Ventilation devices and room air cleaners can be used to remove indoor contaminants from indoor air. Generally, room air cleaners are rated according to clean air delivery rate (CADR). However, a similar metric for ventilation has not been used to be compared with CADR of room air cleaner. The CADRs and cost-effectiveness metrics (CADR/kw) of ventilation devices and room air cleaners were newly defined and theoretically compared for a child care center. The results indicate that the CADRs of room air cleaner were greater than that of ventilation. A higher collection efficiency for the particles guaranteed a higher CADR for ventilation. Ventilation filter had a performance that exceeds MERV11 should be used to effectively control the indoor particle concentration. The stand alone type air cleaner was found to have the best performance in the cost-effectiveness. The reason for this is that the effective air cleaning ratio of the stand alone type air cleaner is higher than that of the others and the power consumption of the stand alone type air cleaner is lowest.

Numerical analysis was conducted to characterize particle deposition on a heated rotating semiconductor wafer with respect to wafer diameter. The particle transport mechanisms considered in this study were convection, Brownian diffusion, gravitational settling, and thermophoresis. The averaged particle deposition velocities and their radial distributions on the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference at rotating speeds of 0 and 1000 rpm, wafer diameters of 100, 300 mm and wafer heating of =0 and 5K. It was observed from the numerical results that the averaged deposition velocities on the upper surface increase, when the wafer diameter confirms increase. The comparison of the present numerical results with the available experimental results showed relatively good agreement between different studies.

From December 2014 to November 2015, an automatic weather system (AWS) was installed over a wide road of Daegu to continuously measure meteorological factors and surface temperature. We investigated the effective operating period of the clean-road system using the daily maximum and minimum air and asphalt surface temperatures, with the aim of creating an optimum thermal environment. The clean-road system was installed over a part of the broad way of Dalgubul(Dalgubul-Daero) by Daegu Metropolitan City in 2011. Until now, the clean-road system has been operated from the middle of April to the end of September. We assumed that it was desirable that the clean-road system could be operated when the discomfort index was above 55. In conformity with the conditions, we concluded that the optimum operation period of the clean-road system is from the end of March to about the middle of October.

To investigate thermal environment and effect of clean-road system over a broad way, we conducted the filed meteorological observation during 12~13 August 2014. The clean-road system was employed over a part of the broad way of Dalgubul(Dalgubul-Daero) by Daegu Metropolitan city in 2011. The clean–road system in general is operated two times(4 am, 2 pm) during summertime. In case of scorching alert, the system is operated 3 times a day(4 am, 2 pm and 4 pm). To evaluate the present thermal condition and the improvement effects due to the system, we analyzed the time variation of discomfort index and WBGT(wet-bulb and globe temperature). WBGT was more than 25 during 8 a.m. ~ 9 p.m. And discomfort index was more than 75 during 8 a.m. ~ 11 p.m. The thermal improvement effect of the clean-road system was restrictive during daytime.