• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.609-614
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• 1997

Recently, many researchers have performed R&D about strengthening of R/C with steel plates, carbon fiber sheets. aramid fiber sheets and glass fiber sheets, and so on. However most of research were limited in study of flexural strengthening of R/C beams. This paper shows the results of an experimental study on shear reinforcement of deep beams using Glass Fiber Sheet in relation to shear-span ratio. strengthening orientation and anchorage. The results prove that shear failure is governed by reinforced orientation. adherence and anchorage. Additional anchorage of fibers does not only cause the improvement in the internal resistance, but also control the brittle shear failure of specimen after reaching the maximum load.

• 한국구조물진단유지관리공학회 논문집
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• 제11권1호
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• pp.130-140
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• 2007

섬유시트보강 및 강판보강은 RC 구조물에 주로 사용되었으나, 이들은 조기부착파괴나 자중의 과다 등의 단점을 가지고 있어 현실적으로 적용사례가 대폭 줄어들고 있는 실정이다. 본 연구에서는 전단강도 증가를 위해 GSP(Glass fiber-Steel composite Plate)로 전단보강된 RC 보의 실험한 결과를 제시한다. GSP는 높은 강도의 유리섬유시트를 조기탈락하지 않도록 앵커링할 수 있으며, 정착시 섬유시트의 손상을 방지할 수 있도록 얇은 강판을 섬유시트 사이에 둔 보강재료이다. 기준 실험보 3개와 GSP로 전단보강된 보 60개로 전단실험을 수행하였다. 본 연구는 GSP로 전단보강된 RC보의 전단 보강효과를 평가하며, 이 실험결과 GSP로 전단보강된 RC보의 전단강도는 기준실험보에 비하여 현저히 증가하였음을 확인하였다.

• Composites Research
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• 제24권6호
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• pp.31-36
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• 2011

성형조건에 따른 GMT-Sheet를 관찰하여, 성형품 표면의 섬유돌출을 조사했다. 섬유돌출은 모재의 수축에 의해서 성형품 표면에 생성되는 불량현상의 하나이다. 즉, 섬유돌출은 성형온도에서 상온까지 성형품이 냉각될 때 모재와 유리섬유의 수축차에 의해 발생하는 표면불량 현상이다. 성형품 표면의 섬유돌출 높이는 보압 냉각과정에서 성형압력이 클수록 작게 나타남을 알 수 있다. 성형품 표면의 섬유돌출 높이는 성형압력의 영향이 지배적임을 알 수 있다. 성형압력을 고려하여, 성형품의 표면요철 생성과정과 섬유돌출 높이 변화를 규명했다. 그리고 피복층은 표면불량 현상을 억제하는 효과가 있고, 표면으로부터 섬유돌출이나 크랙이 보이지 않았다. 피복층은 표면거칠기를 단일재료인 폴리프로필렌 정도까지 개선하였다.

• 펄프종이기술
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• 제34권5호
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• pp.49-55
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• 2002

A new method is proposed for the on-line measurement of the fiber orientation of sheet materials. The measurement of fiber orientation is very important in manufacturing paper sheets, non-woven fabrics, and glass sheets, because fiber orientation strongly affects product properties represented by, for example, dimensional stability of paper. A method developed in this research utilizes anisotropy of dielectric constants of sheet materials as a key characteristic to determine the fiber orientation. The new on-line sensor, consisting of 5 microwave dielectric resonators set in different directions, was designed to detect the fiber orientation while paper is running with high speed on a paper machine. This sensor can determine the direction and the degree of fiber orientation from the measured direction of the maximal dielectric constant and its variation, respectively. The fundamental performance of this system was examined by the static measurement of printing grade paper, which gave a satisfactory result. Then, the dynamic measurements were done at a speed of 1,000 m/min by using a high-speed test-coating machine.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.157-163
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• 2000

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and joining problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. In this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this ; joining efficiency of GMT-Sheet, increases as lap joint length L increases. Increase of compression ration cause decrease of joining efficiency after of GMT-Sheet, joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We have better design the structure so as not occur to stress centralization on the joining part.

• 대한기계학회논문집
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• 제18권9호
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• pp.2396-2403
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• 1994

An experimental study on material characterization and mechanical properties of SMC(Sheet Molding Compounds) compression method parts was carried out. Simple compression test using grease oil as a lubricant was carried out to characterize flow stress of SMC at elevated temperatures. Two different mold temperatures, $130^{\circ}C{\;}and{\;}150^{\circ}C$ and two different mold speeds, 15, 45 mm/min were used for preparing the specimen of SMC compression molded parts. Surface roughness, tensile, and 3-point bending tests were used to determine the effects of molding temperatures and speeds on mechanical properties of compression molded SMC parts. Orientation and distribution of glass fiber in the compression molded SMC parts were also investigated by photographing the burnt flat specimen and taking SEM(Scanning Electron Microscope) of cross-sectional T-specimen.

• 콘크리트학회논문집
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• 제19권4호
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• pp.421-431
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• 2007

본 연구의 주 목적은 유리 및 탄소단섬유 (chopped fiber)와 에폭시 및 비닐에스터수지 (resin)를 외기에서 혼합하여 요철이 많은 콘크리트 표면에 고속의 압찰 공기로 랜덤하게 분사하여 기존 콘크리트 구조물을 보강하는 새로운 공법, 즉 sprayed FRP 보수보강 공법을 개발하는 것으로서, 본 연구에서는 sprayed FRP 보강을 위한 치적의 재료 물성치를 제시하고자 유리 및 탄소단섬유의 길이, 단섬유와 에폭시 및 비닐에스터수지의 배합 비율 등을 주요변수로 설정하여 재료 인장시험을 실시하였다. 또한 상기 재료 시험 결과를 바탕으로 sprayed FRP 공법을 이용하여 보강된 철근콘크리트 휨 보, 전단 보 및 손상 보의 보강 성능을 실험적 연구를 토대로 평가하였다. 그 결과, 유리 및 탄소단섬유의 길이 38 mm, 섬유와 수지의 배합 비율 1 : 2가 최적 물성치로 제안되었으며, sprayed FRP의 휨 및 전단 보의 보강 효과는 기존 FRP sheet와 유사한 보강 효과를 나타냈으며, 손상 보의 경우 최대 강도의 결과를 비교해보면 보강 보와 동등한 보강 효과가 나타났다. 기존 FRP 설계식의 적용 가능성을 분석해본 결과, sprayed FRP 휨실험체의 경우 기존설계식의 적용이 가능한 것으로 드러났으며, 전단실험체의 경우는 전단강도 저감계수 ${\alpha}=0.18$이 실험값과 근접한 범위 내에서 안전 측으로 설계가 되는 것으로 사료된다.

• 대한기계학회논문집A
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• 제29권6호
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• pp.876-888
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• 2005

Tensile properties and fracture toughness of monolithic aluminum, fiber reinforced plastics and glass fiber/aluminum hybrid laminates under tensile loads have been investigated using plain coupon and single-edge-notched specimens. Elastic modulus and ultimate tensile strength of GFMLs showed different characteristic behaviors according to the Al kind, fiber orientation and composition ratio. Fracture, toughness of A-GFML-UD which was determined by the evaluation of $K_{IC}$ and $G_{IC}$ based on critical load was similar to that of GFRP-UD and was much higher than monolithic Al. Therefore, A-GFML-UD presented superior fracture toughness as well as prominent damage tolerance in comparison to its constituent Al. By separating Al sheet from GFMLs after the test, optical microscope observation of fracture zone of GFRP layer in the vicinity of crack tip revealed that crack advance of GFMLs depended on the orientation of fiber layer as well as Al/fiber composition ratio.

• 한국염색가공학회지
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• 제27권3호
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• pp.165-174
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• 2015

To develop automobile parts, the unsaturated polyester based matrix resin(PR)/reinforcement(randomly oriented chopped E-glass fiber, GF) composites were prepared using sheet molding compound(SMC) compression molding. The effects of GF length(0.5, 1.0 1.5 and 2.0inch)/content (15, 20, 25, 30wt%) and number of ply(3, 4 and 5) on the specific gravity and mechanical properties of PR/GF composites were investigated in this study. The optimum length of GF was found to be about 1.0inch for achieving improved mechanical properties(tensile strength and initial modulus). The tensile strength and initial modulus of composites increased with increasing GF content up to 30wt%, which is favorable content range for SMC. The specific gravity, tensile strength/initial modulus, compressive strength/modulus, flexural strength/modulus and shear strength increased with increasing the number of ply up to 5, which is the maximum number of ply range for SMC. The effectiveness of ply number increased in the flexural strength > shear strength > compressive strength > tensile strength.

• 한국생산제조학회지
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• 제9권6호
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• pp.41-48
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• 2000

The Compression molding process is widely used in the automotive industry to produce parts that are large, thin, light-weight, strong and stiff. Compression molded parts are formed by squeezing a glass fiber reinforced polypropylene sheet, known a glass mat thermoplastic(GMT), between two heated cavity surfaces. In this study, the anisotropic viscosity of the Unidirectional Fiber-Reinforced Plastic Composites is measured using the parallel plastometer and the composites is treated as an incompressible Newtonian fluid. The effects of molding parameter and fiber contents ratio on longitudinal/transverse viscosity are also discussed.