• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1080-1097
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• 2010

Well organized and easy usable Grid management system is very important for executing various Grid applications and managing Grid computing environment. Moreover, information system which can support Grid management system by providing various Grid environment related information is also one of the most interesting issue in the Grid middleware system area. Effective cooperation between Grid management system and information system can make a novel Grid middleware system. Especially, service oriented architecture based Grid management system is flexible and extensible for providing various type of Grid services. Also, information system based on data mining process which comprises various different kinds of domains such as users, resources and applications can make Grid management system more precise and efficient. In this paper, we propose semantic Grid middleware system which is a combination of Grid management system and semantic information system.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.141-148
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• 2005

Nowadays, it is possible to access sharing data from unauthorized People. Access control prevents unauthorized access to computing resource, information resources, and communication resources. It is very important to defend the critical system resources from the unauthorized. The importance of this study is to develop Protection Profile for Mandatory Access Control (MAC) that satisfies TCSEC assurance level B2. protection profile for MAC will help developers to use reference for the development of requirements and formulating security specification.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.2
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• pp.1-9
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• 2010

The increasing popularity of mobile devices, such as cellular phones, smart phones, and PDAs, has fostered the need to recommend more effective information in ubiquitous environments. We propose the recommendation method for mobile contents service using contexts and prefetching in ubiquitous environment. The proposed method enables to find some relevant information to specific user's contexts and computing system contexts. The prefetching has been applied to recommend to user more effectively. Our proposed method makes more effective information recommendation. The proposed method is conceptually comprised of three main tasks. The first task is to build a prefetching zone based on user's current contexts. The second task is to extract candidate information for each user's contexts. The final task is prefetch the information considering mobile device's resource. We describe a new recommendation.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.94-96
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• 2003

고속 네트워크의 등장으로 관리 영역을 초월한 계산 자원의 공유가 가능하게 되었고, 그리드 컴퓨팅이 등장하게 되었다. 그리드 환경에 포함된 각 자원들은 이질적이기 때문에 고성능을 얻기 위해서는 효과적인 자원 발견 및 자원 선택이 중요하다. 본 논문에서는 그리드 컴퓨팅에서 다양하고 이질적인 자원들을 각 응용프로그램에서 효율적으로 이용할 수 있도록, 각 참여 노드들에게 순위를 부여하고 각 작업(Task)에 적절한 자원을 할당하여 전반적인 시스템 성능을 극대화시키는 메커니즘을 제안하였다. 각 노드의 순위는 처음 각 노드별 자원의 시스템 사양을 토대로 그룹화하여 작업을 배분하고 각 노드들이 작업을 마친 후 반환 값의 정확도와 응답시간과 같은 동적 요소를 고려하여 참여자의 순위를 부여하였고, 이러한 순위에 따른 작업 재분배 메커니즘은 전체적인 시스템 성능을 향상시키고 정확도를 높인다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.808-810
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• 2004

유비쿼터스 컹퓨팅 환경에서 모바일 디바이스는 Service Controller의 역할을 수행한다. 그러나 모바일 디바이스를 이용하여 원격지 리소스에 접근하는 것은 제약이 따른다. Desktop에서 흔히 쓰이는 FTP와 같은 원격지 접속 기술은 모바일 디바이스에서는 사용 할 수 없다. 또 다른 방안으로 모바일 디바이스에서 Java Application을 이용하여 원격지 컴퓨터에 접속하는 방법이 있다. 그러나 이 또한 Java Security 문제를 해결해야 한다. 모바일 디바이스에서의 Java Security 문제는 그 응용 범위나 필요성에 비해 아직까지 구현 모델은 없다. 따라서 본 논문에서는 Desktop상에서 구현하는 Java Security 접근 방법 모델을 이용하여 모바일 디바이스에서 웹 브라우저를 통해 Java Application으로 원격지 컴퓨터에 접근하는 방법을 구현한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.82-84
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• 2004

Java's performance is sometimes not acceptable due to interpretation overhead by the Java Virtual Machine (JVM). In this paper, we present a compiler structure of Java-to-C translator for high performance on resource limited environment like mobile devices. Our compiler framework translates Java into C codes to preserve Java's programming semantics such as inheritance, method overloading, virtual method invocation, and so on. Also our compiler fully supports Connected Limited Device Configuration (CLDC) 1.0 API's. We show that our compiler improves the speedup by up to eleven times more than JVM-only execution in measured benchmarks.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.322-325
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• 2000

In a batch scheduling policy being different from real video system, the requests are not served immediately due to grouping user's requests upon every scheduling points. Such waiting delays by inefficient managements makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an adaptive batch scheduling scheme which reduces the average waiting time of user’s requests and reduces the starvation problem for requesters of less popular movies. The proposed scheme selects dynamically multiple videos in given intervals based on the service patterns which reflect the popularity distribution and resource utilizations. Experimental simulation shows that proposed scheme improves about 20-30 percent of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• ETRI Journal
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• v.37 no.5
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• pp.845-855
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• 2015

To enable the coexistence of Licensed Assisted Access (LAA) and Wi-Fi in 5 GHz unlicensed bands, a new channel access mechanism is proposed. Accounting for the fairness between LAA and Wi-Fi, the proposed mechanism finds the optimal transmission time ratio by adaptively adjusting the transmission durations for LAA and Wi-Fi. In addition, we propose a new analytical model for the distributed coordination function of IEEE 802.11 through some modifications of conventional analytical models for saturation and non-saturation loads. By computing the activity ratio of Wi-Fi, the proposed analytical model is able to control the time ratio between LAA and Wi-Fi, which is required for practical implementation of the proposed access mechanism. Through numerical simulations, the proposed channel access mechanism is compared with conventional methods in terms of throughput and utility.

• The Journal of Natural Sciences
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• v.7
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• pp.115-120
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• 1995

Imprecise computation has been suggested as a promising model of real-time computing in order to deal with timing constraints imposed by the environment. However, the theoretical foundation of the technique has not been fully explored. To address this, a decision-theoretic foundation of imprecise computation is proposed. The main benefit of such a treatment is that it enables the qualitative assumptions underlying imprecise computation techniques to be explicitly stated in a formal way. The theoretical foundation laid out in this paper, hence, will not only enable the justification of using imprecise computation techniques for a real-time application, but will also facilitate the development of extended techniques for more complexs real-time systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.2
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• pp.99-105
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• 2007

MANET(Mobile Ad-hoc network) have recently attracted a lot of attention in the research community as well as in industry. Although the previous research mainly focused on various of MANET in routing, we consider, in this paper, how to efficiently support applications such as variable geocasting basd on MANET. The goal of a geocasting protocol is deliver data packet to a group of nodes that are located within a specified geocasting region. Previous research that support geocast service in mobilie computing based on MANET have the non-optimization problem of data delivery path, overhead by frequent reconstruction of the geocast tree, and service disruption problem. In this paper, we propose the mobility pattern based geocast technique using variable service range according to the mobility of destination node and resource reservation to solve this problem. The experimental results show that our proposed mechanism has improved performance of Accessibility & Network Overhead than previous research.