• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.33-34
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• 2005

In this study, in odor to develop low temperature sintering multilayer piezoelectric actuator and ultrasonic vibrator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated according to the addition of dopant CuO and $Fe_2O_3$, respectively. The CuO added PMN-PNN-PZT ceramics improved mechanical quality factor Qm due to the acceptor doping effect. And also, $Fe_2O_3$ reacted as softner in this composition system in addition to the increase of grain size and sinterability. Taking into consideration electromechanical coupling factor kp of 0.62, dielectric constant $\varepsilon_r$, of 1275, Piezoelectric $d_{33}$ constant of 377[pC/N] and mechanical quality factor Qm of 975, it was concluded that the ceramics with the $Fe_2O_3$, added composition sintered at 900[$^{\circ}C$] were best for the multilayer piezoelectric actuator and ultrasonic vibrator application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.301-302
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• 2007

Energy harvesting from the vibration through the piezoelectric effect has been studied for powering the wireless sensor node. For the driving wireless sensor node, the generated energy is required to store the capacitor or battery. For the rapid charging, higher voltage than battery's capacity voltage and a large current are necessitated. However, the piezoelectric energy harvester is generally featured as a high voltage and low current generator. As it is known that the generated current in the piezoelectric energy harvester is related to an area of electrode of piezoelectric ceramics, we fabricated the multilayer ceramics to increase effective area for the faster charging. The energy harvesting properties and charging characteristics of multilyaer ceramics were investigated and discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.918-921
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• 2005

According to the mechanical-electrical coupling characteristics and the electrical Impedance property of resistor-inductor-capacitor(RLC) series resonant circuit, the mechanical impedance analysis of a bimorph piezoceramic patch shunted with a series RLC resonant circuit is conducted. The displacement transfer function of a cantilever beam bonded with a piezoelectric shunt damping module is deduced in the case of single mode vibration of the beam. By the use of vibration damping theory of tuned mass damper system, the parameter optimization of piezoelectric shunt damping system is performed. The optimal resonant state of the shunting circuit can be obtained when the resister and conductor are optimally adjusted. Test results show that the vibration control effect as well improved with optimized piezoelectric shunt system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.403-406
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• 2004

In this paper, the design of damped structures associated with the piezoelectric shunt circuits is undertaken and it is applied to optical disk drive (O.D.D) main base in order to reduce unwanted vibration. In order to design effective piezoelectric structure, the admittance of the structure is introduced as the performance index of the piezoelectric shunt system. And the admittance offset of the shunt performance is theoretically investigated. It is also presented that the admittance can be calculated by commercial finite elements program. To verify the admittance calculated by F.E.M, admittance measurement is performed by impedance analyzer. In this verifying process, the validity of the finite element admittance analysis is found. As a practical approach, to reduce the vibration of the O.D.D. main base, piezoelectric shunt system is designed using the proposed admittance analysis and shunt effect is evaluated at all prescribed frequencies.

• 한국전산구조공학회논문집
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• 제25권1호
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• pp.91-99
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• 2012

본 연구에서는 PZT 소자의 정압전 효과에 의한 동적 응답신호를 이용하는 보 구조물 손상 모니터링 기법을 제안하였다. 특히, 모드 변형에너지기반 보 구조물 손상 모니터링에 PZT 정압전 응답신호를 입력자료로 활용하는 방안에 대한 연구에 주안점이 있다. 먼저, PZT 소자의 정압전 효과 및 동적 변형률 응답의 이론적 배경을 요약하였다. 다음으로, 모드 변형에너지기반 보 구조물 손상위치 모니터링 기법을 제시하였다. 제시된 기법의 적합성을 검증하기 위해, 캔틸레버 보 모형을 대상으로 강제진동 실험을 수행하였으며, 세 종류의 센서(가속도계, PZT 센서, 변형률계)를 통해 동적 응답신호가 계측되었다. 손상 전후에 계측된 이들 진동신호들을 사용하여 모드 변형에너지기반의 손상위치 모니터링이 수행되었다.

• 항공우주시스템공학회지
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• 제12권5호
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• pp.54-68
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• 2018

본 논문에서는 소형 압전유압펌프에 적용된 체크밸브의 동적 특성이 유량 형성에 미치는 효과에 대한 연구를 수행하였다. 브레이크 시스템 작동을 위한 부하 압력의 형성을 위해서는 압전유압펌프의 유량이 중요한 요소이다. 이때, 유체 내에서 작동하는 체크밸브의 고유 진동수는 압전 유압펌프의 유량 형성에 큰 영향을 미친다. 또한, 체크밸브의 고유 진동수는 체크밸브와 펌프 시트 사이의 간격에 영향을 받는다. 이를 고려하여 본 연구에서는 체크밸브와 펌프 시트 사이의 간격에 따른 체크밸브의 고유진동수를 유체-구조 연성 해석을 통해 산출하였다. 시뮬레이션을 통해 얻은 유량은 개발된 압전유압펌프를 이용한 유량 형성 실험과의 비교를 통해 검증하였다.

• 한국재료학회지
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• 제11권6호
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• pp.498-501
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• 2001

0.9Pb($Mg_{1/3}Nb_{2/3}$)$O_3$-0.1Pb$TiO_3$계 완화형 강유전체에서 MnO$_2$ 첨가가 압전물성에 미치는 영향을 강유전성이 우세한 온도영역인 -40~3$0^{\circ}C$의 온도범위에 걸쳐 조사하였다. MnO$_2$ 첨가에 의한 효과를 유전특성, 압전특성, 전계유기 변형특성 등의 영역에서 고찰하였다 MnO$_2$ 첨가량이 증가할수록 유전성 및 압전성은 hard piezoelectric의 경향을 나타내었다. 이러한 실험적 고찰로부터 첨가된 Mn은 강유전 도메인 분역을 고정하는 역할을 하는 것으로 제안되었다.

• Smart Structures and Systems
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• 제20권6호
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• pp.709-728
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• 2017

This disquisition proposes a nonlocal strain gradient beam theory for thermo-mechanical dynamic characteristics of embedded smart shear deformable curved piezoelectric nanobeams made of porous electro-elastic functionally graded materials by using an analytical method. Electro-elastic properties of embedded curved porous FG nanobeam are assumed to be temperature-dependent and vary through the thickness direction of beam according to the power-law which is modified to approximate material properties for even distributions of porosities. It is perceived that during manufacturing of functionally graded materials (FGMs) porosities and micro-voids can be occurred inside the material. Since variation of pores along the thickness direction influences the mechanical and physical properties, so in this study thermo-mechanical vibration analysis of curve FG piezoelectric nanobeam by considering the effect of these imperfections is performed. Nonlocal strain gradient elasticity theory is utilized to consider the size effects in which the stress for not only the nonlocal stress field but also the strain gradients stress field. The governing equations and related boundary condition of embedded smart curved porous FG nanobeam subjected to thermal and electric field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is utilized to achieve the natural frequencies of porous FG curved piezoelectric nanobeam resting on Winkler and Pasternak foundation. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality parameter, electric voltage, coefficient of porosity, elastic foundation parameters, thermal effect, gradient index, strain gradient, elastic opening angle and slenderness ratio on the natural frequency of embedded curved FG porous piezoelectric nanobeam are successfully discussed. It is concluded that these parameters play important roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.

• Smart Structures and Systems
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• 제9권6호
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• pp.505-534
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• 2012

The present work deals with second order statistics of post buckling response of piezoelectric laminated composite cylindrical shell panel subjected to hygro-thermo-electro-mechanical loading with random system properties. System parameters such as the material properties, thermal expansion coefficients and lamina plate thickness are assumed to be independent of the temperature and electric field and modeled as random variables. The piezoelectric material is used in the forms of layers surface bonded on the layers of laminated composite shell panel. The mathematical formulation is based on higher order shear deformation shell theory (HSDT) with von-Karman nonlinear kinematics. A efficient $C^0$ nonlinear finite element method based on direct iterative procedure in conjunction with a first order perturbation approach (FOPT) is developed for the implementation of the proposed problems in random environment and is employed to evaluate the second order statistics (mean and variance) of the post buckling load of piezoelectric laminated cylindrical shell panel. Typical numerical results are presented to examine the effect of various environmental conditions, amplitude ratios, electrical voltages, panel side to thickness ratios, aspect ratios, boundary conditions, curvature to side ratios, lamination schemes and types of loadings with random system properties. It is observed that the piezoelectric effect has a significant influence on the stochastic post buckling response of composite shell panel under various loading conditions and some new results are presented to demonstrate the applications of present work. The results obtained using the present solution approach is validated with those results available in the literature and also with independent Monte Carlo Simulation (MCS).

• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.445-451
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• 2022

Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O₃ (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr_1-xTi_x)O₃-0.1 Pb(Zn_1/3Nb_2/3)O₃ (PZT_x-PZN) ceramics with various grain sizes were investigated. PZT_x-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.