• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.447-456
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• 2008

This paper suggests a modified debonding failure model for the externally bonded prestressed CFRP plate strengthening system. In order to reduce the error that may occur in the experimental results, statistical analysis of the experimental results produced by previous researchers was conducted to propose a debonding failure model. The experimental results of beams strengthened with bonded CFRP plates have made it possible to verify the debonding failure occurring before the final failure in the prestressing system. The corresponding strain increased with the effective prestress. Accordingly, the debonding failure model was modified by considering the effective prestress so as to fit with the CFRP prestressing system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.47-57
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• 2023

In this study, pull-out tests were performed to investigate the effects of stirrup spacing, rebar diameter, and corrosion rate on bond strength of deformed bars in reinforced concrete. Twelve pull-out specimens with different stirrup spacing, rebar diameter, and corrosion rate were prepared following the RILEM RC6 guidelines. The test results showed that the bond strength of specimens with stirrups increased when the corrosion rate was less than 3%, whereas it decreased when the corrosion rate was more than 3%. On the other hand, the bond strength of specimens without stirrups decreased as the corrosion rate increased. The effect of rebar diameter was less significant compared to those of stirrup spacing and corrosion rate. A bond strength model for pull-out specimens was proposed considering stirrup ratio and corrosion rate, and the model showed the lowest error among the previous models.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.271-278
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• 2019

The corrosion of reinforcements embedded in concrete causes severe deterioration in reinforced concrete structures. As a countermeasure, epoxy coated reinforcements are used to prevent corrosion of reinforcements. When epoxy coated bars are used, the resistance of corrosion is excellent, but epoxy coating on the bars have a disadvantage of reduction in bond capacity comparing to that of normal bars. Therefore, it is necessary to confirm the bond performance of epoxy coated reinforcements through experimental and analytical methods. Bond behaviors of epoxy coated bars for various diameters of 13 and 19mm and thicknesses of cover concrete of 3 types(ratio of cover to bar diameter) are examined. As the diameters of the epoxy coated bars increase, the difference of bond strength between epoxy coated and uncoated bars also increases and damage patterns showed pull out failure. In addition, finite element analysis was performed based on the bond-slip relationship obtained by direct pullout test and compared with the flexural test results. It is considered that flexural member test is more useful than pullout test for simulating the behavior of actual structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.43-53
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• 2011

For reinforced concrete members, the bond strength is one of the important factors between two materials: concrete and reinforcing element. This study concerns the bond strength of deformed bars in artificial lightweight aggregate concrete by pull-out test. 144 cubic specimens were manufactured for the test. concrete compressive strength, size of deformed bar and embedment lengths were considered as variables in this study. Normal concrete with W/C ratio 50% specimens were tested for the comparison. Test results included the bond stress-slip responses and modes of failure. Bond strength increased with an increase of compressive strength of concrete according to W/C ratio. The equation of bond stress of polymer-modified lightweight aggregate concrete were proposed by regression analysis based on the result.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.769-777
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• 2003

The strengthening of concrete structures in situ with externally bonded carbon fiber is increasingly being used for repair and rehabilitation of existing structures. Because carbon fiber is attractive for this application due to its good tensile strength, resistances to corrosion, and low weight. Generally bond strength and behavior between concrete and carbon fiber mesh(CFM) is very important, because of enhancing bond of CFM. Therefore if bond strength is sufficient, it will be expect to enhance reinforcement effect. Unless sufficient, expect not to enhance reinforcement effect, because of occuring bond failure between concrete and CFM. In this study, the bond strength and load-displacement response of CFM to the concrete by the direct pull-out test(the tensile-shear test method) were investigated using the experiment and the finite element method analysis with ABAQUS. The key variables of the experiment are the location of clip, number of clips and thickness of cover mortar. The general results indicate that the clip anchorage technique for increasing bond strength with CFM appear to be effective to maintain the good post-failure behavior.

• Journal of the KSME
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• v.34 no.4
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• pp.239-252
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• 1994

광섬유 모재제조공정인 OVD와 VAD방식에서의 입자부착 증진을 위해서 외부에서 전기장을 가 해서 실리카입자를 대전시킨 뒤에 타겟으로 부착을 시키는 전기영동원리를 이용하는 방법을 소 개하였다. 실험에서는 디스크형 타겟을 사용하여 타겟 근방에서의 온도, 전기장분포를 측정하였고 입자부착실험을 수행했다. 그 결과 9cm 타겟에 -1.6kv가 가해\ulcorner을 때 전기영동으로 인한 부착률 증가는 열영동으로 인한 효과의 약 35%가 되었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.759-764
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• 1998

원전 중대사고시 에어로졸 거동 현상과 분석 모델에 대한 이해의 증대와 분석 능력을 재선하기 위한 목적으로 OECD ISP-40에 참여하여 SR-11 에어로졸 부착 및 재부유 실험을 분석하였다.MELCOR 코드에 의한 부착 분석 결과, 부착량을 과소 예측하는 것으로 나타나 열영동 상관식 계수의 조정과 난류 효과의 고려 등 모델의 개선이 필요한 것으로 보이며, 분석모델 작성시 입자크기의 분포에 주의해야 함을 알 수 있었다. VICTORIA 코드는 부착량을 약간 과도하게 예측하였고 재부유가 초기에 과도하게 일어나는 것으로 예측하는 모델의 제한점을 나타냈다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.109-116
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• 2008

In order to test the adhesive capacity of carbon fiber sheet, a static loading method for bending-behavior-type beam specimens, cut in half was developed and test was conducted with compressive strength of concrete set as the test parameter. The tests were performed to prescribe adhesive shear strength based upon the result of shear failure as well as verification of testing method. First of all, the test method proved to be reliable in determining the adhesive shear strength. The test result also exhibited two types of variations in adhesive shear strength. Among two types of variations, average and minimum values for adhesive shear strength, relatively stable results, 3.41MPa and 2.11MPa, respectively. Particularity in the adhesive shear strength with respect to compressive shear strength was not found.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.143-151
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• 2006

This paper presents the comparison of the goodness-of-fit test of analytical bond models between concrete and steel or GFRP reinforcements. Bond test specimens were prepared in accordance with the CSA codes and the rebars used in the test were steel and two types of commercial GFRP rebar products. Using the test data, a bond model was proposed, and comparison of goodness-of-fit test for existing bond models and proposed bond model was carried out by the least squares method. The result indicates that the proposed bond model has better goodness-of-fit test than the existing ones.

• Annual Conference on Human and Language Technology
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• 2017.10a
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• pp.298-300
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• 2017

본 논문에서는 단순하지만 효과적인 단어 표현 방법인 Bags of Features에 대한 비교 실험을 수행한다. Bags of Features는 어휘집의 크기에 제한이 없으며, 문자 단위의 정보를 반영하고, 벡터화 과정에서 신경망 구조에 의존하지 않는 단어 표현 방법이다. 영어 품사 부착 실험을 사용하여 실험한 결과, one-hot 인코딩을 사용한 모델과 대비하여 학습 데이터에 존재하지 않는 단어의 경우 49.68%, 전체 부착 정확도는 0.96% 향상이 관찰되었다. 또한, Bags of Features를 사용한 모델은 기존의 영어 품사 부착 분야의 최첨단 모델들 중 학습 데이터 외의 추가적인 데이터를 활용하지 않는 모델들과 비견할 만한 성능을 보였다.