• Geotechnical Engineering
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• v.14 no.1
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• pp.109-126
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• 1998

The use of fly ash as a contaminant barrier material was studied. Mixing ratio of fly ash to bentonite to meet the requirements for landfill liners was determined. The hydraulic behavior exhibited by the fly ash-bentonite liner and the effects of CaO were investigated through hydraulic conductivity tests under various conditions and microscopic analyses including XRD, SEM, helium porosimetry, and image analysis. The hydraulic conductivity of compacted fly ash decreased with the addition of bentonite, which was due mainly to the expanding of bentonite and partly to the filling of voids by chemical reaction products among constituents of the artificial liner. Because of insufficient CaO content, and rich in content but low-reactive $SiO_2$ contained in the fly ashes used, pozzolanic reaction and resulting effects in the artificial liner were not significant. The reactions among constituting materials and their resulting effects on hydraulic conductivity were controlled not by the apparent amounts of each constituent, but by reaction activities of the materials in the artificial liner.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.341-346
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• 1998

The effects of CaO, $CaO+MgSO_4$, and $CaO+MgSO_4$+compound fertilizers(NPK) on soil chemical properties of acidified forest soils were studied in Quercus spp. and Pinus rigida stands in Mt. Namsan and Mt. Surak in urban areas, and Kwangnung in a mountain area. The soil samples were collected in November 1995 after every year fertilization from November 1991 through April 1995. The fertilizations affected soil chemical properties. Soil pH increased after fertilizations compared with control. However, the effect was different between the stand types and the areas. Organic matter and total nitrogen content were not changed, while exchangable cations such as calcium and magnesium increased after fertilizations. However, these ration concentrations after fertilizer treatments were lower in P. rigida than in Quercus spp. stands. These rations also showed increased leaching characteristics more in the urban area than in the mountain area.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.535-544
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• 2013

Influence of sulfate on the early hydration in the solidification treatment of abandoned mine tailings was characterized. Solidified specimens using hydrated lime as a binder were prepared with various amounts of added $Na_2SO_4$ and different curing days. Unconfined compressive strength measurement, heavy metal leaching test, XRD analysis were performed after 7-, 14- and 28-days curing. According to curing days strength of solidified specimens using only distilled water increased but those with addition of $Na_2SO_4$ decreased. External cracks of specimens developed definitely with increasing $Na_2SO_4$ concentration and curing days. Concentrations of Cu, Cd, Zn, and As in the leached solutions from solidified specimens decreased significantly but Pb was leached readily in cases of hydrated lime dosage more than 10 wt%. Gypsum and $MgSO_4$ were identified in the cracked solidified specimens by XRD analysis, and pillar-shaped crystals of SEM image were identified as gypsum in reference with EDS analysis. Crystallization of sulfate in the process of lime-tailing solidification caused cracking, which should be supplemented for solidification treatment of highly sulfur-contained tailing.

• Journal of Animal Environmental Science
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• v.15 no.2
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• pp.155-160
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• 2009

This study was carried out to investigate the feasibility of Multi Process of Aerobic Digestion (MPAD) for recycling of swine manure slurry as fertilizer. MPAD consisted of three kinds of difference process which are thermophilic aerobic oxidation (TAO) system, lime solidification system, and reverse osmosis (R/O) membrane system. TAO system was studied well previously for decade. The chemical composition of the lime-treated solid fertilizer was as like that organic matter 17.4%, moisture 34.1%, N 0.9%, P 1.7%, K 0.3%, Ca 12.7%, and which was expected to be useful as acid soil amendment material. The concentrated liquid material produced by R/O membrane system was also expected as a good fertilizer for crops production and soil fertility improvement.

• Journal of Conservation Science
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• v.29 no.4
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• pp.367-378
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• 2013

Microstructures and nonmetallic inclusions of five forged iron axes and one cast iron axe were analyzed. The axes were excavated from the Proto-Three Kingdom Period site located in Yangchon, Gimpo. The forging objects were made of almost pure iron and low carbon steel, and only one among five were quenched after its figuration. Malleable cast iron structures showing on the casting suggest that the decarbonized casting method were applied. According to the results of nonmetallic inclusion analysis, the axes were produced by hammering the iron bloom which was attained with low-temperature -solid-reduction-method. Showing higher Fe content over $SiO_2$, it is assumed that the re-collecting rate of Fe was low because of the insufficient forging temperature and the impurities were included during the smelting process. It is assumed that the lime was used as a preparation because of detecting high Ca contents.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.271-275
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• 2013

Cobalt (Co) compounds have been used for centuries to impart rich blue color to glass, glazes and ceramics. Cobalt monoxide (CoO), an oxide of Co, is an inorganic compound that has long been used as a coloring agent in the ceramic industry. Unlike other coloring agents, CoO can be used to develop colors other than blue, and several factors such as its concentration in the glaze and firing condition have been suggested as possible mechanisms. For example, CoO produces a typical blue color called "cobalt blue" at very low concentrations such as 1 wt% in both oxidation and reduction firing conditions; a higher concentration of CoO (5 wt%) develops a darker blue color under the same firing conditions. Interestingly, CoO also develops a purple color at high concentrations above 10 wt%. In this study, we examined the applicability and mechanism of a novel purple glaze containing cobalt(II, III) oxide, one of the well characterized cobalt oxides. Experimental results show that an Augite crystal isoform (Augite-Fe/Co) in which Fe was replaced with Co is the main component contributing to the formation of the purple color. Based on these results, we developed a glaze using chemically synthesized Augite-Fe/Co crystal as a color pigment. Purple color glaze was successfully developed by the addition of 6~15 wt% of $Co_3O_4$ to magnesia lime.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.112-118
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• 2012

Steel industry produces many by-products and wastes such as blast furnace slag, electric arc furnace slag, and converter slag. As in the case of rock, the main component of steel slag are CaO and $SiO_2$ ; further, steel slag is as alkaline as portland cement or concrete. Electric arc furnace oxidizing slag is possible to use as an aggregate for concrete ; however, it has been reclaimed because of it's expansibility caused by free CaO. Recently, a innovative rapid cooling method for melting steel slag has been developed in Korea, which reduces free lime content to minimum level and increases the stability of iron oxide. Therefore, this study describes the results of a series of research to utilize globular shape of electric arc furnace oxidizing slag fine aggregates made by rapidly cooled method for the construction industry by cooling rapidly melted slag from the steel industry. First of all, an experiment was carried out to investigate the quality characteristics of rapidly cooled electric arc furnace oxidizing slag fine aggregates in order to determine whether they can be applied to the construction industry. Then, by applying them to concrete of various particle sizes, we explored experimentally the desired condition to apply rapidly cooled electric arc furnace oxidizing slag fine aggregates to concrete.

• Resources Recycling
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• v.33 no.2
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• pp.46-53
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• 2024

The residual heat and high CaO content present in the slag remaining in the ladle after the completion of continuous casting in the electric arc furnace (EAF) steelmaking process have been utilized to reduce power consumption and lime usage in the ladle furnace (LF) process. However, if the timing of such processes does not align with the LF and continuous casting operations, the recycling rate will decrease. To increase the slag recycling rate, the effect of ladle slag recycling methods, specifically pouring ladle slag into the slag pot in advance for subsequent recycling, on LF operations was analyzed. The slag liquefaction rate was calculated using the thermodynamic program Factsage 8.3 for ladle molten slag recycling methods. By applying each of the 10 heats operations for the ladle slag recycling methods, the desulfurization ability and LF operation performance were compared. It was found that when slag was immediately recycled into the ladle after continuous casting was completed, power consumption decreased by 0.3 MWh, LF operation time was shortened by 1.2 minutes, and the desulfurization rate increased by 5.8%.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.6
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• pp.497-508
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• 2017

This study aimed to investigate correlations between concentrations of extractable Arsenic (As) with varying chemical solutions (0.1 M $Ca(NO_3)_2$, 0.1 M $(NH_4)2HPO_4$, 0.5 M EDTA, Mehlich 3, and 0.5 M $NaHCO_3$) and those of As in crops, and then to seek the most suitable soil extraction method for predicting the potential of As uptake in crops cultivated in soils contaminated with As. For a mesocosm experiment, pepper (Capsicum annuum L.), soybean (Glycine max L.), and rice (Oryza sativa L.) were cultivated for three months in pots containing soils taken from the arable areas near abandoned mines in Korea. Following the cultivation, soil pH and DOC significantly increased by treatments of lime and lime plus compost, respectively, while insignificant influences in changing total and all extractable As concentrations were found in all soils. Arsenic concentration in edible part of all crops considerably depended on the extractable As concentration in the soils, particularly with Mehlich 3. All extractable As concentrations in the soils of C. annuum and G. max were significantly correlated with As concentration in their edible parts. For O. sativa, the extractable concentrations of Mehlich 3 ($R^2$: 0.18 at p: 0.006) and EDTA ($R^2$: 0.11 at p: 0.036) showed only marked relationships with As concentration in the edible part. These results may indicate that the Mehlich 3 and EDTA are soil extractants to determine phytoavailable As in soil that provide better prediction for As transfer from soil to crop.

• Conservation Science in Museum
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• v.14
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• pp.37-60
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• 2013

Conservation and analysis of wall painting Goguryeo was performed to classify the unknown fragments. The conservation naked eye observation, optical microscopy, and infrared examination were carried out in order to figure out the structure, quality of constituting materials, and damages such as cracks, and discolored fragments of colored areas. Based on such investigation, conservation was proceeded. and it was completed with strengthening the weakened pigment layer of wall blocks. In addition tombs where the wall painting fragments were excavated were investigated by making comparison with gelatin dry plates and copies possessed by National Museum of Korea. According to the result, they were Kaemachong, Gosan-ri Tomb No.1 Gamsinchong, and Wonbong-ri Tomb. The components of colors with which Goguryeo wall painting fragments were painted and the mineral pigments of the wall layer were analyzed. Portable µ-XRF spectrometer and X-ray diffractometer were employed. It showed that lime (CaCO₃) used for the wall layer, and the brown color is hematite(Fe₂O₃) and cerusite (PbCO₃) and lead oxide(PbO) were identified. In the red color, cinnabar (HgS) were detected.