• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.2
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• pp.128-136
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• 1995

The purpose of this study is to evaluate the difference of noise level according to noise measuring methods in the noisy working environments. Sound pressure level(SPL), equivalence sound level(Leq) and personal noise exposure dose(Dose) in the fifty-nine unit workplaces of the twenty-eight industries were measured and relating factors which were affected noise level were investigated. The results were as follows ; 1. The noise levels were $88.70{\pm}5.68dB(A)$ by SPL, $89.07{\pm}5.41dB(A)$ by Leq and $89.07{\pm}5.69$ by Dose. The differences of noise levels by three measuring methods were statistically significant(P<0.001) by repeated measure ANOV A. 2. Comparing with noise levels by general classes of noise exposure, noise levels of continuous noise were $89.14{\pm}5.19dB(A)$ by SPL, $89.45{\pm}4.65dB(A)$ by Leq and $90.04{\pm}5.09$ by Dose. Noise levels of intermittent noise were $87.90{\pm}6.52dB(A)$ by SPL, $88.40{\pm}6.63dB(A)$ by Leq and $90.10{\pm}6.80$ by Dose. The differences noise level of noise measuring methods by general classese of noise exposure were statistically not significant by repeated measure ANOV A. 3. Interaction between general classese of noise exposure and noise measuring methods for noise level was not statistically significant by repeated measure ANOVA. And the noise level by noise measuring methods were statistically significant by repeated measure ANOV A(P<.001) 4. Comparing with noise levels by unit workplace size, noise levels of large unit workplace were $90.73{\pm}5.87dB(A)$ by SPL, $91.32{\pm}5.50dB(A)$ by Leq and $91.82{\pm}6.06$ by Dose and noise levels of middle unit workplace were $88.31{\pm}5.26dB(A)$ by SPL, $88.41{\pm}4.83dB(A)$ by Leq and $89.69{\pm}5.05$ by Dose. And noise levels of small unit workplace were $94.89{\pm}4.10dB(A)$ by SPL, $85.35{\pm}4.11dB(A)$ by Leq and $86.87{\pm}4.98$ by Dose. The noise level differences of noise measuring methods by unit workplace size were statistically significant by repeated measure ANOV A(P<.05). 5. The noise level by noise measuring methods were statistically significant by repeated measure ANOV A(P<.001). But Interaction between workplace size and noise level measuring methods for noise level was not statistically significant by repeated measure ANOVA. According to the above results, there was a difference of the noise level among the three measuring methods. Therefore we must use the personal noise exposure dose using by noise dose meter, possible, to prvent occupational hearing loss in noisy working environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.480-483
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• 2007

Recently, many apartment houses were built in nearby road and railway. Road traffic noise level and railroad traffic noise level are important factors on apartment houses inhabitant's acoustic comforts. The measurement methods which noted by Ministry of Construction & Transportation, Ministry of Environment and Korean Industrial Standard are used for measurement of exterior noise at apartment houses. The purpose of this study compare the noise level characteristic by the measuring methods and evaluating methods. The results show that road traffic noise in the daytime appeared by not greatly noise level difference by the measuring method and evaluating methods. But railroad traffic noise appeared by greatly the noise level difference by the equivalent noise level(1hour) and continuous time.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.31-42
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• 2013

PURPOSES : The purpose of this study is to eliminate the noise of the vehicle after measuring the friction noise obtained from the NCPX (Noble Close ProXimity) method. The pure friction noise between the tire and road pavement could be determined from filtering the compositeness of sound and the influence of the vehicle noise. METHODS: The noise magnitude could be determined by analyzing the sound pressure level (SPL) and sound power level (PWL) along with the noise frequency of a FFT (Fast Fourier Transform) analysis as well as CPB (Constant Percentage Bandwidth) analysis. RESULTS: When the test for measuring the friction noise originated somewhere between tire and road pavement is performed with NCPX method, it must be fulfilled by attaching the surface microphone near the tire. In this condition, the surface microphone can measure the friction noise occurred at between tire and pavement, the chassis noise from the engine and power transfer units, the fluctuating aerodynamic noise, and the turbulence noise directly affected to the surface microphone. By using the NCPX method, the noise occurred at the vehicle must be eliminated for measuring the friction noise between tire and pavement from the traffic noise. CONCLUSIONS: The vehicle's testing engine noise depends on the vehicle and road types. The effect of vehicle's engine noise is less than the friction noise occurred at between tire and pavement at less than 1% effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.703-706
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• 2001

Currently domestic criteria for the aircraft noise is being adapted WECPNL(weighted equivalent continuous perceived noise level), while internationally preferred method is which is originated from $L_{eq}$ and can evaluate even environmental noise. WECPNL used in domestic as a evaluation method is only for the aircraft noise. It is, therefore, not adequate for the evaluation of residents' injury, moreover, it is very difficult to measure the aircraft noise with WECPNL due to the complicated calculating procedures as long as automatic measuring system is not used. Accordingly, this study aims to propose alternative evaluation method for the aircraft noise. To achieve this purpose, the data measured by automatic measuring system were gathered and calculated with three evaluation methods： WECPNL, $L_{eq}$ and $L_{dn}$ and the results calculated from different methods were compared and analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.424-432
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• 2000

The revision was provided for the method of A-weighted sound pressure measurement for fans and blowers, in which the newly developed measurement techniques were applied to KS B 6361. This revision includes the sound power methods for radiated sound from the body, the in-duct measurement method, and the correction method for flow noise upon measuring microphone, etc.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.201-206
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• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.631-635
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• 2006

In this study, simplified methods on measurement and evaluation of heavy-wight impact sound was proposed due to provide easy quality control method to construction engineers. The simplified methods include using of rubber impact ball instead of bang machine, reduced number of measuring and impact positions which is prescribed as over 4 points, using of hand-held sound level meter as a frequency analyser and prediction equation for $L_{i.Fmax.AW}$, single number rating, using $L_{Amax}$, and $L_{Lmax}$ at each frequency band. The results showed that a method of boundary driving and boundary measuring is the most similar to the current rating method.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.11-18
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• 2013

PURPOSES : This study presents the noise level and frequency characteristics investigated in the national highways with the consideration of various measuring conditions and/or methods. METHODS : The noise levels on the asphalt concrete pavement(ACP) and the jointed plain concrete pavement(JPCP) of the national highway were measured and analysed with respect to three variables, i.e., pavement type, surface condition, and measurement distance. The PASS-By method is utilized for the noise measurement and then using CPB spectrum analysis method with 1/3 octave bandwidth, the noise levels and frequency characteristics were calculated for two-second periods before and after the peak noise. RESULTS : Depending on the pavement type, the noise level was changed as the average noise levels are 73.3dB(A) and 78.3dB(A) for ACP and JPCP, respectively. With respect to the effect of surface condition, the average noise levels for crack H(high), M(medium), and L (low) sections are 77.4dB(A), 77.4dB(A), and 78.1dB(A), respectively. Regarding the measurement distance, 1.2meter difference in measuring location reduces 1.6dB(A) of noise level; the average noise levels at 5.3m and 7.5m from the centerline of outer lane are 72.8dB(A) and 71.2dB(A), respectively. It should be noted that the noise levels are slightly different as a function of vehicle speed and type. However, the overall trends for each case was similar. It was found that the domain frequency bands for ACP and JPCP were 400Hz~2000Hz and 500Hz~2000Hz, respectively. CONCLUSIONS : Based on the analysis with the measured noise date from national highway, it was concluded that the noise level and frequency band vary depending on the various conditions. It was also found that some variables significantly affect the noise level while others do not. With further systematic investigation, the comprehensive noise characteristics on the national highway can be achieved. Using such database, it is possible to develop the fundamental noise reduction technology.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.6
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• pp.420-430
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• 2002

Rating scales for environmental noise are varied in their calculation procedure. Among them WECPNL (weighted equivalent continuous perceived noise level) is the rating scale for aircraft noise currently being used in domestic and applied only for aircraft noise. However $L_{dn}$ calculated from $L_{eq}$ $L_{eq}$ is used as a rating scale for not only aircraft noise but also environmental noise. Besides, it is easy to calculate and internationally preferred. It is, therefore, not adequate for the evaluation of residents' exposure. Moreover it is very difficult to measure the aircraft noise by WECPNL due to the complicated calculating procedures if automatic measuring system is not used. Accordingly. this study aims to propose alternative evaluation procedure for the aircraft noise. To achieve this purpose, the data measured by automatic measuring system were gathered and calculated with three evaluation procedures : WECPNL $L_{eq}$ and $L_{dn}$, and the results calculated from different methods were compared and analyzed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.841-849
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• 2013

Workers engaged in construction works have been exposed to high levels of noise during their work in tunnels. Noise is one of the major health hazards for employees working in construction sites. The aim of this study is to evaluate the noise levels generating from tunneling equipments such as jumbo drills, backhoes, payloaders, shotcrete machines and service cars. Explosion and turbo fan noises were also monitored. A high precision sound level meter was introduced for measuring LAeq, LAFmax, LAFmin and LCpeak noises in 5 tunneling work sites that were located in Seoul, Kyunggi-do and Kangwon-do areas with NATM and shield methods. The highest noise was recorded by explosion(151.9 dB LCpeak) followed by jumbo drills of higher than 110 dB(A) LAeq. Backhoe normally generated 90~110 dB(A) LAeq while breaking work of rock showed additional around 5~15 dB(A). Noise exposure levels for payloader and shotcrete machine scored more than 90 dB(A) which might be a source of noise-induced hearing loss. Additional research in revealing noise levels from construction equipments operating in tunneling works may enhance the protection of workers who exposed to noise primarily at the sites.