• Bulletin of the Society of Naval Architects of Korea
• /
• v.25 no.4
• /
• pp.47-57
• /
• 1988

A new discrete method using idealized rigid body-spring model is introduced. This rigid element method is known to be more efficient and accurate than the finite element method in the inelastic range of structural analysis owing to simplified stress-strain and strain-displacement relations This kind of physical concept using idealized rigid model has been already applied among structural engineers to some problems such as rigid-plastic analysis or plastic design considering rigid bodies and plastic hinges. However the most rigorous and systematic research has been recently performed by T. Kawai et al.[1]. In this paper, an attempt is made to analyze the collapse behavior of stiffened plates under lateral loading by some modification and expansion of Kawai's rigid element approach to the collapse of plates without stiffener. Stiffened plates are treated as orthotropic plates which have equivalent bending rigidities. By employing Morley's plate element resubdivision technique, variety is given to mesh-division styles which have greate effect on the accuracy of numerical results. Some examples are shown to verify the validity of applying rigid element method to the ultimate strength analysis of stiffened plates. It is clarified that lateral deflections and detailed collapse patterns up to the ultimate state of stiffened plates can be easily obtained by the present approach.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.3
• /
• pp.492-497
• /
• 2015

An overhead rigid conductor system is mainly applied to the subway and recently studies on the rigid system have been conducted for applications such as tunnels of high-speed line and speed improvement of a conventional lines up to 250km/h. Power feeding performance which is the most important in a rigid system can be measured by contact force and characteristics of this contact force are related to the shape and material of the R-BAR. In this paper, we analyze the measurements of contact force, current heating temperature, impedance of a rigid conductor which was developed in Korea, after that we compare static characteristics of home and abroad rigid conductors which have various shapes and materials.

• Structural Engineering and Mechanics
• /
• v.70 no.2
• /
• pp.221-231
• /
• 2019

This paper performs for the first time a simultaneous optimization for members sections along with semi-rigid beam-to-column connections for space steel frames with fixed, semi-rigid, and hinged bases using a biogeography-based optimization algorithm (BBO) and a genetic algorithm (GA). Furthermore, a member's sections optimization for a fully fixed space frame is carried out. A real and accurate simulation of semi-rigid connection behavior is considered in this study, where the semi-rigid base connections are simulated using Kanvinde and Grilli (2012) nonlinear model, which considers deformations in different base connection components under the applied loads, while beam-to-column connections are modeled using the familiar Frye and Morris (1975) nonlinear polynomial model. Moreover, the $P-{\Delta}$ effect and geometric nonlinearity are considered. AISC-LRFD (2016) specification constraints of the stress and displacement are considered as well as section size fitting constraints. The optimization is applied to two benchmark space frame examples to inspect the effect of semi-rigidity on frame weight and drift using BBO and GA algorithms.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.1
• /
• pp.17-31
• /
• 2002

The new MPEG-4 video coding standard enables content-based functionalities. Image segmentation is an indispensable process for it. This paper addresses an effective segmentation of non-rigid objects. Non-rigid objects are deformable objects with fuzzy, blurred and indefinite boundaries. So it is difficult to segment deformable objects precisely. In order to solve this problem, we propose an effective segmentation of non-rigid objects using watershed algorithms in still pictures. And we propose an automatic segmentation through intra-frame and inter-frame segmentation process in video sequences. Automatic segmentation preforms boundary-based and region-based segmentation to extract precise object boundaries.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.1 s.94
• /
• pp.46-52
• /
• 2005

This paper is concerned with the application of perturbation method to the dynamic analysis of free-free beam. In general, the rigid-body motions and elastic vibrations are analyzed separately. However, the rigid-body motions cause vibrations and elastic vibrations also affect rigid-body motions in turn, which indicates that the rigid-body motions and elastic vibrations are coupled in nature. The resulting equations of motion are hybrid and nonlinear. We can discretize the equations of motion by means of admissible functions but still we have to cope with nonlinear equations. In this paper, we propose the use of perturbation method to the coupled equations of motion. The resulting equations consist of zero-order equations of motion which depict the rigid-body motions and first-order equations of motion which depict the perturbed rigid-body motions and elastic vibrations. Numerical results show the efficacy of the proposed method.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.8 no.2
• /
• pp.75-86
• /
• 2004

In this study, a recursive algorithm for generating the equations of motion of a chain of rigid rods is presented. The methods rests upon the idea of replacing the rigid body by a dynamically equivalent constrained system of particles. The concepts of linear and angular momentums are used to generate the rigid body equations of motion without either introducing any rotational coordinates or the corresponding transformation matrices. For open-chain, the equations of motion are generated recursively along the serial chains. For closed-chain, the system is transformed to open-chain by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a closed-chain of rigid rods is chosen to demonstrate the generality and simplicity of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11a
• /
• pp.336.2-336
• /
• 2002

There are many researches to identify the rigid body properties from the mass-line obtained by impact hammer testing. The correct rigid body properties of the structure may be estimated if the mass-line of the structure could be obtained exactly. When the structure is mounted by elastic materials, the mass-line cannot be read correctly from the impulse response spectrum. The reason is due to the effects of rigid body modes of mounted structure. (omitted)

• Structural Engineering and Mechanics
• /
• v.31 no.3
• /
• pp.315-331
• /
• 2009

Mechanical connections are recognized as extremely important elements in the aspect of strength and structural safety. However, classical structural model does not consider the connection stiffness properties, and are based on models with pinned or rigid joints only. In fact, mechanical connections are deformable and behave not linearly, affecting the whole structure and inducing nonlinear behavior as well. The quantification of this effect, however, depends on the description of the working of the connectors and the wood response under embedment. The theoretical modeling of wood structures with semi-rigid connections involves not only the structural analysis, but also the modeling of both single and grouped moment resisting connectors and the study of the wood properties under embedment. The proposal of this paper is to approach these aspects, and to quantitatively study the influence of the moment resistant connection in wooden framed structures. Comparisons between rigid and semi-rigid connections and between linear and nonlinear analysis lead to quantitative results.

• East Asian mathematical journal
• /
• v.31 no.5
• /
• pp.717-725
• /
• 2015

Velzen introduced the rigid and relaxed dominating set games and showed that the rigid game being balanced is equivalent to the relaxed game being balanced in 2004. After then various variants of dominating set games were introduced and it was shown that for each variant, a rigid game being balanced is equivalent to a relaxed game being balanced. It is natural to ask if for any other variant of dominating set game, the balancedness of a rigid game and the balancedness of a relaxed game are equivalent. In this paper, we show that the answer for the question is negative by considering the rigid and relaxed paired-domination games, which is considered as a variant of dominating set games. We characterize the cores of both games and show that the rigid game being balanced is not equivalent to the relaxed game being balanced. In addition, we study the cores of paired-dominations games on paths and cycles.

• Structural Engineering and Mechanics
• /
• v.47 no.6
• /
• pp.857-879
• /
• 2013

Numerical damage assessment of Van train station building consisting of three RC blocks due to 2011 Van Earthquakes by nonlinear dynamic analysis is presented. The structural model is created with rigid-end offsets and plastic hinges for nonlinear analysis. Rigid-end offsets are considered for connection areas and proposed for wall-supported elements. In wall-supported elements, walls take place in a limited part of the columns. Nonlinear dynamic analysis of the building with and without rigid-end offsets is performed by using real earthquake records and results are compared. The results show that rigid-end offsets have significant effects on the seismic behavior of the structures.