• Title, Summary, Keyword: endcap

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Applied Voltage Dependence of the Displacement Characteristics on The Cymbal Actuator (심벌 액츄에이터의 변위특성에 대한 인가전압 의존성)

  • 최성영;김진수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.235-238
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    • 1998
  • In this study, the cymbal actuators with brass and bronze endcap at various endcap thickness were fabricated, and then the displacement vs applied voltage relation and position from the center of endcap relation were investigated The displacement values of all cymbal actuator were measured using laser vibrometer. The displacement of the cymbal actuator was increased linearly with increasing applied voltage. The cymbal actuator with 0.15mm thick brass endcap show approximately 1.3$\mu\textrm{m}$ displacement more than cymbal actuator with uniformly thick bronze endcap. The displacement about 3mm in diameter at the center of the endcap was uniform and rapidly decreased away from 3mm in diameter at the center of the endcap.

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Displacement Characteristics of Cymbal Actuator with Metal Endcap Structure (금속 앤드캡 구조에 따른 심벌 액츄에이터의 변위 특성)

  • Choi, Sung-Young;Kim, Jin-Soo
    • Proceedings of the KIEE Conference
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    • pp.844-846
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    • 1998
  • In this study, Brass endcap with 2, 3, 5, and 7mm contact surface and 0.6, 0.9, 1.2, 1.5mm conical cavity depths was fabricated by the punch die while keeping the cavity diameter constant 9.25mm then displacement characteristics of the cymbal actuators with each of brass endcap thickness were measured under an applied voltage $60V_{max}$. Dispacement increased with increasing contact surface and resonant frequency decreased with increasing contact surface, cymbal actuator with 7mm contact surface and 1.5mm endcap cavity depth exhibits $35.89{\mu}m$ displacement and 18.8kHz resonant frequency, displacement increased with increasing endcap cavity depth while contact surface was kept constant at 3mm and Below a endcap thickness of 0.2mm, Differences in displacement between 1.2mm and 1.5mm cavity depth appeared at $0.18{\mu}m$. that is, displacement of cymbal actuator with 1.2mm over cavity depth saturated nearly.

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Analysis of Endcap Effect for MRI Birdcage RF Coil by FDTD Method (FDTD 방법을 이용한 MRI Birdcage RF Coil의 Endcap 효과 분석)

  • Chung Sung-Taek;Park Bu-Sik;Shin Yoon-Mi;Kwak June-Sik;Cho Jong-Woon;Kim Kyoung-Nam
    • Investigative Magnetic Resonance Imaging
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    • v.7 no.2
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    • pp.137-143
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    • 2003
  • Purpose : B1 field of birdcage RF (radiofrequency) coil that is used most for brain imaging in magnetic resonance imaging (MRI) decreases toward endring from the coil center. We investigated how much RE B1 homogeneity effect the endcap shield brings form the coil center as it towards to endcap region. Materials and Methods : We compared RF B1 field distribution by each finite difference time domain (EDTD) simulations for lowpass, highpass and hybrid birdcage RF coils. We selected the highpass birdcage RF coil that was the highest RF B1 field condition as simulation result, and studied how much RF B1 homogeneity effect was occurred when endcap shield was applied to endring area. Results : B1 field of the highpass birdcage RF coil was higher than other birdcage RF coil types as simulation result. However, the RF B1 homogeneity was lower than other coil types. RE B1 field of highpass birdcage RF coil with endcap shield is similar with RF B1 field of hybrid birdcage RF coil and the overall RE B1 homogeneity in sagittal direction was better. Conclusion In this paper, proposed method can apply improving RF B1 homogeneity of RF coil in clinical examination.

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A Study on the Characteristics of Windmill Type Ultrasonic Motor with Changed Endcap Shape Using FEM (FEM을 이용한 endcap 형상이 변형된 풍차형 초음파 모터의 특성연구)

  • Lee, J.H.;Park, T.G.;Kim, M.H.
    • Proceedings of the KIEE Conference
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    • pp.1500-1503
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    • 2002
  • In this paper, we proposed windmill type ultrasonic motor which has modified shape of Endcap. The motor was especially designed by FEM for high speed. As results, displacements of the windmill and the clover type motor was compared. Using clover type motor, more smooth rotation of rotor was achieved. If Z component of the displacement of the clover type motor can be applied for linear motor.

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A Study on the Characteristics of Windmill Type Ultrasonic Motor (풍차형 초음파 모터의 특성 연구)

  • Lee, Jae-Hyung;Park, Tae-Gone
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.636-640
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    • 2003
  • As industrial technology was developed, necessity for small size motor was increased on various fields such as medical treatment and robotics. The motor should be simple structure, and it has easy process of manufacture to overcome the limit of miniaturization. So, "the windmill type ultrasonic motor" is enough to satisfy these conditions. In this paper, windmill type ultrasonic motor which was proposed by B.Koc and K.Uchino, was analyzed and fabricated with modified endcap shape. Displacements of arms of the proposed endcap were compared with the previous endcap, using the finite element analysis program (ANSYS). Better rotational characteristics was expected in proposed model as result of FEA. Experimentally, rotary motors of 3.5 [cm] diameter were fabricated, and the speed and torque of the motor were measured. As a result, speed and torque were changed in proportion to the electrical input voltages. And low efficiency which was different from an expectation was obtained in this motor. So, various problems should be improved for practical use.

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Evaluation of Endcap Welding Test for a Nuclear Fuel Rod having External and Internal Tube Structure (내외부 이중튜브구조를 갖는 핵연료봉의 봉단마개 용접시험 평가)

  • Kim, Soo-Sung;Kim, Jong-Hun;Kim, Hyung-Kyu
    • Proceedings of the KSME Conference
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    • pp.1377-1380
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    • 2008
  • An irradiation test of a nuclear fuel rod having external and internal tube structure was planned for a performance. To establish fabrication process satisfying the requirements of irradiation test, micro-TIG welding system for fuel rods was developed, and preliminary welding experiments for optimizing process conditions of fuel rod was performed. Fuel rods with 15.9mm diameter and 0.57mm wall thickness of cladding tubes and end caps have been used and optimum conditions of endcap welding have been selected. In this experiment, the qualification test was performed by tensile tests, helium leak inspections, and metallography examinations to qualify the endcap welding procedure. The soundness of the welds quality of a dual cooled fuel rods has been confirmed by mechanical tests and microstructural examinations.

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Convective heat transfer on the rotor fan and endring of the TEFC induction motor with telemetry system (무선계측기를 이용한 회전자팬 및 엔드링에서의 대류 열전달)

  • Yun, Myeong-Geun;Ha, Gyeong-Pyo;Go, Sang-Geun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.4
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    • pp.510-519
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    • 1998
  • Recently, computer modelling is increasingly used as a design tool, which requires more detailed data for heat transfer coefficients in various regions of the induction motor. But there are little information about those of rotor fan and endring because of difficulty in measuring signals in rotating bodies. In the present studies, the temperature signals were precisely measured with self-developed telemetry system, which had multi-channels and high rotational speed. After some losses were compensated, the heat transfer coefficients of the rotor endring and fan surfaces were measured. Minimum heat transfer region was existed with endcap plate distance and maximum heat transfer was found at some rotor fan width. It was also studied that how the guide plate and endcap inside rib effected on the rotor heat transfer. The higher heat transfer were obtained with decreasing guide plate distance, increasing the number and height of endcap inside rib. The correlation equations of the results were obtained and compared with others. Above results of the heat transfer coefficients can be used as basic data for cooling design of the various kind of motors.

Design of a Push-Pull Type High Power Ultrasonic Transducer with the FEM (FEM을 이용한 Push-Pull형 고출력 초음파 트랜스듀서의 설계)

  • Yoon Yanggi;Roh Yongrae
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.373-376
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    • 2000
  • 기존의 Push-Pull 트랜스듀서보다 간단한 구조를 가지며 출력을 한층 더 높이기 위해서 실린더 중앙에 구동부를 둔 새로운 구조의 Push-Pull 트랜스듀서를 설계하고자 한다. 유한 요소 상용 Package인 ANSYS를 이용하여 트랜스듀서의 모델을 구성한 후, 분석 시 고려되어 지는 길이, 반경, Endcap Edge 형상에 대해 변수로 설정, 변수들의 변화에 대한 음압의 변화 경향을 조사하여 최대 음압을 구현하기 위한 최적 길이, 반경, Endcap Edge 형상을 설정하였다. Endcap의 형상이 수직, 삼각형 형태의 트랜스듀서에서 나타난 결과에서 힘의 전달이 Edge형상이 수직일 때보다는 삼각형일 때가 더 좋은 것을 볼 수가 있었다. 또한 기존의 트랜스듀서를 유한 요소로 설계를 하여서 분석을 하였고, 기존의 트랜스듀서와 비교해 본 결과, 최적 설계한 트랜스듀서가 구조적으로 더 단순한 구조임에도 불구하고 더 큰 음압을 구현할 수 있는 고출력 트랜스듀서라는 것을 입증하였다.

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Fabrication of the Windmill Type Ultrasonic Its Characteristics of Torque and Bidirectional Revolution (풍차형 초음파 전동기의 제작과 토크 및 정$\cdot$역회전특성)

  • Kim, Young-Gyun;Kim, Jin-Soo
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.3
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    • pp.105-109
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    • 2001
  • In this paper, the windmill type ultrasonic motors with 11.35 mm diameter, 2.87 mm thickness of metal endcap and 1.47 g weight were fabricated. Effects of slots and thickness on torque characteristic in the windmill type ultrasonic motor were investigated, when stator's slots were changed from 4, 6, 8 and thickness 0.15 mm, respectively. Specially designed metal endcaps with windmill shaped cutting can provide longitudinal and torsional displacements simultaneously as the ceramic disk vibrates radically. The windmill type ultrasonic motor has only three components: a stator element with windmill shape slotted metal endcap, a rotor and bearing. Ultrasonic motor stimulated to ultrasonic oscillations by piezoelectrics to drive a rotor via friction contact. The ultrasonic motor fabricated here was the windmill type ultrasonic motor operated by single-phase AC source. Bidirectional revolution using single-phase high frequency for driving the ultrasonic motor was presented.

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