• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.760-765
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• 2013

Eco-friendly material applied to building would be one of the materials which is must developed for global environmental conservation and reduction of carbon dioxide. For development of eco-friendly material, a cellulose sound-absorbing material has been developed with waste paper through adjustment of various mix proportions. The developed cellulose sound-absorbing material has been tested for its acoustic properties such as acoustic absorptivity and dynamic elastic modulus. The absorptivity was evaluated by developing six samples and using impedance tube and reverberation chamber. As a result of the evaluation, 0.64(NRC) was secured in absorptivity and $4.7MN/m^3$ was indicated in dynamic elastic modulus. Also, for practical use of developed sound-absorbing material as inner heartwood in drywall, comparison test of sound reduction index was performed with existing glass wool sound-absorbing material and constructed drywall of gybsum board. The results have shown 55dB(Rw) of sound reduction index in glass-wool wall and 46dB(Rw) in cellulose.

• Journal of the Korean Wood Science and Technology
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• v.50 no.6
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• pp.404-413
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• 2022

This study aims to investigate the sound absorption ability of Acanthopanax senticosus wastes as an eco-friendly sound-absorbing material. The sound absorption coefficient was examined with different heights of A. senticosus wastes filling (40, 60, 80, and 100 mm) in impedance tubes. The sound absorption peaks shifted to a lower frequency as the height of A. senticosus wastes inside the tubes increased. The sound absorption ability at filling heights of 80 and 100 mm was obtained as 0.3M and 0.5M grades, respectively, based on KS F 3503. The results suggest that A. senticosus wastes exhibit good sound absorption ability and can therefore be used as an efficient, eco-friendly sound-absorbing material.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.870-873
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• 2003

This research is about the sound attenuation in the duct with lining sound absorbing material in it. Many previous researches assumed the property of lining material as locally-reacting. As the thickness of lining material thickens or the upper limit of the interested frequency range goes higher, there is a growing tendency for the experiment results to deviate from the theoretical results based on the locally reacting assumption. In this paper, the acoustic performance of the two-dimensional dissipative silencer with the propagation of sound in the absorbent was derived theoretically and calculated. The effect of increase of sound absorbing material is also considered. These results are compared from the previous results with using the locally-reacting property of sound absorbing material.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.331-339
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• 2016

To improve the acoustic performance of sound absorbing materials, the thickness of the material should be increased or the sound absorbing material having an irregular surface shape should be used. In this study, the acoustic characteristics and methods to improve the acoustic performance of a sound absorbing system equipped with double layered polyester sound absorbing materials were investigated. The numerical model was set up and the results obtained from the model were compared with the actual measurement data. And, strategies to improve the acoustic performance of sound absorbing systems with double layered sound absorbing materials made of polyester with different configuration were shown. So, this study is expected to be usefully used at sites that require high acoustic absorption performance with minimal installation thickness to reduce sounds reflection in narrow spaces such as interior of subway tunnels or in noise barriers installed adjacent to rails.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.139-144
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• 2015

Recently, to realize sound-absorbing structures, we have to insert sound-absorbing materials into wall. These shapes are taken limitations because sound-absorbing materials should be fixed. Therefore, the sound absorption is changed by environment that used the sound-absorbing materials. On the other hand, we will take same effect without sound-absorbing material, if we change the shape of wall to sound absorbing structure. If we use this sound absorbing structure, we can get benefits by removing limitation of materials. Therefore we suggest perforated plate for effective sound-absorbing structure. We confirmed the function of sound-absorption of this structure using equivalent property. Then, we found the similarity between perforated plate and resonator. Also, we verify these theories through computer simulation by FEM(Finite Element Method). Finally, we validated that perforated plate has function of sound absorption without sound-absorbing material. This perforated plate is used for sound-absorbing material of buildings and transportations such as vehicle, train etc. Also, these results could be further used basic tool for design of sound-absorption structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.575-580
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• 2013

This study focused on the identification of sound characteristics according to the configuration of sound absorption material and perforated panel dimensions. Noise barriers consist of front perforated panel, sound absorption material and back plate. Noise barriers' acoustic performance should be required to meet the NRC of 0.7. The absorbing performance of the noise barrier relies on the opening ratio of perforated panel and the efficiency of the absorbing material. This study try to find out the possibilities of applications to railway usage.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.76-81
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• 2021

A plastic noise barrier is a structure installed to minimize noise, and it is composed of the main plate, sound-absorbing plate, and sound-absorbing material. Plastic noise barrier structures have several advantages compared to other products, such as light weight, anticorrosion, durability, easy assembly, rapid construction, and low costs. In this study, the main and sound-absorbing plates were manufactured through extrusion molding, and the sound-absorbing plate was finished with a press to improve the conventional injection molding. Extrusion molding dies and punch dies were designed, and a profile extrusion-molding system was developed. Thus, inexpensive and efficient sound-absorbing and main plates can be produced, and the noise barrier structure can be assembled rapidly. Additionally, a noise barrier structure with extended service life and excellent quality can be constructed by creating uniform free space to accommodate increased temperatures after assembly and installation.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.23-28
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• 2011

This paper studied combustion characteristics of the building materials such as polyurethane-foam, sponge type sound-absorbing materials and styrofoam. To estimate of the combustion characteristics, we carried out combustion experiment of the building materials. And then to evaluate the suitability of the building materials, we measured heat release rate(HRR) and smoke density(Ds) of polyurethane-foam, sponge type sound-absorbing materials and styrofoam using by a cone-calorimeter. From the combustion experimental results, the general type sound-absorbing materials (GSAM) and styrofoam were rapid burned simultaneously with ignition and the incombustibility type sound-absorbing materials(ISAM) and polyurethane-foam had all gone out simultaneously with ignition. Measured results of HRR and Ds were not satisfied KS F ISO 5660-1 and IMO FTP Code, from the results, the polyurethane-foam, the sponge type sound-absorbing material and the styrofoam were ill-suited for using building interior materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.601-604
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• 2006

Recently the new inorganic sound-absorbing material manufacturing techniques have introduced. These mainly is plentifully used in the place where the noise damage becomes problem in life environment, partitioning of the apartment, the railroad and the express highway, school and the residential quarter neighboring area etc. While the sound-absorbing material has vast quantity of open pore, sound insulation material, used in the apartment and high building in order to prevent the sound between layers, has suitable quantity of closed pore. The fly ash is widely used in the cement materials and the concrete binder material. The bottom ash, however, is rarely used for the grain size is big and multiform with unburning carbon ingredient. In this paper, the practical field tests and the results on the sound reduction properties of formed concrete using bottom ash are described.

• Journal of KSNVE
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• v.10 no.6
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• pp.963-970
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• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14,500 rpm. Due to the high rpm of the impeller, the noise of chiller males one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the numerical study, it is also shown that appropriate use of sound absorbing material at this region makes 8dB reduction of the highest noise level.