• Steel and Composite Structures
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• v.43 no.3
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• pp.327-340
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• 2022

A vast amount of experimental and analytical research has been conducted related to the seismic behavior and performance of concrete filled steel tubular (CFT) columns. This research has resulted in a wealth of information on the component behavior. However, analytical and experimental data for structural systems with CFT columns is limited, and the well-known behavior of steel or concrete structures is assumed valid for designing these systems. This paper presents the development of an analytical model for nonlinear analysis of composite moment resisting frame (CFT-MRF) systems with CFT columns and steel wide-flange (WF) beams under seismic loading. The model integrates component models for steel WF beams, CFT columns, connections between CFT columns and WF beams, and CFT panel zones. These component models account for nonlinear behavior due to steel yielding and local buckling in the beams and columns, concrete cracking and crushing in the columns, and yielding of panel zones and connections. Component tests were used to validate the component models. The model for a CFT-MRF considers second order geometric effects from the gravity load bearing system using a lean-on column. The experimental results from the testing of a four-story CFT-MRF test structure are used as a benchmark to validate the modeling procedure. An analytical model of the test structure was created using the modeling procedure and imposed-displacement analyses were used to reproduce the tests with the analytical model of the test structure. Good agreement was found at the global and local level. The model reproduced reasonably well the story shear-story drift response as well as the column, beam and connection moment-rotation response, but overpredicted the inelastic deformation of the panel zone.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.1-12
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• 2012

In this study, an analysis method for the earthquake response of an offshore wind turbine model is developed, considering the effects of the fluid-structure-soil interaction. The turbine is modeled as a tower with a lumped mass at the top of it. The tower is idealized as a tubular cantilever founded on flexible seabed. Substructure and Rayleigh-Ritz methods are used to derive the governing equation of a coupled structure-fluid-soil system incorporating interactions between the tower and sea water and between the foundation and the flexible seabed. The sea water is assumed to be a compressible but non-viscous ideal fluid. The impedance functions of a rigid footing in water-saturated soil strata are obtained from the Thin-Layer Method (TLM) and combined with the superstructure model. The developed method is applied to the earthquake response analysis of an offshore wind turbine model. The method is verified by comparing the results with reference solutions. The effects of several factors, such as the flexibility of the tower, the depth of the sea water, and the stiffness of the soil, are examined and discussed. The relative significance of the fluid-structure interaction over the soil-structure interaction is evaluated and vice versa.

• Journal of Korean Society of Steel Construction
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• v.21 no.2
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• pp.145-154
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• 2009

This study discusses the inelastic behavior of single-layer latticed dome, which consists of a tubular truss member and newly proposed joint sections, through a loading test on a scaled-down structure. The loading test was performed under displacement control conditions, using loading transfer system for the same value of point loads on all joints. The maximum applied load was nearly 1.6 times of the design load, and structural failure occurred after exceeding the compressive yielding in some members. Structural displacement was maintained up to the limit of the oil jack. The behavior of the latticed dome from the loading test was analyzed according to the order of loading steps.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1613-1616
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• 2012

Ni nanoparticles-$TiO_2$ nanotube arrays (Ni/$TiO_2NTs$) composites were prepared by pulsed electrodeposition method and subsequently characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The FESEM results showed that highly dispersed Ni nanoparticles were not only loaded on the top of the $TiO_2NTs$ but also within the tubular structure, and the particle size of Ni prepared at different current amplitude (100, 200 and 300 $mA{\cdot}cm^{-2}$) was in the range of 15 to 70 nm. The electrochemical studies indicated that Ni nanoparticles loaded on the highly ordered $TiO_2NTs$ are readily accessible for electrochemical reactions, which improve the efficiency of the Ni nanoparticles and $TiO_2NTs$. A maximum specific capacitance (27.3 $mF.cm^{-2}$) was obtained on the Ni/$TiO_2NTs$ composite electrode that prepared at a current of 200 $mA.cm^{-2}$, and the electrode also exhibited excellent electrochemical stability.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.192.1-192.1
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• 2010

Micro hydraulic turbines take a growing interest because of its small and simple structure as well as high possibility of applying to micro and small hydropower resources. The differential pressure exiting within the city water pipelines can be used efficiently to generate electricity like the energy generated through gravitational potential energy in dams. In order to reduce water pressure at the inlet of water cleaning centers, pressure reducing valves are used widely. Therefore, pressure energy is wasted. Instead of using the pressure reduction valve, a micro counter-rotating hydraulic turbine can be replaced to get energy caused by the large differential pressure found in the city water pipelines. In this paper, detail studies have been carried out to acquire basic design data of micro counter-rotating hydraulic turbine, output power, head, and efficiency characteristics on various number of runner vane. Moreover, the influences of pressure, tangential and axial velocity distributions on turbine performance are also investigated.

• Economic and Environmental Geology
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• v.48 no.3
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• pp.247-253
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• 2015

Natural halloysite is mostly found in the form of a tubular structure with a 15-125 nm internal lumen. This kaolin clay can be used for encapsulating a liquid ingredient of cosmetics and for immobilizing an inorganic solid-phase ingredient. In this paper, the encapsulation and immobilization procedures are introduced and two example applications are reviewed to demonstrate the usefulness of halloysite as a cosmetics substrate. It may help attract more interest in cosmetic applications of halloysite and thus spur more research on the utilization of natural clays.

• Korean Journal of Veterinary Research
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• v.29 no.3
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• pp.231-237
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• 1989

Morphological features of the vomeronasal organ of both Korean native cattle and Korean native goat were studied by gross, microscopic and histochemical examinations. Anatomical characteristics of the vomeronasl organ were similar in both Korean native cattle and Korean native goats. The vomeronasal organ is a tubular structure situated bilaterally at the base of the nasal septum, and enclosed by hyaline cartilage. Its lumen is semilunar to crescent in transverse sections. It join with the incisive duct through narrow duct. The lumen of the vomeronasal organ is lined with sensory and respiratory epithelia. The distribution pattern of vomeronasal mucosal epithelia varied by the position. In the anterior portion joining with nasal cavity, the lumen is lined with only respiratory epitheliu. In the middle portion, sensory epithelium appeared on the medial side, and respiratory epithelium on the lateral side. In the posterior, it is lined with sensory epithelium on the ventral side and lined with respiratory epithelium on the dorsal side. The vomeronasal gland composed of mucous and serous acini are distributed in the lamina propria under the respiratory epithelium, where venous sinuses are also well developed.

• Steel and Composite Structures
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• v.28 no.5
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• pp.607-615
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• 2018

The dynamic behavior of the deployment and folding process of a foldable boom based on the Miura origami pattern is investigated in this paper. Firstly, mechanical behavior of a single storey during the motion is studied numerically. Then the deployment and folding of a multi-storey boom is discussed. Moreover, the influence of the geometry parameters and the number of Miura-ori elements n on the dynamic behavior of the boom is also studied. Finally, the influence of the imperfection on the dynamic behavior is investigated. The results show that the angles between the diagonal folds and horizontal folds will have great effect on the strains during the motion. A bistable configuration can be obtained by choosing proper fold angles for a given multi-storey boom. The influence of the imperfection on the folding behavior of the foldable mast is significant.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.25-30
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• 2008

The optical performances of 15-inch edge-lit backlight were simulated by using a Monte Carlo ray-tracing technique. The backlight model was built by combining a wedge-type light guide plate, a diffuser sheet, a tubular fluorescent lamp with a lamp reflector, and two crossed prism sheets. Angular distributions of the luminance on each optical component obtained from simulation were consistent with those obtained from experiments on a real 15-inch backlight. The constructed backlight model was used to evaluate the optical performances of a micro-pyramid film. It was found that the on-axis luminance gain on the pyramid film is higher than that on one prism film but much lower than that on the two crossed prism films. These results suggest that a reliable simulation model can be used to develop new hybrid films and to optimize the optical structure of edge-lit backlight in order to reduce the developmental period.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.491-498
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• 2011

In this paper, extensive structural behavior and effects of design parameters of steel column-base plate connections under axial and lateral loads were investigated to improve structural details of CFT(Concrete Filled Steel Tube) pier foundation using commercial FE analysis program, ABAQUS. For this study, design criteria of pier foundation was analyzed and numerical study based on the experiment of previous study was conducted to verify analysis methods. The failure behavior and stress distribution of pier foundation were analyzed using the verified analysis method. Various design parameters(base plate, deformed bar, stiffness and sizes of column) were investigated to analyze effects of each design parameters in entire structure.