• Coupled systems mechanics
• /
• 제7권2호
• /
• pp.211-232
• /
• 2018

In this work we present an upscaling technique for multi-scale computations based on a stochastic model calibration technique. We consider a coarse-scale continuum material model described in the framework of generalized standard materials. The model parameters are considered uncertain, and are determined in a Bayesian framework for the given fine scale data in a form of stored energy and dissipation potential. The proposed stochastic upscaling approach is independent w.r.t. the choice of models on coarse and fine scales. Simple numerical examples are shown to demonstrate the ability of the proposed approach to calibrate coarse scale elastic and inelastic material parameters.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.158-159
• /
• 2006

The resistance-capacitance (RC) delay of signals through interconnection materials becomes a big hurdle for high speed operation of semiconductors which contain multilayer interconnection layers. In order to reduce the RC delay, low-k materials will be used for inter-metal dielectric (IMD) materials. We have developed self-consistent simulation tool that includes neutral-species transport model, based on the relaxation continuum (RCT) model. We present the parametric study of the modeling results of a two-frequency capacitively coupled plasma (2f-CCP) with $N_2/H_2$ gas mixture that is known as promising one for organic low-k materials etching. We include the neutral transport model as well as plasma one in the calculation. The plasma and neutrals are calculated self-consistently by iterating the simulation of both species till a spatiotemporal steady state profile could be obtained.

• Korean Linguistics
• /
• 제79권
• /
• pp.63-89
• /
• 2018

This study explores contrastive relation among voiced bilabial fricative [${\ss}$], voiceless bilabial stop [p] and glide [w] in Middle Korean consonant system based on Probabilistic Model. Preceding researches about voiced bilabial fricative [${\ss}$] proposed two influential arguments. One is voiced bilabial fricative [${\ss}$] was an independent phoneme, the other is it was not an independent phoneme but an allophone of voiceless bilabial stop [p] in Middle Korean. This study applies Probabilistic Phonological Relationship Model (PPRM) for solving the problem of dichotomy about contrastive and allophonic relations. The analysis result of the contrastive entropy by PPRM suggests that voiced bilabial fricative [${\ss}$] was just an allophone of voiceless bilabial stop [p] or glide [w] in Middle Korean. Comparing the entropies between [p] and other consonants with the entropies between [${\ss}$] and other consonants, a continuum defined in terms of entropy reveals that [${\ss}$] in Middle Korean was more allophonic than phonemic.

• Nuclear Engineering and Technology
• /
• 제54권5호
• /
• pp.1541-1548
• /
• 2022

The thermal conductivity of uranium oxide (UO₂) containing pores and grain boundaries is investigated using continuum-level simulations based on the finite-difference method in two and three dimensions. Steady-state heat conduction is solved on microstructures generated from the phase-field model of the porous polycrystal to calculate the effective thermal conductivity of the domain. The effects of porosity, pore size, and grain size on the effective thermal conductivity of UO₂ are quantified. Using simulation results, a new empirical model is developed to predict the effective thermal conductivity of porous polycrystalline UO₂ fuel as a function of porosity and grain size.

• Steel and Composite Structures
• /
• 제23권2호
• /
• pp.229-238
• /
• 2017

This paper presents a combined numerical and theoretical study on the composite action between steel and concrete of circular steel tube confined concrete (STCC) stub columns under axial compressive loading with a full theoretical elasto-plastic model and finite element (FE) model in comparison with experimental results. Based on continuum mechanics, the elasto-plastic model for STCC stub columns was established and the analysis was realized by a FORTRAN program and the three dimensional FE model was developed using ABAQUS. The steel ratio of the circular STCC columns were defined in range of 0.5% to 2% to analyze the composite action between steel tube and concrete, and make a further study on the advantages of the circular STCC columns. By comparing the results using the elasto-plastic methods with the parametric analysis result of FE model, the appropriate friction coefficient between the steel tube and core concrete was defined as 0.4 to 0.6. Based on ultimate balance theory, the formula of ultimate load capacity applying to the circular STCC stub columns was developed.

• Journal of the Korean Society for information Management
• /
• 제21권2호
• /
• pp.153-167
• /
• 2004

The purpose of this study is to discuss ′records′ as core resources for knowledge management and to suggests the directions for developing integrated knowledge management systems based records management. This present paper begins with analyzing concept and structure of records in light of knowledge management, and identify the importance of records management in developing knowledge management systems by substituting evidence axis in Upward′s "Records Continuum Model" for knowledge management. And this study tries to identify critical aspects regarding transfer of records to knowledge system by analyzing the level of records. Based on these analyses, it suggests a directions for developing records based-knowledge management systems.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• 제28권3호
• /
• pp.309-316
• /
• 2015

A state-based peridynamic model is able to describe a general constitutive model from the standard continuum theory. The response of a material at a point is dependent on the deformation of all bonds connected to the point within the nonlocal horizon region. Therefore, the state-based peridynamic model permits both the volume and shear changes of the material which is promising to reproduce the complicated dynamic brittle fracture phenomena, such as crack branching, secondary cracks, cascade cracks, crack coalescence, etc. In this paper, the two-dimensional state-based peridynamic model for a linear elastic plane stress solid is employed. The damage model incorporates the energy release rate and the peridynamic energy potential. For brittle glass materials, the impact of the crack-parallel compressive stress waves on the crack branching pattern is investigated. The peridynamic solution for this problem captures the main features, observed experimentally, of dynamic crack propagation and branching. Cascade cracks under strong tensile loading and secondary cracks are also well reproduced with the state-based peridynamic simulations.

• Journal of the Korean Association of Geographic Information Studies
• /
• 제15권1호
• /
• pp.99-118
• /
• 2012

The aim of this study is to define a correlation between spatial distribution characteristics of FFG(Functional Feeding Groups) of aquatic insects and related environmental factors in the Geum River based on the theory of RCC(River Continuum Concept). For that objective we had used SMRA(Stepwise Multiple Regression Analysis) method to analyze close relationship between the distribution of aquatic insects and the physical and chemical factors that may affect their inhabiting environment in the study area. And then, a probabilistic method named Frequency Ratio Model(FRM) and spatial analysis function of GIS were applied to produce a predictive distribution map of biota community considering their distribution characteristics according to the environmental factors as related variables. As a result of SMRA, the values of decision coefficient for factors of elevation, stream width, flow velocity, conductivity, temperature and percentage of sand showed higher than 0.5. Therefore these 6 environmental factors were considered as major factors that might affect the distribution characteristics of aquatic insects. Finally, we had calculated RMSE(Root Mean Square Error) between the predicted distribution map and prior survey database from other researches to verify the result of this study. The values of RMSE were calculated from 0.1892 to 0.4242 according to each FFG so we could find out a high reliability of this study. The results of this study might be used to develop a new estimation method for aquatic ecosystem with macro invertebrate community and also be used as preliminary data for conservation and restoration of stream habitats.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 한국소성가공학회 2006년도 춘계학술대회 논문집
• /
• pp.199-202
• /
• 2006

The hardening and anisotropy based on the crystal plasticity is considered in the numerical simulation of hemispherical sheet forming process to find more realistic simulation results For calculating the yield shear stresses of each crystal, Taylor's model of the crystalline aggregate is employed. The yield stress of crystalline aggregate is computed by averaging the yield stresses of the crystal. The hardening is evaluated by using the Taylor factor and the critical resolved shear stress of the crystal. In addition, by observing the crystallographic texture and slip system, the anisotropy of the sheet is traced during the forming process. The anisotropy and hardening behaviors of the sheet found by the crystal plasticity are described better than those of obtained from the Hill's quadratic criterion based on the continuum plasticity.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권2호
• /
• pp.209-218
• /
• 2017

Sea ice is the main factor affecting the safety of the Arctic engineering. However, traditional numerical methods derived from classical continuum mechanics have difficulties in resolving discontinuous problems like ice damage. In this paper, a non-local, meshfree numerical method called "peridynamics", which is based on integral form, was applied to simulate the interaction between level ice and a cylindrical, vertical, rigid structure at different velocities. Ice in the simulation was freshwater ice and simplified as elastic-brittle material with a linear elastic constitutive model and critical equivalent strain criterion for material failure in state-based peridynamics. The ice forces obtained from peridynamic simulation are in the same order as experimental data. Numerical visualization shows advantages of applying peridynamics on ice damage. To study the repetitive nature of ice force, damage zone lengths of crushing failure were computed and conclude that damage zone lengths are 0.15-0.2 times as ice thickness.