• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.119-120
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• 2008

Using the extensional vibration mode of PZT bar, a piezopump is successfully made. The traveling extensional wave along the circumference of the bar is obtained by dividing standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic bar.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.529-533
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• 2000

This paper present a new sort of multilayer piezoelectric ceramic transformer for AC-adapt. This piezoelectric transformer operates n the second thickness extensional vibration mode. The output voltage of the multilayer piezoelectric transformer was simulated using ANSYS. As results, the maximum stress appeared at the two points where one is the middle of input and the other is middle of output side in Second thickness extensional vibration mode. And output voltage was inversely decreased by increasing number of output layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.31-38
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• 2004

PMN-PT, a piezoelectric single crystal, has many useful applications such as sensors and actuators. In this paper, all the elastic, piezoelectric, and dielectric constants of the PMN-32％PT single crystals were measured by the resonance method. For the rhombohedral symmetry, a total of twelve independent material constants were measured such as six elastic compliance constants at constant electric field, two dielectric constants at constant stress, and four piezoelectric constants d. Seven sets of crystal samples of each different geometry were prepared for the measurement of length-thickness extensional, thickness extensional, radial, length extensional and thickness shear modes of vibration, respectively. In order to check the validity of the measurement, experimental impedance spectrum of the PMN-PT crystal was compared with numerical data spectrum calculated with the measured material constants. The good agreement between the two spectra confirmed validity of the results in this paper.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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• pp.858-864
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• 2002

Aging stabilities of the operating frequency of piezoelectric devices such as filter, oscillator and discriminator are very important. In this study it was studied aging stabilities of the length-extensional vibration mode of Pb(Zr$\^$y/O$_3$+ x[wt%]Cr$_2$Co$_3$ ceramics. PZT ceramics in morphotropic phase boundary have higher aging rates of k$\_$31/ and resonance frequency than those in tetragonal phase or rhombohedral phase. Thermal aging moves the composition with maximum aging rate to Zr-rich side in Cr$_2$O$_3$ not added PZT system. In the PZT system, aging rates of k$\_$31/ and resonance frequency for first 30 days are bigger than those for the following 90 days. Thermal aging decrease those for first 30 days. Aging rate of resonance frequency of the ceramics with x=0.1, y=0.53 and x=0.3, y=0.53 increased by thermal aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.70-73
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• 2000

This paper present a new sort of multilayer piezoelectric ceramic transformer for AC-adapter. This piezoelectric transformer operates in the second longitudinal vibration mode. The output voltage of the multilayer piezoelectric transformer was simulated using ANSYS, that is one of the FEM analysis program. As results, the minimum displacement was occurred at the two paints where one is the middle of input and the other is middle of output side in second thickness extensional vibration mode. And output voltage was inversely decreased by increasing number of output layers. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.322-322
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• 2010

In this paper, we propose a novel type valveless micro-pump that uses extensional vibration mode of traveling wave as a volume transporting means for solving some problems about check valves, essential parts of usual pumps. The proposed pump consists of two piezoelectric ceramic rings and a metal body located in the middle of them respectively. Because the drift of bended surface that results from the traveling wave excitation controls the fluid flow, check valves are not needed in this pump model. In accordance with the variation of the pump body dimension, we analyzed the vibration displacement characteristics of pump model, determined the optimal design condition, fabricated the prototype pump from the analysis results and evaluated its efficiency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.5
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• pp.437-446
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• 2011

Performance of array sonars towed underwater is limited due to the self-noise induced mainly by the strumming vibration of the towing cable and also turbulent flow around the acoustic sensor module. The vibration of the towing cable generates axisymmetric waves that propagate along the acoustic module of the array sonar and produce self-noise. The present study aims to investigate the characteristics of the self-noise induced by the axisymmetric vibrations of the acoustic module. The waves of interest are the bulge and extensional waves propagating along the fluid-filled elastic hose. Dispersion relations of these waves are predicted by means of the numerical simulation to evaluate the wave speeds. The self-noise induced by the axisymmetric waves are formulated taking into account the damping of the elastic hose and the effect of the damping is investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.109-114
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• 2002

Aging stabilities of the operating frequency of piezoelectric devices such as filter, oscillator and discriminator are very important. In this study it was studied aging stabilities of the length-extensional vibration mode of Pb(Zr$\_$y/Ti$\_$1-y/)O$_3$+x[wt%]Cr$_2$O$_3$ ceramics. PZT ceramics in Morphotropic phase boundary have higher aging rates of k$\_$31/ and resonant frequency than those in tetragonal phase or rhombohedral phase. Thermal aging moves the composition with maximum aging rate to Zr-rich side in Cr not added PZT system. Aging rate of resonant frequency of the ceramics with x=0.1, y=0.53 and x=0.3, y=0.53 increased by thermal aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.215-216
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• 2008

Using the extensional vibration mode of PZT ring, a piezopump is successfully made. The PZT ring is polarized with thickness direction. The traveling extensional wave along the circumference of the ring is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic ring.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.804-810
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• 2000

In this paper, an experimental identification method is presented to identify the bulge wave and extensional wave propagation speeds in the fluid-filled elastic hose. An fluid-filled hose is hanged vertically for straight position. The exciting device of piston type is developed to generate the bulge wave and extensional wave in the elastic hose. Hydrophones are arranged in the fluid-filled hose linearly to measure the wave pressure. The wave speeds are estimated using the wavenumber-frequency spectrum analysis technique.