• Structural Engineering and Mechanics
• /
• v.5 no.3
• /
• pp.221-237
• /
• 1997

This paper presents a new uniaxial material model for rate-sensitive analysis addressing both the transient and steady-state responses. The new model adopts visco-plastic theory for the rate-sensitive response, and employs a three-parameter representation of the overstress as a function of the strain-rate. The third parameter is introduced in the new model to control its transient response characteristics, and to provide flexibility in fitting test data on the variation of overstress with strain-rate. Since the governing visco-plastic differential equation cannot be integrated analytically due to its inherent nonlinearity, a new single-step numerical integration procedure is proposed, which leads to high levels of accuracy almost independent of the size of the integration time-step. The new model is implemented within the nonlinear analysis program ADAPTIC, which is used to provide several verification examples and comparison with other experimental and numerical results. The companion paper extends the three-parameter model to trilinear static stress-strain relationships for steel and concrete, and presents application examples of the proposed models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.154-157
• /
• 2004

With the need of high-speed and mass data transmission, optical communication system requires the growth of optical components. Waveguide photodiodes(WGPDs) are introduced and circuit models of WGPD and submodule are required for the optical receiver application. In this paper, the circuit models of WGPD and submodule are investigated and modeling results are derived by PEEC methodology. The s-parameters are measured for the test structures of WGPD and submodule and the equivalent circuit models are examined. The modeling results agreed well with the measured data and can present a reasonable physical representation.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.45 no.3
• /
• pp.41-53
• /
• 2017

This study was performed to determine what the plant material were selected to reflect in the 2016 Korea Garden Show designer's garden. It was analyzed that plant material was used to display the theme of the garden and to create a specific space. Under the given theme of 'K-Garden, Shinhallyu Garden(new style garden culture) with the most Korean taste', the plants were used to highlight the theme in two types: 'representation' and 'expression'. There were two 'representation' gardens that imitate a particular space of Korean taste and four 'expression' gardens that showcase the designer's thoughts with abstract concepts and concrete objects. Three gardens included both types of garden. The way of revealing the subject with plants was used more for 'expression' than for 'representation'. There were eleven spaces for 'representation' of the Korean taste, a vegetable garden, faucet, pond, field, nature, a Hanok court garden, groves of bamboo, tile roof, stone wall, rock and backyard of a Hanok connected to the mountain. The planting material was used in two ways: reflecting only the ecological characteristics of the plant, and considering the ecological and visual characteristics together. Vegetation plantings reflecting the ecological characteristics were observed in all eleven spaces. Nine of the spaces reflected the growth environment of the plants, but the other two did not reflect the ecological characteristics of the plants, unlike the designer's intention. In the case of the four spaces that considered the ecological and visual characteristics together, color and size were considered visual characteristics. The plants in the seven spaces that included 'expression' as the theme were selected to reflect the visual characteristics in the order of color, shape, texture, and size, rather than reflecting ecological characteristics. A group planting method was applied. When the plants were used as materials for creating space, Norman(1989) analyzed three enclosure factors(overhead, vertical, ground plane). Only two deciduous trees were used in the overhead plane while five species of evergreen shrubs and thirty species of various deciduous plants were used in the vertical plane. There were forty-five species (nine trees and thirty-six herbaceous plants) forming the ground plane, and various herbaceous plants were utilized without duplication in each garden. The designer's garden of the Garden Show played a role in introducing new groundcover plants to the public. Three of the nine gardens did not include ornamental plants, and the use of decorative plants in other gardens was few compared to the number of plantings. In the Korea Garden Show designer's garden, most of the plants were being used with the intention of exposing the theme or architectural uses. In the 2016 Korea Garden Show designer's garden, many species of plants were used as materials for showcasing themes rather than for creating spaces. Also, the method of 'expression' was used more than the method of 'representation' in order to highlight the theme. This indicates that the planting materials reflect visual characteristics such as color, shape, texture, size rather than ecological characteristics.

• Journal of Korean Elementary Science Education
• /
• v.36 no.3
• /
• pp.256-272
• /
• 2017

The purpose of this research is to study and learn more features how this type of distribution for communication in $6^{th}$ grade first semester elementary science and mathematics according to communicative expression by 2009 revised curriculum. For this study, based on an analysis standard presented in previous research on the types of communication. The results of this research are as follows. First, because the mathematics presents the number of ways to communicate twice more than science, mathematics go through with much more problems to solve than science. Second, in mathematics, spoken method and written method have similar proportion, less in physical activity method. Third, Science showed balanced proportion among four areas; earth, life, energy, and material. On the other hand, mathematics only showed small numbers in the area of geometry but similar numbers in number and operations, regularity, measurement. Fourth, there is no common feature or relevance about communicative approach for convergence thinking in 2009 revised curriculum, it seems that it doesn't consider it as a revised.

• Structural Engineering and Mechanics
• /
• v.43 no.6
• /
• pp.739-759
• /
• 2012

The tailoring optimization technique recently developed by the author for improving structural response and energy absorption of composites is extended to sandwich shells using a previously developed zig-zag shell model with hierarchic representation of displacements. The in-plane variation of the stiffness properties of plies and the through-the thickness variation of the core properties are determined solving the Euler-Lagrange equations of an extremal problem in which the strain energy due to out-of-plane strains and stresses is minimised, while that due to their in-plane counterparts is maximised. In this way, the energy stored by unwanted out-of-plane modes involving weak properties is transferred to acceptable in-plane modes. As shown by the numerical applications, the critical interlaminar stress concentrations at the interfaces with the core are consistently reduced without any bending stiffness loss and the strength to debonding of faces from the core is improved. The structural model was recently developed by the author to accurately describe strain energy and interlaminar stresses from the constitutive equations. It a priori fulfills the displacement and stress contact conditions at the interfaces, considers a second order expansion of Lame's coefficients and a hierarchic representation that adapts to the variation of solutions. Its functional d.o.f. are the traditional mid-plane displacements and the shear rotations, so refinement implies no increase of the number of functional d.o.f. Sandwich shells are represented as multilayered shells made of layers with different thickness and material properties, the core being treated as a thick intermediate layer.

• Geomechanics and Engineering
• /
• v.14 no.5
• /
• pp.479-489
• /
• 2018

In this paper, a comparative study of the effects of soil modelling on the interaction between tunnelling in soft soil and adjacent piled structure is presented. Several three-dimensional finite element analyses are performed to study the deformation of pile caps and piles as well as tunnel internal forces during the construction of an underground tunnel. The soil is modelled by two material models: the simple, yet approximate Mohr Coulomb (MC) yield criterion; and the complex, but reasonable hardening soil (HS) model with hyperbolic relation between stress and strain. For the former model, two different values of the soil stiffness modulus ($E_{50}$ or $E_{ur}$) as well as two profiles of stiffness variation with depth (constant and linearly increasing) were used in attempts to improve its prediction. As these four attempts did not succeed, a hybrid representation in which the hardening soil is used for soil located at the highly-strained zones while the Mohr Coulomb model is utilized elsewhere was investigated. This hybrid representation, which is a compromise between rigorous and simple solutions yielded results that compare well with those of the hardening soil model. The compared results include pile cap movements, pile deformation, and tunnel internal forces. Problem symmetry is utilized and, therefore, one symmetric half of the soil medium, the tunnel boring machine, the face pressure, the final tunnel lining, the pile caps, and the piles are modelled in several construction phases.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.31 no.7
• /
• pp.1052-1063
• /
• 2007

This study focuses on the analysis of body images appearing in the fashion illustrations since the 1990's and thereby attempts to determine relationship between their expressional features and aesthetic values in reference to theory of post-structuralism. Especially among numerous post-structuralist, Michel Foucault, Gilles Deleuze/Felix Guattari, and Julia Kristeva set unique arguments on body, which provide valuable leads to decipher the image of body. For that reason, body images shown in the fashion illustration are categorized into grotesque body, fragmented body, humanoid body, and post-gendered body, and reviewed their characteristics and aesthetic values based on critics of above three scholars. Findings are summarized as follows: First, image of body entails meaning of an resistance of traditional social concepts and order, and second it serves the purpose of creating a new and unique sense. Finally, it is not an object of representation of physical facts, but rather a representation of the real itself, apart from presenting the original material. Given arguments enhance understanding of images of body in fashion illustration in a broader sense.

• Coupled systems mechanics
• /
• v.8 no.4
• /
• pp.299-313
• /
• 2019

The paper represents computer modeling of the deformed state of physically nonlinear transversally isotropic bodies with hole. In order to describe the anisotropy of the mechanical properties of transversally-isotropic materials a structurally phenomenological model has been used. This model allows representing the initial material in the form of the coupled isotropic materials: the basic material (binder) considered from the positions of continuum mechanics and the fiber material oriented along the anisotropy direction of the original material. It is assumed that the fibers perceive only the axial tensile-compression forces and are deformed together with the base material. To solve the problems of the theory of plasticity, simplified theories of small elastoplastic deformation have been used for a transversely-isotropic body, developed by B.E. Pobedrya. A simplified theory allows applying the theory of small elastoplastic deformations to solve specific applied problems, since in this case the fibrous medium is replaced by an equivalent transversely isotropic medium with effective mechanical parameters. The essence of simplification is that with simple stretching of composite in direction of the transversal isotropy axis and in direction perpendicular to it, plastic deformations do not arise. As a result, the intensity of stresses and deformations both along the principal axis of the transversal isotropy and along the perpendicular plane of isotropy is determined separately. The representation of the fibrous composite in the form of a homogeneous anisotropic material with effective mechanical parameters allows for a sufficiently accurate calculation of stresses and strains. The calculation is carried out under different loading conditions, keeping in mind that both sizes characterizing the fibrous material fiber thickness and the gap between the fibers-are several orders smaller than the radius of the hole. Based on the simplified theory and the finite element method, a computer model of nonlinear deformation of fibrous composites is constructed. For carrying out computational experiments, a specialized software package was developed. The effect of hole configuration on the distribution of deformation and stress fields in the vicinity of concentrators was investigated.

• Korean Journal of Cognitive Science
• /
• v.2 no.2
• /
• pp.205-220
• /
• 1990

Material substance may exist in two different modes of reality:real as physcal objects that comprise material cause and formal cause, and real as function networks that comprise efficient cause and functional cause.Functional networks are real as a mode of material substance because their efficient cause is energy consuming.Neural functional network, in this sense, are different from neural networks.In the same way, mental functional networks are real, for they are energy consuming and they function as a network.Mental functional networks, in turn, may divide into non-lingustic functional networks and linguistic functional networks.And further distinctions among the different levels of mental functional networks will be specified, and hence their reality confirmed more specifically as the research in cognitive science advances.

• Earthquakes and Structures
• /
• v.4 no.2
• /
• pp.203-217
• /
• 2013

In recent decades, it has been realized that increasing the lateral stiffness of structure subjected to lateral loads is not the only parameter enhancing safety or reducing damage. Factors such as ductility and damping govern the structural response due to lateral loads. Despite the significant contribution of damping in resisting lateral loads, especially at resonance, there is no accurate mathematical representation for it. The main objective of this study is to develop a damping identification procedure for linear systems based on a mixed numerical-experimental approach, assuming viscous damping. The proposed procedure has been applied to a laboratory experiment associated with a numerical model, where a hollow rectangular steel cantilever column, having three lumped masses, has been fixed on a shaking table subjected to different exciting waves. The modal damping ratio has been identified; in addition, the effect of adding filling material to the hollow specimen has been studied in relation to damping enhancement. The results have revealed that the numerically computed response based on the identified damping is in a good fitting with the measured response. Moreover, the filling material has a significant effect in increasing the modal damping.