• Journal of Environmental Health Sciences
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• v.32 no.2 s.89
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• pp.140-148
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• 2006

Recently, indoor air quality (IAQ) in workplace, residential environments and schools has been concerned of people, scientists and related the public, and has recognized the health effects related to indoor air pollution. Therefore, this study was performed to investigate the characteristics of IAQ in 55 kindergartens, elementary school, middle schools, and high schools from June, 2004 to May, 2005 in Korea. We measured indoor air pollutants($PM_{10},\;CO_2$, HCHO, total bacteria colony(TBC), CO, radon, TVOCs, asbestos, and $O_3$), and physical factors(noise, temperature, relative humidity, and illumination) with necessary of management for IAQ in school. We classified into 5 kinds of the school by period since building completion, <1 year, 1-3 years, 3-5 years, and 5-10 years. The concentration of pollutants and the level of physical factors compared with standards and guidelines of IAQ on the Ministry of Environment, the Ministry of Health and Welfare, and the Ministry of Education and Human Resources Development. The major results obtained from this study were as follows. Temperature, relative humidity and illumination among the physical factors did not exceed the standards, but noise exceeded it. Asbestos and $O_3$ did not detect in surveyed classrooms. CO, TBC, TVOCs, and HCHO in kindergartens, TBC in elementary schools, TBC, TVOCs dnd HCHO in middle schools, and HCHO in high schools detected the standards. This study is conducted as a part of efforts to provide a foundational data for further relative researches on management of IAQ of school. Therefore, we suggest that country plan for management of IAQ in school should be established through long-term and continuous investigation for assessment on IAQ in school and health risk assessment for students.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.1
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• pp.16-22
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• 2012

Wireless data communication is easy to be affected by channel noise and degrade reliability and stability by the multipath fading and ISI compared with wired data communication. In this paper, we designed and implemented indoor wireless modem adopted DQPSK modulation scheme for improvement of bandwidth efficiency, and convolutional encoding, Viterbi decoding and hybrid ARQ algorithm combinig FEC with CRC for efficient error control in indoor wireless channel. Testing the implemented wireless modem, we verified the proposed scheme is proper to efficient and reliable indoor wireless data communication.

• Korean Journal of Human Ecology
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• v.9 no.2
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• pp.5-20
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• 2006

This study was a preliminary investigation into improving the environmental and healthy quality of childcare centers. The purpose of this study was to determine the management condition on indoor environment and hygiene of childcare centers in Cheongju. Questionnaire survey was carried out from 11st to 26th of August 2004 by mail. Respondents were consisting of 55 teachers, an executive of each childcare center in Cheongju. From the survey results, there were some problems in 'empty period after remodeling work for preventing sick house syndrome', 'humidity controling', 'glare controling', 'indoor or outdoor noise controling', 'cleaning frequency of each room', 'washing method of toys', 'laundry frequency of rag doll and bedclothes'. So, we need to establish the regulations or give some educations and informations about indoor environment and hygiene to administrators of childcare centers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1139-1146
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• 2010

The indoor noise of the naval vessel is very important related to the optimum environmental conditions for crews as well as the ability of fighting power of antisubmarine. Especially, sonar equipment room is one of the rooms where require to be silent because the informations of the underwater noise are collected and analyzed in there. In this paper, the sound reduction of the TASS console, one of the main noise sources in a sonar equipment room for a typical naval vessel, is described. The noise source of this TASS console is the flowing noise of cooling fan. In order to reduce this kind of noise, the plenum chamber and acoustic elbow were developed. Related to the development of the plenum chamber, the area of the air-outlet and sound absorption of the inner lining were investigated experimentally with the evaluation system of the sound insertion loss. Acoustic elbow was also manufactured and evaluated with the evaluation system of the sound insertion loss. Finally, in order to evaluated the ability of noise reduction of the plenum chamber and acoustic elbow, the indoor noise of the sonar equipment was measured when they were appled to TASS console.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.991-998
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• 2010

In realization of wireless home network system using speech recognition in indoor voice recognition environment, background noise and reverberation are two main causes of digression in voice recognition system. In this study, the home network system resistant to reverberation and background noise using voice section detection method based on spectral entropy in indoor recognition environment is to be realized. Spectral subtraction can reduce the effect of reverberation and remove noise independent from voice signal by eliminating signal distorted by reverberation in spectrum. For effective spectral subtraction, the correct separation of voice section and silent section should be accompanied and for this, improvement of performance needs to be done, applying to voice section detection method based on entropy. In this study, experimental and indoor environment testing is carried out to figure out command recognition rate in indoor recognition environment. The test result shows that command recognition rate improved in static environment and reverberant room condition, using voice section detection method based on spectral entropy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.437-438
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.121-122
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.602-603
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.300-301
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.9-12
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• 2008

There are many place of business in complex building, and recently claims of noise have increased in those buildings. It is most desirable reducing the noise problems to establish the noise criteria considering the noise source and the receiving place of business, which are derived from the dose-response of noise and results of the actual condition. The degree of response to the transmission noise could be changed with background noise level in the receiving stores. In this research, the subjective evaluation for three different background level in receiving place of business or rooms were investigated from subjective tests. The eight business sound source including aerobic music were used for the test.