• Journal of The Korean Association For Science Education
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• v.20 no.1
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• pp.137-153
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• 2000

In this study. 'extended science investigation' was conceptualized as a comprehensive science investigation contrasted with exercise of process and skill component and cookbook style experiment. The extended investigations should be pursued for giving opportunity of more authentic science activities in school science. And one of important educational objectives in students' science investigations is to achieve motivation for investigation which drives and triggers further investigations. It can be discerned as positive and negative by its direction and also as internal and external by its cause. The purpose of this study was to describe change of students' motivation for investigation while they were performing the extended science investigations. The subject was 128 7th grader attending coeducational school in Seoul. Questionnaires and students' reports were analysed complementarily to describe students' motivation for investigation. The number of students who showed positive motivation for investigation did not increase in the developed extended investigations than in the directive investigations in textbook, but the cause of positive motivation for investigation has changed largely from task-exclusive factors to task-inclusive factors. In case of negative motivation for investigation, regardless of the kind of investigation task, task-inclusive factors were recognized as the main causes. Among those whose motivation changed during successive extended investigations, the students who showed change from negative to positive were more than the reverse. And the number of positive intrinsic motivation for investigation was increased at the second half of the extended science investigations. So it can be said that there was a desirable change of motivation for investigation at the second half the extended science investigations.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.91-94
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• 2010

응용 프로그램을 실행할 때 프로세스간의 상호 연동이 필요한 경우 통신을 하게 된다. 프로세스간의 통신에서 서비스를 요청하는 프로세스의 상태에 따라 동기(Blocking) 모드와 비동기(Non-blocking) 모드로 나누어진다. 동기 모드는 서비스를 요청받은 프로세스의 작업이 완료할 때까지 서비스를 요청한 프로세스의 상태가 멈추는 방식이고, 비동기 모드는 다른 프로세스에 서비스를 요청한 후 자신은 다른 유용한 작업을 계속 수행할 수 있는 방식으로 통신 상대가 여럿이거나 서비스 수행시간이 긴 작업의 경우 비동기 모드를 사용한다. 프로세스 간의 비동기적인 작업 수행이 이벤트 기반으로 이루어지도록 지원하는 이벤트 알림 시스템은 전자메일(E-mail) 서비스와 유사한 특징이 있다. 전자메일 서비스는 컴퓨터 통신망을 통해 편지를 주고 받을 수 있는 서비스 및 해당 편지를 일컫는 용어로, 본 논문에서는 이전에 제시된 이벤트 알림 시스템의 구성과 잘 알려진 전자메일 서비스의 특징을 파악하여 전자메일 서비스를 이용한 이벤트 알림 시스템의 설계 및 구현 방법을 제시한다.

• 정보화사회
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• s.108
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• pp.76-78
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• 1996

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.635-640
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• 2002

We investigate optimal and suboptimal decision rules for parallel code acquisition in chip asynchronous direct-sequence spread-spectrum systems. The conventional decision rule for parallel acquisition is to choose the largest correlator output of a receiver. However, such a scheme is optimum only for chip synchronous models. In this paper, an optimal decision rule is derived based on the maximum-likehood criterion for chip asynchronous models. A simpler suboptimal decision rule is also discussed. The performance of the optimum and suboptimum decision rules is compared to that of the conventional decision rule. Numerical results show that, for chip asynchronous models, both the optimal and suboptimal decision rules outperform the conventional decision rule.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.103-109
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• 2016

Corrective control for asynchronous sequential machines is a novel automatic control theory that compensates illegal behavior or adverse effects of faults in the operation of existent asynchronous machines. In this paper, we propose a scheme of diagnosing and tolerating faults occurring to input channels of corrective control systems. The corrective controller can detect faults occurring in the input channel to the controlled machine, whereas those faults happening in the external input channel cannot be detected. The proposed scheme involves an outer operator which, upon receiving the state feedback, diagnoses a fault and sends an appropriate command signal to the controller for tolerating faults in the external input channel.

• 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.

• 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.

• Electronics and Telecommunications Trends
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• v.16 no.6 s.72
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• pp.1-8
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• 2001

IMT-2000 비동기 시스템은 단말기, 기지국과 무선망 제어국으로 구성되는 무선 접속망 그리고 핵심망 등으로 구성된다. 특히 IMT-2000 비동기 시스템의 무선망 제어국은 기지국과 접속 기능을 가지는 기지국 정합용 무선 접속 서브 시스템, 무선 트래픽 채널의 소프트 핸드오프 처리 기능을 가지는 트래픽 처리용 무선 접속 서브 시스템, 무선망 제어국을 제어하는 무선망 제어국 제어용 서브 시스템, 그리고 회선 및 패킷 교환망을 수용하는 핵심망 및 타 무선망 제어국과의 접속 기능을 수행하는 망 정합용 무선 접속 서브 시스템으로 구성된다. 본 논문에서는 다양한 서비스 품질 파라미터를 갖는 서비스를 지원하기 위한 전달 기능으로서 ATM을 기반으로 하는 ATM 스위치 망을 IMT-2000 비동기 시스템의 무선망 제어국에 적용하여 무선망 제어국의 각 서브 시스템 간 접속시켜 통신 경로 제공 기능을 수행하도록 하였다. 따라서 기지국과 핵심망 사이를 상호 연결하여 음성 및 데이터의 트래픽 정보와 제어 정보를 전달하는 기능을 수한다. 이와 같이 IMT-2000 비동기 시스템에서는 무선망 제어국 내의 서브 시스템과의 접속은 ATM 스위치를 통하여 사용자의 요구에 따라 가변적으로 필요한 대역폭을 제공함으로써 사용자의 요구에 부합되는 통신 수단을 제공할 뿐만 아니라 기존의 IMT-2000 이전 시스템의 서비스 보다는 훨씬 향상된 품질의 패킷 데이터와 멀티미디어 서비스를 포함하는 오디오, 비디오, 그리고 데이터 서비스를 제공할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.1002-1008
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• 2003

In terrestrial data broadcasting, we are just on the beginning stage in all aspects including implementation and design techniques and only asynchronous data processing has been receiving a little study. In this paper, we therefore propose an efficient processing algorithm for synchronization of asynchronous data by using trigger information to make more diverse service possible with a variety of contents. In the proposed algorithm, trigger data is encapsulated in DSM-CC section and transmitted in a form of MPEG-2 TS. The data is then separated in PC type set-top box and detached asynchronous data and trigger data are stored by the proposed algorithm. Pre-loaded asynchronous data is displayed when STC(system time clock) has the same value as PTS(presentation time stamp). Proper operation of the proposed algorithm was verified by using a content of asynchronous data with extensible markup language(XML) and a declarative application(DA) browser.