• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.623-624
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• 2008

We present a level set method for numerical shape optimization of electromagnetic systems. The level set method does not only lead to efficient computational schemes, but also is able to handle topological changes such as merging, splitting and even disappearing of connected components. The velocity field on boundaries is obtained by a shape derivative of continuum sensitivity analysis using the material derivative concept and an adjoint variable technique. Two numerical results of dielectric optimization between electrodes showed that the level set method is feasible and effective in solving shape optimization problems of electromagnetic systems.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3201-3211
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• 2010

Previous work on the phase-shifted version of the multichannel quantum-defect theory (MQDT) for a system involving 2 closed and many open channels (Lee, C.-W. Bull. Korean Chem. Soc. 2010, 31, 1669) was extended to obtain the formulae of the spectral shape parameters with the structure of a pole extracted explicitly for general cases only limited by 2 non-degenerate closed channels. The theory was applied to the narrow $6p_{1/2,3/2}np$ J = 1 autoionizing Rydberg series in barium perturbed by the $6p_{3/2}nf$ states obtained by de Graaff et al.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.45-52
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• 2001

A series of unreinforced masonry (URM) walls were analytically investigated for a limited version of seismic in-plane performance. For this URM walls were assumed to be an elastic continuum and modeled as isotropic plane stress elements within which the nature of cracking was propagated. Accordingly, cracking mode of behavior in URM was modeled by smeared-crack approach. Total of 70 cases were considered for various parameters such as axial load ratio, aspect ratio and effective section area ratio due to the existence of opening, etc. The analysis results indicated a general tendency in base shear coefficient and deformability of URM walls for these variables.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.171-178
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• 1997

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for the multispan partially prestressed concrete beams. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non-prestressing steel and formwork is minimized. The design constraints include limits on the maximum deflection, flexural and shear strengths, in addition to ductility requirements, and upper and lower bounds on design variables as stipulated by the design code. Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables-effective depth, eccentricity of prestressing steel and non-prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. The self-weight of the structure is included in the equilibrium equation of the real system, as is the secondary effect resulting from the prestressing force. Two numerical examples of multispan PPC beams with rectangular cross-section are solved to show the applicability and efficiency fo the DCOC-based technique.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1499-1506
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• 2001

Various transition elements are used in general for the effective finite element analysis of complicated mechanical structures. In this paper, a solid-to-beam transition finite element, which can b e used for connecting a C1-continuity beam element to a continuum solid element, is proposed. The shape functions of the transition finite element are derived to meet the compatibility condition, and a transition element equation is formulated by the conventional finite element procedure. In order to show the effectiveness and convergence characteristics of the proposed transition element, numerical tests are performed for various examples. As a result of this study, following conclusions are obtained. (1) The proposed transition element, which meets the compatibility of the primary variables, exhibits excellent accuracy. (2) In case of using the proposed transition element, the number of nodes in the finite element model may be considerably reduced and the model construction becomes more convenient. (3) This formulation method can be applied to the usage of higher order elements.

• 한국안전학회지
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• 제10권3호
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• pp.3-10
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• 1995

For most engineering materials are influenced by the dominant mechanism resisting crack extention under large scale yielding conditions. Continuum mechanics analysis shows that fracture toughness, in addition to depending on young's modulus, flow stress strain hardening exponent, and yield strain, should be nearly proportoinal to the effective fracture ductility obtained for the stress state characteristic for region ahead of the crack; plane stress or plane strain. It's known that, in most ductile materials, crack propagation of the material strongly governed by the $J_{IC}$ value, which is still difficult to determine for it's complicate and treble-some determinative process. This paper, on the assumption that, initiation of crack tip strain field reaches on the relationships between the critical value of J-integral ($J_{IC}$) and the local fracture strain(${\varepsilon}_c$) in uniaxial tensile test in the region of maximun reduction areas was described.

• Journal of Ship and Ocean Technology
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• 제12권2호
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• pp.1-15
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• 2008

The main idea of this paper introduce stochastic structural parameters and random dynamic excitation directly into the dynamic functional variational formulations, and developed the nonlinear dynamic analysis of a stochastic variational principle and the corresponding stochastic finite element method via the weighted residual method and the small parameter perturbation technique. An interpolation method was adopted, which is based on representing the random field in terms of an interpolation rule involving a set of deterministic shape functions. Direct integration Wilson-${\theta}$ Method was adopted to solve finite element equations. Numerical examples are compared with Monte-Carlo simulation method to show that the approaches proposed herein are accurate and effective for the nonlinear dynamic analysis of structures with random parameters.

• Journal of Genetic Medicine
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• 제18권1호
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• pp.16-23
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• 2021

GLB1-related disorders comprise two phenotypically unique disorders: GM1 gangliosidosis and Morquio B disease. These autosomal recessive disorders are caused by b-galactosidase deficiency. A hallmark of GM1 gangliosidosis is central nervous system degeneration where ganglioside synthesis is highest. The accumulation of keratan sulfate is the suspected cause of the bone findings in Morquio B disease. GM1 gangliosidosis is clinically characterized by a neurodegenerative disorder associated with dysostosis multiplex, while Morquio B disease is characterized by severe skeletal manifestations and the preservation of intelligence. Morquio B disease and GM1 gangliosidosis may be on a continuum of skeletal involvement. There is currently no effective treatment for GLB1-related disorders. Recently, multiple interventions have been developed and there are several ongoing clinical trials.

• Educational Technology International
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• 제9권1호
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• pp.1-23
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• 2008

Despite considerable commitment to the application of action learning as an organization development intervention, no identified systematic investigation of action learning practices has been reported. Based on a systematic literature review, the purpose of this paper is to identify whether researchers strike a balance between action and learning in their studies of action learning. Research findings in this study included: (1) only 32 empirical studies were found from the electronic database search; (2) based on the hypothesized continuum of Revans' original proposition of balancing action and learning, the author categorized 32 studies into three groups: action-oriented, learning-oriented, and balanced action learning; (3) there were only nine studies on balanced action learning among 32 empirical studies, whose insights included an effective use of project teams, applications of action learning for organization development, and key success factors such as time, reflection, and management support; (4) case study was among the most frequently used research method and only six quality studies met key methodological traits; and (5) therefore, more rigorous empirical research employing quantitative methods as well as case studies is needed to determine whether researchers strike a balance between action and learning in studies on action learning.

• Steel and Composite Structures
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• 제51권3호
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• pp.261-270
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• 2024

This paper proposes an effective method for optimizing the structure of functionally graded isotropic and incompressible linear elastic materials. The main emphasis is on utilizing a specialized polytopal composite finite element (PCE) technique capable of handling a broad range of materials, addressing common volumetric locking issues found in nearly incompressible substances. Additionally, it employs a continuum model for bi-directional functionally graded (BFG) material properties, amalgamating these aspects into a unified property function. This study thus provides an innovative approach that tackles diverse material challenges, accommodating various elemental shapes like triangles, quadrilaterals, and polygons across compressible and nearly incompressible material properties. The paper thoroughly details the mathematical formulations for optimizing the topology of BFG structures with various materials. Finally, it showcases the effectiveness and efficiency of the proposed method through numerous numerical examples.