• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1002-1005
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• 2015

Mobile operating systems have been typically classified into Apple and Android. Samsung showed its own new mobile OS developing Tizen based on Linux kernel. Mobile operating system has developed a technology using low-power by itself because of the limitation of capacity of battery, a feature of mobile. Samsung Tizen OS has a low-power technology called Power Manager controling LCD states as users'inputs or time-out events occur. However, if users'input occurs frequently, energy consumption jumped before-and-after users'input because CPU clock is increased rapidly due to overhead increase for frequent LCD state changes. This paper proposes a mechanism to reduce the overhead for LCD state changes, when user's input is frequent, by adding a new state to the Power Manager the current Tizen OS is using. We have implemented the proposed mechanism at Tizen phone kernel layer in this paper and experimented the mechanism according to users' LCD touch inputs. The experiment shows that it is possible to decrease energy by reducing the CPU clock increase according to the frequent user's inputs.

• 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.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.63-72
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• 2005

This paper describes a new approach for the operating system level power management to reduce the energy consumed in the IO devices in a robot platform, which provides various functions such as navigation, multimedia application, and wireless communication. The policy proposed in the paper, which was named the Energy-Aware Job Schedule (EAJS), rearranges the jobs scattered so that the idle periods of the devices are clustered into a time period and the devices are shut down during their idle period. The EAJS selects a schedule that consumes the minimum energyamong the schedules that satisfy the buffer and time constraints. Note that the burst job execution needs a larger memory buffer and causes a longer time delay from generating the job request until to finishing it. A prototype of the EAJS is implemented on the Linux kernel that manages the robot system. The experiment results show that a maximum $44\%$ power saving on a DSP and a wireless LAN card can be obtained with the EAJS.

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.45-53
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• 2011

According to the necessity of measuring equipments for advanced military systems, real-time characteristics such as time determinism and execution accuracy pursuing low-latencies have become very important. With this reason, the market demand for real-time features in the general purpose operating system such as Linux has been enlarging. To meet these requirements, RTLinux and RTAI has been developed as dual-kernels based on Linux. However, developers should use assembler languages to facilitate real-time in RT-Linux, it is very difficult to deal with it. RTAI has disadvantage that it only provides soft real-time. To solve these problems, RTiK-Linux was developed. In this paper, we propose a new dual-kernel with hard real-time capabilities in Linux, called RTiK-Linux(Real-Time implemented Kernel for Linux). We first introduce related researches and then describe the design methodologies to guarantee the resolution which almost accords with the timer settings. Finally, we present the results of experimental measurements and analyze them in order to validate and evaluate the proposed RTiK-Linux.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.194-201
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• 2007

As the performance of the mobile terminal becomes higher, the power consumption gradually increases. As a result, power management is one of the most important issues in mobile system with battery. In this paper, we describe an DPM(Dynamic Power Management) using DVS(Dynamic Power Management) as a power management mechanism in Qplus operating system. DVS generally considers a specific device such as CPU, whereas we consider the relations with other hardware components as well as each component. We specially focus on the relation between CPU, memory and LCD devices. We also designs a kernel monitor to collect information to decide the policy for power management. According to the experimental results, the proposed method enables to save much power.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.1
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• pp.43-50
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• 2017

Use-After-Free security problem is rapidly growing in popularity, especially for attacking web browser, operating system kernel, local software. This security weakness is difficult to detect by conventional methods. And if local system or software has this security weakness, it cause internal security problem. In this paper, we study ways to remove this security weakness in software development by summarize the cause of the Use-After-Free security weakness and suggest ways to remove them.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.3
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• pp.145-153
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• 2013

Virtualization technology has been applied in IA-32 based server or desktop systems. Recently it has been applied in ARM based mobile systems. Virtualization technology provides many useful features that are not possible in operating system level such as isolation, interposition, encapsulation and portability. In this research, we implement an ARM based VMM(Virtual Machine Monitor) by using the following techniques. First, we use "emulation" to virtualize the processor. Second, we use "shadow page tables" to virtualize the memory. Finally, we use a simple "pass-through I/O" to virtualize the device. Currently the VMM runs ARM Linux kernel 3.4.4 on a BeagleBoard-xM, and we evaluated the performance of the VMM using lmbench and dhrystone. The result of the evaluation shows that our VMM is slower than Xen on ARM that is implemented using paravirtualization but has good performance among the VMMs using full-virtualization.

• Annual Conference of KIPS
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• 2002.11b
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• pp.1031-1034
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• 2002

본 논문에서는 커널수준의 침입탐지를 위한 동적 침입탐지 규칙 변경 기법을 제안한다. 제안하는 기법은 침입탐지 규칙은 규칙타입 프로토콜 타입, 패킷 헤더와 패킷 페이로드에 대한 검사를 수행하기 위한 규칙들로 세분화하여 LVR로 표현하고 이들 LVR이 계층적으로 구성된 IDRL로 관리한다. 침입탐지는 IDRL을 이용하여 수행하며, 규칙에 대한 변경은 변경된 규칙에 대한 LVR을 구성하고 LV를 이용한 포인터 변경을 이용하여 IDRL에 반영하는 방법이다. 제안하는 기법은 IDRL을 이용한 침입탐지와 탐지규칙의 변경을 IDRL에 최소한의 비용으로 수행하고, LVR을 이용하여 침입탐지 규칙을 디스크와 메모리에 동일한 형태로 저장 및 관리하여 탐지규칙 초기화 비용과 변경 비용을 최소화할 수 있다. 이를 통하여 보다 안전한 커널 수준에서의 네트워크 보안을 위한 효율적인 동적 침입탐지 규칙 변경을 지원할 수 있다는 장점을 가진다.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.205-209
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• 1998

A synthesis of fuzzy variable structure control is proposed to design a high-angle-of-attack flight system for a modification version of the F-18 aircraft. The knowledge of the proportional, integral, and derivative control is combined into the fuzzy control that addresses both the highly nonlinear aerodynamic characteristics of elevators and the control limit of thrust vectoring nozzles. A simple gain scheduling method with multi-layered fuzzy rules is adopted to obtain an appropriate blend of elevator and thrust vectoring commands in the wide operating range. Improving the computational efficiency, an accelerated kernel for on-line fuzzy reasoning is also proposed. The resulting control system achieves the good flying quantities during a high-angle-of- attack excursion. Thus the fuzzy logic can afford the control engineer a flexible means of deriving effective control laws in the nonlinear flight regime.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.131-136
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• 2021

EtherCAT is an Ethernet-based fieldbus system standardized in IEC 61158 and SEMI, and widely used in the fields of factory automation, semiconductor equipment and robotics. In this paper, a real-time EtherCAT master is implemented on Linux operating systems and its performances are evaluated. To enhance the real-time capability of mainline Linux kernel, Xenomai is applied as a real-time framework and an open source EtherCAT master stack, Simple Open EtherCAT Master (SOEM), is installed on it. Unlike other studies, the real-time performance of the EtherCAT master is evaluated at the output of the network interface card, so that the evaluation results include all possible effects from the EtherCAT master system. The implemented EtherCAT master can send and receive packets up to 20KHz control frequency with low jitter, even in stressed condition.