• Asian Journal of Atmospheric Environment
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• v.7 no.2
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• pp.72-84
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• 2013

In the study, pollution levels of indoor polycyclic aromatic hydrocarbons (PAHs) in public facilities (vapor phase or particulate phase) were evaluated, and a health risk assessment (HRA) was carried out based on exposure scenarios. Public facilities in Korea covered by the law, including underground subway stations, funeral halls, child care facilities, internet cafes (PC-rooms), and exhibition facilities (6 locations for each type of facility, for a total of 48 locations), were investigated for indoor assessment. For the HRA, individual excess cancer risk (ECR) was estimated by applying main toxic equivalency factor (TEF) values suggested in previous studies. Among the eight public facilities, internet cafes showed the highest average $PM_{2.5}$ concentration at $110.0{\mu}g/m^3$ (range: $83.5-138.5{\mu}g/m^3$). When assuming a risk of facility exposure time based upon the results of the surveys for each public facility, the excess cancer risk using the benzo(a)pyrene indicator assessment method was estimated to be $10^{-7}-10^{-6}$ levels for each facility. Based on the risk associated with various TEF values, the excess cancer risk based upon the seven types cancer EPA (1993) and Malcolm & Dobson's (1994) assessment method was estimated to be $10^{-7}-10^{-5}$ for each facility. The excess cancer risk estimated from the TEF EPA (2010) assessment was the highest: $10^{-7}-10^{-4}$ for each facility. This is due to the 10-fold difference between the TEF of dibenzo(a,e)fluoranthene in 2010 and in 1994. The internet cafes where smoking was the clear pollutant showed the highest risk level of $10^{-4}$, which exceeded the World Health Organization's recommended risk of $1{\times}10^{-6}$. All facilities, with the exception of internet cafes, showed a $10^{-6}$ risk level. However, when the TEFs values of the US EPA (2010) were applied, the risk of most facilities in this study exceeded $1{\times}10^{-6}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.586-591
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• 2010

The sound field can be classified to the direct and reverberant sound field. If the sound absorption material in a room is not applied sufficiently, the reverberant sound field increases and the sound pressure in a room also increases when the sound source exists in a room. Therefore, the reverberation time should be controled in order to reduce the reverberant sound as well as sound pressure level in a room. Even though the reverberation time is specified and researched widely in architectural engineering, it is rarely performed in a marine engineering. Therefore, in this research, the reverberation time in a navel vessel is researched related to the noise reduction in a cabin.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.78-82
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• 2004

The cross-flow fan which is used for air-conditioner indoor units were studied experimentally. The recent trend shows that the room air-conditioners need to be good-looking. According to the visual design concepts the intake regions of the fan can vary, which leads to the loss of the performance and the increase of the noise of the fan. In order to optimize the performance of the fan and minimize the aerodynamic noise for the system, the performance characteristics and the noise of the cross-flow fan have been investigated at the various conditions of the intake region of the unit.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.12
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• pp.1123-1128
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• 2009

Noise radiated from medical treatment at dental clinic will affect the patients. On such point of view, We investigated the noise characteristics in case of medical treatment (scaling, tooth eliminating) and non-medical examination (idling) and also evaluated the degree of indoor noise using the evaluation index such as PSIL, NRN and made up a questionnaire about the reactions to noise. As a result of noise evaluation, it shows that the range of noise level is 67.7~78.3 dB(A) and frequency is very high (above 4 k Hz) and respondents are affected by noise (unpleasantness, hesitation to visit dental clinic, shivering with noise, being astonishment). Analysis by PSIL showed that it was no problem to conversation between worker and patient. But it exceeded the noise permit level in working space by NR-curve. To relieve a fear of noise in patients, they are considered to offer the ear protection, choose the low noisevibration equipment and use the masking effect. They are of great advantage to dental clinics to i prove dental service and competitiveness.

• Journal of KSNVE
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• v.10 no.1
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• pp.41-48
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• 2000

Evaluation model for damage consciousness was established through the survey of 2,210 residents' consciousness on aircraft noise near Taegu Airport. There were none who replied that the level of the aircraft noise was as los as it was quiet. 77(3.5%) people replied the noise was normal, and 2,133(95.5%) people said it was noisy. As to the period of time when the aircraft noise occurred, 51%, 97%, 86%, 0.6% of the residents pointed out the morning time, the day time, the evening time, and the night time, respectively. Because of aircraft noise, 73%, 88%, 70%, 77%, 78%, and 33% of the residents felt it disturbing indoor conversation, telephoning, watching TV or listening to the ratio, reading or meditating, working, sleeping, and studying, respectively. It was examined that the bad effects of aircraft noise on the health were severe : 43% of the resident said they experienced embarrassment. 52% astonishment, 66% absence of mind, 61% heart-beating. 77% headaches, 78% earache, and 93% displeasure. For the survey of the residents' damage consciousness about aircraft noise, the level of aircraft noise was set as an objective variable, and gender, age, occupation. Education, the type of house, the structure of windows, the consciousness of settlement in the district, and the period of residence were set as explanatory variables. And the quantification theory I was applied to the analysis. The most influencing factor of the damage consciousness on aircraft noise was the education, the second occupation, the third age, the forth the consciousness of settlement, the fifth the period of residence, the sixth gender, the seventh the type of house, and the least influencing factor among them was the structure of windows. These findings will be a useful guideline when the government seeks to set up policies which will help solve the resident's noise problems near Taegu Airport.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.742-752
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• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.676-684
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• 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.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.633-638
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• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1153-1160
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• 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).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.240-246
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• 2019

The noise generated by construction machinery operating at construction sites is a major cause of environmental disputes with nearby residents. To reduce construction site noise, low noise construction machinery and low noise methods are recommended to be used first. In addition, the possible noise should be predicted and preventive measures suitable for the noise source should be taken. This study analyzed the sound power level of an excavator, which is used most frequently at construction sites. The sound power level of 297 excavators sold in Korea after 2008 were analyzed and the sound power level was classified according to the type, output (kW), and production site of the excavator engine based on the measured data. As a result, the sound power level decreased by 1 dBA depending on the change in engine type and the sound power level increased by approximately 3 dB (A) when the engine output was doubled. In addition, the sound power level was low in small-sized products of less than 55 kW for overseas products and medium and small-sized products of 55 to 104 kW for domestic products.