• 한국수학교육학회지시리즈B:순수및응용수학
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• 제18권4호
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• pp.285-291
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• 2011

In this paper, we show that if a transitive set ${\Lambda}$ is $C^1$-stably expansive, then ${\Lambda}$ admits a dominated splitting.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.175-180
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• 1999

The heating system of korea apartment house is called Ondol. The surface finishing mortar of this floor system typically used the cement based mortar, where the surface finishing mortar easily appears the crack. To order to crack control, the cement that added expansive additive used to reducing dry-shrinkage. For the surface finishing mortar, the types of shrinkage is known as plastic shrinkage, dry-shrinkage and autogenous This experimental study is to investigate the difference on dry-shrinkage of the cement that added expansive additives and OPC. The test method is varied the ration of water/cement (W/C) and the ratio of sand/cement(S/C). For OPC, The increase of the ratio of S/C is reduced dry-shirnkage but for the cement that added expansive additives, the increase of the ratio of S/C is augmented dry-shrinkage For OPC, The increase of the ratio of W/C is augmented dry-shrinkage but for the cement that added expensive, the increased of the ratio of W/C is reduced dry-shrinkage.

• 한국세라믹학회지
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• 제37권4호
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• pp.388-394
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• 2000

The C4A3S clinker was prepared by the solid-state reaction. The mixture of raw materials; calcite, kaoline and gypsum, was fired at 135$0^{\circ}C$ for 1hr and cooled rapidly in air. C4A3S type expansive was made with C4A3S clinker, CaO and CaSO4. The cement replaced by 10 wt.% C4A3S type expansive was investigated by the measurement of the strength(compressive, tensile, flexural) and length change at various curing conditions. Hydration products were mainly ettringite, monosulfate and Ca(OH)2. The densification and the expansion due to the formation of ettringite during the hydration increased strength and reduced the drying shrinkage of hardened cement.

• 충청수학회지
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• 제28권3호
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• pp.391-396
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• 2015

$C^1$-generically, if a transitive diffeomorphism f is periodically expansive, then it is hyperbolic.

• Nonlinear Functional Analysis and Applications
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• 제27권2호
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• pp.271-287
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• 2022

In this article, we shall prove a common fixed point theorem for two weakly compatible self-maps 𝒫 and 𝔔 on a dislocated metric space (M, d^*) satisfying the following ξ-weakly expansive condition: d^*(𝒫c, 𝒫d) ≥ d^* (𝔔c, 𝔔d) + ξ(∧(𝔔c, 𝔔d)), ∀ c, d ∈ M, where $${\wedge}(Qc,\;Qd)=max\{d^*(Qc,\;Qd),\;d^*(Qc,\;\mathcal{P}c),\;d^*(Qd,\;\mathcal{P}d),\;\frac{d^*(Qc,\;\mathcal{P}c){\cdot}d^*(Qd,\;\mathcal{P}d)}{1+d^*(Qc,\;Qd)},\;\frac{d^*(Qc,\;\mathcal{P}c){\cdot}d^*(Qd,\;\mathcal{P}d)}{1+d^*(\mathcal{P}c,\;\mathcal{P}d)}\}$$. Also, we have proved common fixed point theorems for the above mentioned weakly compatible self-maps along with E.A. property and (CLR) property. An illustrative example is also provided to support our results.

• 대한수학회논문집
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• 제35권1호
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• pp.287-300
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• 2020

We introduce and study notions of expansivity, topological stability and persistence for Borel measures with respect to time varying bi-measurable maps on metric spaces. We prove that on Mandelkern locally compact metric spaces expansive persistent measures are topologically stable in the class of all time varying homeomorphisms.

• 충청수학회지
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• 제36권3호
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• pp.171-180
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• 2023

Investigating local dynamics requires precise control to effectively manage the subtle differences that distinguish it from global dynamics. This paper aims to study the localized perspective of the recently proposed continuum-wise expansive measures [13]. Let f : M → M be a diffeomorphism on a closed smooth manifold M and let p be a hyperbolic periodic point of f. We prove that if the homoclinic class H_f (p) of f associated to p is C¹-robustly measure continuum-wise expansive then it is hyperbolic.

• 한국건축시공학회지
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• 제10권4호
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• pp.113-122
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• 2010

In this study, 150MPa ultra-high-strength concrete was manufactured, and its performance was reviewed. As technically meaningful autogenous shrinkage reportedly occurs at a W/B ratio of 40% or less, although it occurs in all concrete regardless of the W/B ratio, the effects of the use of expansive admixture and shrinkage reducer, or of the friction and restraint of forms that may result in the effective reduction of autogenous shrinkage, were reviewed. As a result, considering the flow and strength characteristics, it was found that the slump flow time was shorter with expansive admixture, and shortest with shrinkage reducer. All specimens with $30kg/m^3$ expansive admixture showed high strength at early material age. Their strength decreased due to the expansion cracks when there was excessive use of expansive admixture, and the use of shrinkage reducer did not influence the change in the strength according to the material age. The expansive admixture had a shrinkage reduction effect of 80%, while the shrinkage reducer had a shrinkage reduction effect of 30%, indicating that the expansive admixture had a stronger effect. It seems that mixing the two will have a synergistic effect. The shrinkage reduction rate was highest when the W/B ratio was 20%. The form suppressed the expansion and shrinkage at the early period, and the demolding time did not significantly influence the shrinkage. The results of the study showed that the excessive addition of expansive admixture leads to expansion cracks, and the expansive admixture and shrinkage reducer have the highest shrinkage reduction effect when they are mixed.

• 충청수학회지
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• 제28권3호
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• pp.451-463
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• 2015

A continuous and non-decreasing function ${\psi}$ and another continuous function ${\phi}$ with ${\phi}(z)=0{\Leftrightarrow}z=0$ defined on $\mathbb{C}^+=\{x+yi:x,y{\geq}0\}$ are introduced, the ${\psi}-{\phi}$-contractive or expansive type conditions are considered, and the existence theorems of common fixed points for two mappings defined on a complex valued metric space are obtained. Also, Banach contraction principle and a fixed point theorem for a I-expansive type mapping are given on complex valued metric spaces.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.243-248
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• 2001

The objective of this study is to investigate the thermal conductivity of cement mortar for apartment housing floor using expansive admixture, copper fiber, cower lathe, hollowed aluminum plate. According to test results, temperature at point (a) located above heating pipe does not show significant variation with age, and temperature at (b), which is located at the finishing surface above heating pipe, and temperature at (c), which is located at center surface between heating pipe has remarkable change. Temperature distribution sat (b) are in order for, structure containing copper fiber>plain structure>structure containing hollowed aluminum plate>structure containing expansive admixture. Temperature distribution, shows high tendency in order for, structure containing copper fiber>structure containing copper lathe>structure containing hollowed aluminum plate>plain structure>structure containing expansive admixture. (a) estimation of temperature distribution is determined with the variation of temperature between (b) point and (c) point during 60 minutes heating.