• Geomechanics and Engineering
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• v.5 no.6
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• pp.565-574
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• 2013

Extensive study was carried out on Clay expansive soil. This soil was silty clay and can be classified as CH. The degree of expansion was found to range from low to medium depending on the free swell and swell pressure tests. The research investigated the effect of using cement dust on swelling potential, Atterberg Limit, linear shrinkage, and mineralogical composition of expansive soil. The results showed that the swelling potential, plasticity index, linear shrinkage, and clay minerals decrease with increasing cement dust percentage. The cement dust accumulates in huge amounts as a side product in cement factories, and the disposal of this fine dust is very difficult and poses an environmental threat.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.173-179
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• 2020

Let X be a compact space and Λ a finite index set. We deal with dynamical properties of iterated function systems on X. For an iterated function system 𝓕 on X, we prove that 𝓕 is c-expansive if and only if 𝓕^k is also c-expansive for each k ∈ ℕ. Furthermore we prove that the c-expansiveness of 𝓕 is equivalent to the original expansiveness of the shift map of it.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.117-120
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• 2004

Up to now, many researches have been performed md verified that many properties of concrete can be improved by using mineral admixtures such as blast furnace slag, silica fume, and expansive admixture. But it is not clear whether there is any need for entraining air to make a high strength concrete using expansive admixture and mineral admixtures to insure enough freeze-thaw resistance. this paper presents the strength and durability properties of high strength concrete using expasive admixtures and industrial by-products. It was observed from the test results that very high strength concrete$(W/B=20\%)$ is not needed to be air entrained and high strength concrete$(W/B=30\%)$ using expansive admixture and mineral admixtures is needed to be entrained $2\~4\%$ air.

• Communications of the Korean Mathematical Society
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• v.19 no.4
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• pp.759-764
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• 2004

Let X = {a} ${\cup}$ {$a_{i}$ ${$\mid$}$i $\in$ N} be a subspace of Euclidean space $E^2$ such that $lim_{{i}{\longrightarrow}{$\infty}}a_{i}$ = a and $a_{i}\;{\neq}\;a_{j}$ for $i{\neq}j$. Then it is well known that the space X has no expansive homeomorphisms with the shadowing property. In this paper we show that the set of all expansive homeomorphisms with the shadowing property on the space Y is dense in the space H(Y) of all homeomorphisms on Y, where Y = {a, b} ${\cup}$ {$a_{i}{$\mid$}i{\in}Z$} is a subspace of $E^2$ such that $lim_{i}$-$\infty$ $a_{i}$ = b and $lim_{{i}{\longrightarrow}{$\infty}}a_{i}$ = a with the following properties; $a_{i}{\neq}a_{j}$ for $i{\neq}j$ and $a{\neq}b$.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.167-174
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• 1998

• Kyungpook Mathematical Journal
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• v.52 no.2
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• pp.155-165
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• 2012

In this paper, we have studied some fixed point theorems on complete G-metric spaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4884-4890
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• 2012

In this dissertation, the shrinkage and durability of shotcrete were examined. Analysis and comparison of shrinkage against the strength of shotcrete was investigated after performing actual shotcrete shooting for each mix of different percentage of expansive agent. The research on restrained shrinkage with different percentages of expansive agent used (3%, 7%, 11% and 15%) shows that the maximum shrinkage in all samples occurred in between 13-15 hrs after shotcrete shooting. And it is noticed that increasing the percentage of expansive agent can lower the shrinkage. And hence, the 15% of expansive agent not only lowered the shrinkage But it also lowered the strength.

• Geomechanics and Engineering
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• v.29 no.1
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• pp.91-97
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• 2022

The cohesive non-swelling soil (CNS) cushion technology has been widely applied in the subgrade and slope improvement at expansive soil regions. However, the mechanism of the inhibition effect of the CNS layer on expansive soil (ES) has not been fully understood. We performed four outdoor model tests to further understand the inhibition effect, including different kinds of upper layer and thickness, under the unidirectional seepage condition. The swelling deformation, soil pressure, and electrical resistivity were constantly monitored during the saturation process. It is found that when a CNS layer covered the ES layer, the swelling deformation and electrical resistivity of the ES layer decreased significantly, especially the upper part. The inhibition effect of the CNS layer increases with the increase of CNS thickness. The distribution of vertical and lateral soil pressure also changed with the covering of a CNS layer. The electrical resistivity can be an effective index to describe the swelling deformation of ES layer and analyze the inhibition effect of the CNS layer. Overall, the CNS deadweight and the ion migration are the major factors that inhibit the swelling deformation of expansive soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.787-794
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• 2006

Generally, high performance concrete has characteristics such as low water-cementitious material ratio, lots of unit binder powder, thus the heat of hydration, autogenous shrinkage are tend to be increased. This study is to investigated the effect of the expansive additive and shrinkage reducing agent on the shrinkage properties of high performance concrete as a study to develop the reduction technology of the concrete shrinkage. Test results showed that the expansive additive and shrinkage reducing agent were effective the reduction of shrinkage of high performance concrete. Especially, the using method in combination with expansive additive and shrinkage reducing agent was more effective than the separately using method of that. Also, it analyzed that the combination of expansive additive of 5% and shrinkage reducing agent of 1% was the most suitable mixture, considering to the fluidity, strength and shrinkage properties.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.617-624
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• 2010

This paper reports on a comprehensive study on the mechanical properties of expansive fiber-reinforced strainhardening cement composite (SHCC) materials containing various replacement levels (0, 8, 10, 12 and 14%) of an expansive admixture and 1.5% polyethylene (PE) fibers volume fraction. A number of experimental tests were conducted to investigate shrinkage, compressive strength, flexural strength, and direct tension behavior. Test results show that as expected, the different replacement levels of an expansive admixture have an important effect on the evolution of the free shrinkage of SHCC with a rich mixture. At the volume fraction of 1.5%, PE fibers in normal SHCC reduce free shrinkage deformation by about 30% in comparison to plain mortar. The replacement of an expansive admixture in SHCC material has led the SHCC to a better initial cracking behavior. Enhanced cracking tendency improved mechanical properties of SHCC materials with rich mixtures. Note that an increase in the replacement of expansive admixture from 10% to 14% does not lead to a significant improvement for mechanical properties; this implies that the replacement of 10% expansive admixture is sufficient.