• Environmental Engineering Research
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• v.19 no.1
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• pp.101-105
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• 2014

Three magnesium compounds, $MgO_2$, MgO, and $Mg(OH)_2$, which are supposed to supply oxygen continuously, were applied onto contaminated bay sediment and its ecology in order to activate the local microbial flora. Those compounds were found to reduce chemical oxygen demand (COD), total nitrogen (T-N), and total phosphorus (T-P). Magnesium oxide, in particular, reduced COD by 30% and T-N and T-P considerably. All compounds also suppressed the release of pollutants in the order $MgO_2$, MgO, and $Mg(OH)_2$. Analysis of microbial flora showed that the microbial group treated by $MgO_2$ and $Mg(OH)_2$ was predictably stable; meanwhile, that treated by MgO increased the number of species, but decreased the total number of microorganisms.

• 시스템엔지니어링워크숍
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• s.1
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• pp.65-68
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• 2003

The air separation plants in the POSCO's Gwangyang Steel Works require high standard on quality as well as reliability as they have to continuously supply essential utility gases as oxygen, nitrogen and argon. And the plants are in the category of high pressure gas systems by the regulatory guidelines, which signifies that they have to maintain utmost level of safety. As an effort to systematically understand and calculate the risk potentials in the air separation plants, risk assessments have been performed on a phased approach: qualitative and followed by quantitative POSCO has chosen to use hazard and operability study and fault tree analysis to satisfy the requirement. As a result, the risk assessment team has identified number of safety and operability related findings. With importance of each and ever findings calculated, a priority list for what/when to do for them could have been presented on a balance fashion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.343.2-343
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• 2002

Squeeze film dampers(SFDs) are designed and analyzed for radial superconducting bearings. The designed SFDs are mounted on the superconductors submerged in liquid nitrogen such that the dampers should supply additional damping to the relatively underdamped superconducting bearing support. Basic theory of SFD with superconducting bearing are introduced. Rotordynamic simulations are provided to support the feasibility of the superconducting magnetic bearings mounted on SFDs for a horizontal flywheel energy storage system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.32-37
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• 2000

The in vitro culture of rice panicles is a culturing technique only panicle without other organs in culture solution containing organic substance, so that would be useful to study how assimilate supply affects grain development and maturation. To find the optimum stage for in vitro culture, rice panicles grown in greenhouse were sampled periodically after anthesis and cultured in nutrient medium. The panicles older than 1 weeks after anthesis had produced normal grains. Grain-filling was apparently dependent upon sucrose concentration (8-12 %) in medium, but not affected by nitrogen concentration supplied with glutamine. As far as rice panicle was supplied with sucrose and N in nutrient medium, grains continued accumulation of dry matter and maturation regardless to light condition. Considerably, grain-filling was improved when panicles were positioned horizontally inside flask, so that each grain was partially submerged to nutrient medium.

• Journal of the Korean Society of Tobacco Science
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• v.8 no.2
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• pp.3-8
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• 1986

This study was carried out to investigate the effect of different soil moisture contents on the growth and chemical constituents of burley tobacco and on the protein pattern in tobacco leaf. Height, stem diameter, and largest leaf length of tobacco droughted from 45 to 60 days after transplanting was not recovered by rewatered amount of water supply from 60 to 75 days after transplanting, but leaf width enlarged. Dry weight per unit leaf area and total nitrogen content showed high values in low soil moisture, but total alkaloid contents were not different according to soil moisture contents. Soil moisture content didn't effect on the protein pattern of middle and upper leaves, but lower leaves showed the mild color and fewer numbers of the protein bands than those of midd1e and upper leaves.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.316-323
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• 2004

HTS transformer is one of the most promising devices to supply enough electric energy for quick increase consumption. However, for practical design of the HTS transformer, it is necessary to establish the research on breakdown, V-t characteristics, degradation, and so on. In this paper, we discussed breakdown characteristics and V-t characteristics of polyimide/L$N_2$ and glass fiber reinforced plastic/$LN_2$ composite insulations. These composite insulations have been used as turn-to-turn and layer-to-layer insulations for HTS transformer respectively, Moreover, we investigated the degradation of these insulation samples after breakdown using microscope and SEM photograph.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.189-192
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• 2004

Test Facility for hot firing test of small size liquid rocket engine has been developed to research the cooing characteristics of kerosene for cylinder part especially. Propellants for the tests are kerosene and liquid oxygen as fuel and oxidizer respectively and they are fed by gaseous nitrogen. The engine components used hot firing test except for cylinder are cooled by tap-water. Valves for supply of propellants and coolants are controlled by pneumatically. System control and data recording are conducted automatically.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.54-58
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• 2006

Stirling cryocooler is relatively compact, reliable, commercially available. and uses helium as a working fluid. Over the past decade and a half, there has been rapid development of Stirling cryocooler, mainly for military and space applications. Stirling cryocoolers have been widely used lot the cooling of infrared sensors and high temperature superconducting filters to the temperature of the liquid nitrogen. The Stirling cryocooler with the rotary compressor is applicable to the cooling device for the compact mobile thermal imaging system, because the cryocoolers have the compact structure and light weight. In this paper, integral Stirling cryocooler is designed, manufactured and fabricated, and performance characteristics are investigated. This cooler delivers approximately 0.6W cooling at 80K for 20W of input power from 24V DC power supply.

• Journal of Animal Environmental Science
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• v.16 no.2
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• pp.135-142
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• 2010

The composting of layer manure is economical and efficiently process. In this study, the variation of composting characteristics in layer manure was investigated according to air supply capacity. The fermented compost was added in layer manure and mixed with sawdust inside composting reactors. The level of air supply capacity was varied in the range of $50{\sim}200\;{\ell}/m^3/min$. During composting the temperature variations of composting piles was different the temperatures of composting piles for T-1 ($50\;{\ell}/m^3/min$) and T-2 ($100\;{\ell}/m^3/min$) were reached at $40^{\circ}C$ and $50^{\circ}C$ within 2 days, respectively. For T-3 ($150\;{\ell}/m^3/min$) and T-4 ($200\;{\ell}/m^3/min$), their temperatures was $60^{\circ}C$ within same days and maintained during 8 days. Water contents decreased according to the air supply capacity; 8.9%, 15.4%, 18.0% and 18.6% for T-1, T-2, T-3 and T-4. The weight ratios of T-1, T-2, T-3 and T-4 were reduced to 12.8%, 15.6%, 18.1% and 17.9%, respectively. The decreasing volumetric ratios of T-1, T-2, T-3 and T-4 were 18.0%, 21.0%, 22.3% and 22.0%. The oxygen discharge concentrations during composting were 12 ppm for T-1, T-2 and 9 ppm for T-3 and T-4. After composting, fertilizer components such as total nitrogen (TN) and phosphorous pentoxide ($P_2O_5$) were examined at each air supply capacity. Nitrogen contents of the T-1, T-2, T-3 and T-4 were 0.75%, 0.74%, 0.72% and 0.64%. Also, The contents of $P_2O_5$ were 0.35%, 0.40%, 0.38% and 0.42% for T-1, T-2, T-3 and T-4.

• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.147-153
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• 2017

BACKGROUND: Soil water content strongly depends on weather condition and irrigation, and it could influence on crop nutrient use efficiency. This study was performed to assess nutrient uptake of soybean by soil water condition. METHODS AND RESULTS: In this study, nutrient leaching and crop uptake as affacted by water management practice was investigated using weighing lysimeter which is located in National institute of agricultural science, Wanju, Jeonbuk province from June 2015 to October 2016. Water supply for soybean (cv. Daewon) was managed with irrigation and rainfall. Nitrate leaching was greatest in the rainfall treatment at early July 2016. Yield of soybean in the rainfall treatment was only 25% compared to the irrigation due to the drought at flowering and podding period. The uptake of nitrogen was considerably reduced by drought whereas the uptake of phosphorus and potassium was less affected by drought. CONCLUSION: It was proven that nitrogen loss and uptake were dependent on soil water condition. Therefore, irrigation water management to maintain available soil moisture capacity is critical to nitrogen uptake and yield of soybean.