• 한국입자에어로졸학회지
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• 제18권3호
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• pp.51-59
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• 2022

In this work, virion concentration and its dose changes by HVAC and air cleaners were estimated in a subway station platform to control airborne infection of SARS-CoV-2. Collection efficiencies with particle size were measured for the air filter equipped in a HVAC in one subway station in Daejeon. Indoor PM_2.5 changes according to outdoor PM_2.5 with time were also measured to estimate air infiltration rate in the subway station platform. When infected persons generate virions by 10⁴, 10⁵, 10⁶, 3 × 10⁶ and 5 × 10⁶ h^-1 in a 2,400 m³ volume platform, the concentration and dose were estimated as 9, 92, 275 and 458 virions/m³ and 4, 43, 130 and 217 virions after 1 hour exposure, respectively. The concentration and dose were reduced by 70%, and 64%, respectively by operations of both HVAC (with a flow rate of 16,000 m³/h, MERV 11) and ten air cleaners(with total CADR 10,740 m³/h) compared to those without operation of both HVAC and air cleaners. However, virion dose in the platform was estimated to be too low at the general conditions due to a large space, a high air infiltration (3 h^-1) and a short residence time (usually < 10 mins) in the platform irrespective of the operations of HVAC or air cleaners. HVAC with filters and air cleaners would be more necessary in the concourse or shopping areas in the subway stations to reduce the infection dose from a few hundred to several tens virions in a hour.

• 한국환경과학회지
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• 제6권6호
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• pp.637-644
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• 1997

The purpose of thins study was to quantitatively determine the Indoor Infiltration of pollutants of outdoor origin. The relationship between Indoor and outdoor air is dependent, to a large extent. on the rate of k exchange between these two environments. Mean Indoor/outdoor ratios measured from thins study were: 0.70 for HNO3; 1.60 for HNO2: 0.56 far SOg: 1.30 for mf3: 0.96 for PM2.5(dP<2.5mm: 0.89 for SO4a': 0.87 for NO3· and 0.79 for NH4 'Mean Indoor concentrations for PMa s, SO4a., HNO9, NO3 and NIL' were similar to outdoor levels. Indoor HNO2 and mB3 values were h19her than outdoors. However, the Indoor level of SO2 was lower than ambient level.

• 한국임상수의학회지
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• 제21권4호
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• pp.413-415
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• 2004

A male Blue-fronted amazon parrot suddenly died after having a history of depression, anorexia and emaciation. At necropsy, numerous well-demarcated yellow to white firm nodules were scattered throughout the left caudal lung lobes and adjacent air sac. Histologically, the wall of air sac was significantly thickened due to necrosis and infiltration of large numbers of fungi and degenerated heterophils. Multifocal necrotizing granulomatous lesions with numerous fungal hypae as well as vasculitis and thrombosis were found in tl1e lung. The fungi had conidiophore, vesicle, phialides and conidia which were characteristic of Aspergillus sp. This is tl1e first report of mycotic air sacculitis and pneumonitis caused by Aspergillus in a parrot in Korea.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2009년도 춘계학술논문발표회 논문집
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• pp.110-119
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• 2009

A fire should be accompanied by the heat and smoke. However, smoke is considered main cause of heavy casualties. Smoke easily spreads away from the fire area to remote space and cause mortal wound for the resident. A technical way effectively protecting the life and property from the smoke is the smoke control system of the building. Pressurized air supply system can be considered to prevent the refuge area from the smoke infiltration that evacuate residents via evacuation route for life safety. This paper is related with performance estimation and the effectiveness of the pressurized air supply system through experiments.

• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.65-71
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• 2008

The purpose of this study is to investigate an airtightness of typical Korean detached houses with field measurements. Air leakage testings by means of blower door test in accordance with ASTM E79-8 were measured in 22 detached dwellings in Daejeon and Geumsan. The results showed that detached dwellings have an average airtightness with ACH50/20 (air chang per hour at a pressure difference of 50 Pa between inside outside) of 0.82 $hr^{-1}$ which is a higher range than for typical apartments and leakage class G by normalized leakage area of ASHRAE.

• Journal of Information Technology Applications and Management
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• 제30권6호
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• pp.17-29
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• 2023

In this paper, we aim to propose cyber security considerations and countermeasures for infrastructure and services in the UAM(Urban Air Mobility) Air Traffic Management field, which is one of the key elements of the UAM market that has not yet bloomed. Air traffic management is an important factor for safe navigation and social acceptance of UAM. In order to realize air traffic management, infrastructure and services based on solid network connectivity must be established. And for industries where connectivity is the core component, it can become an infiltration route for cyber threats. Therefore, cyber security is essential for the infrastructure and services. In detail, we will look into the definition of the existing air traffic management field and the cyber threats. In addition, we intend to identify cyber security threat scenarios that may occur in the newly designed UAM air traffic management infrastructure. Moreover, in order to study the cyber security countermeasures of the UAM air traffic management infrastructure, there will be analysis of the UAM operation concept. As a result, countermeasures applicable to the infrastructure and service fields will be suggested by referring to the cyber security frameworks.

• 한국분말재료학회지
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• 제7권4호
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• pp.205-211
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• 2000

Distribution of $Y_2BaCuO_5$ (211) Particles within $YBa_2Cu_3O_{7-x}/$ (123) grains of melt infiltration processed YBCO oxides was investigated. Processing parameters were a temperature, atmosphere (air and $O_2$) and initial 211 size. The 211 particles were distributed randomly within the 123 grains when the initial 211 size was large, while they made x-like pattern and/or butterfly-like patterns when the 211 size was small. The 211 patterns were more clearly observed in the samples prepared at higher temperatures and under $O_2$ atmosphere. The 211 distribution was explained in terms of the interfacial energy relationship among the solid, particle and melt.

• 한국농공학회지
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• 제35권1호
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• pp.29-39
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• 1993

A model for estimating daily effective rainfall of upland crops was developed. The infiltration process was described by Green-Ampt infiltration model developed by Chu(1978). The model considers delayed surface ponding and surface detention storage under a uniform soil profile. The Green-Ampt parameters, that is, average hydraulic conductivity and average capillary pressure head on a sandy loam soil were determined from field experiment using Air-entry permeameter developed by Bouwer(1966). The model was verified by comparing measured and simulated surface runoff. The ratios of effective rainfall to total rainfall for red pepper, soybean, sesame and Chinese cabbage were evaluated using Borg's root growth model( 1986) respectively. The followings are a summary of this study results; 1.In a sandy loam soil average hydraulic conductivity was 3.28cm/hr and average capillary pressure head was 3.00cm. 2.The root growth of upland crops could be expressed by Borg's root growth model successively. 3.The measured and simulated surface runoff was agreed well with each other. 4.As the rainfall amount was increased, the ratio of effective rainfall to total rainfall was decreased exponentially till a certain growing period.

• 한국지반공학회논문집
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• 제22권7호
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• pp.55-64
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• 2006

풍화 사면은 지속적인 강우로 인하여 얕은층에서 파괴가 일어나고 있다. 이러한 파괴들은 주로 강우 침투로 지표면에서의 습윤대의 형성과 이로 인한 흡수력의 감소에 기인한다. 본 연구에서는 대표적인 풍화사면인 화강 풍화토 및 편마풍화토에 대한 함수특성곡선의 건조-습윤 이력과 선행강우 조건을 활용하여 시간에 따른 불포화 침투 해석을 인공적인 강우 강도와 지속시간을 설정하여 실시하였다. 그 결과 풍화 사면의 불포화 침투는 깊이별로 선행 강우에 의한 초기 흡수력과 이력에 따른 불포화 투수계수에 많은 영향을 받는 것으로 나타났다. 또한 화강풍화토가 편마풍화토 보다 상대적으로 작은 공기 함입값, 잔류 흡수력, 그리고 습윤 전면 흡수력을 가지고 있으며 이력 loop가 작아서 침투에 대한 흡수력의 변화 반응이 매우 빠름을 확인할 수 있었다.

• 한국태양에너지학회 논문집
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• 제26권1호
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• pp.21-28
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• 2006

Changes in building construction methods and repairing of older buildings have reduced infiltration rate. Synthetic materials, release airborne particles and uneven healthy odor are increased. For preventing pollutants introduce fresh outdoor air into the building, simply letting fresh outdoor air into building, however, Is not a cost-effective way to ventilation. When additional ventilation is added to an existing HVAC system, the heating and cooling equipment, often cannot handle the increased load. A HRV provides a way to minimize in energy costs while introducing fresh air to a building. In this study, the economical research of HRV, made of three types of materials, are conducted. Heat recovering characteristics are studied at seasonal outdoor air conditions based on the outdoor air property condition at, Seoul in 2002. As a results, the average sensible effectiveness is 0.75 in the sensible heat exchanger and average total effectiveness is 0.65 in the total heat exchanger. The pay back period of the sensible heat exchangers are $3.2{\sim}3.5$ year and it of total heat exchanger is 2.2 years.