PURPOSES : This study aimed to explore crowding impedance for high-risk travelers on various modes of public transit during the COVID-19 pandemic and develop a transport policy to encourage the proper use of public transport. METHODS : A stated preference survey was conducted to investigate the behaviors of travelers on various modes of public transit, with special emphasis on crowding inside vehicles. Multinomial logit-based modeling was used to estimate the explanatory variables identified as parameters based on the surveyed data. A crowding multiplier was adopted to represent the behavioral differences for the high-risk travelers on various modes of public transit. RESULTS : The established model was solved using the ‘mlogit’ R package program to estimate the identified parameters. The results demonstrated significant behavioral difference for the high-risk travelers on public transit during the COVID-19 pandemic. The proposed crowding multiplier successfully captured the reduced likelihood of high-risk travelers to be sensitive to crowding on the subway; furthermore, it revealed that non-crowding travelers on the subway are less sensitive to crowding than bus travelers. CONCLUSIONS : This study estimated crowding impedance for high-risk travelers on various modes of public transit during the COVID-19 pandemic and suggested an appropriate transport policy for those travelers.

One disadvantage of deep cycle flooded lead-acid batteries is increasing water loss caused by use of (+) Pb-Sb / () Pb-Sb alloy grid. Water loss is generated by the emission of hydrogen gas from the () electrode during battery charging. In this paper, we maintain cycle life aspect through the development of hybrid flooded lead-acid batteries to which a (+) Pb- Sb / () Pb-Ca grid is applied and deal with the improvement of water loss. The amount of water loss compared to that of the () Pb-Sb grid decreased when Ca was added to the () Pb grid. For the () Pb-Ca grid, it was confirmed that the time to reach 0.0 V, at which water decomposition occurs, was increased compared to that of the () Pb-Sb grid at the NPV (Negative Potential Voltage). In the cycle life test conducted with the BCI (Battery Council International) standard, compared to the (+) Pb-Ca grid, the (+) Pb-Sb grid increased the life cycle of the batteries and the (+) Pb-Ca grid showed an early end of life due to PbO corrosion layer generation, as determined through SEM / EDS and Tear Down analysis. In conclusion, by addition of Sb to (+) Pb grid and Ca to () Pb grid, we developed a hybrid flooded lead-acid battery that meets user requirements to improve water loss characteristics and preserve cycle life characteristics.

본 연구의 목적은 EMS를 장착한 손목 보호대를 이용해 실제 루어낚시참여자의 손목 통증 저하와 손목 기능개선 에 미치는 영향을 알아보는 것이다. 본 연구는 장시간 손으로 낚싯대를 들고 있어야 하는 루어낚시에서 사용가능한 손목 보호대 두 가지 제품을 선별해 전도성 원단을 결합했다. 건강한 35세에서 45세 남성 10명을 대상으로 진행하였 고, 선정 조건은 손목부위에 수술 이력이 없고 현재 취미로 루어낚시를 즐기고 있는 사람을 대상으로 선별하였다. 실험동작은 악력과 손목관절 굽힘의 측정(Range of Motion ROM)의 동작으로, 루어낚시를 했을 때의 손목피로도 유발을 위해 지연성 근육통을 유발하는 캐스팅 100회씩을 각 실험 전에 실시하였다. 본 연구의 결과 손목을 감싸는 형태와 반장갑형태의 손목밴드를 착용 후 전기 자극을 주었을 때 통증저하와 ROM 및 악력 기능이 향상되었음을 알 수 있었다. 본 연구의 결론으로 손목보호대에 전기 자극을 적용하였을 때 손목의 피로도와 기능 개선에 효과가 있음을 확인할 수 있었다. 본 연구를 통해 EMS를 장착한 손목 보호대 착용이 루어낚시 참여자들로 하여금 손목 부상을 예방하고 기능회복 증진에 유의미한 효과가 있음을 기대할수 있다.

To assess the influence of environmental factors on the phytoplankton community structure and total phytoplankton biomass during four seasons in 2014, we investigated the abiotic and biotic factors at 25 stations in the Busan coastal region. The phytoplankton community and total phytoplankton biomass were strongly dependent on the discharge from the Nakdong River, and the high density of phytoplankton was related with the introduction of the Tsushima Warm Current (TWC), particularly in the thermohaline fronts of the fall season. The relationship between the salinity and nutrient (Dissolved inorganic nitrogen=DIN: R 2=0.72, p<0.001 and Dissolved inorganic silicon=DSi: R 2=0.78, p<0.001) highly correlated with the river discharge, implying that those nutrients have played a crucial role in the growth of diatom and cryptophyta. The total phytoplankton biomass was highest in the summer followed by autumn, spring, and winter. Diatom and cryptophyta species were dominant species during the four seasons. Additionally, there were strong positive correlations between Chlorophyll a and total phytoplankton biomass (R 2=0.84, p<0.001), cryptophyta (R 2=0.76, p<0.001) and diatom (R 2=0.50, p<0.001), respectively. In particular, we found that there were significant differences in the nutrients, phytoplankton community compositions, and total phytoplankton biomass between the inner and the outer coastal region of Busan, depending on the amount of river discharge from the Nakdong River, particularly during rainy seasons. Therefore, the seasonal change of TWC and river discharge from the Nakdong River serve an important role in determining phytoplankton population dynamics in the Busan coastal region.

We attempted to estimate potential habitats of Clithon retropictus and to determine the community structure of benthic macroinvertebrates by presence of C. retropictus. 2016 to 2018 database of “Survey and Assessment of Estuary Ecosystem Health” by the Ministry of Environment were used to identify the distribution site of C. retropictus. The occupancy model was applied to estimate the potential habitat of C. retropictus. Four diversity indices were used to confirm the community structure of benthic macroinvertebrates. C. retropictus was found in the southern coast area and part of the east coast, and this pattern was consistent with previous studies. Additionally, the occupancy model predicted that a potential habitat of C. retropictus could appear in the west coast area. The community structure of benthic macroinvertebrates was relatively high at the site with C. retropictus than the site without C. retropictus. Therefore, the occupancy model can be considered when conserving C. retropictus inhabiting a limited area. Additionally, C. retropictus can be used to the indicator species that can represent the brackish water environment.

A survey was conducted to analyze seasonal dynamics of the phytoplankton community at 22 stations on the surface and bottom layers in the Anma Islands of Yeonggwang (AIY) in the southern West Sea, Korea from the spring of 2020 to the winter of 2021, using a marine survey vessel Ed Ocean. Based on the survey results, there were 87 phytoplankton species in 52 genera, diatoms accounted for 67.8%, dinoflagellates 26.5%, silicoflagellates 3.5%, and cryptomonads and euglenoids accounted for 1.1% each. By season, it was simple in spring and relatively varied in winter. The phytoplankton standing crop on the surface was low (28.8±30.1 cells mL-1) in summer and high (87.0±65.1 cells mL-1) in spring. In the phytoplankton community, diatoms showed a high share (over 80%) throughout the year, and Skeletonema costatum-ls was the dominant species with a dominance of more than 60% in spring and winter, and 34.6% and 24.2% in summer and autumn, respectively. The diversity expressing the characteristics of the community structure was high (2.79±0.45) in autumn and low (1.82±0.18) in spring, unlike the phytoplankton standing crop. However, the dominance was high at (0.86±0.08) in spring and low (0.44±0.13) in autumn. Based on the results of principal component analysis (PCA) using environmental and phytoplankton-related factors, it was estimated that the biological oceanographic environmental characteristics seen through the phytoplankton community in the AIY were dominated by nutrients supplied from open seawater and surface sediments by seawater mixing, such as tidal mixing.