• 한국구조물진단유지관리공학회 논문집
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• 제22권3호
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• pp.53-59
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• 2018

본 논문에서는 재활용 필름을 사용한 친환경 그리드형 보강재와 사전에 충진재의 혼입을 통해 분산성을 향상시킨 섬유를 도로 포장층에 복합적으로 적용한 공법의 현장 적용성을 분석하였다. 그리드형 보강재를 구성하고 있는 필름은 폐기된 PE수지를 재활용하여 친환경성을 강조하였고, 아스콘 혼입 섬유는 아스콘 충진재의 사전 혼입을 통한 섬유의 분산성을 확보한 것이다. 복합 섬유를 혼입한 교량 포장층을 시공함에 있어 발생할 수 있는 제반 상황을 사전에 인지할 수 있도록, Mock Up 포장층에 대한 기본적인 성능 분석을 실시하였다. 분석 결과, 친환경 그리드 보강재와 분산성 섬유를 함유한 포장층에서 강도 및 응력, 처짐 저항성에서 모두 기능성이 향상된 것을 확인할 수 있었다. 그러므로, 섬유 실제 현장 적용시 친환경성 재료 도입과 더불어 안전성 측면에도 효율적인 공법이라고 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.691-696
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• 1999

This paper is aimed to investigate flexural rehabilitation effect o pre-loaded reinforced concrete beams strengthened by carbon fiber sheet. Main Test parameters are reinforcement ratio and the magnitude of pro-loading and seven test beams are analyzed rehabilitation effect by carbon fiber sheet, load-deflection, failure mode, stress of reinforcing bar by the magnitude of pre-loading. Test results show that internal force was showed pre-loaded specimens lower than no-loaded specimens during rehabilitation and changing stiffness was showed in the same was and failure mode showed brittle failure from all specimens.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권12호
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• pp.978-982
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• 2009

본 논문에서는 다수의 강화 학습 에이전트들의 학습 결과 및 Expert의 지식을 하나의 학습 알고리즘으로 융합하는 강화학습인 "potential-based" reinforcement learning(RL)기법에 불확실한 환경에서의 의사결정 알고리즘인 Case-based Decision Theory(CBDT)를 적용한 "RLs-CBDT"를 제안한다. 그리고 테트리스 실험을 통하여 기존의 RL 알고리즘에 비해 RLs-CBDT가 최적의 정책에 더 마르게 수렴하는 것을 보인다.

• 한국전산구조공학회논문집
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• 제29권5호
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• pp.397-403
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• 2016

1970년대 이후 한국의 빠른 경제성장 동안에 수로나 철도 등 많은 지중구조물들이 건설되었다. 1988년에 내진설계가 의무화되었으나, 1988년 이전의 지중 구조물들은 내진설계가 반영되지 않았다. 따라서, 이러한 지중 구조물들은 지진이 일어났을 때 안전성을 확보하기 위해 효과적인 내진 보강방법이 필요하다. 그러한 이유로, 본 연구에서는 새롭게 개발된 보강재를 이용한 RC 박스 지중 구조물 우각부 보강공법의 내진성능에 대하여 분석하였다. 이 공법은 박스구조물 우각부에 Pre-flexed member를 설치하여 외력에 저항력을 증대시키는 원리이다. 타당성을 검증하기 위해서 새로이 개발된 보강재와 기존의 보강재를 실험과 유한요소해석으로 비교하였다. 유한요소모델에서 강재의 비선형 모델은 J2 Plasticity Model을 기초로 하고 콘크리트는 CEB-FIP MODEL CODE 1990로 모델링되었다. 또한, 설계반영을 위한 박스 구조물과 보강재와의 합성률을 산정하였다. 보강재와 박스구조물은 Tie에 의해 완전 부착된 상태의 연결조건 하에서 해석이 수행되었으며, 하중-변위곡선에서 실험과 유한요소해석의 결과가 서로 일치하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.687-691
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• 2001

Al alloy matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by hot pressing to investigate mechanical properties. The stress-strain behavior of the composites was evaluated at temperatures between 363K and room temperature as a function of pre-strain by using experimental and finite element analysis, and both cases showed that the tensile stress at 363K was higher than that of the room temperature. Especially, the tensile stress of this composite increases with increasing the amount of pre-strain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being pre-strained.

• KCI Concrete Journal
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• 제12권1호
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• pp.69-77
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• 2000

The reinforced concrete(RC) flexural members strengthened with steel plate/CFS at soffit have initial stresses and strains in reinforcements and concrete caused by the service loads at the time of retrofitting works. These initial residual stresses and strains of strengthened beams may affect the flexural performance of the rehabilitated beams. The objective of this study is to evaluate and verify the effectiveness of rehabilitation by external bonded steel plates and CFS to the tension face of the beams under three conditions of pre-loading. Thirteen beam specimens are tested and analyzed. Main test parameters are pre-loading conditions, strengthening materials and reinforcement ratio of specimens. The effect of test parameters on the strengthened beams is analyzed from the maximum load capacity, load-deflection relationship, state of stress of the materials. crack propagation phase, and failure modes. Both test results and design formulas of ACI Code provisions are compared and evaluated.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제11권4호
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• pp.105-112
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• 2022

최근 환경의 변화에 적응적이고 특정 목적에 부합하는 오토스케일링 정책을 만들기 위해 강화학습 기반 오토스케일링을 사용하는 연구가 많이 이루어지고 있다. 하지만 실제 환경에서 강화학습 기반 수평적 파드 오토스케일러(HPA, Horizontal Pod Autoscaler)의 정책을 학습하기 위해서는 많은 비용과 시간이 요구되며, 서비스를 배포할 때마다 실제 환경에서 강화학습 기반 HPA 정책을 처음부터 다시 학습하는 것은 실용적이지 않다. 본 논문에서는 쿠버네티스에서 강화학습 기반 HPA를 구현하고, 강화학습 기반 HPA 정책에 대한 학습을 가속화하기 위해 대기행렬 모델 기반 시뮬레이션을 활용한 전이 학습 기법을 제안한다. 시뮬레이션을 활용한 사전 학습을 수행함으로써 실제 환경에서 시간과 자원을 소모하며 학습을 수행하지 않아도 시뮬레이션 경험을 통해 정책 학습이 이루어질 수 있도록 하였고, 전이 학습 기법을 사용함으로써 전이 학습 기법을 사용하지 않았을 때보다 약 42.6%의 비용을 절감할 수 있었다.

• Geomechanics and Engineering
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• 제11권2호
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• pp.177-195
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• 2016

To secure the stability of geotechnical infrastructures and minimize failures during the construction process, a number of support systems have been introduced in the last several decades. In particular, stabilization methods using steel bars have been widely used in the field of geotechnical engineering. Rock bolt system is representative support system using steel bars. Pre-stressing has been applied to enhance reinforcement performance but can be released because of the failure of head or anchor sections. To overcome this deficiency, this paper proposes an innovative support system that can actively reinforce the weak ground along the whole structural element by introducing an active tension bolt containing a spring unit to the middle of the steel bar to increase its reinforcement capacity. In addition, the paper presents the support mechanism of the active tension bolt based on a theoretical study and employs an experimental study to validate the performance of the proposed active tension bolt based on a down-scaled model. To examine the feasibility of the active tension unit in a pillar, the paper considers a pullout test and a small-scale experimental model. The experimental results suggest the active tension bolt to be an effective support system for pillar reinforcement.

• Structural Engineering and Mechanics
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• 제49권3호
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• pp.373-393
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• 2014

A finite element model for predicting the entire nonlinear behavior of reinforced high-strength concrete continuous beams is described. The model is based on the moment-curvature relations pre-generated through section analysis, and is formulated utilizing the Timoshenko beam theory. The validity of the model is verified with experimental results of a series of continuous high-strength concrete beam specimens. Some important aspects of behavior of the beams having different tensile reinforcement ratios are evaluated. In addition, a parametric study is carried out on continuous high-strength concrete beams with practical dimensions to examine the effect of tensile reinforcement on the degree of moment redistribution. The analysis shows that the tensile reinforcement in continuous high-strength concrete beams affects significantly the member behavior, namely, the flexural cracking stiffness, flexural ductility, neutral axis depth and redistribution of moments. It is also found that the relation between the tensile reinforcement ratios at critical negative and positive moment regions has great influence on the moment redistribution, while the importance of this factor is neglected in various codes.

• Structural Engineering and Mechanics
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• 제27권6호
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• pp.741-771
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• 2007

Tests were conducted on two partially pre-stressed concrete solid beams subjected to combined loading of bending, shear and torsion. The beams were designed using the Direct Design Method which is based on the Lower Bound Theorem of the Theory of Plasticity. Both beams were of $300{\times}300mm$ cross-section and 3.8 m length. The two main variables studied were the ratio of the maximum shear stress due to the twisting moment, to the shear stress arising from the shear force, which was varied between 0.69 and 3.04, and the ratio of the maximum twisting moment to the maximum bending moment which was varied between 0.26 and 1.19. The required reinforcement from the Direct Design Method was compared with requirements from the ACI and the BSI codes. It was found that, in the case of bending dominance, the required longitudinal reinforcements from all methods were close to each other while the BSI required much larger transverse reinforcement. In the case of torsion dominance, the BSI method required much larger longitudinal and transverse reinforcement than the both the ACI and the DDM methods. The difference in the transverse reinforcement is more pronounce. Experimental investigation showed good agreement between design and experimental failure loads of the beams designed using the Direct Design Method. Both beams failed within an acceptable range of the design loads and underwent ductile behaviour up to failure. The results indicate that the Direct Design Method can be successfully used to design partially prestressed concrete solid beams which cater for the combined effect of bending, shear and torsion loads.