• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.59-63
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• 2005

Nowadays, various approaches are performed to increase the storage capacity of optical storage device. One of the promising candidates is using the high NA lens. By using high NA lens, the beam spot size can be reduced which will lead to increase the storage density. This paper proposes a double cantilever beam type bimorph PZT actuator for fine motion that can control the gap between the flexible media and optical pickup which uses high NA lens. Mathematical model is derived by using Hamilton's principle and the model is verified by finite element analysis and experiment. Position controller is designed and its performance is evaluated by experiment.

• Advances in aircraft and spacecraft science
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• v.10 no.2
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• pp.179-202
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• 2023

This article presents a numerical analysis to investigate the natural frequencies and harmonic response of a perforated cantilever beam attached to two layers of piezoelectric materials by using the finite element method for the first time. The bimorph piezoelectric is composed of 3 layers; two of them at the outer are piezoelectric, and the inner isotropic material. A higher order 3-D 20-node solid element that exhibits quadratic displacement behavior is exploited to discretize the isotropic layer, and coupled piezoelectric 3D element with twenty nodes is used to mesh the top and bottom layers. CIRCU94 element is added to act as a resistor part of the model. The proposed model is validated with previous works. The numerical parametric studies are presented to illustrate the effects of perforation geometry, the number of rows, the resistance on the natural frequencies, frequency response, and power. It is found that the thickness has a positive relationship with the natural frequency. Perforations help in producing higher voltage, and the best shape is rectangular perforations, and to produce higher voltage, two rows of rectangular perforations should be applied.

• The Korean Journal of Rheology
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• v.3 no.2
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• pp.156-165
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• 1991

폴리비닐리덴플루오라이드 바이모프 외팔보(poly(vinylidene fluoride) bimorph cantilever beam)의 진동을 기술하는 수학적 모형을 세우고 실험으로 그모형의 타당성을 고 찰하였다. 여러 전압의 교류전류에 대해 여러 길이의 외팔보의 주파수응답을 측정하였고 여 러 전압의 직류전류에 대해 여러 길이의 외팔보의 처짐을 측정하였다. 실험으로부터 이 외 팔보의 진동은 점성감쇠보다는 구조감쇠로 기술하는 것이 더 타덩하고 외팔보가 전기장에 대해 damping factor가 일정해야 하나 각각의 normal mode에 대해 다른 damping factor로 수정하여 계산한이론치가 실험과 더 일치하였다. 공명주파수의 공명진폭을 예측할수 있고 넓은 입력주파수 영역에 대한 외팔보의 응답을 기술 할수 있으며 진동하는 외팔보는 모든위 치에서의 진폭을 기술할수 있다는 점에서 여기서의 모형은 Toda와 Smits의 모형들보다 우 수하다고 볼수 있다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.822-824
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• 2003

본 논문에서는 압전체의 3차원 유한 요소 해석을 통해 압전체의 공진 특성을 해석하였으며 이를 실험적으로 검증하였다. 검증된 유한요소법을 압전 외팔보(Piezoelectric Bimorph cantilever)에 적용하여 임피던스 해석을 수행하였으며 실험 결과와 비교하여 해석의 타당성을 검증하였다. 또한 팬용 압전 외팔보의 공진 특성 해석을 통해 공진 주파수, 변위 및 편향각을 계산하였다. 이를 통해 펀용 압전 외팔보의 적용 가능성을 확인하였다.

• Smart Structures and Systems
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• v.16 no.5
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• pp.759-780
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• 2015

Based on the theory of piezoelasticity, the static performance of a piezoelectric bilayer cantilever fully covered with electrodes on the upper and lower surfaces is studied. Three models are considered, i.e., the sensor model, the driving displacement model and the blocking force model. By establishing suitable boundary conditions and proposing an appropriate Airy stress function, the exact solutions for piezoelectric bilayer cantilevers are obtained, and the effect of ambient thermal excitation is taken into account. Since the layer thicknesses and material parameters are distinguished in different layers, this paper gives unified solutions for composite piezoelectric bilayer cantilevers including piezoelectric bimorph and piezoelectric heterogeneous bimorph, etc. For some special cases, the simplifications of the present results are compared with other solutions given by other researches based on one-dimensional constitutive equations, and some amendments have been found. The present investigation shows: (1) for a PZT-4 piezoelectric bimorph, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are about 19.59%, 23.72% and 7.21%, respectively; (2) for a PZT-4-Al piezoelectric heterogeneous bimorph with constant layer thicknesses, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are 9.85%, 11.78% and 4.07%, respectively, and the amendments of the electrode charges induced by an end shear force or an end moment are both 1.04%; (3) for a PZT-4-Al piezoelectric heterogeneous bimorph with different layer thicknesses, the maximum amendment of tip deflection approaches 23.72%, and the maximum amendment of electrode charge approaches 31.09%. The present solutions can be used to optimize bilayer devices, and the Airy stress function can be used to study other piezoelectric cantilevers including multi-layered piezoelectric cantilevers under corresponding loads.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.6
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• pp.661-668
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• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.927-931
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• 2005

Carbon nanotube actuator, working under physical conditions (in aqueous solution) and converting electrical energy into mechanical energy directly, can be a good substitute for artificial muscle. The carbon nanotube actuator simulated in this paper is an isotropic cantilever type with an adhesive tape which is sandwiched between two single-walled carbon nanotubes. For predicting the static and dynamic characteristic parameters, the analytical model for a 3 layer bimorph carbon nanotube actuator is developed by using Euler-Bernoulli beam theory. The governing equation and boundary conditions are derived from energy principles. The induced displacements of the theoretical model are presented in order to investigate the performance of the carbon nanotube actuator with different control voltages. The developed model presents invaluable means for designing and predicting the performance of carbon nanotube actuator that can be used in artificial muscle applications.

• 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 Mechanical Science and Technology
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• v.18 no.4
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• pp.622-629
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• 2004

In this paper, effects of elastic energy of magnetostrictive film on the deflection of a cantilevered film-substrate system are investigated. The total energy including the elastic energy of magnetostrictive film is formulated. And it is minimized to give the curvatures and the position of neutral axis of the cantilevered system. To discuss the effects of the elastic energy of film in a measured system, three magnetostrictive unimorph cantilevers and a bimorph cantilever reported elsewhere are reviewed. It is shown that the assumption, since the thickness of film is much smaller than that of substrate the film elastic energy is negligible, can cause considerable error in evaluating magnetostrictive coefficients. Not the ratio of thicknesses but elastic energies between film and substrate is also shown to play important role in making decision whether the assumption is valid or not.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.206-211
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• 2010

Piezoelectric energy harvesting uses piezoelectric, which is able to convert unused mechanical vibration energy to electrical energy, such as with motor and machinery. The piezoelectric energy harvester was constructed with a cantilever made of lead zirconate titanate with a metal plate. The primary material was soft lead zirconium titanate (PZT-5H) due to the large strain availability, acceptable mechanical strength and high piezoelectric constant. This technique's drawback is that the energy efficiency is lower than the other energy harvesting methods, but this study increases the output electric power efficiency by analyzing a finite element method for the structure of the piezoelectric energy harvester. We manufactured two cantilever types as follows: the L-60 and L-33 bimorph piezoelectric energy harvesters. Their resulting energy harvesters were able to obtain high voltage values as follows: 27.4 mV and 40.6 mV. Moreover, these results have a similar band of resonance frequency it comparison to the simulation. Consequently, this study was confirmed with validity. The output electric powers of the L-60 and L-33 types have 3.1 mW/s and 5.8 mW/s with 47 Hz and 148 Hz of resonance frequency and then, the load resistivities were $100k\Omega$ and $10k\Omega$, respectively.