• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.415-420
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• 2017

Insulation systems in Liquefied Natural Gas Carriers (LNGC) are vulnerable to sloshing impact and fatigue loads because of waves. If gas leaks into the primary barrier, the Flexible Secondary Barrier (FSB) prevents the leakage of gas in this system. Fatigue strength of the FSB largely depends on the behavior of composite materials. In this study, a new system is applied to the FSB using aramid fiber to improve the fatigue strength of the secondary barrier, with the intention of replacing conventional E-glass fibers. The manufacturing method involved varying the ratio of the aramid fiber to the E-glass fiber for optimum design of the FSB. The fatigue tests results of the secondary barrier using aramid fiber were superior to that using E-glass fiber. The statistical analysis is performed to obtain the fatigue test results and estimate the probability of failure as well as the design guideline of LNGC secondary barriers.

• Membrane Journal
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• v.18 no.4
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• pp.306-316
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• 2008

The adsorption characteristics of L-tryptophan of PES-BSA affinity membranes prepared by using electro-spinning were investigated. It was found that the fiber diameters could be controlled by the comparisons of fiber diameters prepared by various spinning conditions through FESEM and Image Analyzer. Darcy's permeability constants, mechanical properties and hydrophobic properties were enhanced since micro-fibers increased by increasing the composition ratio of HFB and BSA. The elution capacity of L-tryptophan in borate-DMSO buffer solution was higher than that in tris-HCl buffer solution, while the elution capacity of A 7906 type BSA was higher than A 8022 type BSA. This is due to the characteristics of BSA type, i. e. higher purity and uniform molecular weight and better pH stability of A 7906 type BSA than those of A 8022 type BSA.

• Composites Research
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• v.19 no.1
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• pp.36-42
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• 2006

MWNT(multi-walled carbon nanotube)-filled plain-weave glass/epoxy composites were fabricated and electromagnetic characteristics of the composites were investigated. The observation of the microstructures of the composites revealed that MWNTs are mostly distributed in matrix rich region and the interface between glass fiber yarns in warp and fill direction. The permittivity of the composites, measured in X-band (8.2-12.4 GHz) frequency range, increased with weight fraction of MWNTs and remained almost constant with frequency. The measured permittivity was used to investigate the reflection loss of radar absorbing structures (RAS) composed of MWNT-filled composites according to thickness and a RAS were constructed with 10 dB absorbing bandwidth 4.2 GHz and 3.3 mm in thickness.

• Composites Research
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• v.20 no.5
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• pp.7-12
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• 2007

This paper aims to enhance the efficiency of bone fracture healing with bone plate made of fiber reinforced composite materials. The composite bone plate was designed as the same dimension and shape as the existing stainless steel bone plate. To find out the appropriate stacking sequence of the composite bone plate the variations of strain distributions were calculated using FE analysis when the bone plates were applied to the fracture site. From the analysis result it was found that the composite bone plate whose Young's modulus is lower than that of metal bone plate gave more uniform strain distribution and provided appropriate condition for callus formation and its development.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.165-171
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• 2002

The study on the adsorption, the surface properties and the antibacterial effects of the metal-treated pitch based activated carbon fibers was carried out. From the adsorption studies on the series of metal-treated activated carbon fiber, the specific surface areas of the metal treated activated carbon fiber obtained from BET equation were in the range of 113.2~1574 $m^2$/g for the Ag-ACFs. And that of Cu treated ACF are distributed to 688.2-887.8 $\m^2$/g. And, the specific surface areas of the Ni-treated pitch based ACFs were in the range of 692.6~895.2 $\m^2$/g. From the ${\alpha}_s$- method, 0.06~1.1 cm^3/g of the micropore volumes were obtained from Ag-ACFs. And, 0.1~0.2 cm^3/ and 0.2~0.6 cm^3/g of the micropore volumes were obtained from Cu and Ni-ACFs, respectively. And, from the SEM morphology results, it was observed that the surface of activated carbon fiber are partially blocked and coated by metal after the treatment. Finally, from the antibacterial effects of metal-treated activated carbon fiber against E. coli, the areas of antibacterial effect become larger with the increase in mole ratio of metal treated. And, from the antibacterial effects using Shake flask method against E. coli, the percentage of the effects was 92.5~100 % and the antibacterial effect was increased with the increase in mole concentration of metal treated.

• Economic and Environmental Geology
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• v.47 no.5
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• pp.497-505
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• 2014

This study is for discrimination between asbestiform and non-asbestiform based on size characteristics of tremolite-actinolite fibers in soils from a closed asbestos mine, Jecheon, Chungcheongbuk-do, Korea. Soils and tremolite asbestos rocks were collected from a closed asbestos mine area. The dimensions of fibers with minimum $5{\mu}m$ in length and 3:1 in aspect ratio were measured using transmission electron microscopy (TEM) and compared to the known tremolite populations ranging from asbestiform to non-asbestiform. The geometric means of width of soils, asbestos rocks and National Institute for Standard and Technology (NIST) and Health and Safety Laboratory (HSL) reference samples were $1.2{\mu}m$, $0.3-0.6{\mu}m$, $1.3{\mu}m$ and $0.2{\mu}m$, respectively. The geometric means of aspect ratio of soils, asbestos rocks and NIST and HSL reference samples were 7.3, 13.7-30.1, 7.2 and 37.8, respectively. The population of tremolite-actinolite fibers from soils compared to known asbestiform and non-asbestiform tremolite was lack of thin and high aspect ratio fibers. Upper results suggest that tremolite-actinolite fibers in soils cannot be classified into a commercial grade asbestos. The tremolite-actinolite fibers do not mainly appear to be the result of contamination from distance asbestos sources by wind. For the management and control of asbestos in soils, size distributions of amphiboles should be incorporated into asbestos survey results of soils.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.5
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• pp.801-810
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• 1995

부직포의 기공크기에 대한 특성을 측정하기 위해 이미지 프로세싱을 이용하였다. 아라미드부직포와 그 부직포를 시뮬레이션한 부직포에 대해서 기공의 크기를 대표하는 평균 기공크기와 그 분포를 이미지 분석의 두가지 방법으로, 즉, 형태학적인 방법과 기하학적인 방법을 통해 측정해보았다. 아라미드 부직포, 시뮬레이견 부직포이건 상관 없이 부직포의 밀도가 증가함에 따라 기공의 크기특성, 즉 기공의 면적, 수력반경, 그리고 기공내의 최대 내접원의 반경은 감소하였다. 형태학적인 방법과 기하학적인 방법은 부직포의 종류에 상관없이 기공의 크기를 측정함에 있어서 유의한 차이가 없었다. 이는 부직포내의 섬유의 배열방향이 무작위이기 때문이었다. 실제의 아라미드 부직포와 시뮬레이션 부직포의 기공크기에 대한 특성은 서로 비슷한 양상을 보여주었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.5
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• pp.323-330
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• 2023

The development of an analysis model that reflects the microstructure characteristics of polyvinyl alcohol (PVA) fiber-reinforced cementitious composites, which have a highly complex microstructure, enables synergy between efficient material design and real experiments. PVA fiber orientations are an important factor that influences the mechanical behavior of PVA fiber-reinforced cementitious composites. Owing to the difficulty in distinguishing the gray level value obtained from micro-CT images of PVA fibers from adjacent phases, fiber segmentation is time-consuming work. In this study, a micro-CT test with a voxel size of 0.65 ㎛³ was performed to investigate the three-dimensional distribution of fibers. To segment the fibers and generate training data, histogram, morphology, and gradient-based phase-segmentation methods were used. A U-net model was proposed to segment fibers from micro-CT images of PVA fiber-reinforced cementitious composites. Data augmentation was applied to increase the accuracy of the training, using a total of 1024 images as training data. The performance of the model was evaluated using accuracy, precision, recall, and F1 score. The trained model achieved a high fiber segmentation performance and efficiency, and the approach can be applied to other specimens as well.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.11
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• pp.885-890
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• 2015

Nanomaterials possess unique mechanical, physical, and chemical properties. They are small, and have an ultrahigh surface area, making them suitable for air filter applications. Electrospinning has been recognized as an efficient technique for fabricating polymer nanofibers. In order to determine the optimum manufacturing conditions, the effects of several electrospinning process parameters on the diameter, orientation, and distribution of polyacrylonitrile (PAN) nanofiber are analyzed. To improve interlaminar fracture toughness and suppress delamination in the form of laminated non-woven fibers by using a heat roller, the performances of filter efficiency and pressure drop achieved with PAN nanofiber air filter are evaluated experimentally.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.276-281
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• 2015

Nanostructured $TiO_2-SiO_2$ materials have widely been used as anti-reflecting coating, optical-chemical sensors and catalysts because of their superior optical and thermal properties as well as chemical durability. Web type $SiO_2$ microfibers with nano-crystalline $TiO_2$ were prepared by electrospinning of Ti-PCS mixed solution and oxidation controlled heat-treatment, rather simple than sol-gel process. Nano-crystalline anatase phase were formed for the heat-treatment up to $1200^{\circ}C$ and they were finely dispersed in the amorphous $SiO_2$ matrix.