• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.807-810
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• 2003

EMFG(Extended Mark Flow Graph)는 이산시스템을 개념설계하거나 상세설계할 수 있는 좋은 도구이다. 시스템을 설계함에 있어서 마크흐름을 분석하는 것은 시스템의 성능향상과 직결되므로 상당히 중요한 작업이다. 본 논문에서는 EMFG의 각 박스들간의 상태변화를 박스추이가중행렬을 통하여 확인, 분석하는 기법을 제안하고자 한다. EMFG로 설계한 시스템의 상태변화를 쉽게 분석함으로써 시스템의 설계 및 분석이 쉬워지므로 자동화된 시스템 개발시 유용하게 사용될 것으로 기대된다.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1173-1176
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• 1999

전력계통에서 발생하는 저주파 동요에 대해서 가장 효과적인 제동력 향상방안으로 알려진 PSS의 최적 설치지점을 결정하기 위하여 NSE(Normalizing Speed Eigenvectors), SPF(Speed Participation Factors), TFR(Transfer Function Residues) 및 주파수 응답법을 각각 비교분석 하였다. 분석결과 SPF는 제어/입력 행렬을 포함하지 않는 상태행렬만을 고려하기 때문에 PSS의 제어특성을 반영하지 못하는 단점이 있었으며 TFR은 여자기 이득에 민감하여 최적위치 선정에 있어서 문제점을 보였다. 본 연구에서는 SPF법을 이용하여 PSS 설치 후보지를 선정하고 이들 후보지에 대해서 TFR법과 주파수 응답법으로 최적의 발전기를 결정하도록 하였으며 PSS를 설치하여 그 효과를 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.5
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• pp.8-12
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• 2008

In this paper, the robust state observer for nonlinear systems with unknown disturbance is proposed. The proposed method has an advantage in that it can reduce the effect of disturbance on estimation error of observer up to a specified level. Therefore, our design a roach can deal with a larger class of uncertain nonlinear system than the existing methods. The sufficient conditions on the existence of robust observer are characterized by well grown linear matrix inequality. Finally, an illustrative example is given to verify the proposed design scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2129-2139
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• 2009

In this paper, we diagnose the fault in the CA analyzer by setting up the initial value such that the final test signature is a constant regardless of the circuit being tested. This method makes the CA test procedure short and clear. In addition, we detect the fault of the faulty input sequence by using the inverse matrix of the CA state transition matrix.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.574-580
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• 2015

The stability condition of linear discrete interval systems with a time-varying delay time is considered. The considered system has interval system matrices for both non-delayed and delayed states with time-varying delay time within given interval values. The proposed condition is derived by using Lyapunov stability theory and expressed by very simple inequality. Compared to previous results, the stability issue on the interval systems is expanded to time-varying delay. Furthermore, the new condition can imply the existing results on the time-invariant case and show the relation between interval time-varying delay time and stability of the system. The proposed condition can be applied to find the stability bound of the discrete interval system. Some numerical examples are given to show the effectiveness of the new condition and comparisons with the previously reported results are also presented.

• Journal of the Korea Society for Simulation
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• v.33 no.1
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• pp.19-26
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• 2024

The phase-type, PH, distribution is defined as the time to absorption into a terminal state in a continuous-time Markov chain. As the PH distribution includes family of exponential distributions, it has been widely used in stochastic models. Since the PH distribution is represented and generated by an initial probability vector and a generator matrix which is called the Markovian representation, we need to find a vector and a matrix that are consistent with given set of moments if we want simulate a PH distribution. In this paper, we propose an approach to simulate a PH distribution based on distribution function which can be obtained directly from moments. For the simulation of PH distribution of order 2, closed-form formula and streamlined procedures are given based on the Jordan decomposition and the minimal Laplace transform which is computationally more efficient than the moment matching methods for the Markovian representation. Our approach can be used more effectively than the Markovian representation in generating higher order PH distribution in queueing network simulation.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1428-1432
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• 2008

상수관망이 노후화됨에 따라 파괴나 누수와 같은 운영상의 문제가 빈번하게 발생한다. 따라서 상수관망의 상태를 보다 정확히 파악하여 운영할 경우 안정적인 상수관망의 운영이 가능할 것이며 관파괴와 같은 돌발적인 사태의 피해를 최소화 할 수 있을 것이다. 그러나 상수관망의 실시간 모니터링 센서중 대표적인 online 압력계를 모든 지점에 설치할 경우 과다한 초기투자 비용이 소요되며 시스템의 유지관리 측면에서도 적절하지 않다. 따라서 본 연구에서는 상수관망의 실시간 모니터링을 위한 적정한 규모의 online 압력계 설치위치의 결정 방법을 제안하였다. 제안된 방법은 영향행렬지수(Effect Index Matrix)를 기반으로 하며 영향행렬지수내 column search를 수행하여 online 압력계의 위치를 선정한다. 제안된 방법을 미국의 Cherry Hill 상수관망에 적용하여 적용성을 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.7-14
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• 2000

This paper describes the synthesis of robust decentralized controllers for uncertain large-scale discrete-time systems with time-delays in subsystem interconnections. Based on the Lyapunov method, a sufficient condition for robust stability, is derived in terms of a linear matrix inequality (LMI). The solutions of the LMI can be easily obtained using various efficient convex optimization techniques. A numerical example is given to illustrate the proposed method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.16-22
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• 2001

In this study for reduction degree of freedom of dynamic model, a mixed method to combined finite element method and transfer matrix method is presented. This offers the advantages of an automatic reduction in the size of the eigenvalues problem and of a straightforward means of dynamic substructuring. The analytical procedure in this method for dynamic analysis of 3-dimensional cantilevered box beam are described. the result of numerical example is shown to demonstate the efficiency and accuracy of this method. The result form this example agree well those obtained by ANSYS, By using this technique, the number of nodes required in the regular finite element method is reduced and therefore a smaller com-puter can be used.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.660-661
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• 2017

We consider a discrete-time queue with batch geometric arrivals, geometric services, and retention of reneging customers, in which retention probability depends on the number of customers in the system. The steady state distribution of the number of customers in the system is derived.