• Safety and Health at Work
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• 제8권4호
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• pp.364-370
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• 2017

Background: Labeled noise reduction (NR) data presented by manufacturers are considered one of the main challenging issues for occupational experts in employing hearing protection devices (HPDs). This study aimed to determine the actual NR data of typical HPDs using the objective fit testing method with a microphone in real ear (MIRE) method. Methods: Five available commercially earmuff protectors were investigated in 30 workers exposed to reference noise source according to the standard method, ISO 11904-1. Personal attenuation rating (PAR) of the earmuffs was measured based on the MIRE method using a noise dosimeter (SVANTEK, model SV102). Results: The results showed that means of PAR of the earmuffs are from 49% to 86% of the nominal NR rating. The PAR values of earmuffs when a typical eyewear was worn differed statistically (p < 0.05). It is revealed that a typical safety eyewear can reduce the mean of the PAR value by approximately 2.5 dB. The results also showed that measurements based on the MIRE method resulted in low variability. The variability in NR values between individuals, within individuals, and within earmuffs was not the statistically significant (p > 0.05). Conclusion: This study could provide local individual fit data. Ergonomic aspects of the earmuffs and different levels of users experience and awareness can be considered the main factors affecting individual fitting compared with the laboratory condition for acquiring the labeled NR data. Based on the obtained fit testing results, the field application of MIRE can be employed for complementary studies in real workstations while workers perform their regular work duties.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1627-1633
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• 2017

This paper proposes a voice enhancing ear-protection system which is based on feedback active noise control(FBANC). The proposed system selectively suppresses the background noise and preserves the talking voice by controlling the adaptive algorithm with the voice activity period detection module. The noise reduction performance of the proposed noise canceling algorithm is analytically derived for the two key performance affecting parameters, i.e., electro-acoustic coupling distance and noise bandwidth. The proposed system is also implemented with a floating-point DSP system and its performance is experimentally tested to compare with the analytically derived results. The achieved levels of noise reduction for the three different noise bandwidths cases, i.e., 10Hz, 50Hz, and 90Hz, are high to show 17.05dB, 10.54dB and 8.99dB, respectively. The feasibility of the proposed system is also shown by the peak noise reduction achieved more than 25dB while preserving the voice component in the frequency range between 200-800Hz.

• 한국의류학회지
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• 제33권5호
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• pp.679-690
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• 2009

The purpose of this study was to compare clothes-wearing in winter between Korean and Japanese college students and to provide the fundamental data for apparel manufacturers to produce young woman's clothing. A total of 332 Korean female students in the capital area and 347 Japanese female students in Tokyo aged between 19 and 25 were used into data analysis from December 2007 to January 2008. Their majors were Fashion Design and Clothing & Textiles. The questionnaires consisted of 36 questions in total. Their details were as follows: 2 questions about the purposes of wearing clothes in winter, 5 questions about whether or not underwear was worn and its types, 9 questions about the types of wearing outer garments, 17 questions about the types of wearing accessories, and 3 questions about demographic characteristics. The results were as follows: It was found that many female students wore clothes for "a protection purpose" or "an ornamental purpose" in winter. There was significant difference between Korea and Japan. As for the question about whether or not underwear was worn in winter, less Korean students answered than Japanese students that they wore both of upper and lower underwear. More upper underwear was worn than lower underwear. As for the question about the types of wearing outer garments, both Korean and Japanese students answered that they wore 3-layered upper garments in winter most. The types of upper garments worn in winter were different between Korea and Japan. The lower garments worn in winter were different between the two countries as well. The Korean students mainly wore pants while the Japanese students wore skirts. As for the types of accessories, there was significant difference between Korea and Japan about most of the questions about hats and gloves. Korean students wore them more than Japanese students. There was no significant difference between the two countries about whether or not scarves or earmuffs were worn. In both countries, more students wore scarves while less students wore earmuffs.

• 한국의상디자인학회지
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• 제13권3호
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• pp.135-147
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• 2011

The purpose of this study was to analyze clothes-wearing of Chinese female university students in Hangzhou. By random sampling, a total of 183 Chinese female students in Hangzhou aged between 17 and 24 were used into data analysis from November 20, 2010 to January 20, 2011. The questionnaires consisted of 36 questions in total. The results were as follows : According to the result of the purpose of wearing clothes in winter, it was found that many female students wore clothes for a "protection purpose" or "ornamental purpose" in winter. As for the question about whether or not underwear was worn in winter, Chinese students answered that more upper underwear was worn than lower underwear. As for the question about the types of outer garments, Chinese students answered that they wore 3-layered upper garments in winter most. The upper garments worn in winter preferred most was long coat(68.3%). In the survey on the types of accessories, More Chinese students wore mufflers and gloves while less students wore hats and earmuffs.

• Investigative Magnetic Resonance Imaging
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• 제9권2호
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• pp.134-139
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• 2005

목적 : 청각의 뇌기능 영상 검사 시 소음 감쇠기의 유용성을 알아보고자 하였다. 대상 및 방법 : 소음 감쇠기는 실리콘 이어폰, 귀마개 그리고 마스크로 구성하였다. 마스크와 귀마개는 방음효과가 크다고 알려져 있는 부드러운 재질의 폴리우레탄 시트와 폴리우레탄 폼을 사용하여 제작하였다. 500 Hz의 순음 자극에 대한 청각의 뇌기능 자기공명영상 실험은 4명의 지원자를 대상으로 다음의 세가지 경우로 구별하여 시행하였다: 첫째, 마스크와 귀마개, 이어폰을 모두 착용한 경우, 둘째, 귀마개와 이어폰만을 착용한 경우 그리고 마지막으로 소음 감쇠기를 착용하지 않은 경우 이다. 데이터 획득을 위하여 고성능 경사자계 시스템이 갖추어진 1.5 T 자기공명영상장치에서 BOLD 자기공명 영상기법을 사용하였다. 영상 데이터는 SPM 99 분석프로그램을 이용하여 분석하여 활성화 지도를 획득하였다. 결과 : 소음감쇠기의 모든 구성요소를 사용한 경우 활성화는 주로 일차 청각중추에서만 집중되어 나타나는 결과를 얻었다. 귀마개와 이어폰만을 착용했을 때는 청각의 뇌 활성화 영역이 일차 청각중추와 이차 청각 영역에 분산되어 나타는 결과를 얻었으며 마지막으로 소음감쇠기를 사용하지 않은 경우 청각영역이 오른쪽의 일부만이 활성화 되었다. 결론 : 마스크, 귀마개, 이어폰으로 구성된 소음 감쇠기는 청각의 뇌기능 영상 검사 시 매우 유용할 것으로 기대된다.