• Journal of the Korean Mathematical Society
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• v.43 no.1
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• pp.199-213
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• 2006

We compute the holomorphic derivative of the harmonic measure associated to a $C^\infty$bounded domain in the plane and show that the exact Bergman kernel function associated to a $C^\infty$ bounded domain in the plane relates the derivatives of the Ahlfors map and the Szego kernel in an explicit way. We find several formulas for the exact Bergman kernel and the Szego kernel and the harmonic measure. Finally we survey some other properties of the holomorphic derivative of the harmonic measure.

• Journal of applied mathematics & informatics
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• v.30 no.5_6
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• pp.865-869
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• 2012

In [2], D. Gaier has given an estimates of harmonic measure. In this paper, we generalize for the K-quasiconformal mapping the corresponding result.

• Bulletin of the Korean Mathematical Society
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• v.60 no.3
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• pp.623-636
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• 2023

In this paper, we prove some vanishing theorems under the assumptions of weighted BiRic curvature or m-Bakry-Émery-Ricci curvature bounded from below.

• Bulletin of the Korean Mathematical Society
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• v.54 no.4
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• pp.1229-1240
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• 2017

This paper presents a systematic study of the abstract harmonic analysis over spaces of complex measures on homogeneous spaces of compact groups. Let G be a compact group and H be a closed subgroup of G. Then we study abstract harmonic analysis of complex measures over the left coset space G/H.

• The Pure and Applied Mathematics
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• v.5 no.2
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• pp.101-108
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• 1998

For a smoothly bounded n-connected domain $\Omega$ in C, we get a formula representing the relation between the Szego" kernel associated with $\Omega$ and holomorphic mappings obtained from harmonic measure functions. By using it, we show that the coefficient of the above holomorphic map is zero in doubly connected domains.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.121-127
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• 2004

Electric ballast is widely used to turn on the fluorescent. Electric ballast measure occurrence of harmonic through the actual measurement and it is simulated by modeling equivalent circuit for harmonic analysis. The purpose of this paper is to give an equivalent circuit modeling methodology for the harmonic currents generated by single-phase personal computer loads to evaluate a commercially available series resonant filter for the harmonic currents compensation based on the IEC std 61000-3-2 and IEEE 519 standards for limiting harmonic distortion.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.399-402
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• 1996

The electrodynamic loudspeakers should have a wide dynamic range to reproduce various sound levels. When the input signal is small, the radiated sound from the loudspeaker is not so much distorted. However, for large input signal with low frequency component the radiated sound is significantly distorted due to the nonlinearities of the loudspeaker. The suspension, damping, and magnetic flux of loudspeaker are the main sources of the nonlinearity. Such electromechanical parameters related to harmonic distortion have been represented by a polynomial model for diaphragm displacement, while each of the polynomial coefficient is evaluated by using the principle of harmonic balance experimentally. Based on the polynomial model, we designed a compensator for nonlinear harmonic distortion of direct radiator loudspeaker. Than observer is used to estimate the displacement of the loudspeaker diaphragm, which is rather difficult to measure directly in the conventional setting. The usefulness of the designed compensator is demonstrated by numerical simulations. Simulation results show about 30db decrease at the second and third higher harmonic distortions. We carry out an experiment on speaker to verify designed controller and nonlinear observer.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.259-261
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• 2002

Recently, according to the spread of semiconductor applied technology like motor speed control contrivance, power conversion installation and so on, harmonic ingredients occurred in switching operation flow into a distribution system and increase voltage distortion of distribution system and bring on obstacles like damage, lowering of capability, false operation and so on of various electrical installation. So, in order to consider a countermeasure to limit occurrence quantity of harmonic source, harmonic interception and others, precision measurement and analysis on voltage, current, power, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion and so forth are needed. In this paper monitoring system to measure and analyze power quality connected with power harmonics was developed and it's performance is verified by measuring and analyzing three-phase voltage and current of R, S, T in the three-phase and four-wire system using the developed measurement system.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.162-166
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• 2008

This paper presents the design and implementation of a 5kW programmable three-phase harmonic generator, which is capable of generating sinusoidal output voltages with adjustable output amplitude and frequency over a wide range as well as arbitrary waveforms. The considered harmonic generator is a linear power amplifier type. This system consists mainly of a power converter to generate and amplify waveform signals, a controller to control the desired output signal and measure the output parameters including voltage and current, and a control program to set the desired output and display the output values. The prototype programmable three-phase harmonic generator has been constructed and tested. Test results show that the developed programmable three-phase harmonic generator performs well.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.378-380
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• 2003

This paper presents the optimal point for measuring harmonic levels in distribution systems. Harmonic should be measure PCC (Point of Common Coupling), where is extended over distribution systems, but some PCCs are limited for economical and technical reason : for this reason, the harmonic measurement for a real distribution system and computer simulation are performed to find the optimal PCC in this paper.