• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.982-982
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• 2005

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.484-490
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• 2008

For CSLDV, the Chebyshev demodulation (or polynomial) technique and Hilbert transform approach have been used for mode shape reconstruction with harmonic excitation. In this paper, the Hilbert-Huang transform approach was applied as an alternative to impact excitation cases in terms of a numerical approach. The vibration of the tested structure is modeled using impulse response functions. In order to verify this technique, a simply supported beam was chosen as the test rig. With additional innovative steps which are the ideal-band pass filter and the nodal point determination, Hilbert-Huang transformation can be used for a good mode shape reconstruction even in the impact excitation case.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.414-419
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• 2003

There are some methods fur extracting mode shapes from a continuously scanned data such as a modulation, Chebyshev polynomial, and Hilbert approach. In this paper, Chebyshev and Hilbert approaches were investigated through the numerical experiment first. As some experimental parameters were altered with small quantities, data were checked and plotted. From those results, the effects of unexpected parameters will be configured. And then, it will be actually helpful to select the proper method for specific testing environments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.241-246
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• 2002

Usually vibration properties are obtained from frequency response functions or impulse response functions of a system. Since the contact type sensors can affect the characteristics of vibrating systems, the non-contact type sensors such as laser Doppler vibrometer (LDV) are being widely used. Currently researches are being carried out in terms of modal analysis using a scanning vibrometer. For the continuous scan; the Chebyshev demodulation (or polynomial) is apparently suggested to extract the mode shapes. With single frequency sinusoidal excitation, this approach is well fitted. In this research, the Chebyshev demodulation technique has been applied to the impact excitation case. The vibration of the tested structure is modeled using impulse response functions. The technique is also adopted to the random excitation case. In order to verify the technique, a simply supported beam was chosen as the test rig. The calculation modules are developed by using MATLAB$\^$(R)/ in WindowsNT$\^$(R)/ environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.392-397
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• 2001

This paper concerns on modal analysis of mechanical structures by using a continuous scanning laser Doppler vibrometer. In modal analysis the Hilbert transform based approach is superior to the Fourier transform based approach because of its fine accuracy and its flexible experimental settings. In this paper the Hilbert transform based approach is extended to measure area mode shape data of a structure by simply modifying the scanning pattern ranging the entire surface of the structure. The effectiveness of this proposed method is illustrated along with results of numerical simulation for a rectangular plate.