• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.211-215
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• 2011

Generally, sound power is one of the most significant factors to predict and assess noise from sound sources. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we propose a method to estimate sound power generated due to wheel/rail interaction and propulsive equipment from the measurement of noise emitted from rolling stocks and verify the estimation method by comparing with the other sound power estimation formula. We also analyze the sound power of rolling stocks which are operating in domestic lines such as EMU, Mukoonghwa, KTX using the method proposed in this paper.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1223-1228
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• 2010

The conventional noise control attempts to simply reduce the level of product noise. But it is very straight forward way that we have considered human perception on noise. Since human listening is very sensitive to sound. Evaluation of the sound quality of a vacuum cleaner is studied base on human sensibility engineering. In this paper, we choose six vacuum cleaners that are sold in Korea and reduced noise control. The sound quality of vacuum cleaner noise is analyzed by employing the subjective evaluation and by representing them in terms of the objective quantities. Semantic differential method is used to study sound quality Evaluation. To analyze the sound quality of vacuum cleaner noise, consider the coefficients of correlation between sound metrics and subjective rating. The linear regression models were obtained for the subjective evaluation and sound quality metrics.

• Journal of the Korea Computer Industry Society
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• v.4 no.10
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• pp.599-610
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• 2003

Sound equipment has developed rapidly as digital technology has quickly matured. Due to this fact, the necessary knowledge and skills are new. Moreover, improvements in digital surrealism in acoustical modeling have increased the challenges facing future audio engineers. Therefore, the necessity of Instruction in the use of sound equipment is needed for the specialist and amateur, alike. However, it is not easy to loam all kinds of sound equipment and systems which are upgraded often. It is necessary to offer a virtual environment that accurately simulates the manipulation and experiences of new sound recording technologies. The purpose of this study was to design a web based virtual operating system for sound equipment technologies which guide user to learn basic principles of usage and production techniques. The virtual simulation system was designed to aggressively implement an actual equipments so that user manipulation will accurately reflect current equipment usage and behavior.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.580-586
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• 2005

In this study, experimental tests for driving noise of various optical disk drives (ODD) have been performed using 1/2' microphone noise measurement system. Several new and old ODD models by different manufacturers are practically considered and compared far realistic driving conditions. Sound insulation case with absorbing material fur the present experimental tests is designed and constructed using CATIA system. It is found that average data transfer rate, operating RPM, and sound noise level seems to be different for the same opposed speed ODD by different manufacturers. Moreover, driving sound noise level can be largely affected by both tray shape and driving speed even for the same apparent data transfer rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.217-220
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• 2001

We have developed the gear sound recognition system of mechanical timer. A mechancal timer is superior in endurance to electronic timer. So it is reliable under severe operating environment. It is putting together several kind of gears. Therefore when the timer operates, it emits mechanical sound of gears. We have chosen a microphone to detect the gear sound. A microphone is more efficient and convenient than other sensors. Because it is of low price and non-contact type sensor. For ease of measurement we designed real-time processing software based on graphical user interface.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1169-1176
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• 2005

In this study, experimental tests for driving noise of various optical disk drives (ODD) have been performed using 1/2' microphone noise measurement system. Several new and old ODD models by different manufacturers are practically considered and compared for realistic driving conditions. Sound insulation case with absorbing material for the present experimental tests is designed and constructed using CATIA system. It is found that average data transfer rate, operating RPM, and sound noise level seem to be different for the ODD models with same denoted speed by different manufacturers. Moreover, driving sound noise level can be largely affected by both tray shape and driving speed even for the condition of the same apparent data transfer rate.

• Safety and Health at Work
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• v.8 no.2
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• pp.226-230
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• 2017

The performance of sound barriers was evaluated to determine their technical effectiveness and practicality in reducing noise exposures to operating engineers in construction. Commercially purchased sound dampening mats (SDMats) were installed inside three heavy-equipment engine compartments. Sound pressure levels (SPLs) were measured before and after installing the SDMats while the equipment was on idle and full-throttle settings where it normally operates. SPLs inside the heavy-equipment operator cabs were significantly reduced by 5.6-7.6 dBA on the full-throttle setting following installation of the SDMats (p < 0.01). The evaluated engineering control intervention was simple to install, affordable, and substantially reduced the engine noise reaching the heavy-equipment operator, potentially reducing reliance on hearing-protection devices to protect construction workers from noise exposures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.1000-1004
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• 2008

As performance of medical air compressor improve, the problem of noise increased. Noise is very important to medical air compressor because most of this installed inside of building. The main goal of this paper is show TPA (Transfer Path Analysis) result for contribution analysis using PAK system. Generally, the conventional TPA method consists of two steps. First, transfer functions between output sound and sources are measured by excitation experiment. Second, transferred sound in each transfer path is generated by multiplying the transfer function and the sound source signal. Then, if the output sound synthesized from all transferred sounds doesn't give good agreement with the measured output sound (i.e., the accuracies of the transfer functions are low), setting a suitable countermeasure guideline becomes difficult. For obtaining highly accurate transfer functions, eliminating correlations among transfer functions and noise included in the measured data are necessary. In the new method with PAK system, the vibration acceleration and sound signals around the sound sources and the output sound were measured simultaneously to obtain the transfer functions when compressor was operating. By applying PAK system, a highly accurate and efficient transfer path analysis method was developed that does not require an excitation experiment.

• Journal of KSNVE
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• v.5 no.2
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• pp.169-181
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• 1995

A theoretical model has been studied to describe the sound radiation analysis for structural vibration noise control of tire under the action of random moving line forces. When a tire is analyzed, it has been modeled as a curved beam with distributed springs and dash-pots which represent the radial, tangential stiffness and damping of tire, respectively. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y = 0 and to be axially infinite. The material of curved beam and elastic foundation are assumed to be lossless, and governed by the law of Bernoulli-Euler beam theory. The expression for sound power is integrated numerically and its results examined as a function of Mach number(M), wavenumber ratio(.gamma.) and stiffness factor(.PSI.). The experimental investigation for structural vibration noise of tire under the action of random moving line forces has been made. Based on the STSF(Spatial Transformation of Sound Field) techniques, the sound power and sound radiation are measured. The experimental results show that operating condition, material properties and design factors of the tire have a great effect on the sound power and sound radiation characteristics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.264-274
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• 2012

Evaluation on the environmental noise is carried out by surveying subjective response of residents with physical measurement of noise during long period in field. Particularly field survey is used to make regulations from the analysis on how many people are annoyed for specific noise level, and laboratory test used to analyze the relationship between physical parameters of noise and subjective responses. In the laboratory controlling the variables is easy but the results could be biased because the condition in room would be different with field. Most of all noise exposure time is considered to be different with real situation, and this study aimed to evaluate the subjective response by exposure time of transportation noise, by applying three kinds of variable how much they give effects on the annoyance as the exposure time is operating condition, windows type and sound level. As a result there was somewhat difference between operating type and annoyance, which is caused by the sound characteristics operated in different condition. However the window type didn't give much effect to the annoyance as much as sound type. This means that the subjective response could give similar result by exposure time even for different window types. Most of all, the main factor affecting subjective response is considered to be the sound level and the exposure time.