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  • 1
    Publication Date: 2016-07-29
    Description: The metropolitan city of Seoul uses more energy than any other area in South Korea due to its high population density. It also has high emissions of air pollutants. Since an individual usually spends most of his/her working hours indoors, the ambient air quality refers to indoor air quality. In particular, PM10 concentration in the underground areas should be monitored to preserve the health of commuters in the subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation measure several air pollutants regularly. In this study, the accuracy of an instrument for PM measurement using the light scattering method was improved with the help of a linear regression analysis technique to continuously measure the concentrations in subway stations. In addition, an air quality monitoring system based on environmental sensors was implemented to display and record the data of PM10, CO2, temperature, and humidity. Through experimental studies, we found that ventilation fans could improve air quality and decrease PM10 concentrations in the tunnels effectively by increasing the air flow rate.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 2
    Publication Date: 2013-12-17
    Description: We fabricated solution-processed organic photovoltaic cells (OPVs) using substituted two sexithiophenes, a,w-bis(dimethyl-n-octylsilyl)sexithiophene (DSi-6T) and a,w-dihexylsexithiophene (DH-6T), as electron donors, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor. Solution-processed OPVs using DH-6T and DSi-6T showed good photovoltaic properties in spite of their poor solubility. The best performance was observed on DSi-6T : PCBM 1 : 5 (w/w) blend cell with an open circuit voltage () of 0.63 V, short circuit current density () of 1.34 mA/cm2, fill factor (FF) of 55%, and power conversion efficiency of 0.44% under AM 1.5 G illumination. Although DH-6T has higher hole mobility than DSi-6T, the DSi-6T : PCBM blend cell showed higher hole mobility than DH-6T : PCBM cell. Therefore, DSi-6T cell showed higher device performance than DH-6T cell due to its silyl substitutions, which lead to the increase of the solubility. The incorporation of solution-processed TiO2 interfacial layer in the DSi-6T : PCBM devices significantly enhances FF due to the reduced charge recombination near active layer/Al interface.
    Print ISSN: 1110-662X
    Electronic ISSN: 1687-529X
    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
    Published by Hindawi
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  • 3
    Publication Date: 2019-06-13
    Description: The purpose of this research was to analyze the quality and characteristics of four digital elevation models (DEMs) generated using in-track Korea Multi-Purpose Satellite (KOMPSAT)-3 stereo images. The sensor modeling methods were based on ground control points (GCPs), the initial rational polynomial coefficients (RPCs), relative adjustment, and the automatic bias-compensation method. The GCPs and check points (CPs) were extracted from the 0.25 m aerial orthoimage and the 5 m DEM provided by the National Geographic Information Institute (NGII). The DEMs had the same resolution as the reference DEM (5 m) and comparative analysis was carried out. The results indicate that when relative adjustment was applied alone (DEM 3), the percentage of matched points with a correlation of 0.8 or more was improved by at least 17% compared to the case where only initial RPCs were used (DEM 2). Although the absolute horizontal position error of DEM 3 could not be eliminated, the relative elevation error at the same position was reduced significantly. Therefore, if the relative positions of DEMs produced at different times can be corrected, they can be used for the detection of changes in altitude. When applying the automatic bias-compensation method (DEM 4) without GCPs, the percentage of matched points with a correlation of 0.8 or more was 70.1%. When GCPs were used (DEM 1), the value was 70.2%, i.e., almost identical to that of DEM 4. The mean difference in resolution among DEMs 1 and 4 was -1.8 ± 3.4 m (median, -1.0 m). The results show that DEMs of sufficient quality can be generated without GCPs. Furthermore, although discrepancies among the DEMs were noted in forest and shadow areas, it is possible to produce a 5~10 m resolution DEM by using additional image processing techniques, such as shadow removal.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 4
    Publication Date: 2013-01-01
    Description: We fabricated solution-processed organic photovoltaic cells (OPVs) using substituted two sexithiophenes, a,w-bis(dimethyl-n-octylsilyl)sexithiophene (DSi-6T) and a,w-dihexylsexithiophene (DH-6T), as electron donors, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor. Solution-processed OPVs usingDH-6TandDSi-6Tshowed good photovoltaic properties in spite of their poor solubility. The best performance was observed onDSi-6T : PCBM 1 : 5 (w/w) blend cell with an open circuit voltage (Voc) of 0.63 V, short circuit current density (Jsc) of 1.34 mA/cm2, fill factor (FF) of 55%, and power conversion efficiency of 0.44% under AM 1.5 G illumination. AlthoughDH-6Thas higher hole mobility thanDSi-6T, theDSi-6T : PCBM blend cell showed higher hole mobility thanDH-6T : PCBM cell. Therefore,DSi-6Tcell showed higher device performance thanDH-6Tcell due to its silyl substitutions, which lead to the increase of the solubility. The incorporation of solution-processed TiO2interfacial layer in theDSi-6T : PCBM devices significantly enhances FF due to the reduced charge recombination near active layer/Al interface.
    Print ISSN: 1110-662X
    Electronic ISSN: 1687-529X
    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
    Published by Hindawi
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