• Journal of Conservation Science
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• v.34 no.2
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• pp.87-96
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• 2018

This study analyzed the influence of folding time on the forge welded bar and hammer scale produced using the traditional refining and forge welding reproduction experiment. In the case of the forge welded bar, increasing the forging time decreased the percentage of impurities and porosity from 26.09% to 1.8%. Additionally, the hardness increased by an average of 36.88 HV. In other words, the microstructure gradually became more precise. For the hammer scale, the amount of T Fe increased with forging time. X-ray diffraction analysis revealed the presence of quartz, fayalite, $w{\ddot{u}stite$, and magnetite. The amount of quartz decreased as the forging time increased. In addition, as the forging time increased, the granular $w{\ddot{u}stite$ changed into a cohesive, long, white band. The results provide information on the characteristics of the forge welded bar and hammer scale produced in the refining and forging process. This information can be used as technical data for ancient steel making processes as well as for future technological systems.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.146-154
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• 2002

To assess the adsorption and removal mechanism of dissolved inorganic nutrients in seawater by scattering yellow loess, a laboratory experiment was conducted for the change of nutrient concentration in seawater during the course of time depending on particle size and scattered concentration of the yellow loess. Twenty four hours after the addition of yellow loess in the size range of 0 $\mu$m to 500 $\mu$m in seawater, the removal rate of dissolved inorganic phosphorus (DIP) was increased with increasing amount of yellow loess. There was little difference among the removal rates depending on the size of yellow loess. On average, $26\%$ of dissolved inorganic silicate was reduced for the same period. No greate difference among the removal rate depending on both size and amount of yellow loess was found. Our results suggested that the removal mechanism of DU seemed to be associated with mostly the chemical bond with iron. More than $99\%$ of initial DU concentration was likely to be removed by this mechanism. In the case of inorganic dissolved silicate, the removal mechanism was likely to be attributed to a cation exchange between the yellow loess and seawater.

• Journal of the Korean institute of surface engineering
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• v.40 no.6
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• pp.254-257
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• 2007

TiN coating on tool steel has been widely used for the improvement of durability of tools. In this work, radical nitriding(RN) is carried out on SKD61 at $450^{\circ}C$ for 5 hours in the ammonia gas pressure $2.7{\times}10^3\;Pa$. The TiN coating is carried out by arc ion plating(AIP) with the process parameters: arc power 150 A, bias voltage -50V, coating time 40 minutes and nitrogen gas pressure $4{\times}10^3\;Pa$. Hardness, elastic modulus, friction coefficient and adhesion of TiN coating on substrates of both TiN/SKD61 and TiN/RN SKD61 coatings are investigated comparatively. The primary crystalline faces of TiN surface are(200) and(111) for TiN/SKD61 and TiN/RN SKD61 respectively. In addition to the primary phase, Fe phase exists in TiN/SKD61 coating, but not in TIN/RN SKD61. The hardness of TiN/RN SKD61 is about 700 Hv, 250 Hv(56%) higher than that of TiN/SKD61 at the near interface of TiN and substrates. At the TiN surface, hardness of TiN/RN SKD61 is 2,149 Hv, 71 Hv(3%) higher than that of TiN/SKD61. The elastic modulus of TiN coating is improved to 26.7 GPa(6%) by radical nitriding. The adhesion is improved by the RN coating showing no spalling. buckling and chipping on the scratch test track which are shown on the non-RN TiN/SKD61.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1143-1150
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• 2005

Antioxidative activities of 5 common edible seaweeds in Korea, three brown algae (seaweed fusiforme, sea mustard, sea tangle), one green algae (sea lettuce) and one red algae (laver), were examined. The antioxidative activities of ethanol extracts from these seaweeds were examined by measuring of inhibition rates against iron-induced linoleate peroxidation, DPPH (1,1-diphenyl -2-picrylhydrazyl) radical generation and MDA-BSA (malondialdehyde-bovine serum albumin) conjugation. Sea lettuce ethanol extract showed the strongest anti-oxidative activity among them, especially in inhibition against conjugation of lipid peroxide and protein. Second to sea lettuce, laver and sea tangle ethanol extracts showed high DPPH radical scavenging activity and inhibition against MDA-BSA conjugation. However, seaweed fusiforme and sea mustard ethanol extracts did not show antioxidative activities. Sea mustard contained the highest total flavonoids (11.33 mg/g dry wt) and sea lettuce contained the highest total polyphenol (8.97 mg/g dry wt) among these seaweeds. In addition, there was strong positive correlation between the antioxidative activity and total polyphenol content in these seaweeds, suggesting polyphenol compounds may contribute to antioxidative effect of seaweeds. From these data, it is suggested to consume much of seaweeds such as sea lettuce, laver and sea tangle to prevent age-related chronic diseases, and also develope neutraceutical products using polyphenol rich fraction from sea lettuce.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.787-799
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• 2013

The aim of this study was to investigate the accumulation of metallic elements and the control effect of marine pollution caused by ocean dumping in the sediments at a waste disposal area in the Yellow Sea. In July 2009, concentrations of organic matter and metallic elements (Al, Fe, As, Cd, Cr, Co, Hg, Ni, Mn, Pb, and Zn) were measured in surface sediments at the site. The ignition loss (IL) in the surface sediments showed a mean value of 15.4%, about 1.5 times higher than the mean value of the sediments in the coastal areas of Korea. The chemical oxygen demand (COD) at some disposal sites exceeded 20 mg $O_2/g{\cdot}dry$, which signifies the initial concentration of marine sediment pollutants in Japan. The disposal sites contain higher concentrations of Cr, Cu and Zn than the sediments of bays and estuaries that might be contaminated. The magnitude of both metal enrichment factors (EF) and adverse biological effects suggest that pollution with Cr and Ni occurred due to the dumping of waste in the study area. In addition, the geoaccumulation index (Igeo) showed that the surface sediments were moderately contaminated. By the mid-2000s, when the amount of waste dumped at this site was the highest, the concentration of metallic elements was higher than ever recorded. On the other hand, in 2008-09, the need for environmental management was relatively low compare with the peak. As a result, the quality of marine sediment has been enhanced, considering the effect of waste reduction and natural dilution in the disposal area.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.71-81
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• 2007

The marble-type dolomite from the Jasung Mine, which was farmed by duplicated affects of contact metamorphism and subsequent hydrothermal alteration, corresponds to a high-purity dolomite ranging up to above 98wt.% in dolomite contents. The dolomite contain minor impurities such as quartz, muscovite, and pyrite. It is characteristic that the dolomite is fairy Fe-rich corresponding to 0.4 wt.% due to the presence of pyrite of possible hydrothermal origin. The dolomite is nearly white-colored and constituting with subhedral crystals ranging $0.35{\sim}0.46mm$M in size, forming equigranular texture. Compared to the typical high-Ca limestone from the Pungchon Formation, the powder characteristics of dolomite is rather superior in milling efficiency, yields of fine particles, and size distribution. In addition, except for iron contents, the dolomite powder is no less superior than the limestone in quality and characteristics as fillers with respects to not only whiteness, oil absorption, and specific surface area but also shape characters such as elongation ratio, aspect ratio, and sphericity. This good characteristics of dolomite powder seem to be originated basically from comparatively higher grade and crystallinity of dolomite. Higher iron contents and the presence of sulfides prevents the dolomite from application for uses by thermal treatment, except for metallic manufacture. However, if proper ore separation procedure is available, the dolomite can be sufficiently utilized as substitutes for high-Ca limestone in most fields of filler industries.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.11
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• pp.1350-1357
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• 2017

General component and mineral contents according to species of Capsicum annuum were investigated. In addition, chuichung cucumber, white dadagi cucumber, and yellowish overripe cucumber were cooked by using seven different methods (boiling, steaming, pan-cooking, roasting, pan-frying, deep-frying, and microwaving), and retention rates of general components and minerals according to species were evaluated. Weight loss was observed in all cucumber species using all cooking methods. Most general component and mineral contents of C. annuum samples were significantly different according to species, and cooking method (P<0.05), whereas Fe and Cu contents were not significantly affected by species and cooking method, respectively. As a result, the highest protein, fat, ash contents were detected in deep-fried C. annuum, and high moisture contents were detected in raw, boiled, and steamed C. annuum. High mineral contents were detected in roasted and microwaved chuichung cucumber, deep-fried white dadagi cucumber and yellowish overripe cucumber. Retention rates of C. annuum by cooking method, ranged from 30~100% for protein, 10~100% for fat, 35~90% for moisture, and 30~100% for ash. High retention rates were observed for minerals in boiled, roasted, and microwaved chuichung cucumber, and deep-fried white dadagi cucumber and yellowish overripe cucumber. However, in yellowish overripe cucumber, mineral retentions rate were remarkably lowered by boiling and steaming, resulting in rates of 20~45%. These results were the data used as the basis for development of cucumbers.

• Journal of Dairy Science and Biotechnology
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• v.35 no.4
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• pp.255-261
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• 2017

The purpose of this study was to investigate the probiotic properties and antioxidant capacity of lactic acid bacteria isolated from Vietnamese feces and the Korean traditional food kimchi. Six isolated strains were identified as Lactobacillus sp. by 16S rRNA sequencing. All strains showed good resistance to low pH (1.5, 2.0, and 3.0) and 0.3% oxgall bile acids. Culture filtrates from the six strains showed various antioxidant effects, including DPPH, ABTS, reducing power, and metal chelating ($Fe^{2+}$) activities. Two of the six Lactobacillus strains showed potential probiotic activity. Heat resistance and adhesion assays were conducted by mixing the selected strains, Lactobacillus acidophilus V4, Lactobacillus plantarum V7, and Lactobacillus paracasei DK121 isolated from kimchi. The results showed that the heat resistance of these strains was similar to that of a commercial strain, L. plantarum LP. In addition, a mucin attachment assay using the mixture of selected strains (V4, V7, and DK121) showed high binding activity to the mucous layer. In conclusion, a mixture of V4, V7, and DK121 shows promising probiotic activity and may be useful for the development of health-related products.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.211-216
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• 2011

In this study, the effects of growth temperature on structural and optical properties of hydrothermally grown ZnO nanorod arrays have been investigated. Zinc nitrate ($Zn(NO_3)_2$) and hexamethylenetetramine were used as precursors. The ZnO buffered Si(100) with a thickness of 40 nm was used as the substrates. The ZnO nanorods were grown on these substrates with the temperature ranging from 55 to $115^{\circ}C$. The results were characterized by scanning electron microscope, X-ray diffraction and room temperature photoluminescence measurements. Well-aligned ZnO nanorods arrays were obtained from all samples. The tips of nanorods were flat when the temperature was less than $95^{\circ}C$, and the sharp-tip nanoneedle-like morphologies were obtained with the temperature of $115^{\circ}C$. In addition, some bundles were on the nanorods arrays with $115^{\circ}C$ due to the non-equilibrium growth. The growth temperature could affect the crystal and optical properties of ZnO. For the effects on crystal properties, the intensity of (002) peak was increased as the temperature was increased to $75^{\circ}C$, then decreased as the temperature was further increased to $115^{\circ}C$. As for the effects on optical properties, the intensity ratio of UV peak to visible peak is increased with the temperature increasing and the strongest UV peak intensity was obtained with the growth temperature of $95^{\circ}C$.

• Journal of Veterinary Clinics
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• v.31 no.6
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• pp.502-506
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• 2014

Recently nano particles have proven for wide array of bioactive properties. In the present study, antibacterial properties of chitosan silver nano composites (CAgNCs) were investigated against fish pathogenic Edwardsiella tarda. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CAgNCs against E. tarda were $25{\mu}g/mL$ and $125{\mu}g/mL$, respectively. The field emission scanning electron microscope (FE-SEM) image of CAgNCs treated E. tarda showed the strongly damaged bacteria cells than non-treated bacteria. Furthermore, treatment of CAgNCs induced the level of intracellular reactive oxygen species (ROS) in E. tarda cells in concentration and time dependent manner suggesting that it may generate oxidative stress leading to bacterial cell death. In addition, MTT assay results showed that the lowest cell viability at $100{\mu}g/mL$ of CAgNCs treated E. tarda. Overall results of this study suggest that CAgNCs is a potential antibacterial agent to control pathogenic bacteria.