• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.435-445
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• 2007

Ship structures are thin-walled structures and lots of cutouts, for example, of inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed. In the present paper, we investigated several kinds of perforated stiffened model from actual ship structure and series of elasto-plastic large deflection analyses were performed to investigate into the influence of perforation on the buckling and ultimate strength of the perforated stiffened plate varying the cutout ratio, web height, thickness and type of cross-section by commercial FEA program(ANSYS). Closed-form formulas for predicting the ultimate strength of the perforated stiffened plate are empirically derived by curve fitting based on the Finite Element Analysis results. These formulas are used to evaluate the ultimate strength, which showed good correlation with FEM results. These results will be useful for evaluating the ultimate strength of the perforated stiffened plate in the preliminary design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.425-436
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• 2019

This study constructs independent potential variables that are variables expected to affect child abuse reporting intention of child care teachers. In addition, this study establishes a research model based on the relationships between potential variables according to the results of previous studies and planning behavior theory. The purpose of this study was to examine what factors affect and how reporting intention is determined. The subjects of this study included a convenience sample of nursery teachers working in 67 daycare centers in the C region. The following results were obtained. First, the research model proposed in this study was found to be a suitable model to explain the child abuse teacher's intention to report child abuse through the analysis of the measurement and structural models. Second, the child abuse teacher's knowledge of child abuse is an important factor explaining the reporting intention and has an indirect effect through the mediation. Third, attitudes toward reporting of child care teachers were found to be the most direct factor that predicts reporting intentions. Fourth, subjective norms and reporting intentions of child care teachers were not statistically significant. Bsead on these results, basic data for improving child abuse reporting rate of childcare teachers were presented.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.139-144
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• 2006

Chestnut trees have been severely damaged by the various cankers in Korea. Field surveys for elucidating the relationships between disease occurrence and environmental factors, i.e., tree age, temperature, rainfall precipitation, direction, degree of slope, chemical properties of soils, and so on, were carried out in the chestnut tree plantations located at Gyeongnam, Jeonnam, Chungnam, and Gyeonggi-Do Province. Totally, one thousand and one hundred thirty seven trees from 36 experiment plots were investigated. Trees infected by at least one of the canker fungi were estimated up to 66%. The most severely infested area was Sunchon in Jeonnam Province with the rate of 80%, while the most lightly infested area was Kongju in Chungnam Province with 39%. Disease occurrence was found to be highly correlated with tree age. The disease occurred most frequently on trees ranged from 7 to 12 years old, while it was relatively low on trees below 5 years old or above 25 years old. Canker positions on the tree formed by the pathogenic fungi were most often at 1.6-2.0m above the ground. Over five hundreds bark samples from the canker area on the tree were collected and the pathogenic fungi were isolated. The most commonly isolated fungus was identified as Cryphonectria parasitica, the chestnut blight fungus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.636-642
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• 2007

In order to develop a novel food utilization of germinated brown rice, physicochemical properties of germinated brown rice and its extrudates were investigated. The physical characteristics, the paste viscosity, and the anti-oxidation activity were analyzed. Brown rice was soaked for 10 hr and germinated for 24 and 48 hr at $30^{\circ}C$. Extrusion conditions of brown rice and germinated brown rice were barrel temperature at 100 and $120^{\circ}C$ and moisture content at 20%. The expansion ratio increased with the increase in germination time. It increased at barrel temperature of $100^{\circ}C$, and decreased at $120^{\circ}C$. The bulk density showed negative corporations with the expansion ratio. The paste viscosity of germinated brown rice was decreased with the increase in the germination time. However the paste viscosity of extrudates was lower as barrel temperature increased. Content of polyphenolic compound in extrudates was increased by increasing germination time and barrel temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.113-119
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• 2003

A feeding trial was carried out to Investigate the effect of lipid level and herb mixture in the diets on growth of juvenile parrot fish, Oplegnathus fasciatus. Two plicate groups of fish averaging 4.5 g were fed four experimental diets containing herb mixture (0 and 5 g/kg diet) at each of two lipid levels $(8\%\;and\;16\%)$ for 8 months from summer to spring (water temperature, $7.2-25.4^{\circ}C)$. Weight gain improved with increasing dietary lipid level or supplementation of herb mixture during the first 4 months feeding period. Weight gain of fish fed the diet containing $16\%$ lipid level was significantly higher (P<0.05) than that of fish fed the diet containing $8\%$ lipid level. Weight gain of fish fed the diet with herb mixture was significantly higher (P<0.05) than that of fish fed the diet without herb at the $16\%$ lipid level. Feed efficiency was influenced by dietary lipid level or herb mixture during the first 4 months. On the other hand, weight gain and feed efficiency were not affected by dietary lipid level and herb mixture after 4 months until end of feeing period. Survival of fish fed the diet containing $8\%$ lipid without supplementation of herb mixture was the lowest among the groups (P<0.05). Lipid contents of liver and viscera tended to increase with increasing dietary lipid level during the first 4 months feeding period, however muscle lipid content was not influenced by dietary lipid and herb. Total cholesterol of serum was influenced by dietary lipid level during the first 4 months feeding period. These results indicate that an increase of dietary lipid level from $8\%\;to\;16\%$ and supplementation of herb mixture can improve growth performance of juvenile parrot fish when water temperature is optimum for growth such as the summer season in Korea.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.51-58
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• 2020

This study redesigned the Korean speaking classes to foreign undergraduate students as flipped learning classes and verified their effect on speaking-related emotional variables. In addition, international students' perceptions of what experiences are needed to improve speaking efficacy in Korean were examined. For this purpose, the 'Creative speaking' subject for freshmen was redesigned to flipped learning class and operated for one semester. To analyze the effect of speech-related emotions, a paired t-test was conducted on 26 foreign students' pre-post scores of speech efficacy and anxiety. Also awareness of experiences needed to improve speech efficacy was surveyed and content analysis was conducted. As the result, the speaking efficacy of students after flipped-learning has been significantly improved. This means that flipped learning classes for the Korean speaking are effective for the positive emotions of foreign students speaking Korean. In addition, international students perceived that Korean speaking efficacy can be improved by practicing speaking in Korean, learning with Korean colleagues. Based on these results, several discussions and suggestions were presented.

• Asian Journal of Atmospheric Environment
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• v.7 no.4
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• pp.177-190
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• 2013

Air pollution trends in Japan between 1970 and 2012 were analyzed, and the impact of air pollution countermeasures was evaluated. Concentrations of CO decreased from 1970 to 2012, and in 2012, the Japanese environmental quality standard (EQS) for CO was satisfied. Concentrations of $SO_2$ dropped markedly in the 1970s, owing to use of desulfurization technologies and low-sulfur heavy oil. Major reductions in the sulfur content of diesel fuel in the 1990s resulted in further decreases of $SO_2$ levels. In 2012, the EQS for $SO_2$ was satisfied at most air quality monitoring stations. Concentrations of $NO_2$ decreased from 1970 to 1985, but increased from 1985 to 1995. After 1995, $NO_2$ concentrations decreased, especially after 2006. In 2012, the EQS for $NO_2$ was satisfied at most air quality monitoring stations, except those alongside roads. The annual mean for the daily maximum concentrations of photochemical oxidants (OX) increased from 1980 to 2010, but after 2006, the $98^{th}$ percentile values of the OX concentrations decreased. In 2012, the EQS for OX was not satisfied at most air quality monitoring stations. Non-methane hydrocarbon (NMHC) concentrations generally decreased from 1976 to 2012. In 2011, NMHC concentrations near roads and in the general environment were nearly the same. The concentration of suspended particulate matter (SPM) generally decreased. In 2011, the EQS for SPM was satisfied at 69.2% of ambient air monitoring stations, and 72.9% of roadside air-monitoring stations. Impacts from mineral dust from continental Asia were especially pronounced in the western part of Japan in spring, and year-round variation was large. The concentration of $PM_{2.5}$ generally decreased, but the EQS for $PM_{2.5}$ is still not satisfied. The air pollution trends were closely synchronized with promulgation of regulations designed to limit pollutant emissions. Trans-boundary OX and $PM_{2.5}$ has become a big issue which contains global warming chemical species such as ozone and black carbon (so called SLCP: Short Lived Climate Pollutants). Cobeneficial reduction approach for these pollutants will be important to improve both in regional and global atmospheric environmental conditions.

• Journal of Life Science
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• v.19 no.1
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• pp.34-39
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• 2009

Alginate with a MW of 1,283 kDa was hydrolyzed with 0.4 M organic acids at $100^{\circ}C$ for 3 hr. Molecular weights of alginates hydrolyzed with organic acids ranged from 7.5 to 53.2 kDa. There was no significant difference in the molar ratio of mannuronate to guluronate in alginates hydrolyzed with organic acids. Acetic add was found to be the most effective organic acid for hydrolysis of alginate. The MW of alginate decreased with increasing concentration and reaction time with acetic acid as a hydrolyzing agent. The correlations between the MW of hydrolyzed alginate and concentration of acetic acid as well as reaction time with 0.4 M acetic acid were plotted and the relevant equations obtained in this study. Polymannuronate and polyguluronate were isolated by pH adjustment of alginate hydrolyzed with 0.4 M acetic add. The molar percentages of mannuronate in polymannuronates isolated from alginate hydrolyzed with 0.4 M acetic acid at $100^{\circ}C$ were increasing in proportional to the reaction time such as 75% for 1 hr, 90% for 3 hr, and 98% for 5 hr of reaction time.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.311-318
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• 2000

The purpose of this study was to determine the optimum water intaking depth for water treatment plant based on the changes of phytoplankton distributions in Unmun reservoir. Sampling was carried around of intaking tower near the Dam site at monthly intervals from February to Ocotber in 1998. Total 79 phytoplankton taxa were observed and they were classified into 4 varieties, 75 species within 51 genera. Diatoms were mainly dominated from February to July. However Rhodomonas sp. was a dominant species in August, and Microcystis ichthyblabe in September and October. Cell density of 122,800 cells/mL in October was the highest, and 415 cells/mL in May was the lowest. The pattern of vertical distribution was similar until May; however, the cell density in the epilimnion was much higher than it in the hypolimnion during the periods with the high water temperature over $20^{\circ}C$ since June. The water depths showing over 5,000 cells/mL ranged from the surface to 9m in June, surface to 6m in September, and on the only surface in October. Based on water temperature and phytoplankton vertical distribution, the depth of 6m appeared to be the optimum intaking depth far water treatment plant: 75.4 to 98.0% of phytoplankton cell densities could be avoided and the temperature over $18.3^{\circ}C$ was preserved to prevent cold water damage for rice growth at the water depth during cyanobacterial blooming period in Unmun reservoir.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.257-264
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• 1997

To find out the influence of different rice varieties on the emission of methane in the soil and the exudation of carbohydrates from root, the experiment was conducted on a fine silty, mesic family of Aeric Fluventinc Haplaquepts (Jeonbug series). The varities of rise involved one early maturing variety of Japonica type(namweon) and three mid-to-late maturing varieties of Japonica type and one mid-to-late variety of Indica${\times}$Japonica crossed. The methane flux over the rice canopy was measured according to the closed chamber method modified by Shin and the methane concentration in the soil was measured using porous cup installed in the soil. The carbohydrate exudates from root were measured under nutrient solution culture. It was found that the methane flux tended to be lower in early maturing varieties than in the mid-to-late maturing varieties, lower in indica${\times}$Japonica crossed variety than in Japonica type varieties. There was positive correlation between the number of tillers and the weight of roots of rice plant and methane flux. The correlation, however, tended to be greater between the weight of roots and methane flux. There was no significant difference in the concentration of methane in the soil under different varieties of rice, excepting one variety, Kehwa under which methane concentration was highest. In case of carbohydrate exudation, early maturing variety tended to be higher than other varieties, although the opposite was the case in methane flux.