• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1087-1090
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• 2003

In this study, experimental procedures were suggested to investigate the sloshing behavior of a liquid storage tank subjected to inevitably external vibrating conditions. For this purpose. liquid storage tank with rectangular cross section was made of an acrylic resin for the visualization of liquid fluctuation. A specially designed vibrator was used to provide a specified vibrating condition to the liquid storage tank. Extrapolation technique was applied to determine sloshing natural frequency by using various sloshing frequencies at each vibrating displacement and liquid contents at a fixed vibrating frequency. Sloshing mode was also determined from continuous images or liquid fluctuation captured from a video camera. In addition, change in the height of the liquid free surface was measured by using a floating target and a laser displacement sensor. It is found that the suggested method can be applicable to identify the sloshing behavior of liquid storage tank with rectangular cross section.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.125-132
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• 2001

Heat dissipation technology using flow resonant phenomenon is a kind of new concept in heat transfer area. A vibration exciter is needed to generate air turbulence which has the natural shedding frequency of heat system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator. An analytical dynamic model for this mechanical vibration exciter is presented and its' validity is verified by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. And in the experiment, the feedback control is used. During the experimental verification phase, it turns out the high modal resonant characteristics of vibrating plate are the major barrier against obtaining a high bandwidth vibration exciter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.664-667
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• 2001

A flat-type L$_1$-B$_{8}$ Mode Ultrasonic motor(USM) uses longitudinal-bending multi-mode vibrator which is constructed with the metal-piezoceramic composite thin plate vibrator. Especially, the characteristics of vibrating displacement of the vibrator are important for the fabrication of USM. So, in this study, we tried to analyze them by the FEM(finite element method) simulation program. ANSYS 5.6 we used is a finite element software enabling the analysis of 2 or 3 dimensional structure of piezoelectric materials. Using this made us analyzing the resonance frequency and calculating displacement of vibrator and then the position of the projection.n.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.143-150
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• 2021

To develop the technique for predicting the horizontal displacement of a retaining wall induced by an earthquake, an equation of motion that depicts the retaining wall-soil vibrating system was derived. The resulting differential equation was solved using the Runge-Kutta-Nystr?m method. Considering the pre-mentioned derivation process, the analysis procedures for obtaining horizontal displacement induced by an earthquake were programmed. The core algorithm of the displacement-force relationship, which is the main engine of the developed program, was suggested. Considering the results obtained by adopting the developed program to the assumed retaining wall under an earthquake, the relationships between the time-displacement, time-force, and displacement-force were reasonable. According to the results computed by the program, the displacements to the front direction of the wall occurred, and the displacement per cycle converged after some cycles elapsed. Displacements with a natural period were calculated, which showed that the maximum displacement was observed when the natural frequency was slightly different from the excitation frequency rather than the same values of the two frequencies. This happens because the vibrating system was modeled by two springs with different stiffness.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.6-15
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• 2008

This paper deals with the aeroelastic instability of vibrating multiple blade rows under aerodynamic coupling with each other. A model composed of three blade rows, e.g., rotor-stator-rotor, where blades of the two rotor cascades are simultaneously vibrating, is considered. The displacement of a blade vibrating under aerodynamic force is expanded in a modal series with the natural mode shape functions, and the modal amplitudes are treated as the generalized coordinates. The generalized mass matrix and the generalized stiffness matrix are formulated on the basis of the finite element concept. The generalized aerodynamic force on a vibrating blade consists of the component induced by the motion of the blade itself and those induced not only by vibrations of other blades of the same cascade but also vibrations of blades in another cascade. To evaluate the aerodynamic forces, the unsteady lifting surface theory for the model of three blade rows is applied. The so-called k method is applied to determine the critical flutter conditions. A numerical study has been conducted. The flutter boundaries are compared with those for a single blade row. It is shown that the effect of the aerodynamic blade row coupling substantially modifies the critical flutter conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.308-315
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• 2010

This study introduces a new technique to estimate modal parameters of a vibrating string using motion pictures. The approach requires two motion pictures for a vibrating string captured simultaneously by typical potable digital cameras or camcorders. Applying the space intersection theory and the space resection theory in photogrammetry, the steroscopic images for the string are constructed from two flat plane pictures. Then the three dimensional displacement components of the string are extracted by a multiple template matching technique. Finally the modal parameters of the string are estimated from the resulting displacement time histories. The accuracy of the approach has been examined through a small-scale mock-up of a string.

• Proceedings of the Korea Contents Association Conference
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• 2014.06a
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• pp.225-226
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• 2014

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1874-1881
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• 2002

Heat dissipation technology using the flow resonant phenomenon is a kind of a new concept in the heat transfer area. A vibration exciter is needed to enhance air flow mixing which has the natural shedding frequency of thermal system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator with a displacement estimator using strain gage. An analytical dynamic model for this mechanical vibration exciter is presented and its validity is checked by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. During the experimental verification phase, it turns out the high modal resonant characteristics of a vibrating plate are a major barrier against obtaining a high bandwidth vibration exciter.

• Journal of Sensor Science and Technology
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• v.19 no.5
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• pp.361-368
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• 2010

ACROSS device, which is composed of an implantable microphone, a signal processor, and a vibrating transducer, is a fullyimplantable middle ear hearing device(F-IMEHD) for the recovery of patients with hearing loss. And since a microphone is implanted under skin and tissue at the temporal bones, the amplitude of the sound wave is attenuated by absorption and scattering. And the vibrating transducer attached to the ossicular chain caused also the different displacement from characteristic of the stapes. For the gain control of auditory signals, most of implantable hearing devices with the digital audio signal processor still apply to fitting rules of conventional hearing aid without regard to the effect of the implanted microphone and the vibrating transducer. So it should be taken into account the effect of the implantable microphone and the vibrating transducer to use the conventional audio fitting rule. The aim of this study was to measure gain characteristics caused by the implanted microphone and the vibrating transducer attached to the ossicle chains for the gain compensation of ACROSS device. Differential floating mass transducers (DFMT) of ACROSS device were clipped on four cadaver temporal bones. And after placing the DFMT on them, displacements of the ossicle chain with the DFMT operated by 1 $mA_{peak}$ current was measured using laser Doppler vibrometer. And the sensitivity of microphones under the sampled pig skin and the skin of 3 rat back were measured by stimulus of pure tones in frequency from 0.1 to 8.9 kHz. And we confirmed that the microphone implanted under skin showed poorer frequency response in the acoustic high-frequency band than it in the low- to mid- frequency band, and the resonant frequency of the stapes vibration was changed by attaching the DFMT on the incus, the displacement of the DFMT driven with 1 $mA_{rms}$ was higher by the amount of about 20 dB than that of cadaver's stapes driven by the sound presssure of 94 dB SPL in resonance frequency range.

• Tunnel and Underground Space
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• v.4 no.3
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• pp.297-304
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• 1994

This study aimed at analysis of induced stress and deformation behavior in rock mass around coal seams of Sam Chuck coal mine. For this study Vibrating Wire Stressmeters and Multi-point Borehole Extensometers were installed in the area of coal shale near coal seams. Induced stress and displacement in this area were coutinuously increased for 6 days from the begining of measurement, and then converged. But induced stress and displacement occurred when there were another openings by tunnelling and mining. The value of final induced stress was 21.8kgf/$\textrm{cm}^2$, displacement of rod extensometer was 1.3 mm at arch. Especially, over 1 mm of displacement between E2 and E3 in rod extensometer was measured.