• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.347-352
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• 2004

This thesis deals with a task scheduling on a message-passing system. Scheduling and allocation are very important issues since the inappropriate scheduling of tasks cannot exploit the true potential of the system and it can offset the grain from parallelization. It is difficult to apply previous schemes to message-passing system, because previous schemes assume the shared memory system. This thesis proposes an modified priority function and processor selection technique that consider the problems caused by the difference between previous models and message-passing environments. The priority function includes the cumulative communication cost which causes task execution to be delayed. The processor selection technique avoids the situation that a child task is assigned to the same Processor allocated to its parent task that has other unscheduled child tasks. We showed by some simulations that our modified features of task scheduling algorithm can make the better scheduling results than the previous algorithms.

• Journal of Korea Multimedia Society
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• v.9 no.4
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• pp.482-489
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• 2006

How to process event message traffic efficiently is important to collaboration among multiple distributed users, and it is a key research issue in the virtual environment fields. AOI model is one of solutions for this problem; which reduces message traffic by restricting event propagation region into an area in which a user is interested. However, in previous systems, it is difficult to adapt to dynamic environment where changes in the number and movement of participants are frequent. This paper proposes a new event management model, called extended AOI model, which is helpful to improve flexibility and efficiency of traditional models, and is able to extend its functions by introducing multi-layered regions. The proposed model can be applied to DVE and MMORPG as an event filtering model.

• The Journal of the Korea Contents Association
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• v.4 no.3
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• pp.13-19
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• 2004

Because XML is a W3C standard and has characteristics like platform independent, it has a critical role in electronic commerce. Many electronic commerce systems are already using XML. Business rules and procedures should be standardized for efficient B2B electronic commerce. But a lot of companies have its own XML documents instead of standard documents. In this paper an XML message processor is designed. Clients may request services in XML and server returns response in XML in this system. This XML message processor can be applied easily and used efficiently in electronic commerce systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2678-2684
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• 2014

In this paper a new message control method that can reduce server load and network traffic in XMPP/SIP presence service system has been proposed. This presence service system can process both XMPP(Extensible Massaging and Presence Protocol) based presence information and SIP(Session Initiation Protocol) based presence information. A new XMPP stanza architecture with added elements for presence stanza and IQ stanza has been designed, and a new presence information data processing method which can reduce size of SIP notification message and SIP PUBLISH message has been suggested. Furthermore a messages exchanging procedure that can transfer presence information between XMPP domain and SIP domain has been also suggested. The performance of the proposed system has been analysed by simulation.

• The Journal of Korean Association of Computer Education
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• v.9 no.1
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• pp.107-118
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• 2006

Load redistribution algorithm is a critical factor in computer system. In a receiver-initiated load redistribution algorithm, receiver(underloaded processor) continues to send unnecessary request messages for load transfer until a sender(overloaded processor) is found while the system load is light. Therefore, it yields many problems such as low cpu utilization and system throughput because of inefficient inter-processor communications until the receiver receives an accept message from the sender in this environment. This paper presents an approach based on genetic algorithm(GA) for dynamic load redistribution including self-adjustable in heterogeneous distributed systems. In this scheme the processors to which the requests are sent off are determined by the proposed GA to decrease unnecessary request messages.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.238-240
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• 2002

MoIM(Mobile Message Internet Middleware)-Message 시스템은 이러한 메시지 시스템의 요구사항을 만족하는 메시지 시스템으로서 Point-to-Point 및 Publish-Subscribe 방식을 제공하는 시스템이다. 이 시스템의 통신 방법은 RMI(Remote Method Invocation)을 사용한다. 최근의 인터넷 사용자 수가 급증함에 따라서 메시징 서버를 사용하는 동시 클라이언트의 수도 수천에서 수만으로 이를 것으로 예상되어 대규모의 동시 사용자를 지원하는 연결 기술이 필요하다. 이 논문에서는 이러만 대용량의 데이터를 RMI 통신방법을 사용하여 설계 및 구현한 방법을 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.700-707
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• 2000

In this paper, we address vulnerabilities of legacy VOD system and implement secure-VOD system to protect security holes of it. Our secure-VOD system provide user authentication using one-time password, message authentication and encryption/decryption for video server information. To improve security of existing fixed password system, our secure-VOD system use one-time password. Also, our secure-VOD system provides integrity for video server information by generating and verifying message authentication code using HMAC-HAS 160 algorithm. Finally, our secure-VOD system uses RC5 encryption algorithm to guarantee confidentiality for video server information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.899-912
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• 2000

PVM provides users with a single image of high performance parallel computing machine by collecting machines distributed over a network. Low communication overhead is essential to effectively run applications on PVM based platforms. In the original PVM, three times of memory copies are required for a PVM task to send a message to a remote task, which results in performance degradation. We propose a zero-copy model using global shared memory that can be accessed by PVM tasks, PVM daemon, and network interface card(NIC). In the scheme, a task packs data into global shared memory, and notify daemon that the data is ready to be sent, then daemon routes the data to a remote task to which it is sent with no virtual data copy overhead. Experimental result reveals that the message round trip time between two machines is reduced significantly in the proposed zero-copy scheme.

• The KIPS Transactions:PartA
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• v.13A no.6 s.103
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• pp.525-532
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• 2006

Compared with the previous recovery algorithms for causal message logging, Elnozahy's recovery algerian considerably reduces the number of stable storage accesses and enables live processes to execute their computations continuously while performing its recovery procedure. However, if causal message logging is used with asynchronous checkpointing, the state of the system may be inconsistent after having executed this algorithm in case of concurrent failures. In this paper, we show these inconsistent cases and propose a low-cost recovery algorithm for causal message logging to solve the problem. To ensure the system consistency, this algorithm allows the recovery leader to obtain recovery information from not only the live processes, but also the other recovering processes. Also, the proposed algorithm requires no extra message compared with Elnozahy's one and its additional overhead incurred by message piggybacking is significantly low. To demonstrate this, simulation results show that the first only increases about 1.0%$\sim$2.1% of the recovery information collection time compared with the latter.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.729-733
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• 2006

Short message service (SMS) is a Popular mobile data service in cellular networks. One SMS message can carry 50 Korean alphabets. Cellular operators standard and develop multimedia message service (MMS) based on P2P as color phones having multimedia solutions such as MIDI, MP3, JPG, PNG, and MPEG have been developed. MMS can be a key cash flow in the non-voice mobile revenue together with SMS. Copyrights protection of contents in a MMS message can be issued as MMS can be the popular P2P service such as MMS. In this paper, we propose MMS DRM system to protect copyrights of contents in MMS with the minimum change of MMS system. The proposed MMS DRM system protect copyrights of contents using DRM Packager, DRM Server, and DRM Agent and support various use cases to activates MMS in mobile networks.