• International Journal of Concrete Structures and Materials
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• 제9권4호
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• pp.453-462
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• 2015

A critical review on existing creep theories in calcium-silicate-hydrate (C-S-H) is presented with an emphasis on several fundamental questions (e.g. the roles of water, relative humidity, temperature, atomic ordering of C-S-H). A consensus on the rearrangement of nanostructures of C-S-H as a main consequence of creep, has almost been achieved. However, main disagreement still exists on two basic aspects regarding creep mechanisms: (1) at which site the creep occurs, like at interlayer, intergranular, or regions where C-S-H has a relatively higher solubility; (2) how the structural rearrangement evolutes, like in a manner of interlayer sliding, intra-transfer of water at various scales, recrystallization of gelled-like particles, or dissolution-diffusion-reprecipitation at inter-particle boundary. The further understanding of creep behavior of C-S-H relies heavily on the appropriate characterization of its nanostructure.

• Journal of Magnetics
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• 제10권2호
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• pp.44-47
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• 2005

The oscillatory interlayer exchange coupling (IEC) has been shown in pinned $[CoFe/Pt(t_{pt})/CoFe]/IrMn$ multi-layers with perpendicular anisotropy. The period of oscillation corresponds to about 2 monolayers of Pt. The oscillatory behavior of IEC depending on the nonmagnetic metallic Pt thickness is thought to be related the antiferromagnetic ordering induced by IrMn layer. Oscillatory IEC as function of insulating NiO thickness has been observed in $[Pt/CoFe]_4/NiO(t_{NiO})/[CoFe/Pt]_4$ multilayers. The effect of N (number of bilayer repeats) upon the magnetic property of [Pt/CoFe]N/IrMn is also studied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.353-356
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• 1999

The electrical characteristics of fatty acid LB films were investigated to develop the gas sensor using Langmuir-Blodgett(LB) films which have high ordered orientation and ordering structure. The deposition status of fatty acid LB films were verified by the measurements of UV absorbance. The conductivity of fatty acid LB films for horizontal direction at room temperature was about $10^8[S/cm]$,/TEX>, which was correspond to semiconductor material. The activation energy for fatty acid LB films with respect to variation of temperature was about l.O[eV]. The response characteristics for organic gas were confirmed by measuring the response time, recovery time, and reproducibility of the fatty acid LB films to each organic gas. Also, the penetration and adsorption behavior of gas molecule were confirmed through the organic gas response characteristics of fatty acid LB films with respect to temperature.

• 지능정보연구
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• 제1권1호
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• pp.61-72
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• 1995

Dynamic and explicit ordering of strategies is a key process in modeling knowledge-level problem-solving behavior. This paper addressed the important problem of howl to make the scheduler more knowledge-intensive in a way that facilitates the acquisition, integration, and maintenance of the scheduler control knowledge. The solution a, pp.oach described in this paper involved formulating the scheduler task as a heuristic classification problem, and then implementing it as a classification expert system. By doing this, the wide spectrum of known methods of acquiring, refining, and maintaining the knowledge of a classification expert system are a, pp.icable to the scheduler control knowledge. One important innovation of this research is that of recursive heuristic classification : this paper demonstrates that it is possible to formulate and solve a key subcomponent of heuristic classification as heuristic classification problem. Another key innovation is the creation of a method of dynamic heuristic classification : the classification alternatives that are selected among are dynamically generated in real-time and then evidence is gathered for and aginst these alternatives. In contrast, the normal model of heuristic classification is that of structured selection between a set of preenumerated fixed alternatives.

• International Journal of Reliability and Applications
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• 제2권2호
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• pp.81-97
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• 2001

Lifetesting problems have been the subject of investigations for over three decades. Most suggested approaches are markedly different from those used in the related but wider goodness of fit problems. In the current investigation, it is demonstrated that a goodness of fit approach is possible in many lifetesting problems and that It results in simpler procedures that are asymptotically equivalent or better than standard ones. They may also have superior finite sample behavior. Several perennial classes are addressed here. The class of increasing failure rate (IFR) and the class of new better than used (NBU) are addressed first. In addition, we provide testing for a newer and practical class of new better than used in convex ordering (NBUC) due to Cao and Wang (1991). Other classes can be developed similarly and this point is illustrated with the classes of new better than used in expectation (NBUE) and harmonic new better than used in expectation (HNBUE).

• 폴리머
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• 제27권6호
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• pp.521-527
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• 2003

신디오택틱 폴리프로필렌 (sPP)과 아이소택틱 폴리프로필렌 (iPP)은 용융과정에서 결정의 재배열이 나타나며 이와 같은 재결정 현상을 해석하기 위하여 결정화도와 결정구조의 변화, 동역학적 물성을 고찰하였고 DSC, FT-IR, SAXS, DMA를 이용하였다. 본 연구에서 실험된 조건에서는 sPP의 재결정화 현상을 확인할 수 없었으며, iPP는 용융으로부터 냉각되는 속도가 빠르게 될 수록 재가열시 재결정화 현상이 두드러졌다. iPP의 재결정화가 진행되는 동안 tan $\delta$가 0.119에서 0.101로 감소하여 탄성율이 증가한 결과를 보이나 결정화도는 거의 일정하게 유지되었다. 더욱이 재결정 현상이 진행되는 동안 SAXS 산란피크의 반가폭이 약 30% 감소하여 라멜라의 질서가 증가하는 거동을 보였다.

• 디지털융복합연구
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• 제20권4호
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• pp.159-168
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• 2022

본 연구는 외식동기요인을 기초로 하여 세분집단을 분류한 다음 인구통계학적 특성과 이용행태별, 이용동기가 외식점 선택행동과의 미치는 영향관계를 분석하고자 2021년 7월 15일부터 8월 14일 한달간 설문조사를 실시하였고 총 310부를 실증분석에 사용하였다. 연구결과 첫째, 외식동기에 따른 세분집단간 인구통계학적 특성에 따라서 미치는 영향관계에서 업무형은 남성이 여성보다 높게 나타났고, 군집수가 많은 변화형, 식도락형, 적합형은 여성이 높게 나타났다. 둘째, 인구통계적특성에서 모든 집단들이 공통적으로 31-40세, 41-50세의 기혼자들이 외식동기가 강한 것으로 나타났다. 셋째, 외식동기에 따른 세분집단간 이용행태적 차이에서 가장 선호하는 메뉴는 변화형을 제외한 업무형, 식도락형, 적합형은 한식이 가장 높았고, 변화형은 양식이 가장 높았다. 넷째, 세분집단간 이용행태적 차이의 주문방식에서 4개의 집단이 모두 무한리필이나 뷔페식보다는 주문식이 높게 나타났다. 본 연구의 한계점으로는 분야를 한정하여 분석이 이루어 져야 하지만 특정음식종목에 대하여 연구결과를 얻지 못하였다. 따라서 향후 연구에서는 특정 음식분야를 지정하여 구제적인 연구가 이루어지길 바란다.

• Progress in Superconductivity
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• 제14권2호
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• pp.110-115
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• 2012

Samples with nominal compositions of $RuSr_2(Eu_{1.34-x}Tb_xCe_{0.66})Cu_2O_z$ (x = 0, 0.67) were prepared and their superconductivity and magnetic properties were compared to shed light on the effect of Tb substitution for Eu. X-ray diffraction measurements indicate that the Tb substitution resulted in a decrease in both a and c lattice parameters in consistent with ionic size difference between Eu and Tb. Contrary to the Tb-free sample, no superconducting transition behavior is observed in the Tb-sustituted sample. It is also found that the Tb substitution for Eu significantly increases the weak-ferromagnetic component of the field-cooled magnetic susceptibility as well as an increase in the magnetic ordering temperature. These results suggest that the magnetic state of the Ru sublattice is significantly affected by the Tb substitution for Eu.

• Asia pacific journal of information systems
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• 제13권4호
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• pp.229-255
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• 2003

This article attempts to examine the well-known law that the increasing returns to scale(IRS) is effective in the Internet business. The effect of IRS is one of the hottest issues in the Internet business sector. Many cases and survey studies support the fact that the IRS phenomenon exists in the Internet business. Executives in Internet business generally give a deep trust on this theory. As the Internet business grows, however, the boundary of the business becomes widened and complicated. And each category of Internet business is characterized with a different business style and economic behavior. It may, therefore, be dangerous to accept that the phenomenon of IRS is applied to all areas of Internet business. For this reason, the research for the close look into the IRS phenomenon should provide significant implications for the managers in the Internet business industry. This article divides the internet business into four sub-areas, and analyzes the IRS phenomenon using AHP/DEA-based full ordering technique. Interpretations are given, based upon the research results, for each sub-area of Internet business, as a guideline of setting business strategies for practical managers.

• 한국컴퓨터산업학회논문지
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• 제2권11호
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• pp.1365-1372
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• 2001

이 연구는 사용자의 브라우징 행위에 따라 자동적으로 하이퍼텍스트 네트워크를 재구성하는 세 가지 학습 규칙을 제안하고, 실험적 시스템을 구현하였다. 시스템은 링크 가중치를 하이퍼링크 네트워크에 부여하고 학습 규칙에 따라 가중치를 변경한다. 학습 규칙은 하이퍼링크가 얼마나 자주 이용되고 있는지에 따라 해당 하이퍼링크의 가중치만 변경되며, 다른 하이퍼링크에는 영향을 미치지 않는다. 네트워크 구조의 변경은 링크 가중치의 내림차순에 따라 동적으로 링크가 배열되어 사용자에게 제시된다. 이것은 협력 필터링 기술의 장점과 탐색 지원 접근 방식을 혼합한 것이다. 실험을 위해 임의적인 하이퍼텍스트 네트워크를 만들고 사용자의 브라우징 선호에 따라 네트워크 구조가 변화되는 과정을 관찰한다.