• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.30-31
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• 2012

본 논문에서는 Android System 핵심 부분을 기존의 System Server 에 Application Server 를 더하여 2개의 서버로 재구성하는 방안을 논의한다. Application Server 는 DalvikVM 과 Application 저장/스케줄링 프로세스로 구성한다. Application Server 가 모든 사용자의 Application 을 저장하고 스케줄링하고 DalvikVM에 할당하여 실행시키도록 한다. 이 방법은 사용자 입장에서는 단순화된 Android System 구조로 인하여 응용의 개발이 용이해지고 응용의 반응도 빠르게 된다. 시스템 입장에서도 구조가 단순해져서 실행 효율이 좋아지고 메모리 사용 효율도 좋아진다.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.5
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• pp.151-154
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• 2014

An energy of applications had consumed through the complexed inter-action with operating systems, run-time environments, compiler, and applications on various mobile devices. In these days, challenged researches are studying to reduce of energy consumptions that uses energy-oriented high-level and low-level compiler techniques on mobile devices. In this paper, we intented to reduce an energy consumption of Java mobile applications that applied a list instruction scheduling for energy dissipation from dalvik bytecode which extracted Android dex files. Through this works, we can construct the optimized power and energy environment on mobile devices with the limited power supply.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.101-102
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• 2012

안드로이드 플랫폼에 적합한 어플리케이션 보급이 급증하면서 안드로이드 가상머신인 달빅(dalvik)의 성능 향상을 위한 연구가 다양하게 시도되고 있다. 전력 공급이 제한적인 모바일 기기에서 효율적인 어플리케이션 실행을 위한 플랫폼의 성능 향상과 더불어 전력 에너지의 최적화된 소비가 중요한 이슈가 되고 있다. 이 논문은 달빅에서 실행되는 dex 파일의 바이트코드를 에너지 소비 중심으로 스케줄링하여 Java 어플리케이션의 전력 에너지 소비를 최적화하고자 하는 시도이다. 에너지 지향적인 스케줄링 기법은 전통적인 리스트-인스트럭션 스케줄링 기법을 기반으로 하였으며 스케줄링 전 후의 실험 결과를 제시하여 이 연구의 효과를 입증한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.1228-1230
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• 2012

안드로이드 플랫폼에 적합한 어플리케이션 보급이 급증하면서 달빅(dalvik)에 관련된 다양한 연구 시도가 진행되고 있다. 특히, Java 클래스 파일로부터 dx에 의해 생성되는 DEX 파일의 구조 및 상세 정보를 시각적으로 분석하고 이를 응용하기 위한 노력은 다양한 성능 향상의 효과를 기대할 수 있다. 이 논문에서는 달빅 가상머신의 실행 파일인 DEX 파일의 구조 및 정보를 세분화하여 시각적으로 쉽게 접근할 수 있는 브라우저를 설계하고 구현한다. 이를 통해서, DEX 파일의 구조 및 정보를 보다 쉽게 접근하고 이용할 수 있으며 디어셈블러(smali/baksmali) 편리하게 사용할 수 있도록 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.177-178
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.141-142
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• 2010

• ETRI Journal
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• v.35 no.2
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• pp.259-269
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• 2013

Android has become the most popular platform for mobile devices. However, Android still has critical performance issues, such as "application not responding" errors and hiccups resulting from garbage collection. Many phone vendors have tried to resolve the problems by characterizing and improving the performance. However, there are few insightful performance analysis tools for the Android-based systems. This paper presents AndroScope, which is a performance analysis tool for both the Android platform (Dalvik virtual machine, core libraries, Android libraries, and even Linux kernels) and its applications. To the best of our knowledge, this is the first tool to collect and analyze performance data from all the software layers of the Android-based systems. AndroScope offers a trace mechanism to collect such deep and wide performance data as hardware performance counters, time, and memory usage. In addition, the tool includes TraceBridge, which is a middleware for the fast handling of mass logs. Moreover, AndroScope offers an integrated graphical user interface with the Android software development kit to display a great volume of the detailed performance data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.309-316
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• 2014

It is easy to reverse engineer an Android app package file(APK) and get its decompiled source code. Therefore, attackers obtains economic benefits by illegally using the decompiled source code, or modifies an app by inserting malware. To address these problems in Android, we propose an APK overwrite scheme that protects apps against illegal modification of themselves by using a new anti-reverse engineering technique. In this paper, the targets are the apps which have been written by any programmer. For a target app (original app), server system (1) makes a copy of a target app, (2) encrypts the target app, (3) creates a stub app by replacing the DEX (Dalvik Executable) of the copied version with our stub DEX, and then (4) distributes the stub app as well as the encrypted target app to users of smartphones. The users downloads both the encrypted target app and the corresponding stub app. Whenever the stub app is executed on smartphones, the stub app and our launcher app decrypt the encrypted target app, overwrite the stub app with the decrypted target one, and executes the decrypted one. Every time the target app ends its execution, the decrypted app is deleted. To verify the feasibility of the proposed scheme, experimentation with several popular apps are carried out. The results of the experiment demonstrate that our scheme is effective for preventing reverse engineering and tampering of Android apps.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.149-150
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• 2010

• Journal of Digital Contents Society
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• v.12 no.4
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• pp.551-557
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• 2011

In this paper, we propose a stack allocation technique of Android Java objects in order to reduce the number of garbage collection which is one of major reason on Android performance degradation when running applications. The proposed technique is to allocate Java objects into stack rather than heap memory. To do so, stacked objects could escape the garbage collection process. We experiment the proposed technique in the latest Android 2.3 version. For the simulation, we take advantage of the well known Java benchmark, Caffeinemark, and our own. The result shows the performance degradation of Dalvik Virtual Machine execution time caused by the stack allocation of Java objects is very slight and the proposed method considerably reduces the frequency of garbage collection. This will increase application performance and give better user interfaces to Android phone users.