• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.437-437
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• 2000

It is more difficult to accurately weigh vehicles in motion than to weigh standing vehicles. The difficulties in weighing vehicles result from sensor Limitations as well as dynamic effects induced by vehicle/pavement interactions, This paper presents a method for improving the accuracy of measured axle load information using the so-called adaptive footprint tire model. The total vehicle weight as well as individual axle weight information are obtained experimentally using two piezoelectric sensors. Results are obtained for a light car, mid-site passenger car, and 2 dump trucks with known weight experimental results show that the proposed method using the tire model is accurate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.322-325
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• 2002

In this study, dielectric and piezoelectric properties of PSN-PZT Ceramic were investigated as a function of PNW substitution. With the increase of PNW substitution, teragonality, Curie temperature and mechanical quality factor were decreased but grain size and electromechanical coupling factor(kp) was gradully increased. At 4 mol [%] PNW substitution. maximum kp of 0.567 was shown.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.680-683
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• 2011

This study deals with damage detection in beam structure by using modal strain energy-based technique with three different sensor types: accelerometer, lead zirconate titanate (PZT) piezoelectric sensor and electrical strain gage. First, the use of direct piezoelectric effect of PZT sensor for dynamic strain response are presented. Next, a modal strain energy-based damage detection method is outlined. For validation, forced vibration tests are carried out on lab-scale aluminum cantilever beam. The dynamic responses are measured for several damage scenarios. Based on damage localization results, the performance of three different sensor types is evaluated.

• Smart Structures and Systems
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• v.22 no.4
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• pp.369-382
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• 2018

Novel design of interdigitated electrodes capable of increasing the performance of piezoelectric transducers are proposed. The new electrodes' geometry improve the electromechanical coupling by offering an enhanced adaptation of the electric field to the interdigitated electrode configuration. The proposed analysis is based on finite element modeling and takes into account local polarization effect. It is shown that the proposed electrodes considerably increase the strain generation compared to flat electrode arrangement used for Macro Fiber Composite (MFC) and Active Fiber Composite (AFC) actuators. Also, electric field singularities are reduced allowing better reliability of the transducer against electric failure.

• Smart Structures and Systems
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• v.25 no.6
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• pp.643-655
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• 2020

Active control of nonlinear vibration of stiffened functionally graded (SFG) cylindrical shell is studied in this paper. The system is subjected to axial and transverse periodic loads in the presence of thermal uncertainty. The material composition is considered to be continuously graded in the thickness direction, also these properties depend on temperature. The relations of strain-displacement are derived based on the classical shell theory and the von Kármán equations. For modeling the stiffeners on the cylindrical shell surface, the smeared stiffener technique is used. The Galerkin method is used to discretize the partial differential equations of motion. Some comparisons are made to validate the SFG model. For suppression of the nonlinear vibration, the linear and nonlinear control strategies are applied. For control objectives, the piezoelectric actuator is attached to the external surface of the shell and the thin ring piezoelectric sensor is attached to the middle internal surface of shell. The effect of PID, feedback linearization and sliding mode control on the suppression of vibration for SFG cylindrical shell is presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.877-880
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• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the substrate effect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration.

• Electrical & Electronic Materials
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• v.7 no.5
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• pp.417-424
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• 1994

PbNb$_{2}$O$_{6}$ piezoelectric ceramics have good properties, but the applications of them have been limited due to the problems of microstructures. In the present study, effects of additives on the phase stability, microstructure, and electrical proper-ties of ferroetectric phase were investigated. La$_{2}$O$_{3}$, Nd$_{2}$O$_{3}$ and Sm$_{2}$O$_{3}$ were added with the amounts of 1, 3, 5 mol% respectively. The results showed that single orthorhombic(ferroelectric phase) phase compared with the mixed phase of pure PbNb2O6 was obtained. In the case of 5 mol% Nd$_{2}$O$_{3}$ addition, relative density of >95% and dense microstructure with -2.mu.m grain size were obtained.d.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1554-1555
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• 2007

본 논문에서는 기존의 Piezoelectric micropower generator 연구에서 주로 사용되던 Schottky 다이오드 대신 역방향 누설전류가 아주 작은 PAD1과 같은 다이오드를 사용함으로써 기계적 에너지로부터 전기적 에너지로의 에너지 변환효율을 획기적으로 증가시킬 수 있음을 확인하였다. 시뮬레이션을 위해 실험결과를 초기 값으로 한 최적화된 등가회로를 구성하였으며, 실험과 PSPICE 시뮬레이션을 통해 분석한 결과 에너지 변환효율은 최고 100% 이상 증가됨을 알 수 있었다. 특히 미세한 진동으로부터의 매우 작은 기계적 에너지를 이용하는 경우에는 PAD1과 같이 역방향 누설전류가 아주 작은 다이오드를 이용해야만 전기에너지로의 변환이 가능함을 증명하였다.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.374-379
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• 2018

The piezocomposite transducer is widely used because it is highly efficient in transforming electric energy into mechanical energy, and its frequency range is broader than that of other types of ultrasound transducers. A general piezocomposite transducer is composed of an acoustic lens, impedance matching layers, piezoelectric materials, and backing layers. When an input voltage is applied to a piezoelectric material as an active material, it generates sound waves while vibrating. At that time, an impedance matching layer helps the sound waves to propagate forward while reducing the impedance mismatch that may occur at the interface between the active material and its front material. The impedance mismatch has a negative effect on the signal of an ultrasound transducer; thus, it is important to design a matching layer to overcome the issue. In this study, an optimized feature of a matching layer with gradient properties is studied. An objective function is defined to minimize both the average and the deviation of the reflection coefficients that are functions of the frequencies. As a result, an improvement in the signal characteristics with respect to the sensitivity and bandwidth is reported.

• Advances in materials Research
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• v.12 no.4
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• pp.309-330
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• 2023

The humid thermal vibration characteristics of a nonhomogeneous thermopiezoelectric nonlocal plate of polygonal shape are addressed in the purview of generalized nonlocal thermoelasticity. The plate is initially stressed, and the three-dimensional linear elasticity equations are taken to form motion equations. The problem is solved using the Fourier expansion collocation method along the irregular boundary conditions. The numerical results of physical variables have been discussed for the triangle, square, pentagon, and hexagon shapes of the plates and are given as dispersion curves. The amplitude of non-dimensional frequencies is tabulated for the longitudinal and flexural symmetric modes of the thermopiezoelectric plate via moisture and thermal constants. Also, a comparison of numerical results is made with existing literature, and good agreement is reached.