• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.994-998
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• 2004

Hybrid method is used to suppress vibration of an automotive roof surface. The hybrid method proposed in this paper is implemented experimentally using both viscoelastic and piezoelectric material. The piezoelectric material is used to control the vibration of automotive structure for lower range of frequencies and the experiment of vibration control using viscoelastic material has been carried out suppress vibrations of high frequency range mark. At first the plate controlled by using hybrid method has been .implemented to verify the performance for suppressing vibration. Then the experiment has been applied to the automotive roof structure.

• Journal of KSNVE
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• v.2 no.3
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• pp.173-180
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• 1992

A boundary control method that controls interior state by actively controlling the boundary conditions in boundary value problems is proposed for the vibration control of flexible beam by using piezoelectric actuators. The governing equations are derived based on the Euler beam theory and the reduced order model is obtained by modal truncation. The spillover effects caused by the uncontrolled high frequency modes are analyzed and the method selecting a suitable sensor location is also proposed. The lag compensator in digital form is realized by using a microcomputer and its peripheral devices. The efficiency of the proposed control scheme is demonstrated experimentally and compared with the simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.67-75
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• 2007

This paper deals with a problem of vibration suppression of a piezoelectric beam using a self-sensing algorithm. Two methods, which are PPF(positive position feedback) and SRF(strain rate feedback), are considered to suppress a residual vibration of a piezoelectric beam developed during the step positioning of a beam end point. A self-sensing algorithm treated here is basically a strain rate estimator of a beam movement and is to be used for the closed loop control. The efficacy of the proposed idea is evaluated through experiments.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.79-87
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• 2003

Acoustic response control of a comer-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally. Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four comers. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies (0~200Hz), and sound pressure levels (80~100dB) as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.

• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.600-605
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• 2002

In this paper, a Negative Impedance Converter (NIC) circuit was employed for the electro-mechanical characteristic control of a thickness mode piezoelectric vibrator. Two circular plane piezoelectric vibrators were bonded together and the NIC circuit was connected to one of the vibrators. The theoretical and experimental analysis of the characteristics shown that the quality factor and the electro-acoustic efficiency of the vibrator with the NIC circuit could be improved by 20 times and 2.5 times, respectively.

• Journal of KSNVE
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• v.2 no.1
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• pp.49-59
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• 1992

The motion analysis of a translation device driven by a piezoelectric actuator is performed to identify the mechanics of impact drive mechanism and to find the maximum speed waveform. The translation device is modeled as a semidefinite two-degree-of-freedom system. The motion analysis includes effects of friction force between moving mass and contact surface, dynamics of voltage amplifier and piezoelectric elements, and hysteresis of piezoelectric actuator. Base on the model, simulation studies are carried out and then compared with experimental results. It is found that the error between moving distances obtained by analysis and experiment is less than 15% and that the actual motion of moving mass is well predicted by the analytical work, finally, precision positioning experiments are carried out by using a proximity sensor as a feedback sensor. Position control of moving mass is initiated by the maximum speed waveform and finely tuned by the scaled down waveform so that accurate positioning is accomplished within the resolution of the sensor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.266-271
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• 1996

Optimal design of disk shaped piezoelectric actuator and sensor mounted on the plate structure is studied for the control of noise radiated fro the structure. The sensor signal is returned to the actuator through negative gain. Finite element modelling is used for the plate structure and the disk shaped piezoelectric sensor and actuator. The objective function is the total radiated sound power and the design variables are the locations and sizes of the piezoelectric actuator and sensor. The optimal is performed at the resonance and the off resonance frequency and the results show good noise reduction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.633-636
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• 2004

Acoustic response control of a corner-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally. Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four comers. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies $(0\sim200Hz)$, and sound pressure levels $(80\sim100dB)$ as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.474-479
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• 1998

In this paper, we present a mathematical model of the piezoelectric pump and its application to the automobile brake system. The piezoelectric pump consists of a multi-layered piezoelectric element a diaphragm, pumping values, resonant pipes and accumulators, and the maximum pumping power of 62W nab obtained in the previous experiments by using the piezoelectric element of 22mm diameter and 55.5mm length. A detailed mathematical model of the pump is derived here by considering the compressibility of the working oil, nonlinear characteristics of piezoelectric element, the time delay of pumping values' action and be on. The validity of the model is illustrated by comparing the experimental data and the simulation results. Using the mathematical model of the piezoelectric pump, a brake system for automobile disk brake is also simulated in this paper. The brake system consists of a piezoelectric pump as a power source, calipers and its piston to generate brake force, and a three position solenoid value to change the brake situation. It is shown that 15mm/sec of piston speed and 20kN of piston force are obtained by using the piezoelectric element of 33mm diameter and 55.5mm length.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.73-79
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• 2001

In this paper, the transmitted noise reduction performance of piezoelectric smart panels is experimentally studied. The proposed piezoelectric smart panels are comprised of plate structure on which piezoelectric sensor/actuators are bonded and sound absorbing material is provided. It is a combination of passive and active approaches utilizing a passive effect at high frequencies and an active effect at low frequencies. To prove the concept of piezoelectric smart panels, an acoustic measurement experiment is performed. An acoustic tunnel is designed and its acoustic characteristics are tested. Below 800Hz, the tunnel exhibits a plane wave guide characteristics. When an absorbing material is bonded on a single plate, a remarkable transmitted noise reduction in mid frequency range is observed except the first resonance frequency. By enabling the active control of single smart panel with negative feedback control. about 10dB noise reduction is achieved at the resonance frequencies. The double smart panel got 4dB at the first resonance frequency and has more potential to reduce the transmitted noise in a wide range frequency. Piezoelectric smart panels incorporating passive absorbing material and active piezoelectric devices is a promising technology for noise reduction in a wide range frequency.