• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.175-176
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• 2008

An ultrasonic motor of high torque with a new configuration for application in automobiles is proposed. The newly designed stator is two sided vibrator consisting of a toothed metal disk with a piezoelectric ceramic ring bonded on both faces of the disk which generates a flexural traveling wave along the circumference of disk. In this configuration, the displacement on the surface of stator may not be confined. It also produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric plates. It is possible to increase the torque by improving the vibration characteristics. To compute the vibration mode of the motor of diameter 48 mm, the finite element method was used. A 6th mode was chosen as the operation mode with a resonance frequency of about 64.4 kHz. According to this design and measured its performance, a prototype was fabricated. The performance measurement of the prototype motor showed that its stall torque was about 1.8 Nm and efficiency was 37 % at 60 % of the maximum torque.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.187-188
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• 2008

An ultrasonic motor of high torque with a new configuration for application in automobiles is proposed. The newly designed stator is a two sided vibrator consisting of a toothed metal disk with a piezoelectric ceramic ring bonded on both faces of the disk which generates a flexural traveling wave along the circumference of disk. In this configuration, the displacement on the surface of stator may not be confined. It also produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric plates. It is possible to increase the torque by improving the vibration characteristics. To compute the vibration mode of the motor of diameter 48 mm, the finite element method was used. A 6th mode was chosen as the operation mode with a resonance frequency of about 64.4 kHz. According to this design and measured its performance, a prototype was fabricated. The performance measurement of the prototype motor showed that its stall torque was about 1.8 Nm and efficiency was 37% at 60% of the maximum torque.

• 대한기계학회논문집A
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• 제27권3호
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• pp.363-371
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• 2003

This study is mainly concerned with phenomenon of cavitation-erosion on the several materials and corrosive liquids which were applied with vibrator(suggested by ASTM G 32, 20KHz, 50$mu extrm{m}$). The maximum erosion rate by cavitation erosion in both of distilled water and sea water appeared to be proportioned to their hardness and tensile strength. Cavitation weight loss and rate of cast iron in sea water condition were greater(approximately 3 times) than that in distilled water condition, however in case of stainless steel and brass the cavitation weight loss of composite materials were not so different in both of their conditions. Cavitation weight loss of composite materials were shown as below on this test, Duratough DL : Weight loss in sea-water condition were greater (approximately 2.3 times) than it's distilled water condition. The main tendency of cavitation erosion for metals appeared that small damaged holes causing by cavitation erosion was observed with radial pattern. On the other hand, the tendency for composites appeared that small damaged holes were observed randomly.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.227-233
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• 1999

This study is mainly concerned with phenomenon of cavitation-erosion on the several materials and corrosive liquids which were applied with vibrator (suggested by ASTM G-32, 20KHZ, 24{$mu}m$).The main results obtained are summarized as follows ; (1) The maximum erosion rate by cavitation erosion in both of fresh-water and sea-water appeared to be proportioned to their hardness and tensile strength. (2) Cavitation weight loss and rate of cast iron in sea-water condition were greater (approximately 3 times) than that in distilled-water condition, however in case of stainless and brass the cavitation weight loss and their rates were not so different in both of their conditions. (3) Cavitation weight loss of composite materials were shown as below on this test, DuraTough DL : Weight loss in sea-water condition were greater (approximately 2.3 times) than it's fresh-water condition. (4) As the result of observation with digital camea of specimens, the main tendency of cavitation erosion for metals, was that small damaged holes causing by cavitation e개sion was appeared with radial pattern, and composites materials was that small damaged holes were appeared randomly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.280-281
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• 2009

Piezoelectric vibrators can be good replacements of electric motors to excite touch screen of a mobile device owing to small volume and low power consumption. One problem to be solved yet for real application is larger excitation force or moment than available currently. More efficient excitation by a piezoelectric vibrator could be achieved by operating at one of resonance frequencies of the system, which must also be as close as possible to frequency range where index finger is most sensitive and increasing transmission force or moment at that frequency. In this study, dynamic models are derived for the piezoelectric exciter and an adhesive viscoelastic layer, which connect the exciter to the screen. The adhesive layer is modeled as distributed stiffness by considering its geometric shape to relative to the piezoelectric exciter. Then, equations of motion for the piezoelectric exciter and the adhesive layer are derived using Hamilton's principle. Based on this model, dynamic characteristics of the exciter will be designed to maximize the force or moment transmitted onto the screen structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.299-302
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• 2002

Characteristics of the twin fluid spray with ultrasonic forcing are examined in order to obtain the high efficiency of cold fog spray of the automatic pest control machine which has been widely used for the equipment cultivation recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive vibrator of ${\pi}type$ with 28 kHz are applied as the ultrasonic transducer. All experiments are made and observed in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving duality method by ultrasonic forced within liquid, and a combined use method with both of the indirect vibration method and the improving quality method. In results, It was clarified that the ultrasonic effects the atomization of spray droplets and its efficiency is about $10{\%}$ and especially much more in the case of the combined use method.

• 대한기계학회논문집A
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• 제41권5호
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• pp.415-420
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• 2017

과소 구동 전동의수는 가벼우며 비교적 경제적이라는 장점이 있다. 본 연구에서는 적응파지가 가능한 과소 구동 전동의수를 대상으로 경제적인 파지력 제어 시스템을 제안하였다. 근전도 신호로 구동되는 메인 케이블의 장력으로 파지력이 결정되므로 장력에 따라 사용자의 피부에 부착된 진동모터를 구동하는 촉감기반 피드백 시스템을 구성하였다. 진동 신호에 대한 사용자의 감각적 판단을 기반으로 파지력을 추정하고 제어하기 위하여 파지력과 진동 신호 간의 적절한 변환 관계를 수립하고 시제품 성능시험을 하였다. 최소한의 훈련으로 사용자들은 비교적 정확하게 파지력을 제어할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1153-1158
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• 2010

본 논문은 수평진동감쇠기를 제작하여 수평진동의 감쇠실험을 통해 선박에 적용될 수 있는 가능성을 확인한다. 시뮬레이션 툴은 매트랩을 사용하며, 실험장비는 축에 캠형의 불평형부하를 장착한 두 대의 유도전동기와 DSP 그리고 인버터 부로 구성된다. 유도전동기는 가진기와 감쇠기의 역할을 하고, DSP보드는 속도와 위상 및 벡터제어 등의 소프트웨어를 제어한다. 감쇠기의 속도와 위상각을 제어한 결과 가진기에서 발생한 수평진동의 감쇠가 양호함을 확인하였다.

• 한국음향학회지
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• 제20권5호
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• pp.54-60
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• 2001

본 논문에서는 휴대폰용 부저, 진동자 기능이 하나의 소자로 통합된 다기능 복합소자의 특성을 해석하기 위한 등가회로 해석법을 연구하였다. 전형적인 복합소자 제품에 대하여 부저, 진동 모드에 각각에 대한 등가회로를 구성하여 그 특성을 계산하였다. 이를 위해 우선 복합소자의 각 모드에 대한 동작원리를 규명하고, 그 원리에 따른 등가회로를 구성하여 복합소자의 동작특성을 시뮬레이션 할 수 있는 해석툴을 완성하였다. 해석법의 타당성은 그 결과를 실험결과와 비교함으로써 밝혔고, 계산 결과와 실제 측정결과가 잘 일치함을 알 수 있었다.

• 동력기계공학회지
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• 제13권3호
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• pp.65-71
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• 2009

This paper presents the energy harvesting technique which is carried out by vibration system with a piezoelectric element. In this study, low frequency characteristics of the piezoelectric element bonded to the aluminum cantilever were experimentally investigated. The piezoelectric element of size of $45L{\times}11W{\times}0.6H$ and piezoelectric constant($d_{31}$ ) of $-180{\times}10^{-12}C/N$ was used. The material of cantilever is an aluminum and two kinds of cantilever of which dimensions are (150, 190)$[mm]{\times}13[mm]{\times}1.5[mm]$ were experimented, respectively. The cantilever was fixed on the magnetic type vibrator and the vibrator was operated by power input with a sine wave. The characteristics of requency and mass variation of cantilever end part such as 0, 2.22, 4.34, 5.87, 8.66, 11.01 [g] were investigated. Finally, this paper suggests a method of generating electrical energy with a piezoelectric element using wind, an energy source that is easily applied and from which we can obtain "clean" energy.