• Title/Summary/Keyword: Indoor Noise

Search Result 429, Processing Time 0.027 seconds

Evaluation of noise level in the training ship, Saehaerim (실습선 새해림호의 선내 소음도에 대한 평가)

  • HWANG, Bo-Kyu;KIM, Min-Son
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.57 no.1
    • /
    • pp.69-77
    • /
    • 2021
  • The noise environment was evaluated using the ISO recommended NR evaluation curve and PSIL (Preferred Sound Interference Level) in order to investigate the onboard educational environment according to the noise in the Motor Vessel Saehaerim, a fishing training ship under making way. As a result, NRNs were measured at 37-61 dB in accommodation areas, 44-56 dB in work areas, 37-57 dB in educational and conference areas, 83-103 dB in engine areas and 65.3 dB and 51.2 dB in the work and education areas respectively based on PSIL. The NRNs, which evaluated the cabin of the experimental ship according to the purpose, exceeded all of the indoor standard noise recommended by the ISO, and the PSIL had a generally short conversational distance within 0.25-2.3 m and 0.75-1.3 m for teaching and work areas.

Evaluation on Attenuation for Sound-absorbing Measures of Loud Noisy Work-site using Auralizational Technique (가청화를 이용한 고소음 작업장의 흡음대책 평가)

  • Yun, Jae-Hyun;Kim, Jae-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.20 no.8
    • /
    • pp.742-752
    • /
    • 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.

A Study on the Tank Noise Reduction Techniques of Power Transformers (전력용 변압기 외함 소음저감에 관한 연구)

  • Kweon, Dong-Jin;Koo, Kyo-Sun;Kim, Jung-Chan;Kim, Yoo-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.57 no.10
    • /
    • pp.1759-1766
    • /
    • 2008
  • According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint has been increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation from the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated tank noise reduction techniques to develope a low noise transformer. According to the mode analysis of transformer tank, we found out characteristics and locations of noise on the tank, and it's nature vibration was also analysed. On the basis of these analysis, reinforcement equipment was installed around transformer tank, and ellipse shape tank was changed to round shape tank. The effect of noise reduction was evaluated using noise generation source.

Numerical Analysis of Heavy-weight Impact Noise for Apartment Units Considering Acoustic Mode (음향모드를 고려한 공동주택 중량충격음 소음해석)

  • Mun, Dae-Ho;Park, Hong-Gun;Hwang, Jae-Seung;Hong, Geon-Ho;Im, Ju-Hyeuk
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.7
    • /
    • pp.676-684
    • /
    • 2012
  • Numerical analysis was performed to investigate the heavy-weight impact noise of apartment houses. The FEM is practical method for prediction of low-frequency indoor noise. The results of numerical analysis, the shape of the acoustic modes in room-2 are similar to that of acoustic pressure field at the fundamental frequency of acoustic modes. And the acoustic pressure was amplified at the natural frequency of the acoustic modes and structural modes. The numerical analysis result of sound pressure level at 63 Hz and 125 Hz octave-band center frequency are similar to the test results, but at 250 Hz and 500 Hz have some errors. Considering most of bang-machine force spectrum exists below 100 Hz, the noise at 250 Hz and 500 Hz are not important for heavy-weight impact noise. Thus, the FEM numerical analysis method for heavy-weight impact noise can apply to estimate heavy-weight impact noise for various building systems.

Analyzing the Effect of Insole Materials on Vibration and Noise Reduction between Floors (층간소음 방지를 위한 인솔 재질별 진동 및 소음 평가)

  • Seungnam Min;Heeran Lee
    • Journal of the Korean Society of Clothing and Textiles
    • /
    • v.47 no.1
    • /
    • pp.110-122
    • /
    • 2023
  • The COVID-19 pandemic increased people's time at home and caused an 80% increase in noise disputes between floors. The purpose of this study is to propose suitable materials for making indoor shoes (insoles) to minimize noise between floors. Subjects without back pain and leg-related disease (e.g. arthritis, etc.) from three different age groups (childhood, adolescence, and adulthood) were recruited for the study. Five polymer insole materials were considered: Chloroprene Rubber (CR foam), Ethylene Propylene Diene Monomer (EPDM foam), Natural Latex foam, Ethylene Vinyl Acetate (EVA foam), and Polyurethane (PU foam). From these materials, 20 combinations were prepared and randomly tested for noise and vibration. The results revealed a significant difference in noise and vibration levels based on the type of material used and the age of the subject. Nevertheless, all materials under consideration successfully reduced noise and vibration; in particular, type A-C greatly decreased. The CR foam material was especially effective at noise and vibration reduction (p<.01). This study suggests that adding insoles into socks that children wear at home could reduce noise vibration and disputes between floors.

Residents' Responses on Indoor Environmental Efficiency and Spatial Function of Front Balcony in Apartments (아파트 전면발코니의 실내환경 조절효과 및 공간기능 -전면발코니를 실내공간과 통합개조한 경우와의 비교-)

  • 최윤정
    • Journal of the Korean Home Economics Association
    • /
    • v.42 no.5
    • /
    • pp.93-106
    • /
    • 2004
  • The purpose of this study is to make clear the indoor environmental efficiency and spatial function of the front balcony in apartments using responses from residents'. An interview survey carried out during the 14/sup th/∼24/sup th/ of January 2003, and a questionnaire survey was given during the 17/sup th/∼29/sup th/of January. Interviewees consisted of 31 residents living in renovated apartments, which had the front balcony added onto the living room. The respondents of the questionnaire survey consisted of 37 residents living in ordinary apartments with an existing front balcony. The residents living in ordinary apartments show relatively positive responses on the indoor thermal environment during winter, glare by daylight, and outdoor noise. The average heating charges of the renovated apartments came out to be more expensive than the ordinary apartments. In most renovated apartments, the living area converted from front balcony was used as the same functions ('space for drying the laundry', 'storage space', or 'space for cultivating of flower pots') of ordinary front balcony. From the results of this study, it is undesirable to renovate the front balcony as an addition to the livingroom.

Positioning Accuracy on Robot Self-localization by Real-time Indoor Positioning System with SS Ultrasonic Waves

  • Suzuki, Akimasa;Kumakura, Ken;Tomizuka, Daisuke;Hagiwara, Yoshinobu;Kim, Youngbok;Choi, Yongwoon
    • Journal of Power System Engineering
    • /
    • v.17 no.5
    • /
    • pp.100-111
    • /
    • 2013
  • Indoor real-time positioning for multiple targets is required to realize human-robot symbiosis. This study firstly presents positioning accuracy on an autonomous mobile robot controlled by 3-D coordinates that is obtained by a real-time indoor positioning system with spread spectrum (SS) ultrasonic signals communicated by code-division multiple access. Although many positioning systems have been investigated, the positioning system with the SS ultrasonic signals can measure identified multiple 3-D positions in every 70 ms with noise tolerance and error within 100 mm. This system is also robust to occlusion and environmental changes. However, thus far, the positioning errors in an autonomous mobile robot, controlled by these systems using the SS ultrasonic signals, have not been evaluated as an experimental study. Therefore, a positioning experiment for trajectory control is conducted using an autonomous mobile robot and our positioning system. The effectiveness of this positioning method for robot self-localization is shown, from this experiment, because the average control error between the target position and the robot's position at 29 mm is obtained.

A Study on Environmental Standards of School Building (교사환경기준에 관한 연구)

  • Hong, Seok-Pyo;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
    • /
    • v.1 no.1
    • /
    • pp.11-43
    • /
    • 2000
  • The purpose of this study was, through analyzing the previous researches, to grasp the present status of environment of school building(ESB), research the sundry records of each element and, through comparative analysis of the standard of ESB in Korea, the United States, and Japan, select the normative standard of ESB, to clarify the point at issue presented in Regulation of Construction & facility Management for Elementary and and Secondary School in Korea, and to suggest an alternative preliminary standard of ESB. To carry out a research for this purpose, these were required: 1. to investigate the existing present status of ESB, 2. to make a comparative analysis of the standard of ESB in each country, 3. to suggest the normative standard of preliminary standard of ESB, 4. to analyze the controversial points of the standard of ESB in Korea, 5. to suggest an alternative preliminary standard of ESB. The conclusions were as follows: 1. Putting, through analyzing the previous researches, the existing present status of ESB together, it seemed that lighting environment, indoor air environment and noise environment were all in poor conditions. 2. In the result of a comparative analysis of the standard of ESB in Korea, Japan and the United States, in Korea the factors of each lighting and indoor air environment were not presented properly, in Japan, in lighting environment aspect, the standard on natural lighting and the factors on brightness were not presented., and in the USA the essential factors of each environment were throughly presented. In the comparison of the standards on each factor, Korea showed that the standard level presented was less properly prescribed than those of the USA and Japan but it also showed that the standard levels prescribed in the USA and in Japan were mostly similar to the standard levels in records investigated. 3. With the result of the normative standard selection on School Builiding environment factor of prescribed in this study, the controversial points of the standard of ESB in Korea were analyzed and the result was utilized to suggest new preliminary standard of ESB. 4. As the result of the analysis of the controversial points of the standard of ESB in Korea, it was found that the standard of ESB in Korea should be established on a basis of School Health Act and be concretely presented in School Health Regulation and School Health Rule. The factors of each environment was improperly presented in the existing standard of ESB in Korea. Moreover the standard of them was inferior to that of the records investigated and those of in the USA and in Japan and it also showed that the standard of it in Korea was improper to maintain Comfortable Learning Environment. 5. A suggested preliminary standard of ESB acquired through above study as follows: 1) In this study a new kind of preliminary standard of ESB is divided into lighting environment, indoor air environment, noise environment, odor environment and for above classification, reasonable factor and standard should be established and the controling way on each standard and countermeasures against it should be considered. 2) In lighting environment, the factors of natural lighting are divided into daylight rate, brightness, glare. In the standard on each factor, daylight rate should secure 5% of a mean daylight rate and 2% of a minimum daylight rate, brightness ratio of maximum illumination to minimum illumination should be under 10:1, and in glare there should not be an occurrence factor from a reflector outside of the classroom. And the factors of unnatural lighting are illumination, brightness, and glare. In the standard on each factor, illumination should be 750 lux or more, brightness ratio should be under 3 to 1, and glare should not occur. And Optimal reflection rate(%) of Colors and Facilities of Classroom which influences lighting environment should be considered. 3) In indoor air environment factors, thermal factors are divided into (1) room temperature, (2) relative humidity, (3) room air movement, (4) radiation heat, and harmful gases (5) CO, (6) $CO_2$ that are proceeded from using the heating fuel such as oval briquettes, firewood, charcoal being used in most of the classroom, and finally (7) dust. In the standard on each factor, the next are necessary; room temperature: $16^{\circ}C{\sim}26^{\circ}C$(summer : $E.T18.9{\sim}23.8^{\circ}C$, winter: $E.T16.7{\sim}21.7^{\circ}C$), relative humidity: $30{\sim}80%$, room air movement: under 0.5m/sec, radiation heat: under $5^{\circ}C$ gap between dry-bulb temperature and wet-bulb temperature, below 1000 ppm of ca and below 10ppm of $CO_2$, dust: below 0.10 $mg/m^3$ of Volume of dust in indoor air, and ventilation standard($CO_2$) for purification of indoor air : once/6 min.(about 7 times/40 min.) in an airtight classroom. 4) In the standard on noise environment, noise level should be under 40 dB(A) and the noise measuring way and the countermeasures against it should be considered. 5) In the standard on odor environment, odor level under Physical Method should be under 2 degrees, and the inspecting way and the countermeasures against it should be considered.

  • PDF

Noise Measurement Method Development and Correlation Analysis According to Measurement Location of Small Unmanned Robot (소형 무인 로봇의 소음 측정법 개발 및 측정 장소에 따른 상관성 분석)

  • Ok, Jinkyu;Park, Eunjoo;Park, Minsu;Lee, Myungchun
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.20 no.5
    • /
    • pp.633-638
    • /
    • 2017
  • The small unmanned robot developed in this paper can perform tasks such as surveillance and reconnaissance in the battle field. The noise generated during the operation of the robot may expose the operation area. Therefore, in this study, we developed a method to quantitatively measure the noise of the developed small unmanned ground robot. The criteria for noise measurement in indoor and outdoor are presented. It was used for statistical verification method to verify the reliability of the developed noise measurement method. The noise was measured at different places, and the correlation was analyzed. Thus, we proposed a method to predict the noise level in the operation area where the robot is operated by the noise test data measured during the development process.

An Experiment Study on the Structure-borne Noise Reduction of Building Nearby the Road by Using Ballast Mat Pavement Method (도상 매트 공법 도로포장에 의한 자동차 도로 인근 건축물의 고체전파음 저감효과에 관한 실험적 연구)

  • 이익주;유제남
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.14 no.11
    • /
    • pp.1153-1160
    • /
    • 2004
  • In contemporary society, vibration and noise in the road nearby buildings have become social problems as vehicles operation has increased. Especially. in the case of the building used to art performance, available suitability of the building is tested by the indoor noise class. Therefore, the Purpose of this paper is the measurement of the structure-borne noise of Seoul Art Center nearby Umyeonsan tunnel and analyzing the effects of countermeasure to it. To measure the effects of countermeasure, not only structure-borne noise is measured, but also the vibration is measured, before and after the construction of Pavement using pad and porous asphalt. Consequently, the sound pressure level in art center 1st floor is reduced after mat pavement method, structure-borne noise that was high In 25Hz wide-band before pavement decreased regardless of experimental vehicle's velocity Using porous asphalt pavement the noise was reduced about 3 dB(A).