Pedestrian-involved crashes that occurred in the city of San Francisco, California, over 6 years from 2002 to 2007 were analyzed to evaluate two key aspects of pedestrian safety: occurrence and severity. This analysis was done to identify locations with frequent occurrences of pedestrian-involved crashes and to examine various risk factors for the injury severity of pedestrian-involved crashes. A geographical information system analysis for hot spot identification showed that the frequency of pedestrian crashes was greater in the vicinity of the central business district but that the crash rate (the number of crashes per walking trip) was higher in the periphery of the city. For injury analysis, an ordered probit model was specified to evaluate risk factors that increased the probability of severe injury and fatality. Those factors were age (<15 and ≥65), alcohol consumption, and cell phone use among pedestrian characteristics; nighttime, weekends, and rainy weather among environmental characteristics; and, among crash characteristics, the influence of alcohol, larger vehicles (pickups, buses, and trucks), and vehicles proceeding straight and striking a pedestrian. The methods discussed are readily applicable to the evaluation of safety performance in other regions where pedestrian crash data are available.

From the perspective of the sustainability of aviation demand, we investigated passenger perceptions with regards to whether or not Korean people will resume the use of air transport after COVID-19. Based on five factors—the prevalence of COVID-19, requirements for self-isolation, circumstances at the destination, social atmosphere with regards to overseas travel, and level of preventative measures employed in the aviation service sector—a structured questionnaire was developed using confirmatory factor analysis. Based on these, the main levels of determination per factor were derived and a structured path for the recovery of aviation demand via structural equation analysis between factors was analyzed. The five factors established above were found to have a significant impact on passenger perceptions with regards to the restart of using air transport. It was found that people may consider resuming overseas travel with air transport, prior to the development of a COVID-19 cure or vaccine, corresponding to relaxed requirements for self-isolation if there is a fall in the number of confirmed cases. In addition, it was determined that the unconditional lifting of self-isolation requirements without considerations for the hygienic conditions of the destination has limitations in how much it will lead to the resumption of air travel. We hope that this study will serve as a starting point for other studies monitoring passenger behavior in the future and that it will lead to the development of sustainable strategies for recovering aviation demand.

In the present study, self-assembled hierarchical CoMn-LDH, CoMn@CuZnS, and CoMn@CuZnFeS heterostructured composites were synthesized for bifunctional applications. As an electrode for a supercapacitor, CoMn-LDH demonstrated superior areal and specific capacitance of 5.323 F cm⁻² (279.49 mAh/g) at 4 mA cm⁻², comparable to or even higher than other LDHs. The assembled AC//CoMn-LDH hybrid supercapacitor device further demonstrated better stability with 63% original capacitance over 20,000 cycles. Later, as a catalyst, CoMn-LDH, CoMn@CuZnS, and CoMn@CuZnFeS electrodes revealed better performance, with overpotentials of 340, 350, and 366 and −199, −215, and −222 mV to attain 10 mA cm⁻² of current density for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Moreover, for CoMn-LDH, small Tafel slopes of 102 and 128 mV/dec were noticed for OER and HER with good stability compared to heterostructured electrodes.

The purpose of this study is to develop the methodology to assess the sustainability of the aviation industry based on network data envelopment analysis (DEA) for the assessment of the national aviation industry process productivity. The national aviation industry is classified into the front stage, corresponding to the aviation market, and the behind stage, the ecosystem of the aviation industry from which added value is created. DEA for each stage and network DEA analysis from a system perspective and a process perspective were applied by integrating the two stages. Unlike the results of national productivity assessments based on previous aviation performance, it was found that the productivity varied among countries in each stage, and that the process of creating added value had the most profound effect on the overall sustainability determination of the national aviation industry. This methodology and the results are expected to contribute toward establishing the national policy direction for aviation industry sustainability.

We investigate whether air transport passengers changed their perceptions on the resumption of air transport use as the circumstances of the COVID-19 pandemic have changed. We surveyed 1200 Koreans, and then six months later re-surveyed 840 people among those who participated in the first survey. We built a structural equation model that was configured of five latent variables: COVID-19-related, self-isolation, destination condition, level of preventive measures in the airport/aircraft, and social perception. We performed paired sample t-test, multi-group analysis, and latent mean analysis for two divided groups, based on the survey period. We found that the perception structure on resuming air transportation use over time during the COVID-19 pandemic has not changed, though a significant change has occurred in the responses to the measured and latent variables. In particular, a high variation was found in the awareness of COVID-19-related factors and social perceptions, and we suggest continuous monitoring of the related factors to preemptively respond to the recovery of air transport demand. On the other hand, we propose proactive level setting and the maintaining of sanitary conditions of the destination and preventive measures in the airport/aircraft. We expect that this study will provide effective implications for the recovery of air transport demand during the COVID-19 pandemic.