• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.237-247
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• 1991

To characterize the community structure and spatial distribution of phytoplankton, observations on seawater temperature, salinity, nutrients, primary productivity and abundance and species composition of phytoplankton were made in the polar front region and its neighborhood off the east coast of Korea in summer 1990. Among the 96 taxa identified, Rhizosolenia setigera and Thalassionema nitzschioides were the most dominant species. The assemblage at the surface and 50 m depth was quite different in the northern inshore part of the study area but similar in the southern and offshore part. Principal component analysis by the species abundance showed that the phytoplankton consisted of the communities representing the surface of the northern inshore part with the neritic-warm dinoflagellates, the Northern Korean Cold Water with the cold water diatoms and the southern and offshore part, which seems to represent the Eastern Korean Warm Water, with the warm water diatoms. At the frontal region, diatoms were mixed with warm and cold water species. Primary productivity and phytoplankton standing crops were higher at the front than the neighboring waters. Nutrients were markedly high at the Northern Korean Cold Water. Horizontal advection of the Northern Korean Cold Water accompanied by nutrient supply seems to contribute to the high phytoplankton biomass at the front.

• KSBB Journal
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• v.17 no.4
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• pp.381-387
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• 2002

A filamentous fungus, strain FB01 showing high $\beta$-glucosidase activity was isolated from a compost. This fungus was cocultured with Trichoderma viride to enhance the productivity of $\beta$-glucosidase by changing inoculation time of the fungus. The microbial consortium showed higher cellulolytic enzyme production than T. viride alone. The maximal enzyme production was obtained when the microbial consortium was cultured at 30$\^{C}$ and pH 6.0 for 10 days with the activities of CMCase, $\beta$-glucosidase, and avicelase of 2.0, 0.8, and 0.2 U/mL, respectively. These enzyme activities were 2, 4, and 2 times as high as those of CMCase, p-glucosidase, avicelase from T. viride, respectively, indicating that a synergistic interaction appeared between T. viride and strain FBOI . The serial subcultures with pH control increased $\beta$-glucosidase production about 3.2 times. Enzyme production using ricestraw as a carbon source showed that the activities of CMCase, $\beta$-glucosidase, and avicelase were 3.69, 0.76, 0.17 U/mL, respectively, and $\beta$-glucosidase activity was 1.5 times higher than that of T viride.

• Journal of the Korean Geosynthetics Society
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• v.12 no.3
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• pp.65-73
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• 2013

The information of cut slope in Mt. Jang area, Busan is investigated in order to construct the Slope Management System in Urban Area. The slope inspection sheet is made to record the characteristics for cut slopes, and that is capable to be inputted slope information systematically. The cut slopes in Mt. Jang area are consisting of 69 slopes. Most of the cut slopes are constructed in cutting slope and retaining wall (CR). The cut slopes located in housing facilities are 46 slopes, and the slopes located in school facilities are 12 slopes. The traverse of cut slopes is mainly ranged from 50 m to 150 m, and the height is mainly ranged from 10 m to 20 m. The slopes combined with soil and rock are mostly distributed. The retaining wall was installed in the toe part of cut slope in order to increase the slope stability, and the additional reinforcement methods including the anchor, drainage, preventing rock fall, shotcrete and vegetation were installed at the toe part of cut slopes.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.79-90
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• 1997

The purpose of this study was to evaluate the substantivity of experimentally developed gel type tetracycline HCl and a mixture of tetracycline-citric acid gel, and compare to those of solution type tetracycline HCl. 11 extracted anterior teeth were subjected to this study. After scaling and root planing teeth were randomly divided into 3 treatments groups : group 1; 3 teeth were irrigated with tetracycline HCl(50mg/ml) solution , group 2; tetracycline gel (5%) was inserted in the periodontal pockets of 3 teeth, group 3; a mixture of tetracycline and citric acid gel was inserted in the pockets of 3 teeth. And 2 teeth treated in 0.9 % sterile saline served as controls. After 5-minute exposure, each tooth immediately extracted and incubated at room temperature for 22 days in tris-buffered saline as a desorption media. The total volume of TBS was removed and replaced with fresh TBS, at 24-h intervals. Removed desorption media transferred to a sterile vial and stored at -70 oC. This procedure was repeated every 24 h throughout the 22-day desorption period. Using Porphyromonas gingivalis as an indicator organism, a microtiter assay was used to evaluate antimicrobial activity desorbed from the teeth. 1. 50mg/ml tetracycline HCl solution exhibited the longest antimicrobial activity. Compared to saline treated group, it showed significant difference on the day 1 and day 2 desorption period. 2. The ODs of 5% tetracycline gel and a mixture of tetracycline-citric acid gel were significantly different during the first 24 hour only. 3. There was no statistically significant difference after the day 3 between the groups.(p<0.05). Despite our expectation a mixture of tetracycline-citric acid gel did not show longer antimicrobial activities than those of tetracycline gel, and the solution type exhibited the longest activities. Because the gel type agents may stay in the subgingival environment longer than the solution, if the teeth were not extracted immediately after the delivery of the agent, the result could be different. hus this result suggests the possibilities of practical use of these kind of gel type agents.

• The Korean Journal of Food And Nutrition
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• v.17 no.1
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• pp.1-7
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• 2004

Yoghurt base was prepared from skim milk added with 0.25∼2.0%(w/v) of chlorella extract powder and fermented with lactic acid bacteria(Streptococcus thermophilus : Lactobacillus casei = 1:1) at 37$^{\circ}C$ for 24 hours. Quality characteristics of the yoghurts were evaluated in terms of acid production, number of viable cell, color, texture property, and sensory property during lactic acid fermentation. The addition of 0.25% chlorella extract powder stimulated the growth of lactic acid bacteria which showed the highest number of viable cell counts(l.46${\times}$10$\^$8/ CFU/mL) after 12 hours incubation, and also enhanced the acid production which was pH 4.33 after 12 hours incubation. The L values(brightness) of the yoghurts containing chlorella extract powder were lower than control group, whereas the b values(yellowness) were higher. The hardness and gumminess of the yoghurt added with 0.25% chlorella extract powder were higher than others. Sensory scores of the yoghurt added with 0.25% chlorella extract powder were significantly higher than other groups in color, chlorella odor, sweet taste, chlorella taste, mouth feel, aftertaste and overall acceptability.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.884-891
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• 2016

A secondary injection system in a diesel engine has benefits: it can be controlled independently without interrupting engine control, it can be adapted to various layouts for exhaust systems, and it pose no reductant dilution problems compared to post injection systems in the combustion chamber or other supplemental reductant injections. In a secondary injection system, the efficiency of the catalyst depends on the method of reducing the supply. The reductant needs to be maintained and optimized with constant pressure, the positions and angles of injector is a very important factor. The concentration and amount of reductant can be changed by adjusting secondary injection conditions. However, secondary injection is highly dependent upon the type of injector, injection pressure, atomization, spray technology, etc. Therefore, it is necessary to establish injection conditions the spray characteristics must be well-understood, such as spray penetration, sauter mean diameter, spray angle, injection quantity, etc. Uniform distribution of the reductant corresponding to the maximum NOx reduction in the DeNOx catalyst system must also assured. With this goal in mind, the spray characteristics and impingement plate types of a secondary injector were analyzed using visualization and digital image processing techniques.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.290-295
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• 2013

The purpose of this study was to investigate the shear bond strength between various commercial all-ceramic system core and veneering ceramics, and evaluate the clinical stability by comparing the conventional metal ceramic system. The test samples were divided into three groups: Ni-Cr alloy (metal bond), yttria-stabilized, tetragonal zirconia polycrystal (Y-TZP) (zirconia bond), lithium disilicate (lithium disilicate bond). The veneering porcelain recommended by the manufacturer for each type of material was fired to the core. After firing, the specimens were subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.50 mm/min until failure. Average shear strengths (mega pascal) were analyzed with a one-way analysis of variance and the Tukey test (${\alpha}$=0.05). The mean shear bond strength${\pm}$SD in MPa was $44.79{\pm}2.31$ in the Ni-Cr alloy group, $28.32{\pm}4.41$ in the Y-TZP group, $15.91{\pm}1.39$ in the Lithium disilicate group. The ANOVA showed a significant difference among groups (p<0.05). None of the all-ceramic system core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.

• Clean Technology
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• v.19 no.4
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• pp.410-415
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• 2013

The supercapacitors were fabricated using silver (Ag) nano paste and activated carbon paste on the polyimide (PI) film and 5% potassium polyacrylate (PAAK) was used for gel electrolyte. In this paper, the current collector film and the electrode film were fabricated using screen printing. The thickness of printed silver paste was $7.3{\mu}m$ and the sheet resistance has the range of $5-7m{\Omega}/square$. An activated carbon with a surface area of $1,968m^2/g$, an electronic conducting agent (SUPER P, TIMCAL) and poly (4-vinylphenol) were mixed in 2-(2-buthoxyethoxy) ethyl acetate (BCA) with a ratio of 7:1:3 to fabricate the electrode paste. To analyze electrochemical characteristics, cyclic voltammetry was performed to evaluate the stability of the devices under the voltage range of -0.5-0.5 V. The calculated specific capacitances were 44.04 and 8.62 F/g for 10 and 500 mV/s scan rates, respectively.

• Journal of Digital Contents Society
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• v.17 no.5
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• pp.317-327
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• 2016

Flipped learning is a new learning technique which can maximize the learning effect by mixing two or more different learning environments including online & offline, and recently introduced system: 'Google classroom' is the optimized internet platform for flipped learning. This study tried to apply flipped learning to regular course 2nd grade dental students(n=70) and evaluated the satisfaction of students. The subjects of periodontology and operative dentistry were chosen to evaluate flipped learning model for regular course 2nd grade dental students(n=70). Each class consisted of six classes, and three times of them were performed in conventional classes and the other three times were in flipped learning method by using Google classroom. Evaluation of satisfaction progressed at the end of class. In this study, application of flipped learning in the dental college classes showed high efficiency in terms of degree of understanding, self-directed learning and motivation. Collectively, it was shown that flipped learning using Google classroom can be a reliable platform in dental classes.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.422-427
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• 1994

The quality of salted and semi-dried mackerel prepared by cold osmotic dehydration using a high osmotic pressure resin during storage at $5{\pm}1^{\circ}C$ was evaluated. The moisture contents in salted and semi-dried mackerel decreased in. range of 4 during storage. The brown pigment formation content and peroxide value of salted and semi-dried mackerel prepared by osmotic dehydration were more lower than those of salted and semi-dried mackerel prepared by traditional drying methods such as sun-drying, hot-air drying and cold air drying. The viable cell count and histamine contents of cold osmotic dried products were much lower and revealed a tendency to increase during storage, but even these values after storage of 15 days showed that the salted and semi-dried mackerel was safety in respect of food sanitation. The ratio of saline soluble nitrogen to total nitrogen in cold osmotic dried products were higher than that of traditional dried products during storage. Judging from the results of chemical and sensory evaluation, shelf-life of salted and semi-dried mackerel by cold osmotic drying were more longer than that of salted and semi-dried mackerel prepared by traditional drying.