• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1337-1338
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• 2007

In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, 0.07Pb$(Mn_{1/3}Nb_{2/3})O_{3}-xPb(Ni_{1/3}Nb_{2/3})O_{3}-(0.93-x)Pb(Zr,Ti)O_{3}$ ceramics system were fabricated using $Li_{2}CO_{3}-Bi_{2}O_{3}$-CuO sintering aids and the specimens were sintered at $930^{\circ}C$. Thereafter their piezoelectric and dielectric characteristics were investigated with the amount of PNN substitution. At 9[mol%] PNN substitution, electromechanical coupling factor (kp), mechanical quality factor (Qm) and piezoelectric constant ($d_{33}$) showed the optimum value of 0.60, 1323 and 387pC/N, respectively.

• 전력전자학회논문지
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• 제14권1호
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• pp.62-71
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• 2009

본 논문에서는 마이크로 변위제어 시스템의 적층형 압전 액츄에이터를 위한 스위칭 증폭 구동회로의 구동방법을 제시하고 성능을 평가하였다. 이 증폭기는 압전 액츄에이터로부터 임의의 용량성 부하에 저장된 에너지를 효율적으로 회수할 수 있는 장점이 있다. 기존의 전압 되먹임 제어 방식은 100mHz의 정현파 기준치 추종시, 총 왜곡율이 -32dB (${\approx}2.5%$)로서, 액츄에이터의 전압과 변위 사이의 비선형적 관계로 인한 오차발생을 확인할 수 있었다. 이를 개선하기 위하여 전하 제어방식을 살펴보았는데, 기존의 직렬 커패시터를 연결하는 대신, 변위 기준치를 미분하고, 이를 출력전류와 비교하는 방식으로 개선하였다. 전하량 되먹임 제어 적용시 변위의 왜곡률은 약 -52dB (${\approx}0.25%$)로서 선형성이 매우 우수한 특성을 보임을 알 수 있다. 마지막으로 살펴본 직접 변위 제어 방식은 구현상의 복잡성으로 성능의 한계가 존재함을 알 수 있다.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1104-1111
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• 2011

This paper investigates the filtered velocity feedback(FVF) controller for the reduction of the acoustic power radiated from a clamped beam. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be sorted out. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function(OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide bandbelow the tuning mode of the FVF controller.

• 한국전기전자재료학회논문지
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• 제11권11호
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• pp.963-968
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• 1998

The stress distribution in multilayer piezoelectric ceramic actuators was investigated by Finite element analysis. The y direction stress was concentrated at electrode tip. The y direction maximum stress was decreased to 4.9$\times10^ 7 N/m^2$ with internal electrode gap(a) until 0.4 mm and was not much difference with external electrode thickness(c). The stress distribution with internal layers was almost same and the stress distribution of load condition was higher than that of no load condition The y direction maximum stress increased with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution was disconnected around the defect and larger than that of normal actuator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.329-332
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• 1991

In this studies, variation of the sintering temperature with a single round type piezoelectric actuator of PZT 401 powder [UPI CO.] were fabricated. The piezoelectric properties were investigated as specimens with sintering temperature $1000^{\circ}C,\;1100^{\circ}C,\;1200^{\circ}C,\;1270^{\circ}C,\;1300^{\circ}C$. The strain was measured with respect to the variation of the electric field(500V-1000V), time, temperature($18^{\circ}C-40^{\circ}C$) and humidity(35%-93%).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1038-1041
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• 2004

In this study, developed a micro-level experimental setup to measure pore pressure and poroelastic modulus in various strain and strain rate about a stress in micro-structure of bone tissue. It is essential device in the development of the model to analysis the interstitial bone fluid flow of the lacuno-canalicular system to be known that would effect on the bone remodeling. The constitution of the experimental setup is as follows, microscopic image processing system; actuator control unit; load measurement system. A pilot study was used an artificial chemical wood to have similar poroelastic property of bone matrix and conducted to validate the suitability of the measurement system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1570-1576
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• 2000

하드디스크의 고용량화 추세에 따라 헤드의 정밀한 위치제어를 위한 큰 대역폭의 트랙추적 서보 시스템의 필요성이 대두되고 있다. 이에 작은 신호의 마찰을 제거하고 대역폭을 높이는 방법 중 하나인 2단구동기 트랙추적제어를 실시하여 큰 대역폭의 트랙 추적 서보시스템을 구성하는 방법에 대해 연구하였다. 2단구동기는 조동구동기(기존 하드디스크의 VCM)와 전단형 압전체를 부착한 미동구동기로 구성하였다. 미동구동기의 Hinge구조는 트랙 방향의 공진 주파수와 출력변위를 만족시키기 위한 구조로 설계하였다. 제어기는 notch filter와 PI 보상기를 사용하는 조동구동기와 notch filter와 PD 보상기를 사용하는 미동구동기를 다양한 구조로 구성한 것들을 비교하였다. 2단구동기는 VCM만을 사용하여 트랙 추적을 할 때보다 트랙 편심을 잘 추적하며, 기계적 공진과 VCM의 비선형성에 의해 제한된 대역폭을 개선시키는 효율적인 방법임을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.377-383
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• 2011

This paper reports the filtered velocity feedback (FVF) controller to reduce the acoustic power from clamped beams. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be resolved. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function (OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide band below the tuning mode of the FVF controller.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.434-439
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• 1997

This paper presents the active control of a flexible plate vibration. The plate was excited by white noise point force and the control was performed by one or two piezo ceramic actuator bonded to the surface of the plate. An adaptive controller based on filtered-x or multiple filtered-x LMS algorithm was used and the controller was defined by minimizing the square of the response of error sensor. In the experiment, PZT sensor was used as an error sensor while white noise was applied as a disturbance. In the case of multiple channel control, more than 22 dB of vibration reduction was achieved. Results indicate that the vibration of a flexible plate could be controlled effectively when the piezo ceramic actuator was used with multiple filtered-x LMS algorithm.

• 한국정밀공학회지
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• 제21권3호
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• pp.155-162
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• 2004

This paper presents the fabrication procedure and the experiments for the 3-axis fine positioning stage proposed in［1］. First, the dynamic characteristics of the actuator and the stage are tested with the preload changed in order to validate the stage design specifications. Secondly, the performance of the stage is also evaluated on the accuracy associated with linear positioning, angular error, and straightness error. Experimental results show that the developed stage is accurate enough to be used for nanometer positioning. Through the analysis and experiment, the developed fine positioning stage are found to have a long stroke due to the magnetically preloaded PZT actuators, the minimum motion crosstalk due to the use of a ball contact mechanism and the compact design.