• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.915-927
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• 2008

Networked control systems(NCSs) have gained increasing attention in recent years due to their advantages and potential applications. The network Quality-of-Service(QoS) in NCSs always fluctuates due to changes of the traffic load and available network resources. To handle the network QoS variations problem, this paper presents an intelligent scheduling control method for NCSs, where the sampling period and the control parameters are simultaneously scheduled to compensate the effect of QoS variation on NCSs performance. For NCSs with network-induced delays and packet dropouts, a discrete-time switch model is proposed. By defining a sampling-period-dependent Lyapunov function and a common quadratic Lyapunov function, the stability conditions are derived for NCSs in terms of linear matrix inequalities(LMIs). Based on the obtained stability conditions, the corresponding controller design problem is solved and the performance optimization problem is also investigated. Simulation results are given to demonstrate the effectiveness of the proposed approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.396-413
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• 2017

Dynamically checking the integrity of software at run-time is always a hot and difficult spot for trusted computing. Control-flow integrity is a basic and important safety property of software integrity. Many classic and emerging security attacks who introduce illegal control-flow to applications can cause unpredictable behaviors of computer-based systems. In this paper, we present a software-based approach to checking violation of control flow integrity at run-time. This paper proposes a high-performance and low-overhead software control flow checking solution, control flow checking at virtual edges (CFCVE). CFCVE assigns a unique signature to each basic block and then inserts a virtual vertex into each edge at compile time. This together with insertion of signature updating instructions and checking instructions into corresponding vertexes and virtual vertexes. Control flow faults can be detected by comparing the run-time signature with the saved one at compile time. Our experimental results show that CFCVE incurs only 10.61% performance overhead on average for several C benchmark programs and the average undetected error rate is only 9.29%. Compared with previous techniques, CFCVE has the characteristics of both high fault coverage and low memory and performance overhead.

• Journal of Biosystems Engineering
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• 제13권4호
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• pp.46-55
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• 1988

The objective of this study was to develop a computer measurement and control system which enable it possible to manage the natural air rough rice drying and storage properly and safely. The following contents of work were taken in this study in order to fulfill the above goal: 1) Design and construction of measurement system which can measure the rough rice drying conditions automatically and transfer them to computer system for data processing. 2) Development of a management software which can determine the need of fan operation by the analysis of drying and/or storage conditions. 3) Design and construction of a control system which deliver the computer decision of fan operation and make it on and off. 4) Technical and economical analysis of the computer measurement and control system development by the comparison experiments of the computer management and of the manual.

• 한국산업융합학회 논문집
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• 제7권2호
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• pp.207-213
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• 2004

This paper describes the development of Behind-Tape-Reader (BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-AT cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and that between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• 한국지능시스템학회:학술대회논문집
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• 한국지능시스템학회 2008년도 춘계학술대회 학술발표회 논문집
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• pp.233-236
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• 2008

Recently, the development and application of unmaned robots are increasing in various fields including surveillance and reconnaissance, planet exploration and disaster relief. Unmaned robots are usually controlled from distance using radio communications but they should be equipped with autonomous travelling function to cope with unexpected terrains and obstacles. This means that unmanned robots should be able to evaluate terrain's characteristics quantitatively using mounted sensors so as to traverse harsh natural terrains autonomously. For this purpose, this paper presents an algorithm for extracting terrain information from elevation maps as an early step of traversability analysis. Slope and roughness information are extracted from a world terrain map based on least squares method and fractal theory, respectively. The effectiveness of the proposed algorithm is verified on both fractal and real terrain maps.

• 정보처리학회논문지A
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• 제15A권6호
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• pp.309-316
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• 2008

대공방어용 임무지향 교전통제 컴퓨터는 장시간 동안 임무의 중단없이 방어 임무를 수행하여야 하며, 복잡한 내장형 임무 소프트웨어를 탑재하는 컴퓨터에는 대공방어 임무의 특성상 확실성과 안정성 및 신뢰성을 보장하여야 한다. 구현된 임무지향 교전통제 컴퓨터에서 임무수행의 확실성과 안정성은 4 장의 프로세서로 구성되는 분산 컴퓨터 아키텍처에 의해 보장되며, 신뢰도는 분산 구조의 컴퓨터에 저비용의 능동 예비 이중화(ASR) 고장감내 기법을 적용하여 보장되도록 하였다. 소프트웨어적인 능동 예비 이중화 고장감내 기법은 높은 신뢰도와 신속한 고장복구 성능을 가지는 교전통제 컴퓨터를 저비용으로 구현하므로 대공방어용 컴퓨터에 매우 적합한 기법이다. 본 논문은 능동 예비 이중화 고장감내 기법의 메커니즘과 성능분석에 대해 기술하고, 교전통제 컴퓨터에 ASR 기법과 하드웨어적인 DMR 및 TMR 고장감내 기법을 적용한 경우의 MTBF, 신뢰도, 가용성 및 저비용성을 비교분석하였다. ASR 기법은 72 시간의 임무 시간에 대하여 TMR과 유사한 임무 신뢰도를 제공하며, 저비용의 구현이 가능하므로 교전통제 임무지향 컴퓨터의 고장감내 기법으로 최적인 것으로 분석되었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1295-1299
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• 2003

The Mass Flow Controller(MFC) has become crucial in semiconductor manufacturing equipments. It is an important element because the quality and the yield of a semiconductor process are decided by the accurate flow control of gas. Therefore, the demand for the high speed and the highly accurate control of MFCs has been requested. It is hard to find an article of the control algorithm applied to MFCs. But, it is known that commercially available MFCs have PID control algorithms. Particularly, when the system detects the flow by way of heat transfer, MFC control problem contains the time delay and the nonlinearity. In this presentation, MFC control algorithm with the superior performance to the conventional PID algorithm is discussed and the superiority is demonstrated through the experiment. Fuzzy controller was utilized in order to compensate the nonlinearity and the time delay, and the performance is compared with that of a product currently available in the market. The control system, in this presentation, consists of a personal computer, the data acquisition board and the control algorithm carried out by LabWindows/CVI program on the PC. In addition, the method of estimating an actual flow from sensor output containing the time delay and the nonlinearity is presented. In conclusion, according to the result of the experiment, the proposed algorithm shows better accuracy and is faster than the conventional controller.

• International Journal of Control, Automation, and Systems
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• 제3권4호
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• pp.648-648
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• 2005

• 대한기계학회논문집A
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• 제23권6호
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• pp.922-930
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• 1999

This paper describes a new 14-CPU real-time distributed automatic gauge control (AGC) system for POSCO's No. 2 Hot Strip Mill at Pohang Works. The new AGC system has adopted gaugemeter AGC, Monitor AGC, and roll gap disturbance compensators. The computer system for the new AGC system has been developed based on VMEbus computer systems and a commercial real-time operating system. A VMEbus computer system is also used for the position servo control of hydraulic cylinders. All the application programs and input/output signals have been reasonably distributed over the control computer systems for the maximum reliability and effectiveness of the system. The new AGC system has been successfully used for the No. 2 Hot Strip Mill.

• 전기의세계
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• 제25권6호
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• pp.81-88
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• 1976

The present voltage-reactive power control aims at an overall coordination of reactive power sources and voltage regulation devices to keep the bus voltages within their allowable bounds on one hand and to reduce the transmission losses on the other. This paper presents an efficient computer control scheme for the real-time control of system voltage and reactive power on the basis of a simplified linear equation by using the system characteristic constant. Computational algorithm is used for the minimization of bus voltage deviation in the first phase of optimization and for the reduction of transmission losses under the constraint of vlotage settling condition in the second phase. The numerical example for sample practical system is also given. The present study on the computer control scheme will contribute to the automation of power system operation in the near future.