• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.379-388
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• 2005

Image steganography Is a secret communication scheme to transmit a secret message, which is embedded into an image. The original image and the embedded image are called the cover image and the stego image, respectively. In other words, a sender embeds a secret message into a cover image and transmits a stego image to a receiver, while the receiver takes the stego image, extracts the message from it, and reads the message. General requirements for steganography are great capacity of secret messages, imperceptibility of stego images, and confidentiality between a sender and a receiver. In this paper, we propose a method for being satisfied with three requirements. In order to hide a secret message into a cover image safely, we use a difference value of two consecutive pixels and a secret quantization range. The former is used for the imperceptibility and the latter for the confidentiality. Furthermore, the number of insertion bits is changed according to the difference value for the imperceptibility. Through experiments, we have shown that our method is more good quality of stego images than many other related methods and increases the amount o( message insertion by performing dual insertion processing for some pixels.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.253-255
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• 2003

We address an integrated multimedia framework based on a software agent platform for context-aware multimedia computing. We adopt the FIPA (Foundation for Intelligent Physical Agents) platform which provides agent communications and management mechanisms. In order to express context information, we use MPEG-21 metadata for describing user characteristics and usage environment. We encapsulate such context information as a FIPA message to be delivered between agents. Based on context information, appropriate multimedia content delivery becomes possible. We present our system implementation with a use case scenario and show that our proposed framework is effective for context-aware multimedia computing so that personalization of multimedia consumption can be possible.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3139-3149
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• 1997

E-mail system has been widely used for information transmission. As multimedia technologies are developed, many Internet services support multimedia. E-mail system only transmits 7bit ASCII data using simple mail transfer protocol(SMTP) specified in RFC 821. E-mail system can't support the authoring and the transmission of multimedia data. In this study multimedia mail authoring system has been designed and implemented in order to provide message integration. Multimedia messages can be authored and transformed into text types with this system. Transformed messages are transmitted from sender's mail transfer agent (MTA) to receiver's MTA by means of SMTP. Messages can be authored in hypertext markup language (HTML) including text, image, audio and video. This system provides integrated messages which consist or various media. BASE64 Encoding method is used in order to transform multimedia messages into text types. Received mails are managed by multimedia user agent (MUA) which is proposed in this study. Convenience for user is improved in this system.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.343-345
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• 2000

본 논문에서는 SMS(Short Message Service)로부터 발전하여 WAP(Wireless Application Prorocol)을 이용한 픽처 메시지 및 간단한 에니메이션 서비스의 단계를 지나 데이터의 포맷이나 형식을 가리지 않는 멀티미디어 데이터 정보를 메시징할 수 있는 서비스 센터의 구현에 관한 내용을 기술한다. MMS(Multimedia Messaging Service)기술은 IS-95C 및 IMT-2000에서 통신 속도가 빨라짐에 따라서 발생할 수 있는 여러 서비스 중의 하나로 기존의 메시징 시스템의 한계를 극복하고 보다 크고 다양한 정보를 전달할 수 있는 인프라 역할을 하면서 더욱 새로운 서비스를 만들어 낼 수 있을 것이다.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.883-892
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• 2009

SOAP using WSDL(Web Service Definition Language) was proposed for effective integration of distributed objects. But the SOAP message and WSDL document automatically generated from development tool are fully dependent on the development environments. So the dependency of SOAP messages and WSDL documents for objects to the development environment is still a big problem to be solved for the integration of heterogeneous distributed objects. In order to support integration of heterogeneous distributed object, we implemented SOAP Bridge called WBSB(WSDL Based SOAP Bridge). As service request message for a particular service object is translated into appropriate SOAP message for the selected service object by WBSB using WSDL repository, a client can use service object without considering the development environment of the service object.

• Journal of Korea Game Society
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• v.9 no.2
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• pp.105-113
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• 2009

The most important service of the online game is the stability. However, in online games, the increase in the number of users burdens the server as thousands of users connect to the server at the same time. While various techniques to reduce the load on the server are studied, the study is limited only to the server part like an improvement of server algorithms. In this paper, a program to handle the largest load of the server, the message synchronization of both the server and client, is designed and implemented.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.94-101
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• 2007

Partial dominant pruning(PDP) is regarded as the most practical scheme, reducing redundant messages arisen in broadcasting over ad hoc networks, in such a way that only part of nodes are allowed to forward the received broadcast message. In this paper we propose an extend PDP version called DPDP(directional PDP) such that it reduces not only the number of selected forward nodes, but also the number of antenna elements deployed by the forward nodes. It turns out through simulation that as the number of antenna elements increases, the number of selected forward nodes by DPDP slightly outnumbers that obtained using PDP but both the number of antenna elements deployed by the forward nodes and the redundancy ratio of the received message per node always outperform respectively those given by PDP.

• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.23-30
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• 2005

Causal order of message delivery algorithm ensures that every transmitted message is delivered in causal order. It should be noted that control information should be transmitted with each message in order to enforce causal order. Hence, it is important to reduce this communication overhead because the impact of the overhead increases proportionally with the number of related processes. In this paper we propose and evaluate effective a ${\Delta}-causal$ order algorithm for multimedia data which have real-time property. To reduce transmission overhead, proposed algorithm eliminates redundant information as early as possible which is not explicitly required for preserving causal order. Average communication overhead of our algorithm is much smaller than other existing algorithms.

• Journal of Korea Multimedia Society
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• v.11 no.11
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• pp.1536-1546
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• 2008

RSVP-capable router supporting guaranteed services on the internet generally uses a packet scheduler based on the Weighted Fair Queuing (WFQ) algorithm to secure required qualities of traffic flows. A RSVP-capable router based on the LOFQ (Latency optimized fair queuing) algorithm had been proposed to improve the performance of the WFQ-based RSVP-router, but it required not only the RESV message to be expanded but also its performance could be evaluated only through simulation. This paper proposed a LOFQ based RSVP-capable router using the conventional RESV message and developed an algorithm to analyze the performance of the LOFQ based RSVP-capable routers. The performance evaluation using the developed algorithm showed that in terms of performance improvement the proposed router is inferior to the one using the expanded RESV message under a small packet size, but on the range of a large packet size both routers provide the same improvement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.3
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• pp.251-265
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• 2009

VoIP service is the transmission of voice data using SIP protocol on an IP-based network. The SIP protocol has many advantages, such as providing IP-based voice communication and multimedia service with low communication cost. Therefore, the SIP protocol disseminated quickly. However, SIP protocol exposes new forms of vulnerabilities to malicious attacks, such as message flooding attack. It also incurs threats from many existing vulnerabilities as occurs for IP-based protocol. In this paper, we propose a new virtual proxy to cooperate with the existing Proxy Server to provide state monitoring and detect SIP message flooding attack with IP/MAC authentication. Based on a proposed virtual proxy, the proposed system enhances SIP attack detection performance with minimal latency of SIP packet transmission.