• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1996.10a
• /
• pp.37-44
• /
• 1996

When a load such as the mechanical load, the wind load, and the seismic load causing a vibration, acts on the body of the 3-D frameworks with slab, it is required to consider the dynamic behavior of elastic soil as well as that of 3-D structure in the structural analysis. Thus, this study presents the analysis of dynamic behavior using finite element method that is formulated by using a model of the 3-D structure. For the idealization of the actual structure closely into a geometric shape, plate is subdivided into 4-node plate element with the flexibility, beam-column is subdivided into 2-node beam element, and elastic soil is subdivided into 8-node brick element.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.201-202
• /
• 2009

The objective of this paper is to develop nonlinear analysis method using fiber element. The program is based on flexibility method and developed for analyzing bernoulli's beam element. Using fiber element, three dimensional effects, such as concrete confinement can be incorporated into the uniaxial stress-strain relationship. In addition, most appropriate modeling method is used for application of bond-slip and shear effects.

• Proceedings of the ESK Conference
• /
• 1997.10a
• /
• pp.372-375
• /
• 1997

Classivication scheme of usability element for the evaluation of consumer electronic product was developed in this study. Using hierachical structuring and clustering methods, usability element of consumer products interface is developed both for the performance perspective and for the image/appeal perspective of a product. Perfoormance element included variables such as simplicity, directness, learn- ability, flexibility, user support and effectiveness. Image/Appeal element included variables such as sensibility, descriptive impression, evaluation of appeal, and attitude towards the product. The classifi- cation scheme developed in this study is found to be comprehensive and robust relative to other existing paradigms. They can be effectively used and applied for the usability evaluation of consumer electronic products.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.59 no.3
• /
• pp.330-334
• /
• 2010

We tried to combine a transformer with a superconducting element and investigated the current limiting characteristics. When a superconducting element was connected to third winding of the transformer, the fault current was limited to about 90 % effectively. The fault current and consumption power were able to be controlled by the turn's ratio of secondary and third windings. It gives flexibility of the rating of a transformer in the power grid. As a result, power burden of a superconducting element was reduced by the decrease of turn's ratio in third winding of a transformer. It was because the voltage behavior of a superconducting element was dependent on turn's ratio of a transformer while the current characteristic was independent.

• Structural Engineering and Mechanics
• /
• v.75 no.6
• /
• pp.685-699
• /
• 2020

Polygonal finite element provides a great flexibility in mesh generation of crack propagation problems where the topology of the domain changes significantly. However, the control of the discretization error in such problems is a main concern. In this paper, a polygonal-FEM is presented in modeling of crack propagation problems via an automatic adaptive mesh refinement procedure. The adaptive mesh refinement is accomplished based on the Zienkiewicz-Zhu error estimator in conjunction with a weighted SPR technique. Adaptive mesh refinement is employed in some steps for reduction of the discretization error and not for tracking the crack. In the steps that no adaptive mesh refinement is required, local modifications are applied on the mesh to prevent poor polygonal element shapes. Finally, several numerical examples are analyzed to demonstrate the efficiency, accuracy and robustness of the proposed computational algorithm in crack propagation problems.

• Structural Engineering and Mechanics
• /
• v.59 no.2
• /
• pp.243-259
• /
• 2016

This research develops a finite element code for the transient dynamic analysis of tapered fiber reinforced polymer (FRP) poles with hollow circular cross-section and flexible joints used in power transmission lines. The FRP poles are modeled by tapered beam elements and their flexible joints by a rotational spring. To solve the time equations of transient dynamic analysis, precise time integration method is utilized. In order to verify the utilized formulations, a typical jointed FRP pole under step, triangular and sine pulses is analyzed by the developed finite element code and also ANSYS commercial finite element software for comparison. Thereafter, the effect of joint flexibility on its dynamic behavior is investigated. It is observed that by increasing the joint stiffness, the amplitude of the pole tip deflection history decreases, and the time of occurrence of the maximum deflection is earlier.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.6
• /
• pp.197-204
• /
• 2003

This paper presents an efficient modeling and dynamic analysis method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the inconvenience and numerical errors in association with re-meshing the structural model with the crack position changed. The proposed modeling method is validated through a series of simulation and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, two kinds of experiments are performed to validate the proposed modeling method. Finally, a diagnostic scheme fur open cracked beam structures is proposed and demonstrated through a numerical example.

• Structural Engineering and Mechanics
• /
• v.49 no.2
• /
• pp.183-202
• /
• 2014

A new method of multiple damage detection in beam like structures is introduced. The mode shapes of both healthy and damaged structures are used in damage detection process (DDP). Multiple Damage Localization Index Based on Mode Shapes (MDLIBMS) is presented as a criterion in detecting damaged elements. A finite element modeling of structures is used to calculate the mode shapes parameters. The main advantages of the proposed method are its simplicity, flexibility on the number of elements and so the accuracy of the damage(s) position(s), sensitivity to small damage extend, capability in prediction of required number of mode shapes and low sensitivity to noisy data. In fact, because of differential and comparative form of MDLIBMS, using noise polluted data doesn't have major effect on the results. This makes the proposed method a powerful one in damage detection according to measured mode shape data. Because of its flexibility, damage detection process in multi span bridge girders with non-prismatic sections can be done by this method. Numerical simulations used to demonstrate these advantages.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.6 s.99
• /
• pp.749-756
• /
• 2005

This paper presents vibration analyses of hard disk drive (HDD) spindle systems based on the finite element method. The systems under investigation have a cantilevered shaft rotating on hydrodynamic bearings. In particular, the influence of stator's flexibility on major modes has been taken into account in dual ways lumped and distributed-parameter model approfches. Even the latter employs relatively macroscopic elements instead of extremely fine ones Popular in commercial codes. In order to prove the effectiveness of such formulated models, two types of HDD prototypes featuring different hub and stator structures are selected as examples. Compared to the first, the second type has a reinforced stator that would raise the natural frequency of the hub's translational (or sideway) mode. Both free and forced vibration characteristics are computed, and subsequently compared with the experimental data. It is our conclusion that Particularly the Proposed distributed model method is an efficient design tool for state-of-the-art HDD spindle systems.

• Structural Engineering and Mechanics
• /
• v.15 no.6
• /
• pp.629-651
• /
• 2003

Current design specifications prescribe that the upper and lower reinforcement mat is required in the same amount to resist negative and positive moment in bridge decks. This design concept is primarily based on the unrealistic assumption that the girder plays a role of rigid support against deck deflection. In reality, however, girders are flexible and the deflection of girders affect the behavior of deck slabs. In the present study, an analytical method was developed to take the effect of the girder flexibility on the deck behavior into account. The method was formulated based on the slope-deflection equations of plates and harmonic analysis. Unlike the conventional finite element analysis, the input and output schemes are simple and convenient. The validity of the presented study was verified by a series of comparative studies with finite element analyses and experimental tests. It was shown from the analyses that the negative transverse moments of decks were significantly reduced in many cases when the girder flexibility were appropriately taken into consideration whereas the positive moments tend to increase. This poses a strong need to improve the conventional design concept of decks on rigid girders to those on flexible girders.