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Yubin JEON,Haeng-Geun CHA,Youjung KONG,Hyeji JIN,Byeonguk LEE,See-Hyoung PARK,Kyungmoon PARK 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
As the consumption of plastics in the world causing lots of environmental problems increases, the interest in plastic degradation have been greater than before. Among the biodegradable plastics, PBAT and PBS are the most popular bioplastics. We tested 20 of halophilic bacteria, 4 Bacillus pumilus, and 4 PHB degrading bacteria from Konkuk university to select the strains that can effectively degrade PBAT and PBS. Bacillus pumilus 3348, Bacillus pumilus 3713, Bacillus pumilus 3855, and Bacillus pumilus 13101 showed the potential of PBAT and PBS degradation through the halo formation on PBAT and PBS emulsified plates. In order to confirm that lipase would degrade PBAT and PBS, one of lipase products, CALB, was used to observe lipase activity to degrade PBAT and PBS. In conclusion, we found that Bacillus pumillus reported to have lipase genes in NCBI can degrade PBAT and PBS.
Exploring the Efficacy of Automated Essay Scoring Systems in the Context of Korean EFL High School
Yubin Jeon 한국영어평가학회 2023 영어평가 Vol.18 No.1
Despite growing attention on the Automated Essay Scoring (AES) systems, it is difficult to find their actual use in Korean EFL high schools. Among various free and easily accessible AES systems available, this study aims to investigate the efficacy of three AES systems in the Korean EFL high school context: Grammarly, MS Editor, and ProWritingAid. To this end, the three AES systems were compared with two human raters in three aspects: scores reported on Korean EFL high school students’ writings, errors detected per error category, and errors detected per student writing. The t-test, ANOVA, and correlation analysis results have led to questions and doubts on the validity of the AES programs and their role as essay evaluators. While AES programs have shown growth, the AES programs are not yet comparable to human raters and teacher feedback. However, the AES programs do show potential as a supplementary tool in the Korean EFL context. Thus, a comparison of the three AES systems was examined in the hopes of finding the optimal choice of AES system. The findings provide information and insights on how AES systems may be implemented in Korean EFL high school classrooms, and further emphasized the importance of teachers’ role in implementing a new tool.
Jeon Yubin,Jin HyeJi,Kong Youjung,Cha Haeng-Geun,Lee Byung Wook,Yu Kyungjae,Yi Byongson,Kim Hee-Taek,Joo Jeong Chan,Yang Yung-Hun,Lee Jongbok,Jung Sang-Kyu,Park See-Hyoung,Park Kyungmoon 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.8
Poly(3-hydroxybutyrate) (PHB) is a biodegradable and biocompatible bioplastic. Effective PHB degradation in nutrient-poor environments is required for industrial and practical applications of PHB. To screen for PHB-degrading strains, PHB double-layer plates were prepared and three new Bacillus infantis species with PHB-degrading ability were isolated from the soil. In addition, phaZ and bdhA of all isolated B. infantis were confirmed using a Bacillus sp. universal primer set and established polymerase chain reaction conditions. To evaluate the effective PHB degradation ability under nutrient-deficient conditions, PHB film degradation was performed in mineral medium, resulting in a PHB degradation rate of 98.71% for B. infantis PD3, which was confirmed in 5 d. Physical changes in the degraded PHB films were analyzed. The decrease in molecular weight due to biodegradation was confirmed using gel permeation chromatography and surface erosion of the PHB film was observed using scanning electron microscopy. To the best of our knowledge, this is the first study on B. infantis showing its excellent PHB degradation ability and is expected to contribute to PHB commercialization and industrial composting.
Jeon, Dongho,Jun, Yubin,Jeong, Yeonung,Oh, Jae Eun Elsevier 2015 Cement and concrete research Vol.67 No.-
<P><B>Abstract</B></P> <P>This study explores the beneficial effects of Na<SUB>2</SUB>CO<SUB>3</SUB> as an additive for microstructural and strength improvements in a Ca(OH)<SUB>2</SUB>-activated fly ash system. NaOH-activated fly ash samples were also tested to compare the effect of Na<SUB>2</SUB>CO<SUB>3</SUB>. Compressive strength testing, XRD, SEM/BSE/EDS, <SUP>29</SUP>Si/<SUP>27</SUP>Al MAS-NMR, MIP and TGA were performed. The testing results indicate that the use of Na<SUB>2</SUB>CO<SUB>3</SUB> for Ca(OH)<SUB>2</SUB>-activation led to a noticeable improvement in strength and microstructure, primarily due to (1) more dissolution of raw fly ash at an early age, (2) more formation of C–S–H [or C–S–H(I)], (3) porosity reduction, and (4) pore-size refinement. We also found that (1) an early high alkalinity from the NaOH formation was not a major cause of strength, (2) geopolymer was not formed despite the early NaOH formation, and (3) no visible pore-filling action of CaCO<SUB>3</SUB> was observed. However, Na<SUB>2</SUB>CO<SUB>3</SUB> did not produce any improvement in strength for NaOH-activated fly ash.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of Na<SUB>2</SUB>CO<SUB>3</SUB> significantly improved strength and microstructure. </LI> <LI> The use of Na<SUB>2</SUB>CO<SUB>3</SUB> induced more dissolution of raw fly ash at early ages. </LI> <LI> The use of Na<SUB>2</SUB>CO<SUB>3</SUB> promoted more C–S–H [or C–S–H(I)] formation. </LI> <LI> The use of Na<SUB>2</SUB>CO<SUB>3</SUB> reduced total porosity and refined pore-size distribution. </LI> <LI> The use of Na<SUB>2</SUB>CO<SUB>3</SUB> produced neither geopolymer formations nor pore-filling actions from CaCO<SUB>3</SUB>. </LI> </UL> </P>