• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.525-528
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• 2000

Piezoelectric ceramics can provide electro-mechanical transduction with high stresses but low displacement. To obtain larger displacements, several mechanical amplifying structures have been used. High alternating displacements can be obtained using resonant structure. In this paper, we designed three kinds of the bolt-tightened Langevin type ultrasonic vibrators whose resonant frequencies are 30[kHz], 40[kHz]. FEM(Finite Element Methode) was employed to calculated the resonant frequencies and maximum displacements of designed vibrators. The designed resonant frequencies and computer calculated frequencies were coincided. When input voltages were increased, maximum displacements were also raised. ANSYS was used to find resonant frequencies and calculate displacements of vibrators.

• 한국음향학회지
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• 제22권8호
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• pp.629-636
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• 2003

의료용 초음파 진단 장치나 표적을 탐지하는 소나 등에 사용되는 초음파 트랜스듀서 어레이는 정도 높은 정보를 얻기 위해 목적에 맞는 지향특성이 요구되어진다. 본 연구에서는 사용 목적 따라 지향 특성을 가변할 수 있는 초음파 트랜스듀스 어레이를 제안하였다. 제안한 초음파 트랜스듀서 어레이는 전기적 용량으로 제 2 차 모드의 효율을 제어할 수 있는 2층 구조 트랜스듀서를 이용하여 트랜스듀서 어레이의 빔 폭을 제어하였다. 이것을 시험 제작하여 이론 및 실험적으로 해석한 결과 주엽의 -3 dB 빔 폭을 7.6° ∼ 16.2°의 범위에서 제어 가능함을 확인하였다.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1511-1517
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• 2012

진공유리 배기공정을 위해 진공챔버나 진공튜브를 이용하는데 챔버 혹은 튜브 내부 전체를 진공으로 만들기 위한 시간과 경비가 과도하게 요구된다. 이러한 문제점을 해결하기 위해 상압에서 진공배기 및 초음파 접합이 동시에 가능한 복합기를 개발하고자 하였는데, 이 경우 진동자인 피에조 온도가 과도하게 상승하여 복합기의 냉각을 최적화할 필요성이 대두되었다. 따라서, 본 연구에서는 수치해석 및 실험을 통해 자연대류 및 강제대류 냉각방식의 효과를 규명하였고 이를 통해 진공 배기 및 초음파 접합 복합기의 냉각 성능을 최적화하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.393-397
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• 2001

A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramics element as a driving element. That is, L$_1$-B$_4$ linear ultrasonic motor can be constructed using a multi-mode vibrator of longitudinal and bending modes. The simulation with variation of material characteristics of piezoceramic were performed as use of finite element analysis ANSYS 5.5, such as elastic compliance, piezoelectric constant, electro-mechanical coupling coefficient, poisson's ratio and density. The results of simulation, elastic compliance constant s$_{11}$ and piezoelectric constant d$_{31}$ had the most of influence on the elliptic-motion. This results consist with using transverse effect of material. The used motor were piezoceramics of 4 layers, and the dimensions were 65$\times$5$\times$3.5mm(LxWxt).).

• 한국음향학회지
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• 제16권5호
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• pp.12-17
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• 1997

본연구에서는 압전세라믹을 이용하여 외부에 노출된 유리판에 부착된 물방울을 효율적으로 제거할 수 있는 초음파 물기 제거장치를 개발하였다. 초음파 진동장치의 제작을 위하여 유한요소법을 사용하여 유리면의 진동특성을 분석하였고 이 결과를 바탕으로 체적의 효과를 얻을 수 있는 초음파 진동액츄에이터의 구조와 규격을 결정하였다. 진동장치의 제작에 있어서는 시뮬레이션 결과를 바탕으로 진동의 균일한 분포를 위해서 보조진동판을 사용하였고 주어진 크기의 유리판의 최적조건을 찾기 위해 보조진동판과 유리판의 다양한 두께와 압전소자의 크기와 두께에 따라서 그 특성을 알아보고 성능을 평가하였다. 구동 발진기는 유리판의 공진점을 추적하기 위해 일정 주파수대역을 스위핑하는 가변주파수 발진기로 제작하였다.

• 센서학회지
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• 제13권6호
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• pp.417-423
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• 2004

In order to obtain wide-beam characteristics and variable resonant frequency of a ultrasonic transducer for the array source, an electrode of transverse mode piezoelectric vibrator is divided, and an electronic inductance is connected to the divided electrodes. The electronic inductance is made by GIC (General Impedance Converter) circuit. Because the GIC circuit is made of OP-Amps and other passive elements, the value of the inductance can be selected easily. As the results, the electronic inductance is variable in the range from 0.2 mH to 1.2 mH. Using the inductance, the resonance frequency of the transducer can be changed in the range from 73 kHz to 86 kHz. In the directivity of the transducer, it is confirmed that the beam width of the transducer is wider than $80^{\circ}$ at -3 dB in water.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.343-343
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• 2008

Newly designed structure of a thin ultrasonic rotary motor was proposed. Thin brass plate was used as a cross shaped vibrator and eight ceramic plates were attached on the upper and bottom sides of the brass plate as in Figure 1. The thin type ultrasonic motor has the structure adherent piezoelectric ceramic on the top and bottom surface of the thin elastic body. The direction of polarization is decided so as to occur the elliptical displacement in regular sequence at touch point A, B, C and D of stator contacted with rotor. By applying two electric fields which have 90 degree phase difference on the ceramics, each contact points make rotational displacements as in figure 2. Finite element analysis program ATILA was used to find the optimal size of the stator. As a result of the simulation, elliptical displacements of the tips were obtained at off-resonance frequencies. The maximum displacements of the contact tips were obtained at the length of 16[mm], width of 6[mm] and thickness of 0.4[mm]. Changes of the resonance frequencies were inversely proportional to the length of ceramic and proportional to the width of ceramic. Elliptical motions of the contact tips. of the stator were consistently obtained at off resonance frequencies. From a prototype motor, speed of 600[rpm] was obtained at 20[Vrms].

• 한국재료학회지
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• 제19권4호
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• pp.198-202
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• 2009

For use in ultrasonic actuators, we investigated the structural and piezoelectric properties of $(1\;-\;x)Pb(Zr_{0.515}Ti_{0.485})O_3$ - $xPb(Sb_{1/2}Nb_{1/2})O_3$ + 0.5 wt% $MnO_2$ [(1 - x)PZT - xPSN + $MnO_2$] ceramics with a variation of x (x = 0.02, 0.04, 0.06, 0.08). All the ceramics, which were sintered at $1250^{\circ}C$ for 2 h, showed a typical perovskite structure, implying that they were well synthesized. A homogeneous micro structure was also developed for the specimens, and their average grain size was slightly decreased to $1.3{\mu}m$ by increasing x to 0.8. Moreover, a second phase with a pyrochlore structure appeared when x was above 0.06, which resulted in the deterioration of their piezoelectric properties. However, the 0.96PZT-0.04PSN+$MnO_2$ ceramics, which corresponds with a morphotropic phase boundary (MPB) composition in the (1 - x)PZT - xPSN + $MnO_2$ system, exhibited good piezoelectric properties: a piezoelectric constant ($d_{33}$) of 325 pC/N, an electromechanical coupling factor ($k_p$) of 70.8%, and a mechanical quality factor ($Q_m$) of 1779. The specimens with a relatively high curie temperature ($T_c$) of $305^{\circ}C$ also showed a significantly high dielectric constant (${\varepsilon}_r$) value of 1109. Therefore, the 0.96PZT - 0.04PSN + $MnO_2$ ceramics are suitable for use in ultrasonic vibrators.

• 한국음향학회지
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• 제22권3호
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• pp.217-223
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• 2003

30 ㎑의 초음파 (ultrasonic wave)의 미세 진동에 의해서 유도된 음향유동 (acoustic streaming)에 의한 공기대류를 이용한 새로운 냉각방법을 소개한다. 초음파 진동은 압전소자 (piezoelectric device)에 의해서 얻어지며 50 m 정도의 진동진폭을 얻기 위해 기계적 진동 증폭자인 혼 (horn)을 추가하여 전체 진동 시스템이 공진하도록 구성된다. 음향유동에 의한 열전달 효과의 상승을 측정하기 위해 열원 (heat source) 및 열원 주위의 대기의 온도변화를 실시간으로 측정하였다. 초음파 진동 시작 후 시간지연 없이 음향유동이 유도되어 진동자 주위의 대량의 공기유동으로 인한 급격한 온도감소가 관찰되었다. 또한 열원과 진동자와의 거리가 방사 (radiation)되는 음파 (sound wave)의 반파장 (half wave length)의 정배수가 될 때 열원의 냉각효과가 극대화됨을 실험적으로 관찰하였다. 이는 음파의 공진현상에 기인한 것으로 이론적 고찰을 통한 검증 또한 수행되었다. 음향유동을 이용한 냉각법의 장점은 초음파 진동을 이용하기 때문에 무소음이며 이동 형태의 부품이 없기 때문에 반영구적으로 사용할 수 있다. 또한 기존의 전기모터를 이용한 냉각팬 (cooling fan)으로는 냉각이 어려운 초소형 기전시스템 (MEMS)의 냉각법으로 사용될 수 있는 첨단 냉각방법이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.109-109
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• 2009

This paper represented driving characteristic of a thin-type ultrasonic motor by fabricating and utilizing two kinds of drivers which could generate sinusoidal wave, square wave, respectively. A thin brass plate was used as a cross shaped vibrator and sixteen ceramic plates were attached on upper and bottom side of the brass plate. From the thin stator, elliptical displacements of the four contact tips were obtained. Speed, torque, and current were measured by applying sinusoidal waves through driving equipment such as function generator, power amplifier: to measure characteristic of the motor. As a result, the speed and the torque changed linearly at either driving frequency of 88.6 ~ 87.6[kHz] or voltage of 24~36[V]. Two-drivers which generate sinusoidal waves and square waves were designed respectively, and then were compared through some experiments in order to be put to practical use. In conclusion, the drivers had similar characteristic of speed-torque at similar frequency and voltage. It was able to control the motor linearly by using the driver generating square wave among two-drivers. Besides, it also was possible to make the drivers smaller.