• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.742-746
• /
• 2008

With the trend of factory automation, nowadays, much industrial machinery tends to be put into 24-hours operation a day. However, these trends in industrial equipments also increase the possibility of various mechanical problems and bring about innumerable maintenance cost. There is a strong need of the condition monitoring and diagnosis for industrial equipment, especially rotating machinery, since they are connected not only to the reduction in the maintenance costs but also connected to the enhancement of production efficiency. Generally, to evaluate the operating conditions in the machinery in the industrial field, various physical properties are monitored. Among them, vibration and Noise signals are the mist important indicator and it is effectively used in many diagnosis systems for machinery. Much previous research is based in the FFT (Fast Fourier Transform) method. The spectral analysis is assumed that the signal is stationary. However, almost random signals are non-stationary. The wavelet transform has been recognized an efficient Method. Most interesting sounds have time-varying features. Signal processing techniques for the analysis of transient sound have been not clearly given yet.

• Journal of the Korean Society of Safety
• /
• v.21 no.5 s.77
• /
• pp.12-16
• /
• 2006

This paper deals with the noise evaluation and noise reduction of a reciprocating air-compressor. The reciprocating air-compressor is widely used in the small and medium sized industrial firms, many employees exposed and irritated by their noise in the workplace. Thus, appropriate noise control actions should be taken to prevent hearing loss due to the its noise exposure. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known to be motor, belts, suction valves, discharge valves, moving parts, and flow-induced noise caused by edges or discontinuities along the flow path including expansions, contractions, junctions and bends. As a result, the main noise sources of the air-compressor are categorized by the suction and discharge noise, valve noise, and compressed air tank noise. Based on the investigations, mufflers are designed to reduce both the suction and discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, polyethylene resin is used the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings. As a result of the countermeasure plans, a noise reduction up to 10dB(A) could be achieved for the air-compressor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.1120-1125
• /
• 2002

Recently Korean Industrial Standards has been revised and established newly accordance with the ISO system, especially ISO 140 series. This study aims to introduce and review ISO l1654 which contents rating of sound absorption. It is available to establish appropriate evaluating method and Korean Industrial Standard of the sound absorber for use in building.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1998.06a
• /
• pp.745-749
• /
• 1998

Mathematical morphology (MM) has been introduced as a powerful tool for studying the geometrical properties of images, MM is a good approach to digital image processing , which is based on the shape feature. The MM operators such as dilation, erosion, closing and opening have been applied successfully to image noise reduction. The MM filters can easily filter the noise when the noise factors are known. However it is very difficult to reduce the noise when images are ambiguous, because the boundary between the noise and object is vague. In this paper, we propose a new method to reduce noise from ambiguous images by using Fuzzy Mathematical Morphology (FMM) operators. Performance evaluation via simulations show that the FMM filters efficiently reduce the image noise. Furthermore, the FMM filters show a good performance compared with the conventional filters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.205-209
• /
• 2007

During after the Industrial Revolution until now, as many of working machinery and tool had been invented, human could save man power and time. However, because such instruments generate a loud noise according to their use-purposes and dimensions, they are affecting a physical, mental bad influences to those workers. Therefore, while a reduction measure against the instrument-noise that generates at workshop is sincerely necessitated, due to lack of the research and data concerned with that, a lot of difficulties are on suffering. Standing on such point of view, this Study has measured analyzed the characteristics of diverse instrument-noises generate at workplace, and would intends to present a fundamental material for establishment more comfortable working environment by prediction on the noise in loud noise workshop, based on the above.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.695-698
• /
• 1999

Passive noise reduction is a classical approach to attenuate industrial noise. But Active noise cancellation has several advantages over the passive noise cancellation. Such a system offers a better low frequency performance with a smaller and lighter system. This paper presents an active closed loop control system which consists of an controller for inverting and compensating the phase delay, an microphone for picking up the external noise, and loudspeaker for radiating the acoustic anti-phase signal to reduce external noise. The noise in the phase delay covered from 80$^{\circ}$ to 270$^{\circ}$ tends to be reduced. The degree of noise cancellation obtainable with this system reaches value about 17㏈.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1344-1349
• /
• 2000

With rapidly industrial development, a railway has become of a main traffic means. But, the railway noise has caused much annoyance for the residents living nearby railway tracks. Therefore, in our country, for established of Quite dwelling environment, execute regulation standard of railway noise from January 1, 2000. Efficiency soundproofing measures, however, are very difficult because of the lack of basic data and insufficiency of the existing research. In this point, this study attempts to survey the characteristics of attenuation and propagation of railway noise in by existence of noise barrier. And this study intends to get the basic data for establishment of a standard about railway noise.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.1
• /
• pp.194-202
• /
• 2017

In this study, we measured and analyzed electrical noise signals present in devices and systems operated in industrial facilities. Based on the analytic findings, we studied the most effective improvement measures for eliminating such noise signals. Leakage current and ground current generate data interferences in communication systems, and therefore we measured leakage current and ground current. We also measured and analyzed electrical noises in power systems to predict noise pathways and interference routes. Furthermore, we proposed the most effective and reliable improvement measures for blocking off various noise signals and safely eliminating them by improving the internal wiring of the facilities and grounding systems. As a final step, we conducted the proposed improvement measures and confirmed that they helped to improve the operations of the device sand systems in service by re-measuring electrical noise signals and comparing them with those measured before the proposed improvement measures were implemented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.707-710
• /
• 2001

With rapid industrial development, railway has become a main traffic means. But, the railway noise has caused much annoyance for the residents living nearby railway track. Therefore, it is necessary to establish the environmental quality standards for railway noise like the environmental quality standards for traffic noise. In this study, the domestic and foreign standards for railway noise were investigated with analysis of existing data and field survey of noise condition at near a railway.

• Journal of Environmental Science International
• /
• v.16 no.7
• /
• pp.823-830
• /
• 2007

Traffic noise is a kind of noise caused by cars, trains and aircraft. Among them, noise produced by cars is the most important factor in cities. According to the National Institute of Environmental Research(NIER)'s survey, Road traffic noise levels in Susan are the highest of all the cities in Korea. So, appropriate measures for road traffic noise reduction is required. For this purpose, the construction of a noise map in Susan will playa vital role. However, road traffic noise formulas are constructed considering regional characteristics such as each country road's environment and vehicle quality. Therefore, prior to constructing a noise map in Susan, examination processes about each formula constituent status and estimation process are required preferentially. In this research, the basic first stage is to estimate Susan's road traffic noise. First, investigate characteristics of each road traffic noise estimate and using this, a noise map is constructed for road traffic noise in Susan. Then the adaptation of a road traffic noise formula is evaluated.