW) low-pass filter with the spurious-reduced is designed by using Defected Ground Structures(DGS). Two different LPF unit cells and DGS pattern are combined to reduce the spurious. In comparison to a conventional step impedance LPF, the size of proposed LPF as 17.2mm*6.8mm is several times smaller. The simulation and measurements confirm that spurious characteristics is presented less than -30dB($S_{21}$) to three times cut off frequency.

• Journal of electromagnetic engineering and science
• /
• v.7 no.1
• /
• pp.7-11
• /
• 2007

PCB Power-Bus (comprising power/ground planes) impedance and fields are evaluated by an efficient series expansion method that is suggested in this paper. It is used to investigate the structure's radiated emission(RE) levels and find acceptable ways of loading the power/ground planes such as decoupling capcitor(DeCap)s, balanced feeding and slits, in order to reduce the interferences. Also, the calculations and measurements of a proposed geometry are verified by vector fitting as a analysis model to check the behavior of the slit.

• Journal of electromagnetic engineering and science
• /
• v.18 no.4
• /
• pp.261-266
• /
• 2018

This paper reports on the proposed design of a low profile broadband array antenna for home repeater applications. The proposed antenna consists of $1{\times}4$ patch elements and two ground planes, one of which is slitted. By using the gap feeding method, the impedance matching of the antenna is improved by a multi-resonance phenomenon. The proposed antenna provides a wide -10 dB reflection coefficient bandwidth simultaneously covering the Global System for Mobile communications (GSM-1800), Personal Communications Service (PCS), and the Universal Mobile Telecommunication System (UMTS) bands (1.67-2.32 GHz). In order to reduce the mutual coupling between adjacent patch elements, slits are embedded in the ground plane. An isolation level of -20 dB is realized over the entire operating frequency band.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.54 no.4
• /
• pp.163-170
• /
• 2005

This paper deals with an improved fault location algorithm with compensation ground capacitance through distributed parameter for a long parallel T/L. For the purpose of fault locating algorithm non-influenced by source impedance and fault resistance, the loop method was used in the system modeling analysis. This algorithm uses a positive and negative sequence of the fault current for high accuracy of fault locating calculation. Power system model of 160km and 300km long parallel T/L was simulated using EMTP software. To evaluate of the proposed algorithm, we used the several different cases 64 sampled data per cycle. The test results show that the proposed algorithm was minimized the error factor and speed of fault location estimation.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.347-348
• /
• 2008

We investigate the characteristics of a dipole antenna on an artificial magnetic conductor (AMC) constructed of a normal material and a ground plane. We studied how the antenna performance is affected by changes in the dipole length and the distance between the dipole and the ground plane. The relation between the reflection phase of the AMC and the input resistance of the dipole for input impedance matching is also verified.