• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.46 no.4
• /
• pp.39-48
• /
• 2009

Asynchronous sequential machines, or clockless logic circuits, have several advantages over synchronous machines such as fast operation speed, low power consumption, etc. In this paper, we propose a novel robust controller for input/output asynchronous sequential machines with uncertain state transitions. Due to model uncertainties or inner failures, the state transition function of the considered asynchronous machine is not completely known. In this study, we present a formulation to model this kind of asynchronous machines ana using generalized reachability matrices, we address the condition for the existence of an appropriate controller such that the closed-loop behavior matches that of a prescribed model. Based on the previous research results, we sketch design procedure of the proposed controller and analyze the stable-state operation of the closed-loop system.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2014.01a
• /
• pp.271-272
• /
• 2014

현재 디지털 시스템 설계가 필요한 모든 유한 상태머신을 설계에는 필수적 밀리 모델이나 무어 모델이 들어간다. 그러나 각각의 기기와 기능에 따라서 밀리 모델과 무어 모델 중 어느 모델이 디지털 논리회로 설계에 효율적인지 판단이 모호한 상황이다. 이를 위해 본 논문에서는 유한 상태머신의 하나인 벤딩머신을 대상으로 밀리 모델과 무어 모델을 사용하여 설계한 후, 설계의 복잡도와 구현 게이트 수를 구하여 각 모델의 효율성에 대해 비교 분석하고자 한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10a
• /
• pp.568-570
• /
• 2004

Harel과 UML에서 제공하는 기존 개념의 상태챠트는 실시간 작업들의 동시성(concurrency)을 모델링하기 어려운 단점을 가진다. 본 논문에서는 이러한 문제점을 해결하기 위해 재진입 상태머신과 재진입 상태챠트라는 새로운 개념을 제안한다. 재진입 상태머신은 병렬적으로 실행할 작업들을 교차수행(interleave)함으로서, 상태챠트로 표현되는 실시간 작업들의 동시성(Concurrency)물 효과적으로 지원할 수 있다 이러한 재진입 상태머신을 기반으로, 재진입 상태챠트는 간결하고 풍부한 표현 의미를 제공하며, 아울러 동시적으로 처리되는 행동 모델들을 구체적으로 표현할 수 있다. 재진입 상태머신과 재진입 상태챠트를 이용하여 실시간 시스템을 구현하면 프로세스간 흑은 쓰레드간의 스위칭이 불필요해짐에 따라 그에 따른 실행 오버헤드를 최소화할 수 있다.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1935_1936
• /
• 2009

기울기 S=2인 톱니맵 $S_2$(x) 와 텐트맵 $S_2$(x), 두 혼돈맵들을 차례로 연결시킨 합성맵을 사용하여 합성상태머신을 설계하였다. 혼돈맵의 합성논리를 이용하여 설계한 합성상태머신에서 발생하는 난수적인 상태들을 그래프적으로 보였으며, 난수적인 상태들의 주기는 정밀도와 이산화된 진리표에 따른 길이를 발생시켰다.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.5
• /
• pp.253-261
• /
• 2013

In this paper, we study the problem of controlling composite asynchronous sequential machines. The considered asynchronous machine consists of two input/state machines in cascade connection, where the output of the front machine is delivered to the input channel of the rear machine. The objective is to design a corrective controller realizing model matching such that the stable state behavior of the closed-loop system matches that of a reference model. Since the controller receives the state feedback of the rear machine only, there exists uncertainty about the present state of the front machine. We specify the existence condition for a corrective controller given the uncertainty. The design procedure for the proposed controller is described in a case study.

• Journal of KIISE
• /
• v.41 no.10
• /
• pp.774-784
• /
• 2014

Studies of fault-injection into state machine diagram have been studied for generating robustness test cases. Conventional studies have, however, tended to inject too many faults into diagrams because they only have considered structural aspects of diagrams. In this paper, we propose a method that aims to reduce the number of injected fault without a decrease in effectivenss of robustness test. A proposed method is demonstrated using a microwave oven sate machine diagram and evaluated using a hash table state machine diagram. The result of the evaluation shows that the number of injected faults is decreased by 43% and the number of test cases is decreased by 63% without a decrease in effectiveness of hash table robustness test.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.47 no.4
• /
• pp.7-14
• /
• 2010

Stable-state behaviors of asynchronous sequential machines represented as finite state machines can be corrected by feedback control schemes. In this paper, we propose a state feedback control scheme for input/state asynchronous machines with uncertain transitions. The considered asynchronous machine is deterministic, but its state transition function is partially known due to model uncertainty or inner logic errors. The control objective is to compensate the behavior of the closed-loop system so that it matches a sub-behavior of a prescribed model despite uncertain transitions. Furthermore, during the execution of corrective action, the controller reflects the exact knowledge of transitions into the next step, i.e., the range of the behavior of the closed-loop system can be enlarged through learning. The design procedure for the proposed controller is described in a case study.

• Journal of KIISE:Software and Applications
• /
• v.36 no.6
• /
• pp.443-450
• /
• 2009

In an earlier development phase, the simulation technique is one of the key analysis methods for checking the correctness of system's functional requirements. In general, simulation is manually or randomly performed by executing state machine diagrams according to the requirement scenarios. Therefore, simulation is one of the most effort-consuming tasks. In this paper, an automatic simulation technique of state machine diagrams is provided according to the scenarios of the sequence diagrams. It is not easy to generate detailed simulation traces from sequence diagrams due to different abstraction levels between sequence diagrams and state machine diagrams. In order to adjust for different abstraction levels, state machine diagrams and sequence diagrams are transformed into LTS models and compositional analysis and transition reduction are performed. After checking behavior conformance between them, detailed simulation traces for the state machine diagrams are generated. These simulation traces are used not only for performing automatic simulation but also for assisting analyzers to reach a specific system state in order to guide further efficient simulation.

• Journal of KIISE:Software and Applications
• /
• v.35 no.1
• /
• pp.12-21
• /
• 2008

As the usage of computer systems is increasing in our lives, the reliability and safely of these systems need to be thoroughly checked through the verification techniques. As a basic formalism for several modeling methods, the finite state machine (FSM) is widely used in specification and verification of system models. And there is a technique for ing internal events of FSM in order to effectively analyze the system. However, this technique does not handle the state explosion problem since it can be applied after completely generating all the state space of the system. In this research, we provide a new approach for efficiently representing concurrent properties of FSM, the slice model and provide an efficient transition reduction method based on the slice model. Our approach is effective in time and space perspective since it is peformed by partially generating the needed system states while the existing abstraction technique can be applied to all the system states.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.3
• /
• pp.40-47
• /
• 2011

This paper addresses the problem of fault detection and tolerance for asynchronous sequential machines using state feedback control. The considered asynchronous machine is affected by intermittent faults. When intermittent faults occur, the machine undergoes unauthorized state transitions and, for a finite duration, remains at the fault state, not responding to the change of the external input. In this paper, we postulate the scheme of detecting intermittent faults and present the existence condition and design algorithm for a robust state feedback controller that overcomes the adversarial effect of intermittent faults. We also undertake a comparative study between the previous control scheme for transient faults and the present strategy for intermittent faults. The design procedure for the proposed controller is described in a case study.