• International Journal of Highway Engineering
• /
• v.18 no.5
• /
• pp.31-37
• /
• 2016

PURPOSES : The purpose of this study is to evaluate the effect of the quiet pavement on reducing a barrier height by using a prediction tool called SoundPLAN. METHODS : Firstly, the prediction was carried out to evaluate the difference in the maximum noise level at a building facade between the normal and the quiet pavements without a barrier. After calculating the noise reduction effect by the quiet pavement, a comparable barrier height to obtain the same noise reduction effect with it was predicted according to designable factors including road-building distance(10 m, 20 m, 40 m) and road-barrier distance(5 m, 10 m, 20 m, 30 m). RESULTS : The result showed that within the considered designable factors, the maximum barrier height was 37 m, 52 m, and 55 m to have the same noise reduction effect by the quiet pavement reducing 1 dBA, 3 dBA, and 5 dBA, respectively. It was evaluated that the barrier height increased with the increase of the road-building and road-barrier distances. To simulate the real situation in urban areas and to evaluate the combined effect of the normal/quiet pavement and barrier, the barrier height was fixed as 6 m. It was predicted that the noise level would reduce to as low as 0.2 dBA by the combination of normal pavement and barrier. On the other hand, the combination of the quiet pavement and barrier reduced 1.2 dBA, 3.2 dBA, and 5.2 dBA, respectively, for quiet pavement reducing 1 dBA, 3 dBA, and 5 dBA. CONCLUSIONS : A guideline needs to be suggested to select appropriate noise abatement schemes by considering factors such as the roadbuilding and road-barrier distances.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.12
• /
• pp.27-33
• /
• 2016

In this paper, we propose the bilateral filter based on median value that can reduce random noise and impulse noise with minimal loss of contour information. In general, EO / IR camera to generate a random or impulse noise due to a number of reasons. This noise reduces the performance of detecting and tracking by signal processing. To reduce noise, our proposed bilateral filter sorts the values of the target pixel and the peripheral pixels, and extracts a median filter coefficients of the Gaussian type. Then to extract the Gaussian filter coefficient involved with the distance between the center pixel and the surrounding pixels. As using those filter coefficients, our proposed method can remove the various noise effectively while minimizing the loss of the contour information. To validate our proposed method, we present experimental results for several IR images.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.44 no.5
• /
• pp.49-56
• /
• 2007

In the sensor networks, the first step in the signal processing is noise reduction. It is obvious that the noise in the sensing data by sensor nodes have a bad effect on the collaborative signal processing results. In this paper we propose noise reduction filters for the wireless sensor networks. The proposed filters use only relative distance information between sensor nodes thus it is very simple in complexity and easy to implement. Also it will be able to extend the sensor network life time by adjusting communication radius of sensors within proper limit to reduce consuming power. Various simulation results are presented to verify our approaches, we observed that the proposed filters can reduce the effect of the noise on the sensing data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1415-1418
• /
• 2007

When a high voltage COS fuse becomes a short circuit by the over current, the impulse noise over 150 dB(A) with the strong pulse jet is radiated from the COS fuse of an electric transformer. For the purpose of the impulse noise reduction, in this study, a reactive type silencer with perforated panels are considered. The transmission loss of the silencer are calculated by transfer matrix method. The effect of the porosity, the distance between panels, and the number of perforated panel on the sound transmission loss is investigated and discussed.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.562-564
• /
• 2002

Noise reduction and a simplification of a precision measurement system has been performed by changing analog output mode of a load cell into digital output mode. Usually, analog output signal of a few $\mu V$ from a load cell are amplified by amp and acquired by A/D converter. If the distance from a load cell to a DAS(Data Acquisition System) increases, more noise signals are mixed. So, a microprocessor has been integrated into a load cell so that the amplification and A/D conversion of output signals could be done in close proximity to the lode cell for the reduction in mixing of noise. Obtained data from the load cell like this manner are transferred to a computer with digital values(of TTL level). To simplify the configuration of a multi-channel DAS, RS-485 communication system has used for data transfer.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.12
• /
• pp.1871-1876
• /
• 2010

The reduction of vehicle interior noise has been the main interest of NVH engineers. The driver's perception of the vehicle noise is strongly affected by the psychoacoustic characteristics of the noise and the SPL. The existing methods to evaluate the SQ for vehicle interior noise are linear regression analysis of subjective SQ metrics by statistics and the estimation of subjective SQ values by neural network. However, these methods strongly depend on jury tests, this leads to difficulties. To reduce the important of the jury tests, we suggest a new method using the Mahalanobis distance for SQ evaluation. And, the optimal characteristic values that influenced the results of sound quality evaluation on the basis by main effect. Finally, we developed a new method based on the MD method to evaluate sound quality. The result of noise evaluation revealed that the sound quality could be well improved by changing the structural characteristics of the vehicle.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.5
• /
• pp.649-655
• /
• 2022

In this paper, a determinant-based two-channel noise reduction method which utilizes speech presence probability (SPP) is proposed. The proposed method improves noise reduction performance from the conventional determinant-based two-channel noise reduction method in [7] by applying SPP to the Wiener filter gain. Consequently, the proposed method adaptively controls the amount of noise reduction depending on the SPP. For performance evaluation, the segmental signal-to-noise ratio (SNR), the perceptual evaluation of speech quality, the short time objective intelligibility, and the log spectral distance were measured in the simulated noisy environments considered various types of noise, reverberation, SNR, and the direction and number of noise sources. The experimental results presented that determinant-based methods outperform phase difference-based methods in most cases. In particular, the proposed method achieved the best noise reduction performance maintaining minimum speech distortion.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.4
• /
• pp.393-399
• /
• 2008

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. The previous methods to evaluation of the SQ about vehicle interior noise are linear regression analysis of subjective SQ metrics by statistics and the estimation of the subjective SQ values by neural network. But these are so depended on jury test very much that they result in many difficulties. So, to reduce jury test weight, we suggested a new method using Mahalanobis distance for SQ evaluation. And, optimal characteristic values influenced on the result of the SQ evaluation were derived by signal to noise ratio(SN ratio) of the Taguchi method. Finally, the new method to evaluate SQ is constructed using Mahalanobis-Taguchi system(MTS). Furthermore, the MTS method for SQ evaluation was compared by the result of SQ grade table at the previous study and their virtues and faults introduced.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.1
• /
• pp.51-56
• /
• 2013

This paper is the experimental study to investigate the noise sources location in order to reduce the noise level of line flow fan for the air conditioner in the subway car. The noise of line flow fan is caused by various factors such as the turbulence by air flow, random noise, noise of blade passing frequence(681Hz) and noise due to structural vibration of rotor unbalance(28.4Hz) by motor revolution. By performing the noise reduction on each sound source, the noise level is decreased as much as 5.7dB(A) through the controls of housing guide angle and distance, the configuration changes of flow passage shape and rotor balancing.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.2
• /
• pp.165-170
• /
• 2009

Pressure ripple, vibration and noise level are measured in each parts of the power steering system. MD(Mahalanobis Distance) is calculated by using MTS(Mahalanobis Taguchi System) with measured data, and noise sensitive components are selected. The components applied detail design parameters are made and data is measured. After that MD is calculated also. Mean value and SN ratio can be obtained from the MD. Effective noise reduction technique and dominant design parameters in hydraulic power steering system are introduced.