• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.75-80
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• 1995

In order to fabricate the piezoelectric thin film of the PZT-PNN ternary compound, the metal alkoxides were used as starting materials. The electrical and crystalline properties of the thin film were evaluated. The X- RD study shows that the crystallization of the film is optimized at $550^{\circ}C$ of sintering temperature. According to the D-E hysterisis curve, the coercive field is 28.8 kV /cm, and the remanent polariztion is $18.3\;{\mu}C/cm^{2}$. The break down voltages of the thin films are $76.0\;{\sim}\;27.0\;MV/m$. When the sintering temperature is raised, the break down voltage is lowered. As a result of measuring the C-V characteristic curve of the ternary compound piezoelectric thin film, the relative dielectric constants are 406 for the composition (50:40:10), 1084 for the composition (50:30:20), 723 for the composition (45:35:20) and 316 for the composition (40:40:20).

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.68-76
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• 2001

Sonar is the system that detects objects and finds their location in water by using the echo ranging technique. In order to have excellent performance in variable environment, acoustic characteristics of this system must be analyzed accurately. In this paper, based on the finite element analysis, modeling and analysis of acoustic characteristics of underwater acoustic sensors are preformed. Couplings between piezoelectric and elastic materials, and fluid and structure systems associated with the modeling of piezoelectric underwater acoustic sensors are formulated. In the finite element modeling of unbounded acoustic fluid, IWEE (Infinite Eave Envelop Element) is adopted to take into account the infinite domain. When an incidence wave excites the surface of Tonpilz underwater acoustic sensor, the scattered wave on the sensor is founded by satisfying the radiation condition at the artificial boundary approximately. Based on this scattering analysis, the electrical response of the underwater acoustic sensor under incidence, so called RVS (Receiving Voltage Signal) is founded accurately. This will devote to design Sonar systems accurately.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1621-1622
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• 2006

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristic s were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Also we observed the movement characteristics of PZT actuator with LDV(Laser Doppler Vibrometer) system, oscilloscope and dynamic signal analyzer. Missing nozzles caused by bubbles in chamber were monitored by their resonance frequency. Using the water based ink of viscosity of 4.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets up to 20kHz, 4.4m/s and above 8pL at the different applied driving waveforms.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.511-515
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• 2012

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 24 piezoelectric cantilevers and a vehicle load transfer mechanism. Applying a vehicle load transfer mechanism rather than directly installing energy harvesters under roads decreases the area of road construction and allows more energy harvesters to be installed on the side of the road. The power generation amount with respect to the vehicular velocity change was assessed by installing the vehicle load transfer mechanism and the energy harvester in the form of speed bumps and underground. The energy harvester installed in a speed bump form generated power of 7.61 mW at the vehicular velocity of 20 km/h. Also, power generation of the energy harvester installed in the underground form was 63.9 mW at the vehicular velocity of 28 km/h. Although the number of piezoelectric cantilevers was reduced by 1/3 to 24 in comparison to the previous research results with 72 piezoelectric cantilevers, similar power generation characteristic value was obtained within the vehicular velocity of 20 km/h by altering the vehicle load transfer mechanism and cantilever vibration method.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.278-286
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• 2022

In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.159-166
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• 2011

Green house gas emissions are increasing as development of the industrial economy of the international community. Many countries in the world are endeavoring to reduce green house gas emissions under severe climate change. In order to protect grobal warming, government is trying to reduce green gas emissions under "Low Carbon Green Growth Policy" and investing climiate-firendly industries such as renewable energy harvesting. Renewable energy has been rapidly developing as a result of investment for development technology of using natural energy such as solar, wind, tidal, etc. There are lots of waste energy in the road space. However, nobody is not interested in waste energy from the road space. This paper present a fundamentally experimental study of energy harvesting technique to use waste energy in the road. The waste energy in the road is covered a pressure and impact of vehicles on the road, the radiant heat from asphalt pavement, road noise and vibration etc. In this study, an energy harvesting device using piezoelectric element is proposed and various tests are conducted to investigate a characteristic of this device as function of impact loading based on piezoelectric effect behavior. This paper shows the energy harvesting results of the device using domestic piezoelectirc element as a function of impact load size and pavement types.

• Journal of Surface Science and 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 Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.2-4
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• 2010

Nowadays, application fields using piezoelectric ceramics are various. On this paper, Characteristics of thin-type ultrasonic motor generating elliptical displacements has been analyzed by FEM, and then the motor was fabricated. Structure of the motor consists of sixteen ceramic pieces attached elastic body upper and bottom. Principle of the motor is to apply alternative voltages which have 90 phase difference to attached ceramics, and then elliptical displacements is generated at four edges of clastic body. And then rotor is rotated by the elliptical displacements. In case of ceramic thickness 1.5[mm], characteristic of the highest speed was found at 79[kHz]. In case of ceramic thickness 2[mm], Characteristic of the highest speed was observed at 77.5 [kHz]. Consequently, speed and torque of USM were increased linearly with increasing in applied voltage.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2076-2081
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• 2004

Future exhaust gas limits for diesel-driven passenger cars will force the automotive industry to significantly improve the performance of engine. Since modern common-rail injection systems deliver more degrees of freedom referring to the injection process, again the optimization of the injection process could offer a possibility to meet the exhaust gas limits. This study describes the characteristic the pilot spray structure of piezo-driven injector for a passenger car common-rail system to be applicable multiple injection caused by fast response rather than solenoid-driven injector. The piezo-driven injector is prototype injector with same needle chamber of solenoid injector and the solenoid-driven one is commercial injector. The pilot spray characteristic such as spray tip penetration, spray speed, spray angle were obtained by spray images, which is measured by the Mie scattering method with optical system for high-speed temporal photography. It was found that piezo-driven injector effected electric change as important factor and showed faster response than solenoid-driven injector.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.309-314
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• 1988

In this study, the effect of the size of sintered body on resonant and filter characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 piezo-electric system were investigated. The attenuation characteristics of ring-dot type and ladder type filter were also investigated. As the size of sintered body was decreased, the resonant characteristic(Fr, Fa) and the center frequency(Fo) were increased. As the poling field was increased, the Kp and bandwidth were increased. The big difference between rign-dot type and ladder type was the sharpness of bandwidth, selectivity and the movement of center frequency.