• Title/Summary/Keyword: Indoor Noise Level

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A Study on the Physical Environment of Middle School Classrooms in Winter -Focusing on the Classrooms in Cheju City- (겨울철 중학교교실의 물리적 학습환경실태에 관한 연구 -제주시를 중심으로-)

  • 오인순
    • Journal of the Korean Home Economics Association
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    • v.35 no.3
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    • pp.193-204
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    • 1997
  • The purpose of this study is to measure some physical environmental factors and to doucument students' perceptions of them. 11 middle schools in Cheju City were divided into four areas according to their locations and two schools were selected for the study. 144 thirteen-year-old students in two middle school in a overcrowded area in Cheju City-one middle school building is insulated and the other is not insulated-were taken for the questionnaire survey. The finding of the study are as follows: 1) The classrooms were not equipped with any heating equipment. The buildings are not insulated well. As a result, the room temperature was much lower(12.9-16.2℃) than comfortable indoor temperature in winter(21.5-24.5℃). The classroom were found to be colder(12.9-16.2℃) than usual pleasant indoor temperature(21.5-24.5℃) in winter. 2) The classroom were so far from the street(20m) that there was little noise from traffic. Nevertheless, the noise level was higher(62.5-66.2 dB(A), when the windows were open; 51.7-62.8dB(A), when closed than the noise tolerance level specified in the Environment Protection Laws(50.0dB(A)). 3) As for the visual environment, the location of classroom, the adequate sun exposure, and the total states of windows in classrooms influenced on the illuminance. While standard indoor illuminance is 300 Lux, the classrooms facing south had illuminance of 231 Lux, from day light: and the ones facing west, 380 Lux. 4) Students generally found other aspects of the physical environment of their classrooms unsatisfactory. Chalk dust was generated to a serious extent near the main chalkboard(0.25mg/㎥) of classrooms.

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Implementation of Indoor Environment Monitoring and Automatic Control System based on Internet of Things (사물인터넷 기반 실내 환경 모니터링 및 자동제어 시스템 구현)

  • Lee, Sang Hoon;Kim, Jin-Yeop;Kim, Su-Yeon
    • Journal of Korea Society of Industrial Information Systems
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    • v.21 no.6
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    • pp.71-80
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    • 2016
  • Along with the increase in the standard of living, the interest and awareness level of the public about environmental issues have also gradually increased. Recently, time spent on indoor activities have increased and the need for awareness and demand on methods in improving the quality of an indoor environment has been recognized. The purpose of this study is to sense the environment information through real-time monitoring of the room environment by using the IoT based technology and to maintain and improve the indoor environment to an appropriate level through the developed interlocking controller device. This provides an automatic control system in improving the indoor environment at home and other small areas like general offices in place of the traditional passive interior environmental improvement actions or large-scale facility control system. A status analysis with the relative reference values of the air quality and CO2, temperature and humidity and illumination and noise was applied through transmitting a control signal to automatic control module in accordance with the nine indoor environment standards set to improve the indoor environment.

Classification of Indoor Air condition Refrigerant noise (에어컨 실내기 냉매 소음의 분류)

  • Jeong, Un-Chang;Kim, Jin-Su;Lee, Sun-Hun;Lee, You-Yub;Oh, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.04a
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    • pp.254-254
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    • 2014
  • 에어컨 실내기는 소비자와 근접해 있는 실내에 설치되며, 필요성에 의해 가동되므로 소비자들의 소음에 대한 반응이 민감하다. 실내기 소음에는 Fan Noise, Cricking Noise, Refringerant Noise 등이 존재한다. 이중 Refringerant Noise 의 경우 Overall Level 은 낮지만 거슬리는 소음이 발행하여 소비자의 가장 큰 불만을 초래한다. Refringerant Noise 에 대해 발생원인 및 해결 방안 측면으로의 연구는 활발히 진행 중이다. 그러나, 소음에 대한 평가 방법에 대한 연구가 이루어지지 않고 있다. 이에 본 연구에서는 에어컨 실내기 Refringerant Noise 을 대상으로 각 소음 별 특성 분석을 수행하였다. 이를 바탕으로 각 소음 별 영향인자를 도출하였다.

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Evaluation of the acoustic environments of open-plan offices in Korean public buildings (국내 공공건축물 개방형 사무실 음환경 평가)

  • Sang Hee Park;Hye-Kyung Shin;Seung-Min Lee;Kyoung Woo Kim
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.1
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    • pp.42-49
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    • 2023
  • Poor indoor acoustic environments negatively affect occupants. Previous research has shown that indoor acoustic environments affect not only task performance and job satisfaction of the occupants, but also their health and well-being. This study aimed for evaluating indoor acoustic environments of open-plan offices located in public buildings in Korea. It also aimed to review the matters that need to be considered in order to improve occupants' acoustic comfort. Indoor noise levels were measured in 13 sites; the measurements were conducted for five consecutive working days from Monday to Friday. The noise levels were evaluated based on the levels recommended by the ISO and the EU ALDREN project. The study found that most of the indoor noise levels measured in the sampled sites during the working hours met the ISO standard. In the case of the levels under unoccupied conditions at night, those at three sites did not meet the recommendation of the ALDREN. In addition, some characteristics of the sites had significant effects on the noise level. Since the exact acoustic performance of the building envelope could not be identified, future research is needed for investigating the relationship between accurate building performance and indoor acoustic environments.

The Assessment of Survey on the Indoor Air Quality at Schools in Korea (국내 일부학교 건축물의 실내공기질 평가)

  • Sohn Jong-Ryeul;Roh Young-Man;Son Bu-Soon
    • 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.

A Study on the Indoor Sound-field Analysis by Adaptive Triangular Beam Method (적응 삼각형 빔 방법에 의한 실내음장 해석)

  • 조대승;성상경;김진형;최재호;박일권
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.3
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    • pp.217-224
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    • 2003
  • In this study, the adaptive triangular beam method(ATBM) considering different sound reflection coefficients and angles of a triangular beam on two or more planes as well as diffraction effect is suggested. The ATBM, subdividing a tracing triangular beam into multiple triangular beams on reflection planes, gives reliable and convergent sound-field analysis results without the dependancy on the number of initial triangular beam segmentation to search sound propagation paths from source to receiver. The validity of the method is verified by the comparison of numerical and experimental results for energy decay curve and steady-state sound pressure level of rooms having direct, reflective and diffractive sound paths.

Investigation of the sound insulation performance of balcony window through field measurement (현장측정을 통한 발코니 창호의 차음성능에 관한 연구)

  • Ju, Mun Ki
    • KIEAE Journal
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    • v.9 no.5
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    • pp.63-68
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    • 2009
  • As with the disappearance of a living room window due to the trend in apartment housing construction that prefers a larger, expanded living room, the sound insulation performance of the balcony window is becoming an important factor to determine the level of indoor noise at an apartment unit. Considering that the indoor noise inside an apartment unit is mandated by law at or below 45dB(A), the balcony window is increasingly assuming an even more important role. Sound insulation performance of the window was measured by examining differences in data involving varying angles of incidence of the sound source as obtained from the same balcony window. Also, acoustic intensity measuring was performed at and around the window to determine its sound insulation quality. Results of measuring on the sound source's angles of incidence indicated that the performance showed some differences in lower frequency ranges, though with no significance. Intensity measuring results showed that the sound insulation performance was reduced near the connection part of the window and the window frame.

A Study on noise measurement result of track noise absorber (도상흡음재의 도상시험에 관한 고찰)

  • Kim, Jin-Ho;Han, Suk-Yoon;Jung, Jang-Yong;Mun, Je-Woo
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.1038-1042
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    • 2008
  • The construction of concrete slab track system is increased recently but the noise level on slab track is 3dB(A) higher than the one on ballast track since most of noise is reflected on slab track. Currently, concrete slab track systems has been designed for Gyungbu high speed line stage 2 and Honam high speed line. For those tracks, noise absorbing blocks are considered. In this paper, noise absorbing blocks were installed at Hwang Hak tunnel for evaluation of noise absorbing blocks and the indoor noise of KTX was measured. The results have done comparative analysis.

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An Experimental Study for Noise Reduction of the Cross-Flow Fan of the Room Air-Conditioners

  • Koo, Hyoung-Mo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.8 no.2
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    • pp.89-100
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    • 2000
  • Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectra of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed, which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared with and without the bounding fence for various flow rates.

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An experimental study for noise reduction of the cross-flow fan of the room air-conditioners (에어컨용 직교류홴의 저소음화를 위한 실험적 연구)

  • 구형모
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.6
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    • pp.871-879
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    • 1999
  • Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectrums of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared of the experimental rig with and without the bounding fence for various flow rates.

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