• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.527-531
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• 2007

The classical continuum theory-based thin film model is independent of their size and the surface effect can be ignored. But the surface to bulk ratio becomes very large in nano-size structures such as nano film, nano wire and nano beam. In this case, surface effect plays an important role and its contribution of the surface effect must be considered. Molecular dynamics simulation has been a conventional way to analyze these ultra-thin structures but structures in the range between submicro and micro are difficult to analyze by classical molecular dynamics due to the restriction of computing resources and time. Therefore, in present study, the continuum-based method is considered to predict the overall physical and mechanical properties of the structures in nano-scale, especially, for the thin-film. The proposed continuum based-thin plate finite element is efficient and reliable for the prediction of nano-scale film behavior.

• 한국기록관리학회지
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• 제22권3호
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• pp.21-36
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• 2022

최근 기록이 지닌 정보로서의 속성에 주목해야 한다는 논의가 활발히 제기되고 있다. 이는 전자기록 환경을 맞아 행위에 대한 증거로서의 속성에만 초점을 맞추어 온 동향에 대한 반향이다. 하지만 아직까지 기록이 지닌 정보로서의 속성에 대한 명확한 개념은 정립되지 않은 상태이다. 이에 본고에서는 기록과 정보 간의 관계 정립을 위한 일환으로 정보 컨티뉴엄 모델을 분석하고자 한다. 정보 컨티뉴엄은 레코드 컨티뉴엄을 기반으로 레코드키핑 관점에서의 새로운 정보 개념을 정립하기 위해 고안된 이론 체계로, 레코드키핑 내에 존재하는 정보관리를 위한 요소들을 파악할 수 있는 하나의 개념적 틀을 제공해준다. 이에 2장에서는 레코드 컨티뉴엄 개발 이후 정보 컨티뉴엄이 개발된 배경 및 과정을 살펴본 다음, 구조주의 이론 등 정보학 이론을 차용해 정립한 정보의 개념을 레코드 컨티뉴엄과 연계하여 고찰하였다. 이어 3장에서는 정보 컨티뉴엄의 개념적 구조와 함께 정보의 활용 목적 및 방식을 고찰한 후, 레코드키핑 내에 존재하는 정보관리를 위한 요소들을 구조적으로 도식화한 정보 컨티뉴엄 모델상의 4개 차원 및 속성을 분석하였다. 이러한 분석을 기반으로 4장에서는 정보 컨티뉴엄이 지닌 의의 및 한계를 제시하고자 하였다.

• Interaction and multiscale mechanics
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• 제1권4호
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• pp.467-476
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• 2008

In this work, a nano-size rocksalt crystal (magnesium oxide) is considered as a continuous collection of unit cells, while each unit cell consists of discrete atoms; and modeled by a multiscale concurrent atomic/continuum field theory. The response of the crystal to an electromagnetic (EM) wave is studied. Finite element analysis is performed by solving the governing equations of the multiscale theory. Due to the applied EM field, the inhomogeneous motions of discrete atoms in the polarizable crystal give rise to the change of microstructure and the polarization wave. The relation between the natural frequency of this system and the driving frequency of the applied EM field is found and discussed.

• Korea-Australia Rheology Journal
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• 제21권4호
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• pp.245-268
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• 2009

Recent developments in dilute polymer solution rheology are reviewed, and placed within the context of the general goals of predicting the complex flow of complex fluids. In particular, the interplay between the use of polymer kinetic theory and continuum mechanics to advance the microscopic and the macroscopic description, respectively, of dilute polymer solution rheology is delineated. The insight that can be gained into the origins of the high Weissenberg number problem through an analysis of the configurational changes undergone by a single molecule at various locations in the flow domain is discussed in the context of flow around a cylinder confined between flat plates. The significant role played by hydrodynamic interactions as the source of much of the richness of the observed rheological behaviour of dilute polymer solutions is highlighted, and the methods by which this phenomenon can be incorporated into a macroscopic description through the use of closure approximations and multi scale simulations is discussed.

• Steel and Composite Structures
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• 제17권5호
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• pp.641-665
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• 2014

This paper presents the analytical solutions for the size-dependent static analysis of the functionally graded (FG) beams with various boundary conditions based on the nonlocal continuum model. The nonlocal behavior is described by the differential constitutive model of Eringen, which enables to this model to become effective in the analysis and design of nanostructures. The elastic modulus of beam is assumed to vary through the thickness or longitudinal directions according to the power law. The governing equations are derived by using the nonlocal continuum theory incorporated with Euler-Bernoulli beam theory. The explicit solutions are derived for the static behavior of the transversely or axially FG beams with various boundary conditions. The verification of the model is obtained by comparing the current results with previously published works and a good agreement is observed. Numerical results are presented to show the significance of the nonlocal effect, the material distribution profile, the boundary conditions, and the length of beams on the bending behavior of nonlocal FG beams.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.445-455
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• 2019

Since the days of yore, plate's flexural analysis and formulation were dependent on the assumed coordinate system. In uncovering the coordinates-independent flexural interpretation, in this study, the plate bending analysis has been interpreted in terms of the tensor's components of curvatures and bending moments, in accordance with the continuum mechanics. The paper herein presents the theoretical formulations and conceptual perspectives of the Hydrostatic Method of Analysis (HM) that combines the continuum mechanics with the elasticity theory; the graphical statics and analysis; the theory of thin isotropic and orthotropic plates.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.431-448
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• 2012

In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

• 한국수학사학회지
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• 제33권6호
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• pp.327-343
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• 2020

This study investigate philosophical discussions related to the Zeno's paradoxes in order to derive the mathematics educational implications. The paradox of Zeno's motion is sometimes explained by the calculus theories. However, various philosophical discussions show that the resolution of Zeno's paradox by calculus is not a real solution, and the concept of a continuum which is composed of points and the real number continuum may not coincide with the physical space and time. This is supported by the fact that the hyperreal number system of nonstandard analysis could be another model of a straight line or time and that an alternative explanation of Zeno's paradox was possible by the hyperreal number system. The existence of two different theories of the continuum suggests that teachers and students may not have the same view of the continuum. It is also suggested that the real world model used in school mathematics may not necessarily match the student's intuition or mathematical practice, and that the real world application of mathematics theory should be emphasized in education as a kind of 'correspondence.'

• Advances in nano research
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• 제14권6호
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• pp.521-525
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• 2023

This paper concerned with the vibration of double walled carbon nanotubes (CNTs) as continuum model based on Timoshenko-beam theory. The vibration solution obtained from Timoshenko-beam theory provides a better presentation of vibration structure of carbon nanotubes. The natural frequencies of double-walled CNTs against half axial wave mode are investigated. The frequency decreases on decreasing the half axial wave mode. The shape of frequency arcs is different for various lengths. It is observed that model has produced lowest results for C-F and highest for C-C. A large parametric study is performed to see the effect of half axial wave mode on frequencies of CNTs. This numerically vibration solution delivers a benchmark results for other techniques. The comparison of present model is exhibited with previous studies and good agreement is found.

• 한국기록관리학회지
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• 제21권3호
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• pp.1-16
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• 2021

레코드 컨티뉴엄은 전자기록 환경으로 이행하는 패러다임 전환기에 기록학의 기반을 제공하는 이론임에도 불구하고, 이에 대한 비판적 분석을 그동안 거의 수행되지 않았다. 레코드 컨티뉴엄은 아직 개발이 진행 중인 이론으로, 핵심은 라이프사이클 모델과는 다른 기록에 대한 새로운 시각이다. 따라서 전자기록 환경에서 레코드 컨티뉴엄이 지닌 의미 및 한계를 분석하고 보다 심도 있는 이론적 개발을 위해서는 레코드 컨티뉴엄 논리 속에 함유된 기록의 의미 및 속성에 대한 분석이 필수적으로 요구된다. 하지만 레코드 컨티뉴엄에서는 기록에 대해 별도로 정의를 내리지 않고 있다. 이에 본고에서는 최근의 전자기록 환경에서 레코드 컨티뉴엄 이론 속에 함유된 기록의 의미 및 속성을 축선 및 차원 분석을 통해 고찰하고자 하였다. 이를 위해 우선 기록의 의미 및 속성 도출을 위한 기초 작업으로, 컨티뉴엄 모델상의 차원 1 및 차원 2에 초점을 맞추어 분석을 수행하였다. 이어 컨티뉴엄 논리 속에 함유된 기록의 의미 및 속성을 라이프사이클 모델과 결부시켜 고찰하였으며, 이를 기반으로 컨티뉴엄이 지닌 의의를 고찰한 다음, 기록의 의미 및 속성 관점에서 컨티뉴엄이 지닌 한계를 제시하였다.