• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.5
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• pp.411-417
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• 2007

This study has been conducted to investigate pumping characteristics of diffuser/nozzle based piezoelectric micropumps. The micropumps include a piezo disk (an actuator), a chamber and a set of diffuser and nozzle. Flow in the current micropumps is controlled by a set of diffuser and nozzle, not by a nap valve. The diffuser/nozzle based micropumps are more reliable in operation and are easier in manufacturing than the flap valve based micropumps. The flow rates of the piezoelectric micropumps have been closely analyzed with a numerical calculation. It has been found that the positions of the inlet and outlet of the micropump can influence the performance of the diffuser/nozzle based piezoelectric micropumps. This study may provide fundamental understanding for the design and analysis of the piezoelectric micropumps.

• Journal of KSNVE
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• v.8 no.2
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• pp.267-273
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• 1998

This study aims at performing sensitivity analysis of piezoelectric smart structure for minimizing radiated noise from the structure, The structure consists of a flat plate on which disk shaped piezoelectric actuator is mounted, and finite element modeling is used for the structure. The finite element modeling uses a combination of three dimensional piezoelectric, flat shell and transition elements so thus it can take into account the coupling effects of the piezoelectric device precisely and it can also reduce the degrees of freedom of the finite element model. Electric potential on the piezoelectric actuator is taken as a design variable and total radiated power of the structure is chosen as an objective function. The objective function can be represented as Rayleigh's integral equation and is a function of normal displacements of the structure. For the convenience of computation, all degrees of freedom of the finite element equation is condensed out except the normal displacements of the structure. To perform the design sensitivity analysis, the derivative of the objective function with respect to the normal displacements is found, and the derivative of the norma displacements with respect to the design variable is calculated from the finite element equation by using so called the adjoint variable method. The analysis results are compared with those of the finite difference method, and shows a good agreement. This sensitivity analysis is faster and more accurate than the finite difference method. Once the sensitivity analysis program is used for gradient-based optimizations, one could achieve a better convergence rate than non-derivative methods for optimal design of piezoelectric smart structures.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.179-180
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• 2008

In this paper, the variable tendency piezoelectric constant and resonance characteristics piezoelectric ceramics due to the electric field is studied. The practical application of piezoelectric ceramics is not only applied in field of small signal. For example, in case of an ultrasonic motor, $120{\sim}130Vrms$ of driving voltage is needed and that of an piezoelectric pump, $200{\sim}220Vrms$ of voltage is required. Therefore, to examine the characteristics of piezoelectric ceramics in large signal contributes to reducing the susceptibility to the multifarious application and securing the ease of the production of control circuit. These contributions may be connected to the expansion of industrial application. We fabricated disk-type piezoelectric ceramic samples by using conventional method and measured the resonance characteristics of these samples under from low to high voltage driving conditions. According to increasing the value of the input voltage, we measured the resonance frequency of the piezoelectric ceramic, and inquired into the cause of these phenomena.

• Advances in nano research
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• v.12 no.6
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• pp.567-581
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• 2022

The free and forced vibration in addition to electric energy harvesting of a piezoelectric disk resting on two-parameter foundation modeled by modified couple stress as well as Kirchhoff plate theory is probed. The governing equations and boundary conditions are obtained using Hamilton's principle. Then, the free and forced vibration are solved using numerical solutions, generalized differential quadrature method (GDQM) and Newmark-beta method. The forced vibration is resulted from a base excitation load. Also, the possible voltage which can be harvested from this system is obtained using generalized integral quadrature method. The validity of the formulation and solution procedure is confirmed using a compassion study. The impact of parameters such as length effect, inner to outer radius ratio, and foundations parameters on the free and forced vibration as well as energy harvesting is investigated in detail. This paper can be a basis for future studies in the area of piezoelectric harvesters in small scales.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.194-201
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• 1998

The beam rotating actuator has been developed. It can be utilized to improve the data transfer rate for the optical disk systems, Newly developed laser beam rotating actuator is applied to put multi-beam spots on more than one track on the optical disk simultaneously. The beam rotating actuator is made of piezoelectric ceramic bimorph as the form of cantilever, Piezoelectric actuators with high resolution, high stiffness and fast frequency response are widely assembled in micropositioning applications. Therefore, the actuator has above 50Hz natural frequency. Beam array is rotated using the dove prism in the end of beamrotator. The dynamic equation of beam rotating actuator is derived theoretically. The actuator is designed on the ground of this analysis. The performance of the beam rotating actuator is verified as the dynamics frequency performance is measured using the dynamic analyzer and sensor.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.203-208
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• 2001

In this paper, a novel dual-type positioning mechanism using a voice coil motor(VCM) and a piezoelectric actuator is proposed for optical disk drive or near-field recording type drive. The VCM is used for a coarse motion actuator and the piezoelectric actuator, "S" configuration deflection motion when voltage applied, is used for a fine motion actuator with self-sensing technique, which allows it to sense and actuate simultaneously in a closed loop frame work. When the VCM rotates and stops, a position feedback control algorithm is adopted to further control residu vibration. The performance of the control scheme is confirmed through simulations and experiments.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.333-334
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• 1989

Electrically active part of the piezoelectric sound element is a ceramic thin circular disk cemented to a metal base plate (using a type of thermosetting epoxy). The active part is a thin lead zirconate titanate disk (PZT). The piezoelectric sound element is so dimensioned that its basic resonance frequency is approximately if the center of the audible frequency band: This frequency is mainly determined by the geometry and the sort of the metal base plate materials. In this study, four kinds of PZT ceramic and two classes of thin metal base plate were prepared. It is observed that dielectric and pizoelectric properties relate to acoustical properties (particularly sound pressure level).

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.175-176
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• 2008

An ultrasonic motor of high torque with a new configuration for application in automobiles is proposed. The newly designed stator is two sided vibrator consisting of a toothed metal disk with a piezoelectric ceramic ring bonded on both faces of the disk which generates a flexural traveling wave along the circumference of disk. In this configuration, the displacement on the surface of stator may not be confined. It also produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric plates. It is possible to increase the torque by improving the vibration characteristics. To compute the vibration mode of the motor of diameter 48 mm, the finite element method was used. A 6th mode was chosen as the operation mode with a resonance frequency of about 64.4 kHz. According to this design and measured its performance, a prototype was fabricated. The performance measurement of the prototype motor showed that its stall torque was about 1.8 Nm and efficiency was 37 % at 60 % of the maximum torque.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.187-188
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• 2008

An ultrasonic motor of high torque with a new configuration for application in automobiles is proposed. The newly designed stator is a two sided vibrator consisting of a toothed metal disk with a piezoelectric ceramic ring bonded on both faces of the disk which generates a flexural traveling wave along the circumference of disk. In this configuration, the displacement on the surface of stator may not be confined. It also produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric plates. It is possible to increase the torque by improving the vibration characteristics. To compute the vibration mode of the motor of diameter 48 mm, the finite element method was used. A 6th mode was chosen as the operation mode with a resonance frequency of about 64.4 kHz. According to this design and measured its performance, a prototype was fabricated. The performance measurement of the prototype motor showed that its stall torque was about 1.8 Nm and efficiency was 37% at 60% of the maximum torque.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.722-723
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• 2013