• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.81-85
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• 2005

In this paper, the structural design optimization of a wafer grinding machine using a multi-step optimization with genetic algorithm is presented. The design problem, in this study, is to find out the optimum configuration and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously under several design constraints. The first design step is shape optimization, in which the best structural configuration is found by getting rid of structural members that have no contributions to the design objectives from the given initial design configuration. The second and third steps are sizing optimization. The second design step gives a set of good design solutions having higher fitness for lightweight and minimum static compliance. Finally the best solution, which has minimum dynamic compliance and weight, is extracted among those good solution set. The proposed design optimization method was successfully applied to the structural design optimization of a high precision wafer grinding machine. After optimization, both static and dynamic compliances are reduced more than $92\%\;and\;93\%$ compared with the initial design, which was designed empirically by experienced engineers. Moreover the weight of the optimized structure are also slightly reduced than before.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.18-25
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• 2018

The head frame structure of a machine tool for aircraft parts, which requires machining precision and machining of difficult-to-cut materials is required to be light-weighted for precision high-speed machining and to minimize possible deformation by cutting force. To achieve high stiffness and for light-weight structure optimization design, a preliminary model was designed based on finite element analysis. The topology optimization design of light-weight, high stiffness, and low vibration frame structure were performed by minimizing compliance. As a result, the frame weight decreased by 17.3%, the maximum deflection was less than 0.007 mm, and the natural frequency increased by 30.6%. The static stiffness was increased in each axis direction and the dynamic stiffness exhibited contrary results according to the axis. Optimized structure with the high stiffness of low vibration in topology optimization design was confirmed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.688-696
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• 1995

Cemented carbides, best known for their superior mechanical properties such as high strength, high hardness and high wear resistance, have a wide range of industrial applications including metal working tools, mining tools, and wear resistance components. The cobalt has been used as a binder in the WC-based hard composites due to its outstanding wetting and adhesion characteristics even though its expensiveness. Therefore many studies attempted to find a better substitute for cobalt as binder to decrease production costs. This investigation is a pre-step to study dynamic fracture characteristic evaluation of a WC-Co hardmetal were evaluated by using the instrumented Charpy impact testing procedures. It was found that the dynamic characteristics of used strain amplifier were very important experimental factors to extract valid dynamic fracturing data in WC-Co specimens. It was suggested by showing some experimental examples that when we wished to evaluate dynamic fracture toughness for cemented carbide composites by using the instrumented Charpy impact testing procedure, a careful attention must be given to obtain valid results.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.159-166
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• 1998

The problem of interface crack in the bonded structures has received a great deal of attention in recent years. In this paper the aluminum bonded single lap-joint containing the interface edge crack is investigated. The tensile load and the average shear stress of the adhesive joints which have different crack length are obtained from the static tensile tests. The critical value of crack length to provoke the interface fracture is determined to a/L=0.4, where a is the interface crack length and L is the adhesive lap-length. The fracture mechanical parameters are introduced to confirm the existence of the critical crack length. The compliance and the stress intensity factors are calculated using the displacement and the stress near the interface crack tip by the boundary element method. These numerical results support the experimental results that the critical value of a/L is 0.4. It is known that the compliance and the stress intensity factors are the efficient parameters to estimate the bonded single lap-joint containing the interface edge crack.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.47-53
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• 2019

This paper is analyzed of the characteristics of development operations and development security operations of the software and product, and the use analysis tools from a software code perspective. Also, it is emphasized the importance of human factors and the need to strengthen them, when considering security design rules. In this paper, we consider a secure process for managing change, focusing on fast and accurate decision-making in terms of procedural factors, when considering development security operations. In addition, the paper discussed the need for maturity model analysis in relation to the development security operating characteristics, and analyzed the meaning of the analysis elements through detailed procedures for the strength and integration elements of the dynamic and static elements accordingly. The paper also analyzed factors such as scanning activity and code analysis for threat modeling and compliance and control.