• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.393-398
• /
• 2006

This study is undertaken to evaluate the characteristics of cross contamination around exterior air-vents. A CFD analysis has been performed to calculate the cross contamination index for five exterior air-vents sizes according to the outdoor air velocity and separation distance of it. From the result of the numerical method, As the outdoor air velocity is increased, the cross contamination index is increased. on the contrary, as the separation distance of exterior air-vents is increased, the cross contamination index is decreased, additionally the cross contamination is affected by the aspect ratio of the size of exterior Air-vents.

• 한국수소및신에너지학회논문집
• /
• 제29권3호
• /
• pp.292-298
• /
• 2018

The contamination of photovoltaic (PV) cells reduces the incidence of sunlight and reduces the power generation output of PV cells. The main factor influencing the contamination of PV cells installed outdoors is the fine dust in the air, but the influence of temperature, humidity, rain and wind can be considered. In this paper, experiments on the contamination of PV cells according to the fine dust density, the temperature and humidity of air were investigated. As results of this study, the contamination area of PV cells increases with contamination time and cumulative fine dust density in the air. The contamination of PV cells increases when the temperature is low and the humidity is high. Also, as the contamination of PV cells is affected to the wind, the deviation of contamination area is happened.

• 한국초전도ㆍ저온공학회논문지
• /
• 제25권1호
• /
• pp.6-10
• /
• 2023

2 K superfluid helium cryogenic system is the crucial component of many large accelerators. When the cryogenic system is operating at 2K@3129Pa, many room-temperature parts are connected to superfluid helium via tubes. Air Leakage in these connections may lead to air contamination of the cryogenic system. Air contamination may cause equipment failure in cryogenic systems and, in extreme cases, render the entire accelerator system inoperable. Helium guard is a technique that guards against air contamination of these sub-atmospheric pressure connections in 2 K superfluid helium cryogenic system. This paper introduces a typical 2 K cryogenic distribution design for large accelerators, and make risk analysis of air contamination. Finally, the analysis of specific leakage points and detailed engineering design are presented, which may be used as a reference when designing of a 2 K superfluid helium cryogenic distribution system.

• Environmental Analysis Health and Toxicology
• /
• 제14권4호
• /
• pp.165-174
• /
• 1999

This study was conducted to analyze the priority of environmental problems in Korea by investigating the environmental professionals' perception. The delphi technique was applied to identify their risk perception towards some specific items related with pollution. A standardized questionnaire on environmental problems and their priorities was used to 74 subjects. In the questionnaire, the environmental problems were divided into the general ones,9 items, and the specific ones,30 items. Also, the perception was associated with two points of view which were the risk on general human health or ecosystem, and on the present situation in Korea. The priority of risk from general environmental problems on human health or ecosystem was analyzed in the order of 'water pollution', 'air pollution', 'soil contamination', 'waste', 'toxic chemical pollutants', 'food contamination', 'ocean contamination', 'odor pollution', and 'noise pollution'. The priority of risk on the present situation in Korea was analyzed in the order of 'water pollution','air pollution','waste','toxic chemical pollutants','food contamination','soil contamination','ocean contamination','odor pollution', and 'noise pollution'. And these priorities were significantly related with the characteristics of respondents such as sex, age, and major concerned area. However, for the first five priorities of risk from the specific environmental problems on human health or ecosystem, the environmental professionals agreed with 'automotive vehicle exhaust', 'domestic and industrial source pollutants to surface water', '$CO_2$nd g1oba1 warming effect','toxic air pollutant' and 'industrial source air pollution'. The priorities of risk on the present situation in Korea were similar to these results.

• 설비공학논문집
• /
• 제24권4호
• /
• pp.297-305
• /
• 2012

In recent large-scale semiconductor manufacturing clean rooms, the energy consumption of outdoor air conditioning systems to heat, humidify, cool and dehumidify incoming outdoor air represents about 45% of the total air conditioning load required to maintain a clean room environment. Therefore, the energy performance evaluation and analysis of outdoor air conditioning systems is useful for reducing the outdoor air conditioning load for a clean room. In the present study, an experiment was conducted to compare the energy consumption of outdoor air conditioning systems with a simple air washer, an exhaust air heat recovery type air washer and a DCC return water heat recovery type air washer. It was shown from the present lab-scale experiment with an outdoor air flow of 1,000 $m^3/h$ that the exhaust air heat recovery type and DCC return water heat recovery type air washer outdoor air conditioning systems were more energy-efficient for the summer and winter operations than the simple air washer outdoor air conditioning system and furthermore, the DCC return water heat recovery type one was the most energy-efficient in the winter operation.

• Journal of Radiation Protection and Research
• /
• 제38권4호
• /
• pp.234-236
• /
• 2013

비밀봉 방사성물질을 취급하는 시설에서 이들 물질에 의한 작업환경의 다소간의 오염은 피할 수 없다. 오염의 우려가 있는 작업환경에서 오염관리의 일차적인 목적은 방사성물질의 잠재적 체내섭취로 인한 영향이다. 본 논문은 보수적 가정과 간단한 계산에 의거하여 공기오염에 따른 방사성물질의 공기중 농도와 흡입에 의한 연간 섭취량을 산출한 후, 관련 고시에서 정하는 유도공기중농도와 연간섭취한도와 비교함으로써 종사자의 내부피폭 정도를 평가하는 절차를 제공한다. 제시된 절차는 공기중 방사성물질 측정 및 내부피폭 감시의 필요성, 적합한 방호용구의 착용, 배기설비 설계를 위한 정보 획득 등 공기오염과 종사자의 내부피폭 감시를 위한 실무적 요건을 판단할 목적으로 활용될 수 있다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.1306-1311
• /
• 2009

In recent semiconductor manufacturing clean rooms, in order to improve clean room air quality, air washers are used to remove airborne gaseous contaminants such as $NH_3$, SOx and organic gases from the outdoor air introduced into clean room. Meanwhile, there is a large amount of exhaust air from a clean room. From an energy conservation point of view, heat recovery is therefore useful for reducing the outdoor air conditioning load for a clean room. Therefore it is desirable to recover heat from the exhaust air and use it to reheat the outdoor air. In the present study, numerical analysis and experiment was conducted to simulate the amount of energy reduction of exhaust air heat recovery type air washer system. The present numerical results showed good agreement with the results of the experimental data.

• 설비공학논문집
• /
• 제25권2호
• /
• pp.55-63
• /
• 2013

For a large-scale semiconductor manufacturing clean room, the energy consumed in an outdoor air conditioning system to heat, humidify, cool and dehumidify incoming outdoor air is very large. In particular, the energy requirement to humidify outdoor air in the winter season is generally known to be high. Recently, in order to overcome the high energy consumption nature of a steam generator in a conventional steam humidification type outdoor air conditioning system, an air washer is often introduced instead of the steam generator in the outdoor air conditioning system, which can be called a water spray humidification type outdoor air conditioning system. Therefore, the assessment and comparison of the annual energy consumed in the steam humidification type and the water spray humidification type outdoor air conditioning systems deserves to be examined in order to reduce the outdoor air conditioning load of a clean room. In the present study, a numerical analysis was conducted to obtain the annual electric power consumption of the two outdoor air conditioning systems. It was shown from the comparison of the numerical results that the water spray humidification type outdoor air conditioning system can reduce about 30% of annual electric power consumption of the steam humidification type outdoor air conditioning system.

• 설비공학논문집
• /
• 제22권10호
• /
• pp.697-703
• /
• 2010

In recent semiconductor manufacturing clean rooms, air washers are used to remove airborne gaseous contaminants from the outdoor air introduced into a clean room. Meanwhile, there is a large amount of exhaust air from a clean room. From an energy conservation point of view, heat recovery is useful for reducing the outdoor air conditioning load required to maintain a clean room. Therefore it is desirable to recover heat from the exhaust air and use it to cool or heat the outdoor air. In the present study, numerical analysis was conducted to evaluate the recovered heat of an exhaust air heat recovery type air washer system, which is the key part of an energy saving outdoor air conditioning system for semiconductor clean rooms. The present numerical results showed relatively good agreement with the available experimental data.

• 반도체디스플레이기술학회지
• /
• 제19권2호
• /
• pp.37-44
• /
• 2020

In improving laser cutting of optical plastic films for mass production of optoelectronics display units, it is important to understand particle contamination over optical film surface due to fume particle generation and dispersion. This numerical study investigates the effects of downward and upward air flow motions on fume particle dispersion around laser cut line. The simulations employ random particle sampling of up to one million fume particles by probabilistic distributions of particle size, ejection velocity and angle, and fume particle dispersion and surface landing are predicted using Basset-Boussinesq-Oseen model of low Reynolds number flows. The numerical results show that downward air flow scatters fume particles of a certain size range farther away from laser cut line and aggravate surface contamination. However, upward air flow pushes fume particles of this size range back toward laser cut line or sucks them up with rising air motion, thus significantly alleviating surface contamination.