• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1210-1218
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• 2011

GA (Genetic Algorithms) are efficient for searching for global optima but may have some problems such as premature convergence, convergence to local extremum and divergence. These phenomena are related to the evolutionary operators. As population diversity converges to low value, the search ability of a GA decreases and premature convergence or converging to local extremum may occur but population diversity converges to high value, then genetic algorithm may diverge. To guarantee that genetic algorithms converge to the global optima, the genetic operators should be chosen properly. In this paper, we analyze the effects of the selection operator, crossover operator, and mutation operator on convergence properties, and propose the sweeping method of mutation probability and elitist propagation rate to maintain the diversity of the GA's population for getting out of the premature convergence. Results of simulation studies verify the feasibility of using these sweeping operators to avoid premature convergence and convergence to local extrema.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.1
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• pp.147-162
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• 1997

When designing workplaces or arranging controls on panel, devices and controls should be placed within the reach of operator's arm or foot to guarantee effective performances. Most of the existing research on the reach volume were based on measurements of a few subject's arm reach, and limited to Caucasian and Chinese populations. Furthermore, reach volume considering foot or trunk motion have not been investigated. Range of human joint motion and that of two degrees of freedom motion are needed to generate reach volume analytically using the sweeping algorithm. However, range of two degrees of freedom motion has not been measured up to now. Therefore, range of two degrees of freedom motion was measured in this research, where 47 college students were participated voluntarily as subjects. The results showed that the motion of one joint can be limited by the motion of another motion, that is to say, the shoulder flexion was decreased significantly when the shoulder was adducted or abducted. Second, new approximate algorithms generating reach volumes were suggested, in which range of two degrees of freedom motion was used as input data. Depending upon the body segment included such as trunk, arm and leg, three types of reach volume were provided, in which the human body was modeled as a multilink system based on the robot kinematics and the sweeping method was employed. Reach volume generated analytically in this study showed statistically reasonable results when compared with that obtained from direct measurement.

• Proceedings of the ESK Conference
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• 1996.10a
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• pp.232-237
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• 1996

When designing workplaces or arranging controls on panel, devices and controls should be placed within the reach of operator's arm or foot to guarantee effective performances. Most of the existing research on the reach volume were based on measurements of a few subject's arm reach, and limited to Caucasian and Chineses populations, and foot reach and trunk motion have been excluded. Range of human joint motion and that of two degrees of freedom motion are needed to generate reach volume analytically using the sweeping algorithm. Therefore, in this research, range of two degrees of reedom motion was measured, in which 47 college students were participated volumtarily as subjects. Second, new approximate algorithms generating reach volumes were suggested based on the robot kinematics, in which range of two degrees of freedom motion was considered. Our analytically generated reach volume showed statistically reasonable results when compared with that obtained from direct measurement.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.579-589
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• 2011

One of the most significant UUV(Unmanned Underwater Vehicle) applications is MCM(Mine Countermeasure), which makes good use of UUV characteristics to provide covert, rapid, controlled and efficient survey of a potential minefield without risking a human operator. In this paper, a survey of the today's MCM missions where UUVs will play a role, the vehicle systems that are either under development or planned in the future are presented. And examines principal technical challenges and outline new enabling technologies. Particularly, this paper analyses current approaches to tacking these technologies and technological limitation of UUVs as a MCM platform, and research efforts to develop the technology necessary to meet the domestic MCM mission needs.