• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.475-484
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• 2012

The purpose of this study is to help to prevent daily noises by measuring the noise absorption coefficient of the non-woven fabrics and wallpapers which are commonly used in lining and noise absorption coefficient of lining curtain. Seven types of fiber materials for the interior decoration, one non-woven fabric for the wallpaper linings, and two types of textiles for curtain linings are used as the experimental materials in this study. The noise absorption coefficient of the noise absorbents were measured by using impedance tube. And the thermal transmittance were measured by using thermal transmittance tester. The results of this study are as follows; Observing the noise absorption efficiency of each experimental materials, the combination of fiber materials and linings, the noise absorption efficiency of cotton, polyester and silk were similar and for the experimental materials of flax, rayon, acrylic and nylon were resulted the similar noise absorption efficiency. The result of combination of fiber material and black fabric was highest among the combined linings. For the combination of fiber material and non-woven fabric, double layers of non-woven fabric resulted slightly higher noise absorption coefficient result than single layer of non-woven fabric. The thermal transmittance and the sound absorbents of experimental materials were affected by the thickness, density and layer of air of the experimental materials.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.243-250
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• 2017

In this study, single number rating methods of sound absorption coefficients are discussed. After that the sound absorption performance of noise barriers which are classified by Korea Standard are analyzed according to several standards. The existing rating methods such as NRC (noise reduction coefficient), SAA (sound absorption average) or ${\alpha}_w$ (weighted sound absorption coefficient) from ASTM C423, KS F 3505 and ISO 11654 are introduced. The sound absorption performance of noise barrier is evaluated to compare NRC and ${\alpha}_w$ value. When the value is over 0.6 there are large variance between NRC and ${\alpha}_w$ value. As results, it is needed to unify single number rating methods of sound absorption coefficients for Korean standards on sound absorbing materials.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.5
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• pp.83-88
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• 2001

The sound absorption coefficient of glass wool (bulk density of 48 kg/m:1 and 32 kg/m7) was measured by reverberation room method as varying their cross-sectional area. The results show that the absorption is larger for smaller samples because of edge effect. The absorption coefficient with two different kinds of sources. 1/.7-octave band and while noise, gives similar values.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.643-649
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• 1998

This paper is to compare the absorption coefficient with normal incidence waves and it with diffuse incidence waves of glass wool which the most used absorption material and multi layer fiber. The absorption coefficient with normal incidence waves is calculated by surface impedance that measured by using an acoustic tube. Based on this data, the absorption. coefficient with diffuse incidence waves is predicted and is compared with measured the absorption coefficient in reverberation room.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.185-190
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• 2000

The sound absorption coefficient of glass wool (bulk density of 48 kg/$m^3$ and 32 kg/$m^3$) was measured by reverberation room method as varying their cross-sectional area. The results show that the absorption is larger for smaller samples because of edge effect. The absorption coefficient with two different kinds of sources, 1/3-octave band and white noise, gives similar values.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.270-275
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• 2009

Sound absorption characteristics of membrane system which are used in stadiums and arenas were investigated. Theoretical studies on acoustic properties of single and double leaf permeable membrane conducted. Also, experimental studies on sound absorption characteristics of combined membrane system that is composed of outer and inner membrane material were conducted. In this study, sound absorption characteristics of each membrane were investigated by experiments in reverberation chamber. 4 types of permeable membranes and a non-permeable membrane were used for experiments. Air space behind membrane material and tension on the membrane was varied. Sound absorption performance of permeable membrane materials was confirmed. As increasing air space behind the membrane material, sound absorption coefficient was increased. In a resonance absorption frequency band sound absorption coefficient varied more dramatically. Sound absorption characteristics were flat in mid and high frequency range and sound absorption coefficient was from 0,3 to 0,5. Also sound absorption coefficient was increased by the increment of surface density and air permeability of membrane. However, over the certain value of air permeability, sound absorption coefficient was decreased. These results can be used as design factors and method for the room acoustic design of dome-stadiums and large free-form buildings.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.382-385
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• 2009

Efforts to reduce noise in industrial application fields, such as automobiles, aircrafts, and plants have been gaining considerable attention while a sound proof wall to protect people from the noise has been intensively investigated by many researchers. In this study, our research group suggested creating a new sound proof wall composed of scrap aluminum chips and perforated plates in a commercial polyester sound proof wall, which was then successfully fabricated. This wall's sound absorption characteristics were measured by an impedance tube method. The sound absorption property was evaluated by measuring the Noise Reduction Coefficient (NRC) to the standard, ASTM C 423-90a. The noise reduction coefficient of the sound proof wall composed of 3.5 vol.% and 7.5 vol.% of scrap aluminum chips relatively increased to 5% and 8% compared to the commercial polyester sound proof wall. The scrap aluminum perforated plate also relatively increased to 13% compared to the commercial polyester sound proof wall.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.50-56
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• 2004

This study was conducted to investigate the performance of sound absorption type-noise barriers manufactured with a combination of wood particles used for particleboard, recycled waste newspaper, and cement. An average density of wood-combined cement board was in the range from 0.83 to 0.96 g/cm³, showing relatively low-density board. Regardless of types of cement bonded board or wooden board, the board with concave holes(凹)-formed surfaces showed greater sound absorption coefficient compared to those of flat surface boards. The board density was not related with those coefficients. Accordingly, it was concluded that concave or deep corrugated surface structure has played an important role in sound absorption for the application of sound absorption type-noise barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.683-686
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• 2007

This paper investigates acoustical characteristics of open-type ceilings using 1:25 scale model. The field survey in the existing 15 halls was carried out to figure out the ceiling structure. The components of the open-type ceiling were mainly steel truss structures, duct, catwalk and finishing surfaces. In order to investigate the absorption characteristics of the equipped ceiling, the absorption coefficient measurements were made using 1:25 reverberation chamber based on ISO 354. Results showed that the absorption coefficient of the empty ceiling structure (6m-height) with 50%-perforated covering plate was 0.2-0.3 at above 500 Hz. When steel structure was added inside the empty ceiling, absorption coefficient increased by 0.16 at 250-1kHz. Adding catwalk did not increase the absorption, but adding duct increased the absorption at 1-2kHz. NRC of the equipped ceiling was 0.39, and the absorption characteristics were mainly found at high frequencies. In addition, the opening size of the covering plate did not change the absorption coefficient of the equipped ceiling meaningfully.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.983-986
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• 2007

The absorption power of a surface depends on the surface irregularity which has been known as an important factor in determining scattering coefficient. This study investigates the effect of increase in surface area on the absorption and scattering coefficients of a diffuse surface. The surface irregularity or surface pattern can be compared to the wavelengths and the random-incidence scattering coefficient of surface is measured by ISO 17497-1. The scattering coefficients of increasing the surface area in linear pattern of v-cut groove on rubber plate were measured in 1:10 scale model reverberation chamber. It is found that the scattering and absorption coefficients increase with increasing surface area. At 60% of increased surface area the spacing between the hemisphere diffuser and the v-cut groove acts similar with results of absorption coefficient. The results show that absorption coefficient depends on surface area and the spacing where as scattering coefficient depends on surface area and texture.