• Journal of the Korean School Mathematics Society
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• v.11 no.3
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• pp.439-466
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• 2008

In this paper, we aim to draw up an alternative instruction scheme by designing a web based instruction model on mathematics. Some learning materials are developed according to the scheme, and its educational effects are examined when it is committed to through regular curriculum. The study is composed of three major parts; setting of the theoretical foundation on cultivating Web based educational materials, design and composition of Web based teaching-learning model, and its experiments in the regular class. First of all, we are concerned with the core principles on WBI including the learning theories, developing learner oriented instruction model, design as well as build-up process for education materials, and strategy in instruction. Next, we propose an alternative instruction model for mathematics, in which programs to embody mathematics education and instruction on the Web are constructed, on the while, the study is proceeded through the Web Site. Finally, we design and produce a WBI instruction model on the subject of the plane quadratic curves. This model is examined in the regular class to estimate its educational effects compared with traditional teaching standpoints. Concomitantly, we explore essential elements and the direction of future growth associated with the Web oriented education.

• Journal of the Korean Wood Science and Technology
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• v.23 no.2
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• pp.55-69
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• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• Journal of the Mineralogical Society of Korea
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• v.24 no.2
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• pp.133-143
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• 2011

In Mujoo area, the granitic pegmatites are developed in the granitic gneiss complex with Jurassic gneissic granites, where Nb-Ta mineralization were reported. Pegmatites are mainly composed of large crystals of quartz, feldspars of end-member orthoclase and albite, and muscovite. Nb-Ta minerals in study area are columbite (Nb > Ta) in composition. Chemistry of muscovites shows post-magmatic in origin and they are closely related with columbite. Large columbite, in pegmatites occurred with quartz and feldspars, while microcrystalline columbite is associated with muscovite. The Nb contents in large columbite are relatively higher than those in microcrystalline ones. Two pegmatites, 4~15 m in width and 120 m, 250 m in extension respective1y, are developed. Five drilling cores with total 600 m in length are finally obtained and revealed no possible potential for economic rare metals of Na-Ta deposits.

• Journal of Powder Materials
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• v.22 no.6
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• pp.426-431
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• 2015

Microstructural examination of the Nb-Si-B alloys at Nb-rich compositions is performed. The Nb-rich corner of the Nb-Si-B system is favorable in that the constituent phases are Nb (ductile and tough phase with high melting temperature) and $T_2$ phase (very hard intermetallic compound with favorable oxidation resistance) which are good combination for high temperature structural materials. The samples containing compositions near Nb-rich corner of the Nb-Si-B ternary system are prepared by spark plasma sintering (SPS) process using $T_2$ and Nb powders. $T_2$ bulk phase is made in arc furnace by melting the Nb slug and the Si-B powder compact. The $T_2$ bulk phase was subsequently ball-milled to powders. SPS is performed at $1300^{\circ}C$ and $1400^{\circ}C$, depending on the composition, under 30 MPa for 600s, to produce disc-shaped specimen with 15 mm in diameter and 3 mm high. Hardness tests (Rockwell A-scale and micro Vickers) are carried out to estimate the mechanical property.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.5
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• pp.37-51
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• 2011

Research and conservation of plant species for the nation arboretum, collection and securing of the plant species for both public and private arboreta and education for the arboreta which is affiliated to the university are overall management goal of the arboreta in Korea. Most of the arboreta in Korea run the programs and events for guide and interpretation of forest, but the programs and events are not well specified by the arboreta. Regarding the reasonable level of entrance fee should be discussed further as the lack of information and understanding. But the specified entrance fee between public and private arboreta should be considered. An eighty three percent of arboreta in Korea has been properly managed the species information. The reasonable management should be considered in case of unusual management of collected plant genetic resources. Although the overall impending difficulties for the management of arboreta in Korea is the lack of trained or qualified staffs, securing tasks independently for the public arboreta and relatively low salary for the private arboreta are main difficulties. Most of the difficulties are derived from the lack of its mission of the arboreta. The management of arboreta by the mission statement is one of the core targets including the characters such as climate or region should be considered. The securing qualified or trained staffs should be considered in the development of arboreta in Korea including the modification of relevant regulations or law.

• Journal of Internet Computing and Services
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• v.20 no.6
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• pp.167-177
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• 2019

The enhancement of national competitiveness in future society is the discovery and training of excellent SW convergence gifted. In order to cultivate these SW convergence gifted, reinforcing competence of teachers in charge should be made first. Therefore, in this paper, artificial intelligence education contents, one of the core technologies of the 4th Industrial Revolution era, were developed to reinforcing competence of SW convergence gifted teachers. After setting the direction of artificial intelligence education content, we constructed educational content suitable for secondary SW convergence gifted education, and designed and developed it in detail. The composition of artificial intelligence education content consists of machine learning and tensor flow understanding, linear regression machine learning implementation for numerical prediction, and multiple linear regression-based price prediction machine learning implementations. The developed educational contents were verified by experts with qualitative aspects. In the future, we expect that the educational content of artificial intelligence proposed in this paper will be useful for strengthening the ability of SW convergence gifted teachers.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.1-7
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• 2016

The effects of five different cooking methods (boiling, steaming, grilling, microwaving, and superheated steaming) on proximate composition, pH, color, cooking loss, textural properties, and sensory characteristics of chicken steak were studied. Moisture content and lightness value (L*-value) were higher in superheated steam cooked chicken steak than that of the other cooking treatments such as boiling, steaming, grilling and microwaving cooking (p<0.05), whereas protein content, redness value (a*-value), hardness, gumminess, and chewiness of superheated steam cooked chicken steak was lower than that in the other cooking treatments (p<0.05). Fat content and ash content, springiness, and cohesiveness were not significantly different among the chicken steak cooked using various methods (p>0.05). Among the sensory characteristics, tenderness score, juiciness score and overall acceptability score were the highest for the superheated steam samples (p<0.05), whereas no difference in flavor scores were observed among the other treatments (p>0.05). These results show that marinated chicken steak treated with superheated steam in a preheated 250℃ oven and 380℃ steam for 5 min until core temperature reached 75℃ improved the quality characteristics and sensory properties the best. Therefore, superheated steam was useful to improve cooked chicken steak.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.150-156
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• 2000

Oligotrophic bacteria isolated from forest soil showed a specific community consisting of various taxonomic groups compared with those in other soil or aquatic habitats. Based on the cell shape, the isolates were divided into four groups: regular rod, curved/spiral rod, irregular rod, and prosthecate bacteria. The cellular fatty acids 60 oligotrophic isolates were analyzed. The 30 fatty acids which were identified or characterized are classified. At the dendrogram based on cellular fatty acid composition, four clusters(I-IV) were separated at a euclidian distance of about 50. Cluster 3 and 4-a strains were containing Q-8, these strains are accommodated in the Proteobacteria gamma and beta subdivision. The chemotaxonomic profiles of the cluster 4-a strains showed good agreement with those of the genus Burkholderia. Cluster 3 was characterized by the presence of branched-chain fatty acids, iso-C15:0, iso-C17:1, and iso-C17:0 as the major components. These chemotaxonomy suggested the close relationship of the isolates with Xathomonas/Sterotrophomonas group. Based on the 16S rDNA sequence analysis, the two representative strains(MH256 and MA828) of cluster 3 showed the close relation to genera, Xathomonas/Sterotrophomonas, but were not included in these genera. These strains were even further away from core Xanthomonas, and clearly were seen to branch outside the cluster formed by the Sterotrophomonas maltophilia. MH256 and MA828 16S rDNA sequence was different enough to put new genus on a separate branch. The isolates with Q-10 were also studied. They are corresponded to the two large groups in Proteobacteria alpha subdivision. One was incorporated in the genus Bradyrhizobium cluster, which also includes Agromonas, a genus for oligotrophic bacteria. The strains of the other group showed high similarity to the genus Agrobacterium.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.115-120
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• 2003

Changes in polyphenol, free sugar, and organic acid concentrations and their antioxidative activities in Korean pear during storage were investigated. The antioxidant activity of polyphenols was evaluated. Polyphenol concentration in different parts of pear, peel, pulp and core, reached 25.7%. pH decreased while concentrations of free sugars, including fructose, glucose, and sucrose, increased during storage. Four organic acids, citric malic, succinic, and fumaric acids, were determined. Succinic acid was the major organic acid in the pulp and decreased after 5 month of storage. The antioxidative of polyphenol fractions I, II, and III on cottonseed, linseed, and fish oils were higher than those of the control group.

• KSBB Journal
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• v.22 no.4
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• pp.239-243
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• 2007

A method of forming agar microcapsule with fibroin coating was developed in this report. The capsules were prepared from a W/O emulsion of hot agar in mineral oil and were subsequently coated by fibroin. The capsules were harvested as precipitated aggregates, which can be dispersed in an aqueous media. The diameter of the microcapsule was less than $10{\mu}m$ by microscopic observation and 90% of them were between $1.32{\mu}m\;and\;6.0{\mu}m$. The structure of the aggregates and their dispersed microspheres were investigated by scanning electron microscope. Confocal microscopy was applied to visualize the core-shell structure of the agar microcapsule with fibroin coating. Thermogravimetric analysis (TGA) measured their composition to be agar 51.2%, fibroin 13.8%, Span 80 1.4% by weight.