• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.803-808
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• 1998

As carbon fiber is a light-weight materials, high tensile strength and durability compared with rebar, the retrofitting method for RC structures using carbon fiber sheet (CFS) must be use widely. In this paper, the tensile strength test for carbon fiber sheet variable of CF's weight and elastic modulus to evaluate the design tensile strength of carbon fiber sheet which is needed for the strengthening design of CFS and the calculation of strengthening effect. As a result, the design tensile strength of CFS can be calculate using the effect coefficient of strengthening(α) of CFS, the average tensile strength of CFS and the standard deviation of CFS(equation 5)

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.399-407
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• 2006

In this study, an electrical conductive carbon fiber was used as a biofilter matrix to electrochemically improve the biofilter function. A bioreactor system was composed of carbon fiber (anode), titanium ring, porcelain ring, inorganic nutrient reservoir, and VOC reservoir. Electric DC power of 1.5 volt was charged to the carbon fiber anode (CFA) to induce the electrochemical oxidation potential on the biofilter matrix, but not to the carbon fiber (CF). We tested the effects of electrochemical oxidation potential charged to the CFA on the biofilm structure, the bacterial growth, and the activity for metabolic oxidation of VOCs to $CO_2$, According to the SEM image, the biofilm structure developed in the CFA appeared to be greatly different from that in the CF. The bacterial growth, VOCs degradation, and metabolic oxidation of VOCs to $CO_2$ in the CFA were more activated than those in the CF. On the basis of these results, we propose that the biofilm structure can be improved, and the bacterial growth and the bacterial oxidation activity of VOCs can be activated by the electrochemical oxidation potential charged to a biofilter matrix.

• Journal of Korea Foundry Society
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• v.12 no.3
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• pp.238-247
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• 1992

A carbon fiber(CF) reinforced Cu-10%Sn alloy matrix composite was successfully fabricated by squeeze casting method employing preheated graphite mold and proper process controlling factors. The matrix solidification microstructure of the Cu-10%Sn/CF composite reveals ${\alpha}-dendrite$ and ${\alpha}+{\delta}$ eutectoid. To compare the squeeze cast Cu-10%Sn/CF compostie with PM route fabricated Cu-graphite composites for electric contact material, mechanical wear and electrical arc wear tests were performed. Mechanical wear rate of the Cu-10%Sn/CF is much lower than that of the Cu-graphite composite. Weight loss with a variation of contact number in electrical arc wear tests shows a similar trend between the squeeze cast Cu-10%Sn/CF and PM Cu-graphite composites.

• Elastomers and Composites
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• v.56 no.2
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• pp.65-71
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• 2021

In recent times, the demand for electronic devices has increased because of advancements in the electronics industry. Consequently, research on shielding against electromagnetic interference (EMI) from electronic devices has also progressed significantly. In particular, research on imparting electrical conductivity to plastic has seen substantial progress. In this study, the effect of hybrid fillers comprising carbon fiber (CF) and carbon nanotubes (CNTs) on the electrical properties of polyamide 66 (PA66) composites was investigated. PA66 composites were prepared using a BUSS Co-Kneader single-screw extruder. EMI shielding effectiveness (SE) increased with the increasing addition of unsized CF (UCF), sized CF (SCF), and CNTs. For the PA66/SCF/CNT hybrid filler composites, EMI SE significantly increased with the increase in SCF content. Finally, the hybrid filler comprising SCF and CNTs may have a synergistic effect on the EMI SE and surface resistivity of PA66/SCF/CNT composites.

• Carbon letters
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• v.19
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• pp.32-39
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• 2016

In this work, we studied the effects of electrochemical oxidation treatments of carbon fibers (CFs) on interfacial adhesion between CF and epoxy resin with various current densities. The surface morphologies and properties of the CFs before and after electrochemical-oxidation-treatment were characterized using field emission scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and single-fiber contact angle. The mechanical interfacial shear strength of the CFs/epoxy matrix composites was investigated by using a micro-bond method. From the results, electrochemical oxidation treatment introduced oxygen functional groups and increased roughness on the fiber surface. The mechanical interfacial adhesion strength also showed higher values than that of an untreated CF-reinforced composite.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.86-95
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• 2019

Recently, the applications of carbon fiber have been broader than ever when it comes to such industrials as automobiles, ships, aerospace, civil engineering and architecture because of their lightweight-ness and high mechanical properties. This study analyzed mechanical properties and flexural behavior of carbon fiber reinforced cement composites(CFRC) with different fiber contents and fiber lengths, and also impact resistance by natural drop test on mortar specimens was compared and examined. In addition, contents of carbon fiber(CF) were varied by 0.5%, 1.0%, 2.0% and 3.0%. Fiber lengths was used for 6 mm and 12 mm, respectively. As a result of the test, the flow value was very disadvantageous in terms of fluidity due to the carbon fiber ball phenomenon, and the unit weight was slightly reduced. In particular, the compressive strength was decreased with increasing carbon fiber contents. On the other hand, the flexural strength was the highest with 12 mm fiber length and 2% fiber content. As the results of the impact resistance test, the specimens of plain mortar takes about 2~3 times to final fracture, while the specimens of CFRC is somewhat different depending on the increase of the fiber contents. However, when the fiber length is 12 mm and the fiber content is 2%, the impact resistance was the highest.

• Carbon letters
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• v.14 no.1
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• pp.22-26
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• 2013

The effects of heat treatment temperature (HTT) of polyacrylonitrile-based carbon fiber (CF) on the mechanical, thermal, and tribological properties of C/C composites were investigated. It was found that HTT (graphitization) of CF affects the thermal conductivity and mechanical and tribological characteristics of C/C composites. Thermal treatment of fibers at temperatures up to $2800^{\circ}C$ led to a decrease of the wear rate and the friction coefficient of C/C composite-based discs from 7.0 to 1.1 ${\mu}m$/stop and from 0.356 to 0.269, respectively. The friction surface morphology and friction mechanism strongly depended on the mechanical properties of the CFs. The relief of the friction surface of composites based on CFs with final graphitization was also modified, compared to that of composites based on initial fibers. This phenomenon could be explained by modification of the abrasive wear resistance of reinforcement fibers and consequently modification of the friction and wearing properties of composites. Correlation of the graphitization temperature with the increased flexural and compressive strength, apparent density, and thermal conductivity of the composites was also demonstrated.

• Composites Research
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• v.26 no.5
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• pp.303-308
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• 2013

Carbon fiber (CF) reinforced polypropylene (PP) compositeis was increased to amount consumed. In this study, recycle of composites by recycle times. CF was containing 20%. Mechanical and interfacial propertis of CF/PP was evaluation for number of recycle time. Mechanical assessment of CF/PP was tension, bending, fatigue tension test and izod test method. Interfacial assessment of CF/PP was wettability test and FE-SEM of fracture surface method. Fiber and matrix was changed to recycle time. The more recycle of CF/PP, the more interfacial bonding was decreased. Because fiber and matrix was damaged to thermal damage. And then reinforced CF was shorter than original shape.

• Korean Journal of Materials Research
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• v.12 no.2
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• pp.135-139
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• 2002

Carbon powders (CP) and carbon fiber (CF) were introduced info glass fiber reinforced plastics (FRP) composites to obtain fracture detection function. The composites were evaluated through the relation between a load-displacement curve and an electrical resistance change curve in three point bending test. CP containing FRP (CP-FRP) has a sensitivity of electrical resistance change at much lower load level than CF containing FRP (CF-FRP). In loading-unloading tests, CP-FRP showed a large amount of residual electrical resistance which enables the estimation of loading hysteresis.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.35-38
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• 2005

Carbon fiber sheets are widely used for strengthening the deteriorated RC structures. However most studies on the strengthening method of RC structures with carbon fiber sheets are concerning static problems. The purpose of this experimental study is to present the basic data on fatigue behaviors of. RC beams strengthened with carbon fiber sheets. The experimental parameters of this study are ; 1) the existence of U-shaped carbon fiber sheets at the ends for anchoring, 2) the number of carbon fiber sheet layers in strengthening the RC beams, 3) the load levels of $60\%\~90\%$ of the static bending moment strength, which is obtained form the static tests. Experimental results are estimated from the relationships of load level, displacement, number of repeated load and released energy. It is concluded that U-shaped carbon fiber sheets for end anchoring is very effective and the beams strengthened with one layer of carbon fiber sheet have longer fatigue life than that with three layers.