• Food Science and Biotechnology
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• 제18권3호
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• pp.579-585
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• 2009

Solid-phase microextraction (SPME) has gained widespread acceptance in sample pretreatment due to its solvent-free and easy-to-operate properties. SPME fibers are considered as a key part of SPME technique, since it primarily determines the extraction performance of the method including sensitivity, selectivity, and reproducibility. Generally speaking, target analyte with different chemical property requires fiber coating that has the best affinity towards it. Due to the lack of varieties of commercial fibers available currently, considerable efforts have been recently made to develop tailor-made fibers to fulfill increasing demands of different analysis. This paper concisely classify some SPME fiber preparation approaches such as sol-gel technology, physical deposition, molecularly imprinted technique, and their respective application in food safety analysis.

• Carbon letters
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• 제3권4호
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• pp.192-197
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• 2002

Microstructure plays an important role in controlling the fracture behaviour of carbon-carbon composites and hence their mechanical properties. In the present study effort was made to understand how the different interfaces (fiber/matrix interactions) influence the development of microstructure of the matrix as well as that of carbon fibers as the heat treatment temperature of the carbon-carbon composites is raised. Three different grades of PAN based carbon fibres were selected to offer different surface characteristics. It is observed that in case of high-strength carbon fiber based carbon-carbon composites, not only the matrix microstructure is different but the texture of carbon fiber changes from isotropic to anisotropic after HTT to $2600^{\circ}C$. However, in case of intermediate and high modulus carbon fiber based carbon-carbon composites, the carbon fiber texture remains nearly isotropic at $2600^{\circ}C$ because of relatively weak fiber-matrix interactions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.23-28
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• 2001

Since the steel fiber used in concrete to improve shear and ductility capacity, a number of laboratory tests have been studied to define shear strengthening effect according steel fiber contents in concrete. This study investigates shear strengthening effect of steel fiber in RC columns according to compression strength of concrete. From the structural performance test, following conclusions can be made; the maximum enhancement of shear strengthening effect can be achieved at about 1.0 %~l.5 % of steel fiber contents in comparison with shear capacity ratio, and ductility capacity slightly improved as steel fiber contents increased.

• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.1-10
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• 2003

Shredded waste newspapers, waste acrylic raw fibers, and urea-formaldehyde (UF) adhesives, at 10% by weight on raw material, were used to produce recycled waste paper-waste acrylic raw fiber composite boards in laboratory scale experiments. The physical and mechanical properties of fire retardant treated recycled waste paper-waste acrylic raw fiber composite boards were examined to investigate the possibility of using the composites as internal finishing materials with specific gravities of 0.8 and 1.0, containing 5, 10, 20, and 30(wt.%) of waste acrylic raw fiber and 10, 15, 20, and 25(wt.%) of fire retardant (inorganic chemical, FR-7^®) using the fabricating method used by commercial fiberboard manufacturers. The bending modulus of rupture increased as board density increased, decreased as waste acrylic raw fiber content increased, and also decreased as the fire retardant content increased. Mechanical properties were a little inferior to medium density fiberboard (MDF) or hardboard (HB), but significantly superior to gypsum board (GB) and insulation board (IB). The incombustibility of the fire retardant treated composite board increased on increasing the fire retardant content. The study shows that there is a possibility that composites made of recycled waste paper and waste acrylic raw fiber can be use as fire retardant internal finishing materials.

• Composites Research
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• 제28권3호
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• pp.112-117
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• 2015

Mechanical properties of nonwoven alfa fiber based reinforced biocomposite were evaluated to assess the possibility of using it as a new material in engineering applications such as orthopedic application. Samples were fabricated by needle punching, thermal bonding and Hydroentanglement, by blending alfa fibers with wool fibers or Polypropylene fibers. The mechanical properties were tested and showed that the nonwoven NW3 (alfa fiber/PP/PLA, with hydroentanglement) is the best. It has a value of stress at break of 1.94 MPa, a strain of 54.2% and a young's module of 7.95 MPa, in a production normal direction. A biocomposite has been made with NW3 mixed with PMMA matrix. The use of nonwoven based alfa fiber in reinforcing the composite material increases its rigidity and the tensile strength; the elongation was found to be 1.53%, the Young's Module of 1.79 GPa and the tensile at break of 15.06 MPa. Results indicated that alfa fibres are of interest for low-cost engineering applications and can compete with glass fibres in orthopedic application.

• 대한치과기공학회지
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• 제31권4호
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• pp.37-43
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• 2009

This study evaluated the effect of concentration of glass fiber reinforcement on the flexural properties of auto and heat polymerized denture base resin. The test specimens($64{\times}10{\times}3.3mm$) were made of auto and heat polymerized resin(Vertex, Dentimax, Netherlands). Glass fiber(ER 270FW, Hankuk Fiber Glass, Korea) were used to reinforce the denture base resin. The 2.6%, 5.3% and 7.9% volume pre-impregnated fiber were located at the bottom of specimen. The test specimens(n=7) of each group were stored in distilled water at $37^{\circ}C$ for 50 hours before test. The flexural strength and modulus were measured by an universal testing machine(Z020, Zwick, Germany) at a crosshead speed of 5 mm/min in a three-point bending mode. The data was analyzed by one-way ANOVA and the Duncan's multiple range test(${\alpha}$=0.05). The difference of auto polymerized resin groups and heat polymerized resin groups were statistically analyzed by t-test(${\alpha}$=0.05). Glass fiber showed significant reinforcing effects on auto and heat polymerized resin. For flexural strength and modulus, auto polymerized resin was the highest in 7.9% volume, while heat polymerized resin was the highest in 5.3% volume. In this study, glass fiber at 7.9% volume ratio showed most effective reinforcing effect on auto polymerized resin and glass fiber at 5.3% volume ratio showed most effective reinforcing effect on heat polymerized resin in terms of flexural strength and flexural modulus.

• 펄프종이기술
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• 제34권2호
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• pp.13-21
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• 2002

A new method for measuring fiber length and fiber coarseness was developed using image analysis technique. Measured fibers were transferred to a glass slide on a filter paper placed on a wire of the laboratory paper machine. After staining the fibers on the slide, mean fiber lengths and coarseness were measured by a commercial image analysis software, named KS400. The resultant data obtained from the image analysis displayed a close correlation with those from FS-200 and also showed excellent reproducibility as well as those from FS-200. The length of synthetic fibers over 10 mm long could be readily measured by this new analysis technique. Finally, a substantial improvement in precision for measuring fiber length and coarseness was made with less operator's effort for a given time.

• 대한치과기공학회지
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• 제39권1호
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• pp.25-33
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• 2017

Purpose: The aim of this study was to evaluate accuracy of glass fiber mesh complete denture of before and after curing. Methods: Edentulous model was selected as the master model. Ten study models were made by Type IV stone. Wax complete dentures were produced by the denture base and artificial teeth. CD and GD groups were measured six measurement distance before curing. The wax complete denture was investment after measurement is completed. Using a heat polymerization resin was injected resin. After injecting the resin it was curing. A complete denture was re-measured after curing. The measured data was verified by paired t-test. Results: Overall CD group was larger the value of the measured length. In the CD group, A-D point was larger. The smallest point was the B-D point. However, there was no statistically significant difference only C-D point(p>0.05). In the GD group, A-B point was larger. but B-D point was the smallest. A-D and B-C statistically points showed significant differences(p<0.05). Conclusion: Glass fiber mesh resin complete denture can be clinically applied to the edentulous patient.

• Structural Engineering and Mechanics
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• 제86권3호
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• pp.325-336
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• 2023

A significant component of many civil constructions such as buildings, reservoirs, bridges, and sports halls, concrete has become increasingly popular due to its versatile properties. Concrete's internal characteristics change due to the use of different types of fibers, including changes in its microstructure, volume, and hole dimensions. Additionally, the type, dimensions, and distribution of fibers in concrete can affect the results of flexural strength tests by affecting its compressive and tensile strength. Due to a lack of information, fiber concrete is a new composite material in the production industry that requires laboratory studies to determine its behavior. This study investigated the bending behavior of multilayer slabs made of concrete reinforced by polyamide-propylene fibers against impact in weight lifting exercises. Results showed that adding fibers to concrete slab samples improved the mechanical properties while replacing them hurt the mechanical properties and failure of polymer fiber-reinforced concrete. On the other hand, adding and replacing fibers increases durability and has a positive effect.

• 전기화학회지
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• 제12권1호
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• pp.68-74
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• 2009

본 연구에서는 탄소성형 분리판의 물리화학적, 전기화학적 특성을 분석하여 수소 및 개미산연료 전지의 성능에 미치는 영향을 알아보았다. 기존 기계가공 탄소분리판과 탄소복합소재 탄소성형 분리판의 접촉저항, 부식특성, 소수성을 비교 평가하였다. 특히, 현재 연구개발 중인 탄소복합소재 성형분리판의 경우 계면접촉저항이 기계가공 분리판보다 1.5배 높게 나타났으며, 내식성 실험에서는 산에 취약하여 분리판 표면이 거칠어지고 결정성이 감소하였다. 연료전지의 성능은 분리판의 계면접촉저항에 크게 영향을 받았으며, 계면저항이 적은 기계가공 분리판이 수소 및 개미산 연료 전지에서 높은 성능을 나타냈다.