• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.41-54
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• 2023

Illite is a common mineral that forms readily from feldspar and mica via hydrothermal alteration and exhibits various characteristics depending on the degree of hydrothermal alteration. To ensure continued mining of high-quality illite ore, it is crucial to understand the illitization. Thus, this study collected ores from two illite ore deposit and their surrounding alteration zones in Yeongdong-gun, Chungcheongbuk-do, a significant source of illite in the Republic of Korea, to determine the constituent mineral contents and textural characteristics. Polarized light microscopy analyses revealed that the illite ore deposit were highly illitized with little remaining textural characteristics of the parent mica schist, and only some quartz was present. The ore zone contained illite, muscovite, quartz, and feldspar, with illitization primarily occurring around feldspar and quartz. X-ray diffraction analyses identified that the content of illite/muscovite was approximately 50-75 wt.%, with a maximum of 75 wt.%. Additionally, X-ray fluorescence analyses indicated a linear increase in K₂O content with increasing illite content, showing the highest correlation among the major components analyzed. It is suggested that the illite in the Yeongdong area results from feldspar and quartz alteration by hydrothermal fluids along the fault, with illitization of feldspar occurring before that of quartz. The results of this study are expected to contribute to the development of high-quality illite ore deposit in Yeongdong, Chungcheongbuk-do.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.95-106
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• 2023

Quartz (SiO₂) is among the major rock-forming minerals in the earth's crust. The atomistic structures of SiO₂ may evolve during diverse frictional processes. The reduction of friction of quartz-rock accompanied by its amorphization, hydration, and formation of silica gel provides mineralogical insights into earthquakes and related phenomena. Ball milling, together with rotary shear experiments have been useful to infer the atomic origins of such processes. In this study, optimal experimental conditions for ball milling for amorphization of SiO₂ were determined by taking into account various process variables. The crystallinity of SiO₂ gradually decreased and became amorphous as the ball milling time increased at a high milling speed. The degree of wear of the milling media and its effect on the amorphization of SiO₂ were analyzed using distinct milling materials (zirconia, stainless steel). The amount of ball wear increased with increasing milling time. Furthermore, the worn stainless steel particles from balls tend to interact with amorphized SiO₂ to form Si-O-Cr. These results aid in understanding the process of atomistic structural changes caused by ball milling of divserse materials with relatively high hardness, such as SiO₂, and understanding various geological friction processes.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.515-532
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• 2023

Bentonite, predominantly consists of expandable clay minerals, is considered to be the suitable buffering material in high-level radioactive waste disposal repository due to its large swelling property and low permeability. Additionally, the bentonite has large cation exchange capacity and specific surface area, and thus, it effectively retards the transport of leaked radionuclides to surrounding environments. This study aims to review the thermodynamic sorption models for four radionuclides (U, Am, Se, and Eu) and eight bentonites. Then, the thermodynamic sorption models and optimized sorption parameters were precisely analyzed by considering the experimental conditions in previous study. Here, the optimized sorption parameters showed that thermodynamic sorption models were related to experimental conditions such as types and concentrations of radionuclides, ionic strength, major competing cation, temperature, solid-to-liquid ratio, carbonate species, and mineralogical properties of bentonite. These results implied that the thermodynamic sorption models suggested by the optimization at specific experimental conditions had large uncertainty for application to various environmental conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.86-94
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• 1991

Volcanic ash soils were classified as Andepts, a suborder of the Inceptisols in Soil Taxonomy. Increased knowledge on the volcanic ash soils necessitated and facilitated considerable improvement in this system. As a result, the new Order of Andisols was incorporated in the 1990 edition of the Keys to Soil Taxonomy. The central concept of an Andisol is that of a soil developing in volcanic ejecta, and/or in volcaniclastic materials, whose colloidal fractions are dominated by short-range-order minerals or Al-humus complexes. Andic propertis of volcanic ash soil in Cheju Island were investigated. For this study, soils of toposequence distributed along the southern slope of Mt. Halla, and the major soil groups such as dark brown soils, very dark brown soils, black soils, and brown forest soils were collected and analyzed for Al, Fe and Si extracted with solutions of pyrophosphate, dithionite-citrate. and oxalate respectively. Weolpyeong and Yongheung soils developed on the lower elevations contain only small amounts of allophane and Al-and Fe-humus complexes. For other soils, allophane content decrease with elevation and increaes with soil depth,whereas Al-humus complexes increase with elevation and decrease with soil depth. Substantial amount of allophane and ferrihydrite are found in all horizons of Ora and Ara soils developed on 150-300m elevations and of Noro and Jeogag soils developed on cinder cones. In the A horizons of Pyeongdae, Tosan and Heugag soils developed on the higher elevations, Al-humus complexes are dominant form of Al reflecting low pH and high organic matter content. However, lower horizons are dominated by allophane.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.463-469
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• 2014

Sorghum has been consumed as one of the important staple food in the semiarid tropics of Africa and Asia. Sorghum is rich in starch, protein, essential vitamins and minerals and grows relatively well in dry climate regions when it compared with other staple food crops. Sorghum has taken an increased interest due to several studies that report about the beneficial effects of sorghum on human health. In the present study, we investigated the antioxidative and activity of extract of milling by-products (hull and bran) of Korean sorghum cultivar, 'Hwanggeaumchal' as well as its grain. Hull extract showed the highest total polyphenol contents ($29.7{\pm}0.2mg\;GAE/100g$) and major four pigments content ($322.6{\pm}14.5mg/100g$). From results of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate (ABTS) radical scavenging activity, hull extract ($IC_{50}$, $6.3{\pm}0.1{\mu}g/mL$) was also showed the strongest antioxidative effects. Bran and grain showed similar polyphenol, pigments contents and antioxidative effects. We determined cell viability by MTT assay and evaluated the anti-inflammatory activity by measuring nitric oxide (NO) of hull, bran and grain methanol extract (0.5% HCl v/v) on RAW 264.7 cells. Hull extract treatment was significantly decreased NO production with dose-dependant manner. Apigeninidin as one of the major pigment of hull was showed inhibitory activity against NO production without cytotoxicitiy. Therefore, sorghum milling by-products can be used as a good source of antioxidative and anti-inflammatory agents.

• Food Science of Animal Resources
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• v.29 no.4
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• pp.445-456
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• 2009

Colostrum samples were collected from 36 dairy farms in Gyeonggi-do and one dairy farm in the National Institute of Animal Science (NIAS) for testing. Colostrum samples were analyzed for phisycochemicals (specific gravity, pH, titratable acidity), general components (fat, protein, lactose, total solid, solid non-fat (SNF)), fatty acids, amino acids, minerals, microflora, somatic cells, and Ig (Immunoglobulin). The first colostrum revealed the following data: fat contents were $6.16{\pm}2.39%$, proteins were $14.78{\pm}4.30%$, lactose $2.57{\pm}0.77%$, total solid $24.28{\pm}4.36%$, and SNF $18.12{\pm}4.08%$, whereas the 2nd (or $12^{th}$) colostrum revealed $5.56{\pm}1.76%$ fat, $3.46{\pm}0.41%$ proteins, $4.19{\pm}0.43%$ lactose, $13.90{\pm}1.76%$ total solid, and $8.34{\pm}0.81%$ SNF. Also, the first colostrum revealed the contents of major amino acids as 0.89% aspartic acid, 0.71% threonine, 0.86% serine, 1.75% glutamic acid, 0.64% valine, 0.95% leucine, 0.83% lysine, and 0.95% proline, and those in the 10th colostrum were 0.25% aspartic acid, 0.15% threonine, 0.19% serine, 0.59% glutamic acid, 0.19% valine, 0.35% leucine, 0.31% lysine, and 0.34% proine. Major amino acid contents rapidly decreased as milking times increased. In the first colostrum, the following mineral contents were observed: there were 2,168 ppm in Ca, 1,959 ppm in P, 914 ppm in K, 761 ppm in Na, 287 ppm in Mg, 1.7 ppm in Fe, 14.3 ppm in Zn, and 1.0 ppm in Cu; while in the 10th colostrum, the following ppm contents were 1,389 in Ca, 1,323 in P, 838 in K, 427 in Na, 131 in Mg, 1.0 in Fe, 4.7 in Zn, and 1.3 in Cu. The mineral contents in a colostrum rapidly decreased as milking times increased.

• Journal of Mushroom
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• v.15 no.4
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• pp.229-236
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• 2017

This study was carried out to investigate the physicochemical characteristics of cultivated cereals by Phellinus linteus mycelium. Also, we investigated the content of free sugar, organic acid, free amino acid, mineral and fatty acid of cultivated cereals by P. linteus mycelium. The major free sugars were determined the glucose, maltose, and fucose by HPLC. The content of total free sugars was the highest in cultivated red rice by P. linteus mycelium at $36^{\circ}C$. The content of fucose was the highest in cultivated red rice by P. linteus mycelium at all cultivation temperatures. The organic acids were identified oxalic acid, malic acid, citric acid, and succinic acid, as in the case of free sugar, higher contents of organic acids were observed in the cultivated cereals by P. linteus mycelium than control. There was no significant difference in the mineral content between the control and cultivated cereals by P. linteus mycelium. Sixteen kind of free amino acid were detected in cultivated cereals by P. linteus mycelium. And the content of total free amino acids were higher in the cultivated cereals by P. linteus mycelium than the control. And essential amino acids showed significantly differences between control and cultivated cereals by P. linteus mycelium. Fatty acids were detected with seven kinds of fatty acids, and the major fatty acid was determined the linoleic acid by GC-MS. The content of linoleic acid was higher in the cultivated cereals by P. linteus mycelium than the control.

• Food Science and Preservation
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• v.19 no.1
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• pp.87-94
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• 2012

This study was carried out to investigate the physicochemical characteristics of maturating and dried jujube. The moisture contents of the unripe and ripe jujube were found to be 84.66 and 66.45%, respectively, but that of the dried jujube was 31.48%. The crude-fat and crude-ash contents of the dried jujube were much higher than those of the maturing jujube. The carbohydrate contents of the unripe, ripe, and dried jujube were found to be 13.51, 27.94, and 61.70%, respectively, and the soluble-protein contents were 0.88, 1.73, and 3.71%. The reducing-sugar content of the dried jujube was 18.82%, higher than that of the ripe jujube. The sucrose contents of the unripe and ripe jujube were 10.15 and 16.66 g/100 g, respectively, and that of the dried jujube was 33.46 g/100 g. The major fatty acids that were found to compose jujube were palmitic, oleic, pamitoleic, linoleic, and linolenic acid. The myristoleic and arachidonic acid contents were higher in the dried jujube than in the ripe jujube, but the palmitoleic acid content was lower in the dried jujube than in the ripe jujube. The major minerals of jujube were found to be Ca, K, Mg, and P, and the total mineral contents of the unripe, ripe, and dried jujube in this study were 343.38, 584.94, and 331.56 mg/100 g, respectively. The polyphenol contents of the unripe, ripe, and dried jujube were 309.12, 248.80, and 23.34 mg/100 g, respectively, while the vitamin C contents were 610.04, 310.22, and 423.27 mg/100 g.

• Food Science and Preservation
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• v.21 no.3
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• pp.373-380
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• 2014

This study was conducted to investigate the nutritional components and antioxidant activities of Nelumbo nucifera Gaertner flower (lotus flower, LF) and its wine (lotus flower wine, LF wine). The moisture, crude protein, crude fat, crude ash, and carbohydrate contents of the LF were 85.90, 1.91, 0.30, 1.04, and 10.85%, respectively, and of the LF wine, 92.87, 1.70, 0.30, 0.15, and 5.17%, respectively. The total amino acids in the LF and the LF wine were 2,168 and 6,341 mg/kg, respectively. Palmitic acid (38.63%) was a major fatty acid in the crude fat of the LF, and oleic acid (76.24%) was a major fatty acid in the crude fat of the LF wine. The levels of potassium in the LF ($390.91{\pm}9.60mg/100g$) and the LF wine ($27.40{\pm}1.86mg/100g$) were higher than those of the other minerals. The total phenol and flavonoid contents of both the lotus flower water extract (LFW) and the lotus flower ethanol extract (LFE) were higher than those of the LF wine. In addition, the highest antioxidant activities and ORAC values were obtained from the LFW and the LFE. In conclusion, we found that the LF and the LF wine have potential as natural antioxidants due to their higher bioactive compound contents such as their total phenol and flavonoid contents.