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Park, Soon-Hong;Seo, Sang-Hyun
- Transactions of the Korean Society for Noise and Vibration Engineering
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- v.22 no.8
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- pp.756-762
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- 2012
A method of the low-frequency noise reduction in an enclosure by using an array of Helmholtz resonator is presented. An integral form of equation, which represents the acoustical coupling between the internal sound field and the resonator array, is formulated so that the boundary element method can be applied to solve the coupling problem. It is shown that the resonator array on the surface of the enclosure can be regarded as impedance patches on the boundary element. Experiments on a simple enclosure acoustically coupled with an array of resonators are conducted to verify the method. The predicted noise reduction by the boundary element method shows good agreement with the measured one. The effects of the resistance of resonators as well as the number of resonators on the noise reduction are demonstrated. As a practical example, the presented method is applied to the payload fairing of a space launcher with resonator arrays. It is demonstrated that the resistance of resonators affects significantly the required number of resonators to achieve a desired noise reduction.
https://doi.org/10.5050/KSNVE.2012.22.8.756 인용 PDF KSCI

Ji, Sumin;Hong, Chinsuk;Jeong, Weui-Bong;Kim, Tae-Hoon
- Transactions of the Korean Society for Noise and Vibration Engineering
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- v.25 no.3
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- pp.191-198
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- 2015
Noise propagated through the ventilation openings of enclosures is actively controlled using an FIR filter. The enclosures considered in this paper are used for isolating noise due to machinery. This method is of limited use because of the ventilation openings through which most of noise is propagated. Feedforward control strategy is incorporated to minimize the acoustic power propagated through the openings. For the real-time implementation, although it is numerical study, the controller is implemented using an FIR filter. The acoustic transfer functions of the pressure on the openings of the enclosure to the primary source and to the secondary source are numerically calculated using the boundary element method. The performance analysis of the active control is conducted with the time-domain simulation using Matlab Simulink.
https://doi.org/10.5050/KSNVE.2015.25.3.191 인용 PDF KSCI KPUBS HTML

Chung, Sung-Hak;Song, Kee-Hyeok
- Journal of the Korea Society of Computer and Information
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- v.19 no.5
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- pp.37-42
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- 2014
The objective of this study is the frequency of the noise source 170 dB level of impulsive sound attenuation performance by earplugs to identify, to analyze the frequency characteristics of a shape and pattern. The attenuation performance of the impulsive noise by the frequency levels on the Combat Arm and 3M Form types 1100 Earplugs were evaluated. In order to check the sound attenuation performance of the B&K head and torso simulator and sound attenuation performance of the ear simulator data was verified. Previous studies have most impact, even in the noise source and the impulse noise level is 140 dB, but this study is higher than that of the impulsive noise source features. The results of the impulse noise attenuation effect is frequency-dependent mean 28.58 dB.
https://doi.org/10.9708/jksci.2014.19.5.037 인용 PDF KSCI