• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.2
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• pp.49-58
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• 1997

The objective of this study is to investigate effects of prebuckling on the bucking of laminated compostie cylindrical shells, Both axial compression and lateral pressure are considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. The study was using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.573-578
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• 1999

The reinforced concrete slabs with epoxy-bonded AFRT sheets were experimentally investigated. Experimental data on strength, stiffness, steel strain, deflection and mode of failure of strengthened slabs were obtained, and comparisons between the different flexural reinforcing schemes and reinforced concrete slabs without AFRT sheets were made. The result generally indicate that the flexural strength, ductile behavior of strengthened slabs increased.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.519-524
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• 1999

A bulb-tee sectioned girder is proposed for long span bridge exceeding 40 meters. The proposed bulb-tee girder is developed by non-linear analysis process. This study investigates the structural behavior and efficiency of proposed bulb-tee sectioned girder using 1/2 scaled prototype beam specimen. Three specimens are tested under three point static loading system. The crack patterns, failure mode and ultimate load capacity of each specimen are reported in this paper and they are compared to each other.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.697-700
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• 2000

Fatigue damage to reinforced concrete bridge decks have been found in many bridges. Failure mode of most reinforced concrete decks is caused by local punching shear rather than flexural moment due to cumulated damage. In this study, mechanical degradation of unstrengthened and strengthened bridge deck specimens is experimentally investigated. The unstrengthened deck specimens were damaged under the pulsating loading condition. After the test, deteriorated deck specimens were strengthened with Carbon Fiber Sheet, then loaded to observe the improvement of the fatigue behavior. It is shown that fatigue damaged specimens are similar to real bridge rather than static damaged specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.105-106
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• 2009

The flexural performance of high-strength concrete beams reinforced with steel fibers is described. This study aims at determining the structural behavior of steel fiber reinforced concrete beams such as failure mode, capacity in flexure, crack patterns, strains in concrete.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.64-67
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• 1998

This paper proposes the hybrid PWM scheme that can obtain less harmonic characteristics in GTO inverters. By employing the variable of the dc-link voltage Vdc, the hybrid PWM pattern can ideally compensate the dc input fluctuation together with selected harmonics elimination. The transient behavior, which the magnetic flux and torque are altered and the large current flows instantly, may be produced when the mode change. To reduce such an undesirable transient behavior, it is also presented the technique for the gear changing of inverter operated with the hybrid PWM. The results are verified by simulations and experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.101-102
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• 2010

The flexural performance of high-strength prestressed concrete (PSC) beams reinforced with steel fibers is described. This study aims at determining the structural behavior of steel fiber reinforced concrete beams such as failure mode, capacity in flexure, crack patterns, strains in concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.845-850
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• 1998

Flexural tests on 3.0m reinfored concrete beams with epoxy and anchor bolt bonded CFRF-Grid reported in these tests. The selected experimental variables are concrete compressive strength, strengthening length and strengthening method. The effects of these variables in overall behavior are discussed. The results generally shown that the main flexural mode of strengthened beams is separation failure. The strengthening of the chipping by the tensile bar is really necessary in order to prevent CFRP-Grid from rip-off failure.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.9-12
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• 2000

This paper deals with the torsional buckling behavior of plain weave GFRP composite cylindrical shells having comparatively small length-to-diameter ratio. Boundary conditions corresponding to clamped ends and simply supported ends are considered. Torsional buckling loads and circumferential mode numbers according to the variation of shell length-to-radius ratio are conformed. To verify the availability of the theoretical results, comparison with the theoretical and experimental results are made.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.9-15
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• 1996

The characteristics on the extension of the CED(Crack energy density) concept to the interface kinked crack problems in a dissimilar material are examined. Each mode contributions of CED are found by symmetric and antisymmetric components and domain independent integrals. Finite element calculation is carried out to simulate the Interface kinked crack growth on bimaterial. The focus is the establishment of fracture criterion with CED and finding the orientation of crack extension. From the results, a prediction about the extension behavior of an interface kinked crack can be done. And we show that CED can be a parameter to indicate fracture criterion at an Interface kinked crack.