• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.515-525
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• 2008

In this paper, the problem of delay-dependent stabilization for singular systems with multiple internal and external incommensurate constant point delays is investigated. The condition when a singular system subject to point delays is regular independent of time delays is given and it can be easily test with numerical or algebraic methods. Based on Lyapunov-Krasovskii functional approach and the descriptor integral-inequality lemma, a sufficient condition for delay-dependent stability is obtained. The main idea is to design multiple memoryless state feedback control laws such that the resulting closed-loop system is regular independent of time delays, impulse free, and asymptotically stable via solving a strict linear matrix inequality (LMI) problem. An explicit expression for the desired memoryless state feedback control laws is also given. Finally, a numerical example illustrates the effectiveness and the availability for the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.88-94
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• 1993

In this paper we analyze the RHLQG/FIRF optimal.contol law presented in [4,5] in order to stabilizes a stochastic linear time varying systems with modeling uncertainty. It is shown by the frequency domain analysis that the RHC is robuster than the LQ control law. Explicit LTR procedures are given to improve the robust performance of RHLQC/FIRF cotrol law. Using the mismatching function technique [8], we propose an LTR method which makes the RHLQG/FIRF controller recover the feedback properties of the R.HC law. Also we compare the LTR performance of the RHLQC/FIRF via simulation with conventional LTR methods.

• Proceedings of the IEEK Conference
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• summer
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• pp.189-192
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• 2004

This paper focuses on a TCP window-based flow control mechanism with Explicit Congestion Notification (ECN). We investigate the fundamental problem of achieving a fair window control for TCP, which cooperates with ECN. This is done by using feedback congestion pricing as a means of estimating the state of bottleneck router. The problem is solved by achieving network optimal performance, which maximize the total user utilities. We then look at the simulation of such scheme.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.32.2-32.2
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• 2018

As computational resolution of modern cosmological simulations reach ever so close to resolve individual star-forming clumps in a galaxy, a need for "resolution-appropriate" physics for a galaxy-scale simulation has never been greater. To this end, we introduce a self-consistent numerical framework that includes explicit treatments of feedback from star-forming molecular clouds and massive black holes. We perform a state-of-the-art cosmological simulation of a quasar-host galaxy at z~7.5, and demonstrate that previously undiscussed types of interplay between galactic components may hold important clues about the growth and impact of quasar-host galaxies.

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.845-858
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• 2008

In this paper, we consider a terminal, linear control system with delay, subject to unknown but bounded disturbances. For this system, we consider the problem of constructing a worst-case optimal feedback control policy, which can be corrected at fixed, intermediate time instants. The policy should guarantee that for all admissible uncertainties the system states are in prescribed neighborhoods of predefined system states, at all fixed, intermediate time instants, and in the neighborhood of a given state at a terminal time instant, and the value of the cost function is the best guaranteed value. Simple explicit rules(which can be easily implemented on-line) for constructing the optimal control policy in the original control problem are derived.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.641-642
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• 2008

In this paper, we propose a new approach for the implicit rating algorithm of finding user's intense and preference to the contents on the web. Although the explicit method dig out the user preference of specific contents based on the user's intervention, we propose the implicit method obtaining the user preference according to the user's behavioral patterns on the web implicitly and automatically without the user's intervention. The implementation results show that the proposed approach is highly valuable for supporting recommender systems in conjunction with the users lifestyle.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.6
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• pp.754-759
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• 2007

The information recommendation system offers selected documents according to information needs of dynamic users. User's needs are expressed as profiles consisting of one or more words and may be changed into some specifics through relevance feedback made by users during the recommendation process. In previous research, users have entered relevance information by taking part in explicit relevance feedbacks and learned user profiles using the positive relevance feedbacks. In this paper, we learn user profiles using not only positive relevance feedback but negative relevance feedback and reinforcement learning. To compare the proposed with previous method, we performed experiments to evaluate recommendation performance of the same topic. As a result, the former shows the improved performance than the latter does.

• Korean Journal of Cognitive Science
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• v.20 no.3
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• pp.357-381
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• 2009

Although it is known that there are personality characteristic variances in the sensitivity to environmental feedback, the trait individual difference has scarcely been explored in the context of recognition memory decision. The present study investigated this issue by examining the relationship between the feedback-based adaptive flexibility of recognition criterion positioning and personality differences in general sensitivity to non-laboratory outcomes. Experiment 1 demonstrated that veridical feedback itself had little effect on the recognition decision criterion whereas Experiment 2 demonstrated that biased feedback manipulations selectively restricted to high confidence errors, induced shifts even in the overall Old/New category criterion. Critically, individual differences in stable personality characteristic linked to reward seeking(Behavioral Activation System-BAS) and anxiety avoidance (Behavioral Inhibition System-BIS) has been shown to predict the sensitivity of subjects to this form of feedback-induced criterion learning. This data further support the idea that incremental reinforcement-based learning mechanism not often considered important during explicit recognition decisions may play a key role in criterion setting.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.41-52
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• 1992

An algorithm of transforming continuous-time state feedback gains into equivalent discrete-time feedback gains or vice versa is proposed using bilinear transformation. The proposed method is evaluated experimentally by an application control of a mobile crane system which is implemented by 16bits micro computer with A/D and D/A converters. It has been shown from the experimental result that the transformed feedback gains are virtually identical to the optimal discrete gain over range of significant sampling time. Since the transformed matrix is composed by a distinct relationship between continuous-time gain and discrete-time gain, it is noted that the proposed method can be regarded as an explicit gain transformation method compared to the other methods using series expansion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.10
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• pp.988-995
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• 2008

A consensus-based feedback linearization method is proposed to maintain a specified time-varying geometric configuration for formation flying of multiple autonomous vehicles. In this approach, there exists no explicit leader in the team, and the proposed control strategy requires only the local neighbor-to-neighbor information between vehicles. The information flow topology between the vehicles is defined by Graph Laplacian matrix, and the formation flying can be achieved by the proposed feedback linearization with consensus algorithm. The stability analysis of the proposed controller is also performed via eigenvalue analysis for the closed-looop system. Numerical simulation is performed for rotary-wing type micro aerial vehicles to validate the performance of the proposed controller.