• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1104-1112
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• 2004

In this paper, we establish measurement methods of vibration frequency for three-dimensional behavior measurement of large-scale structure using laser and high-speed CCD camera. We project the diode laser having a smaller fluctuation on the object plane attached to the structure and measure the displacement of the structure using a precise relative measurement algorithm. When we use high-speed(120 frames/sec) CCD camera, we can measure the vibration frequency having the uncertainty within 0.5% by taking FFT on the displacement, from 0Hz to 40Hz. And we also confirm the reliability and economical string of the suggested measurement method of vibration frequency of the structure by showing the accuracy of displacement measurement using laser is comparable to that of relative positioning methods using GPS.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.4
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• pp.361-372
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• 2010

Optical image stabilization is a technique to compensate the image blurring caused by some vibrations of camera at the exposure time. Pitching and yawing of camera are sensitive to the image quality so they are usually compensated by optical image stabilization. Corresponding pitching and yawing of a camera, a lens or the image sensor is translated in two-axis direction and then the optical path of camera is adjusted. In this paper, two-axis OIS actuator for mobile camera module is suggested and designed. The actuator is a voice-coil actuator that uses the electromagnetic force of voice-coil to make compensation motions. And ball bearing is used to reduce friction force. Magnetic attractive force between magnets and yokes acts as a preload and magnet springs. Prototype actuator is fabricated to measure the friction force and to verify the feasibility of the OIS actuator with ball bearing. At last, the actuator is improved in consideration of driving force and friction force. Design of experiments is used for designing the actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.626-629
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• 2007

Vibration originated from the fuel pump is transmitted to the fuel pump module and fuel tank. Fuel tank transmits it to chassis of vehicle. Also, noise perturbed through fuel and fuel tank is radiated out. Dynamic characteristics of fuel tank are composed of tank structure and containing fuel quantity. Therefore, this study is focused at fuel tank with various quantity. As a result, characteristics of vibration for various fuel quantity in a tank are identified as the more mass of fuel is, the less the 1st resonance frequency decrease. Also, between acoustic camera and mode shape of modal analysis are used for searching the positions of radiated noise and are found to be in accordance with each other.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.743-748
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• 2008

This paper presents an inertia type of piezostack based active mount for unmanned aero vehicle (UAV) camera system. After identifying the stiffness and damping properties of the rubber element and piezostack a mechanical model of the active mount system is established. The governing equation of mount is them derived and expressed in a state space farm. Subsequently, a sliding mode controller which is robust to uncertain parameters is designed in order to reduce the vibration imposed according to the military specification associated with UAV camera mount system operation. Control performances such as acceleration and transmitted force are evaluated through both computer simulation and experimental implementation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1278-1285
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• 2008

This paper presents an inertia type of piezostack based active mount fur unmanned aero vehicle (UAV) camera system. After identifying the stiffness and damping properties of the rubber element and piezostack a mechanical model of the active mount system is established. The governing equation of mount is then derived and expressed in a state space form. Subsequently, a sliding mode controller which is robust to uncertain parameters is designed in order to reduce the vibration imposed according to the military specification associated with UAV camera mount system operation. Control performances such as acceleration and transmitted force are evaluated through both computer simulation and experimental implementation.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1011-1016
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• 2015

Gas piping systems in power plants and factories are always influenced by the mechanical vibrations of rotational machines such as pumps, blowers, and compressors. Unusual vibrations in a gas piping system influence possible leakages of liquids or gases, which can lead to large explosive accidents. Real-time measurements of unusual vibrations in piping systems in situ prohibit them from being possible leakages owing to the repeated fatigue of vibrations. In this paper, a non-contact 3-dimensional measurement system that can detect the vibrations of a solid body and monitor its vibrational modes is introduced. To detect the displacements of a body, a stereoscopic camera system is used, through which the major vibration types of solid bodies (such as X-axis-major, Y-axis-major, and Z-axis-major vibrations) can be monitored. In order to judge the vibration types, an artificial neural network is used. The measurement system consists of a host computer, stereoscopic camera system (two-camera system, high-speed high-resolution camera), and a measurement target. Through practical application on a flat plate, the measured data from the non-contact measurement system showed good agreement with those from the original vibration mode produced by an accelerator.

• Transactions of the Society of Information Storage Systems
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• v.7 no.2
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• pp.70-74
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• 2011

The mobile camera module is a device to be inserted in the digital device for camera feature. The mobile camera module is being shaken by vibrations such as handshake during the exposure time. The clarity is compromised by these vibrations, thus the vibration is considered as an external disturbance. Moreover the use of mobile camera module has been being expanded for automotive vibration should be considered. These external disturbances can cause image blurring, thus optical image stabilization should be applied for image compensation. The compensator is fulfilled mechanically by movable lens group or image sensor that adjusts the optical path to the camera movement. Open loop control is useful for well-defined systems like compliant mechanism. Notch filter and lead compensator are designed and applied to improve the stability and bandwidth. The final level of image compensating is confirmed by image processing with MATLAB and CODE V to verify the better performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.721-722
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• 2012

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.767-773
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• 2010

In the present work, vibration control performance of piezoactuator-based active mount system for unmanned aero vehicle(UAV) equipment is evaluated via hardware in the loop simulation(HILS). At first, the vibration level of UAV is measured and from this vibration data, the proper piezostack actuator is selected. Then, the dynamic model of active mount system including four active mounts and UAV camera equipment is derived. In order to evaluate vibration control performance, the HILS system is constructed. The proposed mount is prepared as hardware part and the other mounts are considered in software part. A sliding mode controller is designed and implemented to the HILS system. Effective vibration control results are presented in both time and frequency domains.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.568-574
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• 2015

The present study was conducted by using stereo pattern recognition method(SPR method) to measure the displacement and vibration of an airplane wing in flight condition. A SPR based measurement system was developed using two visible light stereo cameras. The visible light stereo images were processed to obtain marker points by adaptive threshold method and marker filtering technique. The marker points were used to reconstruct 3D point, displacement, and vibration data. The SPR system was installed on F-16 fighter. The wing displacement and vibration were measured in flight condition. Therefore, this paper presents a possibility that SPR based measurement system using visible light stereo camera can be very useful for measuring displacement and vibration of an airplane in flight condition.