• Structural Engineering and Mechanics
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• v.71 no.6
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• pp.683-697
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• 2019

The reinforced concrete (RC) structures usually suffer large residual displacements under strong motions. The large residual displacements may substantially reduce the anti-seismic capacity of structures during the aftershock and increase the difficulty and cost of structural repair after an earthquake. To reduce the adverse residual displacement, several self-centering energy dissipation braces (SCEBs) have been proposed to be installed to the RC structures. To investigate the seismic responses of the RC structures with SCEBs under the earthquake excitation, an extended Bouc-Wen model with degradation and self-centering effects is developed in this study. The extended model realized by MATLAB/Simulink program is able to capture the hysteretic characteristics of the RC structures with SCEBs, such as the energy dissipation and the degradation, especially the self-centering effect. The predicted hysteretic behavior of the RC structures with SCEBs based on the extended model, which used the unscented Kalman filter (UKF) for parameter identification, is compared with the experimental results. Comparison results show that the predicted hysteretic curves can be in good agreement with the experimental results. The nonlinear dynamic analyses using the extended model are then carried out to explore the seismic performance of the RC structures with SCEBs. The analysis results demonstrate that the SCEB can effectively reduce the residual displacements of the RC structures, but slightly increase the acceleration.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.45-48
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• 2008

Periodic lattice structures such as the large space lattice structures and carbon nanotubes may take the extension-transverse shear-bending coupled vibrations, which can be well represented by the extended Timoshenko beam theory. In this paper, the spectrally formulated finite element model (simply, spectral element model) has been developed for extended Timoshenko beams and applied to some typical periodic lattice structures such as the armchair carbon nanotube, the periodic plane truss, and the periodic space lattice beam.

• Journal of Korean Association for Spatial Structures
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• v.2 no.1 s.3
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• pp.41-49
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• 2002

In this paper, a study of 2-step damage detection for space truss structures using the extended Kalman filter theory is presented. Space truss structures are composed of many members, so it is difficult to find damaged member from the whole system. Therefore, 2-step damage identification method is applied to detect the damaged members. First, kinetic energy change ratio is used to find damage region including damaged member and then detect damaged member using extended Kalman filtering algorithm in damage region. The effectiveness of proposed method is verified through the numerical examples.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1403-1406
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• 2008

Periodic lattice structures such as the large space lattice structures and carbon nanotubes may take the extension-transverse shear-bending coupled vibrations, which can be well represented by the extended Timoshenko beam theory. In this paper, the spectrally formulated finite element model (simply, spectral element model) has been developed for extended Timoshenko beams and applied to some typical periodic lattice structures such as the armchair carbon nanotube, the periodic plane truss, and the periodic space lattice beam.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.167-176
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• 1999

This paper is concerned with the damage detection of existing 2 and 3-dimensional truss structures based on free vibration equation and extended Kalman filter. The local damage is characterized in terms of the stiffness degradation of damaged members. As the observed data, the natural frequencies and mode shapes of damaged truss structure model are adopted. Both location and stiffness of damaged parts of members in truss structures can be estimated by the proposed inverse solution procedure. The applicability and effectiveness of proposed inverse solution procedure are demonstrated through the numerical examples.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.1-9
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• 2001

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.789-797
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• 2017

Recently, some integrated structural identification/damage detection and reliability evaluation of structures with uncertainties have been proposed. However, these techniques are applicable for off-line synthesis of structural identification and reliability evaluation. In this paper, based on the recursive formulation of the extended Kalman filter, an on-line integration of structural identification/damage detection and reliability evaluation of stochastic building structures is investigated. Structural limit state is expanded by the Taylor series in terms of uncertain variables to obtain the probability density function (PDF). Both structural component reliability with only one limit state function and system reliability with multi-limit state functions are studied. Then, it is extended to adopt the recent extended Kalman filter with unknown input (EKF-UI) proposed by the authors for on-line integration of structural identification/damage detection and structural reliability evaluation of stochastic building structures subject to unknown excitations. Numerical examples are used to demonstrate the proposed method. The evaluated results of structural component reliability and structural system reliability are compared with those by the Monte Carlo simulation to validate the performances of the proposed method.

• Korean Journal of Child Studies
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• v.15 no.2
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• pp.195-211
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• 1994

This study was designed to examine the effects of family structure (nuclear, extended family) on children's behavioral and emotional problems. The subjects of this study were 650 primary school children aged 8 to 13 living in Seoul and Incheon (324 from nuclear and 326 from extended families). The Children's Behaviour Questionnaire (CBQ: Rutter, 1970) and a questionnaire containing demographic questions and some additional questions were used for instruments. For the analyses, frequencies, descriptives, chi-square, factor analysis, and t-test were used. The results were analysed and explained in their cut-off points, prevalences, differences and factor structures. The cut-off score obtained in this study was 18, and the prevalences with this cut-off score were 6.3% in total subjects, 8.0% in nuclear families, and 4.6% in extended families. The children from extended families showed less behavioral and emotional problems, especially antisocial behaviours, compared with those from nuclear families, and this difference was significant (p<.05). The factor structures of the CBQ were 'antisocial', 'neurotic', 'mannerism' and 'speech' in total subjects, and, in the case of nuclear families, the factor structures were same as in total subjects, but, in the case of extended families, the 'emotional anxiety' factor was included instead of the 'speech' factor.

• Current Optics and Photonics
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• v.5 no.6
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• pp.597-605
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• 2021

An extended Fourier modal method (FMM) for optical dipole radiation in three-dimensional photonic structures is proposed. The core elements of the proposed FMM are the stable bidirectional scattering-matrix algorithm for modeling internal optical emission, and a novel optical-dipole-source model that prevents numerical errors induced by the Gibbs phenomenon. Through the proposed scheme, the FMM is extended to model a wide range of source-embedded photonic structures.

• Journal of the Korean Chemical Society
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• v.12 no.3
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• pp.85-88
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• 1968

The resonance parameter value between the saturated carbon and unsaturated carbon atom in cyclopentadiene has been evaluated. And then cyclopentadiene has been investigated on the correlations between it's electronic structures and reactivities by means of the extended Huckel method proposed by R. Hoffmann.