• Journal of Computing Science and Engineering
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• v.6 no.1
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• pp.26-38
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• 2012

Java has been increasingly used in programming for real-time systems. However, some of Java's features such as automatic memory management and dynamic compilation are harmful to time predictability. If these problems are not solved properly then it can fundamentally limit the usage of Java for real-time systems, especially for hard real-time systems that require very high time predictability. In this paper, we propose to exploit multicore computing in order to reduce the timing unpredictability that is caused by dynamic compilation and adaptive optimization. Our goal is to retain high performance comparable to that of traditional dynamic compilation, while at the same time, obtain better time predictability for Java virtual machine (JVM). We have studied pre-compilation techniques to utilize another core more efficiently, preoptimization on another core (PoAC) scheme to replace the adaptive optimization system (AOS) in Jikes JVM and the counter based optimization (CBO). Our evaluation reveals that the proposed approaches are able to attain high performance while greatly reducing the variation of the execution time for Java applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1145-1153
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• 2013

Android mobile platform copy the class files of all applications installed in android platform and keep them into one directory. But to add the service library into a platform, Android must generate a new binary image of platform and replace the platform because android refer the libraries using the memory-mapped file method in a directory. And this memory-mapped file reference method waste the storage space of mobile device because that directory include the duplicated libraries if the libraries refered by application are duplicated, Therefore a dynamic reconfiguration method on android mobile platform is needed to manage the service libraries of application executed on android platform and support the version management and function addition/modification. In this paper, we propose the platform dynamic reconfiguration method to add dynmically the service libraries on android platform.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.443-451
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• 2005

Stateful inspection devices must maintain flow information. These devices create the flow information also for network attack packets, and it can fatally inflate the dynamic memory allocation on stateful inspection devices under network attacks. The memory inflation leads to memory overflow and subsequent performance degradation. In this paper, we present a guideline to set the flow entry timeout for a stateful inspection device to remove harmful embryonic entries created by network attacks. Considering Transmission Control Protocol (TCP) if utilized by most of these attacks as well as legitimate traffic, we propose a parsimonious memory management guideline based on the design of the TCP and the analysis of real-life Internet traces. In particular, we demonstrate that for all practical purposes one should not reserve memory for an embryonic TCP connection with more than (R+T) seconds of inactivity where R=0, 3, 9 and $1\leqq{T}\leqq{2}$ depending on the load level.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.1
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• pp.97-106
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• 2016

3D virual reality technique develop rapidly such as parts of education, health, national defense, etc. This paper implements an education contents utilizing 3D virtual reality based on HMD. In this paper, contents make up Changdeokgung Palace using to 3Dmax and Unity program, it shows on implemented Helmet Mounted Display. HMD obtain dynamic image from the target source of smart phone. Also, contents consist of service senerio through divided palace position and King's a day's journey especially. Above all, this paper indicate improving performance according to reduced cybersickness and immersion enlargement. And memory capacity reduced by various technique such that file type, compressed file, minimized resource. Proposed technique can obtain dynamic 3D image by HMD implementation at real time basis so that it is possible to use simultaneously multi-source. From the various and practical experiment, it is confirm that proposed 3D VR education system is useful for experience of virtual reality practically.

• Proceedings of the KSRS Conference
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• v.2
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• pp.725-727
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• 2006

The development of GIS and Location-Based Services requires a high-level database that will be able to allow real-time access to moving objects for spatial and temporal operations. MODB.MM is able to meet these requirements quite adequately, providing operations with the abilities of acquiring, storing, and querying large-scale moving objects. It enables a dynamic and diverse query mechanism, including searches by region, trajectory, and temporal location of a large number of moving objects that may change their locations with time variation. Furthermore, MODB.MM is designed to allow for performance upon main memory and the system supports the migration on out-of-date data from main memory to disk. We define the particular query for truncation of moving objects data and design two migration methods so as to operate the main memory moving objects database system and file-based location storage system with.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.1-10
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• 2010

As processor platforms are continuously moving toward wireless mobile systems, embedded mobile processors are expected to perform more and more powerful, and therefore the development of an efficient power management algorithm for these battery-operated mobile and handheld systems has become a critical challenge. It is well known that a memory system is a main performance limiter in the processor point of view. Although many DVFS studies have been considered for the efficient utilization of limited battery resources, recent works do not explicitly show the interaction between the processor and the memory. In this research, to properly reflect short/long-term memory access patterns of the embedded workloads in wireless mobile processors, we propose a memory buffer utilization as a new index of DVFS level prediction. The simulation results show that our solution provides 5.86% energy saving compared to the existing DVFS policy in case of memory intensive applications, and it provides 3.60% energy saving on average.

• Journal of Digital Contents Society
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• v.12 no.2
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• pp.141-150
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• 2011

Recently the Solid State Drive (SSD) is widely used for storage system of various mobile devices. In this case, existing buffer replacement algorithms based on the hard disk do not consider characteristics of flash memory, so it caused performance degradation of the system. This paper proposes a novel buffer replacement policy called ABM (Asymmetric Buffer Management) policy. ABM policy separates read and write buffer space and applies different replacement unit and replacement algorithm for each buffer. In addition, write buffer delay scheme and dynamic size adaptation algorithm is applied for better performance. ABM outperforms other replacement policies, especially ABM-LRU-CLC shows 32% better performance than normal LRU policy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.878-884
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• 2013

Recent C ++ developers take advantage of the many advantages in memory management in the development of reference counting smart pointer. However, these have a problem more than the normal pointer. In this paper, we not only complement these by reference counting smart pointer which pointing a large dynamic object to perform a delete operation to improve performance by creating a thread for the delete operation but also Generalize all data types, we propose a convenient way to operate.

• Journal of the Korea Society for Simulation
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• v.1 no.1
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• pp.87-102
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• 1992

This paper presents the development of event-driven system level simulation tool SMPLE(Smpl Extende, an extention fo smpl) and its application to the performance analysis of multiprocessor computer systems. Because of its data structure, it is very difficult to change, expand or add new functions to simulation language smpl implemented by MacDougall. In SMPLE, we change data structure with structure and pointer, add new functions, and enable dynamic memory management. Using new data structure, facilities, and functions added in SMPLE, we simulate job processing of a shared bus multiprocessor system with autonomous hierarchical I/O subsystem. We set system performance contribution of subsystems and units. The impact of disk I/O on system performance is evaluated under vairous conditions of number of processors, processing power, memory access time and disk seek time.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.505-508
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• 2013

스마트폰 응용 프로그램의 메모리 관리는 응용 프로그램의 속도와 안정성 측면에서 중요하게 다루어진다. 응용 프로그램에서 다루는 요소 중 이미지는 메모리 사용량의 많은 부분을 차지하며, 메모리의 여유 공간 내에서 이미지가 사용될 수 있도록 관리되어야 한다. 그러나 이미지의 해상도가 커지거나 다루게 되는 이미지의 개수가 늘어날 수록 이미지 객체의 관리의 어려움도 늘어나게 된다. 이미지 객체가 메모리 공간이 부족한 시점에서 메모리에 적재될 경우 응용 프로그램은 성능이 저하되거나 강제 종료될 수 있어 응용 프로그램의 사용성과 안정성이 낮아지게 된다. 본 논문에서는 안드로이드의 응용 프로그램에서 사용되는 이미지가 메모리의 많은 공간을 차지할 때, 안정적인 응용 프로그램 구동 환경을 제공해주는 동적 메모리 관리 기법을 적용하여 OOM(Out of Memory) 오류가 발생하는 문제를 해결하고자 한다.