Search Results (4)

PM_2.5, a critical air pollutant, requires health-conscious management, with concentrations varying across regions due to diverse sources. This study, conducted in South Korea in 2021, employed the geographically weighted regression model to analyze the spatiotemporal correlations of PM_2.5 with O₃ and the normalized difference vegetation index (NDVI). Regional differences in the correlation between PM_2.5 and O₃ were observed, influenced by common precursors (SOx, NOx, and volatile organic compounds (VOCs)), seasonal temperature variations, and solar radiation differences. Notably, PM_2.5 and O₃ exhibited a heightened regression coefficient in summer, emphasizing the need for specific management targeting VOCs and NO₂. The interplay between PM_2.5 and NDVI revealed a negative overall impact but a positive effect in the central region of Korea, suggesting vegetation’s role in the PM_2.5 concentration increase due to atmospheric stagnation caused by mountain ranges. These findings enhance our understanding of PM_2.5 distribution mechanisms, highlighting the need for tailored policies in each region for effective concentration reductions. Full article

Musculoskeletal disorders and the stagnation of sitting are among the side effects of excessive sitting in awkward sitting positions. In this study, a developed chair attachment cushion design with an optimal air blowing technique is proposed to eliminate the negative side effects of prolonged sitting. Instantaneously reducing the contact area between the chair and its occupant is the fundamental goal of the proposed design. The fuzzy multi-criteria decision-making approaches represented by FAHP and FTOPSIS were integrated to evaluate and select the optimal proposed design. An ergonomic and biomechanics assessment of the occupant’s seating position while employing the novel safety cushion design was validated using simulation software (CATIA). Sensitivity analysis was also used to confirm the design’s robustness. Results show that the manual blowing system using an accordion blower was the optimal design concept based on the selected evaluation criteria. In fact, the proposed design provides an acceptable RULA index value for the examined sitting postures and performed very safely in the biomechanics single action analysis. Full article

Since air quality has a great influence on students’ health and learning ability, enhancing air quality in classrooms is important. Currently, widely distributed ventilation systems operate by moving airflow horizontally from ventilation inlets and outlets on the ceiling. This method can reduce the average pollution in a space by diluting it through air exchange; however, it is limited regarding homogeneous cleanliness due to air stagnation at some locations. Therefore, in this study, a new ventilation system was devised to improve indoor air quality and spatial homogeneity by installing ventilation inlets on the ceiling and numerous outlets on the floor, creating a vertical airflow in the interior space; this system was then applied to a middle school classroom. Using the age of air as an index, air quality improvement between the existing and newly designed ventilation systems was compared. In the classroom with the existing ventilation system, the age of air was low in the area near the ventilation inlets, while air congestion areas were widely distributed and air age was high near the outlets. Conversely, in the vertical airflow classroom, the average age of air was approximately 15% lower than that with the existing ventilation system, and the deviation of air age for each position in the classroom space was also reduced, showing a uniform air age distribution. Therefore, the vertical airflow ventilation system proposed in this study can be an effective ventilation scheme for enhancing and homogenizing indoor air quality. Full article

In the recent decade, the North China Plain (NCP) has been among the region’s most heavily polluted by PM_2.5 in China. For the nonattainment cities in the NCP, joint pollution control with related cities is highly needed in addition to the emission controls in their own cities. However, as the basis of decision-making, the spatial characteristics of PM_2.5 among these cities are still insufficiently revealed. In this work, the spatial characteristics among all nonattainment cities in the northern part of the North China Plain (NNCP) region were revealed based on data mining technologies including clustering, coefficient of divergence (COD), network correlation model, and terrain and meteorology analysis. The results indicate that PM_2.5 pollution of cities with a distance of less than 180 km exhibits homogeneity in the NCP region. Especially, the sub-region, composed of Xinxiang, Hebi, Kaifeng, Zhengzhou, and Jiaozuo, was strongly homogeneous and a strong correlation exists among them. Compared with spring and summer, much stronger correlations of PM_2.5 between cities were found in autumn and winter, indicating a strong need for joint prevention and control during these periods. All nonattainment cities in this region were divided into city-clusters, depending on the seasons and pollution levels to further helping to reduce their PM_2.5 concentrations effectively. Air stagnation index (ASI) analysis indicates that the strong correlations between cities in autumn were more attributed to the transport impacts than those in winter, even though there were higher PM_2.5 concentrations in winter. These results provided an insight into joint prevention and control of pollution in the NCP region. Full article