• Journal of KIISE:Computing Practices and Letters
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• v.15 no.2
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• pp.89-97
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• 2009

Embedded systems widely used in ubiquitous environments usually employ an event-driven programming model instead of thread-based programming model in order to create a more robust system that uses less memory. However, as the software for embedded systems becomes more complex, it becomes hard to program as a single event handler using the event-driven programming model. This paper discusses the implementation of non-preemptive real-time scheduling theory for the design of embedded systems. To this end, we present an efficient schedulability test method for a given non-preemptive task set using a sufficient condition. This paper also shows that the notion of sub-tasks in embedded systems can overcome the problem of low utilization that is a main drawback of non-preemptive scheduling.

• Journal of KIISE:Software and Applications
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• v.33 no.9
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• pp.802-809
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• 2006

J2ME mobile programs have been widely used as mobile devices like mobile phones become popular. Efficient use of resources in mobile programs is very important because mobile programs are executed in mobile environment with insufficient resources. Moreover, most J2ME programs are event-driven, so effective event handling is important for reliability and efficient use of resource. In this research, we develop a dynamic event analysis system, which can show event handling in real-time. In this system, users can trace only interesting events by selecting some options, and can get event profile after execution.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.901-907
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• 1998

This paper presents a real-time control technique for the development of a ship main engine remote control system, In general several tasks are executed by the event-driven method in real-time system. However when some tasks have time delay components it is difficult to achieve good real-time performance. To cope with this problem a number of timers in most conventional system have been used. In this paper we introduce a real-time control methodology of dealing effectively with tasks including time delay components using one hardware timer. And also a speed control method of main engine which includes critical revolution range a crash astern and a emergency ahead function a switching method of remote control position and a flickering method for the indication of multi-stage alarm are discussed. As long as functions and method are imple-mented as forms of tasks the development of main engine remote control systems can be easy for different types of engines.

• International Journal of Advanced Culture Technology
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• v.4 no.3
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• pp.13-19
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• 2016

The growth of mobile devices in Internet of Things (IoT) leads to a number of remote and controlling system related IoT applications. For instance, home automation controlling system uses client system such web apps on smartphone or web service to access the home server by sending control commands. The home server receives the command, then controls for instance the light system. The web service gateway responsible for handling clients' requests attests an internet latency when an increasing number of end users requests submit toward it. Therefore, this web service gateway fails to detect several commands, slows down predefined actions which should be performed without human intervention. In this paper, we investigate the performance of a web server-side platgorm based event-driven, non-blocking approach called Node.js against traditional thread-based server side approach to handle a large number of client requests simultaneously for remote and controlling system in IoT remote monitoring applications. The Node.JS is 40% faster than the traditional web server side features thread-based approach. The use of Node.js server-side handles a large number of clients' requests, then therefore, reduces delay in performing predefined actions automatically in IoT environment.

• The Transactions of the Korea Information Processing Society
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• v.1 no.1
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• pp.50-62
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• 1994

The majority of database users interact with database systems by manipulating forms. This paper discusses the fundamentals underlying forms and considers low these mechanisms affect the behavior of forms We then review the forms supported by commercial products. None of the packages reviewed provide all of the features that make up an ideal form. We propose a new design that overcomes many of the limitations observed in the packages currently available. The new system is event- driven, object-oriented, supports a hierachy of composite blocks, and is primarily modeless. Forms are defined as top-level blocks and blocks can be either atomic or composite structures with methods directly included in their definition. Messages are passed among form objects. Defining forms with the proposed system is simple because from definitions are similar to type declarations in Pascal.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.78-79
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• 2011

대형시스템의 배터리 관리 시스템은 일반적인 운영체제(Operation System)나 실시간 운영체제(Real Time Operation System)를 사용하여 배터리 관리 시스템을 하는 반면 휴대용 전자정보기기와 같은 소형시스템에서는 유한상태머신(Finite State Machine)을 이용한 배터리 관리 시스템을 사용한다. 이러한 대형시스템은 대부분 고성능을 요구하기 때문에 시스템을 유지하기 위해서는 막대한 비용이 들어간다. 이 결과로 상업적 제품의 가격적인 장점을 위하여 특화된 기능만을 지원하는 유한상태머신을 사용하는 배터리 관리 시스템을 많이 이용하고 있다. 최근에는 멀티미디어 기록 및 재생의 많은 전력소모를 요구하는 모바일 시스템이 많아지므로 콘텐츠 기반 배터리 관리 시스템 등 복잡한 배터리 관리 시스템을 소형기기에 적용하기 위하여 많은 연구가 진행되고 있다. 운영체제를 기반으로 하는 배터리 관리 시스템은 모바일 시스템에 사용하기에는 자체 전력소비가 많으며, 유한상태머신을 사용하는 배터리 관리 시스템은 다양한 요구와 복잡한 배터리 관리 시스템의 기능을 수용할 수 없다. 본 논문에서는 상기 두 가지 경우의 장점을 취한 이벤트 드리븐 프로그래밍(Event-Driven Programming) 방식을 사용하여 배터리 관리 시스템을 제안하고 제안된 시스템이 SBS(Smart Battery Data Specification v1.1)[1]를 만족할 수 있음을 보였다.

• International journal of advanced smart convergence
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• v.5 no.3
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• pp.32-39
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• 2016

With the help of a small wearable device, patients reside in an isolated village need constant monitoring which may increase access to care and decrease healthcare delivery cost. As the number of patients' requests increases in simultaneously manner, the web service gateway located in the village hall encounters limitations for performing them successfully and concurrently. The gateway based RESTful technology responsible for handling patients' requests attests an internet latency in case a large number of them submit toward the gateway increases. In this paper, we propose the design tasks of the web service gateway for handling concurrency events. In the procedure of designing tasks, concurrency is best understood by employing multiple levels of abstraction. The way that is eminently to accomplish concurrency is to build an object-oriented environment with support for messages passing between concurrent objects. We also investigate the performance of event-driven architecture for building web service gateway using node.js. The experiments results show that server-side JavaScript with Node.js and MongoDB as database is 40% faster than Apache Sling. With Node.js developers can build a high-performance, asynchronous, event-driven healthcare hub server to handle an increasing number of concurrent connections for Remote Healthcare Monitoring System in an isolated village with no access to local medical care.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.89-100
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• 2011

The MAGLEV (Magnetically Levitated Vehicle) system, which is under commercialization as a new transportation system in Korea, is operated by means of unmanned automatic control system. Therefore the plan of train operation should be carefully established and validated in advance. In general, when making the train operation plan, the statistically predicted traffic data is used. However, traffic wave can occur when real train service is operated, and the demand-driven simulation technology is required to review train operation plans and service qualities considering traffic wave. This paper presents a method and model to simulate the MAGLEV's operation considering continuous demand changes. For this purpose, we employed the discrete event model which is suitable for modeling the behavior of railway passenger transportation, and modeled the system hierarchically using DEVS (Discrete Event System Specification) formalism. In addition, through the implementation and experiment using DEVSim++ simulation environment, we tested the feasibility of the proposed model and it is also verified that our demand-driven simulation technology could be used for the prior review of the train operation plans and strategies.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.1-9
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• 2010

This paper describes parallel event-driven remote IT convergence applications which are a combination of traditional industry and IT Technology including advanced communication. In IT convergence system, events can occur currently from many sensors of devices or users. And IT convergence system must have a parallel processing method. In this paper, the parallel processing method was implemented using a thread and we developed a connection method between a device and a mode of communication which is a wireless communication or a power line communication. In addition to that, we developed object modeling, device, user and event modeling, based on XML (eXtensible Markup Language) using object-oriented modeling method. To efficiently show results in real time, systems provide various graphic user interfaces such as a bar graph, a table, and a combination of the two.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.1
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• pp.33-40
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• 2000

In this paper, an integrated method for the path planning and motion control of wheeled mobile robots using a hybrid system model and control is presented. The hybrid model including the continuous dynamics and discrete dynamics with the continuous and discrete state vector is derived for a two wheel driven mobile robot. The architecture of the hybrid control system for real time path planning and following is designed which has the 3-layered hierarchical structure : the discrete event system using the digital automata as the higher process, the continuous state system for the wheel velocity controls as the lower process, and the interface system as the interaction process between the continuous system as the low level and the discrete event system as the high level. The reference motion commands for autonomous navigation are generated by the abstracted motion in the discrete event system. The motion control tasks including the feasible path planning and autonomous motion control with various initial conditions are investigated as the applications by the simulation studies.