• KIEAE Journal
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• v.11 no.1
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• pp.3-8
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• 2011

Sound absorbing materials used for lightweight panels and interior material are mainly made of fibroid material such as glass wool or rock wool. However these fiber type sound absorbing materials have some problems such that sound absorption could be decreased as time goes by because of durability. In addition, dust scattering from fiber type material can cause another problem in health. In this point of view, this study aims to develop environment friendly sound absorbing material using Hwangto(so called loess or yellow soil), a traditional housing material. Hwangto is natural housing material in Korea and generally known for improving indoor air quality. Hwangto panel is made to construct on the floor, wall and ceiling, and expected that there is not enough absorption. Present study tried to develop environment friendly sound absorbing material that has high sound absorption performance with good environment performance in terms of air quality. Pore rate was designed to maximize the absorption in the specific frequency bands, and two kinds of backing space were applied in order to see the effect of backing space. As a result peak frequency that has maximum absorption is going high as the pore rate is increased. The backing space provides more absorption and makes the peak frequency down to low.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.132-133
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• 2010

• The Journal of the Acoustical Society of Korea
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• v.18 no.4
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• pp.65-70
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• 1999

To examine the space variances of the sound pressure level for five different types (normal frequency spacing) of reverberation rooms, simulations were conducted using the Finite Element Method. In case of infinite surface impedance, nonrectangular reverberation rooms showed small Standard Deviations across the band of frequency, and in case of finite surface impedance, ideal rectangular reverberation rooms showed the similar results as those in irregular shaped reverberation rooms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.879-884
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• 2003

This paper is to experimentally investigate the effect of the through-flow and grazing-flow on the absorption performance of a perforated plate system. The experiment is performed through the systematic change of the through-flow velocity, grazing-flow velocity, incident sound pressure level, and the geometrical parameters such as the porosity and hole diameter. From the experimental results, it is found that for the nonlinear relationship between the acoustic resistance and incident sound pressure level there is no influence of the through-flow on the absorption performance, but fur the linear relationship between them there is a strong dependence of the absorption performance on the through-flow velocity. It is also shown that the absorption performance is controllable by changing the porosity and hole-diameter in size.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.309-311
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• 2005

본 연구에서는 폐유리를 별도의 전처리 과정 없이 최적조건에서 발포된 발포유리의 pH, 밀도, 열전도율, 압축강도 그리고 흡음율을 측정하였다. 최적조건에서의 온도변화에 따른 물성특성을 측정한 결과, 온도가 높아짐에 따라 밀도는 감소하였는데 이는 융용상 형성이 증가하고 표면에 형성된 응용상의 발포된 기체를 내부에 포집하여 큰 기공을 형성하여 밀도가 감소하는 것으로 사료된다. 또한 온도가 높아짐에 따라 pore size가 커지고, 압축강도가 감소하는 경향을 보인다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.163-167
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• 2003

This paper is to experimentally investigate the effect of the through-flow on the absorption performance of a perforated plate system. The experiment is performed through the systematic change of the through-flow velocity, incident sound pressure level, and the geometrical parameters such as the porosity and hole diameter. From the experimental results, it is found that fur the nonlinear relationship between the acoustic resistance and incident sound pressure level there is no influence of the through-flow on the absorption performance, but for the linear relationship between them there is a strong dependence of the absorption performance on the through-flow velocity. It is also shown that the absorption performance is controllable by changing the porosity and hole-diameter in size.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1036-1039
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• 2004

This paper is to experimentally study on the sound absorption of a membrane resonance type system. Membrane resonance type system improves the weak point of a perforated plate system. The experimental results for a membrane resonance type system are explained in comparison with those of a perforated plate system. From the experimental results, it is found that there is an influence of the membrane on the absorption performance. The sound absorbing performances of a membrane resonance system are similar to those of a perforated plate system.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.25-29
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• 1994

The effect of moisture content on acoustic absorption coefficient and impedance of the woods of Pinus densiflora, Chamaecyparis pisifela, Cryptomeria japonica, Abies koreana, Melia azedarch var. japonica, Shorea bracteolata and Shorea acuminata was investigated by standing wave method. The results obtained are summarized as follows: The acoustic absorption coefficient increased with increasing moisture content, but acoustic impedance decreased with increasing moisture content.

• KIEAE Journal
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• v.8 no.5
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• pp.3-10
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• 2008

The Korean traditional architecture has developed by adapting to the natural environment, and has successfully created a comfortable indoor settings by using the surrounding natural resources. This is reflected in the building layout, space design and even materials. Our traditional wooden windows adjusting ambient temperature and humidity have both the functions of window and door, although they are clearly divided in the West. The opening and closing method of our traditional windows is similar and their dimensions are shown not to be standardized but diverse in terms of the characteristic of wooden furniture and that of components placed between columns. Thus this study aims to research the sound insulation and absorption performance of traditional windows to be varied with thickness, finishing method of window paper and thickness of air layer. Despite increase of the thickness of window paper, sound absorption was reduced, and the same result was shown when both sides of the structure were finished with thick window paper. The sound insulation performance of the windows could be evaluated to be inappropriate with $R_w$ 0 ~ $R_w$ 14.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.62-66
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• 2006

In this work, the properties of environmentally friendly functional panel made from waste aluminum were investigated. Product quality enhancement was pursued through an improved viscosity process, a mixing process by agitating, a foaming process, a cooling process, and a color addition process. An acoustic transmission attenuation test, a sound adsorption rate measurement test, and a foaming condition and scrap mixing test were implemented. As a result, the functional panel made from waste aluminum was ultra lightweight and had excellent properties such as soundproof, sound interception, and shielding harmful electromagnetic waves. Also, the functional panel showed low thermal conductivity (about 2.2 kcal/mh) and excellent heat-insulating property.