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Modified Ant Colony Optimization for Topology Optimization of Geometrically Nonlinear Structures
유광선,한석영 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Standard Ant Colony Optimization (ACO) algorithm cannot provide an optimal topology for geometrically nonlinear structuralproblems. The reason is that the tangential stiffness matrix of low-density elements may become zero or negative, which leads toserious numerical instability problems, or the standard ACO algorithm cannot search the really efficient elements because of improperelement search method. A modified ant colony optimization (MACO) algorithm is suggested to improve computational efficiency andsuitability of standard ACO algorithm in topology optimization for these problems. A continuous variable, called the “ElementContribution Significance (ECS),” is introduced, which serves to replace the positions of ants in the standard ACO algorithm, andassess the importance of each element in the optimization process. The optimized topologies based on MACO algorithm are comparedto those of the other topology methods. From the comparison, it is verified that MACO algorithm can successfully be applied totopology optimization for geometrically nonlinear structures, as well as provide stable and robust topologies.
유광선,이승욱,우창호,이준찬,장은진,황재민,김진규,차원호,김동국,구본주,박성옥,최두영,최정림 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.3
The Ionospheric Anomaly Monitoring by Magnetometer And Plasma-probe (IAMMAP) is one of the scientific instruments for the Compact Advanced Satellite 500-3 (CAS 500-3) which is planned to be launched by Korean Space Launch Vehicle in 2024. The main scientific objective of IAMMAP is to understand the complicated correlation between the equatorial electro-jet (EEJ) and the equatorial ionization anomaly (EIA) which play important roles in the dynamics of the ionospheric plasma in the dayside equator region. IAMMAP consists of an impedance probe (IP) for precise plasma measurement and magnetometers for EEJ current estimation. The designated sun-synchronous orbit along the quasi-meridional plane makes the instrument suitable for studying the EIA and EEJ. The newly-devised IP is expected to obtain the electron density of the ionosphere with unprecedented precision by measuring the upper-hybrid frequency (fUHR) of the ionospheric plasma, which is not affected by the satellite geometry, the spacecraft potential, or contamination unlike conventional Langmuir probes. A set of temperaturetolerant precision fluxgate magnetometers, called Adaptive In-phase MAGnetometer, is employed also for studying the complicated current system in the ionosphere and magnetosphere, which is particularly related with the EEJ caused by the potential difference along the zonal direction.