In this study, in order to develop coupled vibration mode piezoelectric devices for Acoustic Emission(abbreviated as AE) sensor application with outstanding displacement and piezoelectric properties have been simulatedby ATILA FEM program. And, From the results of ATILA simulation, the AE sensor specimen, obtained superiorelectromechanical coupling factor and displacement, when the size of specimen is 3.45 mmΦ×3.45 mm with ratio ofdiameter/thickness(Φ/T)= 1.0. Therefore, AE sensor was fabricated by (Na,K,Li)(Nb,Ta) O3(abbreviated as NKL-NT)system piezoelectric ceramics using coupled vibration mode. The piezoelectric properties of NKL-NT ceramics wasexhibited that piezoelectric constant(d33), piezoelectric voltage constant(g33) and electro mechanical coupling factor(kp)have the excellent values of 261[pC/N], 40.10[10-3Vm/N], and 0.44, respectively. The manufactured piezoelectric devicewith ratio of Φ/T= 1.0 indicated the optimum values of resonant frequency(fr)= 556.5[kHz], antiresonant frequency(fa)=631.1[kHz], and effective electromechanical coupling factor(keff)= 0.473. The maximum sensitivity of the coupledvibration mode AE sensor was 55[dB] at the resonant frequency of 75[kHz]. The results show that the coupledvibration mode piezoelectric device is a promising candidate for the application AE sensor piezoelectric device.

In this study, novel ultrasonic rotary motor of hexadecagon shape stator was proposed. Statorof the hexadecagon ultrasonic motor was composed of an elastic ring and ceramics. The elastic ring hadsixteen sides and sixteen angular points. Eight ceramics were attached on the outer surface of the eightsides of the ring. When rotor of cylindrical shaft was inserted inside of the ring stator, central lines of thesixteen sides of the stator hold the shaft by the slight pressures(frictions). This slight pressure was apreload of the motor and it could be controlled by radius and thickness of the ring. When two sinusoidalvoltages which have 90 degree phase difference were applied to each four ceramics, elliptical displacementsof inner surface of the ring were obtained. These elliptical displacements of the inner surface rotated theshaft rotor through the frictions. The proposed hexadecagon ultrasonic motor was designed and analyzedby using the finite element method (FEM), depending on materials of the elastic ring. Based on the FEMresults, one model of motor which showed maximum displacement at contact points was chosen andfabricated. And characteristics of the motor were compared with simulated results. When the motor wasfabricated with these results, EL20ET0.5CT0.5CW2 model showed 115[rpm] speed about input voltage of60[Vrms] at 65.6[kHz]. And the maximum torque of 6[gfcm] was obtained. From these results, thehexadecagon shaped ultrasonic motor can be used to actuator for optical device which needs detailedposition control. Also it can be used to medical and portable device by reducing size and weight.

A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to inner surfaces of the square frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltage were applied to the ceramics on vertical surfaces. To find a model that generates elliptical motion at outside of the stator, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10EH3ET0.5CL4 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.

In this study, thickness shear mode piezoelectric devices for AE sensor with excellent displacement and sensitivity characteristics were simulated using ATILA FEM program, and then fabricated. Displacement and electro mechanical coupling factors of the piezoelectric devices were investigated. The simulation results showed that excellent displacement and electromechanical coupling factor was obtained when the ratio of Length/Thickness was 1. The piezoelectric device of L/T=1 exhibited the optimum values of fr=150 kHz, displacement= 6.23×10(-8)[m], k15= 0.598. The results show that the thickness shear mode piezoelectric device is a promising candidate for the application of AE sensor piezoelectric device.