• Journal of Power Electronics
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• 제13권3호
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• pp.329-338
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• 2013

In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio ($k=C_p/C_s$), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.156-160
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• 1996

A vibrating angular rate sensor with tuning fork type resonator of microstructure (940*820 .mu. m$^{2}$) was designed and will be fabricated by polysilicon surface micromaching. The angular rate sensor is driven in a lateral direction by electrostatic force of comb drive electrodes, and vertical vibrations of the sensor, thich is detected capacitively, are produced by Coriolis forces due to an external angular rate. Mechanical Q factors and a difference between the frequencies of the two resonant modes, the driving mode and detecting mode, play a great role in increasing the sensitivity of the sensor. To be a highly sensitive sensor, it was designed to have as small frequency discrepancy of the two resonant modes as possible. Finite element method was used for the modal analysis. Several design parameters were selected and their contributions to the modal frequencies were investigated. A method was presented for tuning the detecting mode frequency by DC bias on the drive electrodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.269-272
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• 1990

This paper introduces a technique of shifting the resonant frequency and of depressing the spurious modes in the composite piezoelectric vibrator laminated in the order of piezoelectric vibrator/thin insulator/piezoelectric vibrator, whose vibrators have the the same sizes and the same properties, respectively. The composite vibrator has shown the characteristics that the fundermental resonant frequency has decreased and spurious modes have depressed with increase of the capacitance of the inserted insulator. And the frequency characteristics of the composite vibrator without insulator have been nearly the same as those of each vibrator.

• ETRI Journal
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• 제41권3호
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• pp.289-297
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• 2019

In this paper, a wideband, circularly polarized patch antenna is proposed that leverages the unidirectional resonant modes of a circular patch mounted on top of a grounded dielectric-ferrite substrate. The proposed antenna is fed via the proximity coupling method and several parasitically coupled patches are placed on a dielectric superstrate to enhance the impedance bandwidth of the antenna. The resonant modes of the structure rotate only in the clockwise or counter clockwise directions. In the frequency range where the effective permeability of the ferrite layer is negative, the resonance frequencies of these modes differ significantly, which produces a large axial ratio (AR) bandwidth. For the proposed antenna, the numerical results show the 10 dB impedance bandwidth to be around 44% and the 3 dB axial ratio bandwidth to be higher than 64%.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.167-171
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• 2003

Acoustic characteristics of baffled combustion chamber to elucidate suppressing effect of baffle on combustion instability are numerically investigated by linear acoustic analysis. A hub-blade baffle of 5 blades is selected as a candidate one and five variants of baffles with various configuration are designed. Resonant-frequency shift and damping factor are analyzed quantitatively as damping parameters. When the hub is located radially at the pressure node, the decrease of resonant frequency and increase of damping factor in 1R mode are dominant. But sub-1T mode is formed within hub, therefore, there would be a possibility of initiating 1T mode in unbaffled region, which would occur another problem. For smaller hub size, four kinds of axial baffle length is selected. As the axial baffle length increases, resonant frequency shift and increase of damping factor of transverse acoustic modes is obtained. Especially, two close acoustic modes such as 1L and 1T could be overlapped for a certain axial length, resulting in extreme increase of damping factor. The present study based on linear acoustic analysis is expected to be a useful confirming tool to predict acoustic field and design a passive control devices such as baffle and acoustic cavity.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.446-448
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• 2008

A new plasma display panel sustaining driver using single side sustaining technique with the dual resonant method is proposed. Since this circuit enables to reduce switches in energy recovery circuit with keeping voltage stress like that of prior circuit, it can be low cost circuit comparing with a conventional driver. To integrate sustain function into one side with single power source in the driver, a charge pump method is adopted to make negative sustaining voltage and achieve dual resonant energy recovery on sustaining modes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.431-434
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• 2002

In this paper, The resonant frequencies of any modes in the dielectric resonator filter is determined by numberical analysis. The theoretical analysis for the dielectric resonator filter used Ansoft HFSS. We designed the dielectric resonator filter with resonant frequency 4.5 GHz. We describe the characteristics of delivering Power to resonator in different shaped coupling loops. Tile resonant mode of T $E_{01{\delta}}$ and T $E_{01{\delta}}$ could be selected by the horizontal and the vertical coupling loop.p.

• Journal of Theoretical and Applied Mechanics
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• 제1권1호
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• pp.29-67
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• 1995

A procedure is formulated, in this paper, to compute the bifurcation modes born by the stability change of normal modes, and to compute the forced responses associated with bifurcation modes in inertially and elastically coupled nonlinear oscillators. It is assumed that a saddle-loop is formed in Poincare map at the stability chage of normal modes. In order to test the validity of procedure, it is applied to one-to-one internal resonant systems in which the solutions are guaranteed within the order of a small perturbation parameter. The procedure is also applied to the exact system in which normal modes are written in exact form and the stability of normal modes can be exactly determined. In this system the stability change of normal modes occurs several times so that various types of bifurcation modes are created. A method is described to identify a fixed point on Poincare map as one of bifurcation modes. The limitations and advantage of proposed procedure are discussed.

• 한국전자파학회논문지
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• 제10권3호
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• pp.351-358
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• 1999

본 논문에서는 유전체가 삽입된 원통형 공진기에서 공진주파수들의 모드를 구분하는 방법에 대하여 기술한다. 공진주파수들의 모드를 구분하기 위해 먼저 빈 원통형 공진기에서 계산된 공진주파수와 EM 시뮬레이터인 Microstripes의 시뮬레이션 결과 값을 비교하였다. TE 모드는 가계를 z방향으로 여기시켰을 때, TM 모드는 자계를 ∮방향으로 여기시킨 경우와 비교하여 구분할 수 있었다. 가운데 유전체가 삽입된 원통형 공진기에 이 결과를 적용해 실험결과와 비교하여 모드를 구분하였다. 이 방법이 올바른 지를 확인하기 위해 유전체의 높이를 변화시키며 모드 추적을 하였다. TE011 모드는 공진주파수의 변화가 커서 다른 공진모드와 순서가 바뀌었으나, TE111 모드와 TE211 모드는 공진주수의 변화가 적었다.

• 조명전기설비학회논문지
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• 제14권3호
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• pp.6-14
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• 2000

고효율 다중공진형 컨버터는 스위칭 손질을 다중공진 회로를 이용하여 감소시킬 수 있기 때운에 고주파에서 동작이 가능하다. 이려한 고주파 스위칭 동작은 컨버터에 높은 전력 밀도를 제공한다. 그러나 공진 스위치애 걸리는 전압 스트레스는 입력전압의 4~5배 정도여서, 높은 정격의 소자를 필요로 하기 때문에 소자의 온-저항으로 인한 전도 손실을 증가시킨다. 본 문에서는 이러한 문제점 해결하기 위해 제안했던 전압 스트레스를 줄일 수 있는 AT 포워드 MRC는 모델링 해석파 이를 이용한 등가 모드 해석을 하였다. AT 포워드 MRC는 2개의 다중 공전 스위치의 동작 순서에 따라 8개의 등가 모델링이 가능하다. 이 컨버터의 동작 원리는 입력 48[V], 출력 5[V]/50[W]의 실험세트와 PSpice 시뮬레이션을 통해 확인되었으며, 측정된 최대 전압 스트레스는 입력전압의 2.9 배인 170[V]였고 최대 효율은 81.66i%로 측정되었다.