• Korean Journal of Weed Science
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• v.14 no.2
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• pp.144-155
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• 1994

Scanning electron micrography and Transmission electron micrography studies were performed on the surfaces of stem(coleoptiles) of rice and barnyardgrass under various cropping patterns at 5 days after seeding or transplanting. Stem surfaces of rice under dry condition possessed rodlet-like epicuticular waxes, trichomes, stomata and cork cell layer in both broadcast and drilled rice while barnyardgrass had only thread-like epicuticular waxes, but trichomes, stomata and cork cell layers were not found. However, rice under water condition has no rodlet-like waxes, stomata and cork cells, and barnyardgrass was similar to that under dry condition. On the other hand, those on stems of 8-day and 25-day transplanted rice were well arranged and developed compared with those of direct seeded rice. Electron micrography showed significant difference in thickness of outer epidermal cell walls of rice and barnyardgrass under dry, water and transplanting condition. Thickness of outer epidermal cell was greater in transplanted rice, dry direct seeded rice, water-direct seeded rice and barnyardgrass in descending order.

• Journal of fish pathology
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• v.26 no.3
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• pp.193-206
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• 2013

The ark shell, Scapharca broughtonii is a marine bivalve mollusks belonging to the family Arcidae and important seafood for Korean and Japanese, and southern coast is brisk bays for the ark shell aquaculture. However, productivity of ark shell from these regions were rapidly reduced during the last decade due to mass mortality. The reason of this great damage has not yet been identified. To overcome this economic loss, diverse investigations were focused on environmental factors that affects in the physiology of S. broughtonii, but microbiological researches were performed insufficiently. Hemoglobin is one of the major blood component of ark shell and is damaged by some species of bacterial toxins. We concentrated on this red pigment because hemolysis could be the cause of ark shell mortality. In this study, we analyzed microbial diversity of underwater sediments in coastal regions and also existences in the body of S. broughtonii. We investigate about 4,200 isolates collected from June to September for microbial diversity of sediments and ark shell. We screened all of culturable microorganisms, and identified 25 genera 118 species, 24 genera 89 species, 30 genera 109 species and 39 genera 141 species, and selected 140 unique colonies for identification and challenge assay.

• Food Science and Preservation
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• v.22 no.2
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• pp.197-203
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• 2015

We investigated quality changes in dumpling shells by addition of various concentrations of dropwort powder. Dumpling shells were added with 0, 1, 3, 5, and 7%. dropwort powder respectively. Their water-binding capacity, weight, volume, and turbidity increased after cooking. As the added dropwort powder increased, their DPPH radical scavenging activity significantly increased (p<0.001). In addition, their L and a values decreased whereas their b value increased. In terms of the textural characteristics, the hardness and springiness increased and the cohesiveness and brittleness of the cooked dumpling shells significantly increased with an increasing content of dropwort powder. The savory taste, moisture, and chewiness of the dumpling shells prepared with the addition of 3% dropwort powder were preferred. Overall, the sensory evaluation showed that the sensory characteristics of the dumpling shells were best with the addition of 3% dropwort powder.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.2
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• pp.193-217
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• 2019

Researchers have observed one student who had difficulty in formulating a division equation. In the context of determination of a unit rate problem based on one student's case and previous research, we tried to examine in detail how students expressed the division formula, how to select the dividend and the divisor, and how they learned about those. First, a questionnaire was developed to analyze student's reactions and applied to the research participants. Interviews were conducted to discover how the participants choose the dividends and divisors derived from their cognitive characteristics corresponding to their selection method. The research exposed that the majority of the participants had difficulty in deciding the dividends and divisors. Moreover, the research indicated information that teaching methods need to be reformed. Finally, we obtained suggestions to place emphasis on how to decide a dividend and a divisor, why they made such selection and what the equation means. We proposed a learning method for the research above.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.757-762
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• 2010

Owing to the high specific strength and stiffness of composite materials, they are extensively used in mechanical systems and in vehicle industries. However, most mechanical structures experience repeated load and fatigue. Therefore, it is important to perform fatigue analysis of fiber-reinforced composites. The properties of composite laminates vary depending upon the stacking sequence and stacking direction. Fatigue damage of composite laminates occurs according to the following sequence: matrix cracking, delamination, and fiber breakage. In this study, fatigue tests were performed for damage analysis. Fatigue damages, which have to be considered in fatigue analysis, are determined by using the stiffness values calculated from hysteresis loops, and the obtained fatigue damage curve is examined using Mao's equation and Abdelal's equation.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.23-27
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• 1994

Nutrient culture study was initiated to examine the selectivity of dithiopyr(S, S-dimethyl 2-difluoromethyl)-4-(2-methylpropyl)-6-(trifluoro methyl)-3, 5-pyridine dicarbothiate) in rice(Oryza sativa L.) and barnyardgrass(Echinochloa crusgalli Beauv.). Absorption and translocation of $^{14}C$-dithiopyr in rice and barnyardgrass were also investigated to determine their selective mechanism. Rice was very tolerant, but barnyardgrass was susceptible to dithiopyr. The absorption of dithiopyr was greater in barnyardgrass than in rice and most of them remained in the roots of both species. Dithiopyr was absorbed by roots and basal shoots of both species. Translocation of dithiopyr was very low but was higher in barnyardgrass than in rice. Therefore, this study suggest that the selectivity of dithiopyr between rice and barnyardgrass may be mainly attributed to the absorption and translocation of dithiopyr in plants.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.2
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• pp.1-18
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• 2017

Metal fatigue is an important aging mechanism that material characteristics can be deteriorated when even a small load is applied repeatedly. An accurate fatigue evaluation is very important for component structural integrity and reliability. In the design stage of a nuclear power plant, the fatigue evaluations of the Class 1 components have to be performed. However, operating experience shows that the design evaluation can be very conservative due to conservatism in the transient severity and number of occurrence. Therefore, the fatigue monitoring system has been considered as a practical mean to ensure safe operation of the nuclear power plants. The fatigue monitoring system can quantify accumulated fatigue damage up to date for various plant conditions. The purpose of this paper is to describe the fatigue monitoring procedure and to introduce the fatigue monitoring program developed by the authors. The feasibility of the fatigue monitoring program is demonstrated by comparing with the actual operating data and finite element analysis results.

• Journal of the Economic Geographical Society of Korea
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• v.6 no.2
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• pp.471-486
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• 2003

Gentrification, the revitalization of inner city areas, encompasses both the changes in social and demographic composition and the alterations in the physical and economic nature of built environment. This urban phenomenon has received the bulk of attention since the 1970s, and simultaneously provided one prominent stage for the theoretical or ideological debates in the field of urban geography. Given this context, this paper deals with the consumption-based and production-based approaches to gentrification, both of which are involved in such debates. Specifically, this paper critically reviews and evaluates David Ley's and Neil Smith's explanations representing the two approaches, respectively. On the basis of the two urban geographers' seminal works published in the 1980s, this paper discusses the limitations of each explanation as a partial explanation.

• Food Science and Preservation
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• v.10 no.4
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• pp.498-505
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• 2003

This was studied to evaluate the rheology properties of the Dumpling shell added chitosans(commercial and prepared from fungal), polyphosphate, guargum and tapioca. The physicochemical properties of fungal chitosans (FCs95 and FCs 40) were as follows respectively. The nitrogen was 6.71% and 6.9％, the solubility 99.05% and 99.13％, the viscosity 2.23cps and 2.21cps, the acetylation 12.0% and 12.7% and the molecular weight 3.12${\times}$10$\^$5/Dalton and 3.01${\times}$10$\^$5/Dalton. From the above facts, the components and physicochemical properties of two kinds of fungal chitosan had little difference. The addition of polyphosphate, guargum and tapioca showed effect on the texture parameters(hardness, cohesiveness, springiness and gumminess) of Dumpling shell dough and the optimum addition concentration wag 0.074%, 6.59% and 0.062%(w/w), respectively. In case of chiotsans addition, texture of the dough by added SCs, FCs95 and FCs40 showed effect.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.432-442
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• 2022

This study aimed to investigate depression, fatigue, and role-overload in nurses caring for COVID-19 patients and identify factors affecting depression. Data were collected from 142 nurses caring for COVID-19 patients at four designated COVID-19 hospitals using self-report questionnaires, from September 8, 2020, to September 17, 2020. The subjects' scores for depression, fatigue, and role-overload were 14.51±9.54, 3.19±0.64, and 3.30±0.64 points, respectively. Depression was positively correlated with fatigue (r=.40, p<.001) and role-overload (r=.30, p<.001), and fatigue was positively correlated with role-overload (r=.54, p<.001). Factors affecting depression included fatigue (β=.23, p=.014), health status (moderate: β=.28, p=.001; unhealthy: β=.26, p=.002), and hospital type (university hospital: β=.18, p=.024). The explanatory power (R²) of the model was 28.1%. In order to manage the nurse's depression level, a strategy for lowering the fatigue level and a strategy for improving the nurse's health statue are needed.