• Interaction and multiscale mechanics
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• 제2권4호
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• pp.353-374
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• 2009

A new seamless multiscale simulation was developed for coupling the continuum model with its molecular dynamics. Kriging-based Finite Element Method (K-FEM) is employed to model the continuum base of the entire domain, while the molecular dynamics (MD) is confined in a localized domain of interest. In the coupling zone, where the MD domain overlaps the continuum model, the overall Hamiltonian is postulated by contributions from the continuum and the molecular overlays, based on a quartic spline scaling parameter. The displacement compatibility in this coupling zone is then enforced by the Lagrange multiplier technique. A multiple-time-step velocity Verlet algorithm is adopted for its time integration. The validation of the present method is reported through numerical tests of one dimensional atomic lattice. The results reveal that at the continuum/MD interface, the commonly reported spurious waves in the literature are effectively eliminated in this study. In addition, the smoothness of the transition from MD to the continuum can be significantly improved by either increasing the size of the coupling zone or expanding the nodal domain of influence associated with K-FEM.

• 한국철도학회논문집
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• 제3권2호
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• pp.43-50
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• 2000

The corrugated panels are the prime candidate structure for the floor, roof and wall of Korean high speed train. The equivalent continuum modeling approach panels can be used for the efficient design and evaluation of their structural characteristics. The equivalent continuum models, derived from the true complex corrugated panels, should have the same structural behavior as the original structures have. This paper briefly reviews three representative continuum modeling methods: the static analysis method and two plate-models based on modal analysis methods (MAM). These methods are evaluated through some numerical examples by comparing the natural frequencies and static deflections. It is observed that the plate-model based on Rayleigh-Ritz method seems to provide the best results when used in conjunction with the cantilever-type boundary conditions. The equivalent elastic constants of various corrugated panels, depending on the changes in their configurations, are tabulated for efficient use in structural design.

• 대한기계학회논문집
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• 제17권11호
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• pp.2704-2710
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• 1993

A simple and straightforward method is introduced for developing continuum beam-rod model of a box-beam typed aircraft wing with composite layered skin based on "energy equivalence." The equivalent continuum structral properties are obtained from the direct comparison of the reduced stiffness and mass matrices for box-beam typed wing with those for continuum beam-rod model. The stiffness and mass matrices are all represented in terms of the continuum degrees-of freedom defined in this paper. The finite-element method. The advantage of the present continuum method is to give every continuum structural properties including all possible coupling terms which represent the couplings between different deformations. To evaluate the continuum method developed in this paper, free vibration analyses for both continuum beam-rod and box-beam are conducted. Numerical tests show that the present continuum method gives very reliable structural and dynamic properties compared to the results by the conventional finite-element analysis. analysis.

• 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.

• 한국도서관정보학회지
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• 제53권3호
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• pp.25-46
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• 2022

본고에서는 레코드 컨티뉴엄에서의 평가 논리를 분석하였다. 전자기록 환경에서의 평가가 지닌 보다 근원적인 함의를 파악하기 위해서는 레코드 컨티뉴엄에 내재되어 있는 평가 논리에 대한 분석이 필수적으로 요구된다. 레코드 컨티뉴엄은 기존의 라이프사이클을 기반으로 한 평가 논리 및 여기서 연유한 양분화된 기록관리체제에 대한 반론에서 출발한 이론체계라는 점에서, 전자기록 환경에서의 평가에 관한 이론적 기반을 제공해 줄 수 있다. 특히 평가는 기록이 지닌 의미를 모색하는 합목적적 행위임을 감안할 때, 레코드 컨티뉴엄에서 의도한 기록의 개념 및 의미에 대한 재해석은 이전과는 다른 평가상의 논리들을 도출할 수 있게 해준다. 이에 본고에서는 라이프사이클 평가 논리와의 비교 및 레코드 컨티뉴엄에서 제시한 새로운 기록에 대한 인식을 기반으로, 레코드 컨티뉴엄 평가 논리상의 핵심 요소를 세 가지 측면에 초점을 맞추어 분석하였다.

• Journal of Theoretical and Applied Mechanics
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• 제1권1호
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• pp.97-109
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• 1995

In this paper, a finite viscoelastic continuum model for rubber and its finite element analysis are presented. This finite viscoelatic model based on continuum mechanics is an extended model of Johnson and Wuigley's 1-D model. In this extended model, continuum based kinematic measures are rigorously defied and by using this kinematic measures, elastic stage law and flow rule are introduced. In kinematics, three configuration are introduced. In kinematics, three configuration are introduced. They are reference, current and virtual visco configurations. In elastic state law, it is assumed that at a certain time, there exists an elastic potential which describes the recoverable elastic energy. From this elastic potential, elastic state law is derived. The proposed flow rule is based on phenomenological observation. The flow rule gives precise relaxation response. In finite element approximation, mixed Lagrangian description is used, where total and similar method of updated Lagrangian descriptions are used together. This approach reduces the numerical job and gives simple nonlinear syatem of equations. To satisfy the incompressible condition, penalty-type modified Mooney-Rivlin energy function is adopted. By this method nearly incompressible condition is obtain the virtual visco configuration. For verification, uniaxial stretch tests are simulated for various stretch rates. The simulated results show good agreement with experiments. As a practical experiments. As a preactical example, pressurized rubber plate is simulated. The result shows finite viscoelastic effects clearly.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.197-204
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• 2002

In this study, multivariate analysis based on domestic data(958 EA) of road tunnel, and suggest the easy prediction equation of Q-system. We generate applicable Q-value to numerical analysis method with using the equation and investigate the behavior as variable Q-value of rock mass induced excavation with discontinuum numerical analysis method, UDEC. In the result of the experiment, we research the application range of Q-value to apply the continuum model to discontinuous rock mass is below 0.7 and we testify the applicability of continuum model as researched Q-value with continuum numerical analysis method, FLAC.

• 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.

• Structural Engineering and Mechanics
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• 제67권1호
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• pp.79-85
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• 2018

Topology optimization of steel and concrete composite based on truss-like material model is studied in this paper. First, the initial design domain is filled with concrete, and the steel is distributed in it. The problem of topology optimization is to minimize the volume of steel material and solved by full stress method. Then the optimized steel and concrete composite truss-like continuum is obtained. Finally, the distribution of steel material is determined based on the optimized truss-like continuum. Several numerical results indicate the numerical instability and rough boundary are settled. And more details of manufacture and construction can be presented based on the truss-like material model. Hence, the truss-like material model of steel and concrete is efficient to establish the distribution of steel material in concrete.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.279-301
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• 2008

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.