• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.3
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• pp.143-150
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• 2014

In this paper, we propose an energy efficient and delay guaranteed node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique. With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3876-3881
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• 2012

In typical master/slave teleoperation systems, a human operator generally manipulates the master to control the slave through the visual information like camera image. However, the operator may get into trouble due to the limited visual information depending on the camera positions and the delay on the visual information because of low communication bandwidth. To cope with this inherit problem in the camera-based teleoperation system, this paper presents a teleoperation system using a reconstructed graphic model instead of the camera image. The proposed teleoperation system consists of a robot control module, a master module using a force-reflective joystick, and a graphic user interface (GUI) module. The graphic user interface module provides the operator with a 3D model reconstructed using a small set of sensing data received from the remote site. The proposed teleoperation system is evaluated through a peg-in-hole assembly task.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.661-669
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• 2004

As a large number of distributed systems becoming more popular, interoperability, portability and security are becoming major concerns of modern computing. CORBA and object-oriented database which provide transparency of network and database are increasingly being used as the basis for distributed system to solve these problems. The two methods can help accomplish assurance of security by using a method-based access control technique or an attribute-based access control technique. These methods also enhance the unavailability or inefficiency caused by the delay of access process and bottleneck of the network due to the complex instance-based access control. We propose a security model on the type information based access control system that can enhance both security and availability by separating the functions delivered from CORBA and object-oriented databases. We apply the access control model specifically to enhancement of security system and also perform a test to verify the security and availability of our model.

• The Transactions of the Korea Information Processing Society
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• v.7 no.9
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• pp.2948-2957
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• 2000

A broadband access network in B- ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. To establish an end-to-end ATM connection, interworking functions between \'B5.2 interface's connection protocol and the signalling protocol, are perfonned at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. In this paper, we analyze and simulate above two interworking models in tenns of a connection setup delay and completion ratio, when call requests with eBR and VBR transfer capability arrive at the service node. We observed that the completion ratios of the two interworking models are quite closed. However the connection setup delay of parallel interworking model is improved by about 33% compared with that of the sequential interworking model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.236-239
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• 2001

This paper provides a comprehensive study of the effect of time delay on adaptive transmission methods. By adaptive we mean that the transmission of data is made adaptive according to channel conditions. That is, the modulation level at the transmitter is carefully controlled for maximizing bandwidth efficiency, on the basis of the observation of instantaneous channel characteristics. By making use of the simulator developed for the present work, a large number of channel propagation environments including the models proposed in 3GPP were submitted to the simulator and the performance with respect to both time delay and SNR is observed. The results show that the performance is very sensitive to channel delay and in some cases the performance shows irreducible BER (IBER). A large amount of delay together with a high fading rate greatly affects the performance of adaptive transmission systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.337-342
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• 2001

This paper provides a comprehensive study of the effect of time delay on adaptive transmission methods. By adaptive we mean that the transmission of data is made adaptive according to channel conditions. That is, the modulation level at the transmitter is carefully controlled for maximizing bandwidth efficiency, on the basis of the observation of instantaneous channel characteristics. By making use of the simulator developed for the present work, a large number of channel propagation environments including the models proposed in 3GPP were submitted to the simulator and the performance with respect to both time delay and SNR is observed. The results show that the performance is very sensitive to channel delay and in some cases the performance shows irreducible BER (IBER). A large amount of delay together with a high fading rate greatly affects the performance of adaptive transmission systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2081-2089
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• 1997

Accurate positioning of the throttle valve of a gasoline engine is required to implement various systems such as traction control system(TCS), cruise control system and drive-by-wire system. In this research, position control system has been developed for the throttle actuator system that uses one throttle actuation for small volume and DC servo motor for fast response. In order to drive the DC motor, PWM signal generator and PWM amplifier were built and interfaced to the motor and controller. Also, time delay control(TDC) law has been used as a basic control algorithm. A method of varying the reference model of the TDC according to the size of change in target throttle angle is proposed here. The simulation and experimental results show that both overshoot prevention and fast response are achieved by the TDC technique with this variable reference model.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.3
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• pp.324-329
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• 2005

In this paper, a robust $H\infty$ stabilization problem to a uncertain discrete-time nonlinear systems with time-delay via fuzzy static output feedback is investigated. The Takagj-Sugeno (T-S) fuzzy model is employed to represent an uncertain nonlinear system with time-delayed state. Then, the parallel distributed compensation technique is used for designing of the robust fuzzy controller. Using a single Lyapunov function, the globally asymptotic stability and disturbance attenuation of the closed-loop fuzzy control system are discussed. Sufficient conditions for the existence of robust $H\infty$ controllers are given in terms of linear matrix inequalities via similarity transform and congruence transform technique. We have shown the effectiveness and feasibility of the proposed method through the simulation.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.298-303
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• 2004

This paper deals with a stochastic stabilization of observer-based output-feedback control Takagi-Sugeno (T-S) fuzzy system with Markovian input delay. The finite Markovian process is adopted to model the input delay of the overall control system. It is assumed that the zero and hold devices are used for control input. The continuous-time T-S fuzzy system with the Markovian input delay is discretized for easy handling delay, accordingly, the discretized T-S fuzzy system is represented by a discrete-time T-S fuzzy system with jumping parameters. The stochastic stabilizability of the jump T-S fuzzy system is derived and formulated in terms of linear matrix inequalities (LMIs). The usefulness of the proposed algorithm is also certificated by simulation of 2 degree of freedom helicopter model.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.237-246
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• 2000

A broadband access network in B-ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. For call and connection control functions, DSS2 and B-ISUP signalling protocols are standardized for each of a subscriber side and a network node. B-BCC and B-ANCC protocol were proposed for VB5.2 interface. This interface allows dynamic control of ATM connections at the broadband access network. To establish an end-to-end ATM connection, interworking functions between VB5.2 interface's connection control protocol and the signalling protocol, are performed at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model recommended by ITU-T causes an overall connection setup delay by introducing the access network, because this model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. The simultaneity of the parallel interworking model minimizes the overall connection setup delay. In this paper, we analyze and simulate above two interworking models with B-BCC or B-ANCC protocol in terms of a connection setup delay and completion ratio.