• Structural Engineering and Mechanics
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• 제26권4호
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• pp.427-439
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• 2007

The exploitation of fibre reinforced polymer composites, as external reinforcement is an evergreen and well-known technique for improving the structural performance of reinforced concrete structures. The demand to use FRP composites in the civil engineering industry is mainly due to its high strength, light weight, and stiffness. This paper exemplifies the shear strength of partially precracked reinforced concrete rectangular beams repaired with externally bonded Bi-Directional Carbon Fibre Reinforced Polymer (CFRP) Fabrics strips. All specimens were cast in the laboratory environment without any internal shear reinforcement. The test parameters were longitudinal tensile reinforcement, shear span to effective depth ratio, spacing of CFRP strips, and orientation of CFRP reinforcement. It mainly focuses on the shear capacity and modes of failure of the CFRP strengthened shear beams. Results have shown that the CFRP repaired beams attained a shear enhancement of 32% and 107.64% greater than the control beams. This study underscores that the CFRP strip technique significantly enhanced the shear capacity of precracked reinforced concrete rectangular beams without any internal shear reinforcement.

• Steel and Composite Structures
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• 제33권5호
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• pp.729-746
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• 2019

The nonlinear behavior of single- and multi-story steel plate shear walls (SPSWs) strengthened with three different patterns of fiber reinforced polymer (FRP) laminates (including single-strip, multi-strip and fully FRP-strengthened models) is studied using the finite element analysis. In the research, the effects of orientation, width, thickness and type (glass or carbon) of FRP sheets as well as the system aspect ratio and height are investigated. Results show that, despite an increase in the system strength using FRP sheets, ductility of reinforced SPSWs is decreased due to the delay in the initiation of yielding in the infill wall, while their initial stiffness does not change significantly. The content/type/reinforcement pattern of FRPs does affect the nonlinear behavior characteristics and also the mode and pattern of failure. In the case of multi-strip and fully FRP-strengthened models, the use of FPR sheets almost along the direction of the infill wall tension fields can maximize the effectiveness of reinforcement. In the case of single-strip pattern, the effectiveness of reinforcement is decreased for larger aspect ratios. Moreover, a relatively simplified and approximate theoretical procedure for estimating the strength of SPSWs reinforced with different patterns of FRP laminates is presented and compared with the analytical results.

• Computers and Concrete
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• 제12권4호
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• pp.443-498
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• 2013

A detailed finite element modeling is presented for the simulation of the nonlinear behavior of reinforced concrete structures which manages to predict the nonlinear behavior of four different experimental setups with computational efficiency, robustness and accuracy. The proposed modeling method uses 8-node hexahedral isoparametric elements for the discretization of concrete. Steel rebars may have any orientation inside the solid concrete elements allowing the simulation of longitudinal as well as transverse reinforcement. Concrete cracking is treated with the smeared crack approach, while steel reinforcement is modeled with the natural beam-column flexibility-based element that takes into consideration shear and bending stiffness. The performance of the proposed modeling is demonstrated by comparing the numerical predictions with existing experimental and numerical results in the literature as well as with those of a commercial code. The results show that the proposed refined simulation predicts accurately the nonlinear inelastic behavior of reinforced concrete structures achieving numerical robustness and computational efficiency.

• 한국지반공학회지:지반
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• 제10권4호
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• pp.133-152
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• 1994

In the present study, an economic design of Anchored Geosynthetic(AG) System applied mainly to reinforce unstable soil slopes is investigated. For this purpose methods of stability analysis are developed to determine the optimum installation angle, required minimum length and maximum spacing of nails. Anchorage of nails within the soil mass is achieved by frictional resistance to pull out along the effective length of the nails. Cases of infinite slope and finite slope are dealt with individually. Silce methods of stability analysis developed in the present study are limit-equilibrium-based. For the case of finite slope Spencer method which considers interslice force is modified to evalyate the overall stability. In addition, the effects of various design parameters on requried length and spacing of nails corresponding to the optimum orientation of nails are analyzed. Based on the analysis, a simplified equation is given for the optimum nail orientation. Also the importance of optimum nail orientation is illustrated throughout design example, and the appropriateness of judgment criterion are examined.

• 한국해양공학회지
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• 제11권3호
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• pp.69-75
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• 1997

A A12024-T3 plate has been reinforced with AFRP to be a Hybrid-Composite, APAL. The fatigue life of the APAL has been investigated. The effects of bonding surface, numbers of AFRP bonded and AFRP orientation on fatigue life have been compared with A12024-T3 plate. Fatigue life of APAL has been remarkedly increased compared with that of A12024-T3 plate. The fatigue life has depended on bonding surface and AFRP orientation, but no relationship could be found with numbers of AFRP laminates.

• 한국환경교육학회지:환경교육
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• 제9권1호
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• pp.17-29
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• 1996

'Control of Locus of Reinforcement(LOCR)' is considered one of the main important factors on responsible environmental behaviors(REB). It is defined as 'an individual's perception of his or her ability to bring about change through his or her behavior'. This phychological construct is divided in two, external locus and internal locus. Internal locus of reinforcement is important as predictor for REB. Lately, 'The Environmental Action Internal Control Index:EAICI' was developed. It is a valid and reliable instrument to measure relationships of two variables. The purposes of this study were to analyse the orientation of LOCR in high school students and relations with LOCR to REB. By the results, EAICI scores of total students, males, females are 99.83, 95.10, 104.56, respectively. LOCR of females was stronger and more internal than one of males. The item scores for behaviors that reduce the amount of household trash by reusing and recycling and convince someone to do this are 4.31, 4.05, respectively. The item scores for behaviors that convince someone to sign a petition regarding on environmental issues, convince someone to reuse envelopes by putting a label over the old address and convince someone to keep car tires properly inflated are 3.09, 3.09, 3.04, respectively. It shows that EAICI scores are dependent upon the degree of the chances and experiences to meet the various environmental events.

• 한국콘텐츠학회논문지
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• 제18권6호
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• pp.574-599
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• 2018

본 연구는 기업에 근무하는 구성원을 대상으로 리더의 공유리더십과 조직구성원의 혁신행동에 대한 인식에서 학습지향성과 폐기학습이 미치는 영향을 분석함으로써 리더의 공유리더십의 중요성에 대한 시사점을 제시하는데 그 목적이 있다. 본 연구의 설문조사는 국내 중소기업에서 지식근로자로 근무하고 있는 조직구성원을 대상으로 실시하였고, 회수된 설문지중 총 387개를 SPSS 24.0 통계패키지를 사용하여 통계분석 방법을 실시하였다. 연구결과, 리더의 공유리더십과 혁신행동, 공유리더십과 학습지향성 그리고 학습지향성과 혁신행동에 정(+)의 영향을 미쳤다. 또한 학습지향성은 공유리더십과 혁신행동의 관계에서 매개역할을 하였으며, 폐기학습은 공유리더십과 학습지향성의 관계를 강화하였다. 본 연구결과가 함의하는 바는 조직구성원의 혁신행동을 향상시키기 위해서는 조직구성원 스스로가 적극적인 폐기학습과 학습지향성 향상을 위한 지속적인 강화 활동이 필요하다. 또한, 조직구성원과 조직에 대한 리더의 공유리더십이 더욱 중요하다는 결과를 보이고 있다.

• 대한기계학회논문집
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• 제17권5호
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• pp.1106-1114
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• 1993

본 연구에서는우수한 섬유강화 고분자복합판의 제조 및 개량을 섬유구조의 분리. 배향의 관점에서 연구한다. 유리섬유매트는 유리섬유를 50mm의 길이로 균일하 게 절단하여 공기중에서 분산시켜 6~7mm두께로 만들고,이 유리섬유매트를 바늘의 종류와 스트레칭 횟수에 따라 니들펀칭하여 유리섬유의 매트구조를 변화시킨다. 유리 섬유의 매트구조 별로 모재와 적층시킨 다음 열압축프레스를 사용하여 1차로 시이트를 제작하고, 이 제작된 시이트를 가열로로 가열하여 2차 고온압축 프레스성형한다. 이 때 섬유와 모재의 분리 및 배향의 상관관계를 나타내는 상관계수를 구하고, 이 계수에 미치는 매트 구조의 영향에 대한 실험결과를 보고한다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.184-191
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• 2003

In this paper, a mathematical framework based on a homogenisation technique to simulate 'umbrella arch reinforcement system' (UARS) and its implementation into a 3D Finite Element program that can consider stage construction situations are presented. The constitutive model developed allows considering the main design parameters of the problem and only requires geometrical and mechanical properties of the constituents. Additionally, the use of a homogenisation approach implies that the generation of the Finite Element mesh can be easily produced and that re-meshing is not required as basic geometrical parameters such as the orientation of the pipes are changed. The model developed is used to simulate tunnelling with the UARS. From the analyses, the effects of the main design parameters on the elastic and the elastoplastic analyses are considered.

• 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.