• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.193-195
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• 2006

In order to minimize the influence of aircraft noise in the vicinity of domestic airports, the establishment of proper land-use plan according to the influence scope of aircraft noise in the opening part of preparing a housing site around domestic airports is needed. For the purpose of doing it, the environmental impact assessment accompanied by the accurate prediction of aircraft noise distribution is preceded, and this paper describes the improvement plan for performing the trustworthy environmental impact assessment of aircraft noise in the neighborhood of domestic airports.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.774-779
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• 2004

This paper addresses the way in which we can find where impact noise sources are. Specifically, we have an interest in the case that the signal is embedded in noise. We propose a signal processing method that can identify impulsive sources’location. The method is robust with respect to noise; spatially distributed noise. This has been achieved by a beamforming method with regard to cepstrum domain is used. It is noteworthy that the cepstrum has the ability to detect periodic pulse signal in noise. Numerical simulation and experiments are performed to verify the method. Results show that the proposed technique is quite powerful for localizing the faults in noisy environments. The method also required less microphones than conventional beamforming method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.612-615
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• 2006

In this study, we compared and analyzed the floor impact noise insulation performance produced by the rating methods. The rating methods are using reversed A-weighting curve, A-weighted sound pressure levels(dB(A)). The results of this study are(1)dB(A) by the specified frequency is 0.5dB(A) at light weight and 2.5dB(A) at heavy weight upper than all pass dB(A)(2)the rating using reversed A-weighting curve is 5dB lower than dB(A)(3)the number of rating using reversed A-weighting curve mainly depends on impact noise pressure level of 63Hz in heavy weight but dB(A) does not.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1062-1068
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• 2007

We are using COS to block the excess current and to protect the transformer. But the fuse of COS is melt due to the overload resulting from the excess current flows and it destroys an air severing relations to clear as strong arc happens. Such phenomenon induces an impact ambient noise and it gives the circumstance area resident or pedestrian the fear. Thus, it is necessary that we urgently need to control the ambient noise from the actual circumstances. In this study, we investigate the characteristic of an impact ambient noise associate with the melting state of the COS fuse and suggest the method to reduce the noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.97-102
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• 2004

The Characteristics of noise and vibration by heavy-weight floor impact sound was studied. Resonance frequency increased a little in structures that use damping material in living room and bedroom, and acceleration waves length that respond became short, and displayed aspect that oscillation level decreases. Result that measure sound pressure level, structure that compare and applies damping materials with structure that apply the resilient materials from 63Hz lower part that impact energy is concentrated in energy spectrum of heavy-weight floor impact sound displayed result that sound pressure, level decreases remarkably. Therefore, according to use of damping materials, confirmed reduction effect of heavy-weight floor impact sound.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.130-140
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• 2016

Floating floor is most commonly used at apartment houses in Korea for thermal insulation and reducing impact noise. But it in proven that the floating floor is not effective for reducing the floor impact noise in low frequency range. In most cases, impact sound pressure level under 63 Hz frequency band were actually increased by the resonance of resilient material, lightweight concrete and the finishing mortar installed on it. In this paper, an integrated floor system consist of 70 mm light weight concrete and 40 mm finishing mortar successively installed on the concrete slab was suggested to avoid the resonance. Integrated floor system increases total flexural stiffness and mass per unit area. The natural frequencies of first and second vibration mode were increased and acceleration response and floor impact sound level was decreased in all measurement range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.690-693
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• 2006

As the silence of vehicle is more important, noise reduction of tire is more required. Noise of tire is divided into structure home noise and air borne noise. Tire tread has the property such as Hardness. Pattern Noise is caused by changing of tread hardness. This property has influence on the mechanisms which are Block Impact & Stick-slip sound. In the study, we found that the effect of Hardness is related to more Stick-Slip than Impact.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.55-58
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• 2005

This study was Performed to grasp of the problem and improvement in traffic noise environmental impact assessment(EIA). National institute of environmental research(NIER) traffic noise prediction model is in general use in internal EIA. In this study, NIER noise prediction model need to improve in that the predicted results lower than the measured results. The other predict model(KLC KEI) is more accurate. Also the volume and speed of traffic is need to standardize in traffic noise prediction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1075-1075
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• 2006

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1062-1068
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• 2009

In this study, the impact force levels of bang machine and impact ball were measured, then the heavy-weight impact sounds generated by the bang machine and impact ball were investigated. It was found that the heavy-weight impact sources generated through modal excitation, and the impact force of the impact ball was similar to that of real impact source. The heavy-weight impact sounds were also measured in the real apartments with different slab thickness and floor structures. The results showed that the floor impact sound levels in terms of $L_{iFmax,AW}$, generated by impact ball sounds were reduced by using the resilient isolators. The frequency characteristics of heavy-weight impact sounds at 125 and 250 Hz were consistent with the characteristics of impact force spectrum. However, the difference between the impact sounds and the impact forces were found at 63 and 500 Hz due to the resonance of the floor structure and flanking noise, respectively.