• Title, Summary, Keyword: Sound characteristics

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A Study on the Reduction of the Lightweight Impact Sound Level by Floor Coverings (바닥마감재가 경량충격음 저감량 평가에 미치는 영향)

  • 정진연;이성호;정갑철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.137-142
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    • 2004
  • The aim of this study is to investigate the characteristics and quantity of the noise reduction by floor coverings. The characteristics on the reduction of the lightweight impact sound level by floor coverings is as follows. The insulation level attained by floor coverings tends to be smaller in actual buildings than in public laboratories. The reduction of the impact sound level to the tape is similar to the method of adhesives. For this reason, the reduction of impact sound level by floor coverings in public laboratories can be utilized to tape. And the reduction of impact sound level by floor coverings is not influenced by the size of specimen except the specific frequency.

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An Evaluation on the Sound Insulation Performance of Drywall for High-Rise Buildings (초고층 건물에 적용 가능한 건식벽체의 차음성능 평가)

  • Lee, Sang-Woo;Yoo, Ho-Chun;Lee, Su-Yeal;Jung, Gap-Chul;Jung, Young-Min
    • KIEAE Journal
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    • v.7 no.2
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    • pp.3-8
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    • 2007
  • Recently, the structural system of public residential buildings has been changed from the reinforced concrete (RC) wall system to the (PC) wall and moment resisting systems. Thus, it is important to develop the suitable wall system in accordance with the trend of the modern structural system. This paper presents the basic study on the suitable boundary wall in high-rise buildings. The research also demonstrates the evaluation results on sound characteristics in the aspect of sound insulation. The evaluation of sound insulation capability for the commercialized wall structure was conducted based on literature survey while the measurement of sound insulation capability for the light-weght EPP concrete was performed in according to KS F2808 in laboratory. The main objective of this research is to propose the most suitable dry wall system as a sound insulation structure through the comparison and analysis of frequency characteristics and weight-acoustic attenuation.

The Influence of Structural Characteristics of Rear Acoustic Absorbents on Sound Absorption Capability (섬유상 배후내장재의 구조적 특성이 흡음성능에 미치는 영향)

  • Oh, Kyung-Wha;Yoon, Jae-Hee
    • Textile Science and Engineering
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    • v.42 no.6
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    • pp.391-397
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    • 2005
  • In this study, the effects of the thickness, fiber diameter, and solidity of rear acoustic absorbents on sound absorption coefficient were investigated. Polyester $100\%$ nonwovens (needlepunching) consisting of different fiber fineness were selected for rear acoustic absorbents. The capacity of sound absorption was measured by the two-micro-phone impedence measurement tube (KS F 2814), and sound absorption coefficient was calculated. Air permeability (ASTM D 737) was measured to estimate the structural characteristics of acoustic absorbents. It was found that the amount of sound absorption by rear acoustic absorbents increased throughout the whole frequency range with increasing thickness and solidity, and with decreasing fiber diameter, which results from the reduction of air permeability. Based on the results of this study, it is expected that efficient sound absorption capacity through the whole frequency range can be achieved by applying various combination of rear acoustic absorbents to the interior of buildings.

A Study on Acoustical Characteristics in Microcellular Foaming Plastics (초미세 발포 플라스틱의 음향특성 연구)

  • Cha, Sung-Woon;Kim, Hak-Bin;Lee, Byoung-Hee;Kang, Yon-Jun
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.9
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    • pp.71-77
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    • 2008
  • Microcellular foaming plastics create a sensation at polymer industrial for lowering product costs and overcoming a lowering of mechanical intensity. Among many advantages, microcellular foaming plastics is well known to have a good acoustical properties. This research based on the experiment of sound absorption and transmission characteristics inquire into acoustical properties of microcellular foaming plastics. Difference of transmission loss of microcellular foaming plastics and solid materials was defined as cell effect. Also, cell effect is expressed by sound reflection and sound absorption. This study is expected to fundamental research to present economical, functional alternative plan for products using sound absorption and transmission materials.

Sound Characteristics of Traditional Silk Fabrics Generated by Back-and-Forth Friction -Comparison with One-way Friction and Prediction by Mechanical Properties- (왕복마찰에 의한 전통 견직물의 소리 특성 -일방마찰과의 비교와 역학적 성질에 의한 예측-)

  • Yi, Eun-Jou;Kim, Chun-Jeong;Cho, Gil-Soo
    • Textile Science and Engineering
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    • v.44 no.3
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    • pp.172-182
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    • 2007
  • In order to provide prediction models for frictional sound of Korean traditional silk fabrics by mechanical properties, a number of traditional silk fabrics were selected and their sounds by back-and-forth friction were recorded and analyzed in terms of their sound spectral shapes by Fast Fourier Transform(FFT), some quantified physical sound characteristics. Compared to one-way friction sounds, back-and-forth ones of traditional silk fabrics seemed to be both less loud and less rougher and to be more sharper. The values for LPT, ${\Delta}L$, loudness(Z), roughness(Z), and fluctuation strength(Z) were varied among the fabrics while those of sharpness(Z) were similar. The traditional silk fabric groups such as Sa, Dan, Nobangju, and Shantung were significantly differentiated from one another in values of some sound characteristics including LPT, ${\Delta}L$, loudness(Z), roughness(Z), and fluctuation strength(Z). In prediction models by using mechanical properties, surface properties (SMD) and compression properties (RC) were closely related to both physical and psychoacoustic properties.

Luxuriousness Sound Quality Index Development of Electrically Powered Roller Blind (차량용 전동 롤러 블라인드의 고급감 음질지수 개발)

  • Sung, Weonchan;Jo, Hyeonho;Kang, Yeon June;Kim, Seonghyeon;Park, Dongchul
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.5
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    • pp.345-351
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    • 2015
  • Sounds of electrically powered vehicle components such as window lift system, roller blind, etc., are required to be more comfortable and not to irritate the people emotionally. In this paper, a study was conducted to identify the significant sound quality metric and compose the luxuriousness sound quality index of electrically powered vehicle roller blind which is part of vehicle sunroof system. Before conducting subjective evaluation, sound characteristics of roller blind was analyzed and set the target operating sound for subjective evaluation. Thus, transfer sound of roller blind which has the characteristics of sound modulation was used for subjective evaluation. Multiple linear regression analysis was carried out by chosen Zwicker's metrics which are pointed by comments of jurors. Loudness and sharpness related metrics are prime metrics in luxuriousness sound quality index we composed. Also, effect of roller blind assay when it is attached to real vehicle was identified to evaluate the validity of index.

Sound Absorption Properties of Interior Wall Covering Textiles (실내 벽면 마감재의 흡음특성에 관한 연구)

  • Yoon, Jae-Hee;Oh, Kyung-Wha
    • Textile Science and Engineering
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    • v.42 no.4
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    • pp.255-262
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    • 2005
  • In this study, the effects of fabric weave, density, and fiber fineness on the acoustic absorption characteristics of interior wall covering textiles were investigated. Polyester $100\%$ nonwoven (needlepunching) of uniform fiber fineness were selected for rear acoustic absorbents. For the fabric wall covering textiles, acrylic $100\%$ woven fabrics and polyester $100\%$ nonwoven (needlepunching) of different fiber fineness were employed. The capacity of sound absorption was measured by a two-microphone impedence measurement tube (KS F 2814), and sound absorption coefficients were calculated. Air permeability (ASTM D 737) and surface roughness (root mean square's method) were measured to estimate the structural characteristics of interior wall covering textiles. For surface interior wall covering textiles, sound absorption in the high frequency range increased as air permeability increased, but it was irrelevant to the roughness. On the contrary, sound absorption coefficient increased in the low and medium frequency range, as air permeability decreased. Moreover, with an increase in surface roughness, the sound absorption coefficient increased in the low-frequency range. Based on the results of this study, it is expected that efficient sound absorption capacity through the whole frequency range can be achieved by applying various combinations of wall covering textiles to the interior of a building.

Experimental Analysis on Acoustic Characteristics of the Sound-Pipe of King Song-Dok Bell (실험적 분석을 통하여 본 성덕 대왕(聖德 大王) 신종(神鐘) 음통(音筒)의 음향학적 특성)

  • Yoon, Doo-Byung;Kim, Yang-Hann
    • The Journal of the Acoustical Society of Korea
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    • v.16 no.6
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    • pp.19-24
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    • 1997
  • The acoustic characteristics of the sound-pipe of King Song-Dok bell, which is located on the top, are investigated by experiment and simulation. The experimental results;reflection coefficient, and radiation impedance, demonstrate that the sound-pipe is capable of radiating high frequency(above 300Hz) sound; it behave as damper. It is also found that a waveguide model well presens the acoustic characteristics of the sound-pipe.

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Sound Quality Characteristics for Interior Noise of High Speed Train (음질평가를 통한 고속철도 실내소음의 객관적.주관적 특성 분석)

  • Park, Buhm;Kim, Dong-Kyu;Jeon, Jin-Yong;Choi, Sung-Hoon;Park, Jun-Hong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.8
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    • pp.774-781
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    • 2010
  • In Korea, the high-speed train is one of the most important mass transportation. Due to its fast speed, the interior noise level is high and it is one of major reason for passenger complaints. In this study, the response of passengers to interior noise was evaluated using sound quality parameters. The effects of various parameters, such as train types, travel speed, rail road, on the calculated sound quality were investigated. The characteristics of interior noise were identified. The obtained results were compared to auditory experimental data. For precise comparison of noises of similar loudness but with different characteristics, paired comparison method was used. From the comparison, important parameters that have influence on the annoyance and loudness of the noise were determined.

A experimental study for the characteristics of impulse noise caused by shooting of K-7 silenced assault rifle (K-7소음총의 사격음 특성에 대한 실험적 연구)

  • Lee Jin-Ho
    • Journal of the Korea Institute of Military Science and Technology
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    • v.7 no.4
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    • pp.36-43
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    • 2004
  • In 1909 Hiram P. Maxim invented one of the first metal silencers for reducing sound levels in firearms. Silenced me have been mainly applied in the hunting and military operation. In particular special force make use of silenced rifle because it is low sound level. This paper considers experimental analysis for the characteristics of shock wave caused by shooting of a silenced me. Experimental results Indicate that the sound level of K-7 silenced rifle was lower than the sound level of MP5 silenced rifle. And, Sound Power Level of K-7 silenced rifle at a distance more than 75m or loom have nearly the constant value. This results that suggested the characteristics data about K-7 rifle's impulse noise will be apply to design the silencer of a small arms.