• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.109-110
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• 2017

모바일 디바이스들의 사용 보편화와 대용량화로 인해 모바일 환경에 적합한 데이터베이스 엔진들이 최근 다양한 목적으로 모바일 기기에 많이 도입되고 있다. 이 엔진들은 대부분 오픈소스 프로그램들이며 범용 데이터베이스에 비해 가볍고 속도가 빠른 장점을 지녀 향후 발전 가능성이 커보인다. 이 논문에서는 안드로이드 등의 모바일 환경에서 대표적으로 활용되고 있는 SQLite 데이터베이스와 Realm 데이터베이스를 선정하여 검색 성능 및 특성을 파악하고 비교하기 위한 성능 실험을 설계한다.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.29-34
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• 2017

Over the past several decades, embedded system and flight control computer technologies have been evolved to meet the diverse needs of the mobile device market. Current embedded systems are at the heart of technologies that can take advantage of small-sized specialized hardware while still providing high-efficiency performance at low cost. One of these key technologies is multiple memory banks. For example, a dual memory bank can provide two times more memory bandwidth in the same memory space. This benefit take lower cost to provide the same bandwidth. However, there is still few software technologies to support the efficient use of multiple memory banks. In this study, we present a technique to efficiently exploit multiple memory banks by software support. Specifically, our technique use an interference graph to optimally allocate data to different memory banks by an optimizing compiler. As a result, the execution time can be improved upto 7% with the proposed technique.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.370-372
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• 2006

임베디드 리눅스 운영체제는 전형적인 임베디드 시스템 중의 하나인 휴대폰 환경에도 적용될 수 있다. 실제로 최근 휴대폰 제조사들이 휴대폰에 리눅스를 채택하기 시작하면서 리눅스 기반의 운영체제를 탐재한 휴대폰이 다수 개발되어 휴대폰 시장에서 꾸준한 성장 추세를 이어가고 있다. 임베디드 리눅스를 휴대폰 환경에 적용하기 위해서는 몇 가지 기술적인 요구사항들이 고려되어야 하며, 대표적으로 리눅스 시스템 크기에 대한 경량화가 필요하다. 본 논문에서는 임베디드 리눅스를 휴대폰 환경에 적용하기 위한 구체적인 경량화 기법들을 제시하고 각 기법을 휴대폰 리눅스 플랫폼 환경에 적용하여 커널과 루트 파일 시스템 각각의 ROM, RAM 사용량 측면에서 그 효과를 검증해 본다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.175-177
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• 2006

휴대폰에 임베디드 리눅스를 탑재하고자 할 경우 전력소모, 경량화, 빠른 부팅, 실시간, 보안 등과 관련한 추가고려사항이 발생한다. 본 연구에서는 휴대폰용 임베디드 리눅스의 커널 부팅시간을 단축시키기 위한 구체적인 방법을 제시하고 실제적인 적용을 통하여 그 성능을 평가한다. 측정된 데이터를 바탕으로 커널내부에서 가장 많은 시간을 소요하는 함수들을 찾아내고 확인된 함수들에 대해서 초기화 지연회피, 불필요한 장치 드라이버 제거, 불필요한 커널 메시지 미출력 등의 기법들을 각각 적용한다. 제안된 기법을 모두 적용할 경우에 기존 커널 부팅시간을 50%정도 단축시킬 수 있었다.

• Journal of the Korea Society of Computer and Information
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• v.21 no.9
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• pp.139-147
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• 2016

In recent, android application developments have been done widely that intensify smart phone utilization. In this paper, we propose a curriculum that undergraduate students can improve their mobile programming abilities as well as integrate experiences of application development based on android. And also a series of practices to advance their sense of accomplishment are added by offering an opportunity to carry out a real project to use a variety of sensors embedded in smart phone during the course of study. The project is composed of a series of modules for implementing a trekking App that helpful to people who enjoy spending time in outdoors through their favorite activities such as trekking, cycling, and climbing with their own smart phones. Through practical curriculum operation and project implementation, we show that the proposed curriculum is appropriate to a mobile programming education that combine learning and practice.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.238-248
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• 2007

As the demand of employing various PC software on mobile embedded devices which have limited storages has been increased, software streaming services are needed. However it takes too much time to launch software on them because it is transferred through wireless networks. To address this problem, prefetch algorithms are needed. We examined 'Last successor (LS)' algorithm and PPM-based prefetch algorithm as prefetch algorithms for software streaming services. We present 'Probability-base Multi Successor (PMS)' algorithm which is contrived through analyzing evaluations of previous algorithms and characteristics of software streaming services. While LS has one successor per each block, PMS has N successors based on probability which is calculated by PPM-based prefetch algorithm. The hit rate of PMS is similar to that of PPM-base prefetch algorithm and the space overhead is similar to that of LS. We can get good efficiency at the point of memory usage when PMS is applied to software streaming services.

• 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 Korea Multimedia Society
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• v.8 no.9
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• pp.1282-1291
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• 2005

This paper presents the EVM(Embedded Virtual Machine) which enables the execution of dynamic applications loaded in the embedded systems such as Mobile Devices(mobile phone, PDA), Set-Top Box, and Digital TV using downloading techniques. To accomplish this goal, we defined a SIL-(Standard Intermediate Language) code, and implemented a Bytecode-to-SIL translator which enables the execution of programs written in java language in the EVM platform without JVM, and a MSIL--to-SIL- translator which enables for programs written in .NET language to be executed in the EVM platform without .NET platform. Also, we developed a EFF(Executable File Format) builder as an assembler which translates SIL codes into an executable file, *.evm, and implemented the EVM which reads the *.evm file and executes it. The virtual machine for embedded systems developed in this paper is the software technologies that enable the execution of applications or contents without changes to when the platforms change. In fact, the virtual machine suggested here is not only usable as a standard model for existing virtual machines but also aid in more efficient execution of applications loaded in the embedded systems such as Mobile Devices, Digital TV, and Set-Top Box.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.5
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• pp.355-359
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• 2009

When an unexpected software exception arises, we programmers are to analyze what causes it. Precisely speaking, we need to analyze the cause and property of the unexpected exception. But if exceptions arise irregularly from unknown causes, it is even more difficult for us to handle them, especially in embedded system like mobile phone software development. In this paper, we propose a debugger-friendly analyzing method for exceptions using aspect oriented programming technique. What we need to know upon arising exceptions is the function call history in order to identify the reason for the exceptions. Since programmers used to spend their debugging time on unidentified exceptions, which arise irregularly our method would greatly improve the embedded software development productivity.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.532-535
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• 2004

Architecture generation is the first step in the design of software systems. Most of the qualities that the final software system possesses are usually decided at the architecture development stage itself. Thus, if the final system should be usable, testable, secure, high performance, mobile and adaptable, then these qualities or non­functional requirements should be engineered into the architecture itself. In particular, adaptability is emerging as an important attribute required by almost all software systems. The machinery and tools in the remote site surveillance and connects intelligence information machinery and tools at Internet. We need the server which uses different embedded operating system to become private use. With the progress of information-oriented society, many device with advanced technologies invented by many companies. However, the current firmware technologies have many problems to meet such high level of new technologies. In this paper, we have successfully ported linux on an embedded system, which is based on intel StrongARM SA-1 1 10 processor, then written several network modules for internet-based network devices.