• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.689-694
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• 2003

An iterative modal analysis approach is developed to determine the effect of transverse open cracks on the dynamic behavior of simply supported pipe conveying fluid subject to the moving mass. The equation of motion is derived by using Lagrange's equation. The influences of the velocity of moving mass and the velocity of fluid flow and a crack have been studied on the dynamic behavior of a simply supported pipe system by numerical method. The presence of crack results in higher deflections of pipe. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. Totally, as the velocity of fluid flow and the crack severity are increased, the mid-span deflection of simply supported pipe conveying fluid is increased. The time which produce the maximum dynamic deflection of the simply supported pipe is delayed according to the increment of the crack severity.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.1
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• pp.3-12
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• 1986

This paper investigates the static configurations and the dynamic behaviors of a single point mooring line. To obtain the static configuration and static tension distribution along the mooring line, including the effect of fluid nonlinear drag and the elasticity of the line, the Runge-Kutta fourth order numerical method was used. The relationship between the horizontal excursion and the horizontal restoring force component of the mooring line, which is very important to a mooring line design, and the effect of a subsurface buoy on the static configuration are presented. In nonlinear dynamic analysis including nonlinear fluid drag acting on the line and geometrical nonlinearity for large deflections, finite element method using updated Lagrangian was used to obtain the solution. In the case of upper end harmonic excitation of the mooring line, the dynamic motion and the tension were also presented.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1080-1085
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• 2002

A dynamic characteristics of existing steel plate girder railway bridges without ballast were investigated from the finite element analysis. Span lengths, types of vehicle and running speeds are selected as parameters for analyses. For more exact analysis, it was adopted that 3-dimensional bridge models and wheel loads were produced by averaging field measured wheel loads of running vehicles at various speeds. Dynamic vertical deflections, dynamic amplification factors and vertical accelerations of bridges having 9m, 12m and 18m span length were investigated and compared with the limit values specified in Korean railway bridge specification.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.833-838
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• 1998

This paper is aimed to investigate structural performance of flexural members enlarged with epoxy mortar at soffit. Main test variables are steel ratio and interface treatment method and six test beams are tested to investigate the effect of each test variables on maximum load capacity, load-deflection and moment-curvature relationship, interface behavior and failure mode. Test results show that section enlarged beams can carry almost same load of the monolithic beams with same size and the flexural stiffness and cracking moments are increased about 2.5 times and 50 to 70%of failure moment in comparison with same sized control beam, respectively. However, deflections and curvatures are decreased at the same load and interface fractures are not discovered at the ultimate load.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.706-711
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• 1998

Structural tests of the PSC Beam bridge using high strength concrete, concrete compressive strength 700kg/$\textrm{cm}^2$, are conducted for the application including durability and serviceability of the bridge. Current design safety factors with respect to the jacking force and the service design load DB-24 are applied to the design of the bridge. Concrete compressive strength 700kg/$\textrm{cm}^2$, girder depth 2.3m, girder space 3.2m, span length 20m, and slab thickness 27cm are selected for the bridge test. The Bulb-Tee section of the girders is applied instead of I section because it is well known more stable to the longer span(40m). Static load test(4 beams) with composite and non-composite section, and fatigue load test(1 beams) with composite section are conducted. Crack moment, ultimate load, deflections with load steps, and strains of the beam section for those bridges are investigated. The structural test results of the bridges showed a good performance for a safety and a serviceability.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.442-448
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• 1997

An analytical method based on the nonlinear layered finite element method is developed to simulate the load-dsflection behavior of strengthened beams. Beams considered in this study are the ones strengthened either with external steel plate or Carbon Fiber Sheets(CFS) bonded to the overlay soffit. The theoretically obtained load-deflections and strains of the strengthened beams are compared to the corresponding experimental values. Parametric studies are, then. performed using the developed model to investigate the effects of design variables on the flexural behavior of the strengthened beams. Simply supported beams under monotonically increasing loads sre considered exclusively.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.63-69
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• 2009

This paper provides the engineer with a simple design method dealing with situations arise where in-situ reinforced concrete joints are cast between hollow core units. Using finite element method, hollow core slabs with wide in-situ RC joints under point load and line loads are analysed. In addition, some important behavioural characteristics of the floor slab subjected to line and point loads are investigated. In-situ reinforced concrete joint causes reduction of load distribution for remote units because distance to the remote units from the point of load is increased, while the portion of load distribution carried by loaded unit increases. Also, it was turned out load distribution factors for point load and line loads are almost same. Finally, we suggest a simple analytical method, which can determine load distribution factors using normalized deflections by regression analysis for design purposes.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.46-58
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• 1988

The experimental investigations on the motion characteristics of a marine riser both in air and water were performed. The static deflections and natural frequencies of the riser in air including the effect of static offset, were obtained from the experiment. These results were compared with those of theoretical prediction by using a simple asymptotic formula. In order to investigate the nonlinear motion characteristics of the riser subject to nonlinear viscous drag and large displacement, the forced oscillation tests both in air and water were performed. In the forced oscillation tests in air, it was found that the transverse motion due to geometrical nonlinearity grows when the amplitude of in-line oscillation exceeds a certain critical value, say, order of 1-2 diameters. The planar motions of the riser in water due to vortex shedding and the geometrical nonlinearity were described. Some of these results were also compared with those of theoretical analysis, which uses a numerical perturbation technique based on the derived linear asymptotic solutions, and found to be generally in good agreement.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2533-2535
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• 1998

In this paper, an effect of drive-in process temperature on the residual stress profile of the p+ silicon film has been investigated. The residual stress profile has been calculated as the fourth-order polynomials. All coefficients of the polynomials have been determined from the measurement of the vertical deflections of the p+ silicon cantilevers with various thickness and the tip displacement of the p+ silicon rotating beam. From the determination results of the residual stress profile, the average stress of the film thermally oxidized at 1000 $^{\circ}C$ is 15 MPa and that of the film oxidized at 1100 $^{\circ}C$ is 25 MPa. The profile of the residual stress through the high temperature drive-in process has a steeper gradient than the other case.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.2
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• pp.103-112
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• 2016

Resonance occurrence conditions are explored by performing dynamic interaction analysis of arch bridge and KTX trains. The target bridge is a 3D tied-arch bridge having span length of 120m. KTX trains consist of two power carriages, two power and passenger carriages and sixteen passenger carriages. When KTX trains run on the target bridge with the uniform speed of 100 to 500km/h, the dynamic responses of the bridge induced by moving trains are obtained from railway arch bridge-train interaction analysis. Two resonance conditions are presented and whether the resonance phenomena occur or not at the suspicious resonance velocities is rigorously investigated through bridge deflections and accelerations and their FFT analysis.