• 한국재료학회지
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• 제4권1호
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• pp.3-8
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• 1994

최근 중요하게 된 진동 흡수를 위해서 $BaTiO_{3}$ 세라믹의 흡진 특성을 측정하고 미세구조와의 연관을 조사했다.$BaTiO_{3}$ 세라믹은 비교적 물리적 화학적으로 안정하여 좋은 흡진재로 기대된다.BaTiO$_{3}$ 세라믹은 흡진 특성을 강화시키기 위해서 섬유상 분말을 소결하여 만들었다. KDC법으로 직경이 0.2$\mu\textrm{m}$, 1.2$\mu\textrm{m}$, 2.0$\mu\textrm{m}$인 각각 다른 섬유상 $K_2Ti_4O_9$을 만들고 이온교환해서 섬유상 $BaTiO_{3}$ 을 만들었다. 면상으로 배향시킨 소결체의 흡진 특성과 전기적 물성을 조사하여 미세구조와 의 관계를 밝혔다. 소결체의 입경과 등가회로, 전기기계합계수($K_{t}$), 발생 전압(V)을 조사한 결과, 사용한 섬유의 직경이 클수록 소결체의 입경은 작아졌다. 따라서 입계가 많아졌다. 흡진 특성은 입계가 많을수록 커진다. 즉 입계의 내무마찰이 클수록 흡진률은 커지며 이때의 내부마찰은 등가회로를 조사함으로써 확인되었다.

• 한국소음진동공학회논문집
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• 제27권2호
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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.

• 한국소음진동공학회논문집
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• 제22권2호
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• pp.103-114
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• 2012

Nowadays membrane material is widely used for large indoor spaces and long spaces such as traditional market. Thermal insulation and sound field control performance is considered as a main properties for design of such buildings. In this paper sound absorption and thermal insulation properties of membrane material was investigated. Firstly, normal incidence sound absorption coefficient of 10 kinds of glass wool textiles showed that sound absorption coefficient was increased in proportion of thickness and surface density of textile. Sound absorption coefficient of 4 kinds of sound absorptive inner membrane with outer membrane was tested in the reverberation chamber. Sound absorption coefficient of mid frequency range was about 0.4 ~ 0.6. Also, sound absorption coefficient was changed by the air space behind the membrane material. Secondly, sound field control performance was investigated using mock-up space. By the installation of sound absorption membrane material, reverberation time was decreased and speech intelligibility was increased. Finally, thermal resistance and room temperature in two kinds of mock-up rooms were tested, simultaneously. Results of thermal properties showed thermal insulation properties ware increased by adding inner membrane material underneath the outer membrane.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.964-968
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• 2007

A helmholtz resonator has been widely used for the purpose of suppressing low frequency noises propagated from various heat and fluid machineries. However, the resonator has demerits that the absorption bandwidth at resonance frequency is very small and a large cavity is necessary. In order to overcome these problems, in this paper, a resonator with perforated panels at the neck and/or in the cavity is proposed. The absorption performances of resonators are measured by two-microphone method and are estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients are agreed well with the corresponding values from the transfer matrix method. By introducing perforated panels at the neck of a resonator, it is shown that the absorption performances and bandwidth have a significant improvement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.886-889
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• 2002

흡음률을 평가하기 위한 연구로서 임피던스 튜브를 통한 수직입사 흡음률과 잔향실을 이용한 랜덤입사 흡음률에 대한 실험연구를 수행하였다. 한편 수직입사와 랜덤입사와의 상관관계를 실험 연구를 통하여 조사하였다. 이 상관관계는 주파수에 따라서 다르게 나타나고 있다. 저주파수 대역에서는 랜덤 입사가 수직입사 보다 크게 나타나고 있지만 고주파수에서는 수평입사 성분의 영향으로 랜덤입사에서는 감소하는 경향을 보이고 있다.

• 한국소음진동공학회논문집
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• 제16권7호
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• pp.683-689
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• 2006

The sound absorption materials have been used to enhance the performance of a noise barrier and improve the room acoustics. In this study, 6 products of sound absorption materials generally used in Korea were chosen, and their absorption performance was tested in various conditions, that is, it was measured while changing thickness, density and air-gap in their back, and measured with or without facing on their face.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.877-882
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• 2002

A new estimation model of predicting the sound absorption performance for multiple perforated plate sound absorbing system was developed using transfer matrix method. The proposed method was validated by comparing the calculated absorption coefficients of a single layer perforated plate with the values measured by the two-microphone impedance tube method far various porosity and cavity depth. The developed transfer matrix method was further applied to estimate the multiple layer perforated plates and it is shown that the estimated absorption coefficients generally agree well with the measured values.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1003-1008
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• 2005

The acoustic absorption of a multiple layer perforated plate system is very good near the resonance frequency region, while it has been regarded as a demerit that its frequency bandwidth is considerably narrow. In order to overcome such a demerit, the parallel perforated plates with different porosities are proposed. The sound absorption of such system composed of a parallel perforated plate is calculated by an equivalent electroatoustic circuit approach and validated by comparing the calculated absorption coefficients with those measured by the two-microphone impedance tube method. The sound absorptive characteristics and performance of parallel perforated plate systems are discussed from a standpoint of frequency bandwidth related with sound absorption.

• 한국소음진동공학회논문집
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• 제12권9호
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• pp.709-716
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• 2002

A practical method of predicting the sound absorption coefficient for multiple perforated-plate sound absorbing system was developed using transfer matrix method. The proposed method was validated by comparing the calculated absorption coefficients of a single layer perforated plate with the values measured by the two-microphone impedance tube method for various porosity and spacing of the perforated plate. The developed transfer matrix method was further applied to estimate the multiple layer perforated plates and it is shown that the estimated absorption coefficients agree well with the measured values.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.387-392
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• 2003

This study is put a focus on the identification of sound characteristics according to the interior configuration of sound absorption material and air gap. Noise barrier is general consists of front perforated panel, air layer, sound absorption material, air gap and back plate. Noise barrier is required to the NRC value of 0.7. The absorbing performance of the noise barrier relies on the opening ratio of the perforated panel and the efficiency of the absorbing material. This study has observed the effect of opening ratio and hole size, the increase of sound absorbing performance by the configurations of sound absorption material and air gap. New designed noise barrier is achieved the acoustical performance of 0.87 the measurement in a reveration room.