• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.16 no.4
• /
• pp.141-148
• /
• 2006

Skull melting method can be a good candidate for growing oxide single crystals with high quality and for mass production because of its low production costs and high yield through recycling of crust. In this study, rutile single crystals were frown by the skull melting method and ingot characteristics with the variation of different growth conditions has been investigated. Conditions for high quality rutile ingot growth were used for producing cold-crucible size of ${\Phi}12cm{\times}H14cm$, capacity of 3000 pF tank condenser, work frequency of 2.84 MHz, melt-dwelling time of 9hrs and growing speed of 2 mm/h.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2004.10a
• /
• pp.36-41
• /
• 2004

Postharvest handling of sweetpotatoes is inevitable procedure for the maintenance, storage, management and utilization of high fresh quality of storage roots. It ranges in degree from simple lifting of roots, carrying them from field to storage house and immediate consumption after cooking, to sophisticated methods of curing, and storage under controlled conditions followed by processing into a high quality food products. Postharvest saleability, quality and nutritional value of roots and the presence or absence in roots of bitter, toxic furanoterpenoid phytoalexins or mycotoxins depends greatly on the degree and types of treatment to which produce is subjected. Climatic and soil conditions before harvest and contamination or attack by microorganisms or insect pests in the field may initiate or enhance subsequent postharvest deterioration. Careless postharvest handling can lead to both quantitative and qualitative losses which may be extremely high in some circumstances. Research has concentrated on the improvement of preharvest conditions to increase yield and lower decrease rates. However, such efforts are wasted unless they go hand in hand with others designed to reduce the high degree of loss associated with careless postharvest handling.

• Journal of the Korean Society for Heat Treatment
• /
• v.27 no.5
• /
• pp.235-241
• /
• 2014

Effects of rolling and cooling conditions on microstructures and mechanical properties of high-deformable pipeline steels were investigated in this study. Six kinds of pipeline steels were fabricated by varying rolling and cooling conditions, and their microstructures were analyzed by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. Tensile and Charpy impact tests were conducted on the steels in order to examine the mechanical properties. The steels rolled in the two-phase region showed better low-temperature toughness than those in the single-phase region due to the larger amount of ferrites having high-angle boundaries, although they have lower strength and absorbed energy. The steel rolled in single-phase and finish-cooled at higher temperature showed a good combination of high strength and good low-temperature toughness as well as excellent deformability of the lowest yield ratio and the highest uniform elongation because of the presence of fine ferrite and a mixture of various low-temperature transformation phases.

• Structural Engineering and Mechanics
• /
• v.60 no.2
• /
• pp.337-350
• /
• 2016

Even though extensive researches have been performed for steam explosion due to their complex mechanisms and inherent uncertainties, establishment of severe accident management guidelines and strategies is one of state-of-the arts in nuclear industry. The goal of this research is primarily to examine effects of vessel failure modes and locations on nuclear facilities under typical steam explosion conditions. Both discrete and integrated models were employed from the viewpoint of structural integrity assessment of steel components and evaluation of the cracking and crushing in reinforced concrete structures. Thereafter, comparison of systematic analysis results was performed; despite the vessel failure modes were dominant, resulting maximum stresses at the all steel components were sufficiently lower than the corresponding yield strengths. Two failure criteria for the reinforced concrete structures such as the limiting failure ratio of concrete and the limiting strains for rebar and liner plate were satisfied under steam explosion conditions. Moreover, stresses of steel components and reinforced concrete structures were reduced with maximum difference of 12% when the integrated model was adopted comparing to those of discrete models.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1329-1334
• /
• 2007

The electrochemical oxidation of cerium(III) was carried out using divided and undivided electrochemical cells in nitric acid medium. It was found that divided cell with Nafion 324 as the separator gave good conversion yield with high current efficiency compared to the undivided cell. The efficiency of the divided electrochemical cell was further optimized in terms of cell voltage, temperature, flow rate of solution recirculation, concentrations of Ce(III) and nitric acid. The better conditions for 1 M Ce(III) in 3 M nitric acid were found to be 2.5 V, 363 K and 100 mL/min recirculation flow rate based on the current efficiency under the experimental conditions investigated. The Ce(IV) oxidant produced was used as a mediator for the mineralization of phenol. The mineralization efficiency of the cerium mediated electrochemical oxidation was found rapid and higher compared to the direct electrochemical oxidation based on CO2 evolution under the same conditions.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.5
• /
• pp.585-591
• /
• 2012

The antagonistic effect of Trichoderma harzianum on a range of seed-borne fungal pathogens of wheat (viz. Fusarium graminearum, Bipolaris sorokiniana, Aspergillus spp., and Penicillium spp.) was assessed. The potential of T. harzianum as a biocontrol agent was tested in vitro and under field conditions. Coculture of the pathogens and Trichoderma under laboratory conditions clearly showed dominance of T. harzianum. Under natural conditions, biocontrol effects were also obtained against the test fungi. One month after sowing, field emergence (plant stand) was increased by 15.93% over that obtained with the control treatment, and seedling infection was reduced significantly. Leaf blight severity was decreased from 22 to 11 at the heading stage, 35 to 31 at the flowering stage, and 86 to 74 at the grain filling stage. At harvest, the number of tillers per plant was increased by 50%, the yield was increased by 31.58%, and the 1,000-seed weight was increased by 21%.

• Fisheries and Aquatic Sciences
• /
• v.11 no.4
• /
• pp.224-228
• /
• 2008

With the aim of increasing the $CoQ_{10}$ production in mass culture, the effect of aeration-agitation on the $CoQ_{10}$ production using Rhodobactor sphaeroides was investigated in a l-L bioreactor. The maximum $CoQ_{10}$ production was 1.69 mg/g of dry cell weight under conditions of 50 Lux, $30^{\circ}C$, 300 rpm, and 5-vvm aeration. The $CoQ_{10}$ production was improved to produce 2.91 mg/g of dry cell weight under reduced conditions of agitation speed (200 rpm) and aeration rate (0.2 vvm). When R. sphaeroides was cultivated under more reduced DO levels during the exponential phase of the cell, the $CoQ_{10}$ production yield of 3.88-mg/g dry cell weight was the maximum obtained. Therefore, poorer conditions of aeration-agitation resulted in higher production of $CoQ_{10}$, and thus DO content was a crucial factor in the production of $CoQ_{10}$. Accordingly, it was necessary to control the DO concentration in order to enhance the $CoQ_{10}$ biosynthesis within a large-scale production.

• Journal of Ginseng Research
• /
• v.34 no.1
• /
• pp.59-67
• /
• 2010

Response surface methodology was used to predict the optimum conditions of explosive puffing process for ginseng. A central composite design was used to monitor the effect of moisture content and puffing pressure on dependent variables such as functional compounds (extract yield, crude saponin, acidic polysaccharide, and total phenolic content) and sensory properties. Correlation coefficients $(R^2)$ of models for crude saponin, acidic polysaccharide, and total phenolic content were 0.9176 (p<0.05), 0.9494 (p<0.05), and 0.9878 (p<0.001), respectively. Functional compounds increased with decreasing moisture content and increasing puffing pressure. Overall palatability was high at 15-20% moisture content and 98-294 kPa of puffing pressure. On the basis of superimposed contour maps for functional compounds and overall palatability of puffed ginseng, the optimum ranges of puffing conditions were 10-17% moisture content and 294-392 kPa puffing pressure.

• Korean Journal of Materials Research
• /
• v.27 no.6
• /
• pp.318-324
• /
• 2017

In this study, two Fe-30Mn-0.2C-(1.5Al) high-manganese steels with different surface conditions were hydrogen-charged under high temperature and pressure; then, tensile testing was performed at room temperature in air. The yield strength of the 30Mn-0.2C specimen increased with decreasing surface roughness(achieved via polishing), but that of the 30Mn-0.2C-1.5Al specimen was hardly affected by the surface conditions. On the other hand, the tendency of hydrogen embrittlement of the two high-manganese steels was not sensitive to hydrogen charging or surface conditions from the standpoints of elongation and fracture behavior. Based on the EBSD analysis results, the small decrease in elongation of the charged specimens for the Fe-30Mn-0.2C-(1.5Al) high-manganese steels was attributed to the enhanced dislocation pile-up around grain boundaries, caused by hydrogen.

• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.323-327
• /
• 2000

Microwave-assisted process (2,450MHz), which is known as a more environmental-friendly process with economic advantages than the current extraction methods, was investigated to pre-establish the extraction conditions for soluble ginseng components used for the processing of ginseng products. The extractions of soluble ginseng components showed optimum conditions, such as 60 mesh in particle size, 1 : 10 (g/mL) in the sample to solvent ratio, and less than 100 watts in energy efficiency. Under these conditions using along with 60% ethanol for 5 min, the overall yield of ginseng extracts was about 83%. Most soluble components including saponins were extracted by repeating five times of microwave-assisted extraction.