• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.211-215
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• 2008

This paper deals with the transient ground impedance of small-sized needle-rod installed in a test field, Impulse voltage generator was used to inject lightning impulse on a ground electrode and modified fall-of potential method was proposed to measure the high ground potential rise. Transient ground impedance was analysed with impedance curve and I-V curve as respects the resistivity of soil. Soil ionization near the ground electrode is activated in high resistivity soil and have an effect on the reduction of transient ground impedance significantly.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.95-99
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• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection systems is presented. The measurement and analysis of ground impedance are based on a computer aided technique. The magnitude and phase of ground impedance were measured and analyzed by the modified fall-of-potential method and the proposed computer program algerian using the waveforms of the test current and potential rise. The theoretical analysis of ground impedance were performed with the equivalent circuit models, and the theoretical results were compared with the measured data.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.192-200
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• 2011

This paper proposes a new modeling method for estimating the impedance of an on-chip power/ground meshed plane. Frequency dependent R, L, and C parameters are extracted based on the proposed method so that the model can be applied from DC to high frequencies. The meshed plane model is composed of two parts: coplanar multi strip (CMS) and conductor-backed CMS. The conformal mapping technique and the scaled conductivity concept are used for accurate modeling of the CMS. The developed microstrip approach is applied to model the conductor-backed CMS. The proposed modeling method has been successfully verified by comparing the impedance of RLC circuit based on extracted parameters and the simulated impedance using a 3D-field solver.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.470-477
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• 2002

Possibility of passive piezoelectric damping based on a new shunting parameter estimation method is studied using finite element analysis. The adopted tuning method is based electrical impedance that is found at piezoelectric device and the optimal criterion for maximizing dissipated energy at the shunt circuit. Full three dimensional finite element model is used for piezoelectric devices with cantilever plate structure and shunt electronic circuit is taken into account in the model. Electrical impedance is calculated at the piezoelectric device, which represents the structural behavior in terms of electrical field, and equivalent electrical circuit parameters for the first mode are extracted using PRAP (Piezoelectric Resonance Analysis Program). After the shunt circuit is connected to the equivalent circuit for the first mode, the shunt parameters are optimally decided based on the maximizing dissipated energy criterion. Since this tuning method is based on electrical impedance calculated at piezoelectric device, multi-mode passive piezoelectric damping can be implemented for arbitrary shaped structures.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1637-1640
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• 2005

This paper presents a technique for electromagnetic field analysis on surge response due to Mid-span back-flashovers effects in lightning protection system of 500 kV EHV single circuit transmission tower by the neural networks method. These analyses are based on modeling lightning return stroke as well as on coupling the electromagnetic fields of the stroke channel to the line. The ground conductivity influences both the electric field as well as the coupling mechanism and hence the magnitude and wave shape of the induced voltage. The technique can be used to analyzed the corona voltage effect, the effective of stroke to the span tower, the surge impedance of transmission lines. The maximum voltage from flashovers effects in the lines. The model is compatible with general electromagnetic transients programs such as the ATP-EMTP. The simulation results show that this study analyses for time-domain with those produced by a cascade multi-section model, the surge impedance of a full-sized tower hit directly by a lightning stroke is discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1087-1094
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• 2014

An numerical technique of impedance boundary condition to improve an efficiency in the process of moment method with CFIE(Combined Field Integral Equation), which is widely used to analyze the scattering property of dielectric scatterers, and results of its cross-validations are presented in this study. Application of the impedance boundary allows to represent the equivalent surface currents of dielectric scatterer depicted by both kinds of electric/magnetic surface currents(Js, Ms) to the single surface current by Js or Ms only. Accuracy of this technique is validated by the existing CFIE and theoretical values such as Mie-series solution and small perturbation scattering model. The computational difference of less than 1 dB was verified within an imaginary part of dielectric constant more than 12, as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.523-532
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• 1994

A knowledge of the accurate characteristic impedance of a GTEM cell is very useful to design it. This paper discusses the characteristic impedance of a GTEM cell applicable to both susceptibility and emission measurements, considering opening angle of it. The over-RGM for analysis is described : this numerical method is operated with respect to the spherical coordinate system. Some results are compared with others and the validity of this analysis is estabished. The characteristic impedances of a GTEM cell with the variation of geometrical constructions on cross section are presented ; the effect of the opening angle on the characteristic impedance is show. Finally, the electirc field uniformities on a cross section of a GTEM cell are considered for various opening angles.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.3
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• pp.206-209
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• 2006

This paper presents an analytical noise model for the drain thermal noise, the induced gate noise, and their correlation coefficient in deep-submicron MOSFETs, which is valid in both linear region and saturation region. The impedance field method was used to calculate the external drain thermal noise current. The effect of channel length modulation was included in the analytical equation. The noise behavior of MOSFETs with decreasing channel length was successfully predicted from our model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.668-674
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• 2004

The possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials is discussed. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work,$^{(1.2)}$ the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. Changing boundary condition Is related to not only enclosure’s geometrical shape but also acoustical treatment on walls for example, attaching of impedance patches (ex: absorptive material). In many practical situations, we often meet situation to change acoustical treatment on walls. The possibility of total acoustic potential energy(globa1 noise) reduction by acoustic source power control is examined in an acoustically small cavity Using acoustic energy balance equation, the relation between global noise control performance and absorptive material’s arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent’s distribution and impedance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.11
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• pp.28-33
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• 2002

In this paper, the impedance-tuned monopole microstrip antenna designed for PCS is analyzed using finite difference time domain(FDTD) method. The perfectly matched layer(PML) absorbing material condition proposed by Berenger is used for the truncation of finite difference time domain lattice. A Gaussian pulse is selected as an excitation signal and a resistive voltage source model is used to reduce the error caused by the reflection waves. The FDTD method is inherently a near field technique. Therefore, the near field to far field transformation is need to compute far field antenna parameters such as radiation patterns and gain. The near field to far field transformation can be done both in the time domain and the frequency domain. We use the frequency domain transformation to compute the far field radiation patterns at single frequency. All the numerical results obtained by the FDTD method are compared with simulation results using the HFSS software. Good agreements are obtained in all cases.