This study analyzed the changes in particulate matter concentrations according to land-use over time and the spatial characteristics of the distribution of particulate matter concentrations using big data of particulate matter in Daejeon, Korea, measured by Private Air Quality Monitoring Smart Sensors (PAQMSSs). Land-uses were classified into residential, commercial, industrial, and green groups according to the primary land-use around the 650-m sensor radius. Data on particulate matter with an aerodynamic diameter <10 µm (PM10) and <2.5 µm (PM2.5) were captured by PAQMSSs from September‒October (i.e., fall) in 2019. Differences and variation characteristics of particulate matter concentrations between time periods and land-uses were analyzed and spatial mobility characteristics of the particulate matter concentrations over time were analyzed. The results indicate that the particulate matter concentrations in Daejeon decreased in the order of industrial, housing, commercial and green groups overall; however, the concentrations of the commercial group were higher than those of the residential group during 21:00–23:00, which reflected the vital nighttime lifestyle in the commercial group in Korea. Second, the green group showed the lowest particulate matter concentration and the industrial group showed the highest concentration. Third, the highest particulate matter concentrations were in urban areas where commercial and business functions were centered and in the vicinity of industrial complexes. Finally, over time, the PM10 concentrations were clearly high at noon and low at night, whereas the PM2.5 concentrations were similar at certain areas.

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We developed a simple method of producing metal oxide nanoparticles by reacting a polyamic acid (PAA) with Cu or Sn metal films. Respective particle size, distribution, and morphology were characterized by transmission electron microscopy (TEM). The morphology of metal oxides dispersed in the polyimide is different in Cu and Sn metal films. The Cu2O particles were formed by the dissolution reaction between the polyamic acid and the Cu films. During curing, PAA dehydrates and converts to polyimide, accompanied by precipitation of Cu2O particles. The synthesized Cu2O particles were randomly dispersed within the polyimide. And their particle size was relatively uniform, having a narrow distribution. Mostly nanosize Cu2O particles were formed in the specimen made from 10 nm thick Cu film and the mixture of nanosize particles and Cu layers were observed in the 30 nm thick Cu film. On the other hands, the Sn film undergoes surface reaction with the polyamic acid. Therefore, the synthesized SnO2 particles existed only at the surface of the substrate. SnO2 particle size distribution was not uniform in the polyimide. Although particles were not distributed uniformly in the polyimide, they were confined in a monolayer. The different particle distributions were attributed to the reactivity difference of PAA with Cu and Sn films.