• 대한화학회지
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• 제49권4호
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• pp.399-406
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• 2005

• 공업화학
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• 제16권6호
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• pp.842-847
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• 2005

니트릴고무(NBR) 신재와 작업현장에서 나온 스크랩을 고온 전단분쇄기술로 분말화한 재료(재생 NBR)를 다양한 혼합비로 블렌드물을 제조하고, 재생재료의 함량에 따른 블렌드물의 가황 거동, 물리적 특성의 변화를 조사하였다. 또한, 열 및 각종 유체에 대한 각 블렌드물의 저항성을 물리적 방법으로 조사하였다. 신재 NBR에 고온 전단 분쇄기술로 제조한 재생NBR을 0~50 phr의 함량으로 블렌드하여 가황거동 및 물리적 특성을 측정한 결과, 가황 거동은 점도가 증가하고 스코치 시간은 감소하였으며, 내열 및 유체특성은 향상되었다.

• Elastomers and Composites
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• 제40권2호
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• pp.104-111
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• 2005

고가이면서 고기능성 특수고무의 한 종류인 불소고무(Fluororubber) 신재와 폐 불소고무를 고온 전단분쇄기술로 분말화한 재료(recycled FKM)를 다양한 혼합비로 블렌드물을 제조하고 재생재료의 함량에 따른 블렌드물의 가황 특성, 물리적 성질의 변화를 조사하였으며, 이 블렌드물의 열 및 연료에 대한 물성변화율을 측정하였다. 불소고무(FKM) 신재에 고온 전단분쇄 기술로 제조한 재생 불소재료를 $0{\sim}50$ phr까지 블렌드하여 각종 물성을 측정한 결과, 재생불소고무의 배합조성이 30 phr인 블렌드물이 저가이면서도 분산성, 내열성 및 내연료유성의 물성변화율이 가장 작은 배합구성으로 나타났다.

• Structural Engineering and Mechanics
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• 제48권1호
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• pp.17-39
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• 2013

In the present paper, a coaxial rotating smeared crack model is proposed for mass concrete in three-dimensional space. The model is capable of applying both the constant and variable shear transfer coefficients in the cracking process. The model considers an advanced yield function for concrete failure under both static and dynamic loadings and calculates cracking or crushing of concrete taking into account the fracture energy effects. The model was utilized on Koyna Dam using finite element technique. Dam-water and dam-foundation interactions were considered in dynamic analysis. The behavior of dam was studied for different shear transfer coefficients considering/neglecting fracture energy effects. The results were extracted at crest displacement and crack profile within the dam body. The results show the importance of both shear transfer coefficient and the fracture energy in seismic analysis of concrete dams under high hydrostatic pressure.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 가을 학술발표회 논문집
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• pp.113-120
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• 1994

Large Concrete Panel Structures behave quite differently from frame or monolithic shear wall structures because of the weakness of Joint in stiffness and strength. The joint experiences large deformation such as shear-slip in vertical and horizontal joint and rocking and crushing in horizontal joint because of localized stress concentration, but the wall panels behave elastically under cyclic loads. In order to describe the nonlinear behavior of the joint in the analysis of PC structures, different analysis technique from that of RC structures is needed. In this paper, for analysis of large concrete panel subassemblage subjected to cyclic loads, the wall panels are idealized by elastic finite elements, and the joints by nonlinear spring elements with various load-deflection relationship. The analytical results are compared with the experimental results on the strength, stiffness, energy dissipation and lateral drift, and the effectiveness of this computer analysis modelling technique is checked.

• Structural Engineering and Mechanics
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• 제36권1호
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• pp.57-78
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• 2010

A novel flexibility-based 1D element that captures the material nonlinearity and second order P-$\Delta$ effects within a reinforced concrete frame member is developed. The formulation is developed for 2D planar frames in the modified fiber element framework but can readily be extended to 3D cases. The nonlinear behavior of concrete including cracking and crushing is taken into account through a modified hypo-elastic model. A parabolic and a constant shear stress distribution are used at section level to couple the normal and tangential tractions at material level. The lack of objectivity due to softening of concrete is addressed and objectivity of the response at the material level is attained by using a technique derived from the crack band approach. Finally the efficiency and accuracy of the formulation is compared with experimental results and is demonstrated by some numerical examples.

• Structural Engineering and Mechanics
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• 제67권1호
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• pp.1-8
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• 2018

Shake table tests performed on five 1:3 reduced scale two story RC moment resisting frames having construction defects, have shown severe joint damageability in deficient RC frames, resulting in joint panels' cover spalling and core concrete crushing. Haunch retrofitting technique was adopted herein to upgrade the seismic resistance of the deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frames' seismic response parameters are calculated and compared to evaluate the viability of haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure's overstrength. The retrofitting increased response modification factor R by 60% to 100%. Further, the input excitation PGA was correlated with the lateral roof displacement to derive structure response curve that have shown significant resistance of retrofitted models against input excitations. The technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events, hence, promising for seismic risk mitigation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.225-228
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• 2008

철근콘크리트 구조물을 해석하는 경우, 하중조건 및 이들 하중의 증가에 따라 나타나게 되는 상이한 거동 특성들 즉, 인장균열, 압축파괴, 다축상태일 때의 강도의 증가, 전단파괴 시의 취성적 파괴특성 등을 반드시 고려해야만 한다. 유한요소법에 의한 해석적 평가 시, 최대하중 이후에는 요소크기에 따라 상이한 구조응답을 나타내는 요소의존적인 응답결과를 보인다. 본 연구에서는 이러한 요소의존성을 극복하기 위한 연구결과들 중 하나인 적분형 비국소화 모델을 이용하여 전력구 모형 실험체의 파괴거동을 해석하였다. 실험결과와 해석결과를 비교하여 적분형 비국소 모델의 신뢰성과 타당성을 검토하는 것을 목적으로 한다.