• 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.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.52-59
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• 2015

In the conventional model for the prediction of the railway environmental noise, one used an empirical formula of the total noise level at specific distances. Only a function of the distance to the source was also used to calculate the noise level near the railway bridges. However, the noise varies depending on the position of the receiver as well as the distance from the source especially at concrete bridges. In this paper, a noise propagation model in the railway concrete bridge was derived by considering the diffraction at the bridge deck and the ground effect and applying the ISO 9613-2 noise propagation model. We compared the predicted and measured values of environmental noise at a high-speed railway bridge, and it was confirmed that this prediction model gives relatively small errors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.5-8
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• 2008

Apartment housing is a widely-spread type in Korean housing market. Nevertheless, it has caused serious problems such as traditional community corruption, unsafe structure, defects and litigation from noise. Noise, especially in concrete structure for apartment housing, is hardly controlled in proper to prevent sound transmission between upper and lower families with existing system, In foreign countries, there are floating floor systems to enhance the noise control performance in multi-family housing. Therefore, this study aims to analyze subjective responses on sound characteristics in residential buildings. We analyzed the residential response and the quantities of measured data from environmental noise. The results of this study will be useful to provide guideline to make policy of environmental noise and criteria.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.502-507
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• 2011

A study on environmental noise hasn't fully researched yet. As society has developed and the quality of life has improved, people started to show a concern about an environmental noise. To ensure a economic feasibility of countermeasures of noise, it is necessary to apply a cost-benefit analysis on choosing optimum measurements. In this study, we addressed the estimation method of the environmental noise value and several domestic and oversea case studies. We also estimate economic value of noise reduction level which is gained from applying noise reduction measurements.

• Journal of Environmental Impact Assessment
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• v.32 no.5
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• pp.279-290
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• 2023

Recently, as wind farms using wind power as new and renewable energy have been installed nationwide, noise problems have emerged. The environmental impact assessment and post-environmental impact assessment also require the measurement of background noise and low-frequency noise for wind farms, especially by applying the living noise measurement method according to the low-frequency noise management guidelines issued by the Ministry of Environment in 2018. Due to the nature of wind power generators that generate loud noise in high winds, noise measurement should be made at high winds, but when wind speed increases, wind noise increases and living noise and low-frequency noise are not properly evaluated. Therefore, the type of noise generated by wind power generators was confirmed, and matters to be considered when measuring wind noise such as wind noise were confirmed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.499-504
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• 2012

The high-speed train enjoys widespread acceptance as environment-friendly means of medium- to long-distance transportation. The pursuit of higher speed and lighter weight in railroad vehicles has engendered higher noise level. In particular, the environmental noise places many restrictions in the operation of high-speed railroad vehicles. This research investigates the effect of installing a skirt onto a high-speed train bogie with the top speed of 400 km/hr and using High Speed EMU for the purpose of reducing the environmental noise. In order to analyze the effect of the interior noise and environmental noise due to installation of the skirt, sound level is calculated using the Ray method and Statical Energy Analysis method. The numerical calculation predicts a reduction of approximately 2 dB in the environmental noise level, but at the cost of increase of approximately 2.5 dB in the interior noise level of the vehicle.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.727-729
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• 2002

In this paper, we proposed quad variable rates ADPCM coding method and its implementation on C6000 DSP, which is modified from the standard ADPCM of ITU G.726 for speech quality improvement considering the environmental noise Four coding rates, 16Kbps, 24Kbps, 32Kbps and 40Kbps are used for speech window samples and the rate decision threshold is decided by the environmental noise level. The object of the proposed method is to reduce the coding rate while retaining the speech quality and the speech quality is considerably close to 40Kbps single rate coder with the coding rate close to 16Kbps single rate coder under the environmental noise. The environmental noise level affects the coding rate and the noise level is calculated per every speech window samples. At high noise level, more samples are coded at higher rates to enhance the quality, but at low noise level, only the big speech signals are coded at higher rates and more speech samples are coded at lower coding rates to reduce the coding rates. The influence of the noise on tile speech signal is considerably high for small signals and the small signal has the higher ZCR (zero crossing rate). The method is simulated in PC and to be implemented on C6000 floating point DSP board in real time operations.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.99-105
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• 2007

Since 1990s, the railway noise has been researched and developed in our nation. First of all, what's causing the noise and how to eliminate the cause of the noise must be found out. Secondly, cutting off the propagation path of the noise from the noise source to the receiving points. In this study the characteristics of prediction formula for the assessment of railway noise used in some nations including Korea were investigated. In order to develop the prediction formula of the railway noise, the noise radiated from railway vehicle, rails and sleepers, characteristics of noise barrier, velocity of train, ground effects, roughness should be analyzed and predicted. Especially, on the basis of acoustics, the characteristics of source are applied to acoustic power and directivity information.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.345-349
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• 2008

In this paper, environmental noise analysis was performed for large power plant and desalination plant. Ray tracing method was used to predict inside noise of turbine building. It is important to design the plant with the allowable noise level. To improve the accuracy, main noise sources were estimated based on the field data. As the results of analysis, it was concluded that noise levels slightly exceed the specified noise limit in turbine building inside. In order to reduce the noise level, adding sound-absorbing materials to inside wall of turbine building was suggested and verified with the confirmed analysis model.

• Journal of Environmental Impact Assessment
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• v.10 no.4
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• pp.297-304
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• 2001

Recently the road traffic noise has appeared as a significant environmental issue because of dramatic increase of vehicles and expansion of newly constructed road. Therefore, this study proposes the method that improves prediction factors and models through analysis of the existing road traffic noise prediction model. Prediction factors can be improved by establishing guideline for diffraction attenuation and applying daily traffic discharge, peak traffic discharge, and average traveling speed through an analysis of level service. Prediction must be made by periods of one or five years during 20 years. Prediction models also can be improved to include better prediction model through setting the database, establishing functional relation between physical properties and noise levels by acoustic analysis, and developing models for road traffic noise prediction in residential areas.