• Title/Summary/Keyword: 1/3-Octave Band Level

Search Result 33, Processing Time 0.027 seconds

Field Test and Evaluation of Wind Turbine Noise according to IEC Standards (IEC 규격에 따른 풍력 터빈 소음의 현장 실증)

  • Cheong, Cheol-Ung;Jung, Sung-Su;Cheung, Wan-Sup;Shin, Soo-Hyun;Chun, Se-Jong;Lee, Sang-Hee
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2005.11a
    • /
    • pp.579-582
    • /
    • 2005
  • The sound measurement techniques in IEC 61400-11 are applied to field test and evaluation of noise emission from 1.5 MW wind turbine generator (WTG) at Yongdang-Lee and 650 kW WTG at Hangwon-Lee in Jeju Island. Apparent sound power level, wind speed dependence and third-octave band levels are evaluated for both of WTGs. 1.5 MW WTG at Yongdang is found to emit lower sound power than 660 kW one at Hangwon, which seems to be due to lower rotating speed of the rotor of WTG at Yongdang. Equivalent continuous sound pressure level s (ECSPL) of 650 kW WTG at Hangwon vary more widely with speed than those of 1.5 MW WTG at Yongdang. The reason for this is believed to be the fixed blade-rotating speed of WTG at Yongdang. One-third octave band analysis of the measured data show that the band components around 400-500 Hz are dominant for 1.5 MW WTG at Yongdang and those around 1K Hz are dominant for 660 kW WTG at Hangwon.

  • PDF

Field Test and Evaluation of Noise from Wind Turbine Generators at Yongdang and Hangwon in Jeju Island (제주도 용당/행원 풍력발전기 현장 소음 실증)

  • Cheong, Cheol-Ung;Jeong, Sung-Su;Cheung, Wan-Sup;Shin, Su-Hyun;Jeon, Se-Jong;Lee, Saeng-Hui
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.11a
    • /
    • pp.818-821
    • /
    • 2005
  • The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from 1.5 MW wind turbine generator (WTG) at Yongdang and 660 kW WTG at Hangwon in Jeju Island. Apparent sound power level, wind speed dependence and third-octave band levels are evaluated for both of WTGs. 1.5 MW WTG at Yongdang is found to emit lower sound power than 660 kW one at Hangwon, which seems to be due to lower rotating speed of the rotor of WTG at Yongdang. Equivalent continuous sound pressure levels (ECSPL) of 660 kW WTG at Hangwon vary more widely with wind speed than those of 1.5 MW WTG at Yongdang. The reason for this is believed to be the fixed blade rotating speed of WTG at Yongdang. One-third octave band analysis of the measured data show that the band components around 400-500 Hz are dominant for 1.5 MW WTG at Yongdang and those around 1K Hz are dominant for 660 kW WTG at Hangwon.

  • PDF

Noise Evaluation of the Rumble Strips Constructed at Tall Gate of Highway (고속도로 영업소 광장의 럼블스트립 관련 소음평가)

  • Lee, Jae-Jun;Mun, Sung-Ho;An, Deok-Soon;Kwon, Soo-Ahn
    • International Journal of Highway Engineering
    • /
    • v.14 no.5
    • /
    • pp.201-206
    • /
    • 2012
  • PURPOSES: This study evaluated a measuring technique for tire-pavement interaction noise that uses a noble close proximity (NCPX) method as well as for noise level measured inside of a car (e.g., Inside Noise Level) in term of rumble strips constructed at a tall gate. METHODS: According to the measurements of NCPX and inside noise level (INL), 1/3 octave band frequency analysis and overall noise level calculation were conducted in order to evaluate noise levels of NCPX and INL, depending on types of rumble strips. RESULTS: The tested sections of general concrete pavement surface and two different types of rumble strips were evaluated, using 1/3 octave band frequency analysis and overall noise level. From the analyzed results, it can be concluded that rumble strips generate a relatively huge noise levels when compared to the concrete pavement surface. CONCLUSIONS: Noting that above 3 dBA different noise levels can let drivers know that they are getting close to toll gate; therefore, they should apply their brakes. Thus, the noise levels of rumble strips are required to be reduced, based on considering the neighbors living near toll gates.

A Study for Comparing Road Noise by Surface Types using NCPX (NCPX를 이용한 도로 표층 유형별 노면 소음 비교 연구)

  • Kang, Won Pyoung;Moon, Hak Ryong
    • International Journal of Highway Engineering
    • /
    • v.15 no.6
    • /
    • pp.61-68
    • /
    • 2013
  • PURPOSES : The purpose of this study is to study the noise reducing effect of Micro Surfacing by comparing general asphalt, longitudinal tining and Slurry Seal. METHODS : This study measures vehicles' noise of each section by the NCPX method that can measure noise between the road surface and the tire at the field. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the field data of each section. Total sound pressure level is compared by ANOVA test statistically. After ANOVA test, post-hoc test is conducted to know mean difference of surface type by Tukey. RESULTS : As the result of CPB analysis to confirm sound pressure levels by frequency, it was shown that sound pressure levels by frequency are totally similar except for those of frequency bands between 100Hz and 500Hz. The result of ANOVA test and post-hoc test, it was shown that sections of surface type have a difference. The result of Micro Surfacing was lower 2~5dB(A) than other surface type. CONCLUSIONS : It is found that the noise reduction performance of Micro Surfacing was better than other surface type.

The Study of Improvement of the Void Slab Applying the Impedance Method (임피던스법을 이용한 보이드 슬라브의 개선방안에 관한 연구)

  • 오재응;김영식
    • Journal of KSNVE
    • /
    • v.11 no.2
    • /
    • pp.276-284
    • /
    • 2001
  • In apartment buildings, floor-impact sound has been regarded as the major source that causes complaints from residents. It is mainly due to the use of light-weight structures and the lack of researches in terms of floor-impact sound. The purposes of this study are analyzing the characteristics of vibration response and sound radiation of 12type void slabs in the improvements void slab by impedance method and finding the fittest improvements void slab on the 12type void slab. The main results of this study are summarized as below: (1) In the $\frac{1}{3}$ octave band level of sound radiation, $\frac{1}{3}$ octave band levels, measured from four-divided improvement void slab(No.8) and eight-divided improvement void slab(No.12), are 10~25 dB lower than that of standard void slab(No.1) in the 1250 Hz. Especially, eight-divided improvement void slab(No.12) is the best void slab in terms of radiation efficiency of sound level. (2) In the correlation relation of acceleration and sound radiation, standard void slab(No.1), four-divided improvement void slab(No.8), SK standard four-hole void slab(No.10), and eight-divided improvement void slab(No.12) are positive correlation relation.

  • PDF

Characteristic of Road Traffic Noise According to Road Vertical Alignment (도로 종단선형에 따른 도로교통 소음 특성 분석)

  • Moon, Hak Ryong;Han, Dae Cheol;Kang, Won Pyoung
    • International Journal of Highway Engineering
    • /
    • v.15 no.4
    • /
    • pp.95-105
    • /
    • 2013
  • PURPOSES: The purpose of this study is to research the influence of road traffic noise by road slope through the analysis of the field road traffic noise and determine consideration of road slope in the case of appling active noise cancellation. METHODS: This study measures vehicle's noise by the NCPX method at the three field sections such as uphill, downhill, and flatland. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the raw field data. Total sound pressure level is compared by ANOVA test and T test statistically. The results obtained are compared in accordance with the road slope and the progress of the uphill section. RESULTS : The noise characteristic of early, medium, and last parts of uphill was found to be consistent when the vehicle was travelling uphill section. The result of statistical test, it was shown that total sound pressures are not different each other. According to the comparison by the geometry, sound pressure of the uphill section was higher than those of the flatland and downhill section in high frequency band. By the result of statistical test, total sound pressure are different according to geometry in the case of high vehicle speed. In the comparison result by road slope, each sound pressure level was found to be consistent in total frequency. However, total sound pressure proportionally increased according to road slope. CONCLUSIONS: It is found that the effect of road slope on noise generation was little in this experimental sites.

A Study on the Development of a New Muffler Component required in the Geometrically Constrained Space (제한된 공간에 맞는 새로운 소음기부품의 개발에 대한 연구)

  • 이정권;이병호
    • The Journal of the Acoustical Society of Korea
    • /
    • v.1 no.1
    • /
    • pp.76-81
    • /
    • 1982
  • To get minimum noise level by making full use of the constrained geometric space and being compatible with the minimum pressure-drop condition, 3-pipe through-flow system is designed by inserting a new pipe which is shaped a resonator in the cavity of 2-pipe system. As a result of the 1/3-octave-band frequency analysis for the noise reduction characteristics, this system is proved to have good sound attenuation effect in the high frequency region, so that it is found to be a useful component of a muffler.

  • PDF

Au Experimental Study on the Aerodynamic Noise by a Circular Jet Impinging on a Plate (평판에 충돌하는 원형분류의 공력소음에 관한 실험적 연구)

  • 이동훈;권영필;한희갑
    • Journal of KSNVE
    • /
    • v.7 no.1
    • /
    • pp.71-79
    • /
    • 1997
  • The objective of this study is to investigate experimentally the effect of surface conditions of the plate on the impinging jet noise. The experimental results about the spectrum, the sound pressure level and the directivity are pressented and discussed in relation with the surface conditions. Regardless of the surface conditions, the pure tones of high level are generated at the same frequency band and the overall sound power level of impinging jets is much higher than that of the free jet. However, the velocity dependence of the sound pressure level and the directivity are different between smooth surfaces and rough surfaces. The dependence of sound pressure level on the jet velocity shows that the smooth surface generates quadrupole-type sound like free jets. However, the perforated or the rough surface radiates sound power exactly proportional to the sixth power of the jet velocity, indicating that the source is fixed dipole type. The directivities of 1/3 octave band sound pressure level for both the free and impinging jet show the peak directivity at 115$^\circ$ upstream, probably due to the refraction associated with velocity gradient.

  • PDF

A Study on the Characteristics of Sound Insulation at the Circular Voided Concrete Floor in the Multi-Housing (공동주택에서 중공 슬래브 바닥의 차음 특성에 관한 연구)

  • 손철수
    • Journal of the Korean housing association
    • /
    • v.11 no.1
    • /
    • pp.171-181
    • /
    • 2000
  • The purpose of the resent research is to investigate the characteristics of sound insulation at the circular voided concrete slab in the multi-housing. In order to do this research, the method for field measurement of floor impact sound level was used following the Korea Standard F2810-1996. For the multi-housing, three kinds of circular voided concrete slabs are used to measure the characteristics of sound insulation.The results are as follows; 1.The main factor affecting the characteristics of sound insulation at the circular voided concrete slab in the multi-housing is sound-absorbing materials in the circular tube. 2. The main factor to effect the difference of sound pressure level is circular tube in the concrete slab. 3. The forms of circular tubes effect the characteristics of sound insulation at the circular tube. 4. Sound Pressure Level resulting from the piping direction of circular tubes in little different to octave band level.More study will be needed about the depth and distance of sound insulation materials, and the components of sound insulation materials for the multi-housing.

  • PDF

Analysis of Vehicle Noise Effect by Microphone Position and Road Geometry (도로 기하구조에 따른 차량 Microphone 위치별 소음 영향 분석)

  • Moon, Hak Ryong;Han, Dae Cheol;Kang, Won Pyoung
    • International Journal of Highway Engineering
    • /
    • v.15 no.4
    • /
    • pp.75-83
    • /
    • 2013
  • PURPOSES: The purpose of study is to understand the characteristic of driving noise from the front and rear tire for effective active noise cancellation application. METHODS : As literature review, noise measurement methods were reviewed. Noise measurement conducted at three kind of section by road slope using CPX(Close Proximity Method). Noise data was compared by total sound pressure level and 1/3 octave band frequency sound pressure level. Also, each section was compared by T-test using SPSS. RESULTS : In the case of the uphill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low and high frequency band. In the case of high slope section of Sangsaek-Ri, the sound pressure level of the front tire was higher than that of the rear tire in high frequency. Also, in the case of the downhill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low frequency band. However, the sound pressure levels of both the front and rear tires were approximately the same in the high slope section of Sangsaek-Ri. The result of T-test showed that total sound pressures of the front and rear tires were not different from each other in the case of high slope and high speed. CONCLUSIONS: Road slope was not an important variable for effective active noise cancellation.