• Mycobiology
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• 제44권2호
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• pp.67-78
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• 2016

Rice contaminated with fungal species during storage is not only of poor quality and low economic value, but may also have harmful effects on human and animal health. The predominant fungal species isolated from rice grains during storage belong to the genera Aspergillus and Penicillium. Some of these fungal species produce mycotoxins; they are responsible for adverse health effects in humans and animals, particularly Aspergillus flavus, which produces the extremely carcinogenic aflatoxins. Not surprisingly, there have been numerous attempts to devise safety procedure for the control of such harmful fungi and production of mycotoxins, including aflatoxins. This review provides information about fungal and mycotoxin contamination of stored rice grains, and microbe-based (biological) strategies to control grain fungi and mycotoxins. The latter will include information regarding attempts undertaken for mycotoxin (especially aflatoxin) bio-detoxification and microbial interference with the aflatoxin-biosynthetic pathway in the toxin-producing fungi.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.79-82
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• 2007

Recently, the use of ALC has became increasingly popular. ALC is a unique building material. Because of its cellular nature, it is lightweight, self-insulating, sound and fireproof, as well as insect and mold resistant. Furthermore, ALC is free of VOCs and various fibers associated with wood and glass wool construction. However, ALC have high water absorption, low compressive strength and popout the origin of the low surface strength in its properties. These properties make troubles under construction such as cracking and popout. Thus, this study is to improve the fundamental strength by controls of increasing of admixtures, and grain size. Admixtures make use of metakaolin, silica fume, sodium silicate and sodium hydroxide. From the test result, the ALC using admixture have a good fundamental properties compared with plain specimen. Compressive strength, specific strength and abrasion's ratio were improved depending on increasing admixtures ratio's, and grain size.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제12권3호
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• pp.120-125
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• 2002

Si-wafers for solar cells were cast in a size of $50{\times}46{\times}0.5{\textrm}{mm}^3$ by vacuum casting method. The graphite mold coated by BN powder, which was to prevent the reaction of carbon with the molten silicon, was used. Without coating, the wetting and reaction of Si melt to graphite mold was very severe. In the case of BN coating, SiC was formed in the shape of tiny islands at the surface of Si wafer by the reaction between Si-melt and carbon of the graphite mold on the high temperature. The grain size was about 1 mm. The efficiency of Si solar cell was lower than that of Si solar cell fabricated on commercial single and poly crystalline Si wafer. The reason of low efficiency was discussed.

• Journal of the Korean Ceramic Society
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• 제30권12호
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• pp.1029-1038
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• 1993

The microstructures of aluminas, included of dissolved CaO as $\alpha$-alumina seeded pseudo-boehmite hydrosol was gelled in plaster mold and doped of MgO as dipping of calcines(120$0^{\circ}C$-2h) into Mg-nitrate solution, were compared to the one of which additives are excluded during the gellation. It was formed the boundary layer of 300~350${\mu}{\textrm}{m}$ distance from surface to the inside, containing of approximately 500ppm CaO by dissolved Ca from plaster mold. As the MgO addition to the boundary layer with dissolved CaO, the microstructure of the layer was uniformed and inhibited the grian growth, compared to one of that additives be excluded specimen and of MgO doped-inside region. This result was considered as abnormal grain growth and effect of flat boundary formation be appeared by effects of dissolved CaO, were decreased by MgO co-doping.

• Korean journal of food and cookery science
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• 제31권3호
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• pp.264-279
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• 2015

The principal objective of this study was to evaluate the effects of the addition of sourdough to various grain flours in bread, specifically, in regards to the physicochemical characteristics of bread dough, sensory evaluation, and bread storage. As the incubation time of sourdough increased, the total titratable acidity increased. Viable yeast counts of sourdough increased consistently until the third day, while lactic acid bacteria counts increased until the second day. The weight of breads containing sourdough made with rye flour, strong flour, and Korean wheat flour were higher than that of the control. However, the height, volume, and specific volume of control were higher than those of the groups with sourdough made with various grain flours. The pH of breads containing sourdough was lower than that of the control, while the total titratable acidity and moisture content were higher than those of the control. In analyzing the visible mold colony during the five days of storage at $30^{\circ}C$, mold growth in breads containing sourdough made of Korean wheat flour, barely flour, and rye flour was retarded. In the color measurement, the L values of the control and bread containing sourdough made with barley flour were higher than that of the other groups after five days. The a value of bread containing sourdough made of rye flour was higher, and the b values of breads containing sourdough made of Korean wheat flour, barley flour and rye flour were higher than those of the other groups after five days. The hardness of breads containing sourdough increased as storage time increased, where as breads containing sourdough made of Korean wheat flour, Korean whole wheat flour, and rye flour revealed no significant differences with control group. Sensory evaluation scores in terms of after swallowing, taste, and overall preference of bread containing sourdough made of Korean wheat flour was higher than those of the control group.

• Journal of Korea Foundry Society
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• 제21권1호
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• pp.41-47
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• 2001

Computer simulation of the solidification grain structure was applied to the casting process by using CA-DFDM. The Direct Finite Difference Method (DFDM) for temperature field calculation and latent heat treatment was coupled with Cellular Automaton (CA) method for the grain growth. 2-dimensional simulation of the solidification grain structures and calculation of the concentration fields were carried out and the calculated concentration distributions were compared with exact solution. Castings having complex geometries such as turbine blades were applied for 3-dimensional CA-DFDM. Effects of grain selector and mold extraction speed on the solidification grain structures in the turbine blade were examined.

• Journal of the Korean Society for Precision Engineering
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• 제22권10호
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• pp.39-48
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• 2005

As the industrial development is accelerated, a new machining process and system are keenly required to achieve super precision surface finish. Especially to get ground surface finish fer complicated and narrow inner shape of molds, it is impossible with the existing methods so that a new method is being required to be developed. A new material, called Magic(MAGnetic Intelligent Compounds), is finally made and it is called Magic machining that uses this material. There is a way to make a material as follows, the mixture of magnetic particles, bonding material and particles of abrasive grain should be melt down by proper heat, and then this mixture put in a mold and cool down in magnetic field which has a uniform direction. This new polishing method is spotlighted as an excellent solution to the existing problems. However it hasn't reported any study about the influence of the machining conditions of polishing velocity, amplitude and polishing pressure to the surface roughness yet. This study would examine closely the influence of polishing conditions of the Magic polishing tool to the surface finish to decide the optimum polishing condition and to standardize the Magic polishing work.

• Korean journal of applied entomology
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• 제3권
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• pp.27-30
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• 1964

The effects of the rice weevils(Sitophilus oryzae L.) on naked barley and wheat were studied in connection with the moisture contents and the molds in the grain under the controlled conditions; R.H. $75\%,\; 28^{\circ}C.$ 1. The moisture contents of control grain were decreased $2.07\%$ for naked barley and $1.29\%$ in wheat in four weeks. 2. The moisture contents of naked barley which had been infested with 100 weevils were decreased $0.29\%$ and were increased $0.79\% in the berley infested with 200 weevils at t beginning. In wheat, the moisture contents were decreased by$0.84\%\; and\; 0.13\%$ in respective experimental lots. 3. The moisture contents of grains have close relation with the population densities of the weevils in the grain. 4. The pattern of the change in the moisture content of grain have close relation with the population densities of the weevils in the grain. 5. The number of the mold colonies in the grain increased exponentially with the increase in the population densities of weevils in the grain. 6. The species of the mold found were A. restrictus and A. versicolor, which were the most abundant, and A. candidus was also found, but Ins common.

• Journal of Korea Foundry Society
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• 제22권3호
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• pp.109-113
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• 2002

A good fluidity of high strength Al-alloys is required to cast thin wall castings needed to reduce the weight of cast parts. The fluidity, measured as the length to which the metal flows in a standard channel, is affected by many factors, such as the pouring temperature, solidification type of the alloy, the channel thickness, melt head, mold materials and temperature, coating etc. Therefore the experimentally measured fluidity scatters very much and makes it difficult to estimate the fluidity of a melt with a few measurements. The effect of Ti content and grain refinement on the fluidity of high strength aluminum alloy was investigated with a test casting with 8 thin flow channels to reduce the scattering of the fluidity results. The fluidity of Al-4.8%Cu-0.6%Mn Al-6.2%Zn-1.6%Mg-1.0%Cu and well-known commercial aluminum alloy, A356 was tested. Initial content of Ti was varied from 0 to 0.2wt% and Al-5Ti-B master alloy was added for grain refinement. The flow length varied linearly with superheat. By adding Ti and Al-5Ti-B, the fluidity increased. The grain size decreased by adding grain refiner at the same time. The fluidity depended on the degree of grain refinement. The fluidity of the alloy solidifying in mushy type is improved by grain refinement, because grain refinement increases the solid fraction at the time of flow stoppage.

• Korean Journal of Materials Research
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• 제8권9호
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• pp.819-824
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• 1998

The influence of casting cooling rate during the preparation of ingots on the grain size distribution and the magnetizing ability of $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{V}_{4}\textrm{B}_{8}$ sintered magnets were investigated. Sintered magnets prepared from copper mold which allow a higher cooling rate, show a smaller grain size distribution and god magnetizing ability. The effects of adding bride forming elements, such as Cr, Mn, Nb, and W on the magnetic properties of Nd-Fe-B sintered magnets were also investigated. Both Cr and W addition increase coercivity and the resultant $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{Cr}_{4}\textrm{B}_{9}$ alloy exhibits a similar magnetizing ability in comparison with $\textrm{Nd}_{16}\textrm{Fe}_{72}\textrm{V}_{4}\textrm{B}_{8}$ alloy.