• Korean small business review
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• v.43 no.1
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• pp.1-33
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• 2021

This study explores differential value implications of R&D expenditure across firms, especially in terms of growth potential of small businesses. Analyzing Korean listed firms for the period from 1982 to 2014, we document the followings. First, large firms, defined as the top quintile group based on market capitalization, have spent higher R&D expenditure compared to small (bottom quintile group) and medium (middle quintile groups) firms and the difference between groups has enlarged over time. Relatedly, the persistence of R&D spending, measured by the association between current R&D expenditure and cumulative future R&D expenditure over the next five years, is lowest in small firms. Second, R&D of large (small) firms are more (less) likely to generate operating profits over the next five years. Additional analyses suggest that the relation between R&D and gross margin is strongest in large firms, suggesting that R&D underlies their competitiveness in the product market. Third, small firms have borne the highest uncertainty related to R&D investment proxied by the association between current R&D and volatility of future earnings. As a result, the likelihood of R&D leading to future patents is also lowest in small firms. Fourth, the probability of moving up to the next size group within the next five years is significantly lower in small firms than others. Finally, we find that the divergence in R&D expenditure between large and small firms is positively associated with product market concentration. Overall, our findings confirm the small business growth trap in relation to R&D investment.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.2
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• pp.273-284
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• 2022

This study was conducted to examine the practical and educational implications of teachers' operation of the curriculum through science and online classes based on data collected for 4 months from 4 teachers who had experience in science subject online classes among homeroom teachers in the 3rd to 6th grades of elementary school in D city. This study was conducted through narrative inquiry. As a result of conducting interviews and in-depth interviews based on the online class experiences of the Earth Science Unit of the study subjects, and conducting field classes with related documents such as online class-related materials and teacher journals, teachers were more likely to take online classes compared to traditional face-to-face classes. They spent more time preparing and showed difficulties in the process of adapting to the new medium used in online classes. In addition, they demanded the provision of scientific materials produced in a pandemic situation and a teaching platform for smooth class operation. In particular, in the case of experimental classes, there is a burden of completing the planned curriculum, and in a pandemic situation, students felt the need for individual experimental tools for intensive science classes. As a result, it is necessary to introduce a blended learning learning system that combines the advantages of face-to-face and online classes as a new class form for the transition to future education in preparation for the pandemic. Continuous teacher research on the format and online class experience is required.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.304-313
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• 2016

One of the issues currently facing nuclear power plants is how to store spent nuclear waste materials which are contaminated with radionuclides such as $^{134}Cs$, $^{135}Cs$, and $^{137}Cs$. Bioremediation processes may offer a potent method of cleaning up radioactive cesium. However, there have only been limited reports on $Cs^+$ tolerant bacteria. In this study, we report the isolation and identification of $Cs^+$ tolerant bacteria in environmental soil and sediment. The resistant $Cs^+$ isolates were screened from enrichment cultures in R2A medium supplemented with 100 mM CsCl for 72 h, followed by microbial community analysis based on sequencing analysis from 16S rRNA gene clone libraries(NCBI's BlastN). The dominant Bacillus anthracis Roh-1 and B. cereus Roh-2 were successfully isolated from the cesium enrichment culture. Importantly, B. cereus Roh-2 is resistant to 30% more $Cs^+$ than is B. anthracis Roh-1 when treated with 50 mM CsCl. Growth experiments clearly demonstrated that the isolate had a higher tolerance to $Cs^+$. In addition, we investigated the adsorption of $0.2mg\;L^{-1}$ $Cs^+$ using B. anthracis Roh-1. The maximum $Cs^+$ biosorption capacity of B. anthracis Roh-1 was $2.01mg\;g^{-1}$ at pH 10. Thus, we show that $Cs^+$ tolerant bacterial isolates could be used for bioremediation of contaminated environments.