• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.376-383
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• 2006

Noise induced hearing loss (NIHS), the well-known occupational disease, is caused by continuous excessive noise. The prevention of NIHS is very important, because it is unrecoverable. There are some kinds of hearing protection device (HPD), and those are effective in preventing NIHS. But workers in noisy environment often resist to wearing them. Because they are ready - made products, so workers feel uncomfortable to wear. Also, they didn't maintain the conversation frequency range, so workers are hard to communicate in wearing them. To prevent hearing loss effectively, it is important that workers keep wearing HPD. Therefore, a HPD is needed to be comfortable to wear and be effective not only in hearing protection but also in preserving communication ability. So we proposed a custom - made hearing protection device in which a small acoustic filter is inserted. We designed several kinds of small acoustic filters and carried out some acoustic experiments for measuring characteristics of filters. We confirmed that acoustic transmission characteristic can be adjusted from experimental results using designed small acoustic filters. And we researched for the actual efficiency of a new developed custom - made hearing protection device using a small size acoustic filter. Also, we found out that workers are more satisfied with the new development than a former protection device from a workers' response.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.502-505
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• 1988

This paper is to demonstrate the effectiveness of one point grounding in support of ESS protection. One point grounding provides for the dispatching of excess energy for protection of switching equipment and personnel from lightning discharge hazards and for a natural sink for noise from atmospheric lightning and power transients. In most ESS installations there are a number of different items that must be maintained at a common ground potential for safety, fault protection or noise reduction. The items typically consist of power systems, heating and ventilating systems, distributing frames, repeating equipmets, switching equipments, etc. Grounding system of an ESS Office is most effective when all the ground points are connected to a single, common earth. The one point grounding prvides a common reference potential, keeping all the items of telecommunications facility free from the earth current and voltage hazards.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.62-69
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• 2020

This study intended to evaluate noise level of dental handpieces and the effects of noise cancelling devices. An ear model was designed to measure the level of the noise delivered to the inner ear during dental handpiece operation. The level of noise was measured in various conditions using the ear model and the portable noise meter. Noise level was measured again after applying of 4 different noise cancelling devices to the model ear. The noise level of dental handpieces was 82.5 - 84.4 dB. When 4 types of noise canceling devices were applied, the noise level reduced to 67.4 - 73.8 dB. All 4 devices had statistically significant effect in reducing the noise of the handpiece. Considering the intensity and exposure time, noise in dental clinics can cause hearing damage to dentists. For protection from the risk of occupational hearing damages, noise canceling devices can be recommended.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1146-1151
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• 2011

Acoustic load from rocket propulsion system is main source of random vibration working on the payload. To protect payload from this acoustic load, additional APS(acoustic protection system) is generally applied. Noise reduction capacity of APS can be verified through acoustic test and vibro-acoustic coupled analysis. This paper compared the results of acoustic test and vibro-acoustic coupled analysis about KSLV-I payload fairing with APS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.196-201
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• 2011

Acoustic load from rocket propulsion system is main source of random vibration working on the payload. To protect payload from this acoustic load, additional APS(acoustic protection system) is generally applied. Noise reduction capacity of APS can be verified through acoustic test and vibro-acoustic coupled analysis. This paper compared the results of acoustic test and vibro-acoustic coupled analysis about KSLV-I payload fairing with APS.

• Journal of Digital Contents Society
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• v.5 no.1
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• pp.87-94
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• 2004

In this paper, the digital watermarking algorithm is proposed using CDMA technique for protection of the mobile contents in the mobile environment. The digital watermarking was designed to robust the errors in the mobile environment where pathloss, multipath fading, interference, and noise exist. In case of the multimedia content service in the mobile environment, the construction method of the watermark, the algorithm of insertion and detection are also proposed. The watermark consists of the information of the mobile user. Invisibility and robustness required in watermarking are etimated. It is observed that PSNR of the mobile content inserted the watermark is 90.31 dB, and the signal processing and noise attack are also robust. Especially, because random noise occurs in wireless transmission can overcome, the proposed watermarking algorithm is adequate for protection of the multimedia contents in the mobile environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.617-620
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• 2001

The protection of communication lines against harmful effects from electricity lines is very important with the rapid development of communications network. This paper is introduced the reference of noise voltage and the test methods of foreign countries. Further we will also present study measurement equipment for telecommunications noise voltage and circuit noise phenomenon.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.617-620
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• 2001

The protection of communication lines against harmful effects from electricity lines is very important with the rapid development of communications network. This paper is introduced the reference of noise voltage and the test methods of foreign coutnreis. Further we will also present study measurement equipment for telecommunications noise voltage and circuit noise phenomenon.

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.274-281
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• 2015

Although noise-induced hearing loss (NIHL) is a significant public health problem, many people might not be aware that exposure to loud noise could occur hearing loss. The purpose of this study is to evaluate and analyze how importantly and seriously people are aware of NIHL using a 22-question survey. It was administered to random 150 people including between 20 s to 60 s. The questionnaire contained questions about i) views toward general health issues including hearing loss and tinnitus, ii) noise exposure, and iii) views toward hearing protection. Results showed that hearing loss was defined on a likert scale as 'a very big problem' by 17.33 % of respondents compared with other health issues. Surprisingly, most respondents (82 %) had not heard, read, or seen anything lately related to the issue of hearing loss. Many respondents had experience hearing problem or tinnitus under loud noise situations (85 %), however, only 11.33 % of respondents had used earplugs. Fortunately, many could be motivated to try ear protection if they were advised by a medical professional (80 %) or were aware of the potential for permeant hearing loss (78.67 %). We concluded that awareness of the potential for permanent hearing loss with noise and effective methods of hearing protection should be announced to public for preventing NIHL.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.650-656
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• 2011

The noise inside a naval vessel is very important in considering the need for hearing protection, improving the working environment and maintaining good communications for crews living on board a naval vessel. The indoor noise of a ship usually is specified by the A-weighted sound pressure level, but other evaluating parameters are required to reflect human senses more effectively. This paper uses additional noise indices related to room acoustics, such as NR(noise rating), NC(noise criterion), RC(room criterion), PSIL(preferred speech interference level) and loudness level to evaluate the noise inside cabins on a naval vessel. Using these psychological noise indices, allowable limit of noise level in cabins is suggested through psycho-acoustic evaluation for the noise in cabins.