• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.308-308
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• 2006

We have demonstrated that the cylindrical micelles self-assembled from coil-rod-coil molecules can be interconnected by addition of a small amount of rod-coil-rod molecule as a bridging agent. Subsequently, these dynamic interconnections lead to stiff bundles composed of cylindrical micelles that are responsible for the formation of a reversible nematic gel. The results described here represent a significant example that dynamic bridging of supramolecular cylinders in aqueous solution can provide a useful strategy to construct one-dimensional nematic structure with three dimensional elastic properties.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.317-317
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• 2006

Dendronized linear polymers have recently come forward as new materials for nanoscale applications. These "molecular cylinders" may be modified with specific chemical makeup, rigidity, surface decoration, and backbone properties much like their spherical analogs, dendrimers. There exist three main synthetic pathways to yield dendronized polymers: (i) graft-to; (ii) graft-from; and (iii) macromonomer. We present an efficient "graft-to" approach towards dendronized microstructures utilizing click chemistry. With the capacity to manipulate their chemical composition, these dendronized structures have already found broad use in site-isolation for catalysis, nanolithography and organic light emitting diodes. These and other potential applications of these materials will be also presented.

• Journal of Welding and Joining
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• v.15 no.2
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• pp.81-88
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• 1997

The residual stresses produced by a circumferential weld between axisymmetric cylinders are one of the most important problems concerning buckling strength, fatigue strength, stress corrosion cracking in shell structures, and arc quite different from those due to a butt weld between flat plates. This paper presents experimental studies on weld cylinder models of various heat inputs and thin cylinder diameters by blind hole drilling method. As a result, it is certified that weld residual stress (axial stress and hoop stress) is larger, as heat input and shell cylinder diameter are larger, and that experimental results show good agreement with the result of preceding researchers.

• Journal of the Korean Wood Science and Technology
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• v.22 no.1
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• pp.66-71
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• 1994

To increase drying rate and reduce drying degradation, pretreatments such as prefreezing and presteaming have been widely used in wood industries. Presteaming lumbers prior to kiln drying is known positively to improve its permeability, to increase diffusion coefficient and to reduce discoloration, but negatively to increase collapse. Prefreezing lumbers prior to kiln drying is also known to reduce significantly its drying defects and its shrinkages. Thus it is no doubt that the pretreated lumbers shrink diversely from the untreated. In this study the shrinkage behaviors of the pretreated specimens are investigated by drying two tropical hardwoods (Apitong and Taun) in three different dying conditions: high temperature and slow drying rate (drying in a closed cylinder), high temperature and rapid drying rate (drying in an oven) and low temperature and slow drying rate(drying at room temperature). The prefrozen specimens show the least volumetric shrinkages in most drying conditions. The specimens dried in cylinders shrink most among all drying conditions. In general the pretreated specimens reached the 30 % moisture content faster than the untreated by about 30 %.

• Tribology and Lubricants
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• v.27 no.2
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• pp.65-70
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• 2011

The power servo cylinder for driving accurately turbine stop valve of an atomic power plant is necessary to do turn-over owing to a leakage of oil and a structure problem, especially, it of a power plant be in demand a high quality standard depends entirely on import. There are much problem that the AlBC be to used as a material of piston head in cylinder are caused by wear. Therefore, it is necessary to examine friction characteristics of it. In this study, wear test experiments was carried out with AlBC and SCM440, using reciprocating friction tester of pin on disk. This result was shown that the wear mechanism of AlBC on working condition is adhesive wear and the maximum temperature of infra redray thermal image of frictional surface show over 2 mm from contact surface of pin and disk.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.194-197
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• 2004

In the tube hydroforming process, a tube is placed into the die cavity and the ends of the tube are sealed by fixing the axial cylinder piston into the ends. Then the tube is pressurized with a hydraulic fluid and simultaneously the axial cylinders move to feed the material into the expansion zone. Therefore, the quantitative relationship between process parameters such as internal pressure and feeding amount and hydroformabillity, is hard to establish because of their high complexity and many unknown factors. In this study, the empirical and the quantitative relationship between process parameters and hydroformabillity are analyzed by fuzzy rules. Fuzzy expert system is an advanced expert system which uses fuzzy rule and approximate reasoning. Many process parameters are converted to the quantitative relationship by use of approximate reasoning of fuzzy expert system. The comparison between experimentally measured hydroformabillity from hydroforming experiments and the predicted values by fuzzy expert system shows a good agreement.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.407-410
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• 2003

The actual quality of the concrete in the structure for Irrigation may differ from that represented by the cylinders because the age, consolidation, or curing of the in-place material may not be well represented by the standard test specimens. The objective of this paper is to offer a base data of specification is the best fit the ready-mixed concrete strength to the specified, and to address this deficiency, so that the strength information of the concrete in the structure for Irrigation can be rationally accounted for in the assessment of the quality condition of this. The strength of concrete in the hydraulic structures is checked using strength of core obtained from that, and 28-day-old cylinder strength is analyzed using cylinder data of the ready-mixed concrete.

• Steel and Composite Structures
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• v.2 no.4
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• pp.259-276
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• 2002

In the present investigation the experimental and theoretical flexural and compressive behavior of short tubular steel columns filled with plain concrete and fiber-reinforced concrete (FRC) was examined. For a given length of the members, the effects of different geometry and dimensions of the transverse cross-section (square and circular) were investigated. Constituent materials were characterized through direct tensile tests on steel coupons and through compressive and split tension tests on concrete cylinders. Load-axial shortening and load-deflection curves were recorded for unfilled and composite members. Finally, simplified expressions for the calculus of the load-deflection curves based on the cross-section analysis were given and the ultimate load of short columns was predicted.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.237-240
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• 1997

The casing oscillator is a construction equipment to clamp, oscillate and push a casing for foundation work. In case that the casing oscillator is operated on the slant ground, if another construction heavy equipment is not used, it is impossible to insert the casing in ground using only casing oscillator. So in this paper, we present the new casing oscillator that need not to level the ground for work of casing insertion. This mechanism can execute 4 DOF motion by actuating 5 single - rod hydraulic cylinders. The forward kinematics analysis of the casrng oscillator by tetrahedron geometry is performed so predict workspace, direction and poison of casing oscillatoer.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.511-512
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• 2009

The purpose of this study was to propose a new steel jacketing method that does not require a grout between steel and concrete and to compare its structure performance with that of the others jacketed concrete. The proposed steel jacketing method uses external pressures on steel jackets to attach it to the surface of concrete.