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실내외 환경조건 변화를 고려한 미세먼지 침입계수 및 침착률 산정 방법
박소우(Sowoo Park),구준모(Junemo Koo),송두삼(Doo Sam Song) 대한설비공학회 2020 대한설비공학회 학술발표대회논문집 Vol.2020 No.6
The outdoor Particulate Matter(PM) can penetrate into the room with the outside air through the gap of the building envelope, and the ratio of the concentration of PM entering the room from the inside and outside boundary is called the penetration coefficient. The introduced PM is deposited on the surrounding surface by gravity and airflow, and the amount of PM deposited per unit time is called a deposition rate. Since the penetration coefficient and deposition rate can fluctuate depending on the air exchange rate, it is important to measure it repeatedly according to the change in real-time air exchange rate. The purpose of this study is to present a method for estimating the penetration coefficient and deposition rate according to changes in indoor and outdoor environmental conditions(air exchange rate). The real-time air exchange rates were calculated by the trace gas decay method using the occupant-based carbon dioxide. Penetration coefficients and deposition rates were calculated using the discretized equations of the mass balance to minimize the error between the measured and estimated indoor PM concentrations. As a result of the measurement, the air exchange rates were fluctuated in the range of 0.094 ~ 0.476 h<SUP>-1</SUP> depending on the temperature difference between indoor and outdoor and the wind speed in the same room. The penetration coefficient showed the largest as 0.565 at the particle size of 1.0 ㎛, and decreased as particle size was larger or smaller than 1.0 ㎛. The penetration coefficient tended to decrease as the particle size increased. The deposition rate showed the smallest at a particle size of 0.5 ㎛(0.280), and decreased as the particle size increased.
코로나 바이러스(COVID-19) 공기 감염방지를 위한 실내 환기성능 지표로 CO₂ 적정 농도의 제안
박소우(Sowoo Park),송두삼(Doo Sam Song) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
Aerosols smaller than 5 μm in diameter are believed to play an important role in SARS-CoV-2 transmission and indoor infection. The Wells-Riley model widely used to estimate the probability of infection in indoor requires the measurement of ventilation rate or air change rate. There are many method to calculate the ventilation rate by measurement. However, these method has limitations in actual occupancy conditions. The aims of this study is to propose the ventilation performance control method for the prevention of COVID-19 infection indoors. In this study, based on the Wells-Riley model, a method for deriving an CO₂ concentration threshold for the prevention of SARS-CoV-2 airborne transmission through CO₂ monitoring in actual conditions was proposed. This methodology included the effect of virus deposition and viral inactivation. As a result, as the exposure time and number of occupants increase, the mean CO₂ concentration threshold increases, and deposition rate and viral inactivation increase the mean CO₂ concentration threshold. The mean concentration thresholds in school classrooms, restaurants, supermarkets and offices were 904, 763, 688, and 588 ppm, respectively.
재실자의 간헐적인 이동이 실내 공기교환율에 미치는 영향
박소우(Sowoo Park),구준모(Junemo Koo),송두삼(Doo Sam Song) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
Air exchange rate is a function of building characteristics, external environmental conditions (indoor/outdoor temperature difference and external wind velocity), and occupant behavior (e.g., window- or door-opening). In particular, air exchange due to door-opening behavior occurs unintentionally due to movement of occupants, and occurs in all buildings. The intermittent movement of occupants during the occupancy period can increase the average air exchange rate compared to the non-occupant period. This study aims to quantitatively calculate the change in air exchange rate depending on room occupancy. The air exchange rate according to the number of occupants was calculated using the CO₂ generated by occupants for the office. CO₂ concentration was collected at three indoor points and one outdoor and hallway point. As a result, the air exchange rate during the occupancy period significantly increased compared to the air exchange rate during the non-occupancy period, and the number of occupants per hour was proportional to the air exchange rate. The air exchange rate during the occupancy period significantly increased compared to the air exchange rate during the non-occupancy period in the condition that the external environmental conditions are controlled. Also, the enter or leaved persons per hour was proportional to the air exchange rate. That is, during the occupancy period, additional air exchange occurred due to entry and exit, resulting in a higher air exchange rate compared to the non-occupancy period.
재실자 활동도를 고려한 학교 교실 미세먼지 농도 예측 모델 작성
박소우(Sowoo Park),구준모(Junemo Koo),송두삼(Doo Sam Song) 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2021 No.6
School classrooms are places where students, who are health-sensitive, spend a lot of time in a day, so particulate matter (PM) in classrooms has a significant influence on students health. The PM concentration in school classrooms can be formed from both the penetration from the outside air and the generation/resuspension of the indoor students activities. Previous studies conducted a macroscopic analysis of the indoor PM concentration based on occupancy status, however, the indoor PM penetration and generation characteristics may change every minute depending on the students activity and ventilation status. The aims of this study is to predict the PM concentration in the classroom by quantifying the penetration from the outside air and the generation from indoor activities according to the school occupancy schedule. Long-term measurements for PM concentration were conducted for about four months in 5 classrooms. The results showed that the inflow of external PM tends to decrease as the particle diameter increases when the door/window is closed. However, when students move through the door, the inflow of external PM with large particle size increased. Besides, the indoor PM generation rate increases as the particle diameter increases and particles with a diameter of 3 μm or more were generated by the student activities. Lastly, on days when the outside PM concentration was high, the indoor PM concentration was also high due to not only the infiltration effect, but also students entering and exiting.