• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.149-158
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• 2017

Permeating injection is commonly known as an ideal type of injection in grouting reservoir embankment, yet often-combined permeating and fracturing injection grouting operation can disturb the original soil. A grouting method has been regarded as effective and developed to ameliorate the possible disturbance problem. It involves compaction grouting with low expansive pressure near the injection hole and repetitive injection and compaction with grout material that allows ideal permeating injection. This thesis develops Hybrid Grout (ie. HG grout) that allows various application in any ground condition combined together, has high fineness and low viscosity, and expands permeation injection to silty sand. It researches on the injection effect of permeable compaction grout which is done with PC packer and is a combination of HG grout and expansion agent to obtain permeation compaction effect on the area near grout injection spot by developing Permeable Compaction Type Packer(ie. PC packer). As the developed PC packer, HG grout, and and expansion agent (HI-E) are applied to reservoir embankment reinforcement grouting, possibile permeation compaction effect that satisfies reservoir embankment grouting standard is confirmed according to the research.

• Polymer(Korea)
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• v.35 no.3
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• pp.189-195
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• 2011

The design of new bioactive scaffolds offering physiologic environment for tissue formation is an important frontier in biomaterials research. In this study, we performed compressive strength, water-uptake ability, and SEM analysis for physical property assessment of 3-D silk/PLGA scaffold, and investigated the adhesion, proliferation, phenotype maintenance, and inflammatory responses of RAW 264.7 and NIH/3T3 for cell compatibility. Scaffolds were prepared by the solvent casting/salt leaching method and their compressive strength and water-uptake ability were excellent at 20 wt% silk content. Result of cell compatibility assay showed that inflammatory responses distinctly decreased, and initial adhesion and proliferation were maximized at 20 wt% silk content. In conclusion, we suggest that silk/PLGA scaffolds may be useful to tissue engineering applications.

• Polymer(Korea)
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• v.32 no.5
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• pp.403-408
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• 2008

Keratin is the major structural fibrous protein providing outer covering such as wool, hair, and nail. Keratin is useful as natural protein. We developed the keratin loaded poly(L-lactide-co-glycolide) (PLGA) scaffolds (keratin/PLGA) for the possibility of the application of the tissue engineering using bone marrow mesenchymal (BMSCs). Keratin/PLGA (contents 0%, 10%, 20% and 50% of PLGA weight) scaffolds were prepared by solvent casting/salt leaching method. We characterized porosity, wettability, and water uptake ability, DSC of keratin/PLGA scaffold. We seeded BMSCs isolated from the femurs of rat into the inner core of the hybrid scaffold. Celluar viability were assayed by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl-tetrazolium bromide (MTT) test. We confirmed that keratin/PLGA scaffold is hydrophilic by wettability, and water uptake ability measurement results. In MTT assay results, cell viability in scaffolds impregnated 10 and 20 wt% of keratin were higher than other scaffolds. In conclusion, we suggest that keratin/PLGA scaffold may be useful to tissue engineering using BMSCs.

• Composites Research
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• v.32 no.1
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• pp.37-44
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• 2019

The reinforcement effect of micro-bolt for a bonded scarf joint was investigated. Three scarf ratios of 1/10, 1/20, and 1/30 were considered to examine the effect of scarf patch configuration on joint strength. To maintain the same density of micro-bolt, 16, 32, and 48 bolts were installed in the scarf joint specimens with scarf ratios of 1/10, 1/20, and 1/30, respectively. Tests were also carried out on the joints that are bonded with only adhesive and that are fastened with only micro-bolts to obtain reference values. The average failure loads of the adhesive joints with scarf ratios of 1/10, 1/20, and 1/30 were 29.7, 39.6, and 44.8 kN, respectively. In case of micro-bolt reinforcement, the failure loads at the same scarf ratios were 28.4, 37.2, and 40.1 kN, respectively, which corresponds to 96, 94, and 90% of the pure adhesive joint failure loads. In the case of using only micro-bolts, the failure loads were only 13-25% of the average failure loads of pure adhesive joints. Fatigue test was also conducted for the joints with scarf ratio of 1/10. The results show that the fatigue strength of hybrid joints using both adhesive and microbolts together slightly increased compared to the fatigue strength of adhesive joint, but the rate of increase was small to 2-3%. Through this study, it was confirmed that the reinforcement effect of micro-bolt is negligible in the scarf joints where shear stress is dominating the failure, unlike in the structure where peel stress is dominant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.310-316
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• 2021

Conventional satellites are generally large satellites that are multi-functional and have high performance. However, small satellites have been gradually drawing attention since the recent development of lightweight and integrated electric, electronic, and optical technologies. As the size and weight of a satellite decrease, the barrier to satellite development is becoming lower due to the cost of manufacture and cheaper launch. However, solar panels are essential for the power supply of satellites but have limitations in miniaturization and weight reduction because they require a large surface area to be efficiently exposed to sunlight. Space solar cells must be manufactured in consideration of various space environments such as spacecraft and environments with solar thermal temperatures. It is necessary to study structural materials for lightweight and high-efficiency solar cells by applying an unfolding mechanism that optimizes the surface-to-volume ratio. Currently, most products are developed and operated as solar cell panels for space applications with a triple-junction structure of InGaP/GaAs/Ge materials for high efficiency. Furthermore, multi-layered junctions have been studied for ultra-high-efficiency solar cells. Flexible thin-film solar cells and organic-inorganic hybrid solar cells are advantageous for material weight reduction and are attracting attention as next-generation solar cells for small satellites.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.661-669
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• 2022

The need for miniaturization, high efficiency, and green energy resources as an energy storage device through the development of various electronic device has emerged. Accordingly, nanomaterials with excellent electrochemical properties, such as graphene and graphene hybrids, are attracting attention as promising materials. In particular, in the electric vehicle industry, cost reduction of secondary batteries is a key factor that can determine the spread of related industries, and it is most important to analyze R&D trends for battery material technology and respond to future technological development directions. Therefore, in this study, we tried to suggest a direction for R&D activities in the future by analyzing patent trends for graphene anode material technology for secondary batteries and deriving implications. As a result, in the case of anode material technology, the proportion of foreigners in the US and European patent markets was higher than in the Korean and Japanese patent markets, which means that the US and European marketability is high. In addition, Japanese applicants are filing high-level applications not only in the Japanese patent market but also in other countries suggests that Japan is leading the technology in this field. Lastly, the proportion of research institutes in the patent market of Korea and the US remains high compared to that of Japan and Europe, indicating that the commercialization of technology is still slow in those countries. Therefore research institutes and companies in Korea will have to establish their own strategies for developing and securing materials using the results of patent trends in major countries and major companies analyzed in this study.

• Composites Research
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• v.37 no.3
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• pp.170-178
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• 2024

This study proposes a hybrid composite where a thin copper film (Cu film) is embedded in carbon fiber reinforced plastic (CFRP), and quantum annealing is applied to derive the combination of Cu film placement that maximizes the through-thickness thermal conductivity. The correlation between each ply of CFRP and the Cu film is analyzed through finite element analysis, and based on the results, a combination optimization problem is formulated. A formalization process is conducted to embed the defined problem into quantum annealing, resulting in the formulation of objective functions and constraints regarding the quantity of Cu films that can be inserted into each ply of CFRP. The formulated equations are programmed using Ocean SDK (Software Development Kit) and Leap to be embedded into D-Wave quantum annealer. Through the quantum annealing process, the optimal arrangement of Cu films that satisfies the maximum through-thickness thermal conductivity is determined. The resulting arrangements exhibit simpler patterns as the quantity of insertable Cu films decreases, while more intricate arrangements are observed as the quantity increases. The optimal combinations generated according to the quantity of Cu film placement illustrate the inherent thermal conductivity pathways in the thickness direction, indicating that the transverse placement freedom of the Cu film can significantly affect the results of through-thickness thermal conductivity.

• Polymer(Korea)
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• v.32 no.2
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• pp.109-115
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• 2008

Because demineralized bone particle (DBP) contains various bioactive molecules such as cytokines, it is widely used biomaterials in the field of tissue engineering. In this study, we investigated the effect of 2-dimensional DBP/PLGA hybrid films on adhesion, proliferation and phenotype maintenance of intervertebral disc cells. PLGA films incorporated with different amount (0, 10, 20, 40 and 80 wt%) of DBP were prepared by the solvent evaporation method and characterized by scanning election microscopy (SEM). PLGA film has a flat and smooth surface. According to the increase of content of DBP, the surface of DBP/PLGA film exhibited few agglomerates and increased the roughness of the surface. Annulus fibrosus (AF) and nucleus pulposus (NP) cells were cultured on PLGA and DBP/PLGA film surface, and then examined the cell adhesion and proliferation by the cell count and SEM observation. The result of cell count and SEM observation revealed that 10 and 20% DBP in DBP/PLGA films were superior to adhesion and proliferation of both AF and NP cells. We confirmed that specific gene expression of disc cells on DBP/PLGA film based on the cell count result. Disc cells seeded on 20% DBP/PLGA film expressed the gene of type I and II collagen continuously. Therefore, pertinent content of biomaterials could provide more appropriate condition on adhesion and proliferation of cell. And this results may be used as a basic data for the intervertebral disc regeneration using tissue engineering.