• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.484-488
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• 2007

In this paper, the measurement system using the microphone array developed for analyzing cabin noise of the vehicle and its applications are discussed. The sensor is a three dimensional microphone array, the microphones and cameras are equipped on the rigid sphere. The cameras are used for acoustic visualization. As applications, the experiments in both reverberation chamber and anechoic chamber are discussed. These results show that this system is very useful to evaluate or improve the vehicle sound insulation performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.421-424
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• 2000

This paper investigates the characteristics of analytical models in prediction of sound transmission loss for the multi-layered panels with high density mineral wools. The results show that the sandwich model is more adequate to account for sound insulation performance of those panels than the poro-elastic model. In order to improve STC(Sound Transmission Class), the effect of fiber directions of mineral wools is examined, analytically and experimentally. From the comparison of the measurements with the predictions, it is evident that the vertical fiber directions of mineral wools enhance STC value up to 6 dB, compared to that of the horizontal fiber directions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.567-574
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• 2011

Aluminum extruded panels are widely used instead of corrugated steel panels for weight reduction in high-speed trains. Of the layers in the train body, it makes the largest contribution to the sound insulation. However, compared with that of a flat panel with the same weight, the TL of the aluminum extruded panel is remarkably lower in the local resonance frequency band. We study aluminum extruded panels for next-generation 400-km/h trains. We investigate the problem of sound insulation and propose a practical method to improve the sound-insulation performance. The local resonance frequency region is increased by a modification of the core structure, and urethane foam is placed in the core. The effect on the sound insulation is verified by experiments. Finally, the improvement for the entire sound-transmission loss is estimated for the layered floor panels of express trains.

• Journal of the Korean housing association
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• v.17 no.5
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• pp.47-54
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• 2006

This study aims to evaluate the sound insulation performance of Korean traditional paper(Hanji) windows as a material of environmental friendly building. Six types of traditional windows with 4 types of traditional window positions, were installed in l/2.5 scale model house. And then according to KS F 2235, comparative sound level differences between outdoor and indoor were measured. The main results are as follows; 1) TL(Transmission Loss) of Korean traditional paper windows, which cover one eighth of total balcony window, are ranged from 15 to 19 dB(A) in the living room and from 8 to 11 dB(A) in the balcony space. 2) TL of Korean traditional paper windows, which cover one fourth of total balcony window, are ranged from 10 to 19 dB(A) in the living room and from 8 to 10 dB(A) in the balcony space. 3) TL of Korean traditional windows with one side-one layer paper is ranged from 10 to 21 dB(A) and two side-one layer paper is 15 to 23 dB(A) and two side-two layer paper is 19 to 23 dB(A) respectively.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.182-187
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• 2002

Since most of main noise sources of the railroad vehicle are transmitted to the passenger's ear through the vibration of the panel, the insulation performance of the panels should be high enough to protect the passengers from the noisy environment. Specifically, the composite materials which are generally used for reducing the weight of the vehicle compartment have the low insulation performance, noise control actions should be taken appropriately by considering the insulation performance of the panels. In this study, the insulation performances of the inner/outer panels were evaluated and the contribution of the aluminum door was estimated compared to the composite panels. The results can furnish an indepth understanding of the insulation characteristics of the panel of railroad vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.101-104
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• 2005

This study presents experimental results from the performance test of a scaled reverberation chamber for measurement of sound insulation of panels. Experimental investigations were conducted in various parameters such as tunneling effect source locations, and maximum sound transmission loss. It is evident that the tunneling effect which means the variation with specimen location on the test frame gives rise to more than 3 dB deviation. One of the objective of this study that compares measured results between a real reverberation chamber and a simplified test apparatus, by using a specimen of a sandwich panel. It shows qualitatively resonable agreement from which one can find a potential to provide a design tool.

• Journal of the Korean housing association
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• v.16 no.5
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• pp.91-98
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• 2005

The purpose of this study is to analysis of propagation characteristics for floor impact noise in attendance upon investigating standard of insulation performance, measurement and evaluation, understanding characteristics of a measuring factor for floor impact noise in apartment houses. Four cases which was before occupied apartment in Daegu was selected for experiment. Floor impact noise of measurement and evaluation method which are specified in the Korea Standard 2810-1, 2810-2, 2863-1 and 2863-2 was selected for this study. As the result of this study, 1) Especially, there is not a difference for apartment size, but the apartment of 40py type is lower than 30py's about $1\~2\;dB$ for light-weighted and heavy weighted impact sound. 2) The floor impact sound insulation performance is similar about measurement location of the same floor structure. 3) The floor impact sound insulation performance is not a difference about the slab area.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.141-148
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• 2006

Korean traditional houses have been evolved and developed in many years, adopting the natural environment to control exterior conditions. These control method are various Passive system of using natural materials, considering micro climate, building lay out, and these system are much natural and ecological to make the comfortable indoor climate than active systems of the present houses. This study aims to analyzed the acoustical characteristics of Korean traditional houses varied with lay out and floor plan to reflect the way of control for environmental condition. The reverberation time and level difference between rooms of the main living room and other main floored room, master room and kitchen are measured in each houses. As a result, the reverberation time of Korean traditional rooms are below 0.6 second, and the sound insulation performance of Korean traditional door are mostly very low grade with D-15. The level difference between rooms are low grade not to meet minimum class except between main living room and master room away from main living building. These above results show that our traditional house are much more emphasized seeking visual privacy of rooms than aural privacy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.177-182
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• 2000

This study aims to provide an effective method to reduce construction noise generated by breakers. To reduce the breaker's noise level, a sound encloser was developed; the sound insulation's performance was tested in the field. From the field test, the following results were obtained. The sound insertion loss was about 6.5dB(A), even though part of the sound encloser for the breaker was left unclosed. This is equal to the reduction value which can be obtained by using more expensive low noise breakers, proving that there are more effective measures for sound insulation at lower cost. The characteristic of frequency was evaluated to show an even reduction through all frequency bands, except 630Hz.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.834-840
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• 2010

The Sound reduction indices(SRIs) of interior door with 13 different size apertures are measured in acoustic chamber. Also, as a theoretical approach, the SRIs are estimated using Gomperts' theory. In this study, the aperture of interior door is focused on the lower part of door leaf which is well known as a main cause to deteriorate the sound insulation performance of door. The results show that the SRI of door strongly depends on the aperture width and the dip in the measured sound reduction index curve by the resonance effect within aperture is observed at high-frequency. On the whole, the values calculated by theory are in good agreement with the measured values including the position of resonance dip. The average difference between the measured and the calculated values is 0.9 dB for 13 doors with different size aperture in terms of the weighted SRI.