• Journal of the Korean Geotechnical Society
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• v.30 no.2
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• pp.65-76
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• 2014

For soil improvement, sand mats or sand compaction piles are often constructed on soft marine clays. In such cases, some amounts of sand and clay are inevitably mixed. Sand or gravel often exists in the weathered soils near the slope surface. This research investigates the effect of mixing sand content on consistency limits and shear strength of clays. Firstly, sand was mixed with kaolinite or bentonite at 0, 9, 17, 23, 29, 33, 50% and then liquid and plastic limits were measured. Both plastic and liquid limits decreased as a sand content increased. The water content of clay-sand mixtures with different sand content increased by 10% or 20% step by step and then their undrained shear strength was measured using a portable vane shear device called Torvane. For all cases, undrained shear strength of clay-sand mixtures decreased rapidly until reaching a certain value. Their state changed from undrained to drained state gradually as the sand content increased, which caused their undrained shear strength to decrease. On the other hand, a series of direct shear tests were also conducted on such clay-sand mixtures to investigate the effect of sand content on cohesion and angle of internal friction. It was found from clay-sand mixtures that their cohesion decreased but angle of internal friction increased as the sand content increased.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.107-116
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• 2017

When drilling operation is being performed, many physical and chemical changes are occurred near wellbore. To handle various changes of well condition and keep drilling process safe, additives of bulk, such as bentonite for increasing density of drilling mud, barite for increasing viscosity of drilling mud, polymer for chemical control, or surfactant, are added into drilling mud through a mud shear mixer. Because the achievement of the required material property through mud mixing system is essential to stabilize drilling system, it is of importance to analyze multi-phase flow during mud mixing process, which is directly related to increase mixing performance of the system and guarantee the safety of the whole drilling system. In this study, a series of liquid-solid flow simulation based on a computational fluid dynamics (CFD) are performed with comparing to solid concentration in experiment by Gilles et al. [2004] to understand the characteristics of liquid-solid mixing in a mud shear mixer. And then, the simulation-based design of shear mixer are carried out to improve mixing performance in a mud handling system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.201-209
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• 2015

Currently, 23 nuclear power plants are in operation at Kori, Uljin, Younggwang and Wolsong site and a reference deep geological disposal system has been developed for the spent fuels generated by them. The reference spent fuel for this disposal system has 4.5wt% of initial enrichment, 55 GWd/MtU of burn-up, and 40 years of cooling time. In this paper, to improve disposal efficiency and economic feasibility, the characteristics of spent fuels from nuclear power plants, such as type and burn-up, were reviewed. A disposal canister concept for shorter length and relatively lower burn-up spent fuels than the reference spent fuels was developed. Based on this canister concept, thermal analyses were carried out and a deep geological disposal concept was proposed. Measures of disposal efficiency such as unit disposal area and disposal density were compared between this disposal system and the reference disposal system. Also, economic feasibility, such as the volume reduction of copper, cast iron, and bentonite, was analyzed and the results of these analyses showed that the disposal system proposed in this paper has an efficiency of at least 20%. These results could be used for establishing spent fuel management policy and designing practical disposal systems for spent fuels.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.180-187
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• 2015

This study was conducted to determine the effects of feeding by-product feed (BF)-based silage on the performance, blood metabolite parameters, and carcass characteristics of Hanwoo steers. The BF-based silage was composed of 50% spent mushroom substrate, 21% recycled poultry bedding, 15% cut ryegrass straw, 10.8% rice bran, 2% molasses, 0.6% bentonite, and 0.6% microbial additive (on a wet basis), and ensiled for over 5 d. Fifteen steers were allocated to three diets during the growing and fattening periods (3.1 and 9.8 months, respectively): a control diet (concentrate mix and free access to rice straw), a 50% BF-based silage diet (control diet+50% of maximum BF-based silage intake), and a 100% BF-based silage diet (the same amount of concentrate mix and ad libitum BF-based silage). The BF-based silage was fed during the growing and fattening periods, and was replaced with larger particles of rice straw during the finishing period. After 19.6 months of the whole period all the steers were slaughtered. Compared with feeding rice straw, feeding BF-based silage tended (p = 0.10) to increase the average daily gain (27%) and feed efficiency (18%) of the growing steers, caused by increased voluntary feed intake. Feeding BF-based silage had little effect on serum constituents, electrolytes, enzymes, or the blood cell profiles of fattening steers, except for low serum Ca and high blood urea concentrations (p<0.05). Feeding BF-based silage did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, it improved good quality grade (1+ and 1++) appearance rates (60% for the control group vs 100% for the BF-based silage-fed groups). In conclusion, cheap BF-based silage could be successfully used as a good quality roughage source for beef cattle.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.84-96
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• 2007

We performed the experiments to manufacture the hydrophobic $200cells/in^2$-zeolite honeycomb using HY-type zeolite of Si/Al ratio of 80 for separating and removing the VOCs emitted from small and medium size-plants by adsorption and to determine the drying method for the honeycomb at $105^{\circ}C$ without cracking, then measured performances of the honeycomb to adsorb the benzene, o-xylene, and MEK and to desorb the benzene and MEK saturated on the honeycomb by the nitrogen gas as the desorption gas. As a results, the good honeycomb was formed and the honeycomb was not cracked when the mixing ratio of the zeolite to bentonite to methyl cellulose to polyvinyl alcohol to glycerine to water is 100 : 8.73 : 2.18 : 4.19 : 1.38 : 126 and dried the honeycomb at $105^{\circ}C$ for 24 hours in the drying oven. The shape of the dried honeycomb was not changed after calcination, and the compressive strengths of the honeycomb after drying and calcination were 6.7 and $0.69kg/cm^2$, respectively. The adsorption efficiencies of the honeycomb for benzene, o-xylene, and MEK were $92{\sim}96%$ at the room temperature. The desorption efficiency at $180^{\circ}C$ was higher than that at $150^{\circ}C\;by\;1.5{\sim}13.8%$ depending on the flow rate of the nitrogen gas, and it was found that desorption efficiency is higher than 85% at $180^{\circ}C$ and 1.0L/min of the nitrogen gas. At $180^{\circ}C$ and 0.2 L/min, the concentration of the benzene and MEK in the used desorption gas are higher than 40,000 and 50,000ppm, respectively, so it be used as the fuel for preheating the desorption gas fed into the column in desorption cycle.

• Korean Journal of Plant Resources
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• v.13 no.1
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• pp.41-47
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• 2000

This study was conducted to evaluate development of seed pellet technique such as pellet polymer search, the shape formation and hardness, the germination and emergence rate of the pellet seeds for labor-saving and reducing production cost in onion(Allium cepa L.) cultivation. The pellet seeds shape formation was good such as kaolin, clay, ash, and gypsum, and clay was good shape formation but surface of pellet seed was cracked during the drying. PG(pearlite + gypsum) as pellet material and PVA as binder were the best among the material in consideration with shape and hardness together. The hardness of the pellet seeds was affected by polymers, the kinds and concentration of binders, and that degree was large at polymer. The high hardness polymers were gypsum and coal ash, but burned lime was the lowest hardness among the pellet material. The germination(GP) and emergence percentage(EP) of pellet seed with PG in vitro were the highest among the material, and that was 93.6, 91.8%, respectively. The EP of pellet seed with PG at 20, $25^{\circ}C$ were 91.3, 92.0%, respectively, The EP of pellet seed were over the 91%, and those did not show difference with field moisture capacity , and that of 5 and 6mm size seed were the highest as 92%, respectively. and other size seeds showed over 90%, too. The EP of pellet seed with PG was decreasing as increasing the sowing depth, and that of at 10mm sowing depth was the highest as 92.7%. The time to 50% emergence of that under 70% field moisture capacity was 158h, and that was delayed at 20h compare to control seed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.151-159
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• 2017

A deep geological disposal at a depth of 500 m in stable host rock is considered to be the safest method with current technologies for disposal of spent fuels classified as high-level radioactive waste. The most important requirement is that the temperature of the bentonite buffer, which is a component of the engineered barrier, should not exceed $100^{\circ}C$. In Korea, the amount of spent fuel generated by nuclear power generation, which accounts for about 30% of the total electricity, is continuously increasing and accumulating. Accordingly, the area required to dispose of it is also increasing. In this study, various duplex disposal concepts were derived for the purpose of improving the disposal efficiency by reducing the disposal area. Based on these concepts, thermal analyses were carried out to confirm whether the critical disposal system requirements were met, and the thermal stability of the disposal system was evaluated by analyzing the results. The results showed that upward 75 m or downward 75 m apart from the reference disposal system location of 500 m depth would qualify for the double layered disposal concept. The results of this study can be applied to the establishment of spent fuel management policy and the design of practical commercial disposal system. Detailed analyses with data of a real disposal site are necessary.

• Ecology and Resilient Infrastructure
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• v.4 no.3
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• pp.180-185
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• 2017

Restoration of min-impacted arable land is often performed through stabilization of trace elements by amendment treatment combined with (clean) soil covering on the surface. Recently, soil loss problem from sloping remediated agricultural lands has risen as an emerging concern. In this study, efficacy of aggregation formation was assessed by single and binary treatments of four potential amendments (bentonite, lime, organic matter, and steel slag) applied on three cover soils having different clay contents (9.4, 14.7, and 21.2% for A, B, and C soils respectively). In results of single treatments, 5% organic matter for A soil and 5% lime for B and C soils were found most effective for the aggregation formation compared to the respective controls (without amendments). Among nine binary treatments, 3% organic matter + 1% lime for A soil and 1% organic matter + 3% lime for both B and C soils led to the highest formation of aggregation (30.4, 25.0, and 36.5% for A, B, and C soils). For a site-application, the soil erodibility difference between the cover soils (0.045, 0.051, and 0.054 for A, B, and C soils, respectively) and the national average of arable land (0.032) was assumed to be compensated by amendment addition, which is equivalent to 29.1% aggregation formation. To achieve the aggregation goal, 5% lime for A and B soils and 3% lime for C soil were best in the consideration of benefit/cost, thereby effectively and economically reducing soil loss from sloping remediation site. Soil alkalinity induced by lime treatment was not considered in this work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.128-135
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• 2018

Currently, vertical closed ground heat exchangers are the most widely utilized geothermal heat pump systems and the major influencing parameters on the performance of ground heat exchangers are the ground thermal conductivity(k) and borehole thermal resistance($R_b$). In this study, the borehole thermal resistance was calculated from the in-situ thermal response test data and the individual effects of design parameters (flow rate, number of pipe, grout composition) on the borehole thermal resistance were analyzed. The grout thermal resistance was also compared with the correlations in the literatures. The borehole thermal resistance of the investigated ground heat exchanger results in 0.1303 W/m.K and the grout thermal resistance (66.6% of borehole thermal resistance) is the most influencing parameter on borehole heat transfer compared to the other design parameters (pipe thermal resistance, 31.5% and convective thermal resistance, 1.9%). In addition, increasing the thermal conductivity of grout by adding silica sand to Bentonite is more effective than the other design improvements, such as an increase in circulating flowrate or number of tubes on enhancing borehole heat transfer.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.63-72
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• 2009

Recently the importance and interest for the microbes has been increased because several important results for the effects of microbes on the radioactive waste disposal have been published continuously. In this study, research status and major results on the various roles and effects of microbes in the radioactive waste disposal have been investigated. We investigated and summarized the roles and major results of microbes in a multi-barrier system consisting of an engineered barrier and a natural barrier which is considered in radioactive waste disposal systems. For the engineered barrier, we discussed about the effects of microbes on the corrosion of a waste container and investigated the survival possibility and roles of microbes in a compacted bentonite buffer. For the natural barrier, the roles of microbes present in groundwaters and rocks were discussed and summarized with major results from natural analogue studies. Furthermore, we investigated and summarized the roles and various interactions processes of microbes and their effects on the radionuclide migration and retardation including recent research status. Therefore, it is expected that the effects and roles of microbes on the radioactive waste disposal can be rigorously evaluated if further researches are carried out for a long-term behavior of the disposal system in the deep geological environments and for the effects of microbes on the radionuclide migration through geological media.