• Journal of Internet Computing and Services
• /
• v.10 no.6
• /
• pp.37-50
• /
• 2009

In this paper, we proposed a mechanism for effective cooperation in sensor network. There are a few mechanism like RBS, TPSN, FPSN for sensor network. However these are supporting synchronization among nodes without global state. Therefore, we proposed SGSM(Simple Global State Management) to maintain global state among sensor nodes. As experimental results, we confirmed loss rate is within 1% as maintaining global state with SGSM mechanism. In this paper, we defined global state in sensor network and introduced SGSM for improving timming accuracy in sensor environment.

• International Journal of Advanced Culture Technology
• /
• v.11 no.3
• /
• pp.113-121
• /
• 2023

The purpose of this study is to verify whether there is a difference in boredom between education types (offline vs. online) in the mandatory education scene, and to explore the moderator effect of meaning making activities in the relationship between education types and boredom. In this study, 197 college students were divided into offline and online groups and they participated in mandatory education. The meaning making activity was operationalized based on the meaning discovery scale. As a result of the study, the state boredom after mandatory education was significantly higher in the online group than in the offline group. However, meaning making activities did not moderate the relationship between education type and the state boredom. Through further analysis, it was found that boredom in both groups significantly decreased after the meaning making activity.

• Proceedings of the KIEE Conference
• /
• 1997.07b
• /
• pp.414-417
• /
• 1997

We propose a decentralized $H_{\infty}$ state estimation method in the multisensor state estimation problem. The proposed method bounds the maximum energy gain from unknown external disturbances to the estimation errors in the suboptimal case. And we formulate the decentralized state estimation method in the general case of different global and local models using alternative gain equation of the $H_{\infty}$ state estimator which can calculate global state estimates from the the linear combination of local state estimates. In addition, the proposed update equation between global and local Riccati solutions can reduce unnecessary calculation burden efficiently.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.5
• /
• pp.1303-1311
• /
• 1999

In order to learn in dynamic environments, reinforcement learning algorithms like Q-learning, TD(0)-learning, TD(λ)-learning have been proposed. however, most of them have a drawback of very slow learning because the reinforcement value is given when they reach their goal state. In this thesis, we have proposed a reinforcement learning method that can approximate fast to the goal state in maze environments. The proposed reinforcement learning method is separated into global learning and local learning, and then it executes learning. Global learning is a learning that uses the replacing eligibility trace method to search the goal state. In local learning, it propagates the goal state value that has been searched through global learning to neighboring sates, and then searches goal state in neighboring states. we can show through experiments that the reinforcement learning method proposed in this thesis can find out an optimal solution faster than other reinforcement learning methods like Q-learning, TD(o)learning and TD(λ)-learning.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.3
• /
• pp.187-191
• /
• 2007

We analyze the stability property of a class of nonlinear time-delay systems. We show that the state variable is bounded both below and above, and the lower and upper bounds of the state are obtained in terms of a system parameter by using the comparison lemma. We establish a time-delay independent sufficient condition for the global asymptotic stability by employing a Lyapunov-Krasovskii functional obtained from a change of the state variable. The simulation results illustrate the validity of the sufficient condition for the global asymptotic stability.

• Journal of Communications and Networks
• /
• v.9 no.4
• /
• pp.356-367
• /
• 2007

In large networks, maintaining precise global network state information is impossible. The imprecise network state information has significant impacts on Quality-of-Service(QoS) routing and path establishment. In this paper, we develop analytical models for investigating the QoS routing schemes that are designed to tolerate imprecise network state information, and study the performance of various QoS routing schemes, including randomized routing, multi-path routing, and probability based routing, using both the models and simulations. We further propose a new mechanism, called local rerouting, that improves the effectiveness of QoS path establishment in the presence of imprecise global network state information. Local rerouting is orthogonal to existing schemes for dealing with imprecise state information and can be used in conjunction with them to alleviate the impacts of the imprecise information. The results of our performance study indicate that local rerouting is robust and effective.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.6
• /
• pp.1365-1374
• /
• 1996

To alleviate the blocking inherent in 2-phase commit protocol(2PC) that is widely used to ensure the atomicity of global transactions in distributed environments, an optimistic 2PC can be used. Under the optimistic 2PC, compensation transactions are introduced to ensure the atomicity of transactions, which may result in the violation of global serializability due to the properties of compensation, transactions. In this paper, we propose several valid management protocols for global transactions to ensure the global serializability through the analysis of transaction of state transitions. To determine the execution of one global transaction, the proposed protocols check the sates of other concurrent global transactions. According to the result, execution of the global transaction may be delayed to ensure the global serializability.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2000.09a
• /
• pp.176-181
• /
• 2000

This paper briefly outline the approach we are now setting for improving the existing global ocean tidal charts in next few years. There has been notable progress in predicting global ocean tide in mid 90s to improve correction procedures for tidal signals in altimetry with more accurate tidal models (http://podaac.jpl.nasa.gov/) than existing ones. (omitted)

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.272-275
• /
• 1989

In this paper feedback linearization of valve-controlled nonlinear hydraulic velocity control system is studied. The $C^{\infty}$ nonlinear transformation T is obtained, and it is shown that this transformation is global one. Linear equivalence of nonlinear hydraulic velocity control system is obtained by this global nonlinear transformation, and linear state feedback control law is applied to this linear model. It is shown that this transformation method is to the linear approximation by simulation study..

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.2
• /
• pp.145-151
• /
• 2003

A global ultrasonic sensor system for self-localization of a mobile robot is proposed in this paper. The global ultrasonic sensor system consists of three or more ultrasonic transmitters fixed at some positions in the world coordinate and receivers in the moving coordinate of a mobile robot. In this global sensor system it is easy to get state vector of the mobile robot in the world coordinate from the distance information between each ultrasonic transmitter and receiver. An extended kalman filter algorithm is used to process the noisy ultrasonic signal and to estimate the state vector. In case of using several independent ultrasonic transmitters, it is necessary to avoid the cross talk among the ultrasonic waves and to synchronize between each ultrasonic transmitter and receiver. The small sized radio frequency modules are adopted to solve the cross talk and the synchronization problem Computer simulation and experiments are carried out to verify the effectiveness of the proposed ultrasonic sensor system.