• 한국통신학회논문지
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• 제27권10A호
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• pp.990-999
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• 2002

The object-oriented(OO) distributed real-time(RT) programming movement started in 1990's and is growing rapidly at this turn of the century. Distributed real-time simulation is a field in its infancy but it is bounded to receive steadily growing recognition for its importance and wide applicability. The scheme is called the distributed time-triggered simulation scheme which is conceptually simple and easy to use but widely applicable. A new generation object oriented(OO) RT programming scheme is called the time-triggered message triggered object(TMO) programming scheme and it is used to make specific illustrations of the issues. The TMO structuring scheme is a general-style components structuring scheme and supports design of all types of component including hard real time objects and non real time objects within one general structure.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.775-779
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• 2011

As the technology of multimedia sensor networks is desired in large numbers of applications nowadays, real-time service becomes one of the most important research challenges. Even though lots of related works have been conducted to meet this requirement in several ways, the specific traffic model for real-time has not been taken yet. Thus, it causes lack of adaptability of those approaches in real deployment. To solve this problem, in this paper, we model the application via (m,k)-firm streams which have weakly hard real-time property. And then, a novel forwarding scheme based on modified DBP (Distance-Based Priority) is proposed by considering local-DBP and stream DBP together. Local-DBP can contribute to identify the detailed causes of unsatisfied quality, that is, network congestion or wireless link failure. Simulation results reveal that (m,k)-firm is a good traffic model for multimedia sensor networks and the proposed scheme can contribute to guarantee real-time requirement well.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.353-358
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• 2011

In this paper, we have introduced a Missile In the Loop Simulation(MILS) Software developed for the missile ground test, which is based on a commercial hard real-time operating system(OS) on Windows platform called as Real-Time eXtension(RTX). MILS software makes it possible to test overall system functions of a integrated missile on the ground in the flight conditions by real-time imitating its inertial data. By means of MILS, we have performed missiles ground tests, which result in successful real flight tests.

• 대한전자공학회논문지
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• 제24권4호
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• pp.559-567
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• 1987

In this paper, the real time simulation of continuous dynamic system was performed by general integration algorithms using multiprocessor. For the stable simulation, the relation between stability of integration method and integration step-size was investigated from the stability graph. As a typical illustration, the real-time digital simulation and the real-time hard-ware-in-the-loop simulation of flight control system were performed and reviewed. Moreover through the real-time simulation, the design verification and performace test of flight control system could be evaluated. The computer used for simulation is AD10, which is a very high-speed special-purpose computer designed specifically for a time-critical simulation of large and complex models of dynamic systems. The simulation validity is demonstrated by comparing hardware simulation results with software simulation results.

• 정보학연구
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• 제4권2호
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• pp.25-36
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• 2001

실시간 커널은 시간적인 요소를 가장 핵심으로 고려하여 설계된다. 따라서 실시간 커널은 작은 용량을 가지며 빠르게 예측할 수 있어야 한다. 또한 실시간 스케줄링에 요구되는 많은 변화들을 통해서 실시간 커널에 융통성을 부여해야 한다. 본 논문에서 제안한 분산 이중 실시간 커널 시스템은 실시간 제약들을 고려한 실시간 커널과 일반적인 커널의 특성을 가지도록 설계한다. 실시간 제약 조건인 인터럽트 지연 시간, 스케줄링의 정확성, 메시지 전달시간을 만족하기 위하여 실시간 커널에는 실시간 태스크 처리와 인터럽트 처리, 타이밍을 처리하도록 하였고 비실시간 커널은 일반적인 태스크를 처리하도록 한다. 또한, 기존의 실시간 커널인 RT-Linux, QNX와 제안한 실시간 커널이 인터럽트 지연, 스케줄링 정확성, 메시지 전달시간 등을 비교 분석함으로써 실시간 제약조건을 만족함을 보인다

• 한국통신학회논문지
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• 제21권11호
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• pp.2801-2809
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• 1996

실시간 시스템을 위한 다중프로세서 환경에서 스케줄링 문제는 대부분 NP hard 문제로서 최적의 해를 구하는 것은 매우 어려우나, 휴리스틱에 의한 여러 효율적인 방법이 계속 연구되고 있다. 이중 주기적인 타스크들을 여러 프로세서에 어떻게 배치하면서 실시간성을 보장하는 가에 대한 연구도 진행되고 있다. 그 동안 연구되었던 배치 방법인 RMNF, RMFF, FFDUF 및 NEXT-Fit-M과 유사한 그룹에 의한 배치로 보다 적은 프로세서를 요구하는 방식 및 알고리즘 네가지를 제안하고, 주기적인 타스크들을 임의로 발생시켜 시뮬레이션을 수행하였다. 이러한 분석결과 제안한 방법이 기존의 방식보다 프로세서 수를 더 줄일 수 있음을 보였다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권6호
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• pp.173-178
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• 2014

제시된 스케줄링 기법은 병렬처리 기법을 활용하여 실시간 작업들의 데드라인 제약과 결함 포용 제약을 만족하면서 멀티코어 프로세서의 에너지 소모 효율성을 향상시켰다. 최소 에너지 소모량 스케줄을 찾는 것은 NP-hard 문제이므로, 제시된 기법은 다항식의 시간 내에 최소 에너지 소모량에 근접하는 스케줄을 찾는다. 제시된 기법은 연관된 최신 기법과 비교하여 높은 병렬처리 속도는 물론 낮은 병렬처리 속도에서도 에너지 소모량이 현격하게 낮았으며, 에너지 소모량을 최대 86% 줄였다.

• Journal of Information Technology Applications and Management
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• 제14권3호
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• pp.227-236
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• 2007

Students in cyber universities can take every course because there are no physical constraints such as class rooms. On the other hand. cyber universities should take a heavy burden to schedule real-time exams in a designated time period. Any two courses a student takes must not be simultaneously allocated to a time slot in such a schedule. It is well known that the complexity of this kind of scheduling problem increases exponentially as the number of courses does. This research provides a heuristic method to make on-line real-time exam timetables with minimal exam time span. It considers the constraint of not allocating courses a student takes to simultaneous exam time and prioritizes courses by the number of students.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3361-3377
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• 2014

Synchronous computing models provided by real-time synchrony protocols, such as TTA [1] and PALS [2], greatly simplify the design, implementation, and verification of real-time distributed systems. However, their application to real systems has been limited since their assumptions on underlying systems are hard to satisfy. In particular, most previous real-time synchrony protocols hypothesize the existence of underlying fault tolerant real-time networks. This, however, might not be true in most soft real-time applications. In this paper, we propose a practical approach to a synchrony protocol, called Quality-Aware PALS (qPALS), which provides the benefits of a synchronous computing model in environments where no fault-tolerant real-time network is available. qPALS supports two flexible global synchronization protocols: one tailored for the performance and the other for the correctness of synchronization. Hence, applications can make a negotiation flexibly between performance and correctness. In qPALS, the Quality-of-Service (QoS) on synchronization and consistency is specified in a probabilistic manner, and the specified QoS is supported under dynamic and unpredictable network environments via a control-theoretic approach. Our simulation results show that qPALS supports highly reliable synchronization for critical events while still supporting the efficiency and performance even when the underlying network is not stable.

• 한국IT서비스학회지
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• 제13권1호
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• pp.209-220
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• 2014

Most of monitoring systems in logistics industry have limitations on monitoring container information in real-time. And customers only could check information gathered from certain points through web browser. That is why it is very hard to take actions in advance when emergency situation has happened. But if customers could check information such as position and status of freight in real-time through their mobile devices, they could take prompt actions. So, in this study, mobile application based on mobile devices is developed to monitor position and status information of the container in real-time. Entire devices monitoring container in aspect of logistics security are handled by workers in the field. So it is strongly required to develop monitoring system operated in mobile devices. For that reason this study aims to develop mobile application in order to monitor information related to container security and safety in real-time.