• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.93-99
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• 2008

Portable devices generally have limited energy sources, so there is a need to minimize the power consumption of processor using energy conservation methods. One of the most common energy conservation methods is dynamic voltage scaling (DVS). In this paper, we propose a new DVS algorithm which uses workload of application to determine frequency and voltage of processors. The posed DVS algorithm consists of DVS module in kernel and specified function in application. The DVS module monitors the processor utilization and changes frequency and voltage periodically. The other part monitors workload of application. With these two procedures, the processor can change the performance level to meet their deadline while consuming less energy. We implemented the proposed DVS algorithm on PXA270 processor with Linux 2.6 kernel.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.649-650
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• 2008

In order to resolve mechanical limit in HDD, recently, the hybrid hard disk combining HDD and a flash memory was launched. In this paper, we propose a simulator for hybrid hard disk which considers redirection, flushing and spin-down function to complement the difference between HDD and hybrid hard disk. The simulator was implemented in linux kernel 2.6.20 by modifying system calls related with file system. The experiment shows that the power consumption of hybrid hard disk is 47% smaller than that of hard disk in laptop PC.

• Journal of KIISE
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• v.44 no.4
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• pp.363-373
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• 2017

Ext4 file system is widely used in various computing environments such as those of the PC, the server, and the Linux-based embedded system. Ext4, which uses a buffer for block I/O, provides fsync() system call to applications to guarantee the consistency of a specific file. A log of the analytical studies regarding the operation of Ext4 and the improvement of its performance has been compiled, but it has not been studied in detail in terms of kernel versions. We figure out that the behavior of fsync() system call is different depending on the kernel version. Between the kernel versions of 3.4.0 and 4.7.2, 3.4.0, 3.8.0, and 4.6.2 showed behavioral differences regarding the fsync() system call. The latency of fsync() in kernel 3.4.0 is longer than that of the more-advanced 3.7.10; meanwhile, the characteristics of 3.8.0 enabled the disruption of the Ext4 journaling order, but the ordered defect was solved with 4.6.2.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3399-3406
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• 2015

NRD(Network RamDisk) is a scheme which allows a system to use the memory of the remote systems just as his own block device via networking. Basically, it consists of a client requesting an NRD access and server providing the NRD. In this paper, we describe the design, implementation and experiment of the block device driver for accessing the NRD in the Linux kernel(2.6) level. First of all, we have analyzed the flow of processing the requests for accessing the block devices in the traditional Linux kernel and figured out the additional functions required for supporting the NRD. Then we have designed and implemented the device diver of NRD client and NRD server for providing these functions. Finally, we have established a NRD server system, and reviewed its functional feasibility by experimenting the requests of NRD access through the NRD device driver implemented on a NRD client.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.4
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• pp.169-175
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• 2005

In recent, implementation of the embedded system is gradually in the spotlight of world-wide by information technology(IT) engineers. By this time, an implementation of real time system is limited on image acquisition and processing system in practical. In this paper, the USB camera interface system based on the embedded linux OS is implemented using USB 2.0 camera with low cost. This system can obtain image signals into the memory via X-hyper255B processor from USB camera. It is need to initialize USB camera by the Video4Linux for the kernel device driver. From the system image capturing and image processing can be performed. It is confirmed that the image data can be transformed to packet of Network File System(NFS) and connected to the internetwork, then the data can be monitored from the client computer connected to the internetwork.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.815-822
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• 1995

In the conventional UNIX system, the all device driver realized in the kern el. Hence, whenever we want to add a new device driver or change the existin g device driver, the modification of kernel is unavoidable. Generally, it is very difficult to modify the kernel codes.As a method of overcoming this difficulty, a TTY device driver model of user-level is presented in this paper. The basic concept of this model is providing a dynamic reconfiguration of TTY device driver by realizing a user-level server process for TTY device driver. In order to verify the proper y of this model, a prototype of TTY device driver has been realized in the SunOS and Linux environment and evaluated its performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.701-705
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• 2002

This paper describes implementation of IPv6-IPv4 transition toolbox named as 6TALK(IPv6 TrAansLator of Krv6) and some scenarios using 6TALK which enables IPv6 island to connect other IPv6 island or IPv4 island seamlessly. 6TALK implements some transition mechanisms suggested in NGTrans Working Group of IETF. Those mechanisms are composed of basic mechanism, tunneling, and applied mechanism such as DSTM. 6TALK provides functions which enable IPv6 network at the edge of existing network to communicate with IPv4 network by using these transition mechanisms. As major transition mechanisms in 6TALK we adopt NAT-PT/SIIT and DSTM/DSTM options and as implementation environment we use Linux Kernel 2.4.18 and Netfilter framework. Software modules implemented in Linux kernel was ported to hardware box using Motorola MPC 8260 processor. The transition mechanisms used in 6TALK are the ones predicted to be used in initial transition step to IPv6.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.356-361
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• 2006

수많은 동시 사용자를 처리해야 하는 인터넷 서버에서는 다수의 연결을 효율적으로 처리 하는 것이 중요한 문제이다. 기존의 멀티 쓰레드 방식이나 이벤트 드리븐 방식이 가지는 한계를 극복하기 위한 한 가지 대안으로서 네트워크 비동기 입출력 방식을 들 수 있다. 네트워크 비동기 입출력을 요청 한 후에 완료될 때까지 블로킹 되지 않고 즉시 다른 작업을 진행할 수 있는 방식으로서, 하나의 쓰레드에서 다중 연결을 효율적으로 처리할 수 있게 한다. 본 논문에서는 리눅스 커널에 네크워크 비동기 입출력을 구현하고 실험을 통한 성능 분석을 수행하였다.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.8
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• pp.810-816
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• 2007

A security robot system named EGIS-SR is a mobile security robot through one of the new growth engine project in robotic industries. It allows home surveillance through an autonomous mobile platform using onboard cameras and wireless security sensors. EGIS-SR has many sensors to allow autonomous navigation, hierarchical control architecture to handle lots of situations in monitoring home surveillance and mighty networks to achieve unmanned security services. EGIS-SR is tightly coupled with a networked security environment, where the information of the robot is remotely connected with the remote cockpit and patrol man. It achieved an intelligent unmanned security service. The robot is a two-wheeled mobile robot and has casters and suspension to overcome a doorsill. The dynamic motion is verified through $ADAMS^{TM}$ simulation. For the main controller, PXA270 based hardware platform based on linux kernel 2.6 is developed. In the linux platform, data handling for various sensors and the localization algorithm are performed. Also, a local path planning algorithm for object avoidance with ultrasonic sensors and localization using $StarGazer^{TM}$ is developed. Finally, for the automatic charging, a docking algorithm with infrared ray system is implemented.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.198-208
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• 2001

CORBA, DCOM, Java RMI 등과 같은 분산 객체 기술이 분산 응용의 신뢰성을 직접적으로 향상시키지는 못한다. 이러한 분산 객체 기술에 고장 감내성을 추가하여 신뢰성 있는 시스템을 구축하기 위해서 객체 단위의 복제 그룹 관리와 고장 탐지 및 회복 메커니즘이 필요하다. 본 논문에서는 신뢰성 있는 고장 감내성 Java RMI 객체를 개발하기 위하여 고장 탐지와 그룹 관리를 위한 그룹 관리자와 원격 인터페이스를 설계하고, 고장 감내성 클래스를 정의한다. 또한 고장 감내성 객체의 투명한 그룹 참여를 위하여 Naming 클래스와 RMIRegistry를 확장한다. 응용 개발자는 고장 감내성 클래스를 상속함으로써 외부의 도움 없이 간단히 고장 감내성 응용 객체를 개발하여 신뢰성을 높일 수 있다. 100M Ethernet으로 연결된 Linux kernel2.2.1의 PentiumIII머신 3대와 Solaris2,6의 Sun Spar치머신을 클라이언트한 시스템을 사용하고 JDK 1.2.2를 이용하여 설계한 객체를 구현하여 다양한 객체고장 에 대해 복구되는 것을 확인하였다. 성능 평가는 그룹크기에 따른 함수의 응답속도와 메시지 크기에 따른 응답속도를 비교하였다.