• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.269-274
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• 1998

In this study, to increase fluidity and resistance of segregation of materials, the effect of each of the materials, which have effects on high performance concrete from investigating the properties of strength and drying shrinkage of high performance concrete made by the basic mix proportion used fly-ash and ground granulated blast-furnace slag after hardening, has been checked. According to the experimental results, fluidity on W/C = 34% was satisfied within slump-flow 65$\pm$ 5cm and U-type self-compactability difference 5cm. On the properties of strength, high performance concrete produced compressive strength over 400kg/$\textrm{cm}^2$ in 28days when powder was replaced by 40% of fly-ash and 60% of ground granulated blast-furnace slag. And compressive strength was taken over 600kg/$\textrm{cm}^2$ equal to non-replacement in 91days. Also, the length change of concrete with the addition of fly-ash was smaller than that without it. Therefore, it may be effective on the decrease of drying shrinkage volume.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.307-312
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• 1998

Recently the study on high flowing concrete which has high workability and Self-compacting is being proceeded actively in the university and corporative laboratory. There are some cases that has been applied to the field. This high flowing concrete has higher fluidity and segregation resistance than Plain of flowing concrete. And it is being focused as a remarkable know-how which can make high-quality concrete and reduction effect of labor force. This properties of high flowing concrete are influenced by the relationship of several factors; binder content, water binder ratio and unit water content. It is the aim of this study to propose reference data at mix design of high flowing concrete, after comparing and analyzing the fluidity and strength properties of high flowing concrete according to water binder content ratio and unit water content.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.275-280
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• 1998

In this study, to increase fluidity and resistance of segregation of materials, the effect of each of the materials, which have effects on high performance concrete from investigating the properties of strength and drying shrinkage of high performance concrete made by the basic mix proportion used fly-ash and ground granulated blast-furnace slag after hardening, has been checked. By the results of this experiment, fluidity on W/C=34% was satisfied within slump-flow 65$\pm$5cm and U-type self-compacting difference 5cm. On the properties of strength, high performance concrete produced compressive strength over 400kg/$\textrm{cm}^2$ in 28days when powder was replaced by 40% of fly-ash and 60% of ground granulated blast-furnace slag. And compressive strength was taken over 600kg/$\textrm{cm}^2$ equal to non-replacement in 91days. Also, the length change of concrete with the addition of fly-ash was smaller than that without it. Therefore, it may be effective on the decrease of drying shrinkage volume.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.103-109
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• 2007

In this study, the rheological properties of cement pastes containing blastfurnace slag of different fineness were investigated. The fluidity of cement pastes with low Blaine value blastfurnace slag was increased with decreasing the plastic viscosity and the yield stress of pastes. And the optimum dosage of polycarboxylate type superplasticizer to the cement pastes was confirmed according to the fineness and the replacement ratio of blastfurnace slag. All cement pastes showed the thixotropy behavior. And also it was formed that the segregation range of cement pastes was occurred below $10D/cm^2$ of the yield stress and below 350 cPs of the plastic viscosity by the coaxial cylinder viscometer.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.388-391
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• 2004

This research investigates how the fineness modulus of fine aggregates and the grain shape of coarse aggregates affects flow characteristics, packing characteristics and compressive strength characteristic. The experimental results, show that increase of the fine aggregate's fineness modulus improved concrete flow, but filling ability was high at over KS regulation extent due to segregation phenomena. It is considered that the improvement of 0.1 spherical rate was effective to concrete fluidity elevation by reducing about $6\%$ of fine aggregate ratio displays which the smallest gap rate of aggregate. Compressive strength was increased to about 0.6MPa everytime F.M. 0.1 of fine aggregate fineness is increased. However, it was decreased to about 9MPa at F.M. 3.5 compared to F.M. 3.0.

• Computers and Concrete
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• v.20 no.3
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• pp.297-310
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• 2017

A CFD software was used to simulate free surface flow of SCC in the T-Box test. In total, seven simulations were developed to study the effect of rheological parameters on the non-restricted flow performance of SCC in both horizontal and vertical directions. Different suspending fluids having five plastic viscosity values between 10 and 50 Pa.s, three yield stress values between 14 and 75 Pa, one density of $2500kg/m^3$, and one shear elasticity modulus of 100 Pa were considered for suspension of 178 spherical particles of 20-mm diameter and $2500kg/m^3$ density. The results of the simulations are found to correlate well to changes in rheological parameters of the suspending fluid. Plastic viscosity was shown to be the most dominant parameter affecting flowability and dynamic stability compared to the yield stress. A new approach was proposed to evaluate performability of SCC based on a trade-off between flowability and dynamic stability.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.407-410
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• 2005

This research investigates experimentally an effect on the properties of the combined high flowing concrete by mix design factors. The purpose of this study is to determine the optimum mix proportion of the combined high flowing concrete having good flowability, viscosity, no-segregation and design strength(40.0MPa). For this purpose, trial mixings used belite cement+lime stone powder(LSP) are tested by mix design factors including water-cement ratio($47.9\~54.0\%$), fine aggregate volume ratio($41\~45\%$) and coarse aggregate volume ratio($41\~45\%$). As test results of this study, the optimum mix proportion for the combined high flowing concrete is as followings. Water-cement ratio $51.0\%$, fine aggregate volume ratio $43{\pm}1\%$ and coarse aggregate volume ratio $0.30{\pm}0.05m^3/m^3$ and replacement ratio of LSP $42.7\%$.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.399-421
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• 1996

(1) The solute distribution mechanism was analyzed for the Si0.95Ge0.05 single crystal fiber by u-PD method. (2) The steady-state solutions were obtained for the molten zone and the capillary zone. (3) The effect of the convection in the molten zone on partitioning was not significant for many cases. (4) Intermediate transient rise of Ge was shown by the sudden change of the growth velocity or molten zone height. (5) Periodic compositional modulation can be designed by using the intermediate transient.

• Journal of Korea Foundry Society
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• v.29 no.2
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• pp.78-85
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• 2009

Functionally graded microstructure of centrifugal cast Al-Si alloy, especially distribution of primary Si particles according to the changes of melt pouring temperature and rotation frequency was investigated by numerical simulation. Moving velocity of Si particles increased as the melt pouring temperature and rotational frequency of mold increased. Therefore, segregation tendency of primary Si particles toward inner side of cylindrical sample increased as the melt pouring temperature and rotational frequency of mold increased. Rich distribution region of particles was located at 0.9, 0.7, 0.4 mm from inner surface of cylindrical sample under the centrifugal cast condition of $750^{\circ}C$ melt pouring temperature and 1500, 2000 and 2500 rpm mold rotational frequencies, respectively, by numerical simulation.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.89-94
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• 2003

In this research, the physical properties of self compacting concrete using ground granulated blast furnace slag and fly ash as a part of cement were investigated. Concrete using ground granulated blast furnace slag and fly ash was prepared with various ground granulated blast furnace slag(30-50 volume %) and fly ash(10-20 volume %) replacement for cement. The effect of each of the materals, which have effects on self compacting concrete made by the basic mix proportion used granulated blast furnace slag and fly ash after hardening, has been checked. The workability, flowing characteristics, resistance of segregation of materals, air content, and compressive strength of concrete using ground granulated blast furnace slag and fly ash were tested and the results were compared with those of ordinary portland cement concrete. In the experiment, we acquired satisfactory results at the point of flowing characteristics and strengths of concrete using ground granulated blast furnace and slag fly ash within the replacement ratio of 65%