• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.1102-1107
• /
• 2004

High-speed railway bridges subject to effect of statical loads by temperature change as well as dynamic loads by interaction between vehicle load which run specially fast and behavior of bridges, If suitable longitudinal expansion by temperature change of bridge does not happened, it can cause unhealthy condition for the parts of bridges as well as can generate addition stress to bridges, For these reason, Analysis and Estimation of data about behavior of bridges occupies important factor in that estimate the remaining life of bridges and select the maintenance, repair and retrofit. In this paper, Analysis for the long-term behavior of bridges using Longitudinal displacement and Temperature data that is actuality measured data to the bridges of Seoul-Busan high speed railroad test section has been made.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1992.10a
• /
• pp.73-78
• /
• 1992

It would be much effective that single column type pier is used in concrete slab bridges rather than gravity type pier is used. To determine the longitudinal bonging moment in concrete slab bridges supported by single column type piers, the concept of effective width is applied. By elastic plate theory cooperated with finite element method, the distribution of the longitudinal moment of the slab supported by single column type piers is studied. The main variables are span, width, and thickness of the slab and column section size. Then the analytical results obtained are summarized and analysed to evaluate the maximum longitudinal negative moment by simple beam analysis.

• Korean Journal of Hydrosciences
• /
• v.8
• /
• pp.19-30
• /
• 1997

The hydraulics of flow within the covered reach of urban streams is very complicated due to the accumulation and interference effect of eddies around the multipli piers supporting the covering slab. An extensive experimental study is done to quantitatively estimate the backwater rise effect caused by various arrays of multiple piers. The factors governing the backwater rise are found out to be the contraction ratio due to the piers. Foude number of the flow, longitudinal pier spacing, and the length of the covered reach. For a single section of lateral pier arralyzed and a multiple regression equation derived. The effect of multiple piers, arrayed in both lateral and longitudinal directions. on the backwater rise is analyzed in terms of the contraction ratio. Froude number, longitudinal pier spacing and the total length of the covered reach. A multiple regression equation for the backwater rise estimation is proposed based on the experimental data collected in this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.348-353
• /
• 2008

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.

• ALGAE
• /
• v.20 no.4
• /
• pp.279-293
• /
• 2005

Two new species of Martensia (Delesseriaceae, Rhodophyta) are described from Jeju Island, Korea. Martensia palmata sp. nov. is characterized by the following traits: more or less linearly elongated lobes arising from the distal margin of the flabellate membranous section; intact latticework with coarse and loose mesh; numerous spine-like projections on the leading margin of the latticework; tetrasporangia produced in sori along the entire blade; spermatangia borne in sori on the membranous section and the longitudinal lamellae of the latticework; and cystocarps borne on the margins of the membranous section. Martensia projecta sp. nov. has the following characteristics: subdichotomously furcated blades, with terminal segments slightly attenuated toward the apex; blades with uneven surfaces; basal parts with a multi-layered parenchymatous construction; small and poorlydefined latticework; tetrasporangia and spermatangia produced in sori on the membranous section; and cystocarps borne on the marginal surfaces of the blades. The existence of M. projecta sp. nov. supports the proposal that the genus Opephyllum Schmitz in Schmitz et Hauptfleisch should be assigned to the genus Martensia.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.4
• /
• pp.363-369
• /
• 2009

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.

• Journal of Aerospace System Engineering
• /
• v.12 no.6
• /
• pp.41-49
• /
• 2018

In this study, the theoretical dynamic characteristics of a thin-walled composite beam with a single-cell of chordwise asymmetric cross-section was studied. Mathematical modeling was done by considering the transverse shear effects, the warping restraint effects, the constant taper ratio in the longitudinal direction of the beam, and the geometrical cross-section ratio. The mass coefficients, stiffness coefficients, and Eigen frequencies of the selected section were investigated. In particular, the effects of the taper ratio and cross-section ratio of the model on the Eigen frequencies were analyzed and compared when the asymmetry of the section was considered and the warping function was not corrected.

• Korean journal of communication and information
• /
• v.32
• /
• pp.7-48
• /
• 2006

The study explores how Korea's major newspaper cover about science news, especially how newspaper frame biotechnology news including new source, news construction ways, coverage trend. The research has a research design to find out coverage pattern or model with frame theory. The result shows that the newspaper has some aspect of frame through out the biotechnology development in the section, theme, source, complexity. The section has been expend to the society and international section, while the theme shift from disease or cancer cure to life itself, genome, or stem cell. In the complexity, the biotechnology news stories have been developed a story plot (event-problem-development-solution). In the climax, the news coverage focuses on the explanation of biotechnology news.

• International journal of steel structures
• /
• v.18 no.4
• /
• pp.1363-1372
• /
• 2018

Recently, there have been studies about the increasing effect on the local plate buckling strength of flat plates when longitudinally stiffened with closed-section ribs and an approximate solution to quantitatively estimate these effects were suggested for flat plates. Since there are few studies to utilize such increasing effect on curved panels and a proper design method is not proposed, thus, this study aims to numerically evaluate such effect due to the rotational stiffness of closed-section ribs on curved panels and to propose an approximate method for estimating the buckling strength. Three-dimensional finite element models were set up using a general structural analysis program ABAQUS and a series of parametric numerical analyses were conducted in order to examine the variation of buckling stresses along with the rotational stiffness of closed-section ribs. By using a methodology that combine the strength increment factor due to the restraining effect by closed-section ribs and the buckling coefficient of the panel curvature, the approximate solutions for the estimation of buckling strength were suggested. The validity of the proposed methods was verified through a comparative study with the numerical analysis results.

• Earthquakes and Structures
• /
• v.7 no.4
• /
• pp.463-484
• /
• 2014

Solid piers with a rounded rectangular cross-section are widely used in railway bridges for high-speed trains in China. Compared to highway bridge piers, these railway bridge piers have a larger crosssection and less steel reinforcement. Existing material models cannot accurately predict the seismic behavior of this kind of railway bridge piers. This is because only a few parameters, such as axial load, longitudinal and transverse reinforcement, are taken into account. To enable a better understanding of the seismic behavior of this type of bridge pier, a simultaneous influence of the various parameters, i.e. ratio of height to thickness, axial load to concrete compressive strength ratio and longitudinal to transverse reinforcements, on the failure characteristics, hysteresis, skeleton curves, and displacement ductility were investigated. In total, nine model piers were tested under cyclic loading. The hysteretic response obtained from the experiments is compared with that obtained from numerical studies using existing material models. The experimental data shows that the hysteresis curves have significantly pinched characteristics that are associated with small longitudinal reinforcement ratios. The displacement ductility reduces with an increase in ratio of axial load to concrete compressive strength and longitudinal reinforcement ratio. The experimental results are largely in agreement with the numerical results obtained using Chang-Mander concrete model.