• Journal of Power Electronics
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• v.16 no.6
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• pp.2338-2349
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• 2016

This paper presents an impedance-matching-based control scheme for the harmonic resonance damping of multiple grid-connected-converters (GCCs) with LCL filters. As indicated in this paper, harmonic resonance occurs if a GCC possesses an output impedance that is not matched with the rest of the network in some specific frequency bands. It is also revealed that the resonance frequency is associated with the number of GCCs, the grid impedance and even the capacitive loads. By controlling the grid-side current instead of the converter-side current, the critical LCL filter is restricted as an internal component. Thus, the closed-loop output impedance of the GCC within the filter can be configured. The proposed scheme actively regulates the output impedance of the GCC to match the impedance of the external network, based on the detected resonance frequency. As a result, the resonance risk of multiple GCCs can be avoided, which is beneficial for the plug-and-play property of the GCCs in microgrids. Simulation and experimental results validate the effectiveness of the proposed method.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.203-206
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• 2000

In this paper, we discuss an efficient steady-state analysis of reactance oscillators having multiple oscillations. Our oscillator is consisted of the Cauer or Foster reactance sub-circuit and a negative resistor such as tunnel diode. The reactance circuit has many resonance and antiresonance points on the frequency response curve. Such a circuit having the specified resonance and anti-resonance points can be easily synthesized with the fundamental circuit theory. In this case, the multiple oscillations may occur near at the anti-resonance points. We have developed a user friendly simulator for getting the exact steady state responses using the SPICE.

• Investigative Magnetic Resonance Imaging
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• v.22 no.3
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• pp.187-193
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• 2018

Sweet's syndrome also known as acute neutrophilic dermatosis is a multisystem inflammatory disorder characterized by fever, malaise, leukocytosis, and skin lesions. Sweet's syndrome affects multiple organs though only rarely does it affect the central nervous system (CNS) when it does it is called Neuro-Sweet disease (NSD). We report on a case study of a biopsy-proven NSD in a 50 year old man. Serial magnetic resonance imaging (MRI) showed repeated CNS involvement of Sweet's syndrome after a respiratory tract infection preceded it. On the MRI, T2 hyperintense lesions occurred at multiple sites and disappeared after steroid therapy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.1-5
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• 2009

In this paper, a novel wideband crossed planar monopole antenna with the multiple resonance characteristics is proposed. The proposed monopole antenna can be designed by a wideband crossed planar monopole antenna with L-shaped slits. In order to generate multiple resonance characteristics on the proposed monopole antenna, the length of L-shaped slit and the number of L-shaped slits are determined at an interesting frequency. The proposed antenna having an omnidirectional radiation pattern and a high gain over the multiple resonance frequency bands, respectively, is suitable for a mobile antenna.

• Earthquakes and Structures
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• v.22 no.4
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• pp.373-386
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• 2022

The development of performance-based design methodologies requires a reasonable definition of a displacement-response spectrum. Although ground motions are known to be significantly affected by the resonant-like amplification behavior caused by multiple wave reflections within the surface soil, such a soil-resonance effect is seldom explicitly considered in current-displacement spectral models. In this study, an analytical approach is developed for the construction of displacement-response spectra by considering the soil-resonance effect. For this purpose, a simple and rational equation is proposed for the response spectral ratio at the site fundamental period (SRTg) to represent the soil-resonance effect based on wave multiple reflection theory. In addition, a bilinear model is adopted to construct the soil displacement-response spectra. The proposed model is verified by comparing its results with those obtained from actual observations and SHAKE analyses. The results show that the proposed model can lead to very good estimations of SRTg for harmonic incident seismic waves and lead to reasonable estimations of SRTg and soil displacement-response spectra for earthquakes with a relatively large magnitude, which are generally considered for seismic design, particularly in high-seismicity regions.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2001.02a
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• pp.24-24
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• 2001

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2000.01a
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• pp.3-4
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• 2000

• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.847-858
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• 2011

We make use of the simplified Hirota's bilinear method with computer symbolic computation to study a variety of coupled potential KdV (pKdV) equations. Each coupled equation is completely integrable and gives multiple soliton solutions and multiple singular soliton solutions. The phase shifts for all coupled pKdV equations are identical whereas the coefficients of the obtained solitons are not identical. The four coupled pKdV equations are resonance free.

• Bulletin of the Korean Mathematical Society
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• v.51 no.5
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• pp.1433-1451
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• 2014

In this paper we study the existence of multiple periodic solutions of second-order ordinary differential equations. New results of multiplicity of periodic solutions are obtained when the nonlinearity may cross multiple consecutive eigenvalues. The arguments are proceeded by a combination of variational and degree theoretic methods.

• Journal of KSNVE
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• v.7 no.1
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• pp.55-60
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• 1997

In order to examine the validity of an asymptotic solution obtained from the method of multiple scales, we investigate a third-order subharmonic resonance response of a bar constrained by a nonlinear spring to a harmonic excitation. The motion of the bar is governed by a linear partial differential equation with a nonlinear boundary condition. The nonlinear boundary value problem is solved by using the finite difference method. The numerical solution is compared with the asymptotic solution.