• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.277-289
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• 2011

This study proposes a new testing method for shear bearing capacity of FRP-concrete interface, which could well consider a loading condition corresponding to a tunnel lining undergoing axial compression and could be easily carried out with a simply specified specimen. A parametric study is carried out for capturing an optimized condition of coarse-sand coating of FRP, which governs shear bearing capacity of FRP-concrete interface, by using the proposed testing manner in this study. From the parametric study, it is shown that the proposed testing method is reasonably feasible in comparison with the existing testing methods. An optimum condition of coated sand size and sand density is given for the shearing capacity of FRP-concrete interface.

• Magazine of the Korea Concrete Institute
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• v.14 no.2
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• pp.45-50
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• 2002

근년, 철근 콘크리트조 구조부재의 열화 및 건축물의 용도변경에 따라 건축물의 보수 및 보강에 관한 공법의 개발 및 그 효과를 검증하려는 연구가 활발히 진행되고 있다. 이에 따라, 보강공법으로서는 경제성ㆍ시공성 면에서 우수한 탄소섬유시트, 아라미드섬유 시트, 유리섬유시트 보강공법 및 FRP판 보강공법 등 합성수지 접착제를 사용하는 새로운 보강공법들이 폭넓게 연구되어 현장 실용화되어 사용 중에 있다. 그러나, 이들 보강공법에 관한 연구는 주로 구조적인 내력 보강효과 산정에 관한 것이 대부분이고 보강후의 내화성능 및 내구성능에 관한 연구는 매우 부족한 실정이다. 이들 보강공법은 주로 에폭시수지계 접착제에 의하여 콘크리트와 보강재의 접착력에 의하여 내력이 전달되는 메커니즘으로 되어있어 화재가 발생한 경우 내화피복이 없다면 접착제 자체의 연소에 의하여 유독가스의 발생 및 접착강도가 크게 저하되어 그 구조적인 보강성능은 급속히 저하할 것으로 판단된다. 또한, 현재 이들 보강공사는 내화성능의 검토 없이 실제 시공이 이루어지고 있으므로 화재시에는 대형참사를 일으킬 위험성이 있다.(중략)

• Journal of the KSME
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• v.31 no.3
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• pp.251-260
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• 1991

발전 설비를 중심으로 고온 부재의 잔존 수명 진단을 위한 경년 열화도의 측정에 관련된 연구 현황에 대해 극히 좁은 범위 안에서 개략적으로 기술했다. 국내의 산업체에서도 현재 이에 관 련된 문제점을 제시하고 있고 앞으로 이러한 문제의 발생은 그 빈도와 규모면에서 증가하게 될 것이다. 이에 대비하여 기존 방법의 기술적 터득과 데이터의 축적 그리고 측정 정도를 향상시 키기 위한 새로운 측정 방법들의 개발이 시급한 실정이다. 정확한 진단과 수명이 예측을 위해선 본 글에서 설명된 각종 측정법들과, 짧은 식견으로 여기에서는 설명되지 못한 금속학적 고찰을 가미한 수많은 측정법들을 종합적으로 행하여야 할 필요가 있다는 것은 말 할 나위도 없다. 또한 실기 사용 부재의 입수, 나름대로의 정보 교환은 연구 초기 단계에서 부딪치는 수많은 문 제점들을 원활하게 해결하기 위해서는 각 전문분야의 학술적 교류와 더불어 산. 학. 연의 공동 연구가 절실하게 요구된다.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.28-31
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• 2007

자동차 측면충돌시 인체의 상해를 줄이기 위하여 도어 시스템 부품 중에 도어트림이 충격을 차단하고 인체를 보호하는 역할을 하고 있다. 차체 판넬이 변형되어 도어트림에 전달되는 충돌 에너지를 패드가 흡수 하는데 중대한 기능을 한다. 이전에 충격흡수 패드는 외곽부위의 수평면에 의존하여 설계되었으며 이 구조는 점진적으로 충격을 흡수 하는데 문제점이 발견 되었는데 트리즈의 6단계 창의성 기법을 적용하여 패드의 주요 특성을 찾아내고 그 특성에 모순을 해결하여 차종에 적용할 수 있는 기본 단면과 설계 자유도가 높은 충격흡수부재를 개발 하였다.

• Journal of the Korean Institute of Navigation
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• v.22 no.3
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• pp.65-72
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• 1998

The use of high tensile steel plates is increasing in the fabrication of ship and offshore structures. In usual, plate element contributes to inplane stiffness against the action of inplane load. If the plate element has local corrosion, its load carrying capacity under inplane load is expected to be reduced. Until now, however, the research report concerned with this topic has not seen. In this study, a basic study which clarifies the influence of local corrosion on the ultimate collapse strength of plate element subjected to axial compression is carried out by using elasto-platic large deformation finite element analysis. In particular, influence of corrosive area, corrosive thickness and slenderness ratio of dented plate is investigated.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.719-725
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• 2010

The analysis and experimental program of reinforced concrete (RC) structures for resistance against such extreme loads as earthquake, blast, and impact have been carried by many researchers and designers. Under the extreme loads, a large amount of energy is suddenly exerted to the structure, hence if the structure fails to absorb the impact energy, catastrophic collapse may occur. To prevent catastrophic collapse of structures, reinforced concrete must have adeguate toughness or it needs to be strengthened. The FRP strengthening method and SFRC are studied widely in resistance of impact load because of their high energy absorption capacity. In this study, drop weight impact tests were implemented to evaluate the impact resistance of SFRC and FRP strengthened RC beam while the total steel fiber volume fractions was fixed at 0.75% carbon FRP flexural strengthened RC beams. Futhermore, to prevent the shear-plug cracks when the impact load strikes the beams, additional FRP shear strengthening method are applied. The experimental, results showed that the FRP strengthened RC SFRC beams has high resistance of shear-plug cracks and crack width and SFRC has high resistance of concrete spalling failure compared to normal RC beams. The FRP flexural and shear strengthening RC beams has weakness in the spalling failure because the impact load concentrated the concrete face which is not strengthened with FRP sheets.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.289-292
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• 2008

This paper studied experimentally on the structural performance and serviceability of RC beams with high-strength reinforcing bars. Following to the previous research, high-strength reinforcing bars have an negative effect on the deflection and crack depth. But, there are advantages about reducing amount of reinforcement than normal-strength reinforcing bars. So, the purpose of this paper is to analyze the effect of flexural performance on the beams with high-strength reinforcing bars. Three specimens were tested, and the main variable was the yield strength of the reinforcements; SD400, SD600 and SD700. Experimental results shows that the stiffness of members reduced when apply to high-strength reinforcement and equal reinforcement ratio. But the flexural strength of members increased to proportion to the strength and amount of reinforcement. Also, when high-strength reinforcement used, serviceability aspect do not appear to be affected because there is no change for crack number and maximum crack width.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.197-200
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• 2008

An analytical model for predicting the shear strength of prestressed concrete beams was developed, applying the previously proposed strain-based shear strength model. In flexure-compression member without shear reinforcement, compression zone of intact concrete primarily resist to the shear force rather than tension zone. The shear capacity of concrete at the compression zone was defined based on the material failure criteria. The shear capacity of the compression zone was evaluated along the inclined failure surface considering interaction with the normal stress. Since the distribution of normal stress varies due to the flexural deformation of member, the shear capacity was defined as a function of the flexural deformation. Finally, the shear strength was determined at the intersection of the shear capacity curve and the shear demand curve. As a result of the comparisons to prior test data, the proposed model accurately predicted the shear strength of specimens.

• Informatization Policy
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• v.29 no.2
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• pp.66-90
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• 2022

The radical digital transformation and development of the contactless digital economy in the wake of the COVID-19 pandemic are increasing the need to solve various problems such as conflicts of interest among market participants and delays in related laws and regulations. This study investigates the concept and characteristics of the contactless digital economy and identifies the related regulatory issues and resolutions through literature review, news article analysis, and expert interviews. From the literature review, it is identified that the contactless digital economy has eight hyper-innovation characteristics: hyper-intelligence, hyper-connectivity, hyper-convergence, hyper-personalization, hyper-automation, hyper-precision, hyper-diversity, and hyper-trust. From news article analyses and expert interviews, this study identifies various regulatory issues, such as competition between incumbents and new entrants, the collision of constitutional rights, collision of social values, conflict between market participants, absence of laws and regulations, and existence of excessive market power, and then proposes a series of resolutions.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.69-75
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• 2008

Shear tests were carried out on interface between two concrete eco-blocks which comprise segmental retaining wall. Three interface conditions were considered : 1) direct contact of two blocks, 2) placing rubber pad between two blocks, 3) placing rubber pad and shear key between two blocks. According to shear tests, shear load-shear displacement relationship which was obtained from direct contact of two blocks was similar to elastic-perfectly plastic behavior. Ductile behavior of shear load-shear displacement relationship was observed for the interface condition of placing rubber pad. Apparent minimum shear capacities and apparent friction angles for the interface conditions of direct contact of two blocks, placing rubber pad between two blocks, placing rubber pad and shear key were 1.7 kN/m, $27.6^{\circ}$ and 4.2 kN/m, $26.2^{\circ}$ and 20.9 kN/m, $26.0^{\circ}$ respectively.