Hyeonkyu Joo

Applications of Self Power Device Using Piezoelectric Triple-Morph Cantilever for Energy Harvesting

In this paper, piezoelectric triple-morph cantilever was manufactured using the PMN-PZT thick film for electric harvesting device. The electrical characteristics of the piezoelectric triple-morph cantilever were investigated under dynamic conditions. The experimental results that piezoelectric triple-morph cantilever with 25 mm length and 5 mm width was operated under force of 100 N. A power of 0.432 mW were generated at the resonance frequency 154 Hz across a 100 kΩ optimal resistance. In order to apply automobile engine, the self-power device was designed using piezoelectric triple-morph cantilever with circuit. The applied result of automobile engine, output voltage was 3.57 Vrms on the running automobile engine.

Sinterability and Piezoelectric Properties of PMNZT Ceramics with Copper Oxide

The sinterability and piezoelectric properties of the Pb(Mg0.15Nb0.3Zr0.2Ti0.35)O3 ceramics with CuO sintering aid were investigated. The samples were synthesized with the conventional sintering method. The x-ray diffraction patterns indicated that all the samples formed a single-phase perovskite structure. The CuO additions improved the sinterability of the Pb(Mg0.15Nb0.3Zr0.2Ti0.35)O3 ceramics and increased the density and grain size of the samples. Excellent piezoelectric and electromechanical responses of d33 = 657 pC/N and kP = 0.72 were obtained from the high-density samples with 0.2 wt% CuO that were sintered at 1000 °C for 4 h.

Variation of Piezoelectric Transformer Electrode by Oxidation in Piezoelectric Inverter with Driving Time

Multi layer piezoelectric transformer has an advantage of the high step-up ratio, high electromechanical coupling coefficient (Kp ) and high mechanical quality factor (Qm ). However, they are subject to the electrode-crack and the need for an increased sintering temperature make the electrodes costly. The electrode-crack correlates to electrode oxidation in multi layer piezoelectric transformers and it is attended with drop-off in efficiency. In this study, high-power Rosen-type piezoelectric transformer were manufactured, and then investigated about electrode oxidation according to lapse of time for 4 month. The basic composition of piezoelectric ceramics consists of ternary 0.01Pb(Ni1/3Nb2/3)O3-0.08Pb(Mn1/3Nb2/3)O3-0.91Pb(Zr0.505Ti0.495)O3.