• Journal of IKEEE
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• v.20 no.4
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• pp.378-384
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• 2016

This paper addresses the output feedback consensus problem for high-order integrators under a directed network with a communication delay. In order to solve this problem, the dynamic output feedback controller is proposed. Also, by using Lyapunov-Krasovskii functional, it is shown that the existence of the proposed consensus controller can always be guaranteed even in the presence of an arbitrarily large communication delay.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.67-69
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• 2009

This paper deals with the consensus problem for multi-agent linear dynamic systems with parameter uncertainties. All the agents are identical high-order linear systems with parameter uncertainties and their state information is exchanged through a communication network. It is shown that a consensus is achieved if there exists a feasible solution to a set of linear matrix inequalities obtained for a simultaneous stabilization problem for multiple systems. A numerical example is presented to show the effectiveness of the proposed method.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.88-90
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• 2009

This paper deals with the consensus problem for multi-agent linear dynamic systems with communication delay. All the agents are identical high-order linear systems and their state information is exchanged through a communication network with constant communication delay. It is shown that a consensus is achieved if there exists a feasible solution to a set of linear matrix inequalities obtained for a simultaneous stabilization problem for multiple systems with delay. A numerical example is presented to show the effectiveness of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.323-325
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• 2014

The consensus algorithm has a faster convergence speed as the number of cooperating neighbors increases, but the information sharing delay in the wireless network increases due to access collisions as the number of cooperating neighbors increases. Therefore, there exists a tradeoff between these two performances according to node's coverage. In this paper, we present a method of coverage control that minimizes consensus time according to network scale.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.477-482
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• 2016

This paper presents a simple approximation-based design approach for consensus tracking of heterogeneous second-order nonlinear systems under a directed network. All nonlinearities of followers are assumed to be unknown and non-identical. In the controller design procedure, graph-independent error surfaces are used and an unimplementable intermediate controller for each follower is designed at the first design step. Then, by adding and subtracting a graph-based term at the second step, the actual controller for each follower is designed by using one neural network employed to estimate a lumped and distributed nonlinearity. Therefore, the proposed local controller for each follower has a simpler structure than existing approximation-based consensus tracking controllers for multi-agent systems with unmatched nonlinearities.

• Journal of the Korean Magnetic Resonance Society
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• v.17 no.2
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• pp.76-80
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• 2013

The TCP domain is a DNA-binding domain present in plant transcription factors and has a similar structural feature to the bHTH motif of eukaryotic transcription factors. The imino proton exchange study has been performed for the DNA duplex containing the consensus DNA-binding site for the AtTCP11 transcription factor. The first two base pairs in the consensus 5'-GTGGG-3' sequence are relatively very unstable but lead to greater stabilization of the neighboring two G C base pairs. These unique dynamic features of the five base pairs in the consensus DNA sequence might play crucial roles in the effective DNA binding of the AtTCP11 protein.

• Journal of Information Processing Systems
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• v.15 no.2
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• pp.251-260
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• 2019

In order to ensure second-order multi-agent systems (MAS) realizing consensus more quickly in a limited time, a new protocol is proposed. In this new protocol, the gradient algorithm of the overall cost function is introduced in the original protocol to enhance the connection between adjacent agents and improve the moving speed of each agent in the MAS. Utilizing Lyapunov stability theory, graph theory and homogeneity theory, sufficient conditions and detailed proof for achieving a finite-time consensus of the MAS are given. Finally, MAS with three following agents and one leading agent is simulated. Moreover, the simulation results indicated that this new protocol could make the system more stable, more robust and convergence faster when compared with other protocols.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1080-1086
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• 2014

In this paper, we analyze the tradeoff performance of a consensus algorithm when it is applied to the CSMA/CA-based distributed wireless network. The consensus algorithm has a faster convergence speed as the number of cooperating neighbors increases, but the transmission delay on the wireless network increases due to access collisions as the number of cooperating neighbors increases. Therefore, there exists a tradeoff relationship between these two performances and so there exists an optimal number of cooperating neighbors that minimizes the consensus time. The result for the optimal number of neighbors according to the number of nodes that participate in the consensus shows that it is optimal for all nodes to cooperate together in the small-scale network but it is optimal to limit the number of neighbors to a fixed value in the large-scale network with nodes greater than a certain value.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.1
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• pp.34-43
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• 2000

Replicated data that is used for fault tolerant distributed system requires replica control protocol to maintain data consistency. The one of replica control protocols is quorum consensus method which accesses replicated data by getting majority approval. If site failure or communication link failure occurs and any one can't get quorum consensus, it degrades the availability of data managed by quorum consensus protocol. So it needs for ghost to replace the failed site. Because ghost is not full replica but process which has state information using meta data, it is important to simplify meta data. In order to maintain availability and simplify meta data, we propose a method to use cohort set as ghost's meta data. The proposed method makes it possible to organize meta data in 2N+logN bits and to have higher availability than quorum consensus only with cohort set and dynamic linear voting protocol. Using Markov model we calculate proposed method's availability to analyze availability and compare it with existing protocols.

• Journal of KIISE
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• v.42 no.3
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• pp.289-294
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• 2015

The consensus problem is finding a representative string, called a consensus, of a given set S of k strings. Circular strings are different from linear strings in that the last symbol precedes the first symbol. Given a set S of circular strings of length n over an alphabet ${\Sigma}$, we first present an $O({\mid}{\Sigma}{\mid}nlogn)$ time parallel algorithm for finding a consensus of S minimizing both radius and distance sum when k=3 using O(n) threads. Then we present an $O({\mid}{\Sigma}{\mid}n^2logn)$ time parallel algorithm for finding a consensus of S minimizing distance sum when k=4 using O(n) threads. Finally, we compare execution times of our algorithms implemented using CUDA with corresponding sequential algorithms.