• Journal of Adhesion and Interface
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• v.11 no.3
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• pp.112-119
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• 2010

Poly(methyl methacrylate)/poly(butyl acrylate) PMMA/PBA core-shell composite particles were prepared by the emulsion polymerization of MMA and BA in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion and particle size distribution, morphology, average molecular weight distribution, observation of film formation and particle formation, glass transition temperature and physical properties of polymerized core-shell composition particles for using adhesive binder. When the concentration of 0.03 wt% surfactant, the conversions of PMMA and PBA core polymerization are excellent as 95.8% for PMMA core and 92.3% for PBA core. Core-shell composite particles are obtained 90.0% for PMMA/PBA core-shell composite particles and 89.0% for PMMA/PBA core-shell composite particles. It is considered that the core and shell particles are polymerized to be confirmed FT-IR spectra and average molecular weight measured with a GPC, formation of the composite particles is confirmed by the film formation from normal temperature, and composition of inside and outside of the composite particle is confirmed by TEM photograph. The synthesized polymer has two glass transition temperatures, suggesting that the polymer is composed of core polymer and shell polymer unlike general copolymers. It is considered that each core-shell composite particle can be used as a high functionality adhesion binder by the measurement of tensile strength and elongation.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.678-684
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• 1998

By means of constant- pressure molecular dynamics simulations, we studied the liquid- glass- crystalline transition of a system composed of Lennard- Jones particles with periodic boundary conditions. Atomic volume and enthalpy were calculated as functions of temperature during heating and cooling processes. The Wendt- Abraham ratio derived from radial distribution function and the angular distribution function characterizing short range order were analyzed to distinguish between liquid, glass and crystalline states. A liquid phase resulting from a slow heating of an initial fee crystal amorphized on fast quench, but it crystallized on slow quench. When slowly heated, the amorphous phase from fast quench crystallized into an fee structure. A system with free surface was shown to melt from the surface inward at a lower temperature than bulk system and to have a strong tendency for crystallization even during a fast quench from a liquid state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.148-151
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• 2003

The spin density of ${\beta}-MnO_2$ structure was theoretically investigated by $DV-X_{\alpha}$ (the discrete variation $X{\alpha}$) method, which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The used cluster model was $[Mn_{14}O_{56}]^{-52}$. The ${\beta}-MnO_2$ is a paramagnetic oxide semiconductor material having the energy band gap of 0.18 eV and an 3 loan-pair electrons in the 3d orbital of an cation. This material exhibits spin-only magnetism and has the magnetic ordering temperature of 94 K. Below this temperature its magnetism appears as antiferromagnetism. The calculations of electronic state showed that if the initial spin condition of input parameters changed, the magnetic state changed from paramagnetic to antiferromagnetic. When d orbital of all Mn atoms in cluster had same initial spin state as only up spin, paramagnetic spin density distribution appeared by the calculation. On the other way, d orbital had alternately changed spin state along special direction the resulted spin distribution showed antiferromagnetism.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.482-489
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• 2007

Fluorescence properties and carbohydrate content were investigated using ultrafiltrated size fractions of dissolved organic matters (DOM) originated from different sources. The materials included a treated sewage, an algal organic matter, and a soil leachate, all of which are major constituents of dissolved organic matter in a typical urban river. Four different size fractions were separated from the three sources of each DOM. The size distribution demonstrated that a higher molecular weight fraction was more present in soil leachate compared to two other source DOMs. A higher content of carbohydrates was observed in the following order - algal DOM > treated sewage > soil leachate. A wide range of specific UV absorbance was observed from size fractions of a single source DOM, indicating that aromatic carbon structures are heterogeneously distributed within one source of DOM. The structural heterogeneity was the most pronounced for the soil leachate. The fluorescence index ($F_{450}/F_{500}$) of the treated sewage was similar to that (2.0) typically obtained from autochthonous DOM, suggesting that the treated sewage exhibited autochthonous organic matter-like properties. No protein-like fluorescence intensities were observed for all of the soil leachate size fractions whereas they were observed with two other source DOMs. Based upon the fluorescence peak ratios from fluorescence excitation-emission matrix (EEM), two discrimination indices could be suggested to distinguish three different source DOMs. It is expected that the suggested discrimination indices will be useful to predict the sources of DOM in a typical urban river affected by treated sewage.

• Polymer(Korea)
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• v.35 no.6
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• pp.531-536
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• 2011

Homopolymer distribution in block copolymer/homopolymer blends was investigated as a function of homopolymer concentration and homopolymer molecular weight. The deuterated poly(methyl methacrylate) or polystyrene was blended with a deuterated polystyrene-poly(methyl methacrylate) diblock copolymer up to a concentration of 20 wt%. Samples were characterized by small-angle X-ray scattering (SAXS), neutron reflectivity and transmission electron microscopy. The block copolymer with a thin-film geometry formed alternating lamellar microdomains oriented parallel to the substrate surface. By adding the homopolymer, the microdomain structure was significantly disturbed. As a consequence, a poorly ordered morphology appeared when the homopolymer concentration exceeded 15 wt%. Increasing the homopolymer concentration and/or the homopolymer molecular weight caused the microdomains to swell less uniformly, resulting in segregation of the homopolymer toward the middle of the microdomains.

• Korean Journal of Food Science and Technology
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• v.53 no.5
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• pp.514-520
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• 2021

This study identified and quantified the sugar-related metabolites and analyzed the structural features of starch in kimchi added with various concentrations of glutinous rice paste during fermentation. The pH values and total bacterial counts indicated that the fermentation of kimchi with 10% glutinous rice paste progressed more quickly than that of kimchi with other rice paste concentrations. The addition of glutinous rice pastes to kimchi resulted in increased glucose and decreased fructose contents during fermentation compared to the control kimchi. Maltose content increased significantly with increasing glutinous rice paste concentrations. The average chain length distribution of starch in kimchi decreased with increasing proportions of short chains as fermentation progressed. However, the average chain length distribution of starch increased with increasing glutinous rice paste concentration in kimchi. Our results confirmed that the sugar-related metabolites and starch structural changes were highly influenced by the added starch paste concentration.

• Parasites, Hosts and Diseases
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• v.56 no.6
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• pp.559-565
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• 2018

The identification and characterization of pathogenic and zoonotic tick-borne diseases like granulocytic anaplasmosis are essential for developing effective control programs. The differential diagnosis of pathogenic Anaplasma phagocytophilum and non-pathogenic A. phagocytophilum-like Anaplasma spp. is important for implementing effective treatment from control programs. The objective of the present study was to investigate the prevalence of Anaplasma spp. in horses in Korea by nucleotide sequencing and restriction enzyme fragment length polymorphism assay. Of the 627 horses included in the study, only 1 (0.2%) was infected with A. phagocytophilum. Co-infection with A. phagocytophilumlike Anaplasma spp. was not detected in the study. The 16S rRNA sequence of A. phagocytophilum was similar (99.5-100%) to A. phagocytophilum 16S rRNA isolated from horses in other countries. PCR adapted to amplify A. phagocytophilum groEL and msp2 genes failed to generate amplicons, suggesting genetic diversity in these genes. This study is the first molecular detection of A. phagocytophilum in horses in Korea. Human granulocytic anaplasmosis and animal infection of A. phagocytophilum have been reported in Korea recently. Because of vector tick distribution, global warming, and the increase of the horse industry, horses should be considered as a potential reservoir for A. phagocytophilum, and cross infectivity should be evaluated even though a low prevalence of infection was detected in this study. Furthermore, continuous surveillance and effective control measures for A. phagocytophilum should be established to prevent disease distribution and possible transmission to humans.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1013-1022
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• 2023

Arbuscular mycorrhizal fungi (AMF) are widespread soil endophytic fungi, forming mutualistic relationships with the vast majority of land plants. Biochar (BC) has been reported to improve soil fertility and promote plant growth. However, limited studies are available concerning the combined effects of AMF and BC on soil community structure and plant growth. In this work, a pot experiment was designed to investigate the effects of AMF and BC on the rhizosphere microbial community of Allium fistulosum L. Using Illumina high-throughput sequencing, we showed that inoculation of AMF and BC had a significant impact on soil microbial community composition, diversity, and versatility. Increases were observed in both plant growth (the plant height by 8.6%, shoot fresh weight by 12.1%) and root morphological traits (average diameter by 20.5%). The phylogenetic tree also showed differences in the fungal community composition in A. fistulosum. In addition, Linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed that 16 biomarkers were detected in the control (CK) and AMF treatment, while only 3 were detected in the AMF + BC treatment. Molecular ecological network analysis showed that the AMF + BC treatment group had a more complex network of fungal communities, as evidenced by higher average connectivity. The functional composition spectrum showed significant differences in the functional distribution of soil microbial communities among different fungal genera. The structural equation model (SEM) confirmed that AMF could improve the microbial multifunctionality by regulating the rhizosphere fungal diversity and soil properties. Our findings provide new information on the effects of AMF and biochar on plants and soil microbial communities.

• The Korean Journal of Food And Nutrition
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• v.37 no.1
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• pp.17-29
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• 2024

To increase industrial applicability of Astragalus membranaceus (AM) as immunostimulating materials, hot-water extract (AME) was prepared from AM and fermented with Kimchi-lactic acid bacteria (Lactobacillus sakei & Leuconostoc mesenteroides) to prepare fermented AM-postbiotics (FAME). Although FAME prepared from AM-postbiotics did not show a significant enhancement in macrophage stimulating activity compared to non-fermented AME, crude polysaccharide (FAME-CP) fractionated by EtOH precipitation from FAME showed significantly higher macrophage stimulating activity than AME-CP. Compared to AME-CP, FAME-CP showed dramatic changes in component sugar and molecular weight distribution. FAME-CP was a polysaccharide with a major molecular weight distribution of 113.4 kDa containing Man (44.2%), Glc (19.3%), Gal (10.2%), GalA (10.2%), and Ara (7.4%) as sugar components. FAME-CP with enhanced macrophage stimulatory activity not only increased expression levels of mRNA genes encoding macrophage-activated factors (iNOS, TNF-α, MCP-1, IL-6, and COX-2), but also led the nuclear translocation of activated p65 and c-Jun. In conclusion, crude polysaccharide from AM-postbiotics fermented with lactic acid bacteria could increase industrial applicability as a functional material with enhanced immunostimulating activity than AME-CP.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.4
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• pp.87-98
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• 2015

The natural monument forests (no.374) located at Pyeongdae-ri in Jeju island are described and classified by using phytosociological methods and numerical analysis. The purpose of this paper is to identify the ecological character of Torreya nucifera forests between natural habitat and artificial habitat, as well as their spatial and phytogeographical distribution in the Korea. The comparison of forests between Pyeongdae-ri and other regions was analyzed by using a non-metric multidimensional scaling analysis (NMDS) and hierarchical clustering. On the basis of the 12 phytosociological $relev{\acute{e}}s$, the vegetation of T. nucifera dominant forest in Jeju island was arranged in one syntaxon (Alangium platanifolium-Torreya nucifera community included typicum and one subcommunity) within Camellietea. The community of T. nucifera dominant forests were characterized floristically and ecologically. We discussed diagnostic species with references, and proposed a few important diagnostic species (Ilex crenata for. microphylla, Acer palmatum, Zingiber mioga, Mercurialis leiocarpa, Osmorhiza aristata, Mecodium wrightii etc.) to explain condition of the habitat and synecological character. The communities were described by concerning their edaphical and syndynamical niche; we discussed their total distribution in Korea. In most forests they are widespread in Korean peninsular and their distribution is primarily determined by artificial plantation and periodical management. The forests consisted of T. nucifera have developed from natural environment element and artificial management. As a result they have very unique characters with the floristic, structural characterization and distribution. Furthermore, we identified that they need to apposite management for sustainability.