• Proceedings of the KSME Conference
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• 2007.05a
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• pp.200-203
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• 2007

Carbon nanotubes (CNTs) have attracted an increasing attention due to their superior mechanical properties and potential application in industries. The strength of CNT has been predicted or calculated through several simulation techniques but actual experiments on stress-strain behavior are rare due to its dimensional limit, nanoscale positioning/manipulation, and instrumental resolution. We have attempted to observe straining responses of a multi-walled carbon nanotube (MWNT) with different growth methods by performing an in-situ tensile testing in a scanning electron microscope. Linear deformation and fracture behaviors of MWNT were successfully observed and its force-displacement curve was also measured from the bending stiffness and displacement of the force sensor and manipulator. We also obtained different tensile load of carbon nanotube with different growth methods.

• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.17-30
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• 1993

A practical multi-spring model is proposed for a nonlinear analysis of reinforced concrete members, especially columns, taking into account the interaction of axial load and bi-directional bending moment. The parameters of the model are determined on the basis of material properties and section geometry. The axial force-moment interaction curve of reinforced concrete sections predicted by the model was shown to agree well with those obtained by the flexural analysis utilizing realistic stress-strain relations of materials. The reliability of the model was also examined with respect to the test of reinforced concrete columns subjected to varying axial load and bi-directional lateral load reversals. The analytical results agreed well with the experiment.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.495-500
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• 2003

The effect of initial combined load on the lateral free vibration of arches is investigated. For the analysis, P-M interaction curves for the arches are obtained. The arches are circular arches which have constant cross-section and simply supported. Also, the arches are subjected both radial uniform distributed load which results in an axial compression on the cross-section and end moments that cause uniform bending action at the same time. All analysis are performed by finite element method based on Kang and Yoo's curved beam theory.

• Journal of Welding and Joining
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• v.10 no.4
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• pp.259-267
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• 1992

In this report, a method to predict the fatigue strength in welded structure member of ship construction is studied considering the effects of statistical characteristics of mild steels and weld toe shapes on the fatigue crack initiation life. The fatigue test under pulsating bending load is carried out with the model specimens of the web frame in double bottom of ship hull. The propriety of the fatigue life curve with probability of failure in the transverse strength members of ship hull construction is confirmed by the comparison with the results of fatigue test on the model of the various transverse strength members.

• Journal of the Korean Ceramic Society
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• v.27 no.3
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• pp.345-354
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• 1990

The densification behaviro and resulting properties of cordierite-aluminium titanate composites containing 5 to 40wt.% aluminium titanate were investigated. Compared with cordierite monolithics a substantial increase of sintering temperature range for composites was observed, which was due to the formation of cordierite and glass phase at relatively low temperatures. The bending strength of composites showed its maximum at 30wt.% aluminium titanate content, which was about 50% increase relative to the cordierite monolithics, then decreased by a small amount at 40wt.% aluminium titanate content. The decrease was explained by the increase of microcracks whose presence was confirmed by the hysteresis of thermal expansion curve of composites. However, the microcracks formed was not severe enough to produce a significant decrease in strength, which was also evidenced by the continuous increase of thermal expansion coefficient up to 40wt.% aluminium titanate content.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.157-162
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• 1997

Silicon Nitride samples with different microstructure were prepared by hot pressing and subsequent heat treatment under N2 gas pressure. The fracture toughness (KIC)of Si3N4 increased with the increase of grain size, but the bending strength of plain specimen($\sigma$F) decreased. The relation between fracture stress($\sigma$c) and equivalent crack length(ae) agreed well with the calculated values by process zone size failure criterion. A probabilistic failure assessment curve is proposed based on both statistical character of $\sigma$F and KIC.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.260-263
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• 2005

Fatigue fracture behavior of a hybrid joint between side-panel and under-frame by riveting and adhesive bonding has been evaluated. Two kinds of joint specimens based on real geometry were fabricated for shearing test as well as bending test. Static and cyclic loadings were used for fatigue assessment. Fatigue fracture results obtained by such experiments were reflected in modifications of design parameters of the hybrid joint.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.107-116
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• 1996

The studies are conducted to investigate the fatigue and fracture, behavior of preflex girder. In this work, the fatigue tests using by constant amplitude fatigue loading and 4-point-loading to maintain pure bending condition in the mid-span of preflex girder will be performed. It is expected from the results of the studies to provide the fatigue strength and the S-N curve of preflex girders. In addition, it will be ensured that fracture initiation occurs in the welded part of horseshoe-type shear connector as well as in other welded joints.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.621-627
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• 1999

This paper presents Raman scattering of liquid water to obtain the characteristics with variation of temperature. Very clear Stokes-Raman signals were observed, which shows H-O vibration stretching and H-O-H vibration bending. The obtained spectrum were processed by FFT filter to extract the noise and base. The spectral shape of the H-O stretching provided a various sensitive signature which allowed temperature to be determined by a curve-fitting technique. Those are Maximum Intensity, Maximum Wave Length, FWHM(Full Width at Half Maximum), PMCR(Polymer Monomer Concentration Ratio) and TSIR(Temperature Sensitive Intensity Ratio). TSIR method shows the highest accuracy of $0.1^{\circ}C$ in mean error and $0.32^{\circ}C$ In maximum error.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.197-204
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• 1988

This thesis studied the flexibility of anchored sheet piles and the behavior of it according to the levels of excavation. The results showed that the bending moment of sheet piles was reduced due to the displacement of walls and the load of anchor and also that Rowe's moment reduction curve was rational. It concluded that the displacement of anchored sheet piles and the soil settlement behind the walls can be reduce by suitable choice of anchor load and wall flexibility.