• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.583-592
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams exposed to concentrated harmonic and non-harmonic time-dependent external excitations, incorporating a number of nonclassical effects of transverse shear, primary and secondary warping, and anisotropy of constituent materials are derived. The forced vibration response characteristics of a composite H-type cross-section beam exhibiting the circumferentially asymmetric stiffness(CAS) configuration are exploited in connection with the structural bending-torsion coupling resulting from directional properties of fiber reinforced composite materials.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.156-160
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• 2007

Surface plasmon resonance(SPR) has been widely studied for biological and chemical sensing applications. The present study conducts numerical simulation for the single and bimetallic layer SPR configurations by using the multiple beam interference matrix(MBIM) method to investigate the influence of wave interference and complex refractive indices of materials on optical characteristics such as reflectance and optical phase shift which are used for sensing. First, calculated reflectances are compared with experimental data for validation. In addition, in the single film structures this study finds out the appropriate film thicknesses with minimum reflectance for cases of gold film and silver film. For a bimetallic silver-gold film structure, in particular, the bimetallic film thicknesses that has the minimum reflectance are found 36 nm for silver and 5 nm for gold. From the results, the use of phase shift would be useful compared to reflectance in determining the SPR configuration because the phase shift becomes more sensitive than reflectance.

• Structural Engineering and Mechanics
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• v.40 no.3
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• pp.347-371
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• 2011

This paper focuses on post-buckling analysis of Timoshenko beams with various boundary conditions subjected to a non-uniform thermal loading by using the total Lagrangian Timoshenko beam element approximation. Six types of support conditions for the beams are considered. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. As far as the authors know, there is no study on the post-buckling analysis of Timoshenko beams under uniform and non-uniform thermal loading considering full geometric non-linearity investigated by using finite element method. The convergence studies are made and the obtained results are compared with the published results. In the study, the relationships between deflections, end rotational angles, end constraint forces, thermal buckling configuration, stress distributions through the thickness of the beams and temperature rising are illustrated in detail in post-buckling case.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.96-103
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• 2000

This research is a new design method, which will be presented as a basic concept for a more efficient minimum weight design of grillages, as an attempt to describe true collapse mechanism in as overall search as possible. It serves as introduction to the numerical technique of Linear Programming(LP) and Automatic Modified Direct Plastic Frame Analysis(AMDPFA). Attention is directed to both analysis and design, and emphasis is placed on the physical significance of Systematic Searching Techniques(SST) involved. In weight minimum grillages design, the parameterisation study in optimum beam configuration which was carried out over the range of beam sections for a given plastic section modulus likely to occur in structures by suing an adaptive stochastic optimisation technique, Genetic Algorithms.

• ETRI Journal
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• v.20 no.2
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• pp.231-240
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• 1998

We report, for the first time, the fabrication of vertically stacked InGaAs/GaAs quantum wires (QWRs) on V-grooved substrates by chemical beam epitaxy (CBE). To fabricate the vertically stacked QWRs structure, we have grown the GaAs resharpening barrier layers on V-grooves with (100)-(322) facet configuration instead of (100)-(111) base at 450 $^{\circ}C$. Under the conditions of low growth temperature, the growth rate of GaAs on the (322) sidewall is higher than that at the (100) bottom. Transmission electron microscopy verifies that the vertically stacked InGaAs QWRs were formed in sizes of about $200{\AA} {\times} 500{\sim}600 {\AA}$. Three distinct photoluminescence peaks related with side-quantum wells (QWLs), top-QWLs and QWRs were observed even at 200 K due to sufficient carrier and optical confinement. These results strongly suggest the existence of the quantized state in the vertically stacked InGaAs/GaAs QWRs grown by CBE.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1216-1221
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• 2000

Thermally induced vibration response of composite thin walled beams is investigated. The thin-walled beam model incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, 'rotary inertia' and anisotropy of constituent materials. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferentially uniform system(CUS) configuration are exploited in connection with the structural coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated.

• Journal of KSNVE
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• v.10 no.6
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• pp.1022-1028
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• 2000

This paper presents a modeling method for the vibration analysis of rotating cantilever beams considering the elastic foundation effect. Mass and stiffness matrices are derided explicitly by considering coupling effect between stretching and bonding motion. Numerical results show that the bending direction elastic foundation stiffness influences the vibration characteristics significantly in practical range of beam configuration. The ranges of elastic foundation stiffness to avoid the dynamic buckling are also presented. The method presented in this paper can be used to predict the variations of natural frequencies of rotating cantilever beams with elastically restrained root.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.303-310
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• 2002

The bending vibration and thermal flutter instability of spacecraft booms modeled as circular thin-walled beams of closed cross-section and subjected to thermal radiation loading is investigated in this paper. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending-lagwise bending coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. The numerical simulations display deflection time-history as a function of the ply-angle of fibers of the composite materials, damping factor, incident angle of solar heat flux, as well as the boundary of the thermal flutter instability domain. The adaptive control are provided by a system of piezoelectric devices whose sensing and actuating functions are combined and that an bonded or embedded into the host structure.

• Imaging Science in Dentistry
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• v.39 no.4
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• pp.209-212
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• 2009

Bifid mandibular canal can be an anatomic variation. This condition can lead to complication when performing mandibular anesthesia or during extraction of lower third molar, placement of implants and surgery in the mandible. Four patients underwent preoperative imaging for extraction of third molars using CBCT (CB Mercuray, Hitachi, Japan). The axial images were processed with CBworks program 2.1 (CyberMed Inc., Seoul, Korea). The branches for supplying the lower third molar were identified mainly on cross-sectional and panoramic images of CBCT. Since the location and configuration of mandibular canal variations are important in any mandibular surgical procedures, we report 4 cases of bifid mandibular canal with panoramic and the CBCT images.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.191-197
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• 1998

This paper described the dynamic characteristics of 20-story apartment buildings from the results of full-scale measurements and analysis. The natural frequencies and mode shapes are quantified by measuring and analyzing ambient vibrations of the structure and compared with the results from dynamic analysis. Comparison with computed mode shapes and frequencies shows good agreement with the experimental results. It proved that it is important to estimate coupling beam and soil parameters through a comparison of the measured results with calculated results.