• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.423-431
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• 2022

In this paper, the results of Planar Motion Mechanism (PMM) test for a 1/15 scaled model of the MARIN Joubert BB2 submarine is dealt with to derive the maneuvering coefficients for surface condition. For the depth of surface navigation, the top of the sail was exposed 0.46 m above the water surface in the model scale, and it corresponds to 6.9 m in the full scale. The resistance and self-propulsion tests were conducted, and the model's self-propulsion point was obtained for 1.328 m/s, which corresponded to 10 knots in the full scale. The maneuvering tests were performed at the model's self-propulsion point, and the maneuvering coefficients were obtained. Based on the maneuvering coefficients, a turning simulation was performed for starboard 30 degree of stern fins. The straight-line stability and control effectiveness in the horizontal plane were analyzed using the maneuvering coefficients and compared with the appropriate range. For the analysis of the neutral fin angle of the X-type stern fin, the stern fin test with drift angles was carried out. As a result, the flow straightening effect at lower and upper parts of the stern fin was discussed.

• Animal Bioscience
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• v.36 no.2
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• pp.315-321
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• 2023

Objective: The study was conducted to investigate the dephosphorylation of Pseudomonas aeruginosa flagellin (PA FLA) by sweet potato purple acid phosphatase (PAP) and the effect of the enzyme on the flagellin-mediated inflammatory response in the A549 lung epithelial cell line. Methods: The activity of sweet potato PAP on PA FLA was assayed at different pH (4, 5.5, 7, and 7.5) and temperature (25℃, 37℃, and 55℃) conditions. The release of interleukin-8 (IL-8) and the activation of nuclear factor kappa- light-chain-enhancer of activated B cells (NF-κB) in A549 cells exposed to PA FLA treated with or without sweet potato PAP was measured using IL-8 and NF-κB ELISA kits, respectively. The activation of toll-like receptor 5 (TLR5) in TLR5-overexpressing HEK-293 cells exposed to PA FLA treated with or without sweet potato PAP was determined by the secreted alkaline phosphatase-based assay. Results: The dephosphorylation of PA FLA by sweet potato PAP was favorable at pH 4 and 5.5 and highest at 55℃. PA-FLA treated with the enzyme decreased IL-8 release from A549 cells to about 3.5-fold compared to intact PA FLA at 1,000 ng/mL of substrate. Moreover, PA-FLA dephosphorylated by the enzyme repressed the activation of NF-κB in the cells compared to intact PA FLA. The activation of TLR5 by PA-FLA was highest in TLR-overexpressing HEK293 cells at a substrate concentration of 5,000 ng/mL, whereas PA FLA treated with the enzyme strongly repressed the activation of TLR5. Conclusion: Sweet potato PAP has the potential to be a new alternative agent against the increased antibiotic resistance of P. aeruginosa and may be a new conceptual feed additive to control unwanted inflammatory responses caused by bacterial infections in animal husbandry.

• Geomechanics and Engineering
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• v.31 no.5
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• pp.439-452
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• 2022

A forecast of slope behavior during catastrophic events, such as earthquakes is crucial to recognize the risk of slope failure. This paper endeavors to eliminate the significant supposition of predefined slip surfaces in the slope stability analysis, which questions the relevance of simple conventional methods under seismic conditions. To overcome such limitations, a methodology dependent on the slip line hypothesis, which permits an automatic generation of slip surfaces, is embraced to trace the extreme slope face under static and seismic conditions. The effect of earthquakes is considered using the pseudo-static approach. The current outcomes developed from a parametric study endorse a non-linear slope surface as the extreme profile, which is in accordance with the geomorphological aspect of slopes. The proposed methodology is compared with the finite element limit analysis to ensure credibility. Through the design charts obtained from the current investigation, the stability of slopes can be assessed under seismic conditions. It can be observed that the extreme slope profile demands a flat configuration to endure the condition of the limiting equilibrium at a higher level of seismicity. However, a concurrent enhancement in the shear strength of the slope medium suppresses this tendency by offering greater resistance to the seismic inertial forces induced in the medium. Unlike the traditional linear slopes, the extreme slope profiles mostly exhibit a steeper layout over a significant part of the slope height, thus ensuring a more optimized solution to the slope stability problem. Further, the susceptibility of the Longnan slope failure in the Huining-Wudu seismic belt is predicted using the current plasticity approach, which is found to be in close agreement with a case study reported in the literature. Finally, the concept of equivalent single or multi-tiered planar slopes is explored through an example problem, which exhibits the appropriateness of the proposed non-linear slope geometry under actual field conditions.

• Journal of Hydrogen and New Energy
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• v.34 no.1
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• pp.8-16
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• 2023

In this work, we report basic performance test results of a lab-scale three phase alternative current (AC) arc plasma torch system for plasma gas reforming applications. The suggested system primarily consists of three graphite electrodes inclined at 12.5° to the central axis, a 𝞥 150 mm cylindrical gas path and a three phase-60 Hz AC power supply. At air flow rate of 50 Lpm and arc currents of 100-175 A, test results revealed that plasma resistances were decreasing from 1.08 Ω to 0.53 Ω with the increase of plasma power from 9.3 kW to 13.8 kW, causing the decrease of power factor and increase of the line voltages. However, the injected air can be heated quickly up to the temperatures of >1,200℃ when injecting AC arc plasma powers of >10 kW.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.103-113
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• 2023

This study focused on understanding the relationship between the design of a tunnel boring machine disc cutter ring and its rock-breaking efficiency, as well as the applicable conditions of different cutter ring types. The discrete element method was used to establish a numerical model of the rock-breaking process using disc cutters with different ring types to reveal the development of rock damage cracks and variation in cutter penetration load. The calculation results indicate that a sharp-edged (V-shaped) disc cutter penetrates a rock mass to a given depth with the lowest load, resulting in more intermediate cracks and few lateral cracks, which leads to difficulty in crack combination. Furthermore, the poor wear resistance of a conventional V-shaped cutter can lead to an exponential increase in the penetration load after cutter ring wear. In contrast, constant-cross-section (CCS) disc cutters have the highest quantity of crack extensions after penetrating rock, but also require the highest penetration loads. An arch-edged (U-shaped) disc cutter is more moderate than the aforementioned types with sufficient intermediate and lateral crack propagation after cutting into rock under a suitable penetration load. Additionally, we found that the cutter ring wedge angle and edge width heavily influence cutter rock-breaking efficiency and that a disc cutter with a 16 to 22 mm edge width and 20° to 30° wedge angle exhibits high performance. Compared to V-shaped and U-shaped cutters, the CCS cutter is more suitable for soft or medium-strength rocks, where the penetration load is relatively small. Additionally, two typical case studies were selected to verify that replacing a CCS cutter with a U-shaped or optimized V-shaped disc cutter can increase cutting efficiency when encountering hard rocks.

• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.441-448
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• 2023

Brucellosis is a contagious zoonotic disease that infects millions of people annually with hundreds of millions more being exposed. It is caused by Brucella, a highly infectious bacterial species capable of infecting humans with an estimated dose of 10-100 organisms. Sirtuin 1 (SIRT1) has been reported to contribute to prevention of viral diseases as well as a chronic infection caused by Mycobacterium bovis. Here, we investigated the role of SIRT1 in the establishment of Brucella abortus infection in both in vitro and in vivo systems using the reported SIRT1 activators resveratrol (RES), piceatannol (PIC), and ginsenoside Rg3 (Rg3). In RAW264.7 cells, SIRT1 activators did not alter the adherence of Brucella or Salmonella Typhimurium. However, reduced uptake of Brucella was observed in cells treated with PIC and Rg3, and survival of Brucella within the cells was only observed to decrease in cells that were treated with Rg3, while PIC treatment reduced the intracellular survival of Salmonella. SIRT1 treatment in mice via oral route resulted in augmented Brucella resistance for PIC and Rg3, but not RES. PIC treatment favors Th2 immune response despite reduced serum pro-inflammatory cytokine production, while Rg3-treated mice displayed high IL-12 and IFN-γ serum production. Overall, our findings encourage further investigation into the complete mechanisms of action of the different SIRT1 activators used as well as their potential benefit as an effective alternative approach against intracellular and extracellular pathogens.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.288-288
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• 2022

Rice is an important staple in the world. And drought is one of the important constraints that negatively affect yield loss and grain quality of rice. CRISPR/Cas9 is a new breeding strategy that can improve the characteristics of rice quickly and accurately. CRISPR/Cas9 is a novel approach that can reliably harvest rice yields in response to a rapidly changing climate. In addition, there is no externally inserted DNA left in genome-editing rice, and it is receiving attention as being able to take responsibility for future food because its characteristics are continuously improved. In the future, high levels of drought resistant in water-constrained environments will be required, which will reduce yield loss. OsSAP was genome-editing with CRISPR/Cas9 in rice. A different line number was assigned to each panicle, and the generation advanced by applying the ear-to-row method. Genome-editing rice has improved drought resistance in drought conditions. Also, in genome-editing rice, the target sequence was homozygous in the 0 generation, and the coefficient of variation of heading date, number of tiller, and 1,000-grain weight was very small in 2 generation. In the era of rapidly changing climate change, CRISPR/Cas9 presents a new breeding strategy that can rapidly and accurately improve agronomic traits of major food crops as well as rice. CRISPR/Cas9 is applied together with traditional breeding to develop into a new breeding strategy, it is suggested that food can be obtained stably in response to climate change.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.685-692
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• 2024

Currently used heating elements are metal and non-metal heating elements, including various types of heaters, and resistance line heating elements have a problem of decreasing thermal efficiency over time, so to solve this problem, a planar heating element using high-purity carbon materials and oxidation-resistant inorganic compounds was applied. Through the manufacture of planar heating elements using CNT, ruthenium composite materials, and ruthenium oxide, physicochemical performance and capacity were increased, and instantaneous responsiveness was increased. Through thick film technology applicable to various base bodies, fine patterns were formed by the screening method in consideration of the fact that the performance of the heat source depends on the viscosity and pattern shape. The heating element was manufactured by thick film printing technology by mixing ruthenium oxide, CNT, Ag, etc. The characteristics of each paste were analyzed through viscosity measurement, and STS 430 was used as a base. Surface temperature and efficiency were measured by testing heaters manufactured for small wind tunnels and real-vehicle experiments. The surface temperature decreased as the air volume increased, and the optimal system boundary was found to be about 200 mm. Among the currently used heating elements, this paper manufactured a planar heating element using thick film technology to find out the relationship between air volume and temperature, and to study the surface temperature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.57-64
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• 2008

Generally, organic paint on steel towers can guarantee durability in normal condition but occasionally shows its deterioration on the power line tower and electric power facilities, exposed to light(ultra violet) or heat. The objective of this study is to develope the inorganic paint material based on fluid silicic acid for steel electric power facilities. For the purpose, optimal mixture proportion is derived through 6 preliminary test and, additionally physical and durability performance test are carried out for selected specimens. The performances of developed organic paint material is similar to those of organic paint material. If resistance to chemical attack is improved, the developed inorganic paint is evaluated to replace the organic paint and obtain wide application.

• Oncology Letters
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• v.41 no.1
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• pp.711-717
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• 2019

In attempting to identify effective anticancer drugs from natural products that are harmless to humans, we found that the gomisin J from Schisandra chinensis fruit has anticancer activity. Schisandra chinensis fruits are used in traditional herbal medicine and gomisin J is one of their chemical constituents. In the present study, we examined the anticancer activity of gomisin J in MCF7 and MDA-MB-231 breast cancer cell lines and in MCF10A normal cell line, in a time- and concentration-dependent manner. Our data revealed that gomisin J exerted a much stronger cytotoxic effect on MCF7 and MDA-MB-231 cancer cells than on MCF10A normal cells. Gomisin J suppressed the proliferation and decreased the viability of MCF7 and MDA-MB-231 cells at relatively low (<10 ㎍/ml) and high (>30 ㎍/ml) concentrations, respectively. Our data also revealed that gomisin J induced necroptosis, a programmed form of necrosis, as well as apoptosis. Notably, gomisin J predominantly induced necroptosis in MCF7 cells that are known to have high resistance to many pro-apoptotic anticancer drugs, while MDA-MB-231 exhibited a much lower level of necroptosis but instead a higher level of apoptosis. This data indicated the possibility that it may be used as a more effective anticancer drug, especially in apoptosis-resistant malignant cancer cells. In an extended study, gomisin J exhibited a strong cytotoxic effect on all tested various types of 13 cancer cell lines, indicating its potential to be used against a wide range of different types of cancer cells.