• Journal of radiological science and technology
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• v.40 no.1
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• pp.93-99
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• 2017

Dose enhancement effects at megavoltage (MV) X and ${\gamma}-ray$ energies, and the effects of different energy levels on incident energy, dose enhancement agents, and concentrations were analyzed using Monte Carlo simulations. Gold, gadolinium, Iodine, and iron oxide ($Fe_2O_3$) were compared as dose enhancement agents. For incident energy, 4, 6, 10 and 15 MV X-ray spectra produced by a linear accelerator and a Co-60 ${\gamma}-ray$ were used. The dose enhancement factor (DEF) was calculated using an ICRU Slab phantom for concentrations of 7, 18, and 30 mg/g. The DEF was higher at higher concentrations of dose enhancement agents and at lower incident energies. The calculated DEF ranged from 1.035 to 1.079, and dose enhancement effects were highest for iron oxide, followed by iodine, gadolinium, and gold. Thus, this study contributes to improving the therapeutic ratio by delivering larger doses of radiation to tumor volume, and provides data to support further in vivo and in vitro studies.

• Fire Science and Engineering
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• v.22 no.1
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• pp.99-104
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• 2008

It is important to understand thermal characteristic as a method to estimate the new materials, because spontaneous ignition characterized by causing combustion in the low temperature without ignition source. If can not find out the thermal characteristics of materials, it is frequent that causes of fires could not be found. The danger level of spontaneous ignition material should be estimated and by closely studying its thermal characteristic. However, RPF(Refuse Paper & Plastic Fuel) is a solid matter and getting increasesa year by year because it is an economy profit as alternative energy for limited fossil fuels. Some time RPF occur a fire in the cases of its production process and conservation. Therefore study for thermal stability and critical ignition temperature of RPF was so imperative that the experiment by means of Bombe Calorimeter, TG-DTA, MS80, SIT-II, and Wire Basket Test was implemented. As a result, RPF had a caloric value 26.4-28.3 MJ/kg, and its initial pyrolysis temperature was $192^{\circ}C$ at heating rate 2 K/min. With the result of analysis by MS 80 which is an instrument measuring microscopic calory, pure RPF not containing water has higher caloric value than RPF containing 20% water. Also, SIT-II which is an instrument of insulated auto-ignition was ignited by $118.5^{\circ}C$. This temperature is lower than that of Wire Basket Test. The critical ignition temperature was calculated by Frank-Kamenetskii equation can cause ignition at $80^{\circ}C$ when conserved in the height of 10 m by the standard of infinity slab.

• Journal of Mushroom
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• v.12 no.1
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• pp.17-23
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• 2014

pH of oriental medicine sludge was 5.3, which was similar to 5.2 of the main ingredient, corncob. Its sugar content, however, was 4.8 mg/g, which was 2.5 times higher than concorb's 1.9 mg/g. According to the addition content analysis of oriental medicine sludge by using blood agar plate, the experimental group showed much more robust growth than the control group. 10% of oriental medicine sludge was added to corncob and pine tree sawdust for test-tube culture. Then they were cultivated at $25^{\circ}C$ for 6 days after inoculating Flammulina velutipes liquid spawn. The control group and experimental group showed 2.2~3.4 and 5.8~6.4 cm hypae growths respectively. At the field test for 10% herbal medicine refuse, mushroom yield dropped by 5% compared to the control group. However, it had distinctively lower number of deformity and the 2nd grade products. An economic analysis was conducted based on the cultivation facility that produces 160,000 mushrooms per day. The analysis demonstrated that the facility can save 50,000,000 won in the starting year and 130,000,000 won in the following years from the unit cost of production excluding labour and operation cost.

• Journal of the Korean Geosynthetics Society
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• v.8 no.1
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• pp.33-40
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• 2009

The laboratory tests and field plate load test were carried out to evaluate the reinforcement effect of geocell for road construction. The geocell-reinforced subgrade shows the increment of cohesion and friction angle with comparison of non-reinforced subgrade. In addition, the field plate load test was performed on the geocell-reinforced subgrade to estimate the bearing capacity of soil. The direct shear test was conducted with utilizing a large-scale shear box to evaluate the internal soil friction angle with geocell reinforcement. The number of cells in the geocell system is varied to investigate the effect of soil reinforcement. The theoretical bearing capacity of subgrade soil with and without geocell reinforcement was estimated by using the soil internal friction angle. The field plate load tests were also conducted to estimate the bearing capacity with geocell reinforcement. It is found out that the bearing capacity of geocell-reinforced subgrade gives 2 times higher value than that of unreinforced subgrade soil. The settlement and the distribution of deformation were also estimated by using the finite element method. The magnitude of settlements on the geocell-reinforced subgrade and unreinforced subgrade are 6.8cm and 1.2cm, respectively.

• Polymer(Korea)
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• v.38 no.5
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• pp.640-644
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• 2014

As a process of plat panel display production, slot coating is widely used for the coating of photoresist on a wide glass substrate. A uniform coating thickness is important, and the coating uniformity is divided into nozzle and machine directions. The machine and nozzle directions coating uniformities are influenced by the operation condition of coater and flow uniformity inside the die, respectively. Non-uniform coating during steady coating process occurs according to those factors, however, non-uniform coating along the machine and nozzle directions has been observed at the beginning of coating by unsteady flow. In this study, steady and unsteady state flow simulations have been performed and compared with experiment to examine the causes of non-uniform coating. Computational results exhibited that it took a time to get a uniform pressure distribution at whole inside the die, and during this period of time edge regions showed lower exit velocity compared with center region. Subsequently edge regions had thinner coated layers than center region. However edge regions showed higher exit velocity than center region after steady state, and this made edge regions had thicker coated layer than center region.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.308-314
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• 2015

This study was conducted to establish a fluorescence assay system for high efficient mass screening of the herbicides causing rapid membrane peroxidation, based on the fact that peroxide in cellular leakage could be fluorometrically determined through the fuorescent compounds formed after reacting with homovanillic acid (HVA) and peroxidase (HRP). The assay procesure established in this study was as follows. Only single disc (4 mm diameter) excised from cucumber cotyledon is placed on the well containing test solution ($200{\mu}L$) with 96-well microplate. The plate is shaking-incubated for 8 h under light condition. Then after removing the cucumber disc, HVA and HRP are supplied in the medium buffer and incubated for 5 min at room temperature. Fluorescence values are determined at Ex 320 nm/Ex 425 nm. The higher fluorescence values are obtained in the treatment of chemical having higher herbicidal activity. Using this assay with 96-well microplates, a large number of herbicides inducing rapid membrane peroxidation seemed to be screened more efficiently than spectrophotometric microtiter assay reported previously.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.383-390
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• 1992

In the periods of July 31 to August 10. 1988 and March 9 to 13. 1989. sediment samples were collected from the South Sea stations (010] to 092]) located in the area from $N 32^{\circ}$/30' to $34^{\circ}$/30', of latitude and from E $123^{\circ}$ 30' to $128^{\circ}$30' of longitude. These samples were analyzed for the number of total heterotrophic bacteria and extracellular digesting enzyme activities. In the 1989 spring period the number of heterotrophic bacteria in the sediment surface layer was increased more than 100 times at the maximum compared to that in the 1988 summer period. The proportion of fresh water bacteria to total heterotrophic bacteria was also higher in the spring period than the summer period. The extracellular digesting enzyme activities were higher in spring season than summer. Although the water content of sediment in the spring period was lower than that the summer period. the ash weight indicating organic material content was higher. These results means that the diameters of sediment particles were larger in spring than summer but the input of organic material into the sediment was greater. Based on these results bacterial distributions in the sediment layer of South Sea depend greatly on the season due to the effect of fresh water. During the spring season plankton could grow extensively owing to the inorganic nutrients input by the vertical mixing in the water column, then be precipitated into the sediment. Organic nutrients supplied from enzymatic degradation of polymeric particle from plankton can increase the bacterial number, too.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.373-378
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• 2010

Studies on standardization and quality upgrade of nuruk which is a basic component in brewing are required to increase the quality level of Korean traditional rice wines and to develop the technology for practical use of it. It is important to isolate best strains, to improve the properties and effectively preserve them for brewing industry. In this study, 16 commercial nuruk samples were obtained from the commercial markets located in Chungcheong areas in Korea. 174 fungal strains were isolated from the samples on DG18 medium using a dilution plating method and then screened for enzyme activity and acid production. The active strains were identified based on the morphological characteristics and ITS sequence analysis. Out of 174 strains, 12 strains showed high amylase activity. Especially, Rhizopus sp. CN084, CN174, Aspergillus sp. CN161 and Mycocladus sp. CN042 showed high saccharogenic power and dextrinogenic enzyme activity on cooked wheat bran medium. On the other hand, Aspergillus sp. CN010, CN161, Rhizopus sp. CN105, CN168 and Rhizomucor sp. CN088 produced high acid production on the same medium. Our results showed that the active strains may be used as microbial sources for nuruk starter with good quality in brewing.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.779-783
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• 2004

New food ingredient was developed to eradicate and protect against re-infection of Helicobacter pylori in fermentation broth of lactic acid bacteria (LAB) showing antimicrobial activity against pathogenic microorganisms such as H. pylori and Listeria monocytogenes. LAB strain CBT SL4 was identified as Pediococcus pentosaceus by 16S rDNA sequencing and its culture broth showed antimicrobial activity of 800 AU/mL against H. pylori in optimized fermentation process. Using thin layer concentration system and spray-typed fluid bed drier system, concentrated powder product showing activity of 12,800 AU/g was harvested. Product showed eradication and protection activities against H. pylori infection on feeding test (50 AU/day) using Mongolian gerbil infection model. After 4 weeks therapy of 8,000 AU/day, ${\Delta}13CO_2$ level (DOB30) decreased about 40% in urea breath test on patient with H. pylori infection. Result show concentrated culture product of P. pentosaceus CBT SL4 has eradicating and protecting activities against H. pylori infection and can be used as food-active ingredient for prevention of gastric and duodenum ulcer caused by H. pylori.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.407-411
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• 2015

Dense ceramic membranes have been prepared using the commercial perovsikite $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$, powders synthesized by the solid state reaction method. The as-synthesized powders were compressed into disks with 1.0 mm of thickness and the disk was sintered at $1,100^{\circ}C$ for 2 hr. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membrane increased with the increasing temperature and oxygen partial pressure. The activation energy for oxygen permeation was increased with the increasing oxygen partial pressure. Oxygen permeation flux at $950^{\circ}C$ were measured at various flow rates of feed and sweep gas. It has been demonstrated that oxygen permeability increased at elevated flow rates of both gases, but the sweep gas is more influential.