• Resources Recycling
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• v.9 no.4
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• pp.16-27
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• 2000

In order to produce raw material powder of advanced magnetic material by spray roasting process, newly modified spray roasting system was developed in this work. In this spray roasting system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, uniform temperature distribution inside reaction furnace made thermal decomposition process fully completed, and produced powder was effectively collected in cyclone and bag filter. This system equipped with apparatus which can purify hazard produced gas. In this study complex acid solution was prepared by dissolution of mill scale and ferro-Mn into the acid solution, and the pH of this complex acid solution was controlled about to 4. It was conformed that mill scale and ferro-Mn containing a lot of impurities such as $SiO_2$, P and Al could be used as raw material by reducing the impurities content of complex acid solution below 20 ppm. Complex oxide powder of Fe-Mn system was produced by spraying purified complex acid solution into the spray roaster through nozzle, and the variations of produced powder characters were studied by changing he reaction conditions such as reaction temperature, the injection velocity of solution and air, nozzle tip size and concentration of solution. The morphology of produced powder had spherical shape under the most experimental conditions, and concentration of solution. The morphology of produced powder has spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform, which tells the excellence of this spray roasting system. The grain size of most produced powder was below 100 nm. From the above results, it will be possible to produce ultra fine oxide powder from the chloride of Fe, Mn, Ni, Cu and rare earth by using this spray roasting system, and also to produce ultra fine pure metal powder by changing reaction atmosphere.

• Journal of Life Science
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• v.17 no.12
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• pp.1701-1708
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• 2007

Seed pelleting is generally conducted in order to save the labor for sowing and thinning by enabling the precision mechanical planting. In the present study, the influence of physical and chemical properties of pelleting solid materials was investigated on carrot seed germination. Among the pelleting solid materials evaluated, dialite, kaolin, and talc showed low bulk density and high porosity. Bentonite and dialite carried high water holding capacities of 184% and 173%, respectively, while calcium carbonate, calcium oxide, and fly ash showed relatively low water holding capacity. The pH of kaolin (6.8) and dialite (7.4) were close to neutral, while limestone (12.8), calcium oxide (13.0), and bentonite (10.0) were highly basic. High electro-conductivity was shown in limestone and calcium oxide. EDS analysis revealed that the main elemental compositions of talc were Si (71.0%) and Mg (29.0%), and those of calcium carbonate were Ca (66.6%), Si (22.9%), and Mg (10.5%). High granulation capacity was observed from talc and the mixture of talc and calcium carbonate. Seeds pelleted with bentonite showed the highest hardness. The dissolving type of the pellet layer after imbibition was split type in talc, limestone, zeolite, and fly ash, melt type in calcium carbonate and calcium oxide, and swell type in bentonite and vermiculite. The shortest dissolving time of pellet layer was observed from calcium carbonate and kaolin. The germination speed $(T_{50})$ was delayed as the size of pelleted seeds increased. The optimum size of pelleting was 19 ratio in carrot.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.459-465
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• 2002

To obtain the basic data for commercial 10% salted egg yolk for mayonnaise preparation, 3 types of egg yolks [pasteurized egg yolk (Yolk A)-not salted, pasteurized before salting (Yolk B)-salted, and pasteurized after salting (Yolk C)-salted] were prepared, and the changes in quality characteristics of these egg yolks with frozen storage were tested. The results obtained were as follows; Yolk A gelatinized during frozen storage, thus could not used for mayonnaise preparation. The viscosity of the egg yolk increased $3{\sim}5$ times after salting. Viscosity of the salted egg yolk increased with frozen storage time. Viscosity of Yolk B was higher at $-20^{\circ}C$ than $-15^{\circ}C$. Viscosity of Yolk C, however, was higher at $-15^{\circ}C$ than $-20^{\circ}C$. Frozen storage of pasteurized salted egg yolk showed some effects on the emulsification capacity. The effect, however, was smaller than that of unpasteurized salted egg yolk. Microbes of salted egg yolk were decreased with frozen storage, but there was no difference between Yolk B and Yolk C. It was suggested that commercially pasteurized 10% salted egg yolk for mayonnaise preparation can be successfully stored for 12 months at the temperature of $-15{\sim}-20^{\circ}C$.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.880-888
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• 2017

Palatability and texture analysis of nine Korean rice cultivars were investigated to select the most appropriate rice variety for the cooked-rice processing. The rice cultivars studied consisted of Samkwang, Seonpum, Wolbaek, Andabyeo, Dasan-1, Ilpum, Haiami, Jungsanggold and Chindle. They revealed the moisture, protein, amylose and starch contents of 10~12, 5~6, 12~19, and approximately 90%, respectively. Among the evaluated rice varieties, WB exhibited the lowest amylose content (12.7%) and Jungsanggold the next (17.2%). In the rapid-visco analyzer test, Jungsanggold, Chindle, Wolbaek and Seonpum revealed a low value of final and setback viscosities than other varieties. Using a toyo meter analyzer, Chindle, Haiami, Samkwang were selected as having high toyo palatability values, while Dasan-1, Wolbaek and Andabyeo revealed low values. Toughness and adhesiveness of all nine cooked rice varieties were highest in Jungsanggold, Chindle and Ilpum. Also, palatability of cooked rice was highest in the following order: Chindle (80.03) > Samkwang (76.21) > Jungsanggold (74.08). The results of this study suggest that Chindle may be effectively used to produce processed cooked rice.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.333-339
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• 2009

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included. Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 ${\mu}m$) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%. Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/$cm^2$. Teeth were thermocycled fivehundred times between $50^{\circ}C$and $550^{\circ}C$for 30s at each temperature. Electrical conductivity (${\mu}A$) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method. Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (${\mu}A$)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41). Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.

• Food Science and Preservation
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• v.19 no.4
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• pp.532-538
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• 2012

Seven rice varieties (Dasan, Keunseon, Goami, Baekjinju, Seolgaeng, Hangangchal and Heukseol) were used to study the physicochemical properties of dry milled (200-mesh) rice flour species. The moisture and crude protein contents of rice were 15.00-15.10% and 6.09-8.21%, respectively. The crude lipid and crude ash of rice were 0.21-1.02% and 0.37-1.62%, respectively. As for the Hunter's color value, the L value was highest in the Dasan flour (96.47); the a value was highest in the Heukseol flour (5.03); and the b value was highest in the Baekjinju flour (3.36). The water aborption index was highest in the Goami flour (1.45), and the water solubility index was highest in the Hangangchal flour (9.16%). The amylose contents of the rice flour species were highest in the Goami (26.42%) rice flour, followed by the Dasan (19.39%), Seolgaeng (19.24%), Keunseon (18.06%), Heukseol (15.52%), Baekjinju (9.16%), and Hangangchal (0.84%) rice flour. In the X-raydiffractin patterns of the diverse species, seven tice varieties showed A-type crystallinity. As for the amylogram properties, the initial pasting temperature was 58.00-$69.03^{\circ}C$. The maximum viscosity was highest in the Dasan flour. The Heukseol flour had the lowest maximum viscosity, breakdown, and setback. In terms of the thermal properties of the differential scanning calorimeter (DSC), the onset temperature was 59.03-$66.84^{\circ}C$; the peak temperature, 66-70-$72.82^{\circ}C$; and the end temperature, 74.06-$78.66^{\circ}C$. The enthalpy (${\Delta}H$) was lowest in the Heukseol flour (7.59 J/g) and highest in the Seolgaeng flour (11.36J/g).

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.749-755
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• 2021

The objective of this study was to investigate the physicochemical properties of rice starch extracted from stale rice using alkaline steeping (AKL) and improved enzymatic digestion (iENZ) methods. The crude protein content (0.5-0.7%) of stale rice starch (SRS) was less than 1% by iENZ, but not so when measured by the existing ENZ methods. SRS is an intermediate amylose rice starch. AKL-SRS and iENZ-SRS exhibited typical A-type crystal packing arrangements with similar relative crystallinities. iENZ-SRS showed higher gelatinization onset and peak temperatures with a narrower gelatinization temperature range, compared to those of AKL-SRS, indicating that iENZ annealed SRS. Thus, iENZ-SRS exhibited lower swelling power and solubility, and higher pasting viscosities with delayed viscosity development. Overall, the use of stale rice as a rice starch source could make economical production of rice starch possible, and iENZ may diversify rice starch characteristics, which expands the utilization of rice starch in food and non-food industries.

• Korean Journal of Heritage: History & Science
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• v.43 no.3
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• pp.144-179
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• 2010

Investigation into iron manufacture relics has been active since 1970s, especially accelerated in 1990s across the country. Consideration of the importance of production site relics has lately attracted attention to iron manufacture relics. Methodological studies of the investigation into iron manufacture relics, however, were less made compared with those of the investigation into tomb, dwelling, or swampy place relics. It is because the process of iron manufacture is too complicated to understand and also requires professional knowledge of metal engineering. With the recognition of these problems this research is to form an opinion about how to excavate, to rearrange and classify, and to examine iron manufacture relics, based upon the understanding of the nature of iron, iron production process, and metal engineering features of related relics like slag, iron lumps and so on. This research classifies iron manufacture relics into seven types according to the production process; mining, smelting, refining, tempering, melting, steelmaking, and the others. Then it arranges methods to survey in each stage of field study, trial digging, and excavation. It also explains how to classify and examine excavated relics, what field of natural science to be used to know the features of relics, and what efforts have been made to reconstruct a furnace and what their problems were, making the best use of examples, drawings, and photos. It comes to the conclusion, in spite of the lack of in-depth discussion on application and development of various investigation methods, that iron manufacture relics can be classified according to the production process, that natural sciences should be applied to get comprehensive understanding of relics as well as archeological knowledge, and that efforts to reconstruct a furnace should be continued from the aspect of experimental archeology.

• Korean Journal of Heritage: History & Science
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• v.49 no.2
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• pp.56-69
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• 2016

Flame resistant treatment has been applied since 1973 for fire prevention in historical wooden buildings, but several problems, such as whitening and discoloration are constantly occurring in some Dancheong, in spite of evaluation criteria. It is supposed that these phenomena are caused by the stability issue of flame retardant, Dancheong production methods, the residue of chemicals, which were applied in the past, building location environments, etc., but no evaluation and cause inspection has been performed. Therefore, this study aims to verify the effect of flame retardant on Dancheong by producing Pseudo-samples and setting spatial and temporal environment conditions. Pseudo-samples of Dancheong were produced using three methods; the method specified in the Standard Specification of Properties; the method, which is generally used in the site and the traditional method. For different environment conditions of pseudo-samples, the areas were classified into a coastal area and an inland area and the places were classified into a sunny place and a wetland. After applying a flame retardant, annual variations were inspected for 12 months and change aspects were observed through scan and regular observation. In annual variation inspection, various variations like whitening, decolorization, dissolution and exfoliation were found and especially, whitening was most dominant. When the effect of flame retardant depending on the production methods was analyzed, whitening occurred in all the three production methods. It is supposed that this is because calcium(Ca) was contained in the coloring material of each production method and it reacted with phosphorous(P) of flame retardant. When the effect of flame retardant depending on the environment conditions was analyzed, whitening occurred more in the coastal area than in the inland area and it reduced in the building in a sunny place, which was constructed using the traditional method. It is supposed that this results from the humidity change and the difference of glue used in each production method. In conclusion, for using a flame retardant containing phosphorous(P), there is a need to check if calcium components including Oyster Shell White were used in Dancheong in advance and to conduct various preliminary studies on place conditions and Dancheong construction conditions.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.209-217
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• 2022

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH₄H₂PO₄) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.