• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.5
• /
• pp.61-71
• /
• 2009

This paper presents the results of an experiment comparing the current circular CFT columns and circular CFT columns that were additionally confined by carbon fiber sheets (CFS) under axial loading. The main experimental parameters are the numbers of CFS layers and the diameter-to-thickness ratio. 10 specimens were prepared according to the experimental parameter plans, and axial compression tests were conducted. From the tests, the failure procedure, load-axial deformation curve, maximum axial strength, and deformation capacity of the CFT columns and confined CFT columns were compared. The test results showed that the maximum axial strengths of CFT columns additionally confined by CFS are increased higher than those of the current CFT columns, and that local buckling can be delayed due to the confinement effect of CFS.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.1 s.53
• /
• pp.37-43
• /
• 2007

Experiments for circular unreinforced concrete beams confined by carbon fiber tubes (CFT) made of carbon fiber sheets were performed. Selected test parameter was thickness of carbon fiber tube: 1.5mm (3 layers), 2.0mm (4 layers), 2.5mm (5 layers), and 3.0mm (6 layers). Based on the test results, an equation for estimating moment capacity of the circular beams confined by carbon fiber tubes was proposed. Comparison results showed good agreement up to 2.5mm (5 sheets) of the CFT thickness.

• Composites Research
• /
• v.28 no.3
• /
• pp.94-98
• /
• 2015

This paper reports the effects of nickel film interleaves on the interlaminar shear strength(ILSS) of carbon fiber reinforced epoxy composites(CFRPs). A nickel thin film was deposited onto the prepreg by radio frequency(RF) sputtering at room temperature. The ILSS of the nickel film interleaved hybrid composites was increased compared to that of the composites without interleaves. To understand the mechanism of enhancement of the ILSS, the fracture surface of the tested specimens was examined by scanning electron microscopy(SEM). The metal interleaves were acted as a reinforcement for the matrix rich interface and the shear property of their composites improved by enhancing the resistance to matrix cracking.

• Composites Research
• /
• v.23 no.1
• /
• pp.31-36
• /
• 2010

The improvement of electrical conductivity of carbon-fiber reinforced plastics (CFRP) has been investigated by silver nano-particles coating for the purpose of lightning strike protection. Silver nano-particles in colloid were sprayed on the surface of carbon fibers, which were then impregnated by epoxy resin to form a CFRP specimen. Electrical resistance was measured by contact resistance meter which utilize the principles of the AC 4-terminal method. Electrical resistance value was then converted to electrical conductivity. The coated silver nano-particles on the carbon fibers were verified by SEM and EDS. The electrical conductivity was increased by three times of the ordinary CFRP.

• Analytical Science and Technology
• /
• v.13 no.2
• /
• pp.131-135
• /
• 2000

We studied adsorption isotherm, surface properties and antibacterial activity of Cu treated activated carbon fiber (ACF). The BET surface area of Cu treated ACF are distributed to $688.2-887.8m^2/g$. The adsorption results show that BET surface areas move gradually to lower value with increasing treated Cu mole concentration. Using t-method, the specific micropore volumes and average pore size were obtained. From the SEM study, it is also observed that many of micropores in activated carbon fiber are blocked surface after the treatment. And we also observed that the activity of E. coli in kind of colon bacillus increases gradually to larger range with increasing Cu mole ratio. From these results, we suggest the antibacterial mechanism for metal treated ACF.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.8 no.2
• /
• pp.73-81
• /
• 2004

In this study, experimental research was carried out to improve earthquake-resistant performance for the retrofitting of reinforced concrete beam-column joints using carbon fiber materials in existing reinforced concrete building. Six reinforced concrete beam-column joints were constructed and tested to evaluate the retrofitting effect of test variables, such as the retrofitting materials and retrofitting region(plastic hinge, beam-column joint) under load reversals. Test results show that retrofitting specimen(RPC-CP2, RPC-CR, RJC-CP, RJC-CR), using new materials(carbon fiber plate, carbon fiber rod and carbon fiber sheet), designed by the improvement of earthquake-resistant performance and ductility, attained more load-carrying capacity and stable hysteretic behavior.

• Composites Research
• /
• v.36 no.6
• /
• pp.383-387
• /
• 2023

Carbon fiber-reinforced composites have excellent mechanical properties. However, the fracture toughness is a disadvantage due to brittle failure mode. The fracture toughness can be enhanced using hybridization with large-elongation fibers. In this study, polyamide (aramid) fibers are hybridized with carbon fiber with various stacking sequences. As a result, the Izod impact strength was enhanced by 63% with 25% aramid fiber hybridization. It is also shown that there is an optimal point in laminated composite hybridization, [CF/CAF₂/CF]_s stacking sequence.

• Proceedings of the Korean Fiber Society Conference
• /
• 1998.10a
• /
• pp.512-516
• /
• 1998

탄소재료는 높은 전기전도도 및 기계적 강도, 화학적 안정성, 큰 비표면적(1000~3000$m^2$/g) 등의 특성 때문에 연료전지, 리튬이온 이차전지, 전기 이중층 캐패시터(electric double layer capacitor, EDLC).의 전극 활물질로 주목받고 있다[1]. 탄소섬유는 보통 특성과 전구체 핏치에 따라서 두 가지 종류로 분류된다[2]. 하나는 메조페이스 핏치로부터 제조된 고성능 탄소섬유(HPCF)이다. (중략)

• Magazine of the Korea Concrete Institute
• /
• v.10 no.2
• /
• pp.119-126
• /
• 1998

본 연구는 철근비와 보강판비를 조정한 보강철근비를 변수로 탄소섬유쉬트 접착된 철근콘크리트 보에 대하여 그 변형특성과 강도특성 및 파괴모드를 실험적으로 고찰한 것이다. 철근비와 보강판비가 증가할수록 최대내력은 증가하는 경향을 보이지만 탄소섬유쉬트의 겹수가 증가할수록 철근비 증가의 경우와는 달리 에너지흡수능력이 저하된다. 철근비와 보강판비에 따른 파괴모드를 구분하고 시험결과와 비교, 고찰하였던 바 파괴모드와 연성의 측면에서 보강철근비 е의 한계값을 0.87 max으로 제안하였다．탄소섬유쉬트와 철근콘크리트 보의 합성작용이 철근항복이후까지 유지되어 비선형적인 거동을 보임으로써 구조적거동이 양호하게 나타나는 것으로 입증되었다.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.3
• /
• pp.197-208
• /
• 1998

최근들어 손상된 실구조물의 보강공법들이 적용,발전되어왔다. 가장 보편적으로 사용된공법이 강판과 탄소섬유를 이용한 공법이지만, 이론적인 배경과 적용기술이 아직은 정립되어었지 않은 상태이다. 강판보강의 경우 단부에서의 응력집중이 보강 효과를 결정짓는 가장 중요한 변수이므로, 본 연구에서는 이러한 응력집중을 완화하기 위하여 단부에 보강판과확대판을 부착하여 실험을 하였고, 탄소섬유 보강 실험에서는 다층 시공시 보강량을 조절하여 실험하였다. 실험 결과는 하중-처짐, 항복하중, 최대하중, 보강재의 전단응력의 분포와 보강재의 파괴양상을 분류하여 정리하였다. 실험을 통하여 강판 보강의 경우 본 연구에서 제안된 단부에서의 보강방법이 보강효과가 향상된 것을 확인하였고 탄소섬유 보강시에는 탄소섬유의 보강량을 조절함으로써 경제적인 설계와 시공이 가능한 것으로 나타났다.