• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.145-150
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• 2020

The ship motion of large LNG ships affects ships' safety. The purpose of this study was to estimate the transfer function of roll motion among the hull motion of 153,000 m3 class LNG vessels. The ship motion transfer function was modeled using a Linear Time-Invarient system with single input, single output, and transfer function. The transfer function of the ship motion was estimated by the system identification method using single ocean wave as input of the model, and using the roll motion of the LNG ship obtained through ANSYS as the output of the model. The usefulness of the experimental results was evaluated using the precision and estimation rate of the model for cases wherein the different transfer function dimensions. Results of the experiment showed a precision at 99% and 98%, with estimation rate at 78% and 50%. From these results, we found the proposed method of estimating the transfer function of ship motion in this study reasonable. In the future, data of ship motion in actual sea conditions will be acquired and it will be applied to make the construction of models with multiple inputs and multiple outputs for practical use.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.2
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• pp.103-111
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• 2013

In this study, field measurements were conducted in the section about 7 km from sea dike to westward. The observations of along channel current were carried out, and water temperature and salinity were measured simultaneously at 10 stations during one tidal cycle, and sampling interval is 1 hour. The maximum ebb current is about 1.5 m/s at the surface layer but flood current is 0.4 m/s at the bottom layer during discharge period. Residual current during river discharge shows two layer structures which is typical characteristic of the estuary system. On the other hand, residual current during a period with no discharge has shown multi-layer structure different from general estuarine systems. The distribution of high salinity can be seen at the bottom layer as the effect of discharge does not reach down to the bottom layer during discharge. As a result, freshwater is not effected at the bottom layer during observation, and mixing of surface layer to bottom layer is reduced by stratification.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.177-183
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• 2006

The summer production of sweet pepper in Korea which cultured in the highland area such as Hapchon is essential for a year-round export, but has the problem, fruits lose easily those marketability. This study was carried out to find changes of fruit quality in response to storage on sweet pepper cultivars in summer. Seven cultivars of sweet peppers, 'Jubilee', 'Plenty', 'Goal', 'Romeca', 'Derby', 'Midas' and 'Maximalia' were obtained iron growers in Hapchon which was highland of 600-800m from sea level and stored at $10^{\circ}C$ with box packing. Fruit quality was evaluated every 4days up to 4weeks. The weight loss of 'Jubilee' was the lowest, that of 'Romeca' was the highest. The firmness of 'Goal' was maintained highly for 4weeks and the red cultivars was higher than those of other color cultivars. The lightness of 'Jubilee' was sensitively affected by storage duration. Seeds of 'Plenty' and 'Derby' were plentifully browned after 4weeks storage. The occurrence of fruit rotting was after 16-204ay storage and those of 'Plenty' and 'Maximalia' were the earliest. The marketability of 'Jubilee' and 'Romeca' maintained by 70% for 16 days was the highest, but most cultivars lost those by 20% after 24days storage. It may be suggested that the marketability of sweet pepper producted in summer can be stored at $10^{\circ}C$ for 2weeks to maintain that of 80%.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.1129-1140
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• 2018

Temporal and spatial characteristics of the frequency of several weather types and the change in air pollutant concentrations according to these weather types were analyzed over a decade (2007-2016) in seven major cities and a remote area in Korea. This analysis was performed using hourly (or daily) observed data of weather types (e.g., mist, haze, fog, precipitation, dust, and thunder and lighting) and air pollutant criteria ($PM_{10}$, $PM_{2.5}$, $O_3$, $NO_2$, CO, and $SO_2$). Overall, the most frequent weather type across all areas during the study period was found to be mist (39%), followed by precipitation (35%), haze (17%), and the other types (${\leq}4%$). In terms of regional frequency distributions, the highest frequency of haze (26%) was in Seoul (especially during winter and May-June), possibly due to the high population and air pollutant emission sources, while that of precipitation (47%) was in Jeju (summer and winter), due to its geographic location with the sea on four sides and a very high mountain. $PM_{10}$ concentrations for dust and haze were significantly higher in three cities (up to $250{\mu}g/m^3$ for dust in Incheon), whereas those for the other four types were relatively lower. The concentrations of $PM_{2.5}$ and its major precursor gases ($NO_2$ and $SO_2$) were higher (up to $69{\mu}g/m^3$, 48 ppb, and 16 ppb, respectively, for haze in Incheon) for haze and/or dust than for the other weather types. On the other hand, there were no distinct differences in the concentrations of $O_3$ and CO for the weather types. The overall results of this study confirm that the frequency of weather types and the related air quality depend on the geographic and environmental characteristics of the target areas.

• Journal of Food Hygiene and Safety
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• v.22 no.3
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• pp.179-191
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• 2007

The purpose of this study was to monitor and compare the contamination levels of heterotrophic bacteria and pathogenic bacteria (total coliforms, Escherichia coli O157:H7, Salmonella spp., Vibrio parachaemolyticus, Staphylococcus aureus and Bacillus cereus). The samples collected at fish farms located in the Jeju-island were investigated from March to August in 2006. The contamination levels of S. aureus, B. cereus and Salmonella spp. ranged $0-3.3{\times}10^2 CFU/ml,\;0-2.2{\times}10^2 CFU/ml\;and\;0-5.1{\times}10^1CFU/ml$, respectively, and 85% of moist pellet feeds were contaminated with S. aureus, B. cereus and total coliforms. But total coliforms and E. coli O157:H7 were not detected in oliver flounder (Paralichthys olivaceus). For the production of safe oliver flounder (Paralichthys olivaceus), education of sanitation for employees, control of fish feed, and continuous monitoring for microorganism will be required.

• Korean Journal of Medicinal Crop Science
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• v.13 no.4
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• pp.171-177
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• 2005

This study was carried out to investigate the distribution and habitat feature of Glehnia littoralis as a part of establishment of conservation plan for important natural agro-plant resources in South Korea. Habitat of Glehnia littoralis was generally found 28.2 m from high tide water line and 2.7 m above sea level at sand dunes near three seashore areas. Density and coverage of Glehnia littoralis were higher in east seashore among three seashore areas. The number of plant species growing with Glehnia littoralis in natural habitat was found 35 species. Among 35 species Ixeris repens Carex pumila, Carex kobomugi, Elymus mollis, Ischaemum anthephoroides, Imperata cylindrica var. koenigii were shown higher density and coverage. Average yearly precipitation and temperature of habitat for Glehnia littoralis were 1250.3 mm and $12.5^{\circ}C$, respectively. Among three seashores, the precipitation and temperature of south seashore were much more and higher than those of other two seashores. Soil characteristics of habitat for Glehnia littoralis were that average pH was 7.9 and organic matter was 0.23%. Content $P_2O_5$ and Ca were relatively higher, but the level K and Na were very low.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.8
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• pp.1233-1238
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• 2016

Combined treatment of chlorine dioxide ($ClO_2$) gas, mild heat, and fumaric acid was performed to reduce microbial growth and maintain quality of Citrus unshiu during storage at $4^{\circ}C$. Citrus unshiu fruits were treated with $ClO_2$ gas (15 or 30 ppmv), mild heat (40, 50, or $60^{\circ}C$), and fumaric acid (0.1, 0.3, or 0.5%). Combined treatment of 15 or 30 ppmv $ClO_2$ gas, $50^{\circ}C$ mild heat, and 0.5% fumaric acid reduced populations of inoculated Listeria monocytogenes by 3.5~3.7 log CFU/g. In addition, combined treatment decreased populations of yeast and molds in Citrus unshiu by 2.54 log CFU/g after 30-day storage at $4^{\circ}C$. Combined treatment also reduced the decay rate by 48% after 30 days of storage compared with the control. Total solid content, titratable acidity, and color values were not significantly affected by the combined treatment. Therefore, combined treatment of $ClO_2$ gas, mild heat, and fumaric acid can be a useful hurdle technology to improve microbial safety and quality of Citrus unshiu during storage.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.361-368
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• 2003

As the supply of aggregate needed in the construction site becomes difficult due to preservation of environment and exhaust of aggregate resource, a research for replacement aggregate in shortage is being actively progressed and a copper slag is also a kind of replacing aggregate. To use copper slag as fine aggregate of concrete, many studies are already conducted in each of the advanced countries and in the state of applying these at the site. In the year of 2000 a Korea industrial standard of Copper slag aggregate for concrete was established in our country so that this can be applied in the construction site. This study is to find out whether copper slag is equipped with the physical and chemical requirements for the use in concrete aggregate, and to analyze the dynamic properties of copper slag concrete that replaces 25, 50, 75, 100% of fine aggregate. Copper slag study not only satisfies the using condition of fine aggregate, but also reveals high level of physical property compared to ordinary concrete up to 50% of sand replacement rate. In the future after confirming the durability of concrete using copper slag, it is judged to be advantageous for the preservation of environment to use this as a replacement material for natural aggregate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.450-458
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• 2017

In this study, the antimicrobial activity of black garlic pomace extract (BGPE) was examined, and its washing applicability to spinach was investigated. BGPE had antimicrobial activity against both Gram-positive (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative (Escherichia coli O157:H7 and Salmonella Typhimurium) food-borne pathogens. In particular, antimicrobial activities of BGPE against Gram-positive bacteria were higher than those against Gram-negative bacteria. Spinach samples were treated with 0.5% BGPE to determine the effect of BGPE on reducing naturally existing microorganisms on the surface of spinach leaves. BGPE treatment reduced populations of total aerobic bacteria and yeast/molds in spinach by 1.23~1.35 log CFU/g and 0.82~1.12 log CFU/g during 9 days of storage, respectively, compared with those of control samples. After treatment, there were no significant differences in color quality such as Hunter L, a, and b values and total color difference (${\Delta}E$). These results clearly indicate that BGPE treatment can be useful for improving microbiological safety and maintaining color quality of spinach during storage.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.1-6
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• 2012

We studied that the effect of stocking density on growth and survival rate of the scallop, Chlamys farreri (initial shell height 32.97 mm and total weight 5.63 g) from June 2002 to October 2003 in the west coast of Korea. C. farreri is usually the west coast of Korea and northern China in the natural habitat of the coastal species. Range of surface water temperature in the study area was $4.3^{\circ}C$ to $25.3^{\circ}C$, salinity 29.2 psu to 32.1 psu, dissolved oxygen 5.32 mg/L to 7.51 mg/L and pH was 7.84 to 8.12, respectively. The stocking densities were 20, 30, 40 and 50 individuals per a compartment of suspension cage in culture beginning. After 16 months from initiation, ranges of shell height and mean total weight were from 64.35 mm to 76.23 mm and from 41.53 g to 64.85 g. The survival rate was from 82% to 100%. The growth rate of the scallop was negatively correlated with the stocking density. The growth of the shell height and total weight were decreased with decreasing of water temperature. Most of mortality of scallop occurred during March to April and September to October. Survival rate in the stocking density was decreased by density increase and was highest in 20 individual a compartment.