• 대한수학회지
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• 제55권3호
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• pp.593-604
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• 2018

Recently, a new version of expansiveness which is closely attached to some certain weak version of hyperbolicity was given for $C^1$ vector fields as following: a $C^1$ vector field X will be called rescaling expansive on a compact invariant set ${\Lambda}$ of X if for any ${\epsilon}$ > 0 there is ${\delta}$ > 0 such that, for any $x,\;y{\in}{\Lambda}$ and any time reparametrization ${\theta}:{\mathbb{R}}{\rightarrow}{\mathbb{R}}$, if $d({\varphi}_t(x),\,{\varphi}_{{\theta}(t)}(y)){\leq}{\delta}{\parallel}X({\varphi}_t(x)){\parallel}$ for all $t{\in}{\mathbb{R}}$, then ${\varphi}_{{\theta}(t)}(y){\in}{\varphi}_{(-{\epsilon},{\epsilon})}({\varphi}_t(x))$ for all $t{\in}{\mathbb{R}}$. In this paper, some equivalent definitions for rescaled expansiveness are given.

• 한국주조공학회지
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• 제17권1호
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• pp.36-50
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• 1997

Invar-type austenitic cast irons are being used as low thermal expansive materials because of its good low thermal expansion characteristics and castability despite its low hardness. The effects of alloying elements such as Cr, Ti, V, and Mo on hardness and linear thermal expansion coefficient of the invar-type austenitic cast irons were investigated. A combined use of V and Mo addition was found to be the most effective for the improvement of hardness without causing an increase in the thermal expansion coefficient. With a combined addition of 4.6wt%V and 3.8wt%Mo, the hardness increased up to 180HB and the thermal expansion coefficient was kept at a relatively low value of $4.6{\times}10^{-6}/^{\circ}C$ in the temperature range from room to $250^{\circ}C$.

• 충청수학회지
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• 제7권1호
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• pp.199-209
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• 1994

In this paper, we show that a persistent dynamical system is structurally stable with respect to $E_{\alpha}$(X) for every ${\alpha}$ > 0 if it is expansive. Also, we prove that a homeomorphism$ f:{\Omega}(f){\rightarrow}{\Omega}(f)$ has the semi-shadowing property then so does $f:\overline{C(f)}{\rightarrow}\overline{C(f)}$.

• 한국세라믹학회지
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• 제42권7호
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• pp.483-489
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• 2005

For the raw materials of 3CaO$\cdot$3Al$_{2}$O$_{3}$ $\cdot$CaSO$_{4}$(CSA) clinker manufacturing, the applications of industrial wastes such as waste shell, spent oil-refining catalyst and desulfurized gypsum were examined. The c1inkerbility of the raw mix and the behaviour of formation of clinker minerals were studied and then some hydraulic properties of cements containing the clinker were also investigated. By virtue of the high reactivity of thermally decomposed raw materials, CSA clinkers were obtained at relatively low temperature of 1250$^{\circ}C$ and thus oil-refining catalysts were more desirable than aluminium hydroxide as an aluminous raw material. The expansive cement samples showed somewhat lower flow value than that of OPC, but their compressive strengths were developed earlier and higher than that of OPC due to formation of ettringite in the early hydration time, which indicated the possibility of practical use of low-cost CSA clinker using industrial wastes only.

• 충청수학회지
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• 제32권1호
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• pp.157-164
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• 2019

In this article, we study expansiveness of the shift maps on orbital inverse limit spaces which consist of two cross bonding mappings. On orbital inverse limit systems, horizontal directions express inverse limit systems and vertical directions mean orbits based on horizontal axes. We characterize the c-expansiveness of functions on orbital spaces. We also prove that the c-expansiveness of the functions is equivalent to the expansiveness of the shift maps on orbital inverse limit spaces.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.123.2-123
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• 2000

• Advances in Computational Design
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• 제5권1호
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• pp.1-11
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• 2020

Soil is the fundamental element in the construction process. Soil problems affect the safety of the structures, even so the high quality of the structures and so, bad soil found the structures will affect the lifetime or even destroy the structures built on it. Therefore, the study of soil is an important step in the construction process and the investigation of the most effective characteristics of a special kind of soil (shale soil), i.e. Atterberg limits, swelling pressure, swelling potential and unconfined compression strength, are the most effective soil properties. A big projects will be constructed in new urban extension areas with expansive shale soils, like at Al-Kawamil and new Akhmim shale soils which associated with soil problems, treatment system should be used to ensure the stability of the soil under the structures foundations one of the most effective methods is by adding lime solution to the soil by specific quantities, which affect on the properties of the shale soil by decreasing the swelling and increasing the compressive strength of the treatment soils. Experimenting with the soil added to the lime, it was found that the addition of lime solution 6% improve c j the properties of the soil. The results of the tests showed the high effectiveness of using lime in the treatment of Al-Kawamil soil

• 국제지역연구
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• 제20권1호
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• pp.105-125
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• 2016

일본은 21세기에 들어와서 경기침체와 디플레이션을 극복하기 위하여 확산적 화폐금융정책을 실시하였으며, 최근 아베정부는 무제한적으로 화폐공급을 증가시키고 있다. 그러나 이와 같은 정책의 효과는 아직 뚜렷이 나타나지 않고 있다. 본 연구의 목적은 2001년 이후 일본금융정책의 효과를 검증하는데 있다. 이를 위하여, 일본에서는 1990년 이후 버블형성과 붕괴이후 민간경제주체의 기대형성 과정이 변하고 있다는 사실에 기인하여, 기대가설을 내포하고 있는 거시모형을 설정하였다. 본 연구에서 사용된 거시모형은 통화량이 환율에 미치는 영향을 포함하였으며, 이를 IVM와 VAR를 이용하여 통계적으로 분석하였다. 통계분석 결과는 다음과 같다. 화폐금융정책의 효과는 2001.01-2015.03 기간에서 1985.01-1994.04.기간보다 낮아졌으며 효과가 미치는 기간도 짧아지고 있다. 이는 버블형성과 붕괴를 경험한 일본 민간경제주체가 더 이상 화폐금융정책의 효과를 믿지 않고 있기 때문인 것으로 판단된다. 통화량의 증가에도 불구하고 총수요는 영향을 받지 않고 있으며, 기대하지 못한 환율의 변화는 순수출을 증가시키고 있지만 통화 증가가 환율의 기대오차에 영향을 주지 못하고 있는 것으로 판단된다. 본 연구의 결과가 금융정책에서 의미하는 바는 중요하다고 할 수 있다. 일본의 버블형성과 붕괴, 그 후의 금융정책의 실패 등은 민간경제주체의 정책에 대한 신뢰를 변화시켰고, 화폐금융정책의 효과는 점차 낮아지고 있으며 불확실성은 커지고 있다. 확산적 화폐금융정책은 효과가 미흡할 경우 그 정책에 내재해 있는 위험성은 높아지므로 정책실시에 보다 신중한 결정이 요구된다. 또한 정부부채를 이용하는 재정정책을 배합하는 방향도 고려할 필요가 있다. 문제는 일본 정부부채 비율이 250%에 달한 것인데, 그렇다고 해서 재정정책을 사용하지 못한다는 근거는 없으므로, 이에 대한 또 다른 연구가 요구되는 시점이다.

• 한국안전학회지
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• 제25권3호
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• pp.28-33
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• 2010

Ni alloy steel is able to use during long time because of good acid and corrosion resistance. So, it's research has focused on developing the alternative alloy which is economically feasible. Recently, consumption of Kovar steel is gradually increased in field of the jet engine and the gas turbine because of its low thermal expansive characteristics. The specimens of Kovar steel(29%Ni-17%Co) contain 0.00%C, 0.03%C, 0.06%C, 0.10%C and 0.20%C, respectively. Ingots are manufactured by VIM(vacuum induction melting furnace) and then specimens are made by automatic hot rolling after heat treatment. Strength of Kovar steel according to carbon contents is estimated by hardness, tensile and impact test. Hardness of the 0.20%C specimen is more improved approximately 14.4% than one of base metal. Its strength increases 32.4% of a base metal, and its impact energy is also enhance 11.5%.

• 대한수학회논문집
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• 제33권4호
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• pp.1271-1284
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• 2018

In this paper, we establish strong convergence of the modified Ishikawa iterates of an asymptotically non expansive self-mapping of a nonempty closed bounded and convex subset of a uniformly convex Banach space under a variety of new control conditions.