• Title/Summary/Keyword: Noise Performance

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Classification of Noise Insulation Performance in Apartment Buildings through Noise survey and Auditory Experiment (설문조사와 청감실험을 통한 공동주택 차음성능의 평가등급 설정)

  • Ryu, Jong-Kwan;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.666-669
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    • 2005
  • Social noise survey and auditory experiment on residential noises such as floor impact, air-borne, bathroom, drainage and traffic noises were conducted to classily a noise insulation Performance in apartment building. The survey results showed that annoyance among subjective responses to residential noises was most greatly affecting to satisfaction with noises. In the survey, boundary limit between satisfaction and dissatisfaction was also determined. Auditory experiments was also undertaken to determine noise insulation performance according to the percent of satisfaction for individual noise source. Result of auditory experiment showed that the noise insulation performance for floor impact, airborne, drainage and traffic noise corresponding to 40 % satisfaction is 49 dB (L$_{i,Fmax,AW}$), 48 dB (R'w), N-41, and N-40, respectively. Finally, classes of noise insulation performance in apartment building were proposed according to satisfaction with noises

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Improvement Noise Attenuation Performance of the Active Noise Control System Using RCMAC (RCMAC를 이용한 능동소음 제어시스템의 소음저감 성능개선)

  • Han, S.I.;Yeo, D.Y.;Kim, S.H.;Lee, K.S.
    • Journal of Power System Engineering
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    • v.14 no.5
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    • pp.56-62
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    • 2010
  • In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.

Comparison of ERG Denoising Performance according to Mother Function of Wavelet Transforms (웨이브렛 변환의 모함수에 따른 ERG의 잡음제거 성능 비교)

  • Seo, Jung-Ick;Park, Eun-Kyoo;Jang, Jun-Young
    • Journal of Korean Clinical Health Science
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    • v.4 no.4
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    • pp.756-761
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    • 2016
  • Purpose. Noise occurs at measuring Electoretinogram(ERG) signals as the other bio-signal measurement. It is compared the denoising performance according to the mother function of wavelet transforms. Methods. The ERG signal that generated power supply noise and white noise was used as a sampling signal. The noise of ERG signal was filtered by using haar, db7, bior mother function. The filtering performance of each mother functions was compared using Fourier transform spectrum and SNR(signal to noise ratio). Results. In the haar functioin, the result of the Fourier transform spectrum was that the power supply noise is removed and the white noise performance is not good. The SNR was 27.0404. In the db7 function, the results of Fourier transform spectrum was that the power supply noise is removed and the white noise performance is good. The SNR was 35.1729. In the db7 function, the results of Fourier transform spectrum was that the power supply noise is removed and the white noise performance is the bset. The SNR was 35.4445. Conclusions. The db7, bior function was good results in power supply noise and white noise filtered. The bior function is suitable for filtering noise of the ERG signal.

Acoustic Properties of Temporary Noise Barriers on Construction Site (건설공사장 가설방음벽의 음향 특성)

  • Chung, Jin-Yun;Im, Jung-Bin;Lee, Sung-Chan
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.2
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    • pp.191-198
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    • 2010
  • The noise by the construction activities is one of the main issues in Korea. To prevent the noise from construction site, construction company installs temporary noise barriers along the construction site boundary. Normally sound insulation performance ($R_w$) of the temporary noise barriers made by metal or plastic is between 18 and 31 dB and metallic noise barriers are around 5 dB higher than plastic noise barriers. Sound absorption performance (NRC) of the temporary noise barriers are between 0.20 and 0.59 so it's difficult to characterize their acoustic performance. In this study, it has founded that sound insulation performance of the temporary noise barrier has been improved about 3dB by stick the high density acoustic sheet and insertion loss of noise barrier is getting increased as the source and receiver approached the temporary noise barriers.

Variation of the Sound Insulation Performance of Window in the Apartment House depending on the Sound Source Characteristics (공동주택에서 음원특성에 따른 외부창호 차음성능 변화)

  • Park, Hyeon-Ku;Lee, Ok-Kyun;Han, Dong-Hwa;Song, Hyuk;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1735-1740
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    • 2000
  • The aim of this study is to analyze the sound insulation performance of windows depending on the sound source types and to propose the noise control method in the apartment house. The regions where apartment houses are constructed are varied in the dominant noise sources such as aircraft noise, railway noise and road traffic noise. For the experiment, nine noise sources including pink noise were selected and recorded, which was used in the experiment by reproducing. As a result of this study, the sound insulation performance of window was found that when the frequency contents of the noise were high level in all frequency bands the difference of sound insulation performance was negligible, but when the frequency contents were low level at particular frequency band the difference of sound insulation performance was shown very differently.

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Performance Improvement of the Active Noise Control System Using RCMAC and PSO Method (RCMAC 및 PSO 기법을 이용한 능동 소음제어 시스템 성능 개선)

  • Han, Seong-Ik;Shin, Jong-Min;Kim, Sae-Han;Lee, Kwon-Soon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.10
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    • pp.1900-1907
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    • 2010
  • In this paper, a recurrent cerebellar modulation articulation control with praticle swarm optimization (PSO) method has been investigated for improvement of noise attenuation performance in active noise control system. For narrow band noise, FXLMS and RCMAC has a partial satisfactory noise attenuation. However, noise attenuation performance is poor for broad band noise and nonlinear path since it has linear filter structure. To improve this problem, a RCMAC with PSO is proposed and it is shown that satisfactory noise attenuation performance is obtained by some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source.

A Study on the Performance Evaluation of Noise Reduction for Railway Noise Barrier using Prediction Equation (예측식을 이용한 철도방음벽의 성능평가에 관한 연구)

  • Cho, Jun-Ho;Koh, Hyo-In
    • Journal of Environmental Impact Assessment
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    • v.19 no.6
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    • pp.553-561
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    • 2010
  • Railway noise barrier is generally used with welding of joint rail for railway noise reduction in our country. In this study, method for performance evaluation of railway noise barrier using insertion loss was suggested in case of without having noise measurement results before barrier installation. For this, railway noise measurements were performed in commercial high-speed railway site which has railway noise barrier. As a noise level before noise barrier installation, predicted noise level were used. From this method the performance evaluation for railway noise barrier were performed accurately and efficiently.

Effect of noise barrier on aerodynamic performance of high-speed train in crosswind

  • Zhao, Hai;Zhai, Wanming;Chen, Zaigang
    • Wind and Structures
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    • v.20 no.4
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    • pp.509-525
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    • 2015
  • A three-dimensional aerodynamic model and a vehicle dynamics model are established to investigate the effect of noise barrier on the dynamic performance of a high-speed train running on an embankment in crosswind in this paper. Based on the developed model, flow structures around the train with and without noise barrier are compared. Effect of the noise barrier height on the train dynamic performance is studied. Then, comparisons between the dynamic performance indexes of the train running on the windward track and on the leeward track are made. The calculated results show that the noise barrier has significant effects on the structure of the flow field around the train in crosswind and thus on the dynamic performance of the high-speed train. The dynamic performance of the train on the windward track is better than that on the leeward track. In addition, various heights of the noise barrier will have different effects on the train dynamic performance. The dynamic performance indexes keep decreasing with the increase of the noise barrier height before the height reaches a certain value, while these indexes have an inverse trend when the height is above this value. These results suggest that optimization on the noise barrier height is possible and demonstrate that the designed noise barrier height of the existing China Railway High-speed line analysed in this article is reasonable from the view point of the flow field structure and train dynamic performance although the noise barrier is always designed based on the noise-related standard.

Design Parameter Analysis on the Performance and Noise of Axial Fan (축류형 홴 성능 및 소음에 영향을 미치는 설계변수 분석)

  • 김기황;이승배;주재만
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11a
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    • pp.275-281
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    • 2001
  • While basic input parameters for the performance and noise of axial fan are flow rate, pressure rise, rotating speed, and fan diameter, the geometric parameters of blade are sweep angle, solidity, and camber angle. The sweep angle does not affect fan performance much, but on fan noise significantly. Solidity and camber angle are very critical design parameters acting on the fan performance directly. The solidity and camber angle are closely related, therefore they have to be carefully determined for the low-noise and high-performance fan. In This paper, different design points are selceted and also geometric parameters are deliberately changed for the comparison of fan noise. As a result, at the same performance, the input rotational speed affects radiated noise more significantly than others. When solidity and camber angle are increased more than those by iDesignFan/sup TM/ program, more noise is experienced. The blade sweep method and blade numbers at same solidity are observed to results in different levels of performance and noise.

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The relationship between noise awareness, hearing ability, and dental hygiene performance in dental hygienists (치과위생사의 치과 내 소음인식도와 청력관련 특성 및 업무와의 관련성)

  • Park, Kyung-Hwa;Kim, Hyo-Jin
    • Journal of Korean society of Dental Hygiene
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    • v.15 no.1
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    • pp.11-17
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    • 2015
  • Objectives: The purpose of the study is to investigate the relationship between noise awareness, hearing ability, and dental hygiene performance in dental hygienists. Methods: The subjects were 234 dental hygienists in Seoul, Gyeonggi-do, and Incheon. The questionnaire consisted of 3 questions of general characteristics of the subjects, 1 question of noise awareness, 3 questions of hearing ability, 5 questions of dental hygiene performance, 1 question of noise reduction necessity, and 2 questions of noise control. Noise awareness, dental hygiene performance, and noise reduction necessity were measured by Likert 5 scale. Cronbach's alpha was 0.825 in dental hygiene performance reliability. Results: There was a significant difference in noise recognition by age(p<0.01) and working career(p<0.05). Those who pumped up the higher TV volume accounted for 31.6% and 3.0% had hearing impairment in the regular health checkup. 3.4% of the respondents complained of hearing loss, ear fluid, and equilibrium problem diagnosed by the doctors. The relationship between the type of workplace environment and task performance showed a significant difference. Those who work in the dental hospitals had high score of 3.43, while those who work in dental clinics had 3.20(p<0.05). The increased level of noise recognition affected the task performance and it is necessary to reduce the noise level. More try must be focused on the noise exposure prevention. Conclusions: In order to reduce the problems due to noise and improve their quality of life, it is necessary to change the noise recognition in the work place.