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We measured physical properties and optical properties of the black carbon (BC) generated in a spark discharger which did not produce soluble organic fractions. Effective densities and absorption cross-sections of the fresh BC were estimated using the electrical mobility diameter, the number concentration and the mass concentration. Size distribution measurements using a differential mobility analyzer (DMA) and a condensation particle counter (CPC) showed that the mode diameter and the number concentration increased with increasing spark frequency of the spark discharger. The primary particle size was also measured through the analysis of images observed using a field emission scanning electron microscope (FESEM), decreasing from 36.3 to 15.1 nm with increasing a spark frequency. The effective densities were estimated from 0.054 to 1.392 g/cm 3 and compared to be lower than those of atmospheric aerosols which might be aged. The absorption cross-sections were estimated as 1.0×10 –15 to 1.7×10 –15 m 2 depending on spark frequency. For the BC generated at a fixed constant spark frequency, the absorption cross-section was estimated to be larger as the BC became bigger in electrical mobility diameter. For the BC having the same electrical mobility diameter generated at different spark frequencies, however, the absorption cross-section generated at a faster spark frequency was smaller. Fractal dimension for the BC larger than 160 nm was measured to be 1.79, which is very similar to that for the spark-generated BC studied by other research group. In conclusion, the effective density allowed us to distinguish the core BC from aged BC.

I present a model in which (1) a more talent-demanding task increases both rewards for high talent and the penalty for low talent due to a greater fixed cost of production, and (2) individual talent is task-specific and talent updates occur only for tasks near the attempted task, which implies a task-sequence problem in which the initial task constrains subsequent task choices. Rising talent rewards and penalty stemming from a rising scale economy motivate young workers to choose a more talent-demanding task, raise the failure rate (i.e., the probability of the updated talent being lower than the exit threshold), and concentrate income gains in a diminishing fraction of high-talent workers. Rising talent rewards and penalty also increase the share of young workers subject to binding minimum current-income constraints, thus increasing the dispersion of tasks among young workers. The model sheds light on the rising stratification of careers among young workers and the rising polarization of the residual labor income distribution (i.e., the labor income distribution controlling for observable worker characteristics such as education and age).

Black carbon(BC) aerosols were monitored at the KIST site(37.603°N, 127.046°E) and Cheonan-KOREATECH site(36.766°N, 127.281°E) during the pre KORea-US Air Quality Study(KORUS-AQ) campaign using a couple of Muliti Angle Absorption Photometers(MAAP). BC mass concentrations were presented as 2.14μg/m± 3 1.06 and 0.94±0.60 μg/m 3 at KIST site(Seoul) and KOREATECH site(Cheonan), respectively. BC mass concentrations measured at KIST and KOREATECH sites from 22:00 on May 22 to 12:00 on May 23, 2015 showed 80% and 72% higher than average BC mass concentrations measured during campaign period, respectively. It indicates both sites could be influenced by a remote source. Similar patterns of BC concentrations between two sites from 20:00 to 24:00 on June 6, 2015 implies that the BC could be transported into both sites and then be stagnant inside the Korean Peninsula. Diurnal variation of BC in weekdays and weekends were also presented for the KIST and KOREATECH sites. Morning rush hour peak was observed at KIST site located in metropolitan area though no distinct morning rush hour peak was not observed at KOREATECH site located in a suburban area. This study revealed transport pathways of BC near the Korean Peninsula using back-trajectory analysis of BC measured both in a metropolitan area and in a suburban area.