Ventilation methods to prevent the spread of airborne pathogens from teachers to students

정창헌,Hwang Seok-Ho,Park Beungyong 대한설비공학회 2023 International Journal of Air-Conditioning and Refr Vol.31 No.1

This study investigates different ventilation systems to prevent the spread of airborne pathogens from teachers in an elementary school classroom setting. The analyzed systems include a general mechanical ventilation system and a hybrid ventilation system. The hybrid ventilation system used a combination of natural ventilation, general mechanical ventilation, and local mechanical ventilation systems. For natural ventilation, wind velocities of 1.1 m/s and 0.11 m/s were considered. To analyze the patterns of the spread of airborne pathogens, the indoor airflow patterns and concentrations of airborne pathogens (passive scalar) were examined using Star-CCM + . Comparing the methods confirmed that natural ventilation was more effective than general mechanical ventilation in removing the airborne pathogens discharged from the teacher. The proposed hybrid ventilation method with combined natural and mechanical ventilation also showed promise in removing airborne pathogens. However, for natural ventilation with low wind velocity, the buoyancy effect around the occupants creates airflow vortices in the front of the classroom which spread airborne pathogens from the teacher toward the students seated in the front of the classroom. Furthermore, operating a local ventilation system close to the teacher reduced the spread of airborne pathogens that occurred under natural ventilation conditions with low wind velocity.

캠퍼스 건축물 기밀성 향상을 통한 냉난방에너지소비량 저감효과 분석

정창헌,박병용 대한건축학회지회연합회 2016 대한건축학회연합논문집 Vol.18 No.2

본 연구의 목표는 캠퍼스 내 건축물의 기밀성능을 향상시킴에 따른 냉난방 에너지 저감효과를 분석하는 것이다. 분석은 에너지 시뮬레이션 툴인 TRNSYS를 이용하였다. 입력 데이터는 경남지역 G대학의 실제 운영 조건을 고려하여 결정하였다. 대상건물의 측정된 ACH50 값은 6.8~23.2 ACH 범위에 있었다. 해석의 주요 변수는 측정된 기밀성능을 반영한 침기량(ACH50/20)으로 설정되었다. 해석결과에 따르면 건축물의 기밀성능을 강화함에 따라 냉난방부하가 감소되는 것을 확인할 수 있다. 연간 CO2 배출량은 침기량을 0.6 ACH (ACH50 조건: 12 ACH)에서 0.4 ACH (ACH50 조건: 8 ACH)로 감소시킬 때 연구실에서 8%, 강의실에서 6% 감축되는 것으로 나타났다. 이러한 결과는 캠퍼스 건물의 기밀성능을 향상시킴으로써 에너지 효율이 향상될 수 있는 것을 의미한다. The purpose of this study is to evaluate the heating and cooling energy reductions by enhancing air-tightness of campus buildings. The analysis is performed by using energy simulation tool, TRNSYS. The input data are determined by actual operation data from G university in Gyeongnam. The measured ACH50 value of target building ranges from 6.8~23.2 ACH. The main variable of simulation is infiltration rate (ACH50/20) reflecting measured air-tightness. The simulation results show that heating and cooling load can be reduced by enhancing air-tightness of building. The estimated reductions of CO2 emissions of private research room and lecture room are 8% and 6% respectively when the infiltration rate reduced from 0.6 ACH(ACH50: 12 ACH) to 0.4 ACH(ACH50: 0.8 ACH). The results show the improved energy efficiency of campus buildings by air-tightness enhancement.

재실 패턴과 재실자 신체적 특징을 고려한 건축물 용도 별 공기전파감염확률 분석

정창헌 한국건축친환경설비학회 2019 한국건축친환경설비학회 논문집 Vol.13 No.2

This study analyzed the airborne infection risk of various building types by simulation. The airborne infection risk reflected the occupancy pattern and occupants’ physical Characteristics. The comparative study explicitly shows the exposure time to airborne pathogen determined by occupancy pattern significantly impacts to the airborne infection risk. In kindergarten, children’s increased breathing rate and low infiltration rate of building can cause increased airborne infection risk. Elderly facilities show the highest airborne infection risks for the longest residency hours and low ventilation rates.

캠퍼스 건물 유형에 따른 중간기 실내 열쾌적성 분석

정창헌,황석호,박병용 대한건축학회지회연합회 2014 대한건축학회연합논문집 Vol.16 No.4

본 연구의 목적은 중간기 동안 대학캠퍼스 건축물 실내의 열적 쾌적성을 팡악하는 것이다. 건물의 에너지 소비량은 재실자의 열적인 감각에 의해 영향을 받는다. EHP시스템은 캠퍼스 내 건축물에서 실내온도 조절을 위해 사용된다. 그러나, 실내 공기온도가 적정수준에 있더라고 실내의 열쾌적성은 벽체나 구조체의 표면온도에 따라 달라질 수 있다. 본 연구는 실내 열쾌적성의 변화와 잠재적인 난방 수요에 대하여 분석하였다. PMV가 열쾌적의 대표적인 지표로 사용되었다. 총 9개 실의 열적 조건이 측정되고 분석되었다. 그 결과로 축열체의 과도한 노출이 있거나 북향인 몇몇실은 실내의 쾌적성이 부적합한 것으로 나타났다. 본 연구를 통해 캠퍼스 내 건물의 특징에 따라 불필요한 잠재적 난방 수요가 있음을 확인할 수 있었다. The purpose of this study is to identify the thermal comfort of the buildings in campus during intermediate season. Energy consumption in building can be affected by the thermal sensation of the occupants. Electric heat pump that is recently used in campus buildings controls indoor temperature. However, thermal comfort can be vary by the effects of space conditions such as surface temperature of wall and other construction even though indoor air temperature is appropriate. This study focuses on the variation of the indoor thermal comfort and resulting potential of heating requirement. We determined indoor thermal comfort of building in campus during the intermediate season. PMV is used as the representative indicator. Indoor thermal condition of totally 9 rooms are determined and analyzed. As a result of field measurements, several rooms with inadequate thermal comfort status are found where the exposure to thermal mass is excessively high or the orientation of the room is north. The potential of unnecessary heating requirement by the building properties in campus is identified by this study.

시뮬레이션을 이용한 지하주차장 이중벽체 중공층 환기에 의한 표면결로 발생시간 감소 가능성 분석

정창헌,류성룡 대한건축학회지회연합회 2014 대한건축학회연합논문집 Vol.16 No.5

본 사전적인 연구는 지하주차장의 중공벽에 환기를 수행할 때, 표면결로의 저감 가능성을 분석하는 것을 목표로 한다. 본 연구는 지중에 면한 벽체의 표면온도와 결로가능성을 시뮬레이션으로 파악하는데 초점을 두고 있다. 에너지 시뮬레이션 툴인 ESP-r이 분석에 사용되었다. 기후데이터와 지중토양온도는 서울의 것이 사용되었으며, 벽체 중공층의 환기량은 0.1 ACH부터 9 ACH까지 변화되었다. 그 결과로 다소 낮은 환기량 만으로도 지하 2~3층 레벨에서 표면결로 가능성(시간)은 약 7.4~22.4% 감소하였다. 그러나 본 연구는 내부발열 및 벽체의 기밀등 불확정성이 있는 요인들을 배제한 이상적인 조건에서 수행되었기 때문에 향후 추가적인 연구 수행이 필요하다. The purpose of this preliminary study is to identify potential of the surface condensation prevention at the cavity wall in the underground parking lot when the cavity space of the wall is ventilated. The study focusing on the identifying the changes of condensation risk and surface temperature of the underground wall system facing soil by simulation. The energy simulation tool, ESP-r is used for the analysis. The climate data and underground soil temperature of SEOUL is used. The ventilation rate of the cavity space was changed from 0.1 ACH to 9 ACH. As the results of the simulation, surface condensation risk(hours) was reduced by 7.4~22.4% at the wall in second and third basement level by the cavity ventilation with relatively low ventilation rates. However, this study has limitation that analysis did not reflect the uncertain variables such as air leakage or internal heat gain and requires further investigation.

구들을 이용한 이동식 찜질시설의 실내 일산화탄소 농도 분석

정창헌,김서희,이은빛 한국생활환경학회 2019 한국생활환경학회지 Vol.26 No.5

The survey is performed to identify CO concentrations in movable sauna facilities using Gudeul. Various operation modes of movable sauna facilities are considered for the determination of CO concentration. The results of study as follow. At first. CO concentration diminished when the fuel input reduced. Secondly, CO concentration in unit of complex plan type is higher than that of simple plan type. Finally, natural ventilation can be the suitable solution for the reduction of CO concentration in the target facility.

Combination of Mechanical Ventilation and Ceiling Fin to Reduce Airborne Infection Risk

정창헌 한국생활환경학회 2023 한국생활환경학회지 Vol.30 No.1

This study evaluated the effects of various combinations of ventilation system and ceiling fin implementations for the prevention of airborne infections. The computational fluid dynamics program, STAR-CCM+, was used to analyze the airborne infection risk. The results indicate that implementation of ceiling fins with conventional mechanical ventilation and with exhaust diffuser at the center of the room reduced airborne infection risk. However, other cases with implementation of ceiling fins showed an increased risk at the breathing level (1.0 m height from the bottom). It is concluded that the application of ceiling fins can be both advantageous and disadvantageous depending on the types of combinations and all aspects should be carefully considered before implementation.

초등학교 학급 수를 이용한 연간 에너지소비량 모델 구축에 대한 탐색적 연구

정창헌,황석호,김지영 한국생활환경학회 2023 한국생활환경학회지 Vol.30 No.2

This study investigated exploratory research on energy consumption model of elementary schools by using an explanatory variable, number of classes and responsive variable, total annual energy consumption. Totally 18,539 data set of energy consumption in elementary schools are acquired for the analysis. After excluding abnormal data, 18,363 data set was used for the least square method for number of classes and total annual energy consumption. As the result of the study, the developed linear regression model is as follow: Annual total energy consumption (TOE) = 2.6259·X + 15.5 (X: number of classes). The coefficient of determination of this model is 0.7336. The derived coefficient of determination is slightly lower than required value of 0.75 by ASHRAE 2013. However, considering various conditions of 18,363 elementary schools, the derived model is thought to be meaningful enough.

Implementation of Ceiling Fin to Prevent the Spread of Airborne Pathogens by Buoyancy Effect

정창헌,황석호,박병용 한국생활환경학회 2022 한국생활환경학회지 Vol.29 No.3

Physical barriers such as partitions can reduce airborne infection by preventing aerosol or droplets exhaled by one person from entering the breathing zone of another. However, if buoyancy effect occurred in a natural room, airborne pathogens rise vertically and spread horizontally. So, this study suggested ceiling fin system to prevent the spread of airborne pathogens due to buoyancy effect and investigated the effect of the ceiling fins in preventing the spread of airborne pathogens by STAR-CCM+ (computational fluid dynamics software). As the results of the study, the ceiling fins prevented the airflow recirculation around the ceiling. Also, implementation of ceiling fins reduced airborne pathogen concentrations (passive scalar concentrations of the simulation model) not only at breathing zone but also in the entire room by 14% and 11.7% respectively. These results indicate that implement of the ceiling fins to delay in spread and mixing of airborne pathogens in a room.

환기량 및 감염자 분리시점이 초등학교 내 공기전파감염확률에 미치는 영향 분석

정창헌 한국건축친환경설비학회 2023 한국건축친환경설비학회 논문집 Vol.17 No.6

In this study, ventilation methods and quarantine methods for infected persons were evaluated as measures to reduce airborne infections in elementary schools. The minimum ventilation rate by mechanical equipment was calculated based on 20 people. As a result of the study, it was found that the minimum ventilation using mechanical ventilation has limitations in preventing the spread of airborne infection. However, it has been shown that securing a natural ventilation of more than 10 ACH throughout the day can effectively prevent the spread of airborne infection, but it is inevitably a limited alternative depending on the characteristics of the building. On the other hand, rapid isolation of infected persons has been shown to be very effective in preventing the spread of airborne infections. It is noteworthy that if an infected person can be isolated immediately after the first class, the spread of airborne infection can be effectively prevented even in everyday situations without wearing a mask.