• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.3
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• pp.158-166
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• 2008

These days, mobile embedded systems adopt flash memory capable of XIP feature since they can reduce memory usage, power consumption, and software load time. XIP provides direct access to ROM and flash memory for processors. However, using XIP incurs unnecessary degradation of applications' performance because direct access to ROM and flash memory shows more delay than that to main memory. In this paper, we propose a memory management framework, dynamic XIP, which can resolve the performance degradation of using XIP. Using a constrained RAM cache, dynamic XIP can dynamically change XIP region according to page access pattern to reduce performance degradation in execution time or energy consumption resulting from native XIP problem. The proposed framework consists of a page profiler gathering applications' memory access pattern using PMU and an XIP manager deciding that a page is accessed whether in main memory or in flash memory. The proposed framework is implemented and evaluated in Linux kernel. Our evaluation shows that our framework can reduce execution time at most 25% and energy consumption at most 22% compared with using XIP-only case adopted in general mobile embedded systems. Moreover, the evaluation shows that in execution time and energy consumption, our modified LRU algorithm with code page filters can reduce more than at most 90% and 80% respectively compared with applying just existing LRU algorithm to dynamic XIP.

• 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 Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.43-49
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• 2011

A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome this problem clearly, this paper describes an improved backup protection coordination scheme using an IEC 61850-based distance relay for transformer backup protection. IEC 61850-based IED(Intelligent Electronic Device) and the network system based on the kernel 2.6 LINUX are realized to verify the proposed method. And laboratory tests to estimate the communication time show that the proposed coordination method is reliable enough for the improved backup protection scheme.

• Convergence Security Journal
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• v.7 no.4
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• pp.123-131
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• 2007

Recently, various threat and security incident are occurred for unspecified individuals, and this problem increases as the rapid of information sharing through Internet. The using of Information Security System such as IDS, Firewall, VPN etc. makes this problem minimal. However, professional knowledge or skill is needed in that case, normal user can't operate the Information Security System. This paper designs and implements File Access Control Module(FACM) to use easily for normal user against malicious threats and attacks. The FACM can exclude from malicious threats and attacks based on operation system rather than detection of threats and attacks. The FACM is working not only Windows System but also Linux System, and the FACM has effect on access control, integrity and non-repudiation for a file with an access control over files on the each OS that are used by multi-user.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1255-1266
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• 2014

This thesis presents MPU module, Base board and sensor module which are efficient industrial control through design and manufacture as developing S5PV210 CPU of SAMSUNG used by ARM Cortex-A8 based on Android which is Open mobile platform is installed to embedded system. Data for temperature and humidity which are received by sensor module proved the suitability and validity for the real time framework design as implementing application program employed the smart phone App with hybrid application based on DB of web server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1290-1300
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• 2016

Recently, various middle box services have been developed and applied to provide network functions to end nodes of the network. Especially, network virtualization is increasingly proceeding by applying the virtualization technologies of cloud computing field to network field, and network platforms for various flexible services are being developed to connect among the virtual network devices. Carrier-grade Network Address Translation (CGNAT) is also one of these flexible network services. This paper designs and implements the DPDK-based CGNAT framework that provides flexibility and maximizes address translation throughput. Our framework achieves 15.5 times higher throughput than the address translation service by Linux kernel.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.129-138
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• 2018

As recent applications are requiring more CPUs for their performance, manycore systems have evolved. Since existing operating systems do not provide performance scalability in manycore systems, Azalea, a multi-kernel based system, has been developed for supporting performance scalability. Unikernel is a new operating system technology starting with the concept of a library OS. Applying unikernel to Azalea enables an improvement in performance. In this paper, we first analyze the current technology trends of unikernel, and then discuss the applications and effects of unikernel to Azalea. Azalea-unikernel was built in a single image consisting of libOS, runtime libraries, and an application, and executed with the desired number of cores and memory size in bare-metal. In particular, it supports source and binary compatibility such that existing linux binaries can be rebuilt and executed in Azalea-unikernel, and already built binaries can be run immediately without modification with a better performance. It not only achieves a performance enhancement, it is also a more secure OS for manycore systems.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.323-326
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• 2024

본 연구에서는 커널 퍼저인 Syzkaller 를 사용하여 리눅스 커널의 네트워크 서브시스템을 퍼징하고 그 결과를 분석하여, 높은 커버리지를 달성하기가 왜 어려운지 분석하고 이를 개선하기 위한 방법들을 제안한다. 첫 번째 실험에서는 TCP 및 IPv4 소켓과 관련된 시스템 콜 및 매개변수만 허용하여 리눅스 커널 네트워크 퍼징을 진행하고, 두 번째 실험에서는 Syzkaller 가 지원하는 모든 시스템 콜을 포함하도록 범위를 확장한다. 첫 번째 실험 결과, 퍼징 시작 약 55 시간만에 TCP 연결 수립에 성공하였다. 두 번째 실험 결과, 첫 번째 실험보다 전반적인 커버리지와 라우팅 서브시스템의 커버리지는 개선되었으나 TCP 연결 수립에는 실패하였다. TCP 연결 수립을 위해서는 서버의 IP 주소 및 포트번호를 클라이언트가 무작위 입력 생성을 통해 맞혀야 하는데, 이 과정에서 시간이 오래 걸리기 때문에 연결 수립이 쉽게 이루어지지 않는 것으로 분석된다. 추가적으로, 본 연구에서는 TCP 연결 수립을 쉽게 하기 위한 하이브리드 퍼징, IP 패킷 포워딩 허용, 패킷 description 없이 퍼징 등 Syzkaller 를 이용하여 리눅스 커널 네트워크 서브시스템을 더 효율적으로 퍼징할 수 있는 방법들을 제안한다.

• Journal of Convergence Society for SMB
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• v.2 no.1
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• pp.51-58
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• 2012

Android platform is a powerful operating system developed on Linux 2.6 Kernel, and provides many features such as comprehensive libraries, a multimedia environment, and powerful interface for phone applications. Since Android is an open operating system, which can be installed in any vendors's equipments. Current smartphones as well as netbooks, navigations, car PCs, tablet PCs, Industrial PCs are used in various fields. It is difficult a lot that to mount to other devices on the Android platform or new devices. In this Paper, The process that data that occurred from a hardware was passed to the highest application and Android platform system for managing hardware devices were analyzed. Building Android & driver compilation environment, How to support the protocol for the use of WiFi in the kernel, How to Mount a WiFi device in the kernel, Device driver registration for the Android platform, WiFi Management Service Daemon (wpa_supplicant) and IP allocation services daemon (dhcpcd) registration, How to create a socket for communication between the daemon (wpa_supplicant) and HAL have been presented. In the experiment using the proposed method, WiFi devices were mounted on the Android platform in the X-86 & ARM family. Understanding the whole process of control flow in Android hierarchy is very important to porting a new device on it. The process included in this paper can help technicians who might encounter the obstacles in their porting works.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.271-281
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• 2007

Real-time support of embedded OS is not optional, but essential in contemporary embedded systems. In order to achieve these system#s real-time property, it is crucial that schedulability analysis for tasks having its property have been accomplished before system execution. Acquiring Worst-Case Execution Time(WCET) of task is a core part of schedulability analysis. Because traditional WCET tools analyze only its estimation of application task(i.e. program), it is not considered that application tasks are affected by scheduling primitives(e.g. scheduler, interrupt service routine, etc.) of OS when it schedules them. In this paper, we design and implement WCET analysis tool which deliberates on scheduling primitives of system using embedded Linux widely used in embedded OSes. This tool can estimate either WCET of normal application programs or corresponding primitives which have an influence on schduling property in embedded Linux kernel. Therefore, precision of estimation about schedulability analysis is improved. We develop this tool as Eclipse#s plug-in to work properly in any platform and support convenient interface or functionality for user.