• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.5-11
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• 2021

The compacted bentonite buffer is one of the most important components in an engineered barrier system (EBS) to dispose of high-level radioactive waste (HLW) produced by nuclear power generation. The compacted bentonite buffer has a crucial role in protecting the disposal canister against the external impact and penetration of groundwater, so it has to satisfy the thermal-hydraulic-mechanical requirements. Even though there have been various researches on the investigation of thermal-hydraulic properties, few studies have been conducted to evaluate mechanical properties for the compacted bentonite buffer. For this reason, this paper conducted a series of unconfined compression tests and obtained mechanical properties such as unconfined compressive strength, elastic modulus, and void ratio of Korean compacted bentonite specimens with different water content and dry density values. The unconfined compressive strength and elastic modulus increased, and the Poisson's ratio decreased a little with increasing dry density. It showed that unconfined compressive strength and elastic modulus were proportional to dry density. However, there was not a remarkable correlation between mechanical properties and water content.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.5-12
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• 2011

Water content is one of the significant engineering properties of soil for predicting the behavior of soil matrix. Conventional drying oven can be widely used to obtain the values by drying the soil specimens for 16 to 24 hours at $105^{\circ}C$. Although a number of experimental data has been accumulated for the conventional method of drying soil for water contents, shortcomings of the method are still hard to overcome such as long drying time for in situ use and the difficulty of taking prompt actions against emergency cases. Recently, ASTM and JGS have established microwave oven drying techniques for obtaining water contents to cope with those problems. And the reliability evaluation study has been also performed on the microwave oven drying for water contents. Feasibility study of the microwave oven drying was performed to confirm the process of the technique with Jumunjin sand, kaolinite, bentonite, weathered granite soil, and organic soil. Investigation was also conducted on the factors affecting and enhancing the reliability of the technique.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.950-957
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• 2023

Purpose: The response technology is needed to prevent the spill of highly toxic oil contaminants in advance. Therefore, this paper described the results of an experimental study to predict the engineering properties of the developed reactive material. Method: Compaction tests and spectral information acquisition experiments were conducted on the reactive materials, and the results were evaluated. In addition, the correlation between spectral information and maximum dry unit weight was analyzed to evaluate the possibility of predicting the engineering properties for reactive materials. Result: The compaction test results showed that the maximum dry unit weight was in the range of approximately 9kN/m³ to 10kN/m³. The spectral information confirmed that the maximum reflectance decreased as the polynorbornene decreased. Conclusion: It was confirmed that the maximum dry unit weight of the reactive material for absorbing oil contaminants can be predicted using the maximum reflectance according to the component ratio of the reactive material.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.4
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• pp.281-286
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• 2007

Surface sowing method is one of the important methods to establish seeds in mountainous area. Seed-coating technique in the surface sowing method is increasing interest in the world today. An experiment was conducted to develope a technique for pelleting seeds of grass in woodland. Results showed that the seed pelleting was a useful technique than coating seeds because the pelleting reduced coating time and increased amounts of coated seeds per hour. As lowering temperature and reducing time for drying, germinating energy and germination rate of pelleted seeds were improved. And emergence, establishment and early growth of pelleted were also improved in pasture under woodland. Based on this study, we could conclude that the seed pelleting is a useful technique for the establishment and early growth of grass under woodland.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.305-312
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• 2021

This study examines the damage to the submarine's escape trunk hatch spring through microstructure analysis. The cause of the escape trunk's damage during the submarine's construction and its improvement measures were reviewed. To determine the cause of breakage of the escape trunk spring, samples were taken from the damaged product and analyzed for chemical composition, hardness, and microstructure. In particular, the breakage part of the spring was analyzed in-depth by using a scanning electron microscope to determine the cause of corrosion destruction. Finally, a spring shape design method was proposed through the investigation of the cause of spring breakage. In addition, a newly improved spring was produced by applying a nylon coating with excellent corrosion resistance and abrasion resistance. Applying to an actual submarine trunk hatch revealed that the coating peeling phenomenon due to the contact between the springs is significantly improved when the hatch is opened or closed compared to the existing products.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.81-86
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• 2011

The aqueous solution of Sunset Yellow-FCF (SY-FCF) began to show schlieren texture at room temperature when its concentration reaches 25 wt%. A further increase of the concentration of SY-FCF to 28 wt% resulted in a perfect nematic liquid crystal phase. However, more than 30 wt% of SY-FCF in aqueous solution was required to make an optically anisotropic film simply by shear coating. In our study, concentration of SY-FCF solution, coating speed, drying temperature, and relative humidity were considered as coating parameters affecting the preparation of optically anisotropic thin films. From analysis of variance analysis (ANOVA), the solution concentration was revealed as a main factor affecting the film thickness. The drying temperature and solution concentration were main factors affecting the transmittance of parallel direction ($T_o$). Especially, SY-FCF aqueous solution with high concentration induced a better alignment of LC columns and produced highly oriented anisotropic films. In this study, optically anisotropic films prepared by 33 wt% of SY-FCF in aqueous solution showed 89.7~98.7% of degree of polarization.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.209-213
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• 2011

Hydrophobic silica aerogel beads with low thermal conductivity and high porosity were prepared using a cost-effective sodium silicate as a silica source via an ambient-pressure drying process. Monolithic wet gels were first prepared by adjusting pH (~5) of a diluted sodium silicate solution. The silica aerogel beads (0.5~20 mm) were manufactured by breaking the wet gel monoliths under a simultaneous solvent exchange/surface modification process and an ambient-pressure drying process without using co-precursors or templates. Dried silica aerogel beads exhibit a comparable porosity ($593m^2/g$ of surface area, 34.9 nm of pore size, and $4.4cm^3/g$ of pore volume) to that of the aerogel powder prepared in the same conditions. Thermal conductivity of the silica aerogel beads (19.8 mW/mK at $20^{\circ}C$) is also identical to the aerogel powder.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.38-48
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• 2020

In order to inspect the existing or newly constructed ship's hull, a professional diver directly inspects the ship's bottom of the water. However, since it is a work done by people, there are many dangers such as human casualties and crashes. To solve this problem, it is necessary to develop underwater drones for ship inspection for visual inspection. The technology applied to underwater drones, the use and manufacturing process of each component, and the method of manufacture such as firmware development were described, and the difference was compared by measuring the drone's own driving ability and driving ability using crawler under water, and the location tracking device test confirmed the error from the actual location. It is estimated that the use of underwater drones produced through this research will prevent human casualties and achieve economic effects and stability.

• The Hankook-Saengyark Bo
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• no.247
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• pp.5-5
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• 2001

고품질 작약 가공기술 연구(10분 기계박피후 절단 열풍건조, 약효성분 높아) - 자생 둥글레 분재용 개발 - 작약재배때 이랑 30cm로 높여 생육양호하고 경제성도 뛰어나 - $\ulcorner$귀하의 건강 금산 인삼 약초차가 지켜드립니다$\lrcorner$ - 현대화 재배시설 이용 고품질 인삼생력재배

• Bulletin of the Society of Naval Architects of Korea
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• v.41 no.2
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• pp.35-46
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• 2004

조선기자재산업은 선박에 탑재되는 주기관을 포함한 450∼500종의 제품을 공급하는 산업이며, 신조선박의 건조비 가운데 60∼70% 이상을 차지하는 여러 가지 산업(기계, 금속, 전기, 전자, 화학, IT 등)이 관련되는 복합 산업이라 할 수 있다. 조선기자재는 기관시스템, 선체시스템 및 전기시스템으로 분류하며, 부문별 품목의 분류는 표1.1에 보이는 바와 같으며, 각각의 부품의 특성은 아래와 같다.(중략)