• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.170-175
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• 1998

Transporting a large table using multiple robotic agents requires at least two group behaviors of homing and herding which are to bo coordinated in a proper sequence. Existing GP methods for multi-agent learning are not practical enough to find an optimal solution in this domain. To evolve this kind of complex cooperative behavior we use a novel method called fitness switching. This method maintains a pool of basis fitness functions each of which corresponds to a primitive group behavior. The basis functions are then progressively combined into more complex fitness functions to co-evolve more complex behavior. The performance of the presented method is compared with that of two conventional methods. Experimental results show that coevolutionary fitness switching provides an effective mechanism for evolving complex emergent behavior which may not be solved by simple genetic programming.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3591-3596
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• 2013

The enantioselective aza-Morita Baylis Hillman reaction of nitroalkene and N-tosylimine catalyzed by thiourea-tertiary amine has been investigated using density functional theory. Enantioselectivity is dominated by the cooperative effect of non-covalent and weak covalent interactions imposed by different units of catalyst. As Lewis base, the tertiary amine unit activates nitroalkene via weak covalent bond. The weak covalent interaction orients the reaction in a major path with smaller variations of this bond. The aromatic ring unit activates N-tosylimine via ${\pi}-{\pi}$ stacking. The non-covalent interaction selects the major path with smaller changes of the efficient packing areas. Thiourea unit donates more compact H-bonded network for species of the major path. The calculated ee value in xylene solution phase (97.6%) is much higher than that in N,N-Dimethylformamide (27.2%). Our conclusion is also supported by NBO analysis.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.292-297
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• 1999

Evolving in artificial agent is an extremely difficult problem, but on the other hand, a challenging task. At present the studies mainly centered on single agent learning problem. In our case, we use simulated soccer to investigate multi-agent cooperative learning. Consider the fundamental differences in learning mechanism, existing reinforcement learning algorithms can be roughly classified into two types-that based on evaluation functions and that of searching policy space directly. Genetic Programming developed from Genetic Algorithms is one of the most well known approaches belonging to the latter. In this paper, we give detailed algorithm description as well as data construction that are necessary for learning single agent strategies at first. In following step moreover, we will extend developed methods into multiple robot domains. game. We investigate and contrast two different methods-simple team learning and sub-group loaming and conclude the paper with some experimental results.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1087-1090
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• 2005

최근에 웹 기반의 공동 작업에 대한 연구가 활발히 진행되고 있으며, 웹 표준 언어인 XML 데이터에 대한 접근 제어 및 관리에 대한 필요성이 점차 중요시되고 있다. 이에 접근 제어 표준인 XACML이 제안되었지만, 공동 작업에 대한 정의가 없는 문제가 있다. 본 논문은 이러한 문제를 해결하기 위하여 공동 작업에 관한 기능을 기존의 XACML 스키마에 추가하여 확장하였으며, 이를 통해 기존의 공동 작업을 위한 XML 데이터에서 원하지 않는 권한 모두를 위임하는 경우를 방지하고, 권한의 오 남용을 줄 일 수 있게 되었다. 또한 본 논문에서는 이러한 공동 작업을 관리하기 위한 접근 권한 메커니즘을 설계하고 구현한다.

• Smart Structures and Systems
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• v.7 no.3
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• pp.199-211
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• 2011

Using computational modeling, we design a pair of biomimetic microcapsules that exploit chemical mechanisms to communicate and alter their local environment. As a result, these synthetic objects can undergo autonomous, directed motion. In the simulations, signaling microcapsules release "agonist" particles, while target microcapsules release "antagonist" particles and the permeabilities of both capsule types depend on the local particle concentration in the surrounding solution. Additionally, the released nanoscopic particles can bind to the underlying substrate and thereby create adhesion gradients that propel the microcapsules to move. Hydrodynamic interactions and the feedback mechanism provided by the dissolved particles are both necessary to achieve the cooperative behavior exhibited by these microcapsules. Our model provides a platform for integrating both the spatial and temporal behavior of assemblies of "artificial cells", and allows us to design a rich variety of structures capable of exhibiting complex dynamics. Due to the cell-like attributes of polymeric microcapsules and polymersomes, material systems are available for realizing our predictions.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.918-925
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• 2006

Medical robotics and computer aided surgery in general, and robotic telesurgery in particular, are promising applications of robotics. In this paper, we shows a novel single-master (PHANTOM based single-master multi-slave telerobotic system) multi-slave system using two parallel mechanism micromanipulators as a slave device. After a general introduction to the systems structure and configuration of telerobotic system, a manipulation control strategy to build the system that human and both manipulators perform the cooperative manipulation, is introduced, followed by its kinematic analysis, mapping method, and experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.188-202
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• 2004

This research was designed to investigate biomechanical aspects of the evolution based on the hypothesis of dynamic cooperative interactions between the locomotion pattern and the body shape in the evolution of human bipedal walking The musculoskeletal model used in the computer simulation consisted of 12 rigid segments and 26 muscles. The nervous system was represented by 18 rhythmic pattern generators. The genetic algorithm was employed based on the natural selection theory to represent the evolutionary mechanism. Evolutionary strategy was assumed to minimize the cost function that is weighted sum of the energy consumption, the muscular fatigue and the load on the skeletal system. The simulation results showed that repeated manipulations of the genetic algorithm resulted in the change of body shape and locomotion pattern from those of chimpanzee to those of human. It was suggested that improving locomotive efficiency and the load on the musculoskeletal system are feasible factors driving the evolution of the human body shape and the bipedal locomotion pattern. The hypothetical evolution method employed in this study can be a new powerful tool for investigation of the evolution process.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.392-400
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• 2008

This paper proposes a novel optimization algorithm inspired by bacteria behavior patterns for foraging. Most bacteria can trace attractant chemical molecules for foraging. This tracing capability of bacteria called chemotaxis might be optimized for foraging because it has been evolved for few millenniums. From this observation, we developed a new optimization algorithm based on the chemotaxis of bacteria in this paper. We first define behavior and decision rules based on the behavior patterns of bacteria and then devise an optimization algorithm with these behavior and decision rules. Generally bacteria have a quorum sensing mechanism that makes it possible to effectively forage, but we leave its implementation as a further work for simplicity. Thereby, we call our algorithm a simple bacteria cooperative optimization (BCO) algorithm. Our simple BCO is tested with four function optimization problems on various' parameters of the algorithm. It was found from experiments that the simple BCO can be a good framework for optimization.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.30.1-30
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• 2001

This paper describes a new cooperative strategy for two wheelchairs to climb a step. These two wheelchairrobots are connected with a simple linkage mechanism between the rear of one wheelchair and the front of another. Two wheelchair robots climb a step one after the other. In this research, We did not use a method by Which a robot lifts up and supports its weight using any special actuator but a method of handling the robot's moment of rotation by the force of the link which come from the assisting robot. This method is especially influenced by the height of the two robot's link positions. So we study this method from the viewpoint of changing the two-link positions....

• Bulletin of the Korean Chemical Society
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• v.4 no.2
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• pp.68-72
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• 1983

The $pK_{a}$ of $-NH_{3}^{+}$ group of chitosan in water was 6.2, while that of D-glucosamine-HCl, monomer of chitosan, was found to be 7.8. The difference of $pK_{a}$ values between chitosan and D-glucosamine was attributed to the strong electrostatic interaction between $-NH_{3}^{+}$ groups in chitosan. The apparent binding constant of $Cu^{2+}$ to D-glucosamine was estimated to be $1{\times}10^{4}$. For chitosan, no significant binding of $Cu^{2+}$ to the polymer was observed when pH < 5, but strong cooperative binding was observed near pH 5.1. The mechanism of such cooperativity was proposcd. Chitosan in solution exhibited typical polyelectrolytic behaviors: viscosity increases with increased amount of charged group, and decreases with addition of salt. The concentration dependence of viscosity was measured, and the Huggins parameters and intrinsic viscosity were calculated at various ionic strength. The results were interpreted in terms of molecular properties of the chitosan molecule.