• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1012-1013
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• 2006

Marine technology must advance to meet the needs of a wealthier and more demanding public while at the same time provide greater environmental protection. Pollution noise and vibration is the specific issue being discussed in this paper Noise is of course due to vibration from high speed engines driving generators, entilators, winch and other gear, while underwater noise pollution results from the propellers and the resistance produced by the hull of the ship moving through the water. Vibration is also a factor in potential damage to sensitive electronic gear and metal fatigue. The issue of noise pollution does not cease when a vessel enters her berth and the main engines shut down. There is still the matter of ventilation and other mechanical factors at work to maintain a comfortable, efficient environment. We measured the noise level and vibration displacement in the training ship A-Ra at underway and Berth. The authors analyzed the frequency of noise and maximum vibration displacement in the position.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.63-68
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• 2015

PURPOSES : A study on the efforts to minimize the road traffic noise has been underway. An attempt has been made to measure the noise level using a noise map; however, the attempt is limited to certain areas only. In general, a noise barrier is employed to prevent road traffic noise; however, unplanned noise barriers developed without considering the surrounding environment, including excessively high walls, cause problems such as infringement on prospect right. Noise ceiling at daytime in Korea is 68 dB(A), which is relatively higher than in other countries. METHODS: The noise barrier used mainly for road noise reduction was analyzed to estimate the optimal height. Related variables such as road width, the height of the upper part, distance to the building, and angle (for instance, $30^{\circ}$). RESULTS : A formula to calculate the optical height of the noise barrier, considering the road environment (i.e., parameters such as road width and distance to building), was developed in this study in an attempt to mitigate the noise generated from the road. CONCLUSIONS : The formula to calculate the noise barrier is expected to lead to cost saving, accurate installation of barriers, and protection of the right of prospect.

• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.24-34
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• 2016

The popularity of personal listening devices(PLDs) has increased over past years, especially, in adolescents. Overuses and missuses of PLDs could be the cause of noise-induced hearing loss (NIHL). The purposes of this study were (1) to survey middle school students' habits using PLDs, knowledge of hearing loss and attitude of hearing protection and (2) to develope a questionnaire for assessment of habits using PLDs, knowledge of hearing loss and attitude of hearing protection in adolescents. The 41-item questionnaire was designed and used to survey middle school students' habits using PLDs, knowledge of hearing loss and attitude of hearing protection. A total of 404 middle school students aged 14-15 years participated in the survey. Most of the students were found to use PLDs soundly. However, 30 % of students used PLDs for more than 3 hours a day. Also, almost all of the students did not understand knowledge of the causes of hearing loss, but showed interests in hearing protection. However, some students had insufficient understanding of the causes of hearing loss and the needs of hearing protection. The results suggest that the development of programs for adolescents' hearing health is needed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.841-849
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• 2013

Workers engaged in construction works have been exposed to high levels of noise during their work in tunnels. Noise is one of the major health hazards for employees working in construction sites. The aim of this study is to evaluate the noise levels generating from tunneling equipments such as jumbo drills, backhoes, payloaders, shotcrete machines and service cars. Explosion and turbo fan noises were also monitored. A high precision sound level meter was introduced for measuring LAeq, LAFmax, LAFmin and LCpeak noises in 5 tunneling work sites that were located in Seoul, Kyunggi-do and Kangwon-do areas with NATM and shield methods. The highest noise was recorded by explosion(151.9 dB LCpeak) followed by jumbo drills of higher than 110 dB(A) LAeq. Backhoe normally generated 90~110 dB(A) LAeq while breaking work of rock showed additional around 5~15 dB(A). Noise exposure levels for payloader and shotcrete machine scored more than 90 dB(A) which might be a source of noise-induced hearing loss. Additional research in revealing noise levels from construction equipments operating in tunneling works may enhance the protection of workers who exposed to noise primarily at the sites.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.95-102
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• 2019

The purpose of this study is to investigate the correlation between aluminum form work and noise-induced deafness by conducting special health examination on construction aluminum worker and noise measurement at the workplace. All the 11 aluminum form workers were diagnosed with noise-induced deafness after holding a special health examination. The workers have not had any previous history of noise-induced deafness which indicates that aluminum form work is related to noise-induced deafness disease. The impact noise of 120 dB(A)~125 dB(A), which exceeds the regulations of industrial safety and health act, was found during the dismantling rather than installation when noise measurement was made at the aluminum workplace. The aluminum form workers could permanently lose the hearing sense if they are exposed to this impact noise. This study is to suggest the method to prevent noise-induced deafness for aluminum form workers by firstly giving out hearing protection equipment at the construction site and secondly installing rubber mat, soundproof panel as well as changing the noise-lowering technique.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.163-168
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• 2007

A light railway operationis an effective means to solve a traffic problem of the city however, noise and vibration is pollution happened. This paper studied noise and vibration pollution of a light railway operation in order to let a decrease. The study range was only track condition and civil engineering structure condition. The way how we decrease noise and vibration in a protection vibration track, ballasted track, non-ballasted track, floating track trends was devoted is long rail laying, low vibration track lying. It was the most economic that the examination results track section a complement, and it was proved that a certain way.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.891-897
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• 2013

The power system frequency plays an important role in monitoring and controlling the power system. The frequency can be measured through discrete Fourier transform (DFT) coefficients of its positive fundamental frequency. The accuracy of the frequency estimate is severely affected by noise in the power system signal and the leakage effect of the negative fundamental frequency in DFT. This paper proposes a DFT-based frequency estimation algorithm to cope with the noise as well as the leakage effect. In this algorithm, two suitable digital filters are introduced to reduce efficiently frequency estimate error due to the noise. These filters are designed to use a digital bandpass filter and a second-degree integrator. The effectiveness of the proposed algorithm in reduction of frequency estimate error is verified through simulations on noise, harmonics and frequency deviation.

• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.742-752
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• 2010

In case of the working machine that using in the loud-noisy workplace, as it generates the loud-noise, it is influencing a physical, mental bad effect to those workers. Accordingly, though the noise countermeasure for the loud-noisy workplace is acutely requiring, until now, those methods that wearing the soundproof-protection tool, or restriction the working hours, and minimize the noise exposure volume, were mainly used. However, such noise countermeasures occur many problem points. On such point of view, using the acoustic simulation technique, let the workers to choose the workplace where suffering many damages due to the noise of working machine, and after grasp the physical property of working machine and indoor acoustic characteristic, this Study has attempted to grasp the reduction degree of noise level at before-improvement?after-improvement, through the sound-absorption measure. Passing through such preceding step, using auralizational technique based on the noise of working machine of before-improvement after-improvement, and by conduct psycho-acoustics evaluation, this study intended to investigate the change degree of subject reaction. As the result of evaluation, it is considering that the noise-reduction countermeasure method for the loud-noisy workplace could be much effective, through the sound-absorption measure.

• Journal of the Ergonomics Society of Korea
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• v.15 no.1
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• pp.79-90
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• 1996

A research project was conducted to assess the levels of noise exposed to "Noraebang" users and potential hazards to noise-induced hearing loss due to commercial Noraebang noise. A two-way, mixed-factors factorial design was employed for the experiment using independent variables of "noise source" (no- singer, 1-singer, and 2-singer conditions) and "music type" (Trot, Ballad, and Rock music) with 18 normal hearing subjects. Each singer group sang 5 popular songs of each music type in each signing condition, whereas background music was just played for the no-singer condition. For each music played/sung, equivalent continuous sound pressure levels and maximum sound pressure levels were measured for data analysis purposes. Pure-tone audiometry was applied for measuring subjects' hearing threshold levels before and after exposure to Noraebgang noise. The statistical analyses indicate that average continuous noise levels due to Noraebang leisure environment were very serious, especially when two people were singing (higher than 95 dBA). Furthermore, maximum noise levels often exceeded the OSHA's non-premissible 115 dBA level. Worse yet, hearing loss assessment implies that Noraebang facilities may pose a serious threat to noise-induced hearing loss, based on 6-8 dB loss at 125 Hz and 8 dB loss at 4000 Hz after about 1-hour Noraebang noise exposure.