• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1097-1102
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• 2009

In a railway vehicle, corrugated steel panel is widely used for the floor panel because of its high bending stiffness and light weight. However, this panel shows lower sound insulation performance than that of the plate with the same weight. Especially, in a particular frequency band, transmission loss (TL) rapidly decreases and it results in the deterioration of TL of the overall floor panel. This study identifies that the remarkable drop in TL is caused from the local resonance of the periodic corrugated structure. This study shows that the frequency band of the TL drop can be controlled by the proper design of the corrugated structure. In addition, improvement effect of TL by attaching foam and glass wool is estimated by experiment. The purpose of the study is to provide the practical information for the improvement of the sound insulation performance of the corrugated steel.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.646-650
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• 2001

In this paper, it is presented that the effect of air gap insertion in testing the transmission loss of sound barrier using structural vibration system. In this study, we use the APAMAT based on the structure-borne-noise. The measured results show that air gap insertion improves transmission loss as results of test based on the air-borne-noise. The measured results are compared with the predicted transmission loss using the transfer matrix method. The predicted results were found to be in reasonable agreement with measured results.

• 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.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2002.11a
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• pp.237-332
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• 2002

We constructed ceiling structure and floor structure for elevation of sound insulation performance of concrete slab of apartment house. And, we wished to measure heavy floor impact sound level and light floor impact sound level of these structure. As the result, light floor impact sound level interception performance of concrete slab was measured by thing that construction work of gypsum baud is important. Heavy floor impact sound level interception performance was measured by thing that it is effective that construct to thickness about 30 millimeters on concrete Slav. It was measured effectively that heavy floor impact sound level interception performance constructs rubber chip to thickness about 30 millimeters on concrete Slav.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1109-1113
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• 2001

Interior parts of a vehicle are getting important to reduce interior noise of car. Therefore, prior analysis of cabin noise related with interior parts are necessary at first design stage. Recently, Statistical Energy Analysis(SEA) has been suggested as a possible way for meddle of high frequency range analysis with interior parts. This article introduces an example of the application of SEA to predict air born noise of cabin of car.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.222-226
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• 1997

The reproducibility of measured level is a prior condition for the reliable assessment of the sound insulation performance. To review the reproducibility of impact sound level, 20 floors were selected in highrise apartment house, and then impact sound levels of two kinds of typical floors were measured with 10 times in each receiving point. The impact sound insulation class values were derived with a standard tapping machine and bang machine. Inspection of the result showed that smaller scale of the room caused to lower the reproducibility and that the higher values of standard deviation in lower frequency caused to deteriorate the reliability of assesment. Thus to enhance the reproducibility of the impact sound insulation class, greater allowable deviation of measured level is required in lower frequency than in higher one.

• Journal of KSNVE
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• v.10 no.1
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• pp.82-96
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• 2000

The purpose of this study is to figure out the relationship between the mini-laboratory and the reverberation room for the domestic floor structures which are practically constructed in apartment houses. For this purpose, seven specimen which were varied in structures and thicknesses were tested in Chonnam National University reverberation room and in the artificial mini-laboratory which is the $\farc{1}{3}$ scale model of the former. From the result of this study, it was proved that there is a good correlation between the mini-laboratory and the reverberation room for the apartment floor structures as well as floorcovering PVC. The result of this study could save the labor and the time, etc.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.336-339
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• 2000

Revision of KS, Korean Standards, is currently actively discussed. It is just the time for a new world class standards under the new system with WTO, World Trade Organization. This paper is a part of "Researchs on the Standards in the Building Acoustic Field", as one of KS revision projects. The aim of this study is to define the requirements of laboratory test facilities with suppressed flanking transmission. In the former KS, there is no items matched with this purpose. Therefore comparing several results with different measuring conditions of a laboratory and results between different laboratories was impossible. On these basis, a new part of KS is proposed, and some problems remained and further discussions in the proposed draft are described in this study.

• 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 for Noise and Vibration Engineering
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• v.20 no.10
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• pp.931-939
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• 2010

A dash panel plays an important role to protect noise as well as heat. Meanwhile, it is also the most important path that transfers energy to the interior cavity, so that some of noises are transferred via air and its structural vibration becomes a major issue. From the viewpoint of NVH performance, simplified structures analogues to the dash wall are dealt with. Stiffeners, damping sheets and sound packages attached to a flat panel are taken into account as design variables. Structural radiation characteristics(thus, structure borne) such as radiation efficiency and radiation power are mainly discussed. For the case when an excitation is applied on a frame that surrounds the panel, it is shown that the radiation efficiency increases by attaching a stiffener to the panel, which is similarly found from the case when a panel is directly excited. It seems more effective to attach damping sheets along the boundary area of the panel rather than its middle area. The radiation efficiency of sound packages may make a dominant contribution to transmission loss as well as sound radiation. Experimental work was carried out to verify the results based on the simulation study.