• Coupled systems mechanics
• /
• v.5 no.2
• /
• pp.191-201
• /
• 2016

Coupled structures are widely seen in civil and mechanical engineering. In coupled structures, monitoring the translational motion of its key components is of great importance. For instance, some coupled arms are equipped with a hydraulic piston to provide the stiffness along the piston axial direction. The piston moves back and forth and a distance sensing system is necessary to make sure that the piston is within its stroke limit. The measured motion data also give us insight into how the coupled structure works and provides information for the design optimization. This paper develops two distance sensing systems for coupled structures. The first system measures distance with ultrasonic sensor. It consists of an ultrasonic sensing module, an Arduino interface board and a control computer. The system is then further upgraded to a three-sensor version, which can measure three different sets of distance data at the same time. The three modules are synchronized by the Arduino interface board as well as the self-developed software. Each ultrasonic sensor transmits high frequency ultrasonic waves from its transmitting unit and evaluates the echo received back by the receiving unit. From the measured time interval between sending the signal and receiving the echo, the distance to an object is determined. The second distance sensing system consists of a wire draw encoder, a data collection board and the control computer. Wire draw encoder is an electromechanical device to monitor linear motion by converting a central shaft rotation into electronic pulses of the encoder. Encoder can measure displacement, velocity and acceleration simultaneously and send the measured data to the control computer via the data acquisition board. From experimental results, it is concluded that both the ultrasonic and the wire draw encoder systems can obtain the linear motion of structures in real-time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.194-194
• /
• 2008

Lead oxide based ceramics, represented by PZT, are the most widely used materials for piezoelectric actuators, sensors, and transducers due to their excellent piezoelectric properties. In particular, high-performance multilayered piezoelectric ceramics for advanced electronic components have drawn great attention. In order to develop piezoelectric ceramics capable of being sintered at low temperature for multilayer piezoelectric device applications, the effect of CuO additions on the microstructures and electromechanical properties of the 0.4Pb$(Mg_{1/3}Nb_{2/3})O_3-0.25PbZrO_3-0.35PbTiO_3$ ceramics was investigated. The samples with CuO addition were synthesized by ordinary sintering technique. X-ray diffractions indicated that all samples formed a single phase perovskite structure. The addition of CuO improved the sinterability of the samples and caused an increase in the density and grain size at low temperature. The optimum sintering temperature was lowered by CuO additions. Excellent piezoelectric and electromechanical responses, $d_{33}$ ~ 663 pC/N, $k_p$ ~ 0.72, were obtained for the samples of high density with 0.1 wt% CuO addition sintered at $1050^{\circ}C$ for 4 h in air. These results show that the piezoelectric properties of PMNZT ceramics can be improved by controlling the microstructure and this system is potentially a good candidate as multilayer piezoelectric device for a wide range of electro-mechanical transducer applications.

• International Journal of Control, Automation, and Systems
• /
• v.5 no.4
• /
• pp.429-435
• /
• 2007

A number of different alternative actuation methods have been under active development for some specific applications where the traditional electromechanical actuators are difficult to apply. Recently, many of these substitutes are trying to employ new smart materials like electroactive polymers. However most of the polymeric materials are flexible and vulnerable so that they normally can not sustain external forces. Although the materials have shown a good potential to be used for alternative actuation mechanisms, no tangible industrial application is yet presented because of the reason. A conceptual design for a rectilinear motion actuator using dielectric elastomer is presented in this article. The introduced design concept might enable to produce fairly controllable rectilinear motions for various applications and the presented prototype actuator system is fully packaged in a small unit and controlled by a standard communication interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.9
• /
• pp.766-770
• /
• 2007

In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, $0.07Pb(Mn_{1/3}Nb_{2/3})O_3-xPb(Ni_{1/3}Nb_{2/3})O_3-(0.93-x)Pb(Zr,Ti)O_3$ ceramics system were fabricated using $Li_2CO_3-Bi_2O_3-CuO$ sintering aids and the specimens were sintered at $930^{\circ}C$. Thereafter, their piezoelectric and dielectric characteristics were investigated according to the amount of PNN substitution. At 9 mol% PNN substitution, density, electromechanical coupling factor ($k_p$), dielectric constant, mechanical quality factor ($Q_m$) and piezoelectric constant ($d_{33}$) showed the optimum value of $7.86g/cm^3$, 0.60, 1640, 1323 and 387 pC/N, respectively. It is considered that these values are suitable for piezoelectric divece application such ad multilayer piezoelectric actuator and ultrasonic vibrator with pure Ag internal electrode.

• Journal of the Korean Ceramic Society
• /
• v.19 no.4
• /
• pp.293-299
• /
• 1982

The effects of $MnO_2$ and $Cr_2O_3$ on the Piezoelectrictric properties of Pb(Mg1/2W1/2)0.3 Ti0.4 Zr0.3O3 Ceramics. Electromechanical properties in the system in connection with the sintering temperature and the effects of $MnO_2$ and $Cr_2O_3$ addition. The dielectric constant of the ceramics decreased with the additions of $MnO_2$ while the additions of $Cr_2O_3$ increased the value. The Planar coupling factor (Kp) of the ceramics with 0.2wt% $MnO_2$ and with 0.2wt% $Cr_2O_3$ gave the highest value of 0.52 and 0.513 as sintered at 106$0^{\circ}C$, 108$0^{\circ}C$, respectively. The value of mechanical Q-factor were in parallel with the fired density of the ceramics. The optical micrography of the sintered bodies showed that the additions of $MnO_2$ promoted the grain growth, while the additions of $Cr_2O_3$ retarded the grain growth.

• The Korean Journal of Ceramics
• /
• v.1 no.1
• /
• pp.13-20
• /
• 1995

Effects of thermal annealing on the dielectric/piezoelectric properties of $Pb(Zn, Mg)_{1/3}Nb_{2/3}O_3-PbTiO_3$ ceramics (PZMNPT) with Zn/Mg=6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Both the relative dielectric permittivity ($\varepsilon$r)and the piezoelectric constant($d_33$)/electromechanical coupling constant ($k_p$)were increased by thermal annealing ($800^{\circ}$~$900^{\circ}C$) after sintering at $1150^{\circ}C$ for 1 hr. Based on the dielectric analysis using the series mixing model and the concept of a random distribution of the local Curie points, the observed improvements in the dielectric and piezoelectric properties of PZMN-PT were interpreted in terms of the elimination of PbO-rich amorphous intergranular layers(~1nm) induced by thermal annealing. A concrete evidence of the presence of amorphous grain-boundary layers in the unannealed (as-sintered) specimen was obtained by examining the structure of intergranular region using a TEM.

• Journal of the Korean Ceramic Society
• /
• v.40 no.4
• /
• pp.393-397
• /
• 2003

To investigate the effect of AIN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crybtallographically different AIN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ($\kappa$$\_$eff/)$^2$ in resonators increased gradually. The least 4 degree of full width at half maximum in an AIN(002) rocking curve, which corresponds to $\kappa$$^2$$\_$eff/ of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AIN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AIN film was extracted to be about 10200 n/s by mathematical analysis using Matlab.

• International Journal of Fluid Machinery and Systems
• /
• v.10 no.2
• /
• pp.176-188
• /
• 2017

The nozzle-flapper valves are widely applied as a pilot stage in aerospace and military system. A subject of the analysis presented in this work is to find out a reasonable range of null clearance between the nozzle and flapper. This paper has presented a numerical flow coefficient simulation. In every design point, a parameterized model is created for flow coefficient simulation and cavitation under different conditions with varying gap width and inlet pressure. Moreover, a new test device has been designed to measure the flow coefficient and for visualized cavitation. The numerical simulation and test results both indicate that cavitation intensity gets fierce initially and shrinks finally as the gap width varies from small to large. From the curve, the flow coefficient mostly has experienced three stages: linear throttle section, transition section and saturation section. The appropriate deflection of flapper is recommended to make the gap width drop into the linear throttle section. The flapper-nozzle null clearance is optionally recommended near the range of $D_N/16$. Finally through simulation it is also concluded that the inlet pressure plays a little role in the influence on the flow coefficient.

• Journal of Biomedical Engineering Research
• /
• v.14 no.1
• /
• pp.41-50
• /
• 1993

This paper proposes an adaptive technique for the cardiac output regulation of a pendulum type electromechanical TAH. This techinque, which consists of two RLSE's and two PASTC' 5, performs Its controllability over the TAIB so that the m(RAP) and m(LAP) values re- main close to their desired values under she assumption that the variation of m(RAP) and m (LAP) are dominated by the variation of C.0. and the difference between the left and right ventricular output, respectively. To evaluate the performance of the proposed control system, a simulation is performed by using a human model which contains physiologic, drug and treatment, artificial heart and noise models. As a result, dual adaptive controller showed that abnormal m(LAP) and m(RAP) could be recovered to the normal range within 10minute and maintained desired value in steady state. The operation of this controller prored to be robust in spite of the rapid variation of human status.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.689-692
• /
• 2001

In this paper, the pizoelectric and dielectric properties of 0.95Pb(ZrxTil-x)O$_3$- 0.05Pb(Mn$\_$0.2/Fe$\_$0.4/W$\_$0.4/)O$_3$piezoelectric ceramics is investigated as a function of Zr/Ti mole ratio. Also, MPB(Morphotropic Phase Boundary) and optimal sintering temperature is studied using XRD and SEM. As a results, when Zr/Ti mole ratio is 52/48, electromechanical coupling factor, k$\_$p/, is 58[%], permittivity, $\varepsilon$$\^$T/$\_$33//$\varepsilon$0, is 1360 and piezoelectric strain constant, d$\_$33/ is 265[pC/N] and the piezoelectric and dielectric properties become maximum. Phase transition temperature of its ternary piezoelectric system is about 350[$^{\circ}C$]. From the XRD analysis, when Zr/Ti mole ratio is 52/48, tetragonal phase transits to rhombohedral phase. Also, From measuring results of the sintering density, when sintering temperature is 1050[$^{\circ}C$], sintering density become maximum and is about 7930[kg/㎥], and average grain size is about 2-3[$\mu\textrm{m}$].