• Advances in concrete construction
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• 제5권4호
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• pp.331-343
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• 2017

In this study a polymer concrete, made up of natural aggregates and an orthophthalic polyester binder, reinforced with natural Alfa fibers has been studied. The results of flexural testing of unreinforced polymer concrete with different rates of charges (marble) showed that the concrete with 20% of marble is stronger and more rigid compared to other grades. Hence, a rate of 20% of marble powder is selected as the optimal value in the development of polymer concrete reinforced Alfa fibers. The fracture results of reinforced polymer concrete with 1 and 2 wt% of chopped untreated or treated Alfa fibers showed that treated Alfa (5% NaOH) fiber reinforced polymer concrete has higher fracture properties than other composites. We believe that this type of concrete provides a very promising alternative for the building industry seeking to achieve the objectives of sustainable development.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 춘계학술발표대회 논문집
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• pp.1.1-4
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• 1999

The toughening mechanism and fracture behavior of rubber/polymer composites were investigated with respect to two factors; (1) the composition ratio of polymers(PPO and PS which have a different chain flexibility) and (ii) the rubber particle size in PPO/PS blend system Izod impact test and fractographic observation of the fracture surface using scanning electron microscope were conducted, Finite element analysis were carried out to gain understanding of plastic deformation(shear yielding and crazing) of these materials.

• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.836-843
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• 2003

The polymer composites contain numerous internal boundaries and its structural elements have different responses and different resistances under the same service environment. Fatigue phenomenon is much more complex in composites than homogeneous materials. An understanding of the fracture behavior of polymer composite materials subjected to constant and cyclic loading is necessary for predicting the life time of structures fabricated with polymers. There is a need to acquire a better understanding of the fatigue performance and failure mechanisms of composites under such conditions. Therefore, in this study the analyses of fiber orientation and fracture mechanism for low cycle fatigue crack have been studied by SEM and LM for observing the ultrathin sections.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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• pp.171-177
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• 1995

Fracture mechanics does work for concrete, provided that one uses a proper, nonlinear form of fracture mechanics in which a finite nonlinear zone at fracture front is being considered. The fracture process zone is a region ahead of a traction-free crack, and the development of model of fracture process zone is most important to describe fracture phenomena in concrete. This paper is about fracture behavior of concrete cylinder under lateral pressure. Concrete cylinders were made of high strength normal connote, steel fiber reinforced concrete and steel fiber reinforced polymer-impregnated concrete and concrete and the fracture behavior such as cracking propagation and ultimate load are observed. The fracture process zone is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve and are implemented to the boundary element technique for the fracture analyses of the cylinders. The experimental results are compared with analysis results and tension-softening curves for the steel fiber reinforced concrete and steel fiber reinforced polymer-impregnated concrete are obtained by back analyses.

• 한국농공학회논문집
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• 제57권2호
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• pp.57-66
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• 2015

The purpose of this study was to improved the durability of a improved movable weir by replacing the improved movable weir's metal gate with a hybrid steel/glass fiber reinforced polymer composites panel gate. Because the metal gate of a improved movable weir is always in contact with water, its service life is shortened by corrosion. This study made four type of hybrid steel/glass fiber reinforced polymer composites panel gate with different steel gate surface deformation (control, sand blast, scratch and hole), flexural. Fracture properties tests were performed depending on the steel gate surface deformation. According to the test results, the flexural behavior, flexural strength and fracture properties of hybrid steel/glass fiber reinforced polymer composites panel gate was affected by the steel panel gate surface deformation. Also, the sand blast type hybrid steel/glass fiber reinforced polymer composites panel gate shows vastly superior flexural and fracture performance compared to other types.

• Composites Research
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• 제12권6호
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• pp.83-89
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• 1999

고무/폴리머 복합재료의 충격강도와 파괴 기구를 기지재의 체인 유연성을 나타내는 특성비 $C_{\infty}$와 강화고무의 입자 크기의 두 가지 관점에서 연구하였다. 본 연구에서 특성비는 PPO와 PS폴리머의 조성비에 의하여 조절하였다. 아이조드 충격 시험과 주사전자현미경에 의한 파단면 관찰을 수행하였다. 전단항복과 크래이징으로 대별되는 소성 변형 기구의 이해를 넓히기 위해 유한요소해석을 수행하였다. 전단항복은 폴리머의 유연성이 상대적으로 낮거나 고무의 입자 크기가 작은 경우에 잘 나타났다.

• 한국해양공학회지
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• 제10권4호
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• pp.51-57
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• 1996

A standard method for the evalution of the fracture toughness of the high polymer materials has not been fully developed in comparison with that for metallic materials, and has not yet established. In this paper, fracture toughness tests using polycarbonate specimens were carried out. The fracture thughness tests using polycabonate specimens were carried out. The fracture toughness of commercial polycarbonate were dependent on the specimen thickness. The specimen thickness is necessary above 8mm to obtain the valid $K_{IC}$. A cumulative counts were slightly dependent on specimen thickness.

• The Journal of Advanced Prosthodontics
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• 제14권5호
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• pp.315-323
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• 2022

PURPOSE. The purpose of this study was to investigate the effect of barium silicate filler contents on mechanical properties of resin nanoceramics (RNCs) for additive manufacturing (AM). MATERIALS AND METHODS. Additively manufactured RNC specimens were divided into 4 groups depending on the content of ceramic fillers and polymers: 0% barium silicate and 100% polymer (B0/P10, control group); 50% barium silicate and 50% polymer (B5/P5); 60% barium silicate and 40% polymer (B6/P4); 67% barium silicate and 33% polymer (B6.7/P3.3). The compressive strength (n = 15) and fracture toughness (n = 12) of the specimens were measured, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analyses were performed. Independent sample Kruskal-Wallis tests were performed on the compressive strength and fracture toughness test results, and the significance of each group was analyzed at the 95% confidence interval through post-tests using the Bonferroni's method. RESULTS. B6/P4 and B6.7/P3.3 exhibited much higher yield strength than B0/P10 and B5/P5 (P < .05). Compared to the control group (B0/P10), the other three groups exhibited higher ultimate strength (P < .05). The fracture toughness of B6/P4 and B6.7/P3.3 were similar (P > .05). The content of barium silicate and fracture toughness showed a positive correlation coefficient (R = 0.582). SEM and EDS analyses revealed the presence of an oval-shaped ceramic aggregate in B6/P4 specimens, whereas the ceramic filler and polymer substrate were homogeneously mixed in B6.7/P3.3. CONCLUSION. Increasing the ceramic filler content improves the mechanical properties, but it can be accompanied by a decrease in the flowability and the homogeneity of the slurry.

• 한국수소및신에너지학회논문집
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• 제32권1호
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• pp.86-91
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• 2021

In order to save the energy in vehicles using renewable energy, it is necessary to reduce the weight of parts with polymer matrix composites. Carbon nanotube (CNT) is the nano-scale reinforcement used to increase the interlaminar strength of fiber reinforced composites or enhance the fracture toughness of polymer. However, since the degree of improvement in mechanical properties varies according to the various experimental conditions such as shape of reinforcement, types of matrix and dispersion of reinforcement, research to find the optimal conditions is essentially needed. In this study, CNT/epoxy composites with different CNT concentration were fabricated under the same conditions, and the optimal CNT content (2 wt%) was found through Mode 1 fracture toughness test. Furthermore, through optical microscopy, it was confirmed that the fracture toughness was rather decreased due to the CNT aggregation when the CNT content exceeded 2 wt%.

• 자원환경지질
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• 제47권3호
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• pp.247-254
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• 2014

불균질한 자연균열 저류층에서 암체의 압축률은 매우 작은 값을 가지는 반면에 균열의 압축률은 상대적으로 큰 값을 갖는다. 균열의 압축률을 포함한 유효 압축률을 고려하지 않을 경우에는 균열의 간극 변화로 인한 공극 부피의 변화를 반영할 수 없기 때문에 정확한 오일 회수를 예측할 수 없다. 본 연구에서는 기존의 연구들에서 암체의 압축률만을 고려하여 오일 회수를 분석했던 것과 달리, 암체와 균열의 압축률을 모두 고려한 유효 압축률을 적용해서 오일 회수량을 분석하였다. 폴리머 공법에서 균열의 압축률이 폴리머의 주입에 미치는 영향을 이해하기 위해, 폴리머의 분자량, 농도, 주입속도에 따른 오일 회수량을 분석하였다. 유효 압축률을 고려할 경우 폴리머 분자량, 농도, 주입속도가 높아질수록 유효 압축률을 고려하지 않은 경우가 고려한 경우보다 누적 오일 생산량이 높게 나타났다. 또한 공저 압력의 경우에도 유효 압축률을 고려하지 않은 경우가 고려한 경우보다 빠르게 급감하여 오일 생산량에 영향을 주는 것을 확인할 수 있다.