• Computers and Concrete
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• 제11권4호
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• pp.351-364
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• 2013

This paper presents results from an analytical investigation of the behavior of steel reinforced concrete circular column sections with additional Glass Fiber Reinforced Polymers (GFRP) bars. The primary application of this composite section is to relocate the plastic hinge region from the column-footing joint where repair is difficult and expensive. Mainly, the study focuses on the development of the full nominal moment-axial load (M-P) interaction diagrams for hybrid concrete sections, reinforced with steel bars as primary reinforcement, and GFRP as auxiliary control bars. A large parametric study of circular steel reinforced concrete members were undertaken using a purpose-built MATLAB(c) code. The parameters considered were amount, location, dimensions and mechanical properties of steel, GFRP and concrete. The results indicate that the plastic hinge was indeed shifted to a less critical and congested region, thus facilitating cost-effective repair. Moreover, the reinforced concrete steel-GFRP section exhibited high strength and good ductility.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.928-933
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• 2004

The vibration characteristic is a primary design factor. The cylindrical shells are used as a primary components of complex structure. also, The cylindrical shells have oblique angle. In this study, The vibrational characteristics of steel and plain wave GFRP cylindrical shell with an oblique end are given by experimental and finite element method. To be find characteristic of the oblique end, the mass of the cylindrical shell is maintained. Natural frequency and mode shapes of isotropic and plain weave composite shells are obtained by modal test. The results are compared with those of the finite element method. The simply supported boundary conditions with bolts along the circumferential direction of the GFRP shell are well achieved. Also, The clamped boundary conditions is applied to the steel specimen. Those are shown to agree well with the analytical results and finite element analysis results.

• Composites Research
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• 제15권2호
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• pp.48-54
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• 2002

This paper presents some research topics for advanced composites which have been conducted in Ben laboratory, College of industrial Technology, Nihon University. The topics are applications of shape memory alloy(SMA) to composite structures, dynamic responses of CFRP and GFRP structures, fabrication of new type of GFRP, fatigue and weatherability strength of CFRP and new concept of joint for FRP structures, respectively.

• International Journal of Safety
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• 제3권1호
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• pp.1-5
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• 2004

This study discusses frequency analysis based on autoregressive (AR) time series model, and the characterization of surface quality in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The experimental correlations between the fiber pull-out and AR model coefficients are then established.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3562-3569
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• 2013

콘크리트 구조물은 외부환경에 의하여 시간이 지남에 따라 그 성능이 지속적으로 감소되며 이를 보강하기 위하여 새로운 재료의 개발 및 적용에 대한 연구가 활발히 진행되고 있다. FRP복합재료의 경우, 높은 강도-중량비, 우수한 내식성과 시공성을 갖추고 있어 노후된 구조물의 보수 및 보강재료로 많은 관심을 받고 있으나 현장적용 시FRP 복합재료의 외부환경에 대한 신뢰성 및 설계기준 부족으로 재료의 장점에도 불구하고 그 활용도는 그리 증가하지 못하였다. 본 연구에서는 콘크리트 압축부재의 횡 구속용으로 적용 가능한 GFRP 보강재에 대하여 고온으로의 온도변화에 따른 재료적 특성과 구속효과에 대한 구조적 거동을 조사하였다. 이를 위하여 GFRP 보강재의 온도에 따른 인장 물성치와 콘크리트 부재의 구속 압축효과를 실험변수로 각각 선정하였으며 GFRP로 횡 구속된 콘크리트 시편을 설정온도별로 각각 3개씩 제작하여 실험연구를 수행하였다. 실험 시 온도변화의 경우 고온로를 사용하여 일정 시간동안 실험온도에 노출되도록 시편을 거치하였으며 압축성능평가의 경우 만능재료시험기(UTM)를 통하여 섬유의 횡 구속에 따른 보강효과 변화를 파악하였다. 최종적으로 온도변화에 따른 GFRP재료의 인장특성은 점진적으로 감소하는 것을 정량적으로 알 수 있었으며, 콘크리트 횡 구속 시 GFRP 보강재에 의한 구속능력은 $150^{\circ}C$까지 온도가 상승함에 따라 감소하는 것을 본 연구를 통하여 관찰하였다.

• 비파괴검사학회지
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• 제37권2호
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• pp.99-105
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• 2017

Many composite materials are used in the aerospace industry because of their excellent mechanical properties. However, the nature of aviation exposes these materials to high temperature and high moisture conditions depending on climate, location, and altitude. Therefore, the molecular arrangement chemical properties, and mechanical properties of composite materials can be changed under these conditions. As a result, surface disruptions and cracks can be created. Consequently, moisture-impregnating defects can be induced due to the crack and delamination of composite materials as they are repeatedly exposed to moisture absorption moisture release, fatigue environment, temperature changes, and fluid pressure changes. This study evaluates the possibility of detecting the moisture-impregnating defects of CFRP and GFRP honeycomb structure sandwich composite materials, which are the composite materials in the aircraft structure, by using an active infrared thermography technology among non-destructive testing methods. In all experiments, it was possible to distinguish the area and a number of CFRP composite materials more clearly than those of GFRP composite material. The highest detection rate was observed in the heating duration of 50 mHz and the low detection rate was at the heating duration of over 500 mHz. The reflection method showed a higher detection rate than the transmission method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 추계학술대회 논문집
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• pp.43-45
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• 1988

This paper deals with the effect amino silane coupling agent for the composite insulating material (GFRP). Three kinds of coupling agent treatments are studied, that is treatment on glass fiber, epoxy resin and both glass fiber and epoxy resin. The result shows that the optimum electrical and mechanical properties is obtained for the sample treated on the glass fiber with 0.3% amino silane water solution.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.48-52
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• 2002

This paper describes the need for a ductile Fiber Reinforced Plastic(FRP) reinforcement for Concrete Structures. Using the material hybrid and geometric hybrid, it is demonstrated that the pseudo-ductility Characteristic can be generated in FRP rebar. Ductile hybrid FRP bars were successfully fabricated at Ø3mm and Ø10mm nominal diameters using the braidtrusion process. Tensile and bending specimens from these bars were tested and compared with behavior of stress-strain of steel bar and GFRP rebar

• Steel and Composite Structures
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• 제15권3호
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• pp.267-279
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• 2013

This article describes a simple and cost effective fabrication procedure by using hand lay-up technique that is employed for the manufacturing of thin-walled axi-symmetric composite shell structures with carbon, glass and hybrid woven fabric composite materials. The hand lay-up technique is very commonly used in aerospace and marine industries for making the complicated shell structures. A generic fabrication procedure is presented in this paper aimed at manufacture of plain Carbon Fabric Reinforced Plastic (CFRP) and Glass Fabric Reinforced Plastic (GFRP) shells using hand lay-up process. This paper delivers a technical breakthrough in fabrication of composite shell structures without any joints and wrinkling. The manufacture of stiffened CFRP shells, laminated CFRP shells and hybrid (carbon/glass/epoxy) composite shells which are valued by the aerospace industry for their high strength-to-weight ratio under axial loading have also been addressed in this paper. A fabrication process document which describes the major processing steps of the composite shell manufacturing process has been presented in this paper. A study of microstructure of the glass fabric/epoxy composite, carbon fabric/epoxy composite and hybrid carbon/glass/fabric epoxy composites using Scanning Electron Microscope (SEM) has been also carried out in this paper.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.123-124
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• 2011