Sound Absorption Capability of Medicine Herb Residues Mat

Eun-Suk Jang,Nam-Ho Lee,Chun-Won Kang 한국펄프·종이공학회 2023 펄프.종이기술 Vol.55 No.4

This study investigated the sound-absorbing properties of herbal medicine waste (HMW) as a promising eco-friendly material for sound absorption. The authors examined the sound absorption coefficient by filling impedance tubes with varying heights of HMW (4 cm, 6 cm, 8 cm, and 10 cm). The results revealed that at a filling height of 4 cm, the optimal sound absorption frequency was found to be 1416 Hz, with a sound absorption coefficient of 0.999. Similarly, at a filling height of 12 cm, the optimal sound absorption coefficient was 0.965 at 456 Hz. It was observed that the sound-absorbing performance at lower frequencies improved as the thickness of the sound-absorbing material increased. Based on the standards established in KS F 3503, HMW would receive a sound absorption grade of 0.5M to 0.7M, depending on the filling height. In conclusion, HMW showed excellent potential as a sound-absorbing material, and the results of our testing showed that it can be used as an alternative to synthetic fibers.

냉장고 기계실의 고주파 소음 특성 분석을 통한 음질 개선

장준영,김태훈,탁언수,정의봉,안세진 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.5

This paper provides an analysis of the characteristics of the noise of components that affect the sound quality of oil-less refrigerators and suggests ways to effectively improve the sound quality. As the sound quality of refrigerators is determined by the characteristics of the various components and the path through which the noise is transferred, it is necessary to first analyze the characteristics of the noise generated by the components. Therefore, after measuring the noise of each part, we conducted a contribution analysis of the sound quality of each noise source. As a result, the oil-less compressor was found to be the dominant part of the sound quality of the refrigerator, while the high-frequency noise of the compressor is the main cause of poor sound quality. Then, to improve the sound quality by reducing the high-frequency noise of the compressor, we changed the transfer path of the noise using sound-absorbing and -insulating material and predicted the effect of the sound quality through a pressure transmissibility test. As a result of verification from actual operation, the sound quality of the refrigerator was improved most by the reduction of the sharpness and criteria of declination when the absorbent was attached to the surrounding walls of the compressor. Finally, the overall SPL decreased by 2.95dBA, and the sound quality score was improved by 1.83.

Enhancement of Sound Clarity of Classrooms Using Sound Diffusers and Panel Absorbers

Shin, Sang-Bong,Haan, Chan-Hoon The Acoustical Society of Korea 2009 韓國音響學會誌 Vol.28 No.e2

The present study aims to investigate the effects of sound diffusers and absorbers on the sound clarity in classrooms. In order to do this, computer simulations were carried out to find the effective area of treatment which could enhance the sound clarity in the room. Acoustic measurements were undertaken in a lecture room with several conditions changing the surface of walls and ceilings with diffusers and absorbers. Diffusion and absorption treatments were applied to the side walls, rear wall and the ceiling of the classroom. SPL, RT, D50, RASTI were measured at 9 measurement points with one sound source and MLS was used as the sound source signal. The results show that higher sound clarity was obtained when diffusers were applied to rear walls and ceiling rather than side walls. Also, it was confirmed that absorption increased sound clarity more effectively with smaller amount in comparison with diffusers. It was also concluded that the effects of sound diffusers and absorbers on the sound clarity could be obtained distinctly at the rear area of the classroom.

Membrane구조를 갖는 섬유 집합체형 흡음재의 흡음 인자 결정에 관한 연구

장효준,전두환 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.4

Basic mechanism of sound absorption in various sound absorbing materials is generally explained by the conversion of sound energy into heat energy. The important element governing the conversion from sound into heat depends on the material characteristics. Three types, such as porous, resonance and panel types, generally classify the geometrical structure of sound absorbers. These three types of sound absorbing materials demonstrate different sound absorption characteristics. In this study, for the absorption of the specific sound frequency, various parameters are investigated experimentally using the impedance tube method. The models used in the experiment are porous and panel type absorbers. The porous type absorber generally has the ability of sound absorption at the high frequency range and the panel type absorber has the capability of sound absorption of the specific sound frequency. The sound absorption characteristics of the panel type absorber are described in phenomenon related to the sound absorption characteristics of porous type products. Detail experiments are carried out to clarify the parameters governing the acoustic performance with different fabrics.

재생 자원의 흡음특성에 관한 연구 : 폐지와 담배필터를 중심으로 Based on used Paper and Cigarette Filters

최창하,조해용,이주민 한국환경과학회 2001 한국환경과학회지 Vol.10 No.1

In this study, development of new sound absorbent which is safety, economical and efficient with using recycled materials is tried for substitution of commercial sound absorbent. The sound absorbents, used in this investigation, were made of used paper or filters of cigarette butts. With the variation of the material densities,, sound absorptions of materials were measured. The impedance tube method is used for measuring sound absorption coefficient of the new sound absorbent materials. The measured frequency range was 250㎐ to 4000㎐ in 1/3 octave band . The sound absorption coefficient of the commercial materials and that of the materials synthesized in the our laboratory show almost same value.

메쉬 직물의 밀도 및 위치변화에 따른 흡음특성

이경민,전두환,전상후,Lee, Kyoung Min,Chun, Du Hwan,Chun, Sang Hoo 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.3

Sound absorbing materials are generally categorized as porous-type absorbers and panel-type absorbers. In addition, their absorbing mechanism is typically described as a conversion of sound energy into heat energy through the dynamic behavior of the material. Thus one of the important parameters influencing the sound absorption characteristics is the density of the material. This study investigated the sound absorption characteristics of a mesh fabric based on the mesh density and fabric layering structure. Four different mesh densities (130, 180, 200, and 230 T) combined with five different layering structures were investigated to help understand the mechanism and effect of the sound absorption characteristics. The results indicate that a panel-type absorber has better sound absorption characteristics within a lower frequency range, whereas a porous-type absorber performs better at a higher frequency. In addition, the increased fabric density of the mesh fabric shows a better performance in terms of sound absorption. An empirical equation between the sound absorption coefficient and the fabric density was also derived for further design applications.

흡차음재의 특성 변화에 따른 차량 음질의 영향 평가

이건희(Kunhee Lee),신태진(Taejin Shin),이상권(Sangkwon Lee),김근영(Keunyoung Kim) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5

These days, drivers are not satisfied with simply being the cabin noise reduced, but demand to hear better sound in the cabin. Therefore, Automobile companies are conducting a lot of research in order to reduce the noise by considering the feelings of the drivers. In this study, we have investigated the relationship between sound-absorbing materials and sound quality based on ray acoustics and signal processing. First, the impulse response functions from engine to dash and from dash to driver’s position are calculated using ray tracing method. Second, two impulse response functions are convoluted by engine noise signal to yield the cabin noise. The cabin noise are used for the calculation of sound metric and the subjective test. The correlation between sound metric and subjective test are used and estimated for the production of sound quality index in accordance with sound-absorbing materials. The experimental method is also performed for the validation of index. The index will contribute to saving test time and developing a good performance sound-absorbing material.

Investigation of Sound Absorption Ability of Acanthopanax senticosus Wastes

장은석 한국목재공학회 2022 목재공학 Vol.50 No.6

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.

스펀지형 흡음재의 연소특성에 관한 연구

송재용,사승훈,남정우,김진표,박종택,이두형 한국화재소방학회 2011 한국화재소방학회논문지 Vol.25 No.3

This paper studied combustion characteristics of the sponge type sound-absorbing materials extensively used on building interior. To estimate of the combustion characteristics, we carried out combustion experiment of general type and incombustibility type sound-absorbing materials. And then to evaluate the suitability of the sponge type sound-absorbing materials, we measured heat release rate (HRR) and smoke density (Ds) of the sound-absorbing materials using by a cone-calorimeter. From the combustion experimental results, general type sound-absorbing materials were rapid burned simultaneously with ignition and the incombustibility type sound-absorbing materials had all gone out simultaneously with ignition. Measured results of HRR and Ds were not satisfied KS F ISO 5660-1and IMO FTP Code, form the results, the sponge type sound-absorbing materials were ill-suited for using building interior. 본 논문은 건축물 내부 마감 재료로 사용되는 스펀지형 흡음재의 연소특성에 관하여 연구하였다. 연소특성 평가를 위하여 일반 재질 및 난연 재질의 스펀지형 흡음재를 대상으로 연소실험을 수행하였으며, 건축용 내부 마감 재료 사용의 적합성 평가를 위하여 콘칼로리미터법을 이용한 열방출률 및 연기밀도를 측정 분석하였다. 연소특성 실험 결과, 일반 재질의 흡음재는 착화와 동시에 급속히 연소되는 특성을 나타내었으며, 난연 재질의 흡음재는 착화와 동시에 소화되는 특성을 나타내었다. 그러나 난연 재질의 흡음재에착화시간을 길게 하는 경우, 연소가 진행되는 것으로 평가되었다. 열방출률 및 연기밀도는 한국산업규격KS F ISO 5660-1 및 국제해사기구의 FTP Code를 만족하지 못하는 것으로 평가되었으며, 이러한 결과로 볼 때, 스펀지형 흡음재는 건축용 내부 마감 재료로 사용하기 부적합한 것으로 판단된다.

Peanut Shells as an Environmentally Beneficial Sound-Absorbing Material

장은석 한국목재공학회 2022 목재공학 Vol.50 No.3

This study investigated the prospect of using peanut shells as an alternative and green sound-absorbing material. The sound-absorption coefficients were determined after filling impedance tubes of 30, 60, and 90 mm in height with peanut shells. The sound-absorption ability increased as the filling height increased, showing noise reduction coefficient (NRCs) of 0.23, 0.43, and 0.54 for the 30-, 60-, and 90-mm heights, respectively. In addition, for sounds greater than 2,000 Hz, the average sound-absorption coefficient of peanut shells in the 60- and 90-mm heights was 0.9. In summary, peanut shells were found to have good sound-absorption properties comparable to or better than those of bamboo, sisal, jute, and wool, and this research suggests that peanut shells may be useful as an environmentally friendly sound-absorbing material.