• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.149-153
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• 1999

During a hemisphere-type compression molding, the wrinkles are caused by complex stress condition. It is very important to clarify the degree of wrinkles in order to have good products. In this paper, the effects of numbers of needling and initial area on the degree of wrinkles are studied. the degree of wrinkle is expressed as nonhomogeneity.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.239-241
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• 1999

Recently, the friction and wear behaviors of UHMWPE, ceramic and metal is being researched actively for the use as an artificial hip-joint. In this study, because of good wear properties of carbon fiber, we made experiments about the friction and wear of carbon fiber reinforced epoxy composite under the lubricative and the dry condition. The possibilities of carbon-carbon composite for the artificial hip joint application was studied from this results.

• Composites Research
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• 제28권4호
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• pp.168-175
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• 2015

탄소섬유 강화 복합재료는 높은 비강도 및 비강성을 가지기 때문에 자동차 산업, 선박, 우주 항공 산업과 같은 다양한 산업 분야에 적용되어 왔으며, 수요가 점차 증가하고 있다. 탄소섬유 강화 복합재료에는 기지재로 주로 에폭시(Epoxy)와 같이 점도가 낮고 젖음 특성이 우수하며 강도가 양호한 열경화성(Thermosetting) 수지가 사용된다. 열경화성 수지는 우수한 물리적 특성을 나타내지만 재사용이 어렵다. 이러한 문제를 해결하기 위하여 재사용이 가능한 탄소섬유 강화 열가소성 수지(Thermoplastic) 복합재료 개발 및 탄소섬유 재사용에 관한 많은 연구들이 진행되고 있다. 본 연구에서는 열분해 방법을 사용하여 탄소섬유/에폭시 복합재료로부터 탄소섬유와 수지를 분리하여 탄소섬유를 재활용하였다. 에폭시의 분해도(Degree of decomposition)는 열중량분석기(TGA)와 시차 주사현미경(SEM)을 통해 확인하였다. 수지로부터 분리해낸 탄소섬유는 절단(Cutting)과 그라인딩(Grinding) 방법을 거쳐 탄소섬유 복합재료 시트(Sheet)를 제조하였다. 재활용 탄소 섬유로 제조된 탄소섬유 시트는 각각 다른 냉각조건에서 결정화 엔탈피(Crystallization enthalpy)와 기계적 특성, 표면과 단면의 형태를 분석하였다.

• 콘크리트학회지
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• 제10권4호
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• pp.101-111
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• 1998

본 논문의 목적은 전단내력이 부족한 R/C보에 CFS(Carbon Fiber Sheets), CFRP(Carbon Fiber Reinforced Plastic), GFRP(Glass Fiber Reinforced Plastics)를 이용해 전단보강을 할 경우에 보의 역학적 거동특성을 규명하기 위한 것이다. 본 논문의 목적을 달성하기 위하여 총 19개의 시험체가 제작되었으며, 실험변수로는 전단스팬비, 보강재료, 보강방법, 보강간격 및 방향을 산정하였다. 본 논문의 실험결과, FRP를 이용해 전단내력이 부족한 R/C보에 보강을 하였을 경우 약 50~70%정도의 보강효과를 나타내었다. 또한 소성이론에 근거한 철근콘크리트보의 전단강도 예측모델을 개발하였고 실험치와의 비교를 통해 개발된 모델의 적합성을 검증하였다.

• 대한토목학회논문집
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• 제9권3호
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• pp.49-56
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• 1989

본(本) 논문(論文)에서는 최근(最近)들어 활발히 전개되고 있는 새로운 건설재료의 개발을 위한 노력의 하나로서 기유(機維)콘크리트의 개발과 그 역학적(力學的) 특성(特性)에 관하여 연구하였다. 이를 위하여 포괄적인 실험연구를 수행하였으며 강섬유의 혼입률과 섬유길이를 주요 실험변수로 하였다. 강섬유콘크리트의 역학적특성을 규명하기 위하여 휨거동, 인장거동 및 압축거동을 조사분석하였다. 실험결과 섬유의 혼입률이 증가함에 따라 강도가 증가하며, 특히 연성(延性)이 크게 증가함을 발견하였다. 강도의 증가율은 인장하중상태에서 제일 크게 나타냈고, 그 다음이 휨하중 상태였으며, 압축상태에서는 강도증가가 제일 적게 나타났다. 이것은 섬유의 효과가 콘크리트의 연장에서 더욱 크게 나타남을 의미하고 있다. 본 연구(硏究)는 강기유(鋼機維)콘크리트의 역학적(力學的) 특성(特性) 규명과 함께 강섬유콘크리트의 이용(利用)과 설계(設計)를 위한 중요한 기초자료를 제시하고 있다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.202-205
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• 2003

Investigated whether fiber orientation situation of fiber reinforcement macromolecule composition board and the fiber inclusion rate are perpendicular and horizontal direction tensile strength and some correlation. Fiber orientation situation of tensile strength of 0 direction of composition board increased changelessly by aeolotropy in isotropy. Tensile strength of 90 direction that is isotropy and tensile strength of 0 direction that is aeolotropy agreed almost. Get into aeolotropy, the reinforcement rate of fiber decreased. When load interacts for width direction of reinforcement.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.154-159
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• 1999

In this paper we present tile results of an experimental investigation on the physical and mechanical properties of carbon fiber grid, polymer mortar, and carbon fiber grid reinforced plain concrete flexural members. In order to repairing and reinforcing damaged and/or deteriorated existing concrete structural members, new materials have been developed and utilized in the construction industries. But the physical and mechanical behaviors of the material are not well understood. To use the material effectively various aspects of the material must be throughly investigated analytically as well as experimentally. In this investigation we found the physical and mechanical properties of carbon fiber grid and polymer mortar which are directly utilized in the repair and reinforcement design of damaged or deteriorated concrete structures. In addition, we also investigate the strengthening effect of carbon fiber grid on the plain concrete flexural test specimens. It was found that the material can be used to repair and strengthen the concrete structures effectively.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.129-137
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• 1999

Reinforced concrete structures using early age concrete were result in the degradation of structural performance due to crack, overload, unexpected vibration and impact load. It demands urgently that reinforced concrete structure using early age concrete should be improved the serviceability and structural performance with the application of new fiber materials. Therefore specimens, designed by the test varibles, such as with or without stirrup and percent of steel fiber incorporated, were constructed and tested to evaluate and develop the structural performance of reinforced steel fiber concrete beam. Based on the test results reported in this study, the following conclusions are made. Specimens, designed by the over 0.75% of steel fiber incorporated, were showed the ductile behavior and failed slowly with flexure and flexure-shear. Comparing with the load-displacement relationship of specimen BSS, designed by the recommendations of the Ministry of Construction and Transportation, reinforced steel fiber concrete beam using early age concrete, over 0.75% of steel fiber incorporated, gets enough load carrying capacity and ductility. Increasing the percent of steel fiber incorporated(0.25~2.0%), the ultimate shear stress of each specimen were increased 12~40% than that of control specimen SSS.

• 대한기계학회논문집A
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• 제25권4호
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• pp.564-573
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• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• Tribology and Lubricants
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• 제22권1호
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• pp.1-7
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• 2006

The sliding friction and wear properties of mineral fiber reinforced composite(MF) and glass fiber reinforced composites(GF) are investigated to clarify their field of use and the role of each fiber in friction material. Friction and wear test reveals that GF composite has better wear resistance even though with low friction coefficient, comparing with MF composite. Glass fiber strengthen effectively the matrix and may absorb friction energy to convert it into the fracture energy of them, as well as its lubricative role. However, mineral fiber in MF composite is too small to strengthen the matrix. Then MF composite are easily plowed and worn out by asperity on counter material. Friction coefficient of MF composite is higher friction coefficient than that of GF composite and varied widely with test.