• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.685-694
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• 2003

Recently as the mobile computing is burgeoning, multimedia services have become very popular. Multimedia services require large data volume and have to send the same data to several users. In order to provide efficient multimedia services that have those characteristic to mobile users, efficient multicast technique to support host mobility is required. Previous research that support multicast services in mobile computing based on Mobile IP have the non-optimization problem of data delivery path, overhead by frequent reconstruction of the multicast tree, and service disruption problem. In this paper, we propose the mobility pattern based multicast technique using variable service range according to the mobility of mobile hosts and resource reservation to solve this problems. The experimental results show that our proposed mechanism has improved performance than previous research.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.245-249
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• 2000

종래의 출입국 관리자는 여권을 재시하면 여권을 육안으로 검색하고 수작업으로 정보를 입력하여 여권 데이터베이스와 대비하는 것이었다. 본 논문에서는 이러한 단점을 보완하고 자동적으로 인증하기 위한 영상 처리와 문자 인식을 통한 여권 인증 시스템에 관한 연구이다. 여권에는 사용자에 대한 많은 정보들이 있다. 이러한 사항을 이용하여 여권에서 추출할 수 있는 문자 정보들에 대해 개선된 ARTI알고리즘을 적용하여 학습하고 자동적으로 인식하도록 하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.352-360
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• 2002

본 논문에서는 미세 거리변와에 따른 자기자화의 변화를 구현하는데 있어 비선형적인 요소를 포함하고 있어 이를 수학적으로 모델링하여 제어기를 설계하는데는 많은 난점을 내포하고 있다. 따라서 거리변화에 따른 자기장의 비선형적인 변화 관계를 신경회로망 제어기의 학습을 통하여 제어할 수 있도록 신경 회로망 제어기를 제안하려 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.419-422
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• 2003

본 논문에서는 다자간 화상회의 시스템에서 합성 입체 음향을 재현하는 방법과 음향반향제거 방법을 제안한다. 합성 입체 음향은 HRTF(head related transfer function)을 이용하여 재현하고 합성 입체 음향반향제거를 위하여 AP(affine projection) 알고리즘을 이용하여 3차원 입체음향반향 제거 방법을 제안한다. 컴퓨터 시뮬레이션 결과 제안하는 합성 입체 음향반향제거기가 효과적으로 반향을 제거할 수 있음을 보인다.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.178-188
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• 2009

In this paper, we propose the method which provides efficient sub-channel allocation for handoff and new call supporting multi-media service in AMC-based OFDMA system. Firstly, we apply the multi-band method which provides different AMC method according to the location of user terminals. Also, in OFDMA system environment that a base station has a lot of sub-channels, we adopt the sub-channel allocation scheme that provides a higher priority to handoff call and real-time service about handoff and new calls with multi-meida service. The simulation results show that the proposed scheme plays a role in increasing the number of new and handoff calls meeting the required blocking rate.

• The Transactions of the Korea Information Processing Society
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• v.3 no.3
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• pp.581-590
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• 1996

In this paper, we describe the design consideration and the system configuration of the AV service terminal which supports the multiple services simultaneously. We present a service control scheme to support the multiple services in the limited network capability and system hardware capability. The system was developed in the form of an add-on board in a PC system based on N-ISDN BRI. Through the field test in domestic N-ISDN, we confirmed the interoperability and robustness of the system. At present, the developed system can basically support the videoconference service. Also the system can support the multimedia retrieval service, messaging service, fine transmission, and group working environment.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.2 s.302
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• pp.39-48
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• 2005

In this paper, we implement the multimedia remote control system by using existing internet service or wired online. We also provide user-friendly convenient environment with developed application program named EzPlay and PC-EPG. The multimedia remote control system consists of integrated wireless transceiver of PC and TV connected USB type and the users can easily use lots of contents because EzPlay program provides appropriate UI mode on the PC and TV screen. The unposed system can operate real-time playing, reserved video receding and data storing function using internet mesh based on signal detecting control theory. The PC-EPG system is implemented by server/client web program and the client program based on visual C++/MFC processes data storing in client computer through TCP/IP. It also provides intelligent function that constructs database according to user's preference.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.28-35
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• 2011

Cooperative ARQ scheme is effective for better QoS guarantee for the next generation mobile communication systems where multimedia data transmission highly increases. In this paper, we propose a cooperative ARQ strategy in ad hoc cognitive relays for mobile multimedia communication for supporting instantaneous cooperation in MANET environment. In the proposed strategy, to support real time, delay-sensitive services, whenever a frame is transmitted from the source, each relay actively senses the SINR of the signal transmitted from the source, and determine whether to propose retransmission or not before the destination transmits feedback signal. To minimize the false retransmission decision or needless retransmission, we propose an adaptive sensing threshold optimization algorithm to maintain suboptimal sensing thresholds for each relay. By computer simulation, it is shown that the proposed cooperative ARQ retransmission scheme outperforms the conventional schemes with respect to frame transmission delay and frame loss probability in real time multimedia data transmission system.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3097-3110
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• 1997

As to the recent advances in computer technologies and high-speed networks, telecommunication services and provision of multimedia services will be provided on the basic of a new software architecture adapting networking infrastructure on open information networking architecture. In this paper, the video conference services has been selected as a target service example because it is expected to become one of the most important services on the full service network. In fact, it can be viewed as the basis for providing telecommunication services such as video telephony and video conferencing. This paper presents the prototyping of TINA (Telecommunication Information Networking Architecture) based desktop video conference system using the concepts of session management. The prototyping of desktop video conference system aims at assessing TINA concepts and refinement of the mapping between session graph and connection graph, and provides object modeling methodologies towards distribution and objected-orientation.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.574-584
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• 2006

Recently, ISO/IEC 23000 (also known as 'MPEG-A') has proposed a new file format called 'MAF(Multimedia Application File Format)[1]' which provides a capability of integrating/storing the widely-used compression standards for audio and video and the metadata in MPEG-7 form into a single file format. However, it is still very hard to verify the usefulness of MPEG-A in the real applications because there is still no real system that fully implements this standard. In this thesis, a design and implementation of a multimedia retrieval system based on MPEG-A standard on PC and mobile device is presented. Furthermore, an extension of MPEG-A for describing the metadata for video is also proposed. It is selected and defined as a subset of MPEG-7 MDS[4] and TV-anytime[5] for video that is useful and manageable in the mobile environments. In order to design the multimedia retrieval system based on MPEG-A, we define the system requirements in terms of portability, extensibility, compatibility, adaptability, efficiency. Based on these requirements, we design the system which composed of 3 layers: Application Layer, Middleware Layer, Platform Layer. The proposed system consists of two sub-parts, client-part and server-part. The client-part consists of MAF authoring tool, MAP player tool and MAF searching tool which allow users to create, play and search the MAF files, respectively. The server-part is composed of modules to store and manage the MAF files and metadata extracted from MAF files. We show the usefulness of the proposed system by implementing the client system both on MS-Windows platform on desk-top computer and WIPI platform on mobile phone, and validate whether it to satisfy all the system requirements. The proposed system can be used to verify the specification in the MPEG-A, and to proves the usefulness of MPEG-A in the real application.