• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.297-302
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• 2007

Recently, electrical resistivity survey is used in the various fields and applied to urban area with many electrical noises. Therefor it's necessary to observe the electrical noise effect of the geological structure. The physical scale modeling was conducted for measuring the electric noise effect of the two geological models at various distances, depths and diameters of the electric noise objects. The results are as following. 1. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various separated distances to the measurement line was disappeared at a half distance measurement line length regardless of electrode arrays. 2. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various depths was disappeared at 4unit apart from the measurement line regardless of electrode arrays. 3. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various diameters was disappeared at 4unit apart from the measurement line regardless of electrode arrays.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.56-62
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• 2003

The major noise source for the conventional train is the rolling noise caused by the interaction of the wheels and rails during the train passage on the tangent track. In order to control the rolling noise, the noise radiated from wheels, rails and sleepers should be analyzed and predicted. In this paper, a prediction method of wheel/rail rolling noise generated by the roughness of the wheel/rail surface is described, where the method is considering the effect of noise radiated by sleepers and the effect of ground. The method is applied to the Korean railway system, and the sound pressure level (SPL) predicted by the proposed method is compared with the measured SPL. Overall. the result shows good agreement between the predicted and measured values.

• Journal of KSNVE
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• v.10 no.4
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• pp.629-635
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• 2000

Wheel /rail interaction has been known as a major source of railway noise. In this paper, a low noise wheel structure is developed and its effect on noise reduction is investigated. The developed low noise wheel employees a rubber material inserted into a steel rim or mounted on the wheel surface. Since the low noise wheel has low stiffness and high damping ratio compared to a solid wheel, the measurement results show that it reduces the rolling and squeal noise. It turns out that the proposed wheel could reduce interior noise level by 4∼5dB(A) and vehicle vibration level by 7∼10 dB. Although the proposed structure seems to be promising in noise reduction of railway vehicles, the low noise wheel is to be verified in endurance and cost effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.202-207
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• 2003

The purpose of this study was to investigate the effect of background noise on loudness magnitude estimation of Heavy-weight impact noise. Relationship between loudness magnitude estimation and estimation methods about floor impact noise had appeared low in apartment which receive much effect of background noise. Then, to need new estimation method abut effect of background noise. Masking effects by background noise is increased steadily, there is a continuous transition between an audible impact noise and one that is totally masked. Result 1 hat analyze interrelationship of phychoacoustical data and values through Zwicker Parameters, to Investigate that an estimation experiment about Annoyance need.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.303-310
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• 2008

In Korea, the current noise impact assessment has not yet considered the vertical noise propagation property by buildings and other obstacles. And noise control plan has been established without conducting the economic assessment for the noise control facilities. A noise map is used to calculate the noise level based on a theoretical formula or an empirical formula, and also predict the characteristics of vertical propagation by linking with a geometry data. And It is Possible to analyze cost-effect of noise control facilities by consider installation costs. In this study, we addressed the application of noise map for noise impact assessment and cost-effect analysis of noise control facilities.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.381-387
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• 2003

Engine noise consists of the noise radiated from an engine structure and noises from engine ancillaries such as a turbocharger fuel injection system, and alternator. The noise of these ancillaries might be incorrectly evaluated in the aspect of the noise contribution to engine noise because the noise reflection effect of their neighbor engine structure is easily ignored. Consequently, noise source identification should be misled. This study investigates the fact that the engine structure located around an alternator reflects alternator noise, and the reflected noise acts as another alternator noise source in a heavy-duty diesel engine. The result shows that the alternator noise can be correctly estimated in engine noise by properly including the noise reflection effect.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.960-966
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• 2009

The World Health Organization(WHO) has reported the sleep disturbance as one of the adverse effects of noise. And the effect of combined noise sources on human have been investigated because community noises are seldom heard and are concurrent. Therefore, the effects of combined noise source and its S/N ratio on sleep disturbance were investigated; as a single noise source, road traffic noise was selected, and construction and movie noise were combined with road traffic noise. Tests for sleep disturbance were conducted in bedrooms and the effect on each subjects' sleep was evaluated by questionnaire. The results showed that the rate of awakening increased slightly only when the SPL of construction noise was 10 dB higher than that of road traffic noise. It was also found that the sleep disturbance was affected by the type of combined noise sources and its S/N ratio.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.483-488
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• 2008

The exhaust system, including a muffler, is one of the major sources to generate the radiated noise of construction equipment. In general, the muffler is applied to construction equipment in order to reduce the exhaust noise. Sometimes, however, the higher exhaust noise can be experienced due to the flow effect inside a muffler. So, it is required to consider the flow effect to reduce the exhaust noise level of construction equipment. In this paper, various tests were performed to calculate the flow noise effect inside a muffler. Through a series of tests with respect to a variety of design parameters, a new design program for low noise muffler was developed and applied to reduce the exhaust noise of the construction equipments. These results make it possible to understand the dynamic characteristics of the flow noise and to design the low noise muffler for the construction equipments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1045-1049
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• 2001

Before building houses or apartments, we need to predict noise propagation to eliminate possible noise problems to residents. However, we do not try to predict noise propagation during estimation of noise effect for the developing area since we did not have a good mathematical model to predict noise level due to a traffic noise. In this article, an adequate mathematical model has been developed and proved to predict noise effect to living area due to a traffic noise.