• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.185-192
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• 1998

Four kinds of polyamicacids(PAAs) were prepared by the condensation reaction of four diamines with different linkages, 3,3'-diaminodiphenyl sulfone(3,3'-$DDSO_2$), 4,4'-diaminodiphenyl sulfone(4,4'-$DDSO_2$), 4,4'-methylene dianiline(4,4'-MDA) and 4,4'-oxydianiline(4,4'-ODA), and dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA) using the solvent, dimethylacetamide(DMAc). These four PAAs were blended with poly[2,2-(m-phenylene)-5,5'-bibenzimidazole](PBI) from the solution blending. Then called as Blend-I, II, III, and IV, respectively. Cast films or precipitated powders of the PBI/PAA blends were cured at a higher temperature than expected Tg to transform into PBI/PIs blends. Miscibility, specific intermolecular interaction for miscibility and their relative strength as a function of polyimide chemical structure with different four diamines in the PBI/PI systems were investigated. Four blends used in this study were all miscible, and the specific intermolecular interactions existing in these blends was thought to be the hydrogen bonding between the N-H of PBI and the C=O of PIs. The hydrogen bonding in the blends were shown to be stronger in the Blend-III and Blend-IV than Blend-I and II. It is speculated that the differences of hydrogen bonding strength of PBI/PI blends are dependent upon chemical structures of PIs, that is, PIs consisting of $SO_2$ group have a weaker hydrogen bonding strength than those of O or $CH_2$ group because the former has a larger spacer than the latter.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1182-1190
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• 2007

The gene encoding for isoamylase of the Pectobacterium carotovorum subsp. carotovorum (Pcc) LY34 was cloned and expressed into Escherichia coli $DH5{\alpha}$. Isoamylase catalyzes the hydrolysis of ${\alpha}-1,6-glycosidic$ linkages specifically in amylopectin, glycogen, and derived oligosaccharides, while the enzyme did not hydrolyze ${\alpha}-1,4-glycosidic$ linkages of amylose. The isoamylase gene (glgX) had an open reading frame of 1,977 bp encoding 658 amino acid residues with a calculated molecular weight of 74,188 Da. The molecular weight of the enzyme was also estimated to be 74 kDa by activity staining of a SDS-PA gel. The mature GlgX had a calculated pI of 4.91. Isoamylase from Pcc LY34 had 70% amino acid identity with isoamylase from Pectobacterium chrysanthemi and contained the four regions conserved among all amylolytic enzymes. The isoamylase was optimally active at pH 7.0 and $40^{\circ}C$. GlgX was $Ca^{2+}-dependent$. The changes of Asp-335, Glu-370, and Asp-442 into Ala, respectively, using site-directed mutagenesis techniques showed that three residues are essential to isolamyalse (GlgX) activity. The sequences around those residues were highly conserved in isoamylase of different origins and GlgX of the glg operon in glycongen biosynthesis.

• Journal of The Korean Association of Information Education
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• v.21 no.6
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• pp.733-742
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• 2017

In recent years, There is a growing demand for more instructional hours because of the shortage of classes required for the software education included in the 2015 Revised Practical Arts Curriculum of elementary schools. Therefore, the Korea Association of Information Education developed the Informatics Curriculums Standard Model from 2014 to 2016 to revise the next 2020 curriculum. However, the KAIE curriculum lacks linkages with secondary school informatics curriculum and is not composed of core concept-based achievement criteria so that teachers have a lot of difficulties in reconstructing and operating the KAIE curriculum. In this study, four core concepts of information ethics were selected by conducting Delphi survey focusing on the teachers of elementary schools. In other words, we selected the core concepts of the information ethics domain: internet etiquette, personal information protection, information life, and copyright protection. Also, we suggested 16 specific criteria for the core concepts.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.251-258
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• 2018

The university bachelor's system is based on autonomy, but due to the rigid academic structure, it is not appropriate to respond to changes in social demand. Recently, universities are pursuing diversification of their bachelor's system. With the introduction of various majors (linkage major, convergence major, autonomic major, and self-design major), efforts are being made to nurture convergence talent based on mutual linkages between major and departments. This study introduces the design and operation process of 'Global Creative Convergence Major' which the four universities of Chungcheong region promoted as a union. In particular, it derives the key elements of each step and presents the operating model and implications based on the main features. Convergence major operation model constitutes educational system (talent award, educational goal, competency factor, curriculum) through linkage between specialization areas of universities. The competency elements contain creative competence, convergence competency, problem solving competency, and global competency.

• Mycobiology
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• v.47 no.2
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• pp.256-260
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• 2019

Neuraminidase (NA) cleaves the glycosidic bond linkages of sialic acids to release the mature virions from infected cells and has been an attractive therapeutic target for anti-influenza agents. In our ongoing investigation of NA inhibitors in mushroom extracts, we found that the extract the fruiting body of Glaziella splendens potently inhibited neuraminidase. The fruiting bodies of G. splendens were extracted and partitioned successively with hexane, ethyl acetate, and butanol. The ethyl acetate soluble-layer was subjected to silica gel and Sephadex LH-20 column chromatographies, and MPLC to obtain five compounds (1-5). Their structures were determined by spectroscopic methods. NA inhibitory activity of these compounds was evaluated using NAs from recombinant rvH1N1, H3N2, and H5N1 influenza A viruses. One compound (1) was elucidated as a new azaphilone derivative, and four compounds (2-5) were identified as entonaemin A, comazaphilone D, rubiginosin A, and entonaemin B, respectively. Compounds 3 and 4 showed considerable inhibitory activity against three types of neuraminidases with the $IC_{50}$ values of 30.9, 41.8, and $35.7{\mu}M$ for 3 and 46.5, 50.4, and $29.9{\mu}M$ for 4, respectively. This study reveals that the fruiting bodies of G. splendens possess azaphilone derivatives with the NA inhibitory activity. This is the first report on the isolation of neuraminidase inhibitors from the fruiting bodies of G. splendens.

• Journal of Family Relations
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• v.22 no.2
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• pp.119-145
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• 2017

Objectives: Grounded in a life-course perspective, this study examined the effects of non-coresident children's transitions to marriage and parenthood on the frequency of contact with their parents. Gender of adult children and the educational levels of both adult children and their parents were evaluated as potential moderators of the transition-contact linkages. Method: The analytic sample consisted of adult children aged between 20 and 50 whose parents participated in four waves of the Korean Longitudinal Study of Ageing (2006, 2008, 2010, 2012). For analysis, fixed effects regression models were estimated using the xtreg procedure in Stata. Results: First, transition to marriage was associated with a decrease in face-to-face contact, whereas a greater increase in contact with parents via phone, mail, email etc. occurred only among newly married with less than college education compared to the newlywed with college degrees. Second, transition to parenthood was associated with an increase in contact via phone, mail, email etc. In addition, a greater increase in face-to-face contact was found with parents who completed high school or more education compared to those with less than high school education. Conclusions: The findings suggest that adult children's transitions to marriage and parenthood may bring about increases in contact with their parents, particularly for adult children with less than college education and parents with more than high school education.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.855-866
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• 2021

The effects of various carbon sources on mycelial growth and polysaccharide synthesis of the medicinal fungus Inonotus obliquus in liquid fermentation were investigated. After 12-d fermentation, mycelial biomass, polysaccharide yield, and polysaccharide content were significantly higher in Glc+Lac group (glucose and lactose used as combined carbon source) than in other groups. Crude polysaccharides (CIOPs) and the derivative neutral polysaccharides (NIOPs) were obtained from mycelia fermented using Glc, fructose (Fru), Lac, or Glc+Lac as carbon source. Molecular weights of four NIOPs (termed as NIOPG, NIOPF, NIOPL, and NIOPGL) were respectively 780.90, 1105.00, 25.32, and 10.28 kDa. Monosaccharide composition analyses revealed that NIOPs were composed of Glc, Man, and Gal at different molar ratios. The NIOPs were classified as α-type heteropolysaccharides with 1→2, 1→3, 1→4, 1→6 linkages in differing proportions. In in vitro cell proliferation assays, viability of RAW264.7 macrophages was more strongly enhanced by NIOPL or NIOPGL than by NIOPG or NIOPF, and proliferation of HeLa or S180 tumor cells was more strongly inhibited by NIOPG or NIOPGL than by NIOPF or NIOPL, indicating that immune-enhancing and anti-tumor activities of NIOPs were substantially affected by carbon source. qRT-PCR analysis revealed that expression levels of phosphoglucose isomerase (PGI) and UDP-Glc 4-epimerase (UGE), two key genes involved in polysaccharide synthesis, varied depending on carbon source. Our findings, taken together, clearly demonstrate that carbon source plays an essential role in determining structure and activities of I. obliquus polysaccharides by regulating expression of key genes in polysaccharide biosynthetic pathway.

• Journal of Korean Academy of Rural Health Nursing
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• v.19 no.1
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• pp.55-65
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• 2024

Purpose: This study was intended to gain an in-depth understanding of and explored the experiences and meanings of participating in care services among community-dwelling older adults. Methods: A focus group interview approach was adopted. Twenty older adults were interviewed from November to December 2021 using semi-structured interview questions. The data was analyzed using thematic analysis. Results: Three main themes and seven sub-themes emerged for the elderly people living alone. One main theme was "ambivalence of elderly care services," the second was "desperate need for care services," and the third was "positive changes and expectations experienced with care services." For the elderly people living with their families, two main themes and four sub-themes were identified. One main theme was "care services met within the family system," the second was "needs for care services outside the family system." Conclusion: We aim to provide a basis for strengthening the quality of elderly community care services in the mid- to long-term and establish a system of close linkages between necessary services by understanding the needs of elderly people who live alone or with their families.

• Journal of Korean Library and Information Science Society
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• v.55 no.2
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• pp.243-266
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• 2024

In foreign countries, ISNI-based creative work identification and linkage services have been established and operated in various fields, while in Korea, ISNI utilization and linkage services limited to some fields are operated mainly by the National Library of Korea. The purpose of this study is to propose an ISNI-based linkage and utilization service that can be applied in Korea. To achieve the purpose of this study, we examined overseas ISNI linkage cases and identified the requirements of related organizations. We also proposed four ways to build ISNI sharing and convergence services. These include establishing Identifiers Co-operation Initiatives (ICI), establishing creator profiles, activating ISNI through the publishing industry, and activating ISNI services through external linkages. We hope that this study will serve as a basis for building ISNI-based linkage and utilization services.

• Journal of the Economic Geographical Society of Korea
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• v.1 no.1
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• pp.151-172
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• 1998

Over the past two decades, the process of globalization of multinational corporations has increased at a rapid rate. One manifestation of this process is the establishment of corporate head offices in a variety of international centers to administer and coordinate, the day-to-day operations in the host countries. In establishing a subsidiary overseas a firm creates a direct link between the operations of the domestic corporate center and the foreign host center This paper investigates elements of stability and change in the international linkage patterns among domestic parent corporations and host subsidiaries over the past several decades. In particular, it seeks answers to a number of question related to stability and change in linkages among foreign centers of control and those Canadian centers selected to administer the subsidiary operations from 1970 to 1991 over the four primary sectors, namely, resources, manufacturing, services, and finance. By confirming the core stability and dispersed linkages hypotheses, the papar offers some generalizations with respect to the location and stability of subsidiary headquarters centers in Canada and their respective subsector specialties. Finally, it addresses further research avenues fer the quaternary place study.