• Structural Engineering and Mechanics
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• v.47 no.6
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• pp.773-790
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• 2013

Bending behaviors of corroded reinforced concrete (RC) beams under repeated loading were investigated experimentally. A total of twenty test specimens, including four non-corrosion and sixteen corrosion reinforced concrete beams, were prepared and tested. A numerical model for flexural and cracking behaviors of the beam under repeated loading was also developed. Effects of steel corrosion on reinforced concrete beams regarding cracking, mid-span deflection, stiffness and bearing capacity of corroded beams were studied. The impact of corrosion on bond strength as the key factor was investigated to develop the computational model of flexural capacity. It was shown from the experimental results that the bond strength between reinforcement and concrete had increased for specimen of low corrosion levels, while this effect was changed when the corrosion level was higher. It was indicated that the bearing capacity of corrosion beam increased even at a corrosion level of about 5%.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.108-111
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• 2003

The Objective of this work was to design Surface Antenna Structure (SAS) and investigate fatigue behavior of SAS that was asymmetric sandwich structure. This term, SAS, indicates that structural surface becomes antenna. Constituent materials were selected considering electrical properties, dielectric constant and tangent loss as well as mechanical properties. For the antenna performance, SSFIP elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was $16\;{\times}\;8$ array antenna. From electrical measurements, it was shown that antenna performances were in good agreement with design requirements. In cyclic 4-point bending, flexure behavior was investigated by static and fatigue test. Fatigue life curve of SAS was obtained. The fatigue load was determined experimentally at a 0.75(1.875kN) load level. SAS concept is the first serious attempt at integration for both antenna and composite engineers and promises innovative future communication technology.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.25-32
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• 1988

A formulation of an isoparametric quadrilateral higher-order plate bending finite element is presented. The 8-noded 28-d.o.f. plate element has been degenerated from the three-dimensional continuum by introducing the plate assumptions and considering higher-order in-plane displacement profile. The element characteristics have been derived by the Galerkin's weighted residual method and computed by using the selective reduced integration technique to avoid shear-locking phenomenon. Several numerical examples are given to demonstrate the accuracy and versatility of the proposed quadrilateral higher-order plate bending element over the other existing plate finite elements in both static and dynamic analyses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.959-963
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• 1996

Hardened layer and compressive residual stress created by carburized treatment effect on bending fatigue strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs compared to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.303-310
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• 2002

The bending vibration and thermal flutter instability of spacecraft booms modeled as circular thin-walled beams of closed cross-section and subjected to thermal radiation loading is investigated in this paper. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending-lagwise bending coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. The numerical simulations display deflection time-history as a function of the ply-angle of fibers of the composite materials, damping factor, incident angle of solar heat flux, as well as the boundary of the thermal flutter instability domain. The adaptive control are provided by a system of piezoelectric devices whose sensing and actuating functions are combined and that an bonded or embedded into the host structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.121-129
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• 1997

Bellows are suggested as energy absorbing elements for automotive steering systems. A metallic bellows has nearly constant axial collapse load which is desirable as an energy absorbing element for a steering column. Axial collapsability and bending flexibility of bellows can be utilized to reduce upward tilting and backward displacement of steering columns in the early stage of high speed crash. Since bending flexibility of bellows has negative effects on the vibration characteristics of steering columns it is necessary to maximize the first natural frequency of a bellows while maintaining its plastic bending flexibility and axial collapse load. An effort is made to attain optimum design of bellows based upon the Taguchi method. A general guideline for design of bellows is suggested.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.51-55
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• 2000

The woodceramics which are new porous carbon materials were obtained by carbonizing from thinned small log of Aomori HIBA (Thujopsis dolabrata S. et. Z. var. hondae M.) impregnated with phenol resin in a vacuum furnace. During the carbonization process, the resin changes into glassy carbon, which has superior property. The resin impregnation rate and bending strength depend on the types of board and density. In this paper, the manufacturing method of woodceramics made from thinned small logs of Aomori HIBA was introduced and some properties were examined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.3-6
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• 2003

The electrical and mechanical properties of dielectric paper and cable at cryogenic temperature have been investigated to optimum insulating design of high-Tc superconducting(HTS) cable. From the results, Tensile strength of PPLP in liquid nitrogen was high more than that of air, but tensile strain could know that decrease sharply. According as tensile strength increases, the breakdown stress of PPLP in liquid nitrogen was decreased because PPLP was degradated. According as bending radius multiple is decrese, breakdown voltage decreased sharply. And bending radius multiple is thought that more than about 25 is suitable.

• Steel and Composite Structures
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• v.8 no.4
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• pp.297-312
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• 2008

A concrete filled double skin tubular (called CFDST in abbreviation) member consists of two concentric circular steel tubes and filled concrete between them. Purpose of this study is to investigate their bending characteristics experimentally. The two test parameters of the tubes considered were an inner-to-outer diameter ratio and a thickness-diameter ratio. As a result, their observed failure modes were controlled by tensile cracking or local buckling of the outer tube. Discussion is focused on the confinement effect on the filled concrete due to the both tubes and also the influence of the inner-to-outer diameter ratios on their deformability and load carrying capacity.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.226-231
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• 2003

There have been many attempts to make kart chassis domestically to lower the price of complete kart. However nobody made a successful chassis due to the lack of understanding the characteristics of kart chassis frame. In this work, a baseline chassis frame under the bending and torsional load is studied. Design target is that the baseline chassis frame is quite adequate not only for the beginners but also for the beginning racers. Results from the analysis are used as a guide to design or modify the baseline chassis with the goal of proper torsional stiffness. Minimum increase in weight is being forced. As a result, the baseline chassis frame was designed, made, and tested. Based on the design results, complete karts are being manufactured by the small 1 size domestic company and these karts are being sold and run in the market.