• Industrial Engineering and Management Systems
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• v.8 no.3
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• pp.155-161
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• 2009

We focus on discrete event systems with a structure of parallel processing, synchronization, and no-concurrency. We use max-plus algebra, which is an effective approach for controller design for this type of system, for modeling and formulation. Since a typical feature of this type of system is that the initial schedule is frequently changed due to unpredictable disturbances, we use a simple model and numerical examples to examine the possibility of applying the concepts of the feeding buffer and the project buffer of critical chain project management (CCPM) on max-plus linear discrete event systems in order to control the occurrence of an undesirable state change. The application of a CCPM-based framework on a max-plus linear discrete event system was proven to be effective.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.179-180
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• 2015

에이전트 기반 마이크로 시뮬레이션에서 많이 사용하는 단순 전이확률(transition probability) 행렬이나 추정된 전이확률함수는 단순화하는 과정에서 정보 손실이 발생하고 복잡한 모델에서 사용할 수 없고 전이확률이 시간에 따라 변화하면 시간 변화를 따르는 별도의 추정이 필요로 한다. 본 연구는 이런 기존 방법의 한계를 해결하기 위하여, 다차원 전이확률표들을 이용해서 이벤트 발생을 결정함으로써 정보 손실을 줄이고 단순 행렬이나 함수로 표현하기 어려운 경우에도 이벤트 발생을 재현하고, 시간 독립적인 전이확률표를 이용해서 이벤트 발생을 결정함으로써 시간 변화를 별도로 추정하지 않고 이벤트 발생을 예측할 수 있는 방법을 제안하는데 있다.

• Structural Engineering and Mechanics
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• v.49 no.3
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• pp.411-425
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• 2014

This paper presents the processing of nonlinear features associated with a damage event by quadratic time-frequency distributions for damage identification in a frame structure. A time-frequency distribution is a function which distributes the total energy of a signal at a particular time and frequency point. As the occurrence of damage often gives rise to non-stationary, nonlinear structural behavior, simultaneous representation of the dynamic response in the time-frequency plane offers valuable insight for damage detection. The applicability of the bilinear time-frequency distributions of the Cohen class is examined for the damage assessment of a frame structure from the simulated acceleration data. It is shown that the changes in instantaneous energy of the dynamic response could be a good damage indicator. Presence and location of damage can be identified using Choi-Williams distribution when damping is ignored. However, in the presence of damping the Page distribution is more effective and offers better readability for structural damage detection.

• The Journal of Korea Robotics Society
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• v.3 no.1
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• pp.42-51
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• 2008

Robots need to understand as much as possible about their environmental situation and react appropriately to any event that provokes changes in their behavior. In this paper, we pay attention to topological relations between spatial objects and propose a model of robotic cognition that represents and infers temporal relations. Specifically, the proposed model extracts specified features of the cooccurrence matrix represents from disparity images of the stereo vision system. More importantly, a habituation model is used to infer intrinsic spatial relations between objects. A preliminary experimental investigation is carried out to verify the validity of the proposed method under real test condition.