• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.223-224
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• 2006

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. This transformer has multi-layered structure. The piezoelectric transformers operated m each transformer's resonance vibration mode. The electrodes and poling directions on commercialy available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor ($k_p,\;k_{15}$) becomes effective rather than the transverse mode coupling factor ($k_{31}$). The Resonance frequency is 65.22[kHz] and maximum voltage step-up ratio is 149. Multi-layered transformer has better efficiency and step-up ratio than the single-layered transformer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.367-370
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• 2004

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p,\;k_{15})$ becomes effective rather than the transverse meed coupling factor $(k_{31})$. A single layer prototype transformer, 26[m] in diameter and 2.0[mm] thickness, was fabricated, such as step-up ratio, power transformation efficiency and temperature were measured.

• Transactions on Electrical and Electronic Materials
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• 제1권3호
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• pp.1-5
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• 2000

This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulation power supplies. This piezoelectric transformer operate in the second thickness resonant vibration mode. Accordingly its resonant frequency is higher than 1 NHz, Because output power is low if input and output part of transformer are consisted of single layer, this research suggests a new method, which is consisted of both input and output part of transformer have 2-layered piezoelectric ceramics, The size of transformer is 20 mm in width and length, and 1.4 mm in thickness, respectively, To design a high efficient switching circuit of the transformer, internal circuit parameters were measured and then weve calculated a parameter of inductor nd capacitor to design a driving circuit, Weve used a MISFET and its driver circuit modified a calp oscillator circuit as the primary switching circuit.

• 비파괴검사학회지
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• 제24권5호
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• pp.476-486
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• 2004

본 논문은 두 편으로 구성된 스마트능동레이어 (smart active layer, SAL) 센서 개발에 관한 두 번째 것이다. 이미 첫 번째 논문에서 언급되었지만, 구조물 건전성 감시 (structural health monitoring, SHM)는 구조물 안전 감시의 비용과 편리성을 개선하기 위한 방법으로서, 산업현장에서 그 응용이 점차 증가하는 새로운 기술이며, 최근 실제 응용을 하기 위한 스마트 센서의 개발 및 연구가 매우 활발하다. 본 논문에서는 첫 번째 논문에 기술된 SAL 센서의 이론 및 개념 연구에 이어서 실제 제작 및 적용연구에 관해 기술한다. 본 연구에서는 탄성파 감지를 위한 스마트 압전 센서 SAL을 개발하였는데, 압전 소자, 전자기파 차폐층 (EMI shielding lave.) 및 보호 층(protection layer)으로 구성되었다. 보호층에 일정 간격으로 분포된 압전 센서가 부착되고, 이들을 전기적으로 연결하는 회로층이 위치하고 있다. 모두 4종류의 SAL 센서가 설계, 제작 및 시험되었으며 이에 대해 상세히 기술하고 있다. 본 연구를 통해 SAL 센서는 SHM의 수행과 탄성파에 의한 손상 위치를 표정하는데 적용 가능할 것으로 예상된다.

• 한국음향학회지
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• 제33권2호
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• pp.102-110
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• 2014

양 전극 사이에 압전층 외에 비압전성의 접합층이 존재하는 ${\lambda}/4$ 모드 PVDF 초음파 트랜스듀서에 있어서 그 접합층이 트랜스듀서의 성능에 미치는 영향을 등가회로에 의해 해석하였다. 등가회로로서는 Kikuchi 등이 제안한 전송선로 모델[Sound of IEICE, 55-A, 331-338 (1981)]을 도입하였는데, 먼저 그 모델에 의한 해석의 타당성을 $80{\mu}m$ 두께의 PVDF 압전막이 동(Cu) 후면체에 부착되는 세 가지 경우를 가정한 KLM 모델과의 비교를 통해 검증하였다. 다음으로, 그 압전막과 더불어 $5{\mu}m{\sim}20{\mu}m$ 두께의 에폭시 접합층을 갖는 다섯 개의 트랜스듀서를 제작하여 펄스 에코 응답을 측정한 후 시뮬레이션 결과와 비교하였다. 두 결과는 서로 잘 일치하였는바, 도입한 Kikuchi 모델에 의해 접합층이 트랜스듀서의 성능에 미치는 영향을 파악할 수 있음을 알았는데, 접합층이 $20{\mu}m$일 때는 그 접합층이 없을 때에 비해 중심주파수와 대역폭은 각각 약 19.7 %, 25.0 % 감소하고, 삽입손실은 57.2 % 증가하는 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.327-327
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• 2010

In this paper, an investigation of factors affecting piezoelectric transformers is presented by ATILA software. These transformers are multi-layer piezoelectric transformers in square shape $28\;{\times}\;28\;mm$ and operate in first vibration mode for step-down function. The piezoelectric transformers were modeled in 3D-dimension and analyzed using finite element method in ATILA software, a popular software in piezoelectric analysis. Modal and harmonic modules were used in this process. Effective factors to the properties of piezoelectric transformers including different input electrode patterns, directions of polarization, sizes of connective comer, number of layers were examined on the simulated model using input voltage of 20 V and load resistance of $100\;{\Omega}$. Moreover, thermal analysis was also obtained with conditions of input voltage of 5 V and no-load.

• Smart Structures and Systems
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• 제13권4호
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• pp.547-565
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• 2014

This paper investigates the design of a perfect point load actuator based on flat triangular piezoelectric patches. Applying a difference of electric potential between the electrodes of a triangular patch leads to point loads at the tips and distributed moments along the edges of the electrodes. The previously derived analytical expressions of these forces show that they depend on two factors: the width over height (b/l) ratio of the triangle, and the ratio of the in-plane piezoelectric properties ($e_{31}/e_{32}$) of the active layer of the piezoelectric patch. In this paper, it is shown that by a proper choice of b/l and of the piezoelectric properties, the moments can be cancelled, so that if one side of the triangle is clamped, a perfect point load actuation can be achieved. This requires $e_{31}/e_{32}$ to be negative, which imposes the use of interdigitated electrodes instead of continuous ones. The design of two transducers with interdigitated electrodes for perfect point load actuation on a clamped plate is verified with finite element calculations. The first design is based on a full piezoelectric ceramic patch and shows superior actuation performance than the second design based on a piezocomposite patch with a volume fraction of fibres of 86%. The results show that both designs lead to perfect point load actuation while the use of an isotropic PZT patch with continuous electrodes gives significantly different results.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.33-38
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• 2000

In this study, multilayer piezoelectric actuators were fabricated with 75 layers by a conventional multi-layer capacitor (MLC) techniques, using 70Ag/30Pd paste as an internal electrode which can be sintered at low temperature and have cost down effect in mass productions. The multilayer piezoelectric actua-tors had no defects such as diffusions of internal electrode to ceramic bodies and shortages of internal electrodes. The multilayer piezoelectric actuators did not show the crack in the ceramics parts and the gapping phenomena in the external eletrodes when Ag paste was used as external electrodes. The multilayer piezoelectric actuators showed a maximum displacement of 4${\mu}{\textrm}{m}$ at 100V dc voltage and kept the maximum displacement constant for 300 seconds. The multilayer piezoelectric actuators showed good matching properties between ceramic bodies and AgPd internal electrodes. We confirmed the possibility of large-scaled production of the multilayer piezoelectric actuators with superior electrical properties and cost down effect using 70Ag/30Pd paste as an internal electrodes.

• 한국소음진동공학회논문집
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• 제26권4호
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• pp.458-468
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• 2016

Electromechanical model for analyzing a multimodal piezoelectric energy harvester comprising three connected beams is presented in this paper. This system consists of three beams which are connected alternately. The piezoelectric layer is only attached to the middle beam. With this special structural configuration, the first, second, and third natural frequencies are congregated so that the energy harvester can generate meaningful amount of power consistently when the main frequency component of the excitation varies around the lowest three natural frequencies of the harvester. To investigate the dynamic and electric response of the piezoelectric energy harvester, an electromechanical model is developed using the Kane's method and the accuracy of the model is validated by comparing the results obtained with the model with those obtained with the commercial software ANSYS. The results show that the piezoelectric energy harvester comprising three connected beams has much broader power generating frequency range than that of the conventional piezoelectric energy harvester.

• Steel and Composite Structures
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• 제35권1호
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• pp.1-12
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• 2020

This article deals with the buckling analysis in the plates containing carbon nanotubes (CNTs) subject to axial load. In order to control the plate smartly, a piezoelectric layer covered the plate. The plate is located in elastic medium which is modeled by spring elements. The Mori-Tanaka low is utilized for calculating the equivalent mechanical characteristics of the plate. The structure is modeled by a thick plate and the governing equations are deduced using Hamilton's principle under the assumption of higher-order shear deformation theory (HSDT). The Navier method is applied to obtain the bulking load. The effects of the applied voltage to the smart layer, agglomeration and volume percent of CNT nanoparticles, geometrical parameters and elastic medium of the structure are assessed on the buckling response. It has been demonstrated that by applying a negative voltage, the buckling load is increased significantly.