• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.786-790
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• 2002

In this study, structural optimum design was applied to the girder of magnet over head crane. The optimization was carried out using ANSYS Code for the deadweight of girder, especially focused on the thickness of its upper, lower, side and reinforced plates. The weight could be reduced up to around 15% with constraints of its deformation, stress, natural frequency and buckling strength. The structural safety was also verified by the buckling analysis of its panel structure. It might be thought to be very useful to design the conventional structures for the weight save through the structural optimization. The objective function and restricted function were estimated by the orthogonal array, and the sensitivity analysis of design variable fur that was operated.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.263-266
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• 2004

This paper describes an intelligent piezoelectric traffic sensor which can be detected the over-weighted vehicles In motion. Based on finite element analysis for the sensor, the sensitivity was analyzed and the design was optimized. Studied parameters are the material properties of constitutional parts, the geometry of the sensor, the weight of the vehicle, and the speed of the vehicle. To verify the simulated results, we manufactured the sensor having the optimized geometry and the sensitivity was measured in the range from 0.5 to 3 ton of tensile and compressive stress. The measured results shows that the sensitivity and linearity of the sensor are closely agree with the designed values.

• Structural Engineering and Mechanics
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• v.32 no.1
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• pp.167-178
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• 2009

Initial imperfections, such as initial deflection or remaining stress, cause deterioration of buckling strength of structures. The Koiter imperfection sensitivity law has been extended to describe the mechanism of reduction for structures. The extension is twofold: (1) a number of imperfections are considered, and (2) the second order (minor) imperfections are implemented, in addition to the first order (major) imperfections considered in the Koiter law. Yet, in reality, the variation of external loads is dominant over that of imperfection. In this research, probabilistic evaluation of buckling loads against external loads subjected to probabilistic variation is conducted by extending the concept of imperfection sensitivity. A truss arch subjected to dead and live loads is considered as a numerical example. The mechanism of probabilistic variation of buckling strength of this arch is described by the proposed method, and its reliability is evaluated.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.99-103
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• 2003

An Escherichia coli strain containing the recA promoter that fused to the luxCDABE operon originating from Photorhabdus luminescens was shown to respond sensitively to genotoxic stresses. Two different recombinant bacteria, one (DPDI 657) harboring a plasmid with the recA promoter that fused to the luxCDABE operon, and the other (DPD1710) containing a chromosomally-integrated recA promoter that fused with luxCDABE, were compared and it was found that the sensitivity of 'the two strains was significantly different in terms of their bioluminescent level, response time, and the minimum detectable concentration of a chemical causing DNA damaging stress. DPDI 710, with a chromosomally-integrated single copy, generally led to lower basal luminescence levels, faster responses, increased response ratios, and an enhanced sensitivity to mutagens, when compared to DPD 1657 with a multi-copy plasmid.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.6
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• pp.287-293
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• 2005

Equations have been derived for computing electromagnetic forces by using the Continuum Design Sensitivity Analysis based on the Continuum Mechanics and the Virtual Work Principle. The resultant expressions have similar terms relating to the Korteweg-Holmholz force density, Maxwell Stress Tensor and Magnetic Charge Method but numerical implementation of the proposed scheme leads to efficient calculation and improved accuracy. In addition, the method can be easily applied to computing the magnetic force distribution as well as the global force. Results show the aforementioned advantages in comparison with the conventional methods.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.764-769
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• 1988

In this paper the failure possibility and the error possibility are used to represent reliability of a technical component and that of a human operator, respectively. The failure possibility and the error possibility are fuzzy sets on the interval [0,1]. In a man-machine system, reliability of the technical component and that of the human operator are usually affected by many factors, e.g., the environment in which a machine is operated, psychological stress of the human operator, etc. The possibility is derived from not only the failure or the error rate but also estimates of these factors. The fuzzy reasoning plays an important role in the derivation. The reliability analysis is performed by the use of the possibility obtained by the present method. Moreover this paper discusses the sensitivity analysis which evaluates what extent the change of the estimation of each factor has an influence on reliability of a man-machine system. The important factors to be ameliorated are shown through the sensitivity analysis.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.124-127
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• 2002

This paper presents a 3D shape optimization algorithm for electromagnetic devices using the design sensitivity analysis with finite element method. The structural deformation analysis based on the deformation theory of the elastic body under stress is used for mesh renewing. The design sensitivity and adjoint variable formulae are derived for the 3D nonlinear finite element method with edge element. The proposed algorithm is applied to the shape optimization of 3D electromagnet to get a uniform flux density at the air gap.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.3
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• pp.28-34
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• 2004

This paper presents the results of the structural analysis and optimal design of the ROV to be operated at 6000m depth in the ocean. This will be the first domestic deep-sea ROV operating with an AUV and a launcher equipped with robot arms and the current weight is about 3 ton. initial optimal dimension of the frame is determined based on the stress analysis using FEA code ANSYS and design sensitivity and optimization results. The current design is the initial design and there is a possibility to change the design according to the modification of material, equipments and array of structure.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1043-1049
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• 2008

Trouble by excessive axial stress in CWR layed on a bridge is frequently happen, and this problem is induced from lack of considering on the track/structure interface on preliminary design stage. In this study, the sensitivity evaluation for the major influencing parameters, that is, expansion length of span, stiffness of super structure, arrangement of bearing, and strength of sub-structure, to the axial force in CWR on a bridge is conducted. From the sensitivity study, the guideline to reduce axial force efficiently in CWR for bridge engineer was suggested. The suggested guideline may not applicable for every case, but it is helpful for preliminary design of bridge.

• Smart Structures and Systems
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• v.16 no.2
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• pp.367-382
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• 2015

This paper aims to conduct the reliability-based assessment of the welded joint in the orthotropic steel bridge deck by use of a mesh-insensitive structural stress (MISS) method, which is an effective numerical procedure to determine the reliable stress distribution adjacent to the weld toe. Both the solid element model and the shell element model are first established to investigate the sensitivity of the element size and the element type in calculating the structural stress under different loading scenarios. In order to achieve realistic condition assessment of the welded joint, the probabilistic approach based on the structural reliability theory is adopted to derive the reliability index and the failure probability by taking into account the uncertainties inherent in the material properties and load conditions. The limit state function is formulated in terms of the structural resistance of the material and the load effect which is described by the structural stress obtained by the MISS method. The reliability index is computed by use of the first-order reliability method (FORM), and compared with a target reliability index to facilitate the safety assessment. The results achieved from this study reveal that the calculation of the structural stress using the MISS method is insensitive to the element size and the element type, and the obtained structural stress results serve as a reliable basis for structural reliability analysis.