• Coupled systems mechanics
• /
• v.12 no.4
• /
• pp.337-364
• /
• 2023

The Rayleigh wave propagation is considered in the structure of the functionally graded piezoelectric material (FGPM) layer over the elastic substrate. The elastic substrate loosely bonds the layer through a corrugated interface, whereas its upper boundary is also corrugated but stress-free. Additionally, the solutions for the FGPM layer and substrate are derived using the fundamental variable separable approach to convert the partial differential equation to an ordinary differential equation. The results with boundary conditions lead to dispersion relations for the electrically open and electrically short cases in the determinant form. The outcomes have been numerically analyzed using a specific model. The findings were presented in the form of graphs, which were created using Mathematica 7. Graphs are plotted for variations in wavenumber and phase velocity. The outcomes may help measure interface defects and design Surface Acoustic Wave (SAW) devices.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.3
• /
• pp.391-395
• /
• 2007

MgO enhanced $(Ba_{0.6}Sr_{0.4})$ $TiO_3$ thick films have been fabricated by a tape casting and firing method for tunable devices on the microwave frequency band. In order to improve ferroelectric properties, the composite thick films enhanced with MgO on BST have been asymmetrically annealed by a focused halogen beam method. Dielectric constants of composite thick films are changed from 1050 to 1300 at 100 kHz after 60 s and 150 s annealing by the focused halogen beam. Even though no prominent changes were previously observed from the thick films before and after annealing in terms of chemical composition and surface morphology, it is clear that the average particle size of the thick films calculated by Scherrer's formula were increased by annealing. Furthermore, a strong correlation between particle size and dielectric constant of the composite thick films has been observed; dielectric constant increases with increased particle size. This has been attributed to the increased volume of ferroelectric domain due to increased particle sizes. As a result, the tuning range was improved by halogen beam annealing.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.4
• /
• pp.640-645
• /
• 2010

This paper describes the power generating property of hydrothermally grown ZnO nanorods on a flexible polyethersulfone (PES) substrate. The piezoelectric currents generated by the ZnO nanorods were measured when bending the ZnO nanorod by using I-AFM, and the measured piezoelectric currents ranged from 60 to 100 pA. When the PtIr coated tip bends a ZnO nanorod, piezoelectrical asymmetric potential is created on the nanorod surface. The Schottky barrier at the ZnO-metal interface accumulates elecntrons and then release very quickly generating the currents when the tip moves from tensile to compressed part of ZnO nanorod. These ZnO nanorods were grown almost vertically with the length of 300-500 nm and the diameter of 30-60 nm on the Ag/Ti/PES substrate at $90^{\circ}C$ for 6 hours by hydrothermal method. The metal-semiconductor interface property was evaluated by using a HP 4145B Semiconductor Parameter Analyzer and the piezoelectric effect of the ZnO nanorods were evaluated by using an I-AFM. From the measured I-V characteristics, it was observed that ZnO-Ag and ZnO-Au metal-semiconductor interfaces showed an ohmic and a Schottky contact characteristics, respectively. ANSYS finite element simulation was performed in order to understand the power generation mechanism of the ZnO nanorods under applied external stress theoretically.

• Journal of Periodontal and Implant Science
• /
• v.31 no.3
• /
• pp.531-542
• /
• 2001

Periodontal debridement is most important procedure in periodontal treatment, because periodontal disease is the biofilm infection. The use of ultrasonic instrument has many clinical advantages compared to classical hand instrument. The introduction of newly developed ultrasonic scaler tips made the use of ultrasonic scaler popular. However the study of tooth substance removal according to the working parameters of ultrasonic scaler with newly developed tips is not sufficient. The purpose of this study is to evaluate the effects of working parameters of piezoelectric ultrasonic scaler with curette tip on casting gold removal. The working parameters was standardized by the sledge device which controls lateral force(0.5 N, 1.0 N, 2.0 N) and power setting was adjusted 2, 4, 8 in P mode and S mode and instrumentation time was 5 seconds. The defect depth and width were measured with profile meter and defect surface was examined by SME. The depth of defect was significantly large in S mode( $39.58{\pm}19.35{\mu}m$) compared to P mode( $8.37{\pm}6.98{\mu}m$). There was significant decrease of depth of defect between 1.0N($32.87{\pm}27.18{\mu}m$) and 2.0N( $14.86{\pm}15.04{\mu}m$). The area of defect was also significantly large in S mode($4482.42{\pm}3551.71{\mu}m^2$) compared to P mode( $922.06{\pm}960.32{\mu}m^2$). There was significant decrease of area of defect between 1.0N($3889.12{\pm}3936.00{\mu}m$) and 2.0N( $974.66{\pm}986.01{\mu}m$). The change of mode did not effect on the width of the defect. The change of power setting did not effect on the depth, width, and area of defect. In spite of limitation of this study it could be concluded that the use of piezoelectric ultrasonic scaler with curette tip on S mode could make significant tooth substance loss.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.6 no.1
• /
• pp.51-57
• /
• 1981

Carriers moving in a semiconductor can impart gain or loss to an acousic wave traveling through Piezo-electric materials. In this paper, surface a coustic wave amplifiers, which employ the interaction between carriers drifting in a semiconduct or film and electic fields accompanying a Rayleigh wave propagating on a Piezoelectric substrate, are described. The effect of various electromagnetic boundary condition on th propagation of surface waves in Piezoelectrics is considered. An expression for the dependence of surface wave velocity on electic boundary conditions is derived. Calculations show that, for properly prepared material, significant amplification is expected up to the microwave frequencies. At high frequencies, gain is reduced because electro diffusion smooths out the electron bucning necessary for amplification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.695-700
• /
• 1997

A direct boundary element method(DBEM) is developed for thin bodies whose surfaces are rigid or compliant. The Helmholtz integral equation and its normal derivative integral equation are adopted simultaneously to calculate the pressure on both sides of the thin body, instead of the jump values across it, to account for the different surface conditions of each side. Unlike the usual assumption, the normal velocity is assumed to be discontinuous across the thin body. In this approach, only the neutral surface of the thin body has to be discretized. The method is validated by comparison with analytic and/or numerical results for acoustic scattering and radiation from several surface conditions of the thin body; the surfaces are rigid when stationary or vibrating, and part of the interior surface is lined with a sound-absorbing material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.9
• /
• pp.798-807
• /
• 2002

ZnO thin films on Si wafer were deposited by RF magnetron reactive sputter with various RF power, chamber pressure, argon/oxygen gas ratios ana substrate temperatures. Crystallinities, surface morphologies, and electrical properties of the films were investigated by XRD, AFM, RBS, and electrometer(keithley 617). ZnO films showed a strong c-axis preferred orientation. Surface roughness and resistivity were changed by the argon/oxygen gas ratio. The minimum surface roughness of 12${\AA}$ and maximum resistivity of $10^8\Omega cm$ were achieved at Ar/O$O_2$=0/100.

• Korean Chemical Engineering Research
• /
• v.44 no.2
• /
• pp.166-171
• /
• 2006

In this study, in using a piezoelectric material of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ (PMN-PT), which has a high electromechanical coupling coefficient, we have tried to study about this material can be practically available as a new biosensor to detect protein by using surface acoustic wave (SAW). As the results, the filtering of the center frequency of the PMN-PT substrate is a superior result to that of the $LiTaO_3$ (LT) substrate, but the result was not completely satisfactory. Also this study attempts to develop a sensing method to detect mismatched DNA in order to diagnose cancer. We could directly immobilize the MutS to the NTA using the EDC solution. But, we immobilized MutS using nickel and it is judged that is more effective method to detect mismatched DNA.

• Mass Spectrometry Letters
• /
• v.2 no.3
• /
• pp.61-64
• /
• 2011

Matrix Assisted Laser Desorption/Ionization-Time-of-Flight mass spectrometry (MALDI-TOF-MS) is the most widely used MS technique for glycan analysis. However, the poor point-to-point and sample-to-sample reproducibility becomes a limit in glycan biomarker research. A prespotted MALDI plate which overcomes the large crystal formation of 2,5-dihydroxybenzoic acid (DHB) has been developed and applied for glycan analysis. A homogeneous matrix coated surface without a crystal structure was formed on a hydrophilic/ hydrophobic patterned surface using a piezoelectric device. The reproducible MALDI-TOF-MS data have been presented using MALDI imaging of beer glycan as well as serum glycan eluted from 10% and 20% ACN elution fractions. The glycan profile from the serum glycan by MALDI-TOF-MS with a DHB prespotted plate was highly conserved for 10 different spectra and the coefficient of variations of significant ion peaks of MALDI data varies from 3.59 to 19.95.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.6
• /
• pp.132-140
• /
• 1998

Recently, precision machining technology has been developed continuously in order to make high productivity and quality assurance of the precision parts of several industrial fields. Waviness may occur on the surface of the machined parts due to the table motion error and the dynamic cutting mechanism between the tool and the workpiece. The waviness may fall off the form accuracy of the precision machine parts. In the research, a micro cutting device with piezoelectric actuator has been developed to control precise depth of cut and compensate the waviness on the surface of the workpiece. Experiments have been carried out in the precision lathe. The characteristics of the surface profile and cause of the waviness profile have been analyzed and waviness profiles of some cause have been compared with those of experiments.