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RISS 인기검색어
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- 저자 : 한득영 (검색결과 126 건)
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한득영 건국대학교 1990 學術誌 Vol.34 No.2
This paper introduces a technique of changing 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 same sizes and the same properties, respectively. The composite vibrator has shown the characteristics that the fundamental resonant frequency has decreased and spurious nodes lave depressed with increase of the capacitance of the inserted insulator. And the frequency characteristics of the composite vibrator without insulator have been nearly the some as those of each vibrator.
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韓得永 건국대학교 1984 學術誌 Vol.28 No.2
This paper suggests a new type of piezoelectric transformer fabricated with two disks of high Q piezoelectric ceramic resonator and a thin insulator, And an equivalent circuit considering the mechanical loss of the piezoelectric ceramic resonator is described. Also, voltage ratios, current ratios, input impedances, resonant frequencies and an approximate equivalent circuit of the transformer are discussed.
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韓得永 건국대학교 1984 공대학보 Vol.10 No.1
A general equivalent circuit and a lumped circuit near the fundamental resonant frequency of a piezoelectric ceramic disk were discussed. Also, several relationships between the param parameters of the disk ware suggested. Electromechanical comping factor Kt can be calculated from the measured series and perallel resonant frequencies of the disk, and lumped circuit parameters C1, C0, and L1 can be calculated from the Kt and the measured free capacitance of of the disk. The the parameters such as mechanical characteristic impedance Zo, turn ratio N, mechanical quedity factor Om, and material constants cD33, εS33, h33, can be calculated from the radirs r, thicknees 2, density ρ, and the above calculated values of the disk.
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韓得永 건국대학교 부설 산업기술연구소 1984 논문집 Vol.9 No.-
This paper describes the voltage ratios of a new model of piezoelectric ceramic transformer fabricated with two bisected electrode resonators and a thin insulator. In this case of open circuit and resonance, the voltage ratio dependent on the quality factor ?? and the electromechanical coupling factor ?? of resonators, but independent of the thickness and the area of them, and the phase difference between the input voltage and the output voltage is ??. For the high voltage ratio, it is necessary to use the resonators with high ?? and ??.
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한득영 건국대학교 산업기술연구원 1994 건국기술연구논문지 Vol.19 No.-
Expressions for the displacement and the resonant frequency of a bimorph, one end fixed and the other free, have been introduced when sinusoidal imputs of various frequencies were applied to the ceramic plates on a thin metal plate. And maximum displacements at the free end and strains at the position of strain gage attached were measured when various wave forms, voltages, and frequencies were applied to the bimorph whose length is 6.6[cm], width 2.5[cm], and thickness 0.04[cm]. Under the condition of constant frequency and effective length, it was shown that the displacements at the free end and the strains of the gage position were increased as the applied voltage was increased in the range of 30∼90[???]. And it was also found that the resonant frequency of a bimorph was decreased as its effective length was increased, and that the displacements and the strains were maximum at the resonant frequency.
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韓得永,崔圭夏 건국대학교 1984 學術誌 Vol.28 No.2
Static converters with power switching elements have so many advantages as less bulk, fast response, high efficiency and reliability but the harmonics generated by switching operation make worse the power factor and efficiency of the converter-controlled system. Of the several methods to eliminate the harmonics AC current control is the new method that the load current is continuously controlled by the upper and lower limit currents. By this control method the harmonic contents of load current can be greatly reduced and improved the current waveform under the external setting states. In this paper the concept of the switching function is introduced into the current control case and its transfer characteristics are derived and the harmonics of load current are investigated from the digital computation results.
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韓得永 건국대학교 1987 學術誌 Vol.31 No.2
Laminated piezoelectric transformers fabricated with two sets of same piezoelectric disk resonator were studied on their resonant frequencies, bandwidths, and voltage ratios. Their resonant frequencies were dependent on the thickness, clamped capacitance, and turn ratio of the resonators. The bandwidths of those transformers were proportional to the resonant frequencies of resonators and inverse proportional to their mechanical quality factors. Voltage ratios were stable for the wide range of load resistance when the load was far larger than the reactance of the clamped capacitance of the resonator.
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韓得永 건국대학교 부설 산업기술연구소 1980 논문집 Vol.6 No.-
In this paper, the characteristics of sound radiated from the Langevin vibrator made of piezoelectric ceramics Pb(??) O₃+1.0 weight percentage of La₂O₃ and S-45C steel disks were studied. As a result, it was shown that, in case of the same ceramic vibrator and the same thickness of steel disks, the tighter the coupling pressure is, the higher the frequency of the strongest sound is; and that, in case of the same ceramic vibrator and the same coupling pressure, the thicker the steel disks are, the lower the frequency of the strongest sound is. These characteristics can be applied to the design of the Langevin vibrator for sonic or ultrasonic devices.
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압전변압기를 이용한 LCD Backlight용 구동회로의 개발
강태구,안형근,한득영 건국대학교 산업기술연구원 1998 건국기술연구논문지 Vol.23 No.-
This paper describes a driving circuit with a multi-layered piezoelectric transformer(MPT) for the LCD backlight of a portable computer. In order to develop the circuit, we measured at first the L, C, R of the MPT concerned. And, using the measured parameters of L,C,R, we designed and implemented circuits such as a voltage-frequency converter, comparator for tracking resonance frequencies varying when the backlight is turned on, power circuit with two MOSFETs, and triggering circuit with flip/flops. We showed the possibility of tracking the resonance frequency of the MPT under the various load conditions.
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