• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.139-152
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• 2006

A spent fuel storage cask is required to prove the safety of a canister under a hypothetical accidental drop condition. A hypothetical accidental drop condition means that a canister is assumed to be a lee drop on to a pad of the storage cask during loading it into a storage cask. A pad of the storage cask absorbs shock to maintain the structural integrities of a canister under a hypothetical accidental drop condition. In this paper a finite element analysis for various pad structures was carried out to improve the structural integrity of a canister under a hypothetical accidental drop condition. A pad of a storage cask was designed a steel structure with concrete. The 1/4 height of a pad was modified with a structure composed of a steel and a polyurethane foam as a impact limiter. The effect of a shape of a steel structure was studied. The effects of the thickness of a steel structure and the density of a polyurethane foam was also studied.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.3-11
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• 2009

The increased demand and consumption of coal has intensified problems associated with disposal of solid waste generated in utilization of coal. Major utilization of coal by-products has been in construction-related applications. Since fly ash accounts for the part of the production of utility waste, the majority of scientific investigations have focused on its utilization in a multitude of use, while little attention has been directed to the use of bottom ash. As a consequence of this neglect, a large amount of bottom ash has been stockpiled. However, the need to obtain safe and economical solution for its proper utilization has been more urgent. The study presented herein is designed to ascertain the performance characteristics of bottom ash, as autoclaved lightweight foamed concrete product. The laboratory test results indicated that tobermorite was generated when bottom ash was used as materials for hydro-thermal reaction. According to the analysis of variance, at the fresh state, water ratio affects on flow and slurry density of autoclaved lightweight foamed concrete, but foam ratio influences on slurry density, while, at the hardened state, foam ratio affects on the density of dry and the compressive strength but doesn't affect on flexural and tensile strength. In the results of response surface analysis, to obtain target performance, the most suitable mix condition for lightweight foamed concrete using bottom ash was water ratio of 70$\sim$80% and foaming ratio of 90$\sim$100%.

• Resources Recycling
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• v.7 no.3
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• pp.11-16
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was t$\xi$sted by precipitate flotation using a sodium lauryl sulfate as a c collector. The effects of initial cobalt ion concentration, pH, surfactant concentration, flotation time, gas flow rate and foreign i ions on removal efficiency of cobalt ion were studied. Pretreatment of the waste liquid with 35% $H_2O_2$, prior to precipitate f flotation made shin of optimal flotation pH from the strong alkalinity to weak alkaline range and made a favorable flotation of c cobalt ion in wide range of pH. For the result of this experiment, 99.8% removal efficiency was obtained on the conditions of initial coball ion concentration 50 ppm, pH 9.5 gas flow rate 70 mllmin, flotation time 30 min. The simulate ion was fanned t to be the most harmful ion against removal of cobalt by precipitate flotation of the species which were tested The presence of 0.1 M of $SO_4^{2-}$ ion decreased remo,때 $\xi$폐iciency of cobalt to 90% while the cobalt were almost entirely removed in the a absence of sulfate ion.

• Resources Recycling
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• v.31 no.6
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• pp.44-51
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• 2022

In the steelmaking process using an electric arc furnace (EAF), light-burnt dolomite, which is a flux containing MgO, is used to protect refractory materials and improve desulfurization ability. Furthermore, a recarburizing agent is added to reduce energy consumption via slag foaming and to induce the deoxidation effect. Herein, a waste MgO-C based refractory material was used to achieve the aforementioned effects economically. The waste MgO-C refractory materials contain a significant amount of MgO and graphite components; however, most of these materials are currently discarded instead of being recycled. The mass recycling of waste MgO-C refractory materials would be achievable if their applicability as a flux for steelmaking is proven. Therefore, experiments were performed using a target composition range similar to the commercial EAF slag composition. A pre-melted base slag was prepared by mixing SiO₂, Al₂O₃, and FeO in an alumina crucible and heating at 1450℃ for 1 h or more. Subsequently, a mixed flux #2 (a mixture of light-burnt dolomite, waste MgO-C based refractory material, and limestone) was added to the prepared pre-melted base slag and a melting reaction test was performed. Injecting the pre-melted base slag with the flux facilitates the formation of the target EAF slag. These results were compared with that of mixed flux #1 (a mixture of light-burnt dolomite and limestone), which is a conventional steelmaking flux, and the possibility of replacement was evaluated. To obtain a reliable evaluation, characterization techniques like X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) spectrometry were used, and slag foam height, slag basicity, and Fe recovery were calculated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.226-234
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• 2017

The physical properties of lightweight foamed concrete mixed with EPS waste and flame resistant EPS waste were investigated. For this purpose, the main variables considered were a cement content of 300 and $400kgf/m^3$ and an EPS replacement ratio of 0, 10, 20, 30, and 40% by the volume ratio of the foam. The water-cement ratio and the dilution concentration were fixed to 0.5 and 10% respectively. The test results showed that the apparent density meets degrees 0.5 and 0.6 of KS F4039, and they showed little difference between the two mixes of Type A and Type B, regardless of the unit cement content. The bending strength obtained through the compressive strength also met the degree of KS F 4039. The thermal conductivity was 1~3% higher for the mixes of EPS than the case of flame resistant EPS, but both mixes met the 0.4 degree of KS F4039. The absorption ratio showed the values above 20% with a 1~3% difference for the two mixes, which mean further studies will be needed to reduce the absorption ratio.

• Resources Recycling
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• v.14 no.2
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• pp.19-27
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• 2005

The recycling possibility of aluminum waste dross(AWD) as a ceramic raw material of porous light-weight material was examined. A aluminum waste dross was washed 4-7 consecutive times and roasted at 900$^{\circ}% for 1hour as pre-treatments. The properties of the pre-treatment of aluminum waste dross was investigated. It was conformed by XRD result that the spinel crystalline was grown in AWD, after roasting. After the roasted AWD was ground in aqueous state, the sodium hexaphosphate(SHP) as a dispersant which is used for stabilizing the concentrated slurry was added to the AWD slurry. The porous material was prepared by slurry foaming method with surfactant at room temperature. The foamed slurry volumes were 2 and 3 times of the original slurry volume. The properties of porous material with extended volume of 3 times was following: the porosity was about 84%, bulk density was 0.59 g/cm$^3$, the range of pore was from 50 ${\mu}m$ to 500 ${\mu}m$ and mean pore size was about 200 ${\mu}m$. AWD porous material was sintered at 1150$^{\circ}C-1250$^{\circ}C. It was colcluded that AWD was sintered well at 1200$^{\circ}C from material surface observation by SEM.

• Journal of Microbiology
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• v.37 no.2
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• pp.66-72
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• 1999

Mycolic acid-containing actinomycetes associated with extensive foaming in the aeration basin of the activated sludge process were isolated and analyzed by phenotypical, chemotaxonomical and phylogenetic methods. Whole cell sugar patterns of two isolates were pattern A. The nearly complete sequences of the 16S rRNA genes (rDNAs) of the isolates were determined and compared by using several tree-making algorithms. With polyphasic methods, strain SCNU1 was identified as Gordona sputi, and strain SCNU5 assigned to the genus Tsukamurella. The presence of opportunistic pathogens of chronic lung infections within foams can cause public health problems and render waste-treatment processes inefficient.

• Journal of the Korean Ceramic Society
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• v.55 no.1
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• pp.36-43
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• 2018

The physical and chemical analyses of mineral waste such as moisture content, water absorption, freezing-thawing resisting sexual, chemical composition and crystal structure were investigated. In the technological process of crushing, screening, molding, drying, preheating, sintering and cooling, many parameters were changed to eliminate the influence of freeze thaw stability and the ball billets were processed into slate ceramsites eventually. Adopting orthogonal experiment and range analysis, the optimal technology parameters were confirmed as preheating temperature of $300^{\circ}C$ for 25 minutes and sintering temperature of $1230^{\circ}C$ for 20 minutes. Slate wastes in Shangri-la could foam and expand without any additive. The ultra-light ceramsite could be directly used as building aggregate, since the analysis results of its leaching toxicity were eligible. Besides, effects of sintering temperature on physical property and crystal phase were also explored in this study.

• Mycobiology
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• v.47 no.1
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• pp.97-104
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• 2019

Mushroom cultivation has gained increased attention in recent years. Currently, only four types of spawn, including sawdust spawn, grain spawn, liquid spawn, and stick spawn, are commonly available for mushroom cultivation. This limited spawn diversity has led to difficulty in selecting suitable inoculum materials in some cultivation. In this study, three small blocks of lignocellulosic agro-wastes and one block of a synthetic matrix were prepared as support for growing Pleurotus ostreatus in liquid medium. Mycelium-adsorbed blocks were then evaluated for their potential as block spawn for fructification. Our results indicated that the edible fungus was adsorbed and abundantly grew internally and externally on loofah sponge and synthetic polyurethane foam (PUF) supports and also has the ability to attach and grow on the surface of sugarcane bagasse and corncob supports. The mycelia of P. ostreatus adhered on corncob exhibited the highest metabolic activity, while those on the PUF showed the least activity. Mycelial extension rates of block spawns made of agro-waste materials were comparable to that of sawdust spawn, but the block spawn of PUF showed a significantly lower rate. No significant differences in cropping time and yield were observed among cultivations between experimental block spawns and sawdust spawns. Moreover, the corncob block spawn maintained its fruiting potential during an examined period of 6-month storage. The developed block spawn could be practically applied in mushroom cultivation.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.63-70
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• 2012

This study was conducted to investigated the distribution, ecological character and life cycle of Black Soldier Fly(BSF), Hermetia illucens, to determine effects of BSF on composing ability to the livestock feces. The distribution of BSF was defined in all parts of the country in Korea. Its main habitat was found to be areas near cattle sheds, feces sheds, living waste dump grounds, and food waste dump grounds. Excellent species of the bio-conversion using the livestock feces were selected out of two kinds of solider flies(Hermetia illucens and Ptecticus tenebrifer). And effects of BSF on composing ability to the livestock feces were pig feces 0.5 g, cattle feces 0.43 g and chicken feces 0.3 g per a larvae of BSF. In the examination of the ability of BSF to decompose food waste, volume of the livestock feces decreased by weight pig feces 77, cattle feces 83.62 and chicken feces 80%. Observed characteristics of BSF larvae and pupae stage were by developmental stage may be summarized as follows: size and length of larvae and pupae of BSF were higher than in pig feces and mixed sawdust treatments. In order to develop artificial indoor rearing techniques, The pupation and emergence rate were not visible the difference but important factor of the mating and egg-laying was a sun light. And it was visible the difference in mating ratio. Mating rate of H. illucens by seasonal change was the highest from May to July. Mating mostly occurred between 10 : 00 and 12 : 00 during which light intensity is high. As the egg-laying medium for artificial egg collection, calf feed and food waste were most effective. The ratio of egg-laying medium is waste food : sawdust(1 : 1) in volume. For egg-laying materials, flower foam and wood with holes were used; holes sized 3 ~ 5 mm in diameter, 7 ~ 10 mm in depth were most preferred for egg-laying.