This study derived a non-linear specific force equation for parabolic open channel flows. In addition, an explicit method is presented for obtaining accurately a solution to the specific force equation. The Newton-Raphson method, which has 2nd-order accuracy, was used to obtain the solution of the derived equation. The initial value of the calculation was obtained from recent research results in the form of a regression equation. The maximum relative error is about 0.33% when the conjugate depth ratio is calculated using the existing regression equation, but it is 0.07% using the results of this study, even in the extreme case where the Froude number is around 1.0. That is, the conjugate depth ratio of the parabolic channel can be calculated accurately and easily by using the explicit method presented in this study.

Silafont-36 alloy is an Al-Si-Mg based alloy widely used in automotive applications. Its mechanical properties can be changed through T5 or T6 heat treatment. In this study, we investigated the influence of T6 heat treatment on the mechanical properties of Silafont-36 alloy prepared by die casting. The standard T6 heat treatment condition is as follows: (1) solution heat treatment for 2 hours in vacuum atmosphere at 510°C and water quenching, and (2) artificial aging treatment for 4 hours at 180°C in vacuum atmosphere and air cooling. Heat treatments were applied based on the above treatment conditions with changes in the solution treatment and artificial aging treatment conditions. Tensile test, hardness test, and microstructure analysis were performed on the heat-treated specimens. As the solution treatment temperature increased, the tensile strength increased. On the other hand, tensile strength decreased with increasing aging temperature and holding time. From a microstructure analysis, it was confirmed that the tensile strength increased with decreasing secondary dendrite arm spacing.

In the field of renewable energy, there is growing interest in wind energy to cope with climate change. Research is needed on small residential facilities or stand-alone small wind turbines for microgrid power generation. This study is for commercialization of a small horizontal wind turbine of a 2,600 mm diameter upwind type and is a thesis for a design and performance check on performance. A blade was designed and flow analysis was performed with ANSYS CFX to verify the performance of the generator. As analysis conditions, numerical analysis was performed on the κ-ε, κ-ω , and SST turbulence models, and the torque for each condition was calculated to determine the output from the wind turbine. From the results of the numerical analysis, the maximum torque was calculated in the order of SST, κ-ω, andκ-εand the output was calculated in the order of SST, κ-ω, and κ-ε. The coefficient of power value was calculated as 0.225 for κ-ε, 0.236 forκ-ω, and 0.240 for SST. From the results of the numerical analysis, it was confirmed that all three conditions provided 700 W class output at a 10 ㎧ wind speed condition.

In order to improve the performance of cement mortar using combined sand of crushed and sea sands, this study analyzed its fundamental properties in accordance with replacement by recycled aggregate powder. The results showed that for binary aggregate with crushed and sea sands in a 6 to 4 ratio, the standard gradation was satisfied with replacement by less than 7.5% of recycled aggregate powder. Furthermore, as the replacement ratio of the recycled aggregate powder was increased, fluidity decreased and air content increased. Meanwhile, with replacement of less than 10% by the recycled aggregate powder, compressive strength increased 10 to 20% under the conditions of this research. Overall, it was determined that by replacement of 2.5% of recycled aggregate powder in binary aggregate with crushed and sea sand with poor gradation, optimum results could be obtained for satisfying the standard gradation and improving the fundamental properties of the cement mortar. It is necessary to evaluate the possibility of applying this result to concrete and actual structures.

This paper studies the priority given to real-time monitoring and tracking of mobile weapons systems, including transporter erector launchers, which are a major danger to the military of the Republic of Korea. Also, it aims to present economic and effective measures for observation of the North Korean military by combining artificial intelligence technology with Cube satellites. A large number of Cube satellites were launched into their target orbit and operated. Then the data collected was used to determine how to enable real-time monitoring and tracking of mobile weapons systems, including transporter erector launchers and mobile weapons, of the North Korean military. Besides, the paper describes the process of identifying in actual satellite imagery the weapons, positions, and bases of the North Korean military and conducting virtual experiments with the “Vance AI” and “Google Cloud Platform” tools.

Spent bean sprouts (SBS) are produced during the cultivation, cleaning, and packaging processes for bean sprouts. They account for 50% of total bean sprout production and cause environmental problems and waste disposal costs. This study was conducted to produce bioactive materials including phenolic compounds and flavonoids from SBS in order to produce value-added materials and reduce waste disposal costs. The optimization of extraction conditions was investigated for selection of solvents and evaluation of the effects of main variables, including solvent concentration, extraction temperature, and extraction time. Among these three variables, ethanol concentration showed the greatest effects on the production of total phenolic compound (TPC) and total flavonoid content (TFC). The optimal extraction condition was found to be 57.2˚C, 78.7 min, and 39.0% ethanol (v/v), which resulted in 28.0 mg GAE/g DM for TPC and 1.52 mg QE/g DM for TFC. The production of high concentrations of phenol compounds and flavonoids from SBS by hot-water extraction proves that SBS can be used in the production of functional food and cosmetics materials.

Antibacterial activity of bamboo (Phyllostachys bambusoides) oil (BO) was investigated for two types of gram-positive, gram-negative, and antibiotic-resistant bacteria to determine the possibility of its use as a preservative. Disc diffusion method and minimum inhibitory concentration (MIC) assay were used for the evaluation of the antibacterial activity. BO showed antibacterial activity for all strains, with relatively better antibacterial activity for Bacillus subtilis, Escherichia coli, and Salmonella typhimurium. The results of the disc diffusion method for these three strains showed widths of 1.5 to 25.9 mm, 16.1 mm, and 32.3 mm, respectively, and minimum inhibitory concentrations of 0.2, 0.4, and 0.2%, respectively. These results suggest that the BO is valuable as a plant-derived antimicrobial resource.

Lichen refers to a group of organisms in which two organisms, an alga and a fungus, live together as a single organism. Algae photosynthesize and supply sugars to fungi, and fungi provide a place to live and inorganic nutrients for the algae. In this study, antioxidant activity, polyphenol content, and flavonoid content were investigated to determine the possibility of using extracts of Ramalina yasudae Rasanen as a hair cosmetic material. DPPH and ABTS radical antioxidant assays were performed and the results showed a range of 50-500 μ g/mL (IC50). In the ABTS assay results for R. yasudae the IC50 values were confirmed to be 399 μg/mL for the water extract, 371 μg/mL for the methanol extract, and 250 μg/mL for the alkali extract. In an MTT assay, the R. yasudae alkali extract showed no cytotoxicity up to a concentration of 500 μg/mL. Accordingly, the R. yasudae extracts have the potential to be useful material for cosmetics and edible food.