• The KIPS Transactions:PartA
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• v.16A no.6
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• pp.463-472
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• 2009

Real-time operating systems must have satisfying various conditions such as effective scheduling policies, minimized interrupt delay, resolved priority inversion problems, and its applications to be completed within desired deadline. The real-time operating systems, therefore, should be designed and developed to be optimal for these requirements. MicroC/OS-II, a kind of Real-time operating systems, uses the basic priority inheritance with a mutex to solve priority inversion problems. For the implementation of mutex, the kernel in an operating system should provide supports for numerous tasks with same priority. However, MicroC/OS-II does not provide this support for the numerous tasks of same priority. To solve this problem, MicroC/OS-II cannot but using priority reservation, which leads to the waste of unnecessary resources. In this study, we have dealt with new design a protocol, so called TPSP(Temporary Priority Swap Protocol), by an effective solution for above-mentioned problem, eventually enabling embedded systems with constrained resources environments to run applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.4
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• pp.35-42
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• 2010

This paper reviews the current studies about the current secure OS, security module and SELinux, and suggests Linux access control module that uses the user discriminating authentication, security authority inheritance of subjects and objects, reference monitor and MAC class process and real-time audit trailing using DB. First, during the user authentication process, it distinguishes the access permission IP and separates the superuser(root)'s authority from that of the security manager by making the users input the security level and the protection category. Second, when the subjects have access to the objects through security authority inheritance of subjects and objects, the suggested system carries out the access control by comparing the security information of the subjects with that of the objects. Third, this system implements a Reference Monitor audit on every current events happening in the kernel. As it decides the access permission after checking the current MAC security attributes, it can block any malicious intrusion in advance. Fourth, through the real-time audit trailing system, it detects all activities in the operating system, records them in the database and offers the security manager with the related security audit data in real-time.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.73-82
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• 2007

In recent years, embedded systems have been expanding their application domains from traditional applications (such as defense, robots, and artificial satellites) to portable devices which execute more complicated applications such as cellular phones, digital camcoders, PMPs, and MP3 players. So as to manage restricted hardware resources efficiently and to guarantee both temporal and logical correctness, every embedded system use a real-time operating system (RTOS). Only when the RTOS makes kernel services deterministic in time by specifying how long each service call will take to execute, application programers can write predictable applications. Moreover, so as for an RTOS to be deterministic, its scheduling and context switch overhead should also be predictable. In this paper, we present the complete generalized algorithm to determine the highest priority in the ready list with 22r levels of priorities in a constant time without additional memory overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.295-303
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• 2005

Recently, according to the rapid increase of Web users, various kinds of Web applications have been being developed. Hence, Web QoS(Quality of Service) becomes a critical issue in the Web services, such as e-commerce, Web hosting, etc. Nevertheless, most Web servers currently process various requests from Web users on a FIFO basis, which can not provide differentiated QoS. This paper presents a load balancing method to provide differentiated Web QoS in clustering web server. The first is the kernel-level approach, which is adding a real-time scheduling process to the operating system kernel to maintain the priority of user requests determined by the scheduling process of Web server. The second is the load-balancing approach, which uses IP-level masquerading and tunneling technology to improve reliability and response speed upon user requests. The third is the dynamic load-balancing approach, which uses the parameters related to the MIB-II of SNMP and the parameters related to load of the system such as memory and CPU.

• 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.

• Annual Conference of KIPS
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• 2005.05a
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• pp.1679-1682
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• 2005

최근 SoC를 포함하는 대부분의 임베디드시스템에서는 RTOS가 선택이 아닌 필수적인 구성요소가 됨에 따라 SoC 개발의 초기단계에서부터 RTOS를 도입하는 것이 바람직하다. 하지만, 기존의 범용 RTOS가 제공하는 기능은 대부분 응용 소프트웨어의 개발과 수행을 위한 것으로 SoC 개발 및 검증에는 적합하지 않은 문제점을 가지고 있다. 본 연구에서는 SoC 개발을 위해 운영체제가 만족시켜야할 요구사항을 제시하고, 소프트웨어의 재사용성과 SoC의 검증을 함께 지원하는 VPOS(Verification-Purpose OS)를 개발하였다. VPOS는 초경량의 단순한 계층적 구조(layered structure)를 가지는 RTOS로서 소프트웨어 재사용을 위해 POSIX 표준 API, 유닉스 호환 디바이스 드라이버 인터페이스, HAL 등을 제공한다. 또한 SoC 설계의 검증을 위해 RT 수준의 통합시뮬레이션에 적합한 커널 구조 및 최적화된 코드, 하드웨어 테스트를 위한 쉘 명령어, 응용 소프트웨어의 디버깅을 위한 KREM(kernel resource and event monitoring) 등의 특징을 함께 제공한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.533-543
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• 2003

Recently, according to the rapid increase of Web users, various kinds of Web applications have been being developed. Hence, Web QoS(Quality of Service) becomes a critical issue in the Web services, such as e-commerce, Web hosting, etc. Nevertheless, most Web servers currently process various requests from Web users on a FIFO basis, which can not provide differentiated QoS. This paper presents two approaches to provide differentiated Web QoS. The first is the kernel-level approach, which is adding a real-time scheduling processor to the operating system kernel to maintain the priority of user requests determined by the scheduling processor of Web server. The second is the load-balancing approach, which uses If-level masquerading and tunneling technology to improve reliability and response speed upon user requests.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.810-815
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• 2009

In recent years, embedded systems such as cellular phones, Portable Multimedia Player, intelligent appliance, automobile engine control are reshaping the way people live, work, and play. Thereby, applications for embedded systems become increasingly sophisticated and complicated, such embedded computing platforms must use real-time operating systems (RTOSs) with time determinism. These RTOSs must not only provide predictable services but must also be efficient and small in size and it's kernel services should also be deterministic by specifying how long each service call will take to execute. Having this information allows the application developers to better plan their real-time application software so as not to miss the deadline of each task. In this paper, we present the complete generalized algorithm using multi-dimensional methodology to determine the highest priority in the ready list with 2r levels of priorities for an arbitrary integer number of r.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.67-73
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• 2018

From a software engineering point of view, tracing is a special form of logging that records program execution information. Tracers using dedicated hardware are often used because of the characteristics of tracers that need to generate and decode huge amounts of data in real time. Intel(R) PT uses proprietary hardware to record all information about software execution on each hardware thread. When the software execution is completed, the PT can process the trace data of the software and reconstruct the correct program flow. The hardware trace program can be integrated into the operating system, but in the case of the window system, the integration is not tight due to problems such as the kernel opening. Also, it is possible to trace only a single process and not provide a way to trace multiple process streams. In this paper, we propose a method to extend existing PT trace program to support multi - process stream traceability in Windows environment in order to overcome these disadvantages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1301-1306
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• 2011

RTOS in the embedded system is a powerful tool for the design of multi-tasking. However, previous RTOS has large proportion in the MCU with limited memory. So it is difficult to apply RTOS. In this paper, I removed less frequently used features from the traditional RTOS, and designed lightweight RTOS that schedules and manages the resources with minimal code. I used techniques to obtain user memory using sharing stack, and to reduce the overhead at context. Considering ratio of kernel and applications, the RTOS designed in this paper is available on the MCU with more than 4KB of program memory.