• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.9-17
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• 2010

Corrective control compensates the stable-state behavior of asynchronous sequential machines so that the closed-loop system can be changed in a desirable way. Using corrective control, we present a novel fault tolerance scheme that overcomes permanent faults for asynchronous sequential machines. When a permanent fault occurs to an asynchronous machine, the fault is not recovered forever while the machine is irreversibly stuck in a set of failure states. But, if the machine has control redundancy in the limited behavior range, corrective control can be applied to solve the fault tolerance problem against permanent faults. We present the condition on detecting permanent faults and the existence condition of an appropriate corrective controller. The design procedure for the proposed controller is described in a case study.

• English Language & Literature Teaching
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• v.17 no.3
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• pp.73-98
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• 2011

This study investigated the feasibility and effectiveness of incorporating oral corrective feedback into the content-based business English writing class. Two types of oral corrective feedback, recasts and metalinguistic feedback, were integrated into business English writing classes to help low intermediate-proficiency Korean university students improve the ability to use the simple past, present progressive, and present perfect tenses correctly in their written production. Prior to the treatments, the subjects had basic grammatical knowledge of the target verb tenses, but they had only limited control over them in their written production. Three groups were formed: recast group that received corrective recasting, metalinguistic group that received metalinguistic clues, and control group that received no oral corrective feedback. The study demonstrated that it was feasible to incorporate recasts and metalinguistic feedback into content-based business English writing classes and that metalinguistic feedback had greater and more endurable effects than recasts on promoting the correct use of the target verb tenses in written production. It can be concluded that oral corrective feedback, metalinguistic feedback in particular, can be used in the business English writing classroom to help students gain greater control over already partially acquired forms and therefore improve their writing accuracy.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.139-147
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• 2014

We address the problem of corrective control for two asynchronous sequential machines in parallel connection. Each asynchronous machine receives the same external input and shows independent state transition characteristics. We propose a novel control scheme in which only one corrective controller is employed so as to make the closed-loop system of each machine match the behavior of the corresponding reference model. Compared with the former method utilizing two corrective controllers, our scheme can reduce the controller size and computational load in controller design. We present the existence condition and design procedure for a state-feedback corrective controller under the assumption that the controlled machines are of input/state type. The design procedure for the proposed controller is described in an illustrative example.

• Journal of IKEEE
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• v.24 no.3
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• pp.727-734
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• 2020

Fault tolerant corrective control for asynchronous sequential machines (ASMs) with transient faults is discussed in this paper. The considered ASM is vulnerable to a kind of faults whose manifestation may arise during transient transitions of the ASM, leading to transient faults occurring in non-fundamental mode. To overcome adverse effects caused by these faults, we present a novel corrective control scheme that can detect and tolerate transient faults in non-fundamental mode. The existence condition and design algorithm for an appropriate fault tolerant controller is addressed in the framework of corrective control theory. The applicability of the proposed control methodology is demonstrated in the FPGA experiment.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.139-146
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• 2015

This paper presents the solution to model matching of switched asynchronous sequential machines by corrective control. We propose a model of switched asynchronous sequential machines, in which the system can have different dynamics of asynchronous machines governed by a pre-determined sequence of switching. The control objective is to derive a corrective control law so that the stable state behavior of the closed-loop system can match that of a prescribed model. A new skeleton matrix is defined to represent the reachability of the switched asynchronous machine, and a novel control scheme is presented that interweaves the switching signal and the corrective control procedure. A design algorithm for the proposed controller is illustrated in a case study.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.1-10
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• 2008

The problem of controlling asynchronous sequential machines is addressed in this paper. Corrective control means to make behavior of an asynchronous sequential machine equal to that of a given model. The main objective is to develope a corrective controller, especially when a model is given as nondeterministic, or a set of reference models. The structure of corrective control system for asynchronous sequential machines is addressed first, followed by description of nondeterministic models. Then, we propose a method for analyzing reachability of asynchronous machines and nondeterministic models. Proposed methods are demonstrated in an example.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.11-19
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• 2008

The problem of controlling asynchronous sequential machines is addressed in this paper Corrective control means to make behavior of an asynchronous sequential machine equal to that of a given model. The main objective is to develope a corrective controller, especially when a model is given as nondeterministic, or a set of reference models. We first review representation of nondeterministic models and model matching problems with nondeterministic models, which are presented in the companion paper. We then propose necessary and sufficient conditions for the existence of corrective controllers and describe their design procedure. To show the applicability, the proposed control scheme is demonstrated in an example.

• Physical Therapy Rehabilitation Science
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• v.5 no.4
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• pp.185-192
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• 2016

Objective: The purpose of this study was to find the limited patterns of middle-aged women in selective functional movement evaluation and analyze the effects of pattern improvement exercises and general control groups on the Health Risk Appraisal (HRA). Design: Randomized controlled trial. Methods: The 31 subjects were physically healthy middle-aged women aged 40-59 living in Seoul, The subjects were randomly divided into an experimental group and a control group. Forty-three physically healthy women were originally recruited and randomly assigned to either the experimental group (n=22) or the control group (n=21). However, due to lack of participation, a total of seventeen subjects in the exercise group and fourteen subjects in the control group participated in the study. All subjects were tested using Selective Functional Movement Assessment (SFMA) and HRA for the baseline measurement and joined an exercise program of their group for one hour per session, twice a week for four weeks. The experimental group was provided with the corrective exercises and the control group was given the general fitness program. A follow-up test was conducted after eight weeks from the baseline measurement. Results: Both experimental and control group showed significant changes in SFMA and HRA scores (p<0.05). In the experimental group and control groups, the SFMA and HRA showed significant improvement from baseline to 4 weeks (p<0.05). Also, in the experimental group, the SFMA was significantly improved from baseline to 8 weeks (p<0.05). For the experimental group, there was a significant improvement in SFMA after 4 weeks compared to the control group (p<0.05). Conclusions: The corrective exercise in the experimental group had a positive effect on the SFMA score as well as the general squat exercise in the control group. The corrective exercise and general control group had the same positive effect on the HRA score.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2484-2491
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• 2009

This paper proposes robust state feedback control of asynchronous sequential machines with model uncertainty. The considered asynchronous machine is deterministic, but its state transition function is partially known before executing a control process. The main objective is to derive the existence condition for a corrective controller for which the behavior of the closed-loop system can match a prescribed model in spite of uncertain transitions. The proposed control scheme also has learning ability. The controller perceives true state transitions as it undergoes corrective actions and reflects the learned knowledge in the next step. An adaptation is made such that the controller can have the minimum number of state transitions to realize a model matching procedure. To demonstrate control construction and execution, a VHDL and FPGA implementation of the proposed control scheme is presented.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.11
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• pp.1125-1131
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• 2011

This paper presents a control theoretic approach to realizing fault tolerance in asynchronous sequential circuits. The considered asynchronous circuit is assumed to work in space environment and is subject to faults caused by total ionizing dose (TID) effects. In our setting, TID effects cause permanent changes in state transition characteristics of the asynchronous circuit. Under a certain condition of reachability redundancy, it is possible to design a corrective controller so that the closed-loop system can maintain the normal behavior despite occurrences of TID faults. As a case study, the proposed control scheme is applied to an asynchronous arbiter implemented in FPGA.