• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.146-153
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• 2004

This paper presents a discrete analysis approach to investigate the performance of dual mass flywheel (DMF). In the discrete analysis, arcspring installed between the flywheels is modeled as N- discrete elements. Each element consists of mass, spring and nonlinear friction element. LuGre friction model is used to describe nonlinear friction characteristic. Based on the dynamic models of the DMF, clutch, engine, manual transmission and vehicle, a DMF performance simulator is developed using MATLAB Simulink. Simulation results of the engine speed, driveshaft torque and vehicle velocity are compared with test results. It is found that the discrete DMF model describes the vehicle behavior closely, especially during the clutch actuation period.

• Journal of Radiation Protection and Research
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• v.17 no.1
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• pp.43-56
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• 1992

As one of the methods to ameliorate the ray effects which are the nature of anomalous computational effects due to the discretization of the angular variable in discrete ordinates approximations, a computational program, named TWODET (TWO dimensional Discrete Element Transport), has developed in 2 dimensional cartesian coordinates system using the discrete elements method, in which the discrete angle quadratures are steered by the spatially dependent angular fluxes. The results of the TWODET calculation with K-2, L-3 discrete angular quadratures, in the problem of a centrally located, isotropically emitting flat source in an absorbing square, are shown to be more accurate than that of the DOT 4.3 calculation with S-10 full symmetry angular quadratures, in remedy of the ray effect at the edge flux distributions of the square. But the computing time of the TWODET is about 4 times more than that of the DOT 4.3. In the problem of vacuum boundaries just outside of the source region in an absorbing square, the results of the TWODET calculation are shown severely anomalous ray effects, due to the sudden discontinuity between the source and the vacuum, like as the results of the DOT 4.3 calculation. In the probelm of an external source in an absorbing square in which a highly absorbing medium is added, the results of the TWODET calculation with K-3, L-4 show a good ones like as, somewhat more than, that of the DOT 4.3 calculation with S-10.

• Structural Engineering and Mechanics
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• v.83 no.2
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• pp.207-227
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• 2022

In general, the interaction conditions between the discrete stones are not taken into account by structural engineers during the modeling and analyzing of historical stone bridges. However, many structural damages in the stone bridges occur due to ignoring the interaction conditions between discrete stones. In this study, it is aimed to examine the seismic behavior of a historical stone bridge by considering the interaction stiffness parameters between stone elements. For this purpose, Tokatli historical stone arch bridge was built in 1179 in Karabük-Turkey, is chosen for three-dimensional (3D) seismic analyses. Firstly, the 3D finite-difference model of the Tokatli stone bridge is created using the FLAC3D software. During the modeling processes, the Burger-Creep material model which was not used to examine the seismic behavior of historical stone bridges in the past is utilized. Furthermore, the free-field and quiet non-reflecting boundary conditions are defined to the lateral and bottom boundaries of the bridge. Thanks to these boundary conditions, earthquake waves do not reflect in the 3D model. After each stone element is modeled separately, stiffness elements are defined between the stone elements. Three situations of the stiffness elements are considered in the seismic analyses; a) for only normal direction b) for only shear direction c) for both normal and shear directions. The earthquake analyses of the bridge are performed for these three different situations of the bridge. The far-fault and near-fault conditions of 1989 Loma Prieta earthquake are taken into account during the earthquake analyses. According to the seismic analysis results, the directions of the stiffness parameters seriously changed the earthquake behavior of the Tokatli bridge. Moreover, the most critical stiffness parameter is determined for seismic analyses of historical stone arch bridges.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.3
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• pp.203-209
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• 2010

Since information systems are pervasive in the business and non-business areas, the issue of extending researches on information systems to knowledge systems and e-business systems is one of the most profitable topics of researches. We propose a historical, discontinuous changes introducing ambiguity in explaining and interpreting innovative nature of three paradigms of systems: information systems, knowledge systems, and e-business systems. Resorting to the historical perspective in developing ideas into meaningful themes, we proposed a discrete continuity in interpreting changes of paradigms of systems. Discrete continuity may be explained by ambiguously-shared meaningful perspectives applied to different paradigms of systems and interpretive elements of each system. The discrete continuity has been adopted to make ambiguity utilized have instrumental contribution in researches. The engrafted ambiguity in systems design, development, and use could have enduring instrumental value in interpreting the types or variants of systems in each paradigm of systems.

• Journal of Korean Association for Spatial Structures
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• v.6 no.3 s.21
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• pp.87-92
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• 2006

This paper is a study on the experiment and elasto-plastic discrete limit analysis of reinforced concrete circular cylindrical shell by the rigid-bodies spring model. In the rigid bodies-spring model, each collapsed part or piece of structures at the limiting state of loading is assumed to behave like rigid bodies. The present author propose new discrete elements for elasto-plastic analysis of cylindrical shell structures, that is, a rectangular-shaped cylindrical element and a rhombus-shaped cylindrical element for the improvement and expansion of this rigid-bodies spring model. In this study, it is proposed how this rigid element-bodies spring model can be applied to the elasto-plastic discrete limit analysis of cylindrical shell structures. Some numerical results of elasto-plastic discrete limit analysis and experimental results such as the curve of load-displacement and the yielding and fracturing pattern of circular cylindrical shell under horizontal load are shown.

• Computers and Concrete
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• v.16 no.4
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• pp.587-604
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• 2015

The hybrid-type penalty method (HPM) is suitable for representing failure phenomena occurring during the transition from continua to discontinua in materials such as concrete. Initiation and propagation of dominant cracks and branching of cracks can easily be modeled as a discrete crack. The HPM represents a discrete crack by eliminating the penalty that represents the separation of the elements at the intersection boundary. This treatment is easy because no change in the degrees of freedom for the discrete crack is necessary. In addition, it is important to evaluate the correct deformation of the continua before the crack formation is initiated. To achieve this, we implemented a constitutive model of concrete for the HPM. In this paper, we explain the implemented constitutive model and describe the simulation of an anchor bolt pullout test using the HPM demonstrating its capability for evaluating progressive failure.

• Journal of the Korea Society of Computer and Information
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• v.18 no.8
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• pp.87-93
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• 2013

A baby-step giant-step algorithm divides n by n blocks that possess $m={\lceil}\sqrt{n}{\rceil}$ elements, and subsequently computes and stores $a^x$ (mod n) for m elements in the 1st block. It then calculates mod n for m blocks and identifies each of them with those in the 1st block of an identical elemental value. This paper firstly proposes a modified baby-step giant-step algorithm that divides ${\lceil}m/2{\rceil}$ blocks with m elements applying $a^{{\phi}(n)/2}{\equiv}1(mod\;n)$ and $a^x(mod\;n){\equiv}a^{{\phi}(n)+x}$ (mod n) principles. This results in a 50% decrease in the process of the giant-step. It then suggests a reverse baby-step giant step algorithm that performs and saves ${\lceil}m/2{\rceil}$ blocks firstly and computes $a^x$ (mod n) for m elements. The proposed algorithm is found to successfully halve the memory and search time of the baby-step giant step algorithm.

• Structural Engineering and Mechanics
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• v.36 no.3
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• pp.343-361
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• 2010

The Discrete Element Method adopting particles for the domain discretization has recently been adopted in fracture studies of non-homogeneous continuous media such as concrete and rock. A model is proposed in which the reinforcement is modelled by 1D rigid-spring discrete elements. The rigid bars interact with the rigid circular particles that simulate the concrete through contact interfaces. The DEM enhanced model with reinforcement capabilities is evaluated using three point bending and four point bending tests on reinforced concrete beams without stirrups. Under three point bending, the model is shown to reproduce the expected final crack pattern, the crack propagation and the load displacement diagram. Under four point bending, the model is shown to match the experimental ultimate load, the size effect and the crack propagation and localization.

• Coupled systems mechanics
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• v.7 no.1
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• pp.43-59
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• 2018

The presence of the pore fluid strongly influences the reponse of the soil subjected to external loading and in many cases increases the risk of final failure. In this paper, we propose the use of a discrete beam lattice model with the aim to investigate the coupling effects of the solid and fluid phase on the response and failure mechanisms in the saturated soil. The discrete cohesive link lattice model used in this paper, is based on inelastic Timoshenko beam finite elements with enhanced kinematics in axial and transverse direction. The coupling equations for the soil-pore fluid interaction are derived from Terzaghi's principle of effective stresses, Biot's porous media theory and Darcy's law for fluid flow through porous media. The application of the model in soil mechanics is illustrated through several numerical simulations.

• Computers and Concrete
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• v.12 no.1
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• pp.19-36
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• 2013

In the finite element analysis of reinforced concrete structures, discrete representation of the steel reinforcing bars is considered advantageous over smeared representation because of the more realistic modelling of their bond-slip behaviour. However, there is up to now limited research on how to simulate the dowel action of discrete reinforcing bars, which is an important component of shear transfer in cracked concrete structures. Herein, a numerical model for the dowel action of discrete reinforcing bars is developed. It features derivation of the dowel stiffness based on the beam-on-elastic-foundation theory and direct assemblage of the dowel stiffness matrix into the stiffness matrices of adjoining concrete elements. The dowel action model is incorporated in a nonlinear finite element program based on secant stiffness formulation and application to deep beams tested by others demonstrates that the incorporation of dowel action can improve the accuracy of the finite element analysis.