• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.213-219
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• 1999

Piezoelectric element is deformed by driving voltage pattern. We developed a device of moving LD(laser disk) to use the rapid deformation of piezoelectric element. If driving voltage is changed very rapidly, the difference of acceleration is accurred between spindle motor and LD. To move LD on turn table is attained by utilizing difference of acceleration. This paper describes theoretical and experimental results about the movement of LD and presents to measure the center of mass LD with unbalance force.

• 한국안전학회지
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• 제24권6호
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• pp.13-19
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• 2009

The thermoelectric cooling system consisted of the thermoelectric module, a heat sink and a cooling fan, respectively. Also, the piezoelectric actuator was applied to improve the performance of thermoelectric cooling system and investigate the heat transfer phenomenon. The temperature distribution of test section was measured to investigate cooling characteristics of thermoelectric cooling system. The flow phenomenon of test section was visualized using visualization device. When the piezoelectric actuator was applied to the heat transfer process of thermoelectric cooling system, acoustic streaming was occurred in test section. The acoustic streaming was occurred forced convection flow, and was regularly formed the temperature distribution in test section. The results clearly show that the acoustic streaming is one of the prime effects to enhance the convection heat transfer and can enhance the performance of thermoelectric cooling system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.711-714
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• 2000

In this study, the physical properties of the acoustic element and case with metal-piezoelectric ceramics were analyzed. The dielectric and piezoelectric properties of 0.5 wt% MnO$_2$and NiO doped 0.1Pb(Mg$\_$1/3Nb$\_$2/3)O$_3$-0.45PbTiO$_3$-0.45PbZrO$_3$ceramics were investigated aiming at acoustic transducer applications. The vibration characteristics for the laminated circular plate was analyzed for the various thickness and diameter of the piezoceramic layer and metal layer. Also, the acoustic characteristics for the geometrical form of case have been investigated. The design and fabrication method worked in this paper can be utilized in development of actuator and acoustic device.

• 대한전기학회논문지
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• 제41권6호
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• pp.687-693
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• 1992

To improve dielectric, piezoelectric and temperature stability in 0.50Pb(SnS11/2TSbS11/2T)OS13T - 0.35PbTiOS13T - 0.60PbZrOS13T + 0.4[wt%]MnOS12T piezoelectric ceramics which is used for surface acoustic wave devices, CrS12TOS13T was added and the specimens were fabricated by Hot Press method, and their characteristics were measured with CrS12TOS13T addition. From the results, in the specimen added by 0.2[wt%]CrS12TOS13T, dielectric constant and mechanical quality factor were 380 and 2307, respectively, and it was suited for surface acoustic wave device and the temperature coefficient of the resonant frequency in the specimen added by 0.4[wt%]CrS12TOS13T was the least value of 74.96[ppm/$^{\circ}C$].

• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.753-757
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• 2001

1-(2'2'3'-Tricyano-3-carbomethoxycyclopropyl)-34-di-(2'-hydroxyethoxy)benzene, (4) was prepared by the reaction of bromomalononitrile with methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3). Diol 4 was condensed with tolylene-2,4-diisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, and 1,6-hexamethylenediisocyanate to yield polyurethanes 5, 6, and 7 containing tricyanocyclopropane functionalities in the pendant group. The resulting polymers 5-7 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25-0.30 dL/g. Polyurethanes 5-7 showed a thermal stability up to 300 $^{\circ}C$ in TGA thermograms. Solution-cast films showed Tg values in the range of 100-125 $^{\circ}C$ and piezoelectric coeffcients (d31) of the poled polymer films were 1.3-2.0 pC/N, which are acceptable for piezoelectric device applications.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권3호
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• pp.156-156
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• 2000

The piezoelectric properties and the doping effect for $0.95Pb(Zr_xTi_{l-x})O_3+0.O5Pb(Mn_{1/3}Nb_{2/3})O_3$compositions were studied. Also, the heat generation and the change of electromechanical characteristics, the important problem in practical usage, were investigated under high electric field driving. As a experiment results under low electric field, the value of $k_p$ and ${\varepsilon}_{33}^T$ were maximized, but $Q_m$ was minimized $(k_p=0.57, Q_m=1550)$ in the composition of x=0.51. In order to increase the values of $Q_m$, $Nb_2O_5$ was used as a dopant. As the result of that, the grain size was suppressed and the uniformity of grain was improved. Also, the values of $k_p$ decreased, and the values of $Q_m$ increased with doping concentration of $Nb_2O_5$ . As a experiment results under high electric field driving, when vibration velocity was ower than 0.6[m/s], the temperature increase was 20[℃], and the change ratio of mechanical quality factor was less than 10[%]. So, its electromechanical characteristics was very stable. Conclusively, piezoelectric ceramic composition investigated at this paper is suitable for application to high power piezoelectric devices.

• Composites Research
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• 제27권4호
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• pp.141-145
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• 2014

본 논문은 충격 센서로써 압전 페인트 센서를 사용해 구조물 건전성 모니터링을 수행하였다. 본 연구에 적용된 압전 페인트는 페인트 형태의 압전 재료로 물체에 얇게 코팅할 수 있고, 추가적인 외부 전원 필요 없이 충격 센서로 사용할 수 있다는 장점을 지닌다. 본 논문에서는 복합재 시편에 압전 페인트 센서를 네 부분으로 구분하여 도포한 후 충격 실험을 수행하였다. 압전 페인트 센서의 감도는 충격 힘에 따른 출력 전압을 측정하여 구하였고, 감도 측정과 더불어, 시편에 충격이 가해진 경우 압전 페인트 센서의 출력 신호를 비교하여 충격 위치도 추정하였다.

• 한국전기전자재료학회논문지
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• 제29권11호
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• pp.712-715
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• 2016

In this paper, we fabricated flexible CNT/PVDF piezoelectric composite device by introducing CNTs (carbon nanotubes) into PVDF (poly-vinylidene fluoride) solution using spray coating technique. Flexible PEDOT:PSS conducting polymer was used as electrodes. We tried to improve the piezoelectric performance from the CNT/PVDF composite film by increasing the portion of the ${\beta}$-phase PVDF in the film. We confirmed the structural conformation of the CNT/PVDF composite film as a function of CNT concentration by using FT-IR (fourier transform infra-red). As increasing CNT concentration, portion of the ${\beta}$-phase PVDF and resulting piezoelectric performance increased in the CNT/PVDF composite film. We found that CNTs introduced were played as seeds for formation of the ${\beta}$-phase PVDF in the CNT/PVDF composite film and resulting improvement of the piezoelectric performance.

• 한국재료학회지
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• 제31권1호
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• pp.43-53
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• 2021

Dynamic behavior of piezoelectric ZnO nanowires is investigated using finite element analyses (FEA) on FE models constructed based on previous experimental observations in which nanowires having aspect ratios of 1:2. 1:31, and 1:57 are obtained during a hydrothermal process. Modal analyses predict that nanowires will vibrate in lateral bending, uniaxial elongation/contraction, and twisting (torsion), respectively, for the three ratios. The natural frequency for each vibration mode varies depending on the aspect ratio, while the frequencies are in a range of 7.233 MHz to 3.393 GHz. Subsequent transient response analysis predicts that the nanowires will behave quasi-statically within the load frequency range below 10 MHz, implying that the ZnO nanowires have application potentials as structural members of electromechanical systems including nano piezoelectric generators and piezoelectric dynamic strain sensors. When an electric pulse signal is simulated, it is predicted that the nanowires will deform in accordance with the electric signal. Once the electric signal is removed, the nanowires exhibit a specific resonance-like vibration, with the frequency synchronized to the signal frequency. These predictions indicate that the nanowires have additional application potential as piezoelectric actuators and resonators.

• 한국전기전자재료학회논문지
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• 제36권5호
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• pp.525-530
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• 2023

Stretchable piezoelectric energy harvester (S-PEHs) based on composite materials are considered one of the potential candidates for realizing wearable self-powered devices for smart clothing and electronic skin. However, low energy conversion performance and expensive stretchable electrodes are major bottlenecks hindering the development and application of S-PEHs. Here, we fabricated the S-PEH by adopting the piezoelectric composites with enhanced stress transfer properties and kirigami-patterned textile electrodes. The optimum contents of piezoelectric BaTiO₃ nanoparticles inside the carbon nanotube/ecoflex composite were selected as 30 wt% considering the trade-off between stretchability and energy harvesting performance of the device. The final S-PEH shows an output voltage and mechanical stability of ~5 V and ~3,000 cycles under repeated 150% of tensile strain, respectively. This work presents a cost-effective and scalable way to fabricate stretchable piezoelectric devices for self-powered wearable electronic systems.