• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.473-480
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• 2020

In this paper, we proposed a high frequency equivalent circuit considering parasitic impedance components for differential noise analysis on the input stage during DC-DC buck converter switching operation. Based on the proposed equivalent circuit model, we presented a method to measure parasitic impedance parameters included in DC bus plate, IGBT, and PCB track using the gain phase method of a network analyzer. In order to verify the validity of this model, a DC-DC prototype consisting of a buck converter, a signal analyzer, and a LISN device, and then resonance frequency was measured in the frequency range between 150 kHz and 30 MHz. The validity of the parasitic impedance measurement method and the proposed equivalent model is verified by deriving that the measured resonance frequency and the resonance frequency of the proposed high frequency equivalent model are the same.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1099-1105
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• 2006

In this paper, the equivalent circuit model of a Rosen-type multilayer piezoelectric transformer(MPT) has been proposed based on the Mason's equivalent circuit model and the principle of single layer piezoelectric plate. From the piezoelectric direct and converse effects, the symbolic expressions between the electric inputs and outputs of the MPT have been derived from the equivalent circuit model. A simplified equivalent circuit model of the MPT whose driving part has a single input form has been proposed. The symbolic expressions of the driving part have been derived from the simplified equivalent circuit model and the model was compared with the multi-input equivalent circuit model through the simulation. In the comparisons between the simulation results and the experimental data, output voltage is 630 Vp-p in case of 11-layered MPT and 670 Vp-p for 13-layered MPT over the experiment range. As the load resistance increases, output voltage increases and saturates over $300k{\Omega}$ and the resonant frequency changes from 102 kHz to 103 kHz. The simulation and the experimental results agree well over different load resistances and frequencies.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.465-470
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• 2008

Sound transmission characteristics are investigated on the honeycomb panels used for railway vehicles. Equivalent orthotropic plate model and equivalent mass law are applied to predict the sound transmission loss (STL) of the honeycomb panels. The predicted values of the STL are compared with the measured values. The reliability and the limitation of the prediction models are investigated. Coincidence effect and local resonance effect on STL are considered. The result of the study shows that the equivalent orthotropic plate model can be used as a good prediction model, if the local resonance frequency is properly applied. finally, ways to improve the severe STL drop by local resonance are proposed and the effect on the sound insulation performance is analysed.

• Composites Research
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• v.33 no.6
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• pp.377-382
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• 2020

The free vibration characteristics of corrugated laminated composite plates with axial stiffeners is investigated using the Rayleigh-Ritz method. The plate is stiffened by beams with open cross-section area. The equivalent homogenization model is used for the corrugated laminated composite plates. This homogenization model is treated a corrugated plate as an orthotropic plate that has different material properties in two perpendicular directions. The motion of equivalent plate is represented on the basis of the first order shear deformation theory (FSDT) to account for the effect of rotary inertia and transverse shear deformation. Stiffeners are considered as discrete elements to predict the local vibration mode to be generated by the presence of stiffeners. To validate the proposed analytical approach, natural frequencies and vibration mode shapes from the analytical method are compared with those from the FEA by ANSYS.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.408-413
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• 2004

High speed planning boats also have been required more and more the rational strength analysis and evaluation for the optimal structural design in respect of the structural lightness according to the high speed trend. Even though the suggestion of the simple type equation for the equivalent dynamic pressure is reasonable to design the scantling of ship structure conveniently, many research activities for more reasonable improvement of the simple design pressure, have been continued to suggest the more accurate equivalent static description of tire structural response such as the deflection and stress of hull structure. In this research, we focus on the aluminum bottom stiffened plate structure in which structural scantling is mainly depend on the local loads such as dynamic or impact pressure without other load effects and structural response for the simple dynamic equivalent pressure was investigated through the structural analysis. In order to investigate the structural response of the bottom stiffened plate structure subjected to the dynamic equivalent design pressure, linear and nonlinear structural analysis of the bottom stiffened plate structure of 4.3 ton aluminum planning boat was performed based on the equivalent static applied loads which were derived from the KR regulation and representative one among various dynamic equivalent pressure equations. From above analysis results, we found that the response such as deflection and stress of plate member was similar with the response results of one plate member model with fixed boundary, which was published previous paper and in case of KR design loading, all response of stiffened plate structure were within elastic limit. Through the nonlinear analysis, nearly elastic behavior including the slight geometrical nonlinear response was dominant but plastic local zone was appeared at $85\%$ limit load. Therefore, we can say that through tire linear and nonlinear analysis, this stiffened plate member has no structural strength problem based on the yield criteria in case within $60\%$ limit load except the other strength point of view such as the fatigue and buckling problem.

• Nuclear Engineering and Technology
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• v.47 no.4
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• pp.500-511
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• 2015

In this study, the natural frequencies of the perforated square plate with a square penetration pattern are obtained as a function of ligament efficiency using the commercial finite-element analysis code ANSYS. In addition, they are used to extract the effective modulus of elasticity under an assumption of a constant Poisson's ratio. The effective modulus of elasticity of the fully perforated square plate is applied to the modal analysis of a partially perforated square plate using a homogeneous finite-element analysis model. The natural frequencies and the corresponding mode shapes of the homogeneous model are compared with the results of the detailed finite-element analysis model of the partially perforated square plate to check the validity of the effective modulus of elasticity. In addition, the theoretical method to calculate the natural frequencies of a partially perforated square plate with fixed edges is suggested according to the Rayleigh-Ritz method.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.17-22
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• 2005

This paper presents a improvement equivalent circuit model for Miniaturized LTCC bandpass filter with two transmission zeros using feed-back capacitor. The bandpass filter equivalent circuit is evaluated by parallel network analysis. Besides, the filter is modeled by proposed passive element modeling algorithm in previous work. Compared to the equivalent circuit of established paper that is configured by excepted capacitance between ground plate and signal plate, this model can include that. The result, the LTCC bandpass filter reduce layers and the size is more smaller.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.404-411
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• 2010

Authors conducted a deduction and characteristic calculation of the some parameters using a magnetic equivalent circuit method to verify a basic design result of a rotary-typed small-scaled linear induction motor for a railway transit. In a LIM, it is possible to express the parameters of the magnetic equivalent circuit into a function of the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. It means that the LIM properties can be changed considerably by the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. So, authors analyzed a tendency of changes of the magnetic equivalent circuit parameters and the LIM characteristics by changing of the airgap, the thickness of the secondary aluminium plate and the overhang length and shape of a rotary-typed small-scaled LIM, and accomplished a basic research to develop a real-scaled LIM for a railway transit.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.5
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• pp.805-816
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• 2015

In the present study, external restraints imposed normal to the plate during the cooling stage were determined to be effective for reduction of the angular distortion of butt-welded or fillet-welded plate. A welding analysis model under external force during the cooling stage was idealized as a prismatic member subjected to pure bending. The external restraint was represented by vertical force on both sides of the work piece and bending stress forms in the transverse direction. The additional bending stress distribution across the plate thickness was reflected in the improved inherent strain model, and a set of inherent strain charts with different levels of bending stress were newly calculated. From an elastic linear FE analysis using the inherent strain values taken from the chart and comparing them with those from a 3D thermal elasto-plastic FE analysis, welding deformation can be calculated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.402-407
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• 1997

For cylindrical shells, the closed-form solutions are limited only to the cases with special boundary and/or loading conditions. Though the finite element method is certainly a powerful solution approach for the general structural dynamics problems, it is known to provide reliable solutions only in the low frequency region due to the inherent high sensitivities of structural and numerical modeling errors. Instead, the spectral element method has been proved to provide extremely accurate dynamic responses even in the high frequency region. Since the wave characteristics of a cylindrical shell becomes identical to that of a flat plate as the frequency increases, an equivalent plate model (EPM) representing the high-frequency dynamic characteristics of a cylindrical shell is introduced herein. The EPM-based spectral element analysis solutions are compared with the known analytical solutions for the corresponding cylindrical shell to confirm the validity of the present modeling approach.