• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.635-641
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• 2008

In this paper, we used a laser range finder (LRF) to detect both the static and dynamic obstacles for the safe navigation of a mobile robot. LRF sensor measurements containing the information of obstacle's geometry are first processed to extract the characteristic points of the obstacle in the sensor field of view. Then the dynamic states of the characteristic points are approximated using kinematic model, which are tracked by associating the measurements with Probability Data Association Filter. Finally, the collision avoidance algorithm is developed by using fuzzy decision making algorithm depending on the states of the obstacles tracked by the proposed obstacle tracking algorithm. The performance of the proposed algorithm is evaluated through experiments with the experimental mobile robot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3171-3191
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• 2016

Due to growing demand on wireless data traffic, a large number of different types of base stations (BSs) have been installed. However, space-time dependent wireless data traffic densities can result in a significant number of idle BSs, which implies the waste of power resources. To deal with this problem, we propose an active state control algorithm based on semi-Markov decision process (SMDP) for a heterogeneous network. A MDP in discrete time domain is formulated from continuous domain with some approximation. Suboptimal on-line learning algorithm with a random policy is proposed to solve the problem. We explicitly include coverage constraint so that active cells can provide the same signal to noise ratio (SNR) coverage with a targeted outage rate. Simulation results verify that the proposed algorithm properly controls the active state depending on traffic densities without increasing the number of handovers excessively while providing average user perceived rate (UPR) in a more power efficient way than a conventional algorithm.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.03a
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• pp.127-130
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• 1998

In this paper, we propose a method of cooperative control(T-cell modeling) and selection of group behavior strategy(B-cell modeling) based on immune system in distributed autonomous robotic system(DARS). Immune system is living body's self-protection and self-maintenance system. Thus these features can be applied to decision making of optimal swarm behavior in dynamically changing environment. For the purpose of applying immune system to DARS, a robot is regarded as a B cell, each environmental condition as an antigen, a behavior strategy as an antibody and control parameter as a T-call respectively. The executing process of proposed method is as follows. When the environmental condition changes, a robot selects an appropriate behavior strategy. And its behavior strategy is stimulated and suppressed by other robot using communication. Finally much stimulated strategy is adopted as a swarm behavior strategy. This control scheme is based of clonal selection and idiotopic network hypothesis. And it is used for decision making of optimal swarm strategy. By T-cell modeling, adaptation ability of robot is enhanced in dynamic environments.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.684-686
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• 2000

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia. and high efficiency. However position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle for speed control. The proposed system consists of position decision. phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through the experiment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.39-51
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• 1987

This paper deals with the case analysis of second order processes under sampled-data. Proportional Integral-Derivative(PID) control, and development of Decision Support Systems(DSS) for such processes. In this paper three techniques were described for identifying the dynamics of closed loop stable processes. The first, called pulse testing is a frequency-domain method, which yields the frequency response diagram of an open loop process. The second is a time-domain method which yields the gain and time constants of the process model. The third technique is based on step response and gives the parameters of PID controllers. The development of DSS design programs consisting of above three techniques will provide very powerful tools in the microcomputer based process control.

• Water for future
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• v.19 no.4
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• pp.339-346
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• 1986

A real-time single reservoir operation model using the Min-max Dynamic Programming for the flood control of Soyanggang Dam and Choongju Dam is developed. The objective function is to minimize the maximum release from each dam and the constraints are those from ther reservoir and channel characteristics. Control and utilization efficiencies are used to measure the performance of the reservoir operation method (ROM). In comparison with those of simulation models(such as the Rigid ROM, the Technical ROM and the Linear Decision Rule), the efficiencies of the optimization model are superior for all return periods.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1350-1353
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• 1993

A fuzzy control system typically requires“tuning,”or adjuctment of the parameters defining its linguistic variables. Automating this process amounts to applying a second“metacontrol”layer to drive the controller and plant to desired performance levels. Current methods of automated tuning rely on a single crisp numeric functional to evaluate control system performance. A generalization of Box's complex algorithm allows more realistic tuning based on lexicographic aggregation of multiple ordinal scales of performance, such as effectiveness and efficiency. The method is presented and illustrated using a simple inverted pendulum control system.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1301-1303
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• 1996

A new automatic frequency control(AFC) tracking algorithm, which we call a rotational decision directed AFC(RDDAFC) is proposed for QPSK demodulation at the digital direct broadcasting satellite(DBS). In order to prevent the presence of the residual phase difference between symbols received at k and k-l by the CPAFC[1] as well as the AFC based on $tan^{-1}$ circuit[2], the RDDAFC rotates the decision boundary for the kth received symbol by the frequency detector output of the (k-1)th received symbol before passing through the cross product discriminator. Test results show that the total pull-in time of the RDDAFC and PLL was 0.13msec under a carrier frequency offset of 2.4MHz when S/N equals 2dB.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.240-245
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• 2012

A 160 MW drum-type boiler-turbine system is developed in the present research through a multi-multivariable dynamic matrix control (DMC) scheme and a multi-multivariable model approach. A novel intelligence-based decision mechanism (IBDM) is realized to support both model approach and control scheme. In such case, the responsibility of the proposed IBDM is to identify the best multivariable model of the system and the corresponding multivariable DMC scheme to cope with the system at each instant of time in an appropriate manner.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.4
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• pp.482-493
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• 2012

Logistics security has been enhanced to control cargo containers effectively and safely in global logistics. In response to the change, This study describes the system now being developed that tracks container position, watches cargo security status and gets informations of surrounding until the cargos arrived at its destination. We examine completion and satisfaction of the product for prospective users. For this, considering earlier studies about customer trust, satisfaction, service quality and purchase decision, we analyse an effect among the variables empirically. As a result, when the program is released, we examine customers' satisfaction and purchase decision for the informations to be offered from the program.