• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1518-1520
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• 2002

Purpose of this research compares best transfer speed about applied frequency and voltage using characteristic of $L_1-B_4$ mode and $L_1-B_8$ mode linear ultrasonic motor that use piezoelectric effect. By method of study, analyzed best transfer speed measuring and comparison load status that use actuality telephone card in $L_1-B_4$ mode linear ultrasonic motor and no-load status of $L_1-B_8$ mode linear ultrasonic motor. Experiment result is applied frequency(58.4Hz) in $L_1-B_4$ mode linear ultrasonic motor (load state) and the best transfer speed by 19.8[cm/s] at applied voltage(56V) point. Also, $L_1-B_8$ mode linear ultrasonic motor (no-load state) is best transfer speed by applied frequency(27.9kHz) and 32.96[cm/s] at applied voltage (50V) point.

• Journal of the Korean institute of surface engineering
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• v.44 no.6
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• pp.277-283
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• 2011

In this study, the cavitation test and electrochemical experiments were conducted for ALBC3(Cu-Al) alloy that has an excellent corrosion resistance and cavitation characteristic in sea water. Based on the ASTMG32 regulation, the cavitation test was performed with the cavitation and cavitation erosion tester using piezoelectric effect. The electrochemical characteristics are evaluated with potentiostatic experiments in activation polarization potential range. As a result, cavitation damage is increased proportionally to temperature and time at $30{\mu}m$ amplitude. It is appeared that acceleration period in weight loss presented over 6 hours under the cavitation environment in sea water. In addition, corrosion damages were observed at the potential range of -3.2~-1.4 V as the result of potensiostatic experiments during 12 hours in activation polarization potential range.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.477-477
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• 2011

In this paper, we synthesize ZnO wire on Si substrate by catalyst-free thermal chemical vapor deposition (CVD). Each ZnO wire is grew up at different condition such as temperature and O2 flow rate. The Young's modulus of individual ZnO wires were estimated using quasi-static and dynamic measurements, as well as resonance frequency measurements. Using this system, current-voltage characteristics of each ZnO wire structure fabricated on a trench were measured. A new concept of electromechanical device structure combined with the piezoelectric effect of ZnO will be suggested in the end of this paper.

• The Korean Journal of Ceramics
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• v.7 no.1
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• pp.30-35
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• 2001

The contribution of the non-$180^{\circ}C$ domains to the electric-field-induced strains (EFI-strains) of PZT ceramics was evaluated by an XRD method and by an interferometric method. The XRD intensity ratio of 200 and 002 diffraction peaks of tetragonal PZT was measured under strong electric fields. The amount of the $90^{\circ}$ domain reorientation was evaluated and the strain due to the domain reorientation was calculated. It was confirmed that the EFI-strain of PZT ceramics was equal to the sum of the strain calculated from the d$_33$ constant determined by the resonance-antiresonance method and the strain due to the $90^{\circ}$ domain reorientation. The amount of the $90^{\circ}$domain reorientation has a linear relation with the c/a ratio in the "soft" PZT ceramics. A Mech-Zehnder interferometer was constructed to measure the EFI-strains vs. electric-field curves of PZT ceramics as a function of frequency. The EFI-strain vs. electric-field curve showed a hysteresis due to the effect of the non-$180^{\circ}$ domain reorientation when the applied voltage was high and its frequency was low. The apparent piezoelectric constant increased from the d$_33$ value determined by the resonance-antiresonance method with decreasing frequency. This deviation was attributed to the non-$180^{\circ}$ domain contribution.tribution.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1037-1043
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• 1994

The effects of annealing atmosphere and temperature on piezoelectricity (k33) and the mechanical strength of machined PZT was studied. Morphotropic Nb-doped PZT was sintered, machined to a rod and then annealed between 80$0^{\circ}C$ and 100$0^{\circ}C$ in air, PbZrO3, and CuO atmospheres respectively. In air or PbZrO3 atmosphere, the compressive strength of Nb-doped PZT increased by 12% with little change in k33 irrespective of annealing temperature. In CuO atmosphere, on the other hand, the compressive strength increased by 20% with little change in k33 at 80$0^{\circ}C$ but both turned to significant decrease above 90$0^{\circ}C$. The examination of the phase distribution and microstructure beneath the surface of CuO-treated PZT revealed that the changes in compressive strength and k33 are closely related to the reaction between PZT and vaporized CuO:liquid PbO precipitated in shallow surface region by the substitution of Cu to Pb sites enhances the decrease in microcracks and the surface roughness at 80$0^{\circ}C$ ; rapid evaporation of precipitated PbO expands a porous region of changed composition into the bulk above 90$0^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1048-1053
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• 2002

In this paper, thin film bulk acoustic resonator(TFBAR) lattice and balanced type filter topologies are designed and fabricated. Aluminium nitride and platinum are used for piezoelectric material and top and bottom electrodes, respectively. Air-gap is placed to avoid silicon substrate loading effect and the performance of these lattice and balanced filters is compared with ladder filters. These filters have selectivity over 15 dB for lattice type and 30 dB for balanced type and reveal wider bandwidth of the ladder filters. For balanced type filters, minor tuning procedure is not needed and they are readily available for RF filter in wireless applications.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.25-32
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• 2004

We have carried out laboratory measurements of P-wave velocity and deformation strain during $CO_2$ injection into a porous sandstone sample, in dry and water-saturated conditions. The rock sample was cylindrical, with the axis normal to the bedding plane, and fluid injection was performed from one end. Using a piezoelectric transducer array system, we mapped fluid movement during injection of distilled water into dry sandstone, and of gaseous, liquid, and supercritical $CO_2$ into a water-saturated sample. The velocity changes caused by water injection ranged from $5.61\;to\;7.52\%$. The velocity changes caused by $CO_2$ injection are typically about $-6\%$, and about $-10\%$ for injection of supercritical $CO_2$, Such changes in velocity show that the seismic method may be useful in mapping $CO_2$ movement in the subsurface. Strain normal to the bedding plane was greater than strain parallel to the bedding plane during $CO_2$ injection; injection of supercritical $CO_2$ showed a particularly strong effect. Strain changes suggest the possibility of monitoring rock mass deformation by using borehole tiltmeters at geological sequestration sites. We also found differences associated with $CO_2$ phases in velocity and strain changes during injection.

• Transactions of Materials Processing
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• v.23 no.7
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• pp.413-418
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• 2014

The current study presents experimental and numerical results on the effect of ultrasonic vibrations on a cylindrical cup drawing of a cold rolled steel sheet(SPCC). An experimental apparatus, which can superimpose high frequency oscillations during deep drawing, was constructed by installing on the tooling ultrasonic vibration generators consisting of a piezoelectric transducer and a resonator. Conventional and vibration-assisted cylindrical deep drawing tests were conducted for various drawing ratios, and the limiting drawing ratios(LDR) for both methods were compared. To evaluate quantitatively the contribution from the ultrasonic vibrations to the reduction of friction between tools and material finite element analyses were conducted. Through a series of parametric analyses, the friction coefficients, which minimized the differences of punch load data between the experiments and simulations, were determined. The results show that the application of ultrasonic vibration effectively improves the LDR by reducing the friction between the tools and the material.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.849-855
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• 2012

Plant growth-promoting rhizobacteria (PGPR) pseudomonads have a large number of lipopolysaccharides on the cell surface, which induces immune responses. Cd-resistant PGPR prevalent at the Cd-affected sites under biophytostabilization was monitored. Transmissiom electron microscopy was used to the study the behavior of tolerance of PGPR to cadmium level and its effect on pseudomonad strains (Z9, S2, KNP2, CRPF, and NBRI). An immunosensor was developed by immobilizing antibody (anti-Z9 or anti-S2) against selected PGPR on a piezoelectric quartz crystal microbalance (QCM). Immunosensors were found to supplement the inherent specificity of antigen-antibody reactions with the high sensitivity of a physical transducer. On comparison of the efficiency of detection with ELISA, the spectrophotometric technique, the developed immunosensor was found to be more sensitive, fast, and reliable even after regeneration for several times. Thus, the immunosensor may be used for future detection of PGPR strains after automation of the screening process.

• Journal of the Korean Ceramic Society
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• v.17 no.2
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• pp.80-88
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• 1980

The sintering phenomena and piezoelectric properties of PZT ceramics of composition $Pb(Zr_{0.54} Ti_{0.46})O_3$ were investigated when a small quantity of $La_2O_3$ , $LaMnO_3$, $LaCrO_3$ were added. The unwanted chemical composition change in PZT during sinterin porces du to PbO evaporation poses a severe problem in PZt manufacturinig. It is observed tat an addition of small amount of $LaMnO_3$ to PZT markedly decreases the evaporation of PbO during sintering . The green compact of (1-x) PZT.xLaMnO3(x=0.02~0.10) could be sintered of under O2 atmosphere alone with no significant loss of PbO. The planar coupling factor kp of the sintered $0.98Pb(Zr_{0.54} Ti_{0.46})O_{3.0.02}LaMnO}3$ is similar to that of commercial PZT 6A. Microstructure investigation shows that part of sintering process of $Pb(Zr, Ti)O_3$.$LaMnO_3$ system progresses via liquid phase sintering. It is believed that the evaporation of PbO in PZT sintering is restricted by the addition of $LaMnO_3$ due to the above phenomena. Furthermore the solid solution of $LaMnO_3$ in PZT causes diffuses phase transition.