• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.48-55
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• 1995

A surface acoustic wave (SAW) sensor for the detection of odorants has been constructed by depositing various phospholipids and fatty acids onto the surface of the SAW device. The characteristics of a SAW device operating at 310 MHz deposited with silicon monoxide were analyzed. Menthone, amylacetate, acetoin, and other organic gases show different affinities to the coated lipids. An explanation is given for different odorant affinities based on the monolayer properties of phospholipids. The identification of odorants depending on the tkpe of lipid used for coating is discussed in terms of the similarity of their normalized resonant frequency shift patterns. Using a number of different lipid-coated SAW devices, odorants can be identified by a computerized pattern recognition algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1427-1429
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• 1997

In this study, piezoelectric transducer were designed and manufactured using PZT-5A which have relatively high electromechanical coefficient. A epoxy is a good material as matching and backing layers. The envelope was reduced 60% as using matching layer and 76% as using matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error and resolution of PZT-5A probe were improved as increasing frequency. Envelope was effectively reduced by backing layer but sensitiveness was poor.

• E2M - 전기 전자와 첨단 소재
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• 제1권2호
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• pp.162-167
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• 1988

본 논문에서는 Pb(Sn$_{1}$7/Mn$_{2}$7/Nb$_{4}$7/)O$_{3}$- Pb(Zr, Ti)O$_{3}$계에 La$_{2}$O$_{3}$를 첨가하여 그양에 따른 압전일 전기력 성질의 변화를 고찰하였다. La$_{2}$O$_{3}$ 첨가량의 증가에 따라 유전상수, 압전 d상수, 유전손실, 비저항 등은 증가하였으나 경시 변화량은 오히려 감소하였다.

• E2M - 전기 전자와 첨단 소재
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• 제5권2호
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• pp.207-215
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• 1992

본 연구에서 xPb(A $l_{0.5}$N $b_{0.5}$) $O_{3}$-(1-x)Pb(Z $r_{0.52}$ $Ti_{o.48}$) $O_{3}$계의 조성변화에 따른 유전 및 압전특성에 관해 실험한 결과 다음과 같은 결론을 얻었다. PAN의 첨가량이 증가함에 따라 c축은 수축되고 a축은 팽창하여 tetragonality는 감소하였고 grain의 크기와 Curie온도 또한 PAN의 첨가량에 따라 감소하였으나 밀도와 유전상수는 PAN의 양이 5mol%까지 증가하다가 그 이상에서는 감소하는 경향을 보였다. PAN의 첨가량이 증가함에 따라 시편의 비저항은 증가하였고 Kp는 PAN의 양이 5mol%첨가시 60%로 최대치를 보였으나 Qm은 최소치를 나타내었다.다.

• E2M - 전기 전자와 첨단 소재
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• 제6권3호
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• pp.207-213
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• 1993

Pb(Z $r_{0.54}$, $Ti_{0.46}$) $O_{3}$에 B $i_{2}$ $O_{3}$를 0.0wt%까지 첨가하여 미세구조, 유전, 압전, 성질에 미치는 영향을 고찰하였다. B $i_{2}$ $O_{3}$의 고용범위는 약 0.5~0.7wt%정도 이었고 B $i_{2}$ $O_{3}$ 첨가량이 증가함에 따라서 결정립의 크기가 감소하였다. B $i_{2}$ $O_{3}$첨가량이 증가함에 따라 고용한계까지는 $d_{33}$ , tan .delta., .xi.$_{r}$(분극후)값이 증가하였으며 Qm값과 밀도는 감소하였다. $K_{p}$ 값은 B $i^{3+}$ 가 P $b^{2+}$를 치환하므로 형성되는 Pb공공의 형성에 의해 자발분극이 증가됨에 따라 증가하였다.다.

• Journal of Korean Vacuum Science & Technology
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• 제3권2호
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• pp.126-129
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• 1999

PbTio3 is a promising material with perovskite structure for pyroelectric sensor applications with its superior pyroelectric properties, low dielectric constants, and low piezoelectric constants. Growth of pyroelectric thin films in general, needs relatively higher temperatures than those of conventional Si semiconductor processing However, low growth temperature is advantageous for the device integration. We report the low temperature (350$^{\circ}C$) growth of PbTio3 thin films by 3-gun DC magnetron reactive sputtering. The effects of substrate temperature, Pb-flux, and total pressure on crystalinity and preferred orientation of PbTio3 thin films are reported.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.433-433
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• 2009

ZnO-based materials have been extensively studied for optoelectronic applications due to their superiors physical properties such as wide direct bandgap (~3.37 eV), large exciton binding energy (~60 meV), high transparency in the visible region, and low cost. Especially, one-dimensional (1D) ZnO nanostructures have attracted considerable attention owing to quantum confinement effect and high crystalline quality. Additionally, various nanostructures of ZnO such as nanorods, nanowires, nanoflower, and nanotubes have stimulated the interests because of their semiconducting. and piezoelectric properties. Among them, vertically aligned ZnO nanorods can bring the improved performance in various promising photoelectric fields including piezo-nanogenerators, UV lasers, dye sensitized solar cells, and photo-catalysis. In this work, we studied the effect of the annealing temperature of homo seed layers on the formation of ZnO nanorods grown by hydrothermal method. The effect of annealing temperature of seed layer on the length and orientation of the nanorods was investigated scanning electron microscopy investigation. Transmission electron microscopy and X-ray diffraction measurement were performed to understand the effect of annealing temperatures of seed layers on the formation of nanorods. Moreover, the optical properties of the seed layers and the nanorods were studied by room temperature photoluminescence.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.621-625
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• 2020

Cast austenitic stainless steel (CASS) is used for fabricating different components of the primary reactor coolant system of pressurized water reactors. However, the thermal embrittlement of CASS resulting from long-term operation causes structural safety problems. Ultrasonic testing for flaw detection has been used to assess the thermal embrittlement of CASS; however, the high scattering and attenuation of the ultrasonic wave propagating through CASS make it difficult to accurately quantify the flaw size. In this paper, we present a different approach for evaluating the thermal embrittlement of CASS by assessing changes in the material properties of CASS using a nonlinear ultrasonic technique, which is a potential nondestructive method. For the evaluation, we prepared CF8M specimens that were thermally aged under four different heating conditions. Nonlinear ultrasonic measurements were performed using a contact piezoelectric method to obtain the relative ultrasonic nonlinearity parameter, and a mini-sized tensile test was performed to investigate the correlation of the parameter with material properties. Experimental results showed that the ultrasonic nonlinearity parameter had a correlation with tensile properties such as the tensile strength and elongation. Consequently, we could confirm the applicability of the nonlinear ultrasonic technique to the evaluation of the thermal embrittlement of CASS.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.208-208
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• 2010

Zinc oxide (ZnO) is a functional material with interesting optical and electrical properties, a wide band gap (more than 3.3 eV), a high transmittance in the visible light region, piezoelectric properties, and a high n-type conductivity. This material has been investigated for use in many applications, such as transparent electrodes, blue light-emitting diodes, and ultra-violet detector. ZnO films grown under low oxygen pressure by thin film deposition methods show low resistivity and large free electron concentration. Therefore, reducing the background carrier concentration in ZnO films is one of the major challenges ahead of realizing high-performance ZnO-based optoelectronic devices. In this study, we deposited ZnO thin films on sapphire substrates by pulsed laser deposition (PLD) with employing an oxygen plasma source to decrease the background free-electron concentration and enhance the crystalline quality. Then, the substrate temperature was varied between 200 'C to 900 'C The vacuum chamber was initially evacuated to a pressure of $10^{-6}$ Torr, and then a pure $O_2$ gas was introduced into the chamber and the pressure during deposition was maintained at $10^{-2}$ Torr. Crystallinity and orientation of ZnO films were investigated by X-ray diffraction (XRD). The film surface was analyzed with atomic force microscope (AFM). And electrical properties were measured at room temperature by Hall measurement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.657-661
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• 2002

PZT powder was prepared by partial oxalate method using $(Zr_{0.53}Ti_{0.47})O_2$, $Pb(NO_3)_2$ and $(COOH)_2{\cdot}2H_2O$ as a precipitant. $Nb_2O_5$ additive effect on microstructure and piezoelectric properties of PZT ceramics were investigated. The coexistence of rhombohedral and tetragonal phases of PZT ceramics at the sintering temperature of $1100^{\circ}C$ was revealed from the X-ray diffraction patterns. The grain size PZT ceramics was decreased with the increase $Nb^{5+}$. and the sinterbility of PZT ceramics was decreased with the increase $Nb^{5+}$ addition. The electromechanical coupling factors $K_p$ show above 0.60 at $1100^{\circ}C$ sintering temperature by $Nb_2O_5$ addition above 0.6mol%.