• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.118-122
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• 2002

A numerical study using linear finite element analysis is performed to investigate the behavior of basement wall subject to soil and water pressure. Currently, structural design of basement wall is based on the assumption for boundary condition of plate, which may lead to the erroneous results. In this study, parametric studies are performed to investigate the variation of moment and shear force according to column-to-wall stiffness ratios and aspect ratios. Scaled factors applicable to the design of basement wall are proposed with the illustration of desist examples.

• Solar Energy
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• v.12 no.1
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• pp.95-102
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• 1992

A small scale solar collector system composed of a Fresnel lens of $0.5m^2$ area as a solar concentrator and a compact fluidized-bed solar receiver was developed. Performance and temperature distribution in the fluidized bed receiver were measured using SiC for particles and air for working fluid. The maximum gas temperature was attained up to 1250K at this moment. In this study, energy efficiency achieved by the present experiment was high for the small scale solar collector system and compact receiver.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.47-54
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• 2011

A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially propeller effect on the wing surface is much more dominant when aircrafts are in landing or take-off conditions. In the present paper, three dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out for medium sized turboprop aircraft. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion between moving and static bodies. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift by eliminating local flow separation region and this enhancement was more dominant with high lift device.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.229-232
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• 2002

This study was conducted to estimate the design flood by the determination of best fitting order of LH-moments of the annual maximum series at six and nine watersheds in Korea and Australia, respectively. Adequacy for flood flow data was confirmed by the tests of independence, homogeneity, and outliers. Gumbel (GUM), Generalized Extreme Value (GEV), Generalized Pareto (GPA), and Generalized Logistic (GLO) distributions were applied to get the best fitting frequency distribution for flood flow data. Theoretical bases of L, L1, L2, L3 and L4-moments were derived to estimate the parameters of 4 distributions. L, L1, L2, L3 and L4-moment ratio diagrams (LH-moments ratio diagram) were developed in this study.

• Wind and Structures
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• v.4 no.1
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• pp.63-72
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• 2001

This paper presents results of a study on wind loads and wind induced dynamic response of bridge jointed twin-towered buildings. Utilizing the high-frequency force balance technique, the drag and moment coefficients measured in wind tunnel tests, and the maximum acceleration rms values on the top floor of towers, are analyzed to examine the influence of building's plan shapes and of intervals between towers. The alongwind, acrosswind and torsional modal force spectra are investigated for generic bridge jointed twin-towered building models which cover twin squares, twin rhombuses, twin triangles, twin triangles with sharp corners cut off, twin rectangles and individual rectangle with the same outline aspect ratio as the twin rectangles. The analysis of the statistical correlation among three components of the aerodynamic force corroborated that the correlation between acrosswind and torsional forces is significant for bridge jointed twin-towered buildings.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.35-52
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• 2002

It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method).

• Structural Engineering and Mechanics
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• v.51 no.6
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• pp.1017-1036
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• 2014

Steel tubes have an efficient shape with large second moment of inertia relative to their light weight. One of the main problems of these members is their low buckling resistance caused from having thin walls. In this study, steel foams with high strength over weight ratio is used to fill the steel tube to beneficially modify the response of steel tubes. The linear eigenvalue and plastic collapse FE analysis is done on steel foam filled tube under pure compression and three point bending simulation. It is shown that steel foam improves the maximum strength and the ability of energy absorption of the steel tubes significantly. Different configurations with different volume of steel foam and composite behavior is investigated. It is demonstrated that there are some optimum configurations with more efficient behavior. If composite action between steel foam and steel increases, the strength of the element will improve, in a way that, the failure mode change from local buckling to yielding.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.310-313
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• 2001

This study was conducted to derive optimal design floods by Gumbel, GEV, GLO and GPA distributions for the annual maximum series at sixteen watersheds. Adequacy for the analysis of flood data used in This study was established by the tests of Independence, Homogeneity, detection of Outliers. Parameters were estimated by the Methods of L, L1 and L2-moments. Design floods obtained by Methods of L, L1 and L2-moments using Gringorten methods for plotting positions in GEV distribution were compared by the Relative Mean Errors and Relative Absolute Errors.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.193-195
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• 2006

In this study, we developed an active controlled ankle-foot orthosis(AAFO) which can control the dorsiflexion/plantarflexion of the ankle joint during gait to prevent foot drop and toe drag for paralysis patients. To prevent dropping foot after heel strike, ankle joint was actively controlled to minimize forefoot collision with the ground. It was also controlled to provide toe clearance and to help push-off during late stance. The 3D gait analysis was performed on two healthy subjects equipped with the developed AAFO to compare with the normal gait and the conventional AFO gait. In the developed AAFO gait, differently from the conventional AFO gait, significant push-off was observed during pre-swing and the maximum flexion moment during pre-swing phase was similar to that of normal gait. A remarkable dorsiflexion also occurred during initial swing. These results indicated that the developed AAFO could have certain clinical benefits to prevent foot drop for paralysis patients, compared to conventional AFOs.

• Interaction and multiscale mechanics
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• v.5 no.4
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• pp.369-383
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• 2012

In this paper, soil-structure interaction analysis has been presented for beams resting on multilayered geosynthetic-reinforced granular fill-soft soil system. The soft soil and geosynthetic reinforcements are idealized as nonlinear springs and elastic membranes, respectively. The governing differential equations are solved by finite difference technique and the results are presented in non-dimensional form. It is observed from the study that use of geosynthetic reinforcement is not very effective for maximum settlement reduction in case of very rigid beam. Similarly the reinforcements are not effective for shear force reduction if the granular fill has very high shear modulus value. However, multilayered reinforced system is very effective for bending moment and differential settlement reduction.