• Korean Journal of Materials Research
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• v.4 no.7
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• pp.817-822
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• 1994

The reinforcing effect of C-shape carbon fiber was investigated as comparing to typical round-shape fiber with similar properties. The results show that C-shape fiber reinforced materials have better in almost all aspects of mechanical properties, or 218% in flexural strength, 223% flexural modulus, 157% interlamina shear strength, 227% impact strength, 184% transverse flexural strength and so on. Also in damping characteristics considerably concerned with fatigue life, friction/wear coefficient of a material, C-CF/EP had about 185% greater. In this research, we present the potential of non-circular fiber reinforcing materials by C-shape carbon fiber.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.357-363
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• 2008

This study investigates the durability of carbon/epoxy composites for use on train car bodies under a salt water spray environment. Salt water solution with 5% NaCl, similar to natural salt water, was used for the salt water environmental tests. The specimens were obtained from a composite panel consisting of an epoxy matrix reinforced with T700 carbon fabric. The specimens were exposed to the salt water environment for up to 12 months. Mechanical tests were performed to obtain tensile properties, flexural properties, and shear properties. Dynamic mechanical analysis was used to measure such thermal properties as storage modulus, loss modulus, and tan $\delta$. Also FT/IR tests were conducted to investigate changes in chemical structure with exposure. The results revealed that fiber-dominated mechanical properties were not affected much by exposure time, but matrix-dominated mechanical properties decreased with increasing exposure time. Storage modulus was not very sensitive to exposure time, but glass transition temperature was affected, slightly decreasing with increasing exposure time. Although the peak intensity of FT/IR curves was affected slightly by exposure time, the peak shape and peak location of FT/IR curves were not noticeably changed. Carbon/epoxy composites used for this study were relatively stable to the salt water environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.553-559
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• 2002

Carbon-fiber which has very small radial dimension makes us difficult to measure it's properties. So in this paper, we suggest a simple method to measure the thermal conductivity of a carbon-fiber's and carbon-fiber-reinforced-plastics(CFRP) laminates. The thermal conductivity of CFRP laminates was measured experimentally at the same time analytically. The experimental model is based on the one-dimensional analysis of fin sample because CFRP laminates has a thin geometric configuration. The analytical model to measure the thermal conductivity of carbon-fiber is expressed by use of mean-field model which is based on Eshelby's elliptical inclusion problem. Therefore the thermal conductivity of angle-ply laminates can be computed by use of effective longitudinal and transverse thermal conductivities of unidirectional composite of the constituents.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.292-299
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• 1993

In this paper the effects of the length of carbon fiber on the wear properties of carboni carbon composites were investigated. Carbon/carbon composites were fabricated by the liquid impregnation method using the resol-type phenolic resin as a matrix precursor and PAN-based, non-surface treated carbon fiber as a reinforcement. The measured values of the friction coefficient of carbon/carbon composites against AlSl 304 stainless steel ranged from 0.2 to 0.3 under the operating condition used in this study. The effect of the length of carbon fiber on the friction coefficient of carbon/carbon composites were not found. But, it was realized that the wear rate of carbon/carbon composites tends to increase, as the length of carbon fiber increases.

• Composites Research
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• v.27 no.1
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• pp.14-18
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• 2014

Carbon Fiber Reinforced Plastic (CFRP) has strong and superb material properties, especially in mechanical and heat-resisting aspects, but the drawback is its high price. In this study, we made a hybrid composite using carbon fiber and basalt fiber, which is expected to attribute to its strong material properties and its financial benefits. We found out that the higher the content of basalt fiber included, the lower the intensity, and carbon's intensity contents of 80% showed the similar intensity level as that of CFRP. Besides it was possible to get a better mechanical properties using the composite that included the mixed fiber, instead of using a composition of separate fibers filed.

• Elastomers and Composites
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• v.48 no.2
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• pp.133-140
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• 2013

Carbon fiber reinforced polymer (CFRP) composites consist of carbon fibers in a polymer matrix. Recently, CFRP composites having high thermal stability and low outgassing are finding their use in high performance materials for aerospace and electronics applications under high temperature and high vacuum conditions. Cyanate ester resin is one of the most suitable matrix resins for this purpose. In this study, proper combination of cyanate ester and catalyst, curing behavior, and cure cycle were determined by chemorheology. Optimum condition was found to be catalyst content of 100 ppm and curing temperature of $150^{\circ}C$. Thermal stability and outgassing of cured resin composition were analyzed and the results showed thermal decomposition temperature of $385^{\circ}C$ and total mass loss of 0.29%. The CFRP prepregs and subsequent composites were fabricated by predetermined resin composition and the cure condition. Tensile moduli of the composites were compared with theoretical models and the results were very consistent.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.58-63
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• 2004

This study is to investigate a fracture characteristics of carbon fiber reinforced plastics (CFRP) under the tensile loading as a function of acoustic emission (AE) according to the frequency analysis (transient mode) and AE source location (location mode). It was found that the fracture mechanism of AE frequency analysis was a useful tool for the estimation of different type of fracture in CFRP, i.e., matrix(epoxy resin) cracking, delamitation and fiber breakage same as AE amplitude distribution.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.283-288
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• 2003

The object of this study is to investigate a fracture characteristics of static tensile test as a function of acoustic emission according to the fiber orientation $\theta=0^{\circ}C$ in carbon/epoxy composites, CFRP. On tensile loading, it was recognized that the fracture characteristics of CFRP in a unidirectional composites. Using the results of the AE analysis(a=2mm), it was found that the amplitude distributions of AE signals corresponding the matrix cracking, fiber debonding or delamination, and fiber breaking are 55~70dB(<200sec), 100dB(200~600sec), and 80dB(>600sec).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.8-13
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• 2020

Carbon fiber-reinforced plastics (CFRPs) are extremely strong and light fiber-reinforced plastics containing carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and rigidity are required, such as in the aerospace, automotive, and ship superstructure industries. In CFRP drilling, the tool performance greatly varies depending on the tool shapes, cutting conditions, and diamond coating. This study developed a new type of tungsten carbide drill with multi-blade edges to evaluate the surface quality of CFRP materials according to the coating thickness of diamond-coated drills. Experiments on tool wear, surface roughness, and burr formation were conducted. The bore exit quality of a 12 mμ -coated drill was better than that of a 6 mμ -coated drill. The superior effects of the 12 mμ -coated drill and the good surface quality of CFRP were also demonstrated.

• Composites Research
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• v.27 no.2
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• pp.52-58
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• 2014

Short fiber reinforced composites manufactured by injection molding have diverse fiber orientations variable with measuring positions even in the same specimen, which is caused by the flow induced fiber orientation. Fiber orientations considerably affect the mechanical and thermal properties of final composite products. In this study, fiber orientation of injection molded carbon fiber reinforced PA6/PPO composite was measured at several points of the specimen by optical microscopy analysis and the corresponding izod impact strength, coefficients of thermal expansion (CTE) were also measured to investigate the influence of local fiber orientation on the mechanical and thermal properties. Izod impact strength where fiber was perpendicular to the direction of crack propagation was higher than where fiber was parallel to the direction, which could be explained be the impact resistance reinforcing mechanism by fiber orientation. CTE was also lower where fiber was parallel to the measurement direction of CTE than where fiber was perpendicular to the direction, which could be also explained by the dimensional stability mechanism by fiber orientation.