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Preparing Korean EFL learners for English Communication with World Englishes and EIL
Joonwon Lee 아시아영어교육학회 2020 The Journal of Asia TEFL Vol.17 No.4
With the status as an international language, English is a language used by a variety of speakers in various situations (EIL). Therefore, to help students to be a competent English user is becoming more complex. For example, English learners are expected to communicate not only with native speakers of English, but also with English speakers whose native language is not English. However, Korean English education does not seem to be prepared to make Korean EFL learners competent English users. Thus, this paper deals with reasons why Korean English education is not reflecting EIL. This paper argues that the discrepancy between awareness of and attitude towards World Englishes is exposing Korean EFL learners only to native varieties of English, which probably causes difficulties in communicating in English. Along with the review on how Korean EFL stake holders consider English varieties other than native varieties, this paper proposes three feasible ways to incorporate different varieties of English with consideration of the local context of Korea.
Effects of a Near-Field Explosion in a Tunnel Behind a Blast Proof Door
Lee, Joonwon,Choi, Youngsik Korean Society for Precision Engineering 2018 International Journal of Precision Engineering and Vol.19 No.4
In this study, the propagation of a pressure wave inside a tunnel due to explosion near the blast proof door is investigated. In addition, the peak pressures and its arrival time are measured experimentally. Trinitrotoluene of 12 kg was detonated in front of a 20 mm thick steel blast proof door. Based on the experimental data, a finite element analysis was performed to analyze the pressure wave propagation phenomena inside the tunnel. The experimental measurements with four peak pressures match up well with the finite element analysis results. Additionally, the finite element analysis clearly showed pressure wave propagation sequence inside the tunnel. As it is difficult to explain the pressure wave propagation phenomena through experimental results, the finite element analysis can be useful for supporting the complex analysis.
Lee, Pyung-Gang,Lee, Sang-Hyuk,Kim, Joonwon,Kim, Eun-Jung,Choi, Kwon-Young,Kim, Byung-Gee Springer International 2018 Applied microbiology and biotechnology Vol.102 No.16
<P>A potent phytoestrogen, (S)-equol, is a promising isoflavone derivative drawing our great attention owing to its various biological and clinical benefits. Through selective activation of the estrogen receptor ER beta or androgen receptor, (S)-equol reduces menopausal symptoms, osteoporosis, skin aging, hair loss, and incidence of prostate or ovarian cancers without adverse effects. Traditional biosynthesis of (S)-equol exploited non-productive natural equol-producing anaerobic bacteria that mainly belong to Coriobacteriaceae isolated from human intestine. Recently, we developed a recombinant Escherichia coli strain which could convert daidzein into (S)-equol effectively under an aerobic condition. However, the yield was limited up to about the 200 mg/L level due to unknown reasons. In this study, we identified that the bottleneck of the limited production was the low solubility of isoflavone (i.e., 2.4 mg/L) in the reaction medium. In order to solve the solubility problem without harmful effect to the whole-cell catalyst, we applied commercial hydrophilic polymers (HPs) and a polar aprotic co-solvent in the reaction medium. Among the examined water-soluble polymers, polyvinylpyrrolidone (PVP)-40k was verified as the most promising supplement which increased daidzein solubility by 40 times and (S)-equol yield up to 1.22 g/L, the highest ever reported and the first g/L level biotransformation. Furthermore, PVP-40k was verified to significantly increase the solubilities of other water-insoluble natural polyphenols in aqueous solution. We suggest that addition of both HP and polar aprotic solvent in the reaction mixture is a powerful alternative to enhance production of polyphenolic chemicals rather than screening appropriate organic solvents for whole-cell catalysis of polyphenols.</P>
Lee, Pyung-Gang,Kim, Joonwon,Kim, Eun-Jung,Lee, Sang-Hyuk,Choi, Kwon-Young,Kazlauskas, Romas J.,Kim, Byung-Gee American Chemical Society 2017 ACS CHEMICAL BIOLOGY Vol.12 No.11
<P>Equols are isoflavandiols formed by reduction of soy isoflavones such as daidzein and genistein by gut microorganisms. These phytoestrogens are of interest for their various biological effects. We report biosynthesis from genistein to (−)-5-hydroxy-equol in recombinant <I>E. coli</I> expressing three reductases (daidzein reductase DZNR, dihidrodaidzein reductase DHDR, tetrahydrodaidzein reductase THDR) and a racemase (dihydrodaidzein racemase, DDRC) originating from the gut bacterium, <I>Slackia isoflavoniconvertens</I>. The biosynthesized 5-hydroxy-equol proved as an optically negative enantiomer, nonetheless it displayed an inverse circular dichroism spectrum to (<I>S</I>)-equol. Compartmentalized expression of DZNR and DDRC in one <I>E. coli</I> strain and DHDR and THDR in another increased the yield to 230 mg/L and the productivity to 38 mg/L/h. If the last reductase was missing, the intermediate spontaneously dehydrated to 5-hydroxy-dehydroequol in up to 99 mg/L yield. This novel isoflavene, previously not known to be synthesized in nature, was also detected in this biotransformation system. Although (<I>S</I>)-equol favors binding to human estrogen receptor (hER) β over hERα, (−)-5-hydroxy-equol showed the opposite preference. This study provides elucidation of the biosynthetic route of (−)-5-hydroxy-equol and measurement of its potent antagonistic character as a phytoestrogen for the first time.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/acbcct/2017/acbcct.2017.12.issue-11/acschembio.7b00624/production/images/medium/cb-2017-006244_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cb7b00624'>ACS Electronic Supporting Info</A></P>
A Parameter Study on Specimen Geometry for Concrete Dynamic Compression Test
Joonwon Lee,SeungPil Kim,JaeHoon Lim,Sang Soon Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
During normal and off-normal conditions, the concrete structures of dry storage system for spent nuclear fuel must maintain structural integrity. A stress-strain curve is the most important key factor for structural integrity evaluation. The ASTM C39 specifies the concrete specimen geometry for the static compression test. However, there is no standard specimen size for intermediate stain rate, and it is not easy to maintain consistency among all test results because the failure tendency is different from each other. In order to account for the strain rate effects on concrete, the dynamic increase factor (DIF) is conventionally addressed by dividing dynamic strength by static strength. However, the DIF value considers only the strength of concrete and does not describe the overall behavior of concrete, such as a stress-strain relation. The objective of this study is to propose proper specimen geometry for the concrete dynamic compression test by several parametric study. The static compression simulation results with the specimen specified in ASTM C39 showed the constant strain distribution in a cylindrical specimen. However, as the strain rate increases, the strain state in specimen showed a nonuniform with the same geometry of ASTM C39. The non-uniform strain state in the specimen deteriorates the consistency and accuracy of the compression test. Therefore, we presented the specimen shape and size to form a uniform strain state through radial direction by drilling a hole in the axial direction. We analyzed two specimens using ABAQUS with the concrete damaged plasticity model, one with a hole at the center and the other without the hole. As a result, the strain distribution became more uniform than the specimen without the hole. Based on the results, we proposed the specimen shape and size for the intermediate strain rate compression test.
Microfluidic-based cell handling devices for biochemical applications
Lee, Sanghyun,Kim, Hojin,Lee, Wonhyung,Kim, Joonwon IOP 2018 Journal of micromechanics and microengineering Vol.28 No.12
<P>Microfluidic-based cell handling techniques have become promising tools for biochemical applications, and many such techniques have been developed with the advancement of microfabrication technologies. A microfluidic-based platform used for biochemical analysis offers numerous benefits, including small sample consumption, massive parallelization, rapid analysis, and the capability for single-cell analysis, which are difficult to achieve in conventional cell handling methods on a large scale. It also exhibits precise spatial and temporal control of the local cellular microenvironments based on microfluidic networks in accordance to the unique fluidic phenomena of microfluidics. This review focuses on various cell handling methods that take advantage of microfluidics by classifying them in accordance to specific functions required for biochemical analyses, including (i) cell transfer, (ii) cell separation and sorting, (iii) cell immobilization, (iv) cell isolation and encapsulation, and (v) cell retrieval.</P>