• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.650-656
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• 2011

The noise inside a naval vessel is very important in considering the need for hearing protection, improving the working environment and maintaining good communications for crews living on board a naval vessel. The indoor noise of a ship usually is specified by the A-weighted sound pressure level, but other evaluating parameters are required to reflect human senses more effectively. This paper uses additional noise indices related to room acoustics, such as NR(noise rating), NC(noise criterion), RC(room criterion), PSIL(preferred speech interference level) and loudness level to evaluate the noise inside cabins on a naval vessel. Using these psychological noise indices, allowable limit of noise level in cabins is suggested through psycho-acoustic evaluation for the noise in cabins.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.73-80
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• 1987

Various procedures for evaluation of traffic noise annoyance have been proposed. However, most of the studies of this type are restricted for improving traffic flow. In this paper, a method to predict the road traffic noise is proposed in terms of equivalent continuous A-Weighted sound pressure level (Leq), based on a probability model. First, distribution of the road traffic noise level are investigated. second, the weibull distribution parameters are estimated by using the quantification theory. Finally, a prediction model of the road traffic noise is proposed based on the weibull distribution model The predicted values of the Leq are closely matched the measured data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.8
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• pp.694-701
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• 2018

Civil aircraft noise certification standard is based on the ICAO Annex 16 Vol. 1. And, the standard uses A-Weighted SPL, EPNL and SEL method depending on the aircraft category. Korean noise standards, KAS 36 and other nation's CS 36 and FAR 36 noise standards were developed and revised according to the international noise standards, ICAO Annex 16. And, the national noise requirements are equivalent each other. The small airplane noise certification requires only take-off noise level with A-Weighted SPL in dB(A) unit. The first Korean aircraft noise certification was performed for the KC-100 certification in August 2012 with Korean authority and U.S. FAA. The noise certification requires much knowledge and experience in flight tests and noise data processing. In this study, the noise test requirements, test conditions and data correcting methods are shown with the test examples.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.374-385
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• 2012

The indoor noise of a ship is usually determined using the A-weighted sound pressure level. However, in order to better understand this phenomenon, evaluation parameters that more accurately reflect the human sense of hearing are required. To find the level of the satisfaction index of the noise inside a naval vessel such as "Loudness" and "Annoyance", psycho-acoustic evaluation of various sound recordings from the naval vessel was performed in a laboratory. The objective of this paper is to develop a single index of "Loudness" and "Annoyance" for noise inside a naval vessel according to a psycho-acoustic evaluation by using psychological responses such as Noise Rating (NR), Noise Criterion (NC), Room Criterion (RC), Preferred Speech Interference Level (PSIL) and loudness level. Additionally, in order to determine a single index of satisfaction for noise such as "Loudness" and "Annoyance", with respect to a human's sense of hearing, a back-propagation neural network is applied.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.348-356
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• 2014

To understand the relationship between road-traffic noise and urban components such as population, building, road-traffic and land-use, the city of Cheongju that already has road-traffic noise maps of daytime and nighttime was selected for this study. The whole area of the city is divided into square cells of a uniform size and for each cell, the urban components are estimated. A spatial representative noise level for each cell is determined by averaging out population-weighted facade noise levels for noise exposure population within the cell during nighttime. The relationship between the representative noise level and the urban components is statistically modeled at the cell level. Specially, we introduce a spatial auto regressive model and a spatial error model that turns out to explain above 85 % of the noise level. These findings and modeling methods can be used as a preliminary tool for environmental planning and urban design in modern cities in consideration of noise exposure.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.668-673
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• 1994

The paper presents a simple method for calculating the sound exposure level (LAE) of helicopter noise. It is assumed that a helicopter is a nondirective point source and that A-weighted sound pressure level at an observation point can be expressed by an A-weighted power level and a simple function of the distance from the helicopter. We derived a formula for LAE by integrating the sound energy along a finite or an infinite flight segment. The values calculated form the formula agree well with the results of test flights in which three types of helicopters each were operated in three moving modes of approach, takeoff and level flyover.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.727-734
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• 2008

This research presents a laboratory study about difference of subjective response between with and without pictures. A main source is impulsive sound caused by leisure shooting. The sources are sampled from outdoor noise and their levels range from 40 to 75 dB at the interval of 5dB. The noise unit is based on A-weighted sound exposure level (ASEL; $L_{AE}$). To make equal ASEL of outdoor noise, finite impulse response (FIR) filter is applied to the originally sampled source to include the effect of distance attenuation. The evaluation method of the jury test adopted a Semantic Difference(SD) Method. The intersection point which two lines crossed was used as reference point. The intersecting point of mean response rating between with and without pictures was approximately 44ASEL and that of %HA was about 60ASEL. In the result of the test, the negative effect of pictures was given at a lower levels than intersection point while the positive effect was given at a higher levels than that.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.273-278
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• 2002

Booming sound is one of the most important interior sound of a passenger car. The conventional booming noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level can not give the whole story about the booming sound of a passenger car. In this paper, we employed sound metric which is the subjective parameter used in psycoacoustics. According to recent research results, the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network theory has been applied to derivation of sound quality index for booming sound of a passenger car.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.628-634
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• 2003

Rumbling sound is one of the most important interior sound of a passenger cu. The conventional rumbling noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level can not give the whole story about the rumbling sound of a passenger car. In this paper, we employed sound metric which is the subjective parameter used in psycoacoustics. According to recent research results, the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network th[ ory has been applied to derivation of sound quality index fur rumbling sound of a passenger car.