• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.156-161
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• 2020

Recently, as there has been growing demand for aesthetic quality in structural materials, the development of excellent color cement concrete having good coloration properties has become a requirement. This study is designed to analyze the basic physical properties of mortar and the properties of keeping the coloration under an ultraviolet ray accelerated weathering test environment according to changes in the mixing ratio between carbon black and iron oxide used as colorants. The test results show that the use of carbon black and iron oxide reduces the initial flow by 6.3~17.2 % and the air content by 3.5~31.5 % but increases the unit volume weight by 3.4~5.5 %, compared to ordinary Portland cement (OPC). In addition, the study shows that the addition of iron oxide increases the self drying shrinkage. So, caution needs to be taken on the workability of the concrete. The brightness value L^⁎ represented by black showed the most excellent black colour when carbon black 3 % and iron oxide 5 % are added. According to UV accelerated weatherproof test, the brightness value L^⁎ was found to increase in all experiment specimens by 4.28~11.97 %, and the color change by UV was found to be higher for the case where carbon black colorant was not used. Therefore, in terms of color revelation characteristics, the case using carbon black 3 % and iron oxide 5 % was found to show the best black color.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.115-122
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• 2018

In this paper, the feasibility of recycling concrete waste as a method to reduce final disposal amount of wastes generated through decommissioning of nuclear power plant has been analyzed based on experimental results of existing literature. When recycled concrete waste was used as recycled aggregate, it was investigated through literature that the concrete strength decreased by 30~40% depending on the mixing ratio. It was also investigated that concrete with recycled aggregate can be used as a structural material when the quality of recycled aggregate is well managed since no significant problem was found. When recycled cement produced from concrete waste was used, the strength of concrete or mortar decreased considerably as the recycled cement content increased. Therefore, it can be concluded that concrete or mortar with recycled cement can be used as a filling material for final disposal of large radioactive waste rather than for structural use. This paper is expected to be useful for reduction on disposal volume and decommissioning cost for nuclear power plants such as Kori 1.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.45-50
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• 2011

In this study, the influence of mixed starter compositions using Saccharomyces cerevisiae and three mixed probiotics, including Bifidobacterium longum, Enterococcus faecium, and Lactobacillus acidophilus on sourdough and bread preparation was examined. The following probiotic and yeast mixing ratios were used: Exp. 1, probiotics:yeast=2.0:0.1; Exp. 2, 1.5:0.1; Exp. 3, 1.0:0.1 (g/g). Starters for the sourdough preparation were incubated separately for 15 hr, combined, then further incubated for 10 hr. Exp 2 resulted in an increase in the numbers of probiotics and yeast in sourdough by 100 times but reduced pH. This is also reflected by the extent of the acidity increase in sourdough produced in Exp. 2. Among the three groups, bread volume and crumb elongation increased in Exp. 2, but crumb fineness and aroma compounds were not significantly different. In a sensory evaluation, flavor, taste, and overall acceptance for the sourdough produced in Exp. 2 improved markedly.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.510-515
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• 2020

In recent years, there has been an increasing interest in research on gluten-free bread. Most studies have focused on substituting or imitating the gluten network. However, less attention has been paid to technological approaches to improve the quality of gluten-free rice bread (GFRB). This study analyzed the influence of the temperature of water used for kneading and fermentation time on the quality of GFRB. Water at various amounts and different temperatures was added for kneading, and fermentation was performed for 0, 2, and 4 h. GFRB produced by kneading using water at 95℃ showed the highest specific volume and the lowest hardness among test groups, regardless of other factors. In conclusion, mixing equal volumes of water at 95℃ and rice flour, followed by a 2 h fermentation process, produced the best-quality GFRB in terms of cross-sectional area, hardness, and appearance.

• Fire Science and Engineering
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• v.26 no.5
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• pp.73-78
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• 2012

This research is to evaluate the fire extinguishing performance of Compressed Air Foam System and this test was conducted using Foam Head System. Compressed Air Foam System adopt the methods of causing the foam by mixing compressed air in foam-aqueous solution, In Overseas, CAFS (Compressed Air Foam System) is generally used because long distance discharge is possible and the water damage can be minimized by reducing the water usage. In this study, Comparative analysis on fire extinguishing effect is done through test to compare the performance between Foam System applied existing air mixture method and Compressed Air Foam System applied AFFF 3 %, foam-extinguishing-agent based on UL162 standard. In Compressed Air Foam System, the volume proportion of air mixture to foam-aqueous solution is 1 to 1 and discharging flow rate is 140 L/min, 160 L/min, 180 L/min, 200 L/min each. As a result of the test, in terms of fire extinguishing performance, fire suppression time for Compressed Air Foam Systems is shorter than for General Air Mixture System in all flow conditions.

• Korean Journal of Environmental Agriculture
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• v.24 no.4
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• pp.386-390
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• 2005

This study was conducted to develop the biofilter fur reducing ammonia $(NH_3)$ and hydrogen sulfide $(H_2S)$ gas emission from a pig house. A biofilter was designed and constructed by a type of squeeze air into the column type of air flow upward. Its column size was ${\Phi}260{\times}360mm$. It was used pressure drop gauge, turbo blower, air temperature, velocity sensor and control program that was programed by LabWindows CVI 5.5. Mixing materials were consisted with composted pine tree bark and perlite with 7:3 ratio (volume). The biofilter media inoculated with ammonia (Rhodococcus equi A3) and hydrogen sulfide (Alcaligenes sp. S5-5.2) oxidizing microorganisms was installed in a commercial pig house to analyzed the effectiveness of biogas removal for 10 days. Removal rates of ammonia and hydrogen sulfide gases were 90.8% and 81.5%, respectively. This result suggests that the pine compost-perlite mixture biofilter is effective and economic for reducing ammonia ana hydrogen sulfide gases.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.192-199
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• 1991

To manufacture a good organic fertilizer through rapid composting process, cow dung was mixed with bulking materials such as rice straws, shredded bark, wood chips, and saw dust. The mixing ratio of the cow dung and bulking material was two to one on volume basis and moisture content was adjusted to 60 to 70 percent, C/N ratio 25 to 30 and aeration forced with suction during the aerated pile fermentation. Aerated pile was established outdoors and curing pile was in vinylhouse and the experiment was conducted for 3 years from '88 to '90. After pilling, temperature in aerated pile was reached to the maximum level at 7 to 9 days and the temperatures of cow dung + shredded bark, cow dung + wood chips, and cow dung + rice straws were higher than that of cow dung, and cow dung + saw dust. Total carbon, and C/N ratio in aerated pile fermentation period were increased in the middle stage and then they were decreased with the process of days, and nutrient contents in curing pile period had the same tendency as in the aerated pile.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.21-28
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• 2017

The steel-plate concrete(SC) is used in a form of module assembly construction in the outer wall of nuclear-power plant and LNG containment. Since the steel-plate concrete modules are generally manufactured from the plant, the weight of SC has significantly effect on the total construction cost in the aspect of shipment. Therefore, the use of lightweight aggregates concrete(LWAC), which fill the inside of SC module can be a solution. However, the amount of used lightweight aggregates(LWA) is limited in the use of current concrete mixing process due to the concrete quality problems and it also determines the allowable minimum density of LWAC. In this research, the preplaced casting method is applied because of increasing the volume fraction of LWA significantly, which results from the producing process of pre-packing the LWA in the formwork and filling the interstitial voids between LWA using cement paste grout. The density and compressive strength of selected preplaced LWAC were $1,600kg/m^3$ and 30MPa and it was applied for the mock-up specimens of SC panel. It was used for the 3-point bending test for evaluating its structural performance. The results show that the preplaced LWAC can reduce the density of concrete with the adequate mechanical and structural performance.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.106-111
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• 2011

This study was conducted to investigate the effect of the mixture ratio of a soldier fly casts (SFC), compost and cocopeat on the soil physicochemical properties. The mixture ratios of soil amendment were 0%, 3%, 5%, 7% and 10% (V/V) incorporated with sand which met to the USGA particle standard. To analyze the effects of amendments on soil chemical properties, pH and EC were measured. The porosity, capillary porosity, air-filled porosity, bulk density and hydraulic conductivity also measured to analyze the physical properties. Chemical properties were significantly different by mixture ratios of a SFC, compost and cocopeat. Capillary porosity was a factor involved in soil physical properties by blending with a SFC and compost. It was affected on the volume of porosity or hydraulic conductivity. To analyze the correlation of mixture ratio versus to physical characters, the ratios of SFC were significantly different in capillary porosity, air-filled porosity, and hydraulic conductivity. These results indicated that mixing ratios of SFC were affected on soil physicochemical properties such as porosity and hydraulic conductivity of the root zone on the USGA sand green.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.9-16
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• 2002

In the synthesis of water-based polyurethane using self-emulsification process, after being neutralized, polyurethane pre-polymers containing ionic pendant groups are dispersed by simple convective mixing. Preparation of dispersion is followed by chain extension reaction, which is considered as important step for growth of the molecular weight of polyurethane. In this work, pH variations in the aqueous phase were monitored during the chain extension process in the presence of water-soluble diamines. The optimum degree of chain extension and the average particle size in the polyurethane dispersions were examined with varying ionic pendent group contents, type of chain extenders, and feed rate of chain extenders, The initial pH value in the aqueous phase linearly increased and the optimum chain extension point could be obtained from the intersection of two linear lines having different slopes, All average particle sizes before chain extension reaction were almost same, however, the final average particle size increased as feed rates of chain extenders increased, In addition, as the ionic pendant group contents increased, the particle size decreased since the hydrophilicity and hydrodynamic volume increased. As carbon numbers of the chain extenders increased, the final particle size increased significantly. From the results, it was concluded that the chain extension reaction took place among the particles not only in a particle.