• Title/Summary/Keyword: Laser vibrometer

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Design of Ultrasonic Vibration Tool Horn for Micromachining Using FEM (유한요소법을 이용한 초음파 진동 공구혼 설계에 관한 연구)

  • Lee, Bong-Gu;Kim, Kwang-Lae;Kim, Kang-Eun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.6
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    • pp.63-70
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    • 2008
  • Conical horn is used in many high frequency ultrasonic horns, to achieve a longitudinal vibration mode across a wide ultrasonic tool horn output surface. Modal analysis is method for designing tuned ultrasonic tool horn and for the prediction natural frequency of ultrasonic tool horn vibration mode. The design of ultrasonic horn is based on prototype estimate obtained by FEM analysis. The FEM simulated ultrasonic tool horn is built and characterized experimentally through laser vibrometer and electrical impedance analysis. In this paper, FEM analysis is developed to predict the natural frequency of ultrasonic tool horn and use of in the optimal design of ultrasonic horn shape.

Vibration Reduction of an Optical Disc Drive by Using Dynamic Vibration Absorber (동흡진기를 이용한 광디스크 드라이브의 진동저감)

  • 박준민;허진욱;이영원;서영선;정진태
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.706-711
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    • 2001
  • A dynamic vibration absorber(DVA) is developed to reduce the excessive focusing vibration of an optical disc drive(ODD) originated from the resonance of an wobble disc. We design the material properties of the DVA by FEM model such as Young's modules, damping coefficient, shapes and dimensions, analyze its dynamic characteristics and provide its design guide line for suppressing the vibration of an optical disc drive. To examine the performance. of the DVA, the vibration of the wobble disc and the feeding system is measured by using a laser vibrometer and the noise level is checked by using microphone. The result shows that the proposed DVA reduces the vibration and. the noise in an optical disc drive.

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A Development of the Dynamic Absorber and Damper for Vibration and Noise Reduction of the Personal Computer (PC의 진동/소음 저감을 위한 쿨링홴의 동흡진장치 및 절연장치의 개발)

  • Jung, Won-Young;Lee, Kyu-Ho;Chung, Jin-Tai
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.4
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    • pp.339-345
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    • 2011
  • The purpose of this study is reduction the vibration of the personal computer by developing the vibration absorber and damper. The eccentricity of the cooling fan causes the vibration of the computer. We designed the material properties of the vibration absorber and damper by FEM model within operation frequencies of the cooling fan. We experiment the overall analysis and system analysis by using a laser vibrometer. The result shows that the proposed dynamic absorber and damper reduce the vibration of the personal computer.

The Experimental Studies for Reducing Airflow-induced Vibration of Actuator Arms in HDDs (하드디스크 드라이브의 내부 유동에 의한 액추에이터 암의 진동 저감을 위한 연구)

  • Cho, Kwang-Pyo;Yoo, Jin-Gyoo;Rhim, Yoon-Chul
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.670-675
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    • 2003
  • With the increase in recording density and higher rotation speeds, the aerodynamic aspect of hard disk drives (HDDs) is now quite significant. To achieve high TPI (tracks per inch) for hard disk drives, the actuator must induce less air turbulence. Also, alternative cross sections for the actuator arms are proposed for the reduction of air turbulence. In this study, off-track vibration of actuator arms used in of 3.5" hard disk drives with different cross sections have been measured by using Laser Doppler Vibrometer (LDV). It has been found that the vibration of the actuator arms with modified cross sections is lower than the conventional one.

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A Laser Doppler Vibrometer Featured with the In-housed Mechanism for Adaptive Compensation of Body Vibration (자체진동의 보상을 위한 레이저 도플러 계측 신호 적응 진동보상 기법 연구)

  • Lee, Jae-Sik;Chang, Tae-Gyu;Kim, Jae-Hwa;Kim, Ho-Seong;Kang, Min-Sig
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.50 no.8
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    • pp.392-399
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    • 2001
  • This paper presents an auxiliary beam-assisted adaptive compensation technique applied to alleviate the problem of LDV's body vibration. The LMS algorithm is applied to adaptively compensate the body vibration utilizing the reference signal provided by the auxiliary beam. The usefulness of the proposed technique is verified via computer simulations performed for diverse types of target signals and body vibration.

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Placing Constrained Layer Damping Patches Using Reactive Shearing Structural Intensity in Order to Reduce the Radiated Sound Power of a Air-Conditioner Outdoor Unit (반동 전단 구조 인텐서티 측정에 의한 제진재 적용과 그에 따른 에어컨 실외기 구조 방사 소음 저감)

  • 김규식;강연준;진심원;정인화;이정우
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.333-337
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    • 2003
  • The use of reactive shearing structural intensity to place small patches of constrained layer damping material in order to achieve the largest reduction in the radiated sound power of Air-conditioner outdoor unit is described. The normal surface velocity of each panel was measured using a laser doppler vibrometer. Experimental results indicated that patches of constrained layer damping material placed over areas of high reactive structural intensity reduced the radiated sound power significantly more than patches of the same area placed over areas of low reactive structural intensity

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In-plane Vibration Characteristics of Piezoelectric Ring Transducers (링형 압전 변환기의 면내 진동 특성)

  • Piao, Chunguang;Kim, Jin Oh
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.10
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    • pp.780-787
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    • 2014
  • This paper experimentally deals with the vibration characteristics of flat ring transducers used for ultrasonic sensors and actuators. Radial vibration mode, which is the fundamental mode of a thin piezoelectric transducer, was measured by a laser in-plane vibrometer. An impedance analyzer was used to measure natural frequencies. The results measured by experiments verified theoretical predictions. The vibration characteristics of ring transducers were identified according to the outer diameter size. The shape of the fundamental mode is almost uniform but slightly decreases from the inner to the outer circumferential surfaces. The natural frequency of the fundamental mode decreases as the outer diameter increases. It appears that the ring type transducer is suitable to excite uniformly distributed vibration on a flat surface.

Design of Cylinder Horn for Ultrasonic Welding (초음파 용접용 실린더 혼의 설계)

  • Kim, Sun-Rak;Lee, Jae-Hak;Yoo, Choong-D.
    • Journal of Welding and Joining
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    • v.27 no.4
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    • pp.60-66
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    • 2009
  • The cylinder horn is designed to increase uniformity of the displacement on the output face through simulation and experiments for the simple cylinder, spool and step horns. The modal analysis is conducted numerically to calculate the vibration mode and stress distribution of the cylinder horn, and the design of experiment (DOE) technique is employed to determine the optimum configuration of the spool horn. Displacement of the cylinder horn was measured using the Laser Doppler Vibrometer (LDV), and experimental results show good agreements with the predicted results. It appears that uniformity higher than 95% can be achieved with the spool horn when the proper dimension of the groove is used.

A Study on the Eavesdropping of the Glass Window Vibration in a Conference Room (회의실내 유리창 진동의 도청에 대한 연구)

  • Kim, Seock-Hyun;Kim, Yoon-Ho;Heo, Wook
    • Journal of Industrial Technology
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    • v.27 no.A
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    • pp.55-60
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    • 2007
  • Possibility of the eavesdropping is investigated on a conference room-glass window coupled system. Speech intelligibility analysis is performed on the eavesdropping sound of the glass window. Using MLS(Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the glass window are measured by accelerometer and laser doppler vibrometer. MTF(Modulation Transfer Function) is used to identify the speech transmission characteristics of the room and window system. STI(Speech Transmission Index) is calculated by using MTF and speech intelligibility of the vibration sound is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared.

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Characteristics of polycrystalline 3C-SiC micro resonator (다결정 3C-SiC 마이크로 공진기의 특성)

  • Lee, Tae-Won;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.69-70
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    • 2008
  • Micro resonators have been actively investigated for bio/chemical sensors and RF M/NEMS devices. Among various materials, SiC is a very promising material for micro/nano resonators since the ratio of its Young's modulus, E, to mass density, $\rho$, is significantly higher than other semiconductor materials, such as, Si and GaAs. Polycrystalline 3C-SiC cantilever with different lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and its fundamental resonance was measured by a laser vibrometer in air and vacuum at room temperature, respectively. For the cantilever with $100{\mu}m$ length, $10{\mu}m$width and $1.3{\mu}m$ thickness, the fundamental frequency appeared at 147.2 kHz.

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