• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.543-548
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• 2008

Solid hydrated by hydro-thermal synthesis reaction is cured two times, the first curing is the steam curing at atmospheric pressure and the second one is a high-pressure steam curing, that is autoclaving. Steam curing is to acquire the proper strength for the resistance of treatment in the first curing process, it was not evaluated properly so far. Because of ignorance about curing, some engineers even think that the dry curing is better than the steam curing. The relation between compressive strength of solid hydrated by hydrothermal synthesis reaction and curing condition are presented in this paper. In order to investigate the effect of curing on the strength properties of specimen, the hydration behavior of solid hydrated by hydro-thermal synthesis reaction has been studied over curing condition using XRD, DT-TGA and porosimeter, SEM analysis technique. The results show that the specimens which are cured with blended method of dry and steam curing appear to have better strength properties than that of dry curing and steam curing. Also, there are significant difference of hydration behavior among curing condition in the solid hydrated by hydro-thermal synthesis reaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.69-74
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• 2018

Large industrial motors require a large area because of the high risk of shutdown accidents and large industrial accidents due to the lowering of the dielectric strength of the armature windings and overheating problems. Therefore, there is a demand for a large-capacity motor that has small size, light weight, and excellent dielectric strength compared with conventional motors. Superconducting motors have advantages of high efficiency and output power, low size, low weight, and improved stability. This results from greatly increasing the magnetic field generation by using superconductive field coils in rotating machines such as generators and motors. It is very important to design and analyze the cooling system to lower the critical temperature of the wires to achieve superconducting performance. In this study, a field loss analysis and low-temperature heat transfer analysis of the cooling system were performed through the conceptual design of a 100-HP high-temperature superconducting synchronous motor. The field loss analysis shows that a uniform pore magnetic flux density appears when high-temperature superconducting wire is used. The low-temperature heat transfer analysis for gaseous neon and liquid neon showed that a flow rate of 1 kg/min of liquid neon is suitable for maintaining low-temperature stability of the high-temperature superconducting wire.

• Resources Recycling
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• v.21 no.5
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• pp.38-43
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• 2012

In this study, analysis of the flow of water in the soil environment was attempted to examine the changing patterns of permeability coefficient, k, presented in Darcy's law depending on soil particle size and the pattern of mixed soil that main factor affecting ground water flow in soil environment. In addition, permeability coefficient patterns depending on changes in water temperature and concentration were measured. As a result, the permeability for the soil particle size and mixing pattern is proportional to the size of the particles, and it was also influenced by the porosity depending on the mixed pattern and stratification. Especially compared with the single particle, mixing different sizes samples showed a lower k than the value of smaller single particles. In addition, permeability of groundwater increased with increasing temperature, also permeability decreased depending on the concentration of ions in groundwater. The results of this study were expected to use as meaningful data for the phenomenon reflects the characteristics of the soil to understand mobility of groundwater in soil environment.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.108-114
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• 2007

This study was conducted to clarify the effects of the different mixing ratios of substrate mixtures based on peat moss and the concentration of nutrient solution on the growth of tomato (Lycopersicon esculentum Mill.) seedlings. Substrates such as peat moss, rice hull, carbonized rice hull, decomposed sawdust, perlite and granular rock wool were mixed and used. The concentration of nutrient solution were adjusted to EC $0.5{\sim}1.5mS/cm$. The volumetric moisture contents became higher as peat moss mixed were much more. Total porosities in all substrate mixtures were over 80%, and pH in substrate mixtures became lower as the volume of peat moss mixed higher. Mixing ratios of substrates suitable for the production of tomato seedlings with the higher quality were peat moss:rice hull:carbonized rice hull:decomposed sawdust:perlite=25:10:25:20:20(v/v). The plant growth was not significant among the different substrate mixtures. However, plant growth such as plant height, leaf area, and total dry weight became significantly increased as EC increasing.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1168-1173
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• 2005

Pilot scale vertical-type membrane bioreactor was operated to examine the effect of $FeCl_3$ injection on the removal of organics, nitrogen and phosphorous, and additionally trans-membrane pressure (TMP) was observed. The membrane type was hollow fiber membrane with pore size of $0.25\;{\mu}m$, and the material was polytetrafluoroethylene (PTFE). The membrane permeate was continuously removed by a pump under a constant flux ($25\;L/m^2/h$). Air back-flushing technique were adopted to reduce fouling. As a result, TMP was increased more slowly than that of the operation without air back-flushing, During long-term operation, approximately 310 days, the injection of $FeCl_3$ was effective not only in removing phosphorous chemically but also in reducing TMP increase. Furthermore, while the average COD and T-N concentration of the effluent without $FeCl_3$ injection was 14.3 mg/L and 6.0 mg/L respectively, that of effluent with $FeCl_3$ was 11.3 mg/L and 6.0 mg/L respectively, which confirmed the effects of $FeCl_3$.

• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.324-328
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• 1998

This study was conducted to evaluate the effect of steam explosion treatment on composting with rice straw and barley straw. The composting was performed under the condition of $25^{\circ}C$, water content 70%, C/N ratio 30, and aeration of 100ml/min. The content of cellulose, lignin, and total carbon of compost were increased by steam explosion. During composting process total nitrogen of the compost from rice straw and steam exploded rice straw increased by $2{\sim}2.5$ percent, whereas that from steam exploded barley straw increased by 1.7 percent. However total nitrogen of compost from barley straw decreased by 0.41 percent. Therefore, barley straw is a kind of difficulty material for composting, but the composting was proceeded easily by steam explosion treatment, compared to raw barley straw.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.305-310
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• 2015

In 2014, the city of Seoul revised the ordinance regarding water-cycle restoration in the Seoul Metropolitan areas by incorporating the 'Low Impact Development (LID)' policy. The new ordinance plan will utilize 630 mm or almost 45 to 50% of annual rainfall until 2050 by means of providing a rainwater management system consisting of infiltration, retention and vegetation. The LID is believed to be the key to achieving the target requirements, specifically in development projects. This research was performed to evaluate the stormwater runoff and pollutant reduction performance of three different LID facilities (water circulation facilities) including an infiltration inlet, bioretention swale, and permeable pavement constructed in Seoul City. Results show that among the water circulation facilities, the permeable pavement achieved the highest runoff reduction as it was able to entirely capture and infiltrate the runoff to the ground. However, in order to attain a long-term performance it is necessary to manage the accumulated sediment and trapped pollutants in the landscape areas through other water circulation techniques such as through soil erosion control. In terms of pollutant reduction capability, the infiltration inlet performed well since it was applied in highly polluted areas. The bioretention facility integrating the physico-chemical and biological mechanisms of soil, microorganisms and plants were able to also achieve a high runoff and pollutant reduction. The water circulation facilities provided not only benefits for water circulation but also various other benefits such as pollutant reduction, ecological restoration, and aesthetic functions.

• Science of Emotion and Sensibility
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• v.13 no.2
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• pp.391-402
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• 2010

In this study, breathable waterproof materials were prepared by electrospinning. Five kinds of electrospun nanofiber web layered systems with different levels of nanofiber web density, as well as different substrates and layer structures were fabricated, and their mechanical properties (tensile, bending, shear, compression, surface, and thickness & weight) were measured by the KES-FB system and compared with those of conventional breathable waterproof fabrics (densely woven fabric, PTFE laminated fabric and PU coated fabric). The KES-FB measurements demonstrate that the lab-scale nanofiber web layered systems are more flexible and fuller than commercial nanofiber web layered systems, which have a more compact structure than the lab-scale nanofiber web layered systems. Densely woven fabrics and lab-scale nanofiber web layered systems showed lower values of tensile linearity (LT), bending stiffness (B), and shear stiffness (G) than those of PU coated and PTFE laminated fabric. These results indicate that they are more flexible and have less resistance to the shearing movement, corresponding to a more pliable material having a better drape, than PU coated fabrics and PTFE laminated fabrics.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.81-88
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• 2001

This experiment was carried out to evaluate the effect of residual food compost application on plant growth and physicochemical properties of soil when residual food compost made from the composting process as part of organic waste recycling was applied in soil as variable rate. The treatments were composed non-fertilizer treatment, control treatment applied with pig compost $20Mg(D.W.)ha^{-1}$, and residual food compost treatments each of applied with 20, 40, 60, $80Mg(D.W.)ha^{-1}$ and were randomized complete block design with three replication. Soil pH after experiment was more increased as more increase application of residual food compost. Other chemical properties of soil including EC were also showed the similar results. The plant growth in treatments applied much of residual food compost at the early growth stage was very damaged and these results were proved at the first growth measurement. Production of the red pepper especially reduced in treatments taken growth demage at the early stage and that of $20Mgha^{-1}$ treatment almost same as control treatment. Bulk density was reduced but porosity was increased according to increase of residual food compost application. Considering the reduction of red pepper production and the demage of growth at the early stage by plenty of salt and water soluble application volume of residual food compost was not permitted over of $30Mgha^{-1}$. Additively, to settle the application volume of residual food compost and to evaluate the plant growth and changes of physicochemical properties of soil, the results taken from continual applying is concluded more important than single application.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.69-76
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• 2016

To produce the primary data for best management of soil nutrient in organically practiced soils, 75 leading organic farms whose paddy fields were certified as organic were selected. Soil samples were collected from the paddy fields before plowing, and then analyzed for the determination of physico-chemical properties. Soil pH, organic matter and available phosphate were analyzed and averaged 6.2, $25.6mg\;kg^{-1}$ and $88.4mg\;kg^{-1}$, respectively. Contrary to the national-scale-surveyed paddy soils including organic and conventional farming, pH was higher, available phosphate was lower in the organically practiced soils, but organic matter was similar. With the increasing cultivation period in organic, soil pH and porosity were also increased, EC, available phosphate, bulk density and soil hardness were lower than those from the national survey. Organic matter, however, was not significantly changed. The bulk density was negatively correlated with the organic matter content for both surface topsoil ($R^2=-0.5424$) and subsoil ($R^2=-0.6429$) (p<0.05). Soil quality is improved in most of soil chemical and physical composition factors excluding organic matter and available phosphate. However, it is necessary to establish the counter measure plan for organic matter management and to develop phosphate-containing materials which can be used as organic agricultural material in the future.