• Title/Summary/Keyword: Measurement noise

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A Study on the Plan for Advanced Noise-Policy in the 21st Century (21세기 소음정책 선진화 방안 고찰)

  • Yang, Geun-Ho;Park, Young-Min;Lee, Nae-Hyun;Chang, Yoon-Young
    • Journal of Environmental Impact Assessment
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    • v.18 no.1
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    • pp.21-30
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    • 2009
  • The study show that things about the noise control are indicated at The Noise & Vibration Control Act and the other Act. Also, the details program and total government ministries' program for the noise control are indicated what are the advance noise control plan. The study consist of the four part which are "Draw up the environmental noise infrastructure plan; the install shall be done the noisemap & the automatic noise measurement devices", "Resetting of environmental noise standard at the application area and Introduce of indoor noise; the guide for region classification of the noise standard & indoor noise", "Setting of aircraft noise standard and Program of measurement point operation; the noise-assessment-standard shall change from WECPN to new index($L_{den}$, $L_{dn}$, $L_{Aeq\;24h}$) & the operation and control of aircraft noise measurement changes from local environmental office to central control center" and "The method of noise regulation at construction site and the plan on making of standard for vibration regulation; It shall be made that the guideline of construction noise should include a target-construction, noise standard etc & the ministries shall unify control about construction vibration of the blasting vibration". The advance noise-policy will improve efficiency to deal with civil appeal & damage on residents about noise.

Elimination of Self Noise & Doppler Effects from the Microphone Array Measurement (마이크로폰 어레이 측정에서의 도플러 효과와 자체소음 제거에 관한 실험적 연구)

  • Rhee, Wook;Park, Sung;Kim, Jai-Moo;Choi, Jong-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.7 s.112
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    • pp.677-682
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    • 2006
  • In the case of aeroacoustic test in windtunnel, measurement accuracy is reduced by not only Doppler effects but also by the microphone self noise due to airflow and high turbulence in the wall boundary layer. Microphone array measurements can be easily utilized for the solutions of these problems. In this paper, geometrical optics approach and diagonal term elimination of cross spectral matrix was introduced to the de-dopplerization and self noise reduction methods for the microphone array measurement. For the validation, beamforming tests for sinusoidal point source were performed in the closed type test section of windtunnel, and their performances of beam width and sidelobe rejection were significantly improved.

An Study KS Standardization for Acoustic noise measurement of the Wind Turbine (풍력발전시스템 소음평가의 KS 규격화에 관한 연구)

  • Son, C.Y.;Kim, J.H.;Oh, D.H.;Park, J.B.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.406-410
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    • 2005
  • The wind turbine, Europe and the United States are different with the standards process each other when the manufacturing company which in order to demand the standards process to a construction in the multi country with interested parties of the corresponding nation to, always the re-agreement is difficult. Korean wind turbine also detail there is not a standard, when it produces and establishes of wind turbine, the problem point occurs. It is like that investigation of international standards system it leads and when it prepares the Acoustic noise measurement of the Wind Turbine Systems of Korea, it prepares the base for industrial development wind turbine of Korea.

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Elimination of Self Noise & Doppler Effects from the Microphone Array Measurement (마이크로폰 어레이 측정에서의 도플러 효과와 자체소음 제거에 관한 실험적 연구)

  • Rhee, Wook;Park, Sung;Choi, Jong-Soo;Kim, Jai-Moo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.822-825
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    • 2005
  • In the case of aeroacoustic test in windtunnel, measurement accuracy is reduced by not only Doppler effects but also by the microphone self noise due to airflow and high turbulence in the wall boundary layer. Microphone array measurements can be easily utilized for the solutions of these problems. In this paper, geometrical optics approach and diagonal term elimination of cross spectral matrix was introduced to the de-dopplerization and self noise reduction methods for the microphone array measurement. For the validation, beamforming tests for sinusoidal point source were performed in the closed type test section of windtunnel, and their performances of beam width and sidelobe rejection were significantly improved.

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A Study on Interior Noise Contribution Analysis of Trains based on OTPA Method (OTPA방법을 이용한 철도차량 실내 소음 기여도 분석 연구)

  • Jung, Jae-Deok;Hong, Suk-Yoon;Song, Jee-Hun;Kwon, Hyun-Woung;Noh, Hee-Min;Kim, Jun-Kon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.1
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    • pp.97-103
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    • 2016
  • The sensitivity of interior noise that the passengers perceive is comparatively high in the train, and structure-borne and air-borne types of noises come into the train. In this paper, to analyze contributions of these noise sources operational transfer path analysis(OTPA) is used. OTPA has some advantages of executing the contribution rates of several sources simultaneously, and in this work, 29 points are measured while running. Transfer functions between reference measurement points and response measurement points are calculated by the singular value decomposition(SVD) and Principal component analysis(PCA) method, and the frequency characteristics of the noise source are successfully derived. Also the interior noise is predicted and compared with measurement data to show the reliability.

Sunroof Wind Noise Reduction Using Automatic Noise Measurement and Analysis System (자동 소음 계측 및 분석 장치를 이용한 자동차 썬루프 윈드노이즈 저감 기술 개발)

  • Shin, Seong-Ryong;Kim, Heung-Ki;Jung, Seung-Gyoon;Kook, Hyung-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11b
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    • pp.166-169
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    • 2005
  • The best sunroof wind noise quality is mainly related to the sunroof deflector which affects both low-speed buffeting and high-speed aerodynamic noise. An automatic deflector-moving and noise-measuring apparatus is developed to obtain hundreds of measuring data which haven't been available by hand. With an additional program for fast and easy noise analysis, this device leads quickly to the better position and angle of the deflector. Now, the 'better' means the lower noise level and the robuster design solution. From these kinds of better solutions, more meaningful guidelines on the deflector design and sunroof wind noise reduction can be suggested.

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Modeling of GPS measurement noise for estimating smoothed pseudorange and ionospheric delay (평활화 된 의사거리 및 전리층 지연 추정을 위한 GPS 측정치 잡음 모델링)

  • Han, Deok-Hwa;Yoon, Ho;Kee, Chang-Don
    • Journal of Advanced Navigation Technology
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    • v.16 no.4
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    • pp.602-610
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    • 2012
  • Ionospheric delay error, one of main error sources in GPS signal, varies with signal frequency. Dual-frequency user uses L1, L2 frequency pseudorange to estimate the ionospheric delay, and there are errors caused by pseudorange measurement noise. So, filter is usually used to smooth the measurement. Weighted hatch filter can estimate optimal smoothed pseudorange measurement. But measurement noise model is needed to use this filter. In this paper, measurement noise modeling is conducted for NDGPS reference station. Using noise modeling result, weighted hatch filter estimate smoothed pseudorange measurement and ionospheric delay. Standard deviation of ionospheric dealy error drops to one-twenty fifth of non-filtered result.

A study on the performance test and acoustic design of interference type noise reduction device for railway noise (철도소음 저감을 위한 간섭형 방음장치 음향 설계 및 성능시험에 관한 연구)

  • Cho, Jun-Ho;Koh, Hyo-In
    • Journal of Environmental Impact Assessment
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    • v.20 no.6
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    • pp.787-795
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    • 2011
  • Noise barrier is generally used with welding of joint rail for railway noise reduction in our country. But the noise barrier for high speed railway has weak point in low frequencies about 315Hz band. In this study, For developing of Interference-type Noise Reduction Device(INRD), acoustic analysis were performed using commercial software. For verifying the improvement in the noise reduction, noise measurement before and after installing of INRD were performed in Anechoic Chamber. From these acoustic analysis and noise measurement, it was known that developed INRD has a good noise reduction performance and can be used efficiently with conventional noise barrier.

The Analysis of Vehicle Interior Noise by the Powertrain, and Measurement of Noise Trasnsfer Function using Vibro-Acoustic Reciprocity (파워트레인에 의한 차량 실내 소음 특성 및 전달 함수 측정)

  • Kim, Sung-Jong;Lee, Sang-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.501-506
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    • 2007
  • Structure-borne noise is the interior noise that results from the low frequency vibrational energy transmitted through those body and joint parts. The relation between the excitation of powertrain and resultant interior sound must be analyzed in order to identify and predict the structure borne noise. The method of acoustic source excitation is preferred than the method of mechanical force excitation to measure the NTF(noise transfer function). Because acoustical method is more convenient and reliable. In this paper, to analysis and identify vehicle interior noise by powertrain is performed, and the vibro-acoustic transfer function is extracted from experimental measurement. These are important step of TPA(transfer path analysis) to identify effect of interior noise resulted from powertrain running excitation.

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A Noise Characteristics and Countermeasures of FPSO Topside (FPSO Topside의 소음특성 파악 및 저감대책)

  • Kim, Dong-Hae;Kim, Sung-Hoon;Chung, Kun-Hwa
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11b
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    • pp.73-76
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    • 2005
  • Recently, the demand for the Floating, Production, Storage, and Offloading facility (FPSO) which has some economic and technical advantages, has increased in offshore oil production areas. FPSO vessel dose not have self-propulsion system, but has additional facilities for oil production and positioning system. Main noise sources such as gas turbines, compressors, and pumps, are located on top of the hull (Topside area). In general, the noise regulation for the offshore structure is severer than that of the cargo ship and acceptable noise limit of cabin is specified as 45 dB(A). This paper describes the noise characteristics and the countermeasures for FPSO Topside area through investigation of noise analysis and site measurement results. Proper countermeasures, considering the characteristics of sources and receiver spaces, were applied from the noise prediction and various measurement results. Finally, this ship was successfully delivered with excellent noise properties.

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