• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.862-865
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• 2004

The system air conditioner has an outdoor unit and a number of indoor units, which connected by several long pipes. In comparison with building HAVC system, the system air conditioner doesn't need lots of facilities, such as control of room, cooling tower, etc. At the beginning stage for the market of the system air conditioner, its main application was a school which size is small to use the building HAVC and large to use home air conditioning system, such as PAC (package air conditioner), RAC (room air conditioner). Therefore, because of the advantages of the system air conditioner mentioned above, the market is expanded rapidly. Since it is difficult to evaluate the noise caused by the system air conditioner because it has to be implemented before the finish of construction, the prediction or estimation of the noise by using CAE technology should be very important. In this research, using a commercial code, RAYNOISE, the noise is estimated to improve the design of building.

• 한국소음진동공학회논문집
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• 제20권10호
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• pp.968-975
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• 2010

The high interest for the ground vibrations which is caused by the train service is risen. When the trains are passed, a serious force is applied to ground and the caused vibration is propagated to the area of the building by the ground and rocks. This vibration comes to feel in the residents with the direct vibration, it is radiated in sound. The caused vibration and radiated sound affect the human's life, and this vibration brings about the operation interruption of the equipment which is sensitive to the vibration, or will bring about the structural damage of the building. In this study, the effect of the vibrations caused by the passing trains on the railway station and buildings is investigated by vibration measurement. Indoor and outdoor measurement is carried out by each trains.

• 한국컴퓨터정보학회논문지
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• 제19권5호
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• pp.37-42
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• 2014

본 연구의 목적은 170 dB 수준의 충격 소음원에서 주파수별 귀마개의 차음성능을 확인하고, 주파수 특성과 패턴 형상을 분석하는데 있다. 충격 소음에서의 Combat Arm Earplug와 3M Form types 1100 Earplug의 주파수별 귀마개 차음성능을 산출하였다. 차음성능을 확인하기 위해서 B&K Head and Torso Simulator와 Ear Simulator를 제작하여 충격 소음원의 주파수별로 차음성능을 비교하였다. 기존의 연구들은 충격 소음원이라 할지라도 대부분 140 dB 수준의 고충격 소음원이였으나, 본 연구는 그보다 더 높은 수준의 충격 소음원이라는 특징을 가지고 있다. 연구결과, 주파수별 충격소음의 차음효과는 평균 28.58 dB 인 것으로 나타났다.

• 한국주거학회논문집
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• 제8권2호
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• pp.71-84
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• 1997

The Purpose of this study is to estimate how inclination to move can be appeared by understanding the cognition of a resident on stress due to the residential environment. 240 housewives living in Chiniu were Questioned statistical analysis were used with factor analysis, F-test. Duncan's Multiple range analysis, stepwise regression analysis and stepwise discriminant analysis, The result were summarized as follows 1) The stress of residential environment were clissified by six factors indoor facility, educational environmental. indoor structure, air Pollution noise, traffic convenience. 2) The extent of a stress from residential environment was significantly different in the socio-demographic variable and housing-related variable. 3) The stress of residential environment were affected by the direction of house. 4) The variable discriminating inclination to move were the stress of residential environment(air Pollution). an educational level, the type of housing possession, residential Period and the size of house.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.289-294
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• 2002

In this study, performance, flow characteristics and noise of a cross-flow-fan system, used in indoor unit of the split-type air conditioner, were predicted by computational simulation. Triangular elements were used to mesh the calculation domain and quadrilateral elements were attached to the blade surfaces and walls to enhance the simulation quality. The unsteady incompressible Wavier-Stokes equations were solved using a sliding mesh technique on the interface between rotating fan region and the outside. Two stripes of velocity stream inside the cross-flow-fan were shown - the one was due to the eccentric vortex and the other was due to the normal entrance flow. As the flow rate increased, the center of the eccentric vortex moved toward the inner blade tip and rear-guide, and the exiting flow still had velocity variation along the stabilizer, which can increase the noise level. The acoustic pressure was calculated by using Lowson's equation. From the calculated acoustic pressure, it was found that the trailing edge is a dominant of acoustic generation.

• 한국산업보건학회지
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• 제34권1호
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• pp.1-7
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• 2024

Objectives: The study was performed to investigate characteristics of hazardous factors regarding chemical(liquid lime) tank dredging workers by case survey. Methods: Field data such as working condition, MSDS and respirators applied to chemical tank dredging work were analyzed and the work environmental factors of noise and indoor air quality were measured to compare existing data with actual work situations. Results: No health hazards to workers due to working conditions were confirmed during dredging work inside the chemical storage tank. All air quality measurement data during dredging work satisfied the management standards, and there were no by-products. During dredging work, there was a significant change in noise depending on the type of work, but considering the noise reduction rate(NRR) of the earplugs worn by workers, there was no actual health hazard due to noise exposure. Conclusions: A fit test for respirator and the expiration date of the safety helmet should be observed to ensure an appropriate level of safety and health for dredging workers in the chemical storage tank.

• 한국소음진동공학회논문집
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• 제16권2호
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• pp.141-148
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• 2006

Korean traditional houses have been evolved and developed in many years, adopting the natural environment to control exterior conditions. These control method are various Passive system of using natural materials, considering micro climate, building lay out, and these system are much natural and ecological to make the comfortable indoor climate than active systems of the present houses. This study aims to analyzed the acoustical characteristics of Korean traditional houses varied with lay out and floor plan to reflect the way of control for environmental condition. The reverberation time and level difference between rooms of the main living room and other main floored room, master room and kitchen are measured in each houses. As a result, the reverberation time of Korean traditional rooms are below 0.6 second, and the sound insulation performance of Korean traditional door are mostly very low grade with D-15. The level difference between rooms are low grade not to meet minimum class except between main living room and master room away from main living building. These above results show that our traditional house are much more emphasized seeking visual privacy of rooms than aural privacy.

• 한국입자에어로졸학회지
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• 제6권1호
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• pp.9-20
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• 2010

This study examined the concentration level of the major air pollutants in public transportation. The study was conducted between February 2009 and March 2008 at Suwon-Yeosu line in Korea. $PM_{10}$ concentration level was $100{\mu}g/m^3$ on average. The $PM_{2.5}$ to PM10 ratio in transport is 0.37, which was lower than the results published by other researches. The result also demonstrated that outdoor $PM_{10}$ concentration was about 56~60% level compared to that of the cabin. $CO_2$ concentration level in the cabin was 1,359ppm, which does not exceed 2,000ppm, which is the guideline concentration level according to the Ministry of Environment. $CO_2$ concentration level in the cabin was $CO_2=23.4{\times}N+460.2$, and about 23.4ppm in $CO_2$ concentration level increased every time one passenger was added on. The experiment conducted on the train demonstrated that the average $PM_{10}$ concentration level was $100{\mu}g/m^3$ in case of the reference cabin while average $PM_{10}$ concentration level of the modified vehicle was $68{\mu}g/m^3$. Likewise, effect of the particle reduction device for the reduction of $PM_{10}$ concentration level was approximately 21%. Meanwhile there was almost no difference in the concentration level between reference and modified cabin in case of $PM_{2.5}$. Using zeolite as an adsorbent was made to reduce the $CO_2$ concentration level in the cabin. Number of passengers was factored in, to calculate the effect of the adsorption device, which demonstrated that about 36% of $CO_2$ concentration level was reduced in the modified cabin effect of the $CO_2$ reduction device. This research analyzed the current status concerning the quality of air in the public transportation and technologies were developed that reduces major air pollutants.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.78-85
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• 2011

In this study, an underfloor air distribution(UFAD) system installed on the S. office building was evaluated for its indoor environmental quality performance. Field measurement and survey were conducted for the overall POE(Post Occupied Evaluation). PMV(including temperature, humidity, air velocity and globe temperature) and several environmental components were measured while thermal comfort, thermal sensation, acoustical environment and others. were investigated through survey. Except for the direct upper part of the air supply diffuser on the floor, the indoor velocity was less than 0.25m/s, which has been suggested by ASHRAES tandard 55 as the limit for thermal comfort. MRT of the perimeter zone of the room showed a higher value than that in the interior because of the introduced solar radiation through the building envelope. PMV was generally maintained in the range of thermal comfort (from -0.5 to +0.5), though it weighted to the warm side. It was reported to have 61% positive response on thermal comfort and 55% on neutral thermal sensation. The results of each survey item showed some gender-based differences. Specifically, female respondents had higher degree of dissatisfaction with indoor air cleanness and acoustical privacy. The working surface showed more than 400 lux and the equivalent noise level showed less than 50 dB(A). In conclusion, the results of the measurement and survey showed good agreement. Indoor environmental quality of the subject office room where the UFAD system was installed showed an overall excellent performance.

• Asian Journal of Atmospheric Environment
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• 제8권1호
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• pp.35-47
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• 2014

The purpose of the study is to evaluate the pollution level (gaseous and particle phase) in the public facilities for the PAHs, non-regulated materials, forecast the risk level by the health risk assessment (HRA) and propose the guideline level. PAH assessments through sampling of particulate matter of diameter < 2.5 ${\mu}m$ ($PM_{2.5}$). The user and worker exposure scenario for the PAHs consists of 24-hour exposure scenario (WIES) assuming the worst case and the normal exposure scenario (MIES) based on the survey. This study investigated 20 PAH substances selected out of 32 substances known to be carcinogenic or potentially carcinogenic. The risk assessment applies major toxic equivalency factor (TEF) proposed from existing studies and estaimates individual Excess Cancer Risk (ECR). The study assesses the fine dusts ($PM_{2.5}$) and the exposure levels of the gaseous and particle PAH materials for 6 spots in each 8 facility, e.g. underground subway stations, child-care facilities, elderly care facilities, super market, indoor parking lot, terminal waiting room, internet caf$\acute{e}$ (PC-rooms), movie theater. For internet caf$\acute{e}$ (PC-rooms) in particular, that marks the highest $PM_{2.5}$ concentration and the average concentration of 10 spots (2 spots for each cafe) is 73.3 ${\mu}g/m^3$ (range: 6.8-185.2 ${\mu}g/m^3$). The high level of $PM_{2.5}$ seen in internet cafes was likely due to indoor smoking in most cases. For the gaseous PAHs, the detection frequency for 4-5 rings shows high and the elements with 6 rings shows low frequency. For the particle PAHs, the detection frequency for 2-3 rings shows low and the elements with 6 rings show high frequency. As a result, it is investigated that the most important PAHs are the naphthalene, acenaphthene and phenanthrene from the study of Kim et al. (2013) and this annual study. The health risk assessment demonstrates that each facility shows the level of $10^{-6}-10^{-4}$. Considering standards and local source of pollution levels, it is judged that the management standard of the benzo (a)pyrene, one of the PAHs, shall be managed with the range of 0.5-1.2 $ng/m^3$. Smoking and ventilation were considered as the most important PAHs exposure associated with public facility $PM_{2.5}$. This study only estimated for inhalation health risk of PAHs and focused on the associated cancer risk, while multiple measurements would be necessary for public health and policy.