• 한국재료학회지
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• 제5권2호
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• pp.178-183
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• 1995

본 연구에서는 상온에서 정방성 조성인 $Pb_{0.9888}Sr_{0.012}(Zr_{0.52}Ti_{0.48})O_{3}$계 세라믹스를 소결 후 직류전계 및 코로나를 이용하는 방법으로 소결시편을 분극한 후 분극방법에 따른 시편의 압전특성을 조사하였으며, 열화현상을 평가하기 위한 방법으로 시편의 내부응력의 차이를 조사하였다. 이 결과 코로나 분극방법은 직류분극에 비하여 $30^{\circ}C$정도 저온에서도 최대 Kp값을 얻을 수 있었으며 열화현상이 천천히 진행되었고 절연파괴가 발생하지 않는 등의 장점이 관찰되었다. 그러나 Kp값은 직류분극의 경우가 코로나 분극에 비하여 약 9~10%정도 높은 값을 나타내었다.

• Smart Structures and Systems
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• 제13권1호
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• pp.1-24
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• 2014

The present study deals with two dimensional electro-elastic analysis of a functionally graded piezoelectric (FGP) cylinder under internal pressure. Energy method and first order shear deformation theory (FSDT) are employed for this purpose. All mechanical and electrical properties except Poisson ratio are considered as a power function along the radial direction. The cylinder is subjected to uniform internal pressure. By supposing two dimensional displacement and electric potential fields along the radial and axial direction, the governing differential equations can be derived in terms of unknown electrical and mechanical functions. Homogeneous solution can be obtained by imposing the appropriate mechanical and electrical boundary conditions. This proposed solution has capability to solve the cylinder structure with arbitrary boundary conditions. The previous solutions have been proposed for the problem with simple boundary conditions (simply supported cylinder) by using the routine functions such as trigonometric functions. The axial distribution of the axial displacement, radial displacement and electric potential of the cylinder can be presented as the important results of this paper for various non homogeneous indexes. This paper evaluates the effect of a local support on the distribution of mechanical and electrical components. This investigation indicates that a support has important influence on the distribution of mechanical and electrical components rather than a cylinder with ignoring the effect of the supports. Obtained results using present method at regions that are adequate far from two ends of the cylinder can be compared with previous results (plane elasticity and one dimensional first order shear deformation theories).

• 한국음향학회지
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• 제18권2호
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• pp.18-24
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• 1999

본 논문에서는 일반적인 loudspeaker에 비해 지향성이 높고, 광대역 특성을 가지는 초음파 스피커를 개발하고자 하였다. 스피커의 최적 구조를 위해 스피커 소자에서 압전 세라믹과 금속진동판의 재질 및 크기, 그리고 스피커 소자의 지지방식과 외장 케이스를 설계하였다. 설계결과를 바탕으로 초음파 스피커를 제작하고, 그 성능을 분석하여 설계이론의 타당성을 검증하였다. 제작에서는 큰 음압을 구현하기 위하여 초음파 배열 스피커를 설계, 제작하여 성능을 분석하였다. 본 연구에서 수립되어진 초음파 스피커의 설계 및 제작기법은 향후, 좋은 지향성과 넓은 대역폭을 가지는 스피커 개발에 유용하게 활용될 수 있을 것이다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.253-269
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• 1999

The development of telecommunication and information technology requires to develop new piezoelectric materials with small size, low impedance, wide pass band width and high thermal stability of frequency. Langasite (La3Ga5SiO14) single crystal has been researched substitute of quartz and LiNbO3 for the applications of SAW filter, BAW filter and resonator. Its single crystal growth has been carried out by Czochralski Method. So, in order to get single crystal with higher quality, in this study, lnagasite (La3Ga5SiO14) single crystal was grown by using Floating Zone (FZ) method and characterized. For the growth of langasite single crystals, the langasite powder was synthesized at 135$0^{\circ}C$ for 5hrs and the feed rod was sintered at 135$0^{\circ}C$ for 5hrs. The growing rate was 1.5mm/h and the rotation speed was 15 rpm for an upper rotation and 13 rpm for a lower rotation. In order to prevent the evaporation of gallium oxide, Ar and O2 gas mixture was flowed. The growth direction was analyzed by Laue back-scattered analysis. The composition of grown crystal was analyzed suing XRD and WDS. The electrical properties of grown crystal at various frequencies and temperature were discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.220-221
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• 2008

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device. The made 31 type triple-morph cantilever was resulted from the conditions of 100k$\Omega$, 0.25g, 154Hz respectively. The thick film was prepared at the condition of $6.57V_{rms}$, and its power was $432.31{\mu}W$ and its thickness was $50{\mu}m$.

• 대한기계학회논문집A
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• 제27권12호
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• pp.2079-2084
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• 2003

In biological cell manipulation, manual thrust or penetration of an injection pipette into an embryo cell is currently performed by a skilled operator, relying on visual feedback information only. Accurately measuring cellular forces is a requirement for minimally invasive cell injections. Moreover, the cellular force sensing is essential in investigating the biophysical properties for cell injury and membrane modeling studies. This paper presents cellular force measurements for the force feedback-based biomanipulation. Cellular force measurement system using piezoelectric polymer sensor is implemented to measure the penetration force of a zebrafish egg cell. First, measurement system setup and calibration are described. Second, the force feedback-based biomanipulation is experimentally carried out. Experimental results show that it successfully supplies real-time cellular force feedback to the operator at tens of uN and thus plays a main role in improving the reliability of biological cell injection tasks.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.237-240
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• 2003

In biological cell manipulation, manual thrust or penetration of an injection pipette into an embryo cell is currently performed by a skilled operator, relying on visual feedback information only. Accurately measuring cellular forces is a requirement for minimally invasive cell injections. Moreover, the cellular farce sensing is essential in investigating the biophysical properties for cell injury and membrane modeling studies. This paper presents cellular force measurements for the force feedback-based biomanipulation. Cellular force measurement system using piezoelectric polymer sensor is implemented to measure the penetration force of a zebrafish egg cell. First, measurement system setup and calibration are described. Second, the force feedback-based biomanipulation is experimentally carried out. Experimental results show that it successfully supplies real-time cellular force feedback to the operator at several tens of uN and thus plays a main role in improving the reliability of biological cell injection tasks.

• 한국광학회지
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• 제15권3호
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• pp.214-221
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• 2004

색분산 보상에 사용되는 선형 첩 광섬유 격자의 제작에 있어서 Group Delay Ripple(GDR)을 줄이기 위한 apodization 기술에 대해 이론적으로 분석하고 실험적으로 규명하고자 한다. 첩격자의 제작에는 위상 마스크를 이용한 UV 빔 스캐닝 기법을 적용하였고, PZT(Piezoelectric transducer)를 이용하여 위상 마스크를 빔 스캐닝 중에 적절하게 흔들어줌으로써 apodization이 일어나도록 하였다. 이러한 모든 과정이 컴퓨터 제어로 이루어지기 때문에 다양한 apodization 프로파일을 적용할 수 있었다. Gaussian, Raised-cosine, Blackman, 그리고 Hyperbolic tangent 등의 프로파일을 적용하여 첩격자를 제작하였으며 실험 결과 0.05 nm 구간평균 peak-to-peak GDR이 20ps 이하로 감소하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.145-149
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• 2004

In this study, leed-free piezoelectric ceramics were investigated for pressure sensor applications as a function of the amount of $La_2O_3$ addition at BNKT system. With increasing amount of $La_2O_3$ addition, density and dielectric constant were increased up to 0.9wt% addition and decreased after 0.9wt% addition, electromechanical coupling factor$(k_p)$ and mechanical quality factor$(Q_m)$ showed the maximum values at 0.2wt% addition and decreased after 0.2wt% addition. The $k_p$, density, dielectric constant and $Q_m$ were showed the optimum values of 0.40, $5.71g/cm^3$, 768 and 118 at $La_2O_3$ 0.2wt% addition, respectively.

• Transactions on Electrical and Electronic Materials
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• 제18권1호
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• pp.1-6
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• 2017

A comparative study of microwave and conventional sintering of lead-free $Bi_{1/2}(Na_{0.82}K_{0.18})_{1/2}TiO_3-BaZrO_3-CuO$ ceramics is presented. It was found that microwave sintering (MWS) can be successfully applied to the fabrication of large strain Bi-perovskite with electric field-induced strains comparable to those obtained with conventional sintering (CFS). Although MWS resulted in smaller grained microstructures than CFS, the ferroelectric properties were stronger in MWS-derived specimens than in the CFS-derived ones. The piezoelectric strain constant $d_{33}{^*}$ of the CFS-derived specimens reached a maximum value of 372 pm/V after sintering at $1100^{\circ}C$, whereas that of MWS-derived specimens peaked at $950^{\circ}C$ with a $d_{33}{^*}$ value of 324 pm/V.