• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.110-113
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• 2004

Aluminum and CFRP tube is light-weight material representatively but collapse mechanism is different under axial loading. Aluminum tube absorbs energy by stable plastic deformation under axialloading. While CFRP(Carbon Fiber Reinforced Plastics)tube absorb synergy by unstable brittle failure but its specific strength and stiffness is higher than that of aluminum tube. In this study, for complement of detect and synergy effect by combination with the advantages of each member, the axialcollapsetests were performed for combined aluminum CFRP tubes which are composed of aluminum tubes wrapped with CFRP out side aluminum square tubes. Collapsecharacteristics were analyzed for combined square tubes which have different CFRP orientation angle and thickness. Test results were compared with that of aluminum tubes and CFRP tubes.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.729-734
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• 2000

This paper proposes virtual-magnetic system by a force-reflecting interface to drive a ultrasonic motors(USMs) To approach virtual magnet in graphic the 6 dDOF force-reflecting interfaces provides force feedback to users as if I is magnetic-force, So users can feel real magnet Effectively to display the magnetic-force we need the interface with specific characteristics such as low inertia almost zero friction and very high stiffness As an actuator for the interface the USMs have many good advantage satisfied these conditions over conventional servo motors. To estimate capability of this virtual-magnetic system we did an experiment of magnetism based on coulomb's law when Coulmb's low apply this experiment it is vey conformable to real magnet

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.23-27
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• 2007

To store hydrogen with high pressure is one of key technologies in developing FCVs (fuel cell vehicles). Especially, metal lined composite structure, which is called Type 3, is expected to effectively stand highly pressurized hydrogen since it has high specific strength and stiffness as well as excellent storage ability. However, it has many difficulties to design Type 3 vessels because of their complex geometry, fabrication process variables, etc. In this study, therefore, optimal design of Type 3 vessels was performed in consideration of such actual circumstances using genetic algorithm. Additionally, detailed finite element analysis was followed for the optimal result.

• Structural Engineering and Mechanics
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• v.45 no.4
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• pp.521-542
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• 2013

In this study a truss model is used for the geometrically nonlinear static and dynamic analysis of a thin shallow arch subject to snap-through. Thanks to the very simple geometry of a truss, the equilibrium conditions can be easily written and the global stiffness matrix can be easily updated with respect to the deformed structure, within each step of the analysis. A very coarse discretization is applied; so, in a very simple way, the high frequency modes are suppressed from the beginning and there is no need to develop a complicated reduced-order technique. Two short computer programs have been developed for the geometrically nonlinear static analysis by displacement control of a plane truss model of a structure as well as for its dynamic analysis by the step-by-step time integration algorithm of trapezoidal rule, combined with a predictor-corrector technique. These two short, fully documented computer programs are applied on the geometrically nonlinear static and dynamic analysis of a specific thin shallow arch subject to snap-through.

• Journal of the Korean Wood Science and Technology
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• v.20 no.3
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• pp.39-54
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• 1992

Hollow core wood flush doors for wardrobes, and other general openings and bathroom were designed and fabricated to investigate the factors causing the bowing of them and to find out the countermeasure for the phenomena. Balance in grain orientation, thickness, specific gravity and M.C.(%) of face panel and symmetrical construction were the essential factors to prevent the deflection of flush doors just after manufacturing. Under one-sided severe service condition, the unbalance of M.C. between opposite face panels is inevitable. So the material as thick plywood with high stiffness is considered as an alternative for the stile. UF resin mixing into PVAc emulsion is preferred for bathroom.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.501-507
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• 1997

Composite material has very excellent mechanical properties including tensile stress and specific strength. Especially impact loads may be expected in many of the engineering applications of it. The suitability of composite material for such applications is determined not only by the usual paramenters, but its impactor energy-absorbing properties. Composite material under impact load has poor mechanical behavior and so needs tailoring its structure. Genetic algorithms(GA) is probabilistic optimization technique by principle of natural genetics and natural selection and neural networks(NN) is useful for prediction operation on the basis of learned data. Therefore, This study presents optimization techniques on the basis of genetic algorithms and neural networks to minimum stiffness design of laminated composite material.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.401-405
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• 2007

Due to the low densities and high specific strength and stiffness, magnesium alloy sheets are very attractive lightweight materials for automotive and electrical products. However, the magnesium alloy sheets should be usually formed at elevated temperature because of their poor formability at room temperature. For the use of the magnesium alloy sheets for an industrial, their mechanical properties at elevated temperature and appropriate forming process conditions have to be developed. In this study, non-isothermal simulation of a square cup drawing of magnesium alloy sheets have been conducted to evaluate a proper forming process conditions such as the tool temperature, the tool shoulder radius, friction between the blank and the tools. According to this study, appropriate forming process conditions of square cup drawing at elevated temperature from magnesium alloy sheets are suggested.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.103.3-103
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• 2001

Recently Electro active polymer has been discussed in various researches as new actuators replacing the human muscles. Since they have confronted a limitation of more advanced application with traditional actuator. IPMC (Ion exchange Polymer Metal Composite) is one of candidate materials for new actuators. In this paper, we propose a new approach and design principle for the IPMC polymer actuator to conquer the weaknesses of IPMC that is intrinsic weak structural stiffness and low trust forces. In the first we performs some experimental works about how the basic specific characteristics of IPMC vary and what the optimal operating conditions are. And we have applied IPMC as active cilium for realization of annelida motion like ...

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.203-206
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• 2003

Using composite materials for the carbody of tilting train has many advantages such as manufacturing variety, specific high-strength ＆ stiffness characteristics, and long-life durability, but the strongest advantage could be the possibility of lightweight product. In the leading countries, the composite materials are used for the material fur drivers'cabs, interior/exterior equipments for railway train, and it is now developing the composite materials applied for the train carbody structure. In this paper, we conducted the evaluation of structural stability for the aluminum and composite carbody of the Korean Tilting Train express(TTX) with the service speed of 180km/h.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1616-1622
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• 2001

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.