• The KIPS Transactions:PartA
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• v.8A no.3
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• pp.189-200
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• 2001

This paper proposes a memory allocation model for Real-Time Linux. The proposed model allows users to create several continuous memory regions in an application, to specify an appropriate region allocation policy for each memory region, and to request memory blocks from a necessary memory region. Instead of using single memory management module in order to support the proposed model, we adopt two-layered structure that is consisted of region allocators implementing allocation policies and a region manager controlling regions and region allocator modules. This structure separates allocation policy from allocation mechanism, thus allows system developers to implement same allocation policy using different algorithms in case of need. IN addition, it enables them to implement new allocation policy using different algorithms in case of need. In addition, it enables them to implement new allocation policy easily as long as they preserver predefined internal interfaces, to add the implemented policy into the system, and to remove unnecessary allocation policies from the system, Because the proposed model provides various allocation policies implemented previously, system builders can also reconfigure the system by just selecting most appropriate policies for a specific application without implementing these policies from scratch.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.5
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• pp.306-316
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• 2003

본 논문에서는 소프트웨어 PLC를 구현하는 방안을 제시하였다. 하드웨어는 표준적인 산업용 PC와 입출력 보드들로 구성된다. 운영체제로는 수십 마이크로초의 정밀한 단위로 태스크들의 스케줄링이 가능한 실시간 리눅스를 사용하였다. 소프트웨어 PLC를 위해 개발한 실시간 태스크들은 실시간 리눅스의 커널 모드에서 실행되며, 사용 목적에 따라 작성된 PLC 프로그램을 해석하고 실행하는 작업을 일정한 주기로 반복한다. 또한 PLC 프로그램을 편리하게 작성할 수 있도록 자체 프로그램 문법을 제안하고 이를 위한 컴파일러도 구현하였다. 이렇게 구현된 PLC는 가격 대비 성능이 우수하며 소규모의 응용분야들에 유용하게 활용할 수 있다.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.277-282
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• 2013

Recently, there is a growing need for an open software platform where developers easily write intelligent motion control applications for smart cars, smart robots, smart factories, and so on. To this end, a general-purpose operating system with rich functionalities and various hardware supports can be a candidate for such a platform, but it is known to have limitations in guaranteeing the responsiveness of individual applications. In this paper, to assess the suitability of Linux to be such a platform, we evaluate the real-time performance of Xenomai-patched Linux on an ARM-based processor Exynos4210 with motion control applications. Experimental results show that it is possible to stably provide motion cycle times below 1ms to such applications even with background workloads.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.10-11
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• 2016

실시간 시스템이란 요청된 작업의 논리적 정확성과 시간적 제약을 만족하게 하는 시스템으로 요청된 작업을 예측 가능한 시간 내에 완료하는 시스템을 말한다. 범용 운영체제인 Linux는 실시간성을 지원하지 않기 때문에 ARM 프로세서(Processor) 기반의 Linux 환경에서도 실시간성을 제공하기 위해 본 연구를 진행한다. 본 연구는 Exynos 5422 ARM 프로세서에서 제공하는 타이머를 활용하여 실시간성을 확보하여 Linux 환경에 대한 실시간성 지원 제약을 해결할 수 있다.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.1036-1042
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• 2013

In this paper, an elderly assistance system is developed based on Xenomai, a real-time development framework cooperating with the Linux kernel. A Kinect sensor is used to recognize the behavior of the elderly and A-star search algorithm is implemented to find the shortest path to the person. The mobile robot also generates a trajectory using a digital convolution operator which is based on a Bezier curve for smooth driving. In order to follow the generated trajectory within the control period, we developed real-time tasks and compared the performance of the tracking trajectory with that of non real-time tasks. The real-time task has a better result on following the trajectory within the physical constraints which means that it is more appropriate to apply to an elderly assistant system.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.436-438
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• 2007

As the sensors and communication technology get advance, the remote health diagnosis for patients and senior persons at home are possible now without visiting doctors in hospitals. A low-power ubiquitous health check device was developed adapting Real-Time Embedded Linux is developed. This ubiquitous device is consisted of three sensors. The wrist type health checking terminal acquires periodically the health data by using a blood pressure sensor, a pulse sensor and a body temperature sensor. It transmits the health data to the access point located at the home center through the ZigBee wireless communication modem. This health data collector or access point device sends the data again to the main server operated in a hospital or health care organization. The health server control continuously the input data and sends an alarm signal to the assigned. doctor and responsible persons using cellular SMS when any dangerous events occur. This wrist type health check device has an embedded linux OS using Intel PAX255 MPU. The developed U-Health system is applicable for checking patients health in remote at home. And their family or related persons in remote site can check the patients health status at any time. They can be assured by receiving SMS record and alarm of emergency case which is transmitted from the health server.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.4
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• pp.369-375
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• 2001

This paper proposes a dual real-time scheduling design under real-time constraints kernel environments. In this paper, we have designed both the real-time kernel and the general kernel that have their different properties to satisfy these properties, that is, interrupt latency, scheduling precision, and message passing. In real-time tasks, interrupt processing should be run. In general kernel, non real-time tasks or general tasks are run. Also, when tasks conflict, it executed the mixed priority scheduling that non real-time kernel executed static scheduling and real-time kernel executed dynamic priority transformation scheduling, that is, least-laxity-first/minimization preemption scheduling. We have compared the results of this study for performance of the proposal real-time kernel with both RT Linux 0.5a and QNX 4.23A, that is, of interrupt latency scheduling precision and message passing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.319-320
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• 2012

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1348-1357
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• 2006

In a hybrid three-layer control architecture(deliberative, sequencing, and reflexive), the lowest reflexive layer consists of resources, actions, an action coordinator, and motion controllers. Because the execution of individual components in the reflexive layer should be done in real-time, each component has to be simple and, due to this reason, the Linux-RTAI(Real-Time Application Interface for Linux) has been used as an operating system. In this paper, a navigation control architecture, which combines the components in the reflexive layer and the navigation-related modules in the sequencing layer, is proposed. And then, as basic components, four actions(Goto, Avoid, Move, and EmergencyStop) are designed. Experimental results confirm the effectiveness of the proposed architecture and the performance of individual associated actions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1590-1594
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• 2012

Depend on delay latency rule for message transmission defined in IEC 61850 standard, the fastest message has to be transferred within 3us. This paper suggests how to structure the real time message transmit test environment of IEC 61850 and develope how to securing IEC 61850 communication performance based on IEC 61850 by measuring delay latency of message transfer on embeded linux system.