• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.298-305
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• 2003

In this paper, we proposed a high performance lookup controller for IP packet forwarding engine of ATM based label edge routers. The lookup controller is designed to provide services such as MPLS, VPN, ELL, and RT services as well as the best effort. For high speed searching for IP addresses, we employed a TCAM based hardware search device not using traditional algorithmic approaches. We also implement lookup control functions into FPGA for fast processing of packet header and lookup control. The proposed lookup controller is designed to support differenciated services for users and to process in pipelined mechanism for performance improvement. A two-step search scheme is also applied to perform lookup for the key combined with multi-field of packet header. We found that the proposed lookup controller provides the performance of about 16M packets per second through simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2625-2632
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• 2009

Recently, a speed control method of induction motor by vector control theory is applied to highly efficient industrial field. The speed sensors attached to motor are used for detection of rotating speed. In the case using speed sensor, the installation of cable for minimization of electric noise, weaken maintenance, increase of price are demerit. Therefore the study of speed sensorless vector control theory performed activity. The design of sensorless vector controller for induction motor using tabu search is studied. The proposed sensorless vector control for Induction Motor is composed of two parts. The first part is for optimizing the speed estimation with initial PI parameters. The second part is for optimizing the speed control with initial PI parameters using tabu search. Proposed tabu search is improved by neighbor solution creation using Triangular random distribution. In order to show the usefulness of the proposed method, we apply the proposed controller to the sensorless speed control of an actual AC induction Motor System. The performance of this approach is verified through simulation and the experiment.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.133-136
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• 2004

This paper proposes a stability condition in affine Takagi-Sugeno (T-S) fuzzy systems with parametric uncertainties and then, introduces the design method of a fuzzy-model-based controller which guarantees the stability. The analysis is based on Lyapunov functions that are continuous and piecewise quadratic. The search for a piecewise quadratic Lyapunov function can be represented in terms of linear matrix inequalities (LMIs).

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1062-1065
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• 1993

Nuclear reactor operation is a human intensive task; one of the features of a problem for which fuzzy controllers present the most suitable solution. The performance of the fuzzy controllers can further be improved through tuning. In this work, application of a fuzzy controller in real-time control of a nuclear reactor is presented. The fuzzy controller is tuned on-line using direct gradient search method.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.558-562
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• 1999

In this paper, the inverter spot welding system with high efficiency via an instantaneous power control is presented. In spot welding, instantaneous power control is utilized in order to attain less spatter and high welding performance. Also we proposed a PI controller for spot welder system using Evolution Strategy(ES) with varying search space. ES with varying search space which depends on fitness values at each generation is used to tune PI control parameters

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2278-2282
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• 2003

In this paper the structure of 2-DOF controller based on artificial immune network algorithms has been suggested for nonlinear system. Up to present time, a number of structures of the 2-DOF controllers are considered as 2-DOF (2-Degrees Of Freedom) control functions. However, a general view is provided that they are the special cases of either the state feedback or the modification of PID controllers. On the other hand, the immune network system possesses a self organizing and distributed memory, also it has an adaptive function by feed back law to its external environment and allows a PDP (parallel distributed processing) network to complete patterns against the environmental situation, since antibody recognizes specific antigens which are the foreign substances that invade living creatures. Therefore, it can provide optimal solution to external environment. Simulation results by immune based 2-DOF controller reveal that immune algorithm is an effective approach to search for 2-DOF controller.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1531-1536
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• 2003

In this paper the structure of 2-DOF controller based on artificial immune network algorithms has been suggested for nonlinear system. Up to present time, a number of structures of the 2-DOF controllers are considered as 2-DOF (2-Degrees Of Freedom) control functions. However, A general view is provided that they are the special cases of either the state feedback or the modification of PID controllers. On the other hand, The immune network system possesses a self organizing and distributed memory, also it has an adaptive function by feed back law to its external environment and allows a PDP (parallel distributed processing) network to complete patterns against the environmental situation, since antibody recognizes specific antigens which are the foreign substances that invade living creatures. Therefore, it can provide optimal solution to external environment. Simulation results by immune based 2-DOF controller reveal that immune algorithm is an effective approach to search for 2-DOF controller.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.19-24
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• 2003

A new method for designing critical control systems is proposed in this paper. The controller structure is chosen as a Davison type integral controller with an observer. The proposed method consists of two steps. First, the state feedback critical control system is designed using a quadratic performance index with tunable parameters. Second, the observer gain matrix is determined by the formal LTR procedure using a Riccati equation. Consequently, the search space can be reduced considerably compared with the conventional approach. Although the proposed method sacrifices a large freedom for the choice of controller structure provided by the principle of matching, the controller structure used in this paper is not excessively complex and can be used for most applications. An illustrative design example is presented.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.1
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• pp.116-123
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• 2005

The PID controllers have been widely accepted in many industrial systems due to their robust performance in a wide range of operating conditions and their functional simplicity To implement a PID controller, its three parameters must be determined for the given plant. Conventional tuning methods are mainly based on experience and experiment and are lack of systematic procedure Recently. to overcome drawbacks of conventional tuning methods, genetic algorithms have been used, In this paper a real-coded genetic algorithm is employed to search for the optimal parameters of the PID controller for speed control of marine gas turbine engines. Simulation results show the effectiveness of the proposed scheme.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.370-372
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• 2011

기존에 연구된 사이버 물리 시스텀을 위한 동적 제어 미들웨어에서는 구성요소인 제어 장치 (Controller)가 동일한 지역망 내에 위치한 Controller를 검색하고자 할 때, 검색 하고자 하는 Controller카 자신의 상위 제어 및 관리 장치 (C&A, Controller & Administrator) 와 다른 C&A의 하위 노드인 경우, 전역의 C&A에게 모두 검색 메시지를 전송하는 심각한 문제가 존재 하였다. 본 논문에서는 이러한 비효율적인 문제를 해결하고자 같은 지역망 내의 C&A간 검색 메시지를 전달 (Forwarding) 하는 방식을 도입한다. 이를 통해 같은 지역망 내에 존재하는 Controller 검색을 위한 네트워크 트래픽을 크게 감소시킬 수 있다.