• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.829-835
• /
• 2001

The sources of wayside noise for the high speed train are the aerodynamic noise, rolling noise and power unit noise. One of the best ways to control the wayside noise is to analysis the noise level. In this paper, we measure the wayside noise and the vibration of the rail/sleeper for Korean Train Express (KTX) and compare with the results for the conventional train. The measurement results for KTX show that the characteristics of the noise and vibration are different from the conventional train and the rolling noise and power unit noise are the major sources.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.387-392
• /
• 2003

This study is put a focus on the identification of sound characteristics according to the interior configuration of sound absorption material and air gap. Noise barrier is general consists of front perforated panel, air layer, sound absorption material, air gap and back plate. Noise barrier is required to the NRC value of 0.7. The absorbing performance of the noise barrier relies on the opening ratio of the perforated panel and the efficiency of the absorbing material. This study has observed the effect of opening ratio and hole size, the increase of sound absorbing performance by the configurations of sound absorption material and air gap. New designed noise barrier is achieved the acoustical performance of 0.87 the measurement in a reveration room.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.6 no.2
• /
• pp.67-75
• /
• 1997

The noise . vibration characteristics of Hypoid gears which were made from three seperate materials(SCM, TSCM, SNCM) under the identical process were investigated for the sake of durability improvement of differential gear compatible with low level noise gear set. For this study, we developed a rig experimental equipment which can perform close noise.vibration experiment of differential gear. Consequently, we could analyze the noise.vibration characteristics of final reduction gear by materials, and also we observed changes in both metallic structure and hardness according to the materials of pinion gear. In addition to this, the correlation between the vibration of the differential gear and the interior noise of the passenger vehicles was proved by analyzing the results of rig vibration experiment and field noise test.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.49-55
• /
• 2006

The purpose of the present study is to analyse characteristics of the background noise for the broadband seismic stations in KMA. It is well known that the background noise arises continuously from long period microseism, sea waves, minute changes of atmospheric pressure, seasonal temperature change of the ground surface, culture activities, and etc. The background noise shows spatial and temporal changes and it has various characteristics such as its spectral amplitudes in frequency domain are not constant Such the background noise gives considerable influences on the quality of seismic record. To investigate annual variations, the background noise was separated into high frequency components of above 1Hz More larger average amplitude is found in winter than other seasons. The average amplitude for 12 seismic stations are compared. It is known that the background noise is considerably larger in stations located in island region such as Jeju, Ulleungdo, and Bagryeongdo seismic stations. However the noise is relatively small in inland stations such as Chuncheon, Chungju and Uljin seismic stations.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.8
• /
• pp.774-781
• /
• 2010

In Korea, the high-speed train is one of the most important mass transportation. Due to its fast speed, the interior noise level is high and it is one of major reason for passenger complaints. In this study, the response of passengers to interior noise was evaluated using sound quality parameters. The effects of various parameters, such as train types, travel speed, rail road, on the calculated sound quality were investigated. The characteristics of interior noise were identified. The obtained results were compared to auditory experimental data. For precise comparison of noises of similar loudness but with different characteristics, paired comparison method was used. From the comparison, important parameters that have influence on the annoyance and loudness of the noise were determined.

• Journal of KSNVE
• /
• v.8 no.4
• /
• pp.603-608
• /
• 1998

In order to obtain basic data for the prediction of railway noise propagation, the noise radiation characteristics (source position, radiation directivity, etc) of trains were measured by using the sound intensity method. The measurements were performed at a side of railway by setting an intensity-probe array. As the measurement results, it was found that rolling noise due to interaction between wheel and rail and motor noise radiation from the lower part of train are dominant. The location of main sound sources can be described as being at the height of 0.1m in the center line of track, and the radiation directivity in the cross section of actually running trains are presented as a dipole source.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.212-216
• /
• 2006

The purpose of this study is to obtain an effective enclosing method for noise reduction of press machine operating in a manufacturing company located in Korea. Noise level of the machine is about $90{\sim}105dB$ which is higher than legal standards by industrial safety and health law. This study has predicted the level of noise reduction according to a step by step prevention plan by considering the characteristics of the cause of noise, the permitted limit of noise levels, problems and economical efficiency attendant upon the noise prevention measures. The predicted level of noise at the plant in accordance with the first step is $71.5{\sim}89.5dB(A)$, and can satisfy the permitted limit of noise in a time period of the day. Based on these results, enclosing method adequate for the selected plant's noise characteristics were suggested.

• Journal of the Korean housing association
• /
• v.9 no.2
• /
• pp.67-78
• /
• 1998

Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and it has become a very serious issue in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult to obtain, because of the lack of basic data and insufficient research works. Especially, in order to establish a successful sound isolation plan for piling work noise, which has high sound pressure level, the characteristics of the impact noise should be closely monitored and analyzed. This study attempts to survey the characteristics of attenuation and propagation of construction equipment noise in piling work by SIP(soilcement injected precast pile) method. In addition, this study intends to get the basic data to establish a standard about construction noise.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2041-2043
• /
• 1999

In order to investigate the radiation characteristics of unmixed line noise from overhead high voltage AC transmission lines, a gap noise generator was manufactured. Disk size which decides capacitance between the noise generator and earth was selected through preliminary indoor experiments and analysis by charge simulation method. The capacitance is one of principal parameters related to inject a proper noise current into lines. The field experiments were performed with the noise generator installed in Kochang 765 kV full scale test line. As the results, the useful data which can be used to analysis the radiation characteristics of noise from transmission lines was obtained. Those are lateral profiles the directivity of antenna toward lines, frequency spectra and so on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.712-717
• /
• 2004

Recently, the concern for the environmental noise has increased due to the growing of the living standard. The environmental noise regulations based on the equivalent noise level are widely used. However, the noise level, which Is based mainly on the magnitude with A-weighting, the important characteristics of noises in frequency and time domains and the impulsive nature cannot be assessed properly. These can have substantial effects on how human respond to noise. Therefore, the noise evaluation methodology based on the sound quality rather than the equivalent noise level can be more suitable to represent human response to the environmental noise. This paper describes the study on environmental noise quality analysis for various noises. A cluster analysis was carried out and the noises were classified into several clusters using the values of sound quality metrics. The classification was confirmed by comparing time and frequency characteristics of the noises. And then the result of Jury testing was analysis.