• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.357.1-357
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• 2002

The purpose of this study is to propose indoor noise level in residential buildings affected by transportation noise (road traffic, railway and air-craft noise) based on subjective evaluations. 30 subjects participated in the experiment to evaluate the noise. Experimental environment reproduced real living and office environment, and in asking subjects' annoyance to the noise. (omitted)

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.487-494
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• 1999

The object of this study is to reduce the subway noise by the low noise wheel. The vibro-acoustic reduction was predicted from the FRF difference between low noise wheel and solid wheel by experimental modal analysis. The low noise wheel and solid wheel were compared in viewpoint of car interior/exterior noise. The effect of low noise wheel on the noise of subway train of 6 vehicles was obtained. But, the application of low noise wheel must be reviewed in some aspect.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.150-157
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• 2011

Nowadays, high speed train has settled down as a fast and convenient environment-friendly transportation and it's need is gradually increasing. However increased train speed leads to increased aerodynamic noise, which causes critically affects comfortability of passengers. Especially, the pantograph of high speed train is protruded out of train body, which is the main factor for increased aerodynamic noise. Since aerodynamic noise caused pantograph should be measured in high speed, it is difficult to measure it and to analysis aerodynamic noise characteristics due to the various types of pantograph. In this research, aerodynamic noise of pantograph is predicted by CFD (Computational Fluid Dynamic) and FW-H (Ffowcs Williams-Hawkings) equation. Also, Wind tunnel test results and numerical simulation results were compared. As a result, Simulation results predicting sound pressure level is very similar with wind tunnel test result. This research will draw major factor in aerodynamic noise of pantograph and will be utilized for predict sound pressure level of pantograph.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.662-663
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• 2014

In most vehicle manufactures have traditionally relied on find-fix method of human auditor, mainly due to variation excitation source. To solve the BSR noise, the requirements for BSR test are presented in terms of detection of noise source, analysis of time-frequency and sound pressure, sound quality for noise. A number of new technology direction, particularly in the field of noise source identification application and psycho-acoustics from the Zwicker's sound quality parameter, the computed objective sound metrics and subjective jury test result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.714-720
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• 2008

This research presents a laboratory study about an subjective response of 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. In the result of the jury test for impulsive noise, the mean response rating expressed a linear relation and %HA(percent highly annoyed) displayed a exponential growth relation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.2
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• pp.108-115
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• 2003

High pressure hose having tuning cables, called Resonator hose is frequently used to attenuate pressure ripple generated by the pump for reducing the vehicle interior noise. A number of studios have been conducted on the resonator hose and its analytical models. However, there are few studies which deal with the influence of resonator hose on vehicle interior noise because the most of studies were focused on transmission loss of the resonator hose. This paper presents NVH test results of power steering system and frequency analysis results. In the frequency analysis, both the relations between vibration, pressure ripple and vehicle interior noise and also the design parameters of high pressure hose influencing on vehicle Interior noise were discussed. The test was done for various high pressure hose specimens in full turn condition.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.100-107
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• 1999

In this paper, we deal with the speckle noise reduction and parameter estimation of ultrasonic NDT(non-destructive test) signals obtained during weld inspection of piping. The overall approach consists of three major steps, namely, speckle noise analysis, proposition of wavelet domain AR(autoregressive) model and flaw detection by proposed model parameter. The data are first processed whereby signals obtained using vertical and angle beam transducer. Correlation properties of speckle noise are then analyzed using multiresolution analysis in wavelet domain. The parameter estimation curve obtained using the proposed model is classified a flaw in weld region where is contaminated by severe speckle noise and also clear flaw signal is obtained through CA-CFAR threshold estimator that is a nonlinear post-processing method for removing the noise from reconstructed ultrasonic signal.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1067-1073
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• 2006

In this paper, we present noise measurement results of 8 vehicles. The measurement was done by a close proximity method attaching surface microphones on the test vehicle. For the 9 road surface types constructed at Korean highway test road, the vehicles were tested from 50 to 120 km/h at the interval of 10 km/h in normal steady state and inertia cruising conditions. Using the results, we evaluate and discuss the effect of vehicle noise generation depending on the different conditions for vehicle type, speed, road surface and loading condition, especially focused on friction noise between tyre and road surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.428-433
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• 2006

In this paper, we present noise measurement results of 8 vehicles. The measurement was done by a close proximity method attaching surface microphones on the test vehicle. For the 9 road surface types constructed at Korean highway test road, the vehicles were tested from 50 to 120 km/h at the interval of 10 km/h in normal steady state and inertia cruising conditions. Using the results, we evaluate and discuss the effect of vehicle noise generation depending on the different conditions for vehicle type, speed, road surface and loading condition, especially focused on friction noise between tyre and road surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.513-516
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• 2004

Consistency in design, manufacture, installation and performance test of expansion joints is insufficient for guarantee of reliability because they are imported from various foreign countries as America, Japan and Europe. In addition to that, the regulations or codes of expansion joint should be revised and established for levels of vibration and noise generated from riding vehicles especially. Regulation on the noise neighboring traffic roads is established by ministry of environment. Therefore, Field tests on the vibration and the noise at expansion Joints, especially rail-type and finger-type joints which are typical ones in bridge with short or middle span, are performed and performance of expansion joints are analyzed. And so, the results of the investigation will be utilized as basic data for the regulation on the vibration and the noise.