• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.274-280
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• 2002

This paper addresses the vibration mode shape measurement technique utilizing a Continuous Scanning Laser Doppler Vibrometer (CSLDV). The continuous scanning capability is added to the conventional discrete Laser Doppler Vibrometer by reflecting the laser beams on the surface of the object using two oscillating mirrors. The bow scanning resulted from the proposed scanning method is eliminated by feedback control. The velocity output signal from the CSLDV is modulated to give the spatial velocity distribution in terms of coefficients which are obtained from the Fast Fourier Transformation of the time dependent velocity signal. Using the Chebyshev series form, the analysis of the vibration mode shape techniques for straight Bine scanning and 2 dimensional scanning are presented and discussed. The performance of the proposed SLDV is presented using the experimental results of the vibration mode shape of a plate

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.734-741
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• 2003

This paper addresses the vibration mode shape Measurement technique utilizing a Continuous Scanning Laser Doppler Vibrometer (CSLDV). The continuous scanning capability is added to the conventional discrete Laser Doppler Vibrometer by reflecting the laser beams on the surface of the object using two oscillating mirrors. The bow scanning resulted from the proposed scanning method is eliminated by feedback control. The velocity output signal from the CSLDV is modulated to give the spatial velocity distribution in terms of coefficients which are obtained from the Fast Fourier Transformation of the time dependent velocity signal. Using the Chebyshev series from, the analysis of the vibration mode shape techniques for straight line scanning and 2 dimensional scanning are presented and discussed. The performance of the proposed SLDV is presented using the experimental results of the vibration mode shape of a cantilever and plate

• ETRI Journal
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• v.29 no.5
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• pp.694-696
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• 2007

This letter presents an adaptive coefficient scanning method for intra mode coding in H.264. The proposed adaptive scanning uses six alternative scanning orders based on the intra prediction mode. Experimental results show that the proposed method improves the coding efficiency up to 3% compared to conventional scanning methods without additional computations.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.99.3-99
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• 2001

In fluorescence mode confocal scanning microscope, level of detected signal is very low. In object scanning type confocal scanning microscope, the additional optical system with objective lens and plane mirror was proposed to increase signal intensity, but there was none for beam scanning type confocal scanning microscope. We propose reflecting optical systems which improve signal intensity in beam scanning type confocal scanning microscope. We choose one of the proposed optical systems and design the optical system, i.e., select optical components and assign distances between the selected components. To design the optical system, we use finite ray tracing method and make cost function to be minimized.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2560-2567
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• 2000

When spatially dense velocity distribution is measured by a scanning laser Doppler vibrometer, the Fourier transform method provides the real and imaginary parts of the mode shapes in the form of a polynomial. However the Fourier transform method is often impractical because the independent decomposition property of cosine and sine components into real and imaginary parts, respectively, does not hold due to the leakage problem which commonly occurs in the Fourier transform of harmonic signals. To deal with this problem, a Hilbert transform method is newly proposed in this article. The proposed method is free from the leakage problem and relatively robust to the scanning error. A simulation example is provided to verify the effectiveness of this method.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.420-425
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• 2000

When spatially dense velocity distribution is measured by a scanning laser Doppler vibrometer, the Fourier transform method provides the real and imaginary parts of the mode shapes in the form of a polynomial. However the Fourier transform method is often impractical because the independent decomposition property of cosine and sine components into real and imaginary parts, respectively, does not hold due to the leakage problem which commonly occurs in the Fourier transform of harmonic signals. To deal with this problem, a Hilbert transform method is newly proposed in this article. The proposed method is free from the leakage problem and relatively robust to tire scanning error. A simulation example is provided to verify the effectiveness of this method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.531-535
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• 2000

If the displacement of the structure is obtained by integrating the signal from accelorometer and laser, the vibration mode can be examined. This conventional method, however, has the disadvantage of the necessity of multiple accelerometers and many data processing steps such as frequency response function(FRF). In order to get smooth mode shape, we should also use algorithms of cubic spline or others. In this paper, we propose a method which gets the mode shape by using the velocity signal directly obtained from the plane scanning. In this method, we just use coefficients and phases for specific frequency.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.1
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• pp.9-15
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• 2012

This paper shows an effective scanning trajectory for a mine detection device that is one of the mission equipments of unmanned ground vehicle. The mine detection device is composed of a mine-detection sensor, and a 4 DOF manipulator enabling sensor position control. There are three modes that manage the mine detection device: passive, semi-automatic, and automatic. The automatic mode is used the most. This paper suggests a scanning method that makes shape of 8. This method prevents missing target area and enhances scanning speed when the mine detection device scans the ground surface in automatic mode. The suggested method is verified by simulations and experiments.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.137-143
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• 2013

This study presents comparison results between axial and spiral scanning in the head and chest region with 64 MDCT to evaluate organ doses in infants and toddlers, who are more radiosensitive to radiation than adults and rise in the number of CT examinations, during CT scanning. Organ doses were significantly lower in spiral scanning than axial scanning regardless of scanned regions. The average organ dose for the chest scan using pitch of 1.355 was found to be significantly higher(average -12.03%) than for the other two pitch settings(0.525 and 0.988) in the spiral scanning mode compared with the axial one. Organ doses in the spiral scanning mode were lower by average 20.54% than the axial scanning mode. The results of the study that evaluated organ doses with an anthropomorphic phantom will help to demonstrate the result values of Monte Carlo simulations and make a contribution to more accurate evaluations of organ doses in toddlers undergoing a CT examination.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.2
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• pp.28-33
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• 2008

In a scanning electron microscope (SEM), outside acoustic noise causes image noise that distorts observations of the specimen being examined. A SEM that is less sensitive to acoustic noise is highly desirable. This paper investigates the image noise problem by addressing the mode shapes of the base plate and the transmission path of the acoustic noise and vibration. By arranging the position of the rib, a new SEM base plate was developed that had twisting as the 1st and 2nd modes. In those two twisting modes, vibration nodes existed near the center of the base plate where the specimen chamber is placed. Less vibration was transmitted to the chamber and to the specimen by the twisting modes compared to bending ones, which are the 2nd and 3rd modes for a rectangular plain base plate. An SEM with the developed base plate installed exhibited a significant reduction of image noise when exposed to acoustic noises below 250 Hz.