• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.83-86
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• 2006

This study investigates engineering properties of concrete using recycled coarse aggregated manufactured by bar-crusher. Test showed that Bar-crusher(S) had more effective results at fresh state than cone-crusher(C) and impact-crusher(I). In case of specimens manufactured by S, increase of spindle velocity, incorporating ratio of recycled aggregate and maximum size of aggregate inclined fluidity. As for the hardened concrete, compressive strength of specimens by C or I exhibited lower value than that of S. In addition, specimens using recycled aggregate manufactured by 400rpm and 500rpm of spindle velocity showed less than 10% reduction rate of strength, which is not significant reducing value. It is found that 500rpm of the spindle velocity had the best strength performance, while 600rpm was the worst. Strength value of specimens decreased as incorporating ratio of recycled aggregate inclined, but the strength value of most specimens exhibited less than 10% of reducing rate, assuming favorable result, only at less than 25% incorporating ratio of recycled aggregate.

• 산업식품공학
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• 제21권1호
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• pp.36-41
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• 2017

The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from $1.2{\times}10^{-2}$ to $8.2{\times}10^{-3}$ and $6.4{\times}10^{-3}cm^2/s$ as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.163-172
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• 2022

Zinc-rich epoxy (ZRE) is used to overcome corrosion problems in reinforced concrete (RC) beams and coat steel rebars to protect them from humidity and chlorides. An extra coating layer of Sikadur-31 epoxy (SDE) is utilised to increase bond strength because the use of ZRE reduces the bond strength between concrete and steel rebars. However, the low melting point of SDE indicates that concrete specimens are vulnerable to fire. An experimental investigation on flexural performance of RC beams incorporating ZRE-SDE coating of steel rebars that were destroyed by fire is performed in this study. Twenty beams of five concrete mixes with different cementitious contents were tested to compare fire exposure for coated and uncoated rebars of the same beams at room temperature and determine the optimal cementitious content. Scanning electron microscopy (SEM) was also applied to investigate characteristics of fired mixture samples. Results showed that the use of SDE-ZRE at room temperature improves flexural strengths of the five mixes compared with uncoated rebars with percentages ranging from 8.5% to 12.3%. All beams with SDE-ZRE lost approximately 50% of their flexural strength due to firing. Moreover, the mix incorporating SF (silica fume) of 15% and cement content of 400 kg/m³ introduces optimum behaviour compared with other mixes. All results were supported and verified by the SEM analysis and compressive strength of cubic specimens of the same mixes.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.431-441
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• 2023

The aim of this paper is to present a new sustainable ternary and quaternary binder by partially replacing ordinary Portland cement (OPC) with different percentages of supplementary cementitious materials. The motivation is to reduce our dependency on OPC to reduce CO₂ emission and carbon foot print. As the main substitute for the OPC, siliceous fly ash was used. Moreover, silica fume and nanosilica were also used. During examinations the main mechanical parameters of concrete composites, i.e., compressive strength (f_cm) and splitting tensile strength (f_ctm) were assed. The microstructure of these materials was also analysed. It was found that the concrete incorporating pozzolanic materials is characterized by a well-developed structure and has high values of mechanical parameters. The quaternary concrete containing: 80% OPC, 5% FA, 10% SF, and 5% nS have shown the best results in terms of good strength parameters as well as the most favourable microstructure, whereas the worst mechanical parameters with microstructure containing microcracks at phase interfaces were characterized by concrete with more content of FA additive in the concrete mix, i.e., 15%. Nevertheless, all concretes made on quaternary binders had better parameters than the reference one. It can be stated that sustainable concrete incorporating pozzolanic materials could be good substitute of ordinary concretes.

• 교통기술과정책
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• 제10권6호
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• pp.52-63
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• 2013

• 대한교통학회:학술대회논문집
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• 대한교통학회 1994년도 제26회 학술발표회
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• pp.5-23
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• 1994

• 대한간호
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• 제20권1호통권109호
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• pp.22-23
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• 1981

• 전산구조공학
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• 제22권6호
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• pp.80-86
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• 2009

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 춘계학술발표대회 요약집
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• pp.195.1-195.1
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• 2003

• 대한교통학회:학술대회논문집
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• 대한교통학회 2007년도 제56회 학술발표회논문집
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• pp.485-494
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• 2007