• Journal of KIISE:Computer Systems and Theory
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• v.28 no.11
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• pp.573-580
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• 2001

When tasks access shared resources in real-time systems, the unbounded priority inversion may occur. In such cases it is impossible to guarantee the schedulability of real-time tasks. Several resource access protocols have been proposed to bound the duration of priority inversion and sufficient conditions are given to guarantee the schedulability of periodic task set. In this paper, we show an improved sufficient condition for schedulability when the dynamic priority ceiling protocol is used. Our approach exploits the fact that a lower priority task can continue to execute as far as the higher priority tasks do not miss their deadlines. This permitting execution time of the higher priority tasks for a lower priority task can be excluded from the worst-case blocking time of the higher priority tasks. Since the worst-case blocking time of tasks can be reduced, the sufficient condition for schedulability of dynamic priority ceiling protocol becomes further tight.

• Journal of the Korean Regional Science Association
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• v.34 no.4
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• pp.3-18
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• 2018

These days, regional innovation draws more attention than ever as a growth engine for regional economies, and governments put a variety of efforts to establish Regional Innovation systems(RISs). In this circumstance, this study aims to analyze types of RISs and the combinations of the factors influencing innovation performance as measured by patent application. Most of previous works have depended on case-oriented or variable-oriented strategy to classify types of RISs or to analyze the effects on performance of innovation factors, having some limitations: Variable-oriented approaches fail to capture complex combinatory effects of factors, while case-oriented approaches tend to depend on subjective interpretation. This study made use of the recently proposed fs/QCA(Fuzzy-set Qualitative Comparative Analysis) to overcome the limitations of those strategies. Based on the theory of RIS, three factors for regional innovation-input, infrastructure, and network-are used to classify 16 Korean Provinces. The results show that eight types of regional innovation types are identified, and that most of the regions are classified into either IN-type, equipped with high levels of Input and Network, or F-type, with high levels of infrastructure. In addition, applying seven sub-variables of the three factors to the fussy-set combination factor analysis, we examine a combination of factors influencing patent application. The results show that regions with high levels of R&D expense, valid patent, industry-academia cooperation, IP budget, and TLO values, and low IP capital almost always have a high level of patent application. Therefore, for regional innovation, the public sector needs to provide institutional support for R & D personnel training. It is also important to for both the public and the private sectors to make efforts to stimulate IP financing.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.251-263
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• 2003

This paper presents matrix inequality conditions for Η$_2$control and Η$_2$controller design method of linear time-invariant descriptor systems with parameter uncertainties in continuous and discrete time cases, respectively. First, the necessary and sufficient condition for Η$_2$control and Η$_2$ controller design method are expressed in terms of LMI(linear matrix inequality) with no equality constraints in continuous time case. Next, the sufficient condition for Hi control and Η$_2$controller design method are proposed by matrix inequality approach in discrete time case. Based on these conditions, we develop the robust Η$_2$controller design method for parameter uncertain descriptor systems and give a numerical example in each case.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.689-694
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• 1998

본 논문에서는 상태와 제어입력에 시간지연을 가지는 이산 불확실성 시스템의 견실 H/sub ∞/ 상태궤환 제어기 설계문제를 다룬다. 동일한 제어기에 대해서, 파라미터 불확실성을 가지는 시간지연 시스템이 자승적 안정성(quadratic stability)과 폐루프 시스템의 H/sub ∞/ 노옴의 한계를 유지하면서 파라미터 불확실성이 없는 등가의 시스템으로 변형된다. 그리고 주어진 이산 불확실성 시간지연 시스템의 견실 H/sub ∞/ 상태궤환 제어기가 존재할 충분조건과 제어기 설계 알고리듬을 제시한다. 또한 변수치환과 Schur 여수(complement) 정리를 이용하면 구한 충분조건은 LMI(linear matrix inequality) 형태로 쓸 수 있다. 예제를 통하여 제시한 결과의 타당성을 보인다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.15-24
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• 2000

This paper presents an output feedback robust H$\infty$ control problem for a class of uncertain nonlinear systems, which can be represented by an fuzzy dynamic model. The nonlinear system is represented by Takagi-Sugeno fuzzy model, and the control design is carried out on the basis of the fuzzy model. Using a single quadratic Lyapunov function, the globally exponential stability and disturance 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(LMIs). Constructive algorithm for design of robust H$\infty$ controller is also developed. The resulting controller is nonlinear and automatically tuned based on fuzzy operation.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.2
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• pp.159-164
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• 2010

This paper focuses on the stability analysis and stabilization for networked control system with neutral type of time-delay. By utilizing the delay partitioning idea, new stability criteria are proposed in terms of linear matrix inequalities(LMIs). These conditions are developed based on the Lyapunov-Krasovskii functionals. Based on the derived criteria, a sufficient condition for te solvability of this problem is obtained in terms of linear matrix inequality without decomposing the original system matrices. Also, it is shown that the proposed controller design method is general for networked control systems. Finally, illustrative examples are presented to show the applicability of the proposed method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.99-108
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• 2003

This paper is concerned with the problem of designing a guaranteed cost state feedback controller for singular systems with time-varying delays. The sufficient condition for the existence of guaranteed cost controller, the controller design method, and the optimization problem to get the upper bound of guaranteed cost function are proposed by LMI(linear matrix inequality), singular value decomposition, Schur complements, and change of variables. Since the obtained sufficient conditions can be changed to LMI form, all solutions including controller gain and the upper bound of guaranteed cost function can be obtained simultaneously. Moreover, the proposed controller design method can be extended to the problem of robust guaranteed cost controller design method for singular systems with parameter uncertainties and time-varying delays. The validity of the proposed design algorithm is investigated through a numerical example.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.4
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• pp.15-20
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• 1982

Stabilization by decentralized control is an important problem in large scale systems and there has been an increasing interest in this area. The objective of this paper is to obtain the sufficient condition for an interconnected system to be stabilited by local feedback. Recently there has been many papers about this, and we further broaden the class of interconnections for which we can find a decentralized control to stabilize the overall system. The interconnection matrix may take any arbitrary time invariant values and this implies connective stability in some sense. The assumed model is mire general than most of previous ones, and as a special case, when each subsystem is given by companion form of a single inputs the result is compared with that of Ikeda and Siljak. The obtained result is illustrated by examples.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.50-54
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• 2001

미래의 해전은, 현재와 같은 추세로 살펴본다면 무기 체계의 첨단 기술이 개발이 되었을 경우, 미사일 전쟁화가 될 것으로 추정이 된다. 본 연구에서는 현재 미 해군이 차세대 구축함으로 개발하고 있는 DD2l함을 근거로 해서 전투효율과 경제성에 기초를 둔, 차세대 함정이 갖추어야 할 필요 충분 조건이 무엇인가를 고찰하기로 하였다. 하나의 임무를 갖춘 함정의 여러 척수와 다종 임무를 갖춘 한 척의 함정간의 전투 효율과 경제성에 대한 비교로 부터, 다종 임무를 갖춘 한 척이 양측면에서 우수하다는 사실이 전술과 전략 측면에 관한 각종 연구를 통해 평가되고 있다.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.478-480
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• 1989

이 논문(論文)에서는 페트리 넷트의 한 서브클래스인 활성(活性)이고 안전(安全)인 자유선택넷트의 가도달성(可到達成)에 관해 고찰했다. 활성(活性)이고 안전(安全)인 자유선택넷트의 한클래스가 가도달성(可到達成)을 가지기 위한 필요충분조건을 도출했다.