• The Plant Pathology Journal
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• v.29 no.2
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• pp.144-153
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• 2013

Diverse bacteria are known to colonize plants. However, only a small fraction of that diversity has been evaluated for their biopesticide potential. To date, the criteria for sampling and selection in such bioprospecting endeavors have not been systematically evaluated in terms of the relative amount of diversity they provide for analysis. The present study aimed to enhance the success of bioprospecting efforts by increasing the diversity while removing the genotypic redundancy often present in large collections of bacteria. We developed a multivariate sampling and marker-based selection strategy that significantly increase the diversity of bacteria recovered from plants. In doing so, we quantified the effects of varying sampling intensity, media composition, incubation conditions, plant species, and soil source on the diversity of recovered isolates. Subsequent sequencing and high-throughput phenotypic analyses of a small fraction of the collected isolates revealed that this approach led to the recovery of over a dozen rare and, to date, poorly characterized genera of plant-associated bacteria with significant biopesticide activities. Overall, the sampling and selection approach described led to an approximately 5-fold improvement in efficiency and the recovery of several novel strains of bacteria with significant biopesticide potential.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.781-786
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• 2000

An Er-doped sulfide fiber was drawn, and its spectroscopic properties were analyzed. Compositions of a 1000 ppmwt Er3+-doped core and an undoped clad were Ge30-Ga1-Asg-S61 and Ge30-As8-S62, in at.%, respectively. Refractive index of the core composition was approximately 0.01 high than that of the clad. In order to enhance the mechanical stability as well as to prevent infiltration of impurity ions such as OH-, an UV-curable polymer was used for the coating. The optical loss of a fiber formed directly from a polymer coated core rod without cladding was ∼15 dB/m at 1.06$\mu\textrm{m}$. In the case of a fiber with core/clad structure, the optical loss was so high that the stimulated emission of erbium fluorescence was not evident. It is believed that presence of inhomogeneous core/clad interface and crystalline aggregates precipitated in the clad region were responsible for the high optical loss. On the other hand, fluorescence characteristics of Er3+ embedded in the core region were more or loss deteriorate compared to fiber preform, which is attributed to the redistribution of the Er ions along with the partial crystallization of the core glass during the fiberization process.

• Bulletin of the Korean Chemical Society
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• v.22 no.5
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• pp.467-475
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• 2001

A triblock copolymer based on $poly(\varepsilon-caprolactone)$ (PCL) as the hydrophobic part and poly(ethylene glycol) (PEG) as the hydrophilic portion was synthesized by a ring-opening mechanism of ${\varepsilon}-caprolactone$ with PEG containing a hydroxyl group at bot h ends as an initiator. The synthesized block copolymers of PCL/PEG/PCL (CEC) were confirmed and characterized using various analysis equipment such as 1H NMR, DSC, FT-IR, and WAXD. Core-shell type nanoparticles of CEC triblock copolymers were prepared using a dialysis technique to estimate their potential as a colloidal drug carrier using a hydrophobic drug. From the results of particle size analysis and transmission electron microscopy, the particle size of CEC core-shell type nanoparticles was determined to be about 20-60 nm with a spherical shape. Since CEC block copolymer nanoparticles have a core-shell type micellar structure and small particle size similar to polymeric micelles, CEC block copolymer can self-associate at certain concentrations and the critical association concentration (CAC) was able to be determined by fluorescence probe techniques. The CAC values of the CEC block copolymers were dependent on the PCL block length. In addition, drug loading contents were dependent on the PCL block length: the larger the PCL block length, the higher the drug loading content. Drug release from CEC core-shell type nanoparticles showed an initial burst release for the first 12 hrs followed by pseudo-zero order release kinetics for 2 or 3 days. CEC-2 block copolymer core-shell type nanoparticles were degraded very slowly, suggesting that the drug release kinetics were governed by a diffusion mechanism rather than a degradation mechanism irrelevant to the CEC block copolymer composition.

• Journal of Adhesion and Interface
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• v.12 no.1
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• pp.16-25
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• 2011

Multi core-shell composite particles were prepared by the water-born emulsion polymerization of various core monomer such as methyl methacrylate (MMA), n-butyl methacrylate (BMA), and shell monomer such as MMA, BMA, stylene (St), 2-hydroxyl ethyl methacrylate (2-HEMA) and acrylic acid (AA) in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion, particle size and distribution, average molecular weight, molecular structure, glass transition temperature with DSC, morphology, tensile strength and elongation. In the case of the concentration of 0.02 wt% SDBS, the conversion of MMA core-(BMA/St/AA) shell composite particle was excellent as 98%. In the case of the concentration of 0.03 wt% SDBS, the particle size of BMA core-(MMA/St/AA) shell composite particle was high as $0.47{\mu}m$. We confirmed that 3 points of glass transition temperatures appear for multi core-shell composite particles compared to 2 points of glass transition temperatures appear for general core-shell composite particles. We showed that it is possible to adjust glass transition temperatures according to the kind and composition of the inner shell monomer that it is can be used as a adhesive binder material with improved adhesive power.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.10
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• pp.1610-1616
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• 2020

Objective: This study was to evaluate the effect of husbandry systems and strains on cecum microbial diversity of Jingyang chickens under the same dietary conditions. Methods: A total of 320 laying hens (body weight, 1.70±0.15 kg; 47 weeks old) were randomly allocated to one of the four treatments: i) Silver-feathered hens in enrichment cages (SEC) with an individual cage (70×60×75 cm), ii) Silver-feathered hens in free range (SFR) with the stocking density of 1.5 chickens per ten square meters, iii) Gold-feathered hens in enrichment cages (GEC), iv) Gold-feathered hens in free range (GFR). The experiment lasted 8 weeks and the cecum fecal samples were collected for 16S rDNA high throughput sequencing at the end of experiment. Results: i) The core microbiota was composed of Bacteroidetes (49% to 60%), Firmicutes (21% to 32%) and Proteobacteria (2% to 4%) at the phylum level. ii) The core bacteria were Bacteroides (26% to 31%), Rikenellaceae (9% to 16%), Parabacteroides (2% to 5%) and Lachnoclostridium (2% to 6%) at the genus level. iii) The indexes of operational taxonomic unit, Shannon, Simpson and observed species were all higher in SFR group than in SEC group while in GEC group than in GFR group, with SFR group showing the greatest diversity of cecum microorganisms among the four groups. iv) The clustering result was consistent with the strain classification, with a similar composition of cecum bacteria in the two strains of laying hens. Conclusion: The core microbiota were not altered by husbandry systems or strains. The free-range system increased the diversity of cecal microbes only for silver feathered hens. However, the cecum microbial composition was similar in two strain treatments under the same dietary conditions.

• Journal of the Korean Wood Science and Technology
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• v.13 no.4
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• pp.67-72
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• 1985

To improve the bending strength of sawdustboard, verious resin contents of 10, 13, 16, and 19% were applied to the thin shell (face layer) composed with wire net or not. The shell effect of sawdust and wire net composition formed with core sawdustboard were evaluated. Forcusing on the effects of wire net composition and noncomposition including a comparison with chipboard and veneer complyboard, bending properties (Modulus of rupture (MOR), Modulus of elasticity (MOE), Stress at proportional limit ($S_{pl}$). Work to maximum load ($W_{ml}$))were analyzed and discussed. 1. In modulus of rutpute, veneer comply was the highest (621.5 kg/$cm^2$), and next decreasing order was wire net composition (159.1 kg/$cm^2$), chipboard (81.75 kg/$cm^2$), and wire net noncomposition (76.21 kg/$cm^2$) as in modulus of elasticity, work to maximum load, except for stress at proportional limit. 2. The highly significant effects were shown in both wire net composition and noncomposition, at the same time wire net composition exceeded two times of noncomposition throughout resin contents in bending properties. Chipboard was similar to the mean or 16% resin content in noncomposirion. 3. Every board in wire net composition above 10% resin content was beyond 100 kg/$cm^2$ in MOR, minimum allowable strength for structural use according to KS F 3104. In conclusion, the feasibility for improving the bending strength of weak sawdustboard by wire net composed shell was offered.

• Journal of Ecology and Environment
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• v.44 no.2
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• pp.106-114
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• 2020

Background: Determining patterns of habitat use is key to understanding of animal ecology. Approximately 1% of bird species use brood parasitism for their breeding strategy, in which they exploit other species' (hosts) parental care by laying eggs in their nests. Brood parasitism may complicate the habitat requirement of brood parasites because they need habitats that support both their host and their own conditions for breeding. Brood parasitism, through changes in reproductive roles of sex or individual, may further diversify habitat use patterns among individuals. However, patterns of habitat use in avian brood parasites have rarely been characterized. In this study, we categorized the habitat preference of a population of brood parasitic lesser cuckoos (Cuculus poliocephalus) breeding on Jeju Island, Korea. By using compositional analyses together with radio-tracking and land cover data, we determined patterns of habitat use and their sexual and diurnal differences. Results: We found that the lesser cuckoo had a relatively large home range and its overall habitat composition (the second-order selection) was similar to those of the study area; open areas such as the field and grassland habitats accounted for 80% of the home range. Nonetheless, their habitat, comprised of 2.54 different habitats per hectare, could be characterized as a mosaic. We also found sexual differences in habitat composition and selection in the core-use area of home ranges (third-order selection). In particular, the forest habitat was preferentially utilized by females, while underutilized by males. However, there was no diurnal change in the pattern of habitat use. Both sexes preferred field habitats at the second-order selection. At the third-order selection, males preferred field habitats followed by grasslands and females preferred grasslands followed by forest habitats. Conclusions: We suggest that the field and grassland habitats represent the two most important areas for the lesser cuckoo on Jeju Island. Nevertheless, this study shows that habitat preference may differ between sexes, likely due to differences in sex roles, sex-based energy demands, and potential sexual conflict.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.720-729
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• 1996

An analysis of convective boiling heat transfer for refrigerant mixtures is performed for an annular flow to investigate the degradation of the heat transfer rate. Annular flow is selected in this study because a great portion of the evaporator in the refrigeration and air conditioning system is known to be in the annular flow regime. Mass transfer effect due to composition difference between liquid and vapor is included in this analysis, which is considered to be one of driving forces for the mass transfer at the interface. Due to the concentration gradient at the interface the mass transfer is interfered, so is the evaporative heat transfer at the interface. The mass transfer resistance makes the interface temperature slightly higher and, as a result, the heat transfer coefficients decrease compared with those without mass transfer effects. The degradatioin of the heat transfer rate reaches its maximum at a certain composition. The composition difference between vapor core and vapor at the interface has a direct effect on the temperature difference between the vapor core and the interface and the degradation of the heat transfer rate. Correction factor $C_{F}$ for the mixture effects is added to the correlation for pure substances and the flow boiling heat transfer coefficients can be calculated using the modified equation.n.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.644-651
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• 2003

Effects of additives on electrical properties and microstructure of MLCC X7R dielectrics have been investigated. The additives of glass frit or oxide form were added in the same main composition by the different powder processing conditions. As a result of the dielectric property and microstructure analysis, the composition having the glass layer with dopant concentration gradient showed the excellent dielectric properties. The MLCCs were fabricated with the excellent composition and all dielectric properties satisfied the X7R requirements.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.2
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• pp.115-128
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• 1998

Fisheries and merchant marine high school education is the core for human resources of fisheries and merchant marine industries. In the past, fisheries and merchant marine high school education was terminal education producing skilled worker in water area. But fisheries and merchant marine high school education are rater desired on educational role of helping student go on to college and to have continuing education after graduate high school. In this regard, the central purpose of this study was direction of basic composition on the 7th revised curriculum for the fisheries and merchant marine high school. The specific objectives were follow contents, this study present importance for 7th revised curriculum, and comparative analysis by the change of direction of basic composition from 1st revised curriculum to 7th revised curriculum. Also, this study present direction of basic composition on the curriculum in accordance with a change and demand of industrial society. The objective on the 7th revised curriculum for fisheries and merchant high schools is to teach students basic knowledge and skills related to fisheries and merchant marine industries, and self-reliant attitude so that students can get to the successful career roles in the rapidly changing industrial society.