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Perception of amplitude-modulated noise from wind turbines (풍력발전기 소음의 진폭변조에 대한 예측 및 인지 가능성 고찰)

  • Lee, Seunghoon;Kim, Hogeon;Kim, Kyutae;Lee, Soogab
    • 한국신재생에너지학회:학술대회논문집
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    • pp.180.1-180.1
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    • 2010
  • Wind turbine noise is generally lower than that from other environmental noise sources such as road and railway noise. Nevertheless, some residents living more than 1km away from wind turbines have claimed that they suffer sleep disturbance due to wind turbine noise. Several researchers have maintained that residents near a wind farm may perceive large amplitude modulation of wind turbine noise at night, and this amplitude modulation is the main cause of the noise annoyance. However, to date only few studies exist on the prediction of the amplitude modulation of wind turbine noise. Thus, this study predicts amplitude modulated noise generated from a generic 2.5MW wind turbine. Semi-empirical noise models are employed to predict the modulation depth and the overall sound pressure level of the wind turbine noise. The result shows that the amplitude modulation is observed regardless of atmospheric stability, but the modulation depth in a stable atmosphere is 1~3dB higher than that in an unstable atmosphere near the plane of rotation where the blades move downward. Moreover, using the result of the noise prediction, this study estimates the maximum perceptible distance of the wind turbine noise cause by amplitude modulation. The result indicates that the wind turbine noise can be perceived at a distance of up to 1600m in the range of about 30~60 degree from the on axis in a extremely low background noise environment.

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Assessment Method of Noise Exposed Population for Manufacture Type of Noise Map (소음지도제작방법에 따른 소음노출인구산정방법)

  • Park, In-Sun;Oh, Jong-Hwa;Park, Sang-Kyu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1129-1133
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    • 2007
  • Assessment of noise exposed population is a method for checking the degree of environmental noise and social influence in order to reduce the risks such as annoyance and disturbance that are generated by environmental noise. Also, this method suggests the preferential noise reduction policy and action plan by accurately assessing the area that noise causes harm to human health. Recently, a noise map, which can predict noise in comprehensive areas, is used for the assessment of noise exposed population, breaking from the methods using existing measures. In particular, countermeasure for the noise can be considered more effectively by using assessment methods of noise exposed population for specific noise levels, areas, and building types which are the main input factors in noise maps. In this study, Assessment methods of noise exposed population by using 2D noise map are compared with those by 3D noise map.

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Comparative Study on Annoyance of Traffic and Aircraft noise (도로소음과 항공기소음의 성가심 반응 비교 연구)

  • Lee, Ki-Jung;Chang, Seo-Il;Lee, Kun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.131-134
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    • 2005
  • This study examine the annoyance of transportation noise exposure and found the survey method about which noise induces more disturbance or annoyance when more than two kinds of noise exist. This study describes the noise annoyance survey performed in the vicinity of Sin-wol interchange. This residential area was exposed to aircraft noise and traffic noise simultaneously and aircraft noise exposure of this area is about 81 WECPNL, traffic noise exposure is about 81.2 dB(A) nearby road. Noise sources are grouped into three part, traffic noise, aircraft noise and community noise. The questionnaire includes how often, how loud each noise is heard. Also this deals with comparative annoyance reaction from specific noise sources such as aircraft or traffic and its disturbance of daily activities. Facade noise mapping are executed by using a commercial noise mapping software.

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A Comparative Study on the Noise Exposed Population for Noise Map Types (소음지도 형태에 따른 소음노출인구 비교 연구)

  • Park, In Sun;Park, Jae Sik;Park, Sang Kyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.2
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    • pp.99-104
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    • 2013
  • Assessment of noise exposed population is to check the environmental noise level and social influence in order to reduce the risks such as annoyance and disturbance that are generated by environmental noise. Also, this method suggests the preferential noise abatement policy and action plan by accurately finding the area that the noise causes harmful effect to human health. Recently, a noise map, which can predict noise in comprehensive areas, is used for the assessment of noise exposed population, breaking from the methods using existing measures. In particular, countermeasure for the noise can be considered more effectively by using assessment methods of noise exposed population for specific noise levels, areas, and building types which are the main input factors in noise maps. In this study, assessment methods of noise exposed population by using 2 dimensional noise map are compared with those by 3 dimensional noise map.

A Study on the Establishments of Aircraft Noise Abatement Procedures in Gimpo International Airport (김포공항 항공기 저소음 운항절차 수립을 위한 연구)

  • Kim, Yeon-Myung;Park, Jin-Woo;Kim, Young-Il;Son, Jung-Gon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.725-738
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    • 2006
  • The final purpose of this study is to develop noise abatement procedures for minimizing damages caused by aircraft noise, to establish appropriate noise limits and to suggest a plan for imposing surcharges and penalties on aircraft infringing the noise limits. This study establishes noise abatement procedures and suggests a plan to complement and improve upon NMS in Gimpo International Airport by reviewing the NMS structure. In addition, this study establishes a noise limit at each noise monitoring system and a verification system to discriminate infringing aircraft. Finally, this study suggests a control plan for aircraft infringing the noise limit.

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Numerical study on the machine room axial flow fan of a refrigerator (냉장고 기계실 축류홴 소음의 수치적 연구)

  • Jeon, Wan-Ho;Kim, Wook;Shin, Dae-Sig;Kim, Hyun-Joo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1002-1006
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    • 2006
  • The noise of a refrigerator is consisted of the various flow noises of a refrigerator fan, a compressor and a condenser fan. The demands of high flow rate, compact space and low noise are to be accommodated, especially, in the case of a premium refrigerator. In this study, flow field, noise sources and flow noise are analyzed numerically and compared to the measured data. The flow field is calculated with 3-dimensional CFD solver - SC/Tetra, and the noise source and aeroacoustic noise is analyzed with FlowNoise S/W. Low noise axial fan can be developed by controlling the dominant noise source area.

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A Mixed Nonlinear Filter for Image Restoration under AWGN and Impulse Noise Environment

  • Gao, Yinyu;Kim, Nam-Ho
    • Journal of information and communication convergence engineering
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    • v.9 no.5
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    • pp.591-596
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    • 2011
  • Image denoising is a key issue in all image processing researches. Generally, the quality of an image could be corrupted by a lot of noise due to the undesired conditions of image acquisition phase or during the transmission. Many approaches to image restoration are aimed at removing either Gaussian or impulse noise. Nevertheless, it is possible to find them operating on the same image, which is called mixed noise and it produces a hard damage. In this paper, we proposed noise type classification method and a mixed nonlinear filter for mixed noise suppression. The proposed filtering scheme applies a modified adaptive switching median filter to impulse noise suppression and an efficient nonlinear filer was carried out to remove Gaussian noise. The simulation results based on Matlab show that the proposed method can remove mixed Gaussian and impulse noise efficiently and it can preserve the integrity of edge and keep the detailed information.

A Study on the Establishments of Aircraft Noise Abatement Procedures in Gimpo International Airport (김포공항 항공기 저소음 운항절차 수립을 위한 연구)

  • Kim, Yeon-Myung;Park, Jin-Woo;Kim, Young-Il;Son, Jung-Gon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5
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    • pp.379-390
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    • 2007
  • The final purpose of this study is to develop noise abatement procedures for minimizing damages caused by aircraft noise, to establish appropriate noise limits and to suggest a plan for imposing surcharges and penalties on aircraft infringing the noise limits. This study establishes noise abatement procedures and suggests a plan to complement and improve upon NMS in Gimpo International Airport by reviewing the NMS structure. In addition, this study establishes a noise limit at each noise monitoring system and a verification system to discriminate infringing aircraft. Finally, this study suggests a control plan for aircraft Infringing the noise limit.

Analysis on Indoor Noise Condition of Cafeteria in University Campus (대학교 학생식당의 소음저감을 위한 실내소음 실태분석)

  • Choi, Yoon-Jung;Lee, Seon-A;Kim, Hye-Kyeong
    • Proceedings of the Korean Institute of Interior Design Conference
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    • pp.85-88
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    • 2007
  • This research is a case study for improving the sound environmental quality of cafeteria in university campus. The purpose of the study is to investigate the present condition of physical level, type, and source of indoor noise by comparison with a restaurant near campus. Methods were field survey with measurement on equivalent and instant noise level and observation on noise type, and questionnaire survey to 60 students users. Surveys were carried out in the 8th and the 14th of December 2005. The results are as follows. 1) Indoor noise levels of the cafeteria were measured as $67.2{\sim}76.6$(average 73.3) dB(A)Leq5min and $60.3{\sim}90.5$(average 71.2) dB(A), but noise levels of the restaurant were $61.6{\sim}70.4$(average 66.9) dB(A)Leq5min and $59.8{\sim}70.6$(average 64.9) dB(A). 2) The users's responses on major noise type were 'noise by handling equipment and tableware', 'noise by moving chairs', and 'taking noise' in cafeteria, but 'taking noise' and 'background music' in restaurant. 3) It was found that the differences of indoor noise condition between with 2 subjects were caused by finishing materials, kitchen division type, and furniture type.

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A Study on the Structure-borne Noise and Noise Reduction of Drainage Pipes (배수관의 구조소음과 소음저감에 관한 연구)

  • Ryu, B.J.;Lee, G.S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.194-202
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    • 2009
  • The paper deals with the countermeasure against structure-borne noise source and noise reduction of drainage pipes. Recently, the problem the problem of the toilet drain noise of an apartment house has been become the center of public interest and a target of public grievance. Generally, the drain noise of a toilet in the apartment house has a pink noise characteristics below 2 kHz level, and therefore, the structure-borne noise has a great effect on the entire drain noise. In order to measure the transmission loss for various kinds of pipes such as PVC pipes, cast-iron pipes and newly developed AS pipes, experimental setup containing speakers as a sound source was designed and manufactured. The second-stories measurement room with a small size anechoic chamber was constructed and the noise level for different kinds of drainage pipes was measured by the sound level meter. Through the experimental research in the study, noise reduction capacity for various kinds of drainage pipes and countermeasures against structure-borne noise source are demonstrated.

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