• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.33-43
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• 2001

This paper presents a secure Linux OS in which multi-level security functions are implemented at the kernel level. Current security efforts such as firewall or intrusion detection system provided in application-space without security features of the secure OS suffer from many vulnerabilities. However the development of the secure OS in Korea lies in just an initial state, and NSA has implemented a prototype of the secure Linux but published just some parts of the technologies. Thus our commercialized secure Linux OS with multi-level security kernel functions meets the minimum requirements for TCSEC B1 level as well kernel-mode encryption, real-time audit trail with DB, and restricted use of root privileges.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.45-52
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• 2008

As multiple functions arc required in a robot controller, RTOS(Real Time Operating System) should be adopted to manage complex situations, such as choosing most urgent task among competing ones. In this paper, we implemented RTAI(Real Time Application Interface) based robot controller for wafer handling robots including graphic simulator. We showed how multiple tasks are organized and also explained in detail about task priorities and execution periods. Finally, we presented simulation results.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.112-114
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• 2001

최근 멀티미디어 서비스에 대한 사용자의 요구가 증가되고 있다. 그러나 서버 시스템은 이러한 멀티미디어 데이터에 대해 사용자들에게 효율적으로 공급하지 못한다. 본 논문에서는 기존의 운영체제에 멀티미디어 데이터 전송을 효율적으로 만족시키기 위한 방안으로 RTP(Real-time Transport Protocol) 데이터 처리를 SIO(Special Input/Output) 메커니즘 커널에 내장하는 SPTPIO(Special RTP Input/Output) 모듈을 제안한다.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.6
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• pp.21-27
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• 2015

We analyze the problem that is occurring when using parity mode transformation required for 9 bit serial communication under Linux environment and propose the solution. The parity mode change is used for 9 bit serial communication in the Linux that by nature supports only 8 bit serial communication. delay (around OS tick) arises. Our analysis shows that the cause is minimum length of waiting time to transmit data remained in Tx FIFO buffers. A modified Linux serial driver proposed in this paper decreases the delay less than 1ms by using accurate time delaying. Despite various system communication interfaces, enormous existing standards and system have adopted RS-232 serial communication, and the part of them have communicated by 9bit serial.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1082-1091
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• 2007

In this paper, we developed a new hybrid mobile robot which can climb stairs and go over thresholds by crawl gait with embedded real-time control software. This robot is also categorized into hybrid robot that has advantages of wheeled mobile robot and legged mobile robot, but adopts gait feature of crocodile named belly crawl. We imitated the belly crawl using four legs of 2 DOF, four omni-directional wheels, and embedded control software which controls legs and wheels. This software is developed using RTAI/Linux, real-time drivers. As a result, the new hybrid mobile robot has crawl gait. Using this feature, the new hybrid mobile robot can climb stairs and go over thresholds just by path planning of each leg with size of stairs and thresholds, and computing the movement distance of robot body center without considering stability. The performance of our new hybrid mobile robot is verified via experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.720-725
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• 2008

This paper proposes a system architecture for USN with a service robot to provide more active assisted living services for elderly persons by monitoring their mental and physical well-being with USN environments at home, hospital, or silver town. Sensors embedded in USN are used to detect preventive measures for chronic disease. Logged data are transferred to main controller of a service robot via wireless channel in which the analysis of data is performed. For the purpose of handling emergency situations, it needs real-time processing on gathering variety sensor data, routing algorithms for sensor nodes to a moving sink node and processing of logged data. This paper realized multi-hop sensor network to detect user movements with biometric data transmission and performed algorithms on Xenomai, a real-time embedded Linux. To leverage active sensing, a mobile robot is used of which task was implemented with a priority to process urgent data came from the sink-node. This software architecture is anticipated to integrate sensing, communication and computing with real-time manner. In order to verify the usefulness of a proposed system, the performance of data transferring and processing on a real-time OS with non real-time OS is also evaluated.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.201-212
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• 2002

This paper proposes a reconfigurable scheduler model that can support various real-time scheduling algorithms. The proposed model consists of two hierarchical upper and lower components, task scheduler and scheduling framework, respectively. The scheduling framework provides a job dispatcher and software timers. The task scheduler implements an appropriate scheduling algorithm, which supports a specific real-time application, based on the scheduling framework. If system developers observe internal kernel interfaces to communicate between two hierarchical components, they can implement a new scheduling algorithm independent of complex low kernel mechanism. Once a task scheduler is developed, it can be reused in a new real-time system in future. In Real-Time Linux (5), we implemented the proposed scheduling framework and several representative real-time scheduling algorithms. Throughout these implementations, we confirmed that a new scheduling algorithm could be developed independently without updates of complex low kernel modules. In order to confirm efficiency of the proposed model, we measured the performance of representative task schedulers. The results showed that the scheduling overhead of proposed model, which has two separated components, is similar to that of a classic monolithic kernel scheduler.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.3
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• pp.139-150
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• 2015

The major components of IoT(Internet of Things) environment are IoT devices rather than the conventional desktop computers. One of the intrinsic characteristics of IoT devices is diversity in view of data type and data access method. In addition, IoT devices usually deal with real-time data. In order to use such IoT data for internal business or cloud services, an IoT platform capable of easy domain management and consistent data access interface is required. This paper proposes a Linux FUSE-based virtual file system connecting IoT devices on POSIX file system view. It is possible to manage IoT domain with the native Linux utilities such as mkdir, mknod, ls and find in the file system. Also, the file system makes it possible to access or control IoT devices through POSIX interface such as open(), read(), write() or close() without any separate APIs or utilities. A test result shows that the management performance of the file system is lower than that of linux file system negligibly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.88-95
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• 2004

The previous disk scheduling schemes for best-effort applications do not guarantee the real-time requirement of multimedia objects and the real-time disk scheduling schemes do not satisfy throughput of multimedia server. So, this paper propose a two-step disk scheduling scheme to satisfy the requirement of best-effort as well as soft real-time applications. This scheme is based on the round robin algorithm that imposes different weights on the best-effort task and the real-time one. The experiment results on the Linux kernel have shown that both best-effort tasks and real-time tasks could get fair service.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.213-222
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• 2008

The existing approaches for the music application have not considered a real-time multi-tasking model. So, it suffers from a high complexity and a low flexibility in design as well as lack of predictability for the timely execution of critical tasks. In this paper, we design a new concurrent tasking architecture for a real-time embedded music system and examine if all real-time tasks can finish execution within their respective time constraints. The design is implemented on the Linux based Xhyper272 Board that uses the Intel Bulverde microprocessor.