• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3495-3501
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• 2010

Because the application simultaneously to transmit large amounts of data (Video conferencing, Internet broadcasting, Online games etc.) to multiple users increases, the importance and utilization of group communication was greater. So the security was recognized as a important issue. To provide security in multicast environment, A study of single group management server using protocol based on Key Tree Scheme was proposed. But the paper proposes secure group key management scheme to be a relatively low-overhead. Therefore proposed paper is demonstrated to be excellent by comparing the effectiveness of existing and proposed group key management scheme.

• Journal of Integrative Natural Science
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• v.11 no.4
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• pp.192-196
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• 2018

The mobile agent paradigm can be exploited in a variety of ways, ranging from low-level system administration tasks to middle ware to user-level applications. Mobile agents can be useful in building middle-ware services such as active mail systems, distributed collaboration systems, etc. An active mail message is a program that interacts with its recipient using a multimedia interface, and adapts the interaction session based on the recipient's responses. The mobile agent paradigm is well suitable to this type of application, since it can carry a sender-defined session protocol along with the multimedia message. Mobile agent communication is possible via method invocation on virtual references. Agents can make synchronous, one-way, or future-reply type invocations. Multicasting is possible, since agents can be aggregated hierarchically into groups. A simple check-pointing facility has also been implemented. Another proposed solution is to use multi agent computer systems to access, filter, evaluate, and integrate this information. We will present the overall architectural framework, our agent design commitments, and agent architecture to enable the above characteristics. Besides, the each information needed a mobile agent system such as text, graphic, image, audio and video etc, constructed a great capacity multimedia database system. However, they have problems in establishing connections over multiple subnetworks, such as no end-to-end connections, transmission delay due to ATM address resolution, no QoS protocols. We propose a new connection management scheme in the thesis to improve the connection management involved of mobile agent systems.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.205-216
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• 2010

In this paper, a method of MPEG-2 Transport Stream (TS) multiplexing for Ultra HDTV (UHDTV) and its design and implementation as a SW tool is described. In practice, UHD video may be divided into several HD videos and each video is encoded in parallel. Therefore, it is necessary to synchronize and multiplex multiple bitstreams encoding each HD video for transmitting and storing UHD video. In this paper, it is assumed that 4 HD videos partitioning a UHD spatially are encoded as H.264/AVC and two 5.0 channel audios are encoded by AC-3. Therefore, 4 H.264/AVC elementary streams (ESs) and 2 AC-3 ESs is mainly considered in the TS multiplexing of UHD. For the carriage of H.264/AVC and AC-3 over MPEG-2 TS, PES packetization and TS multiplexing are designed and implemented based on the extended specification of the MPEG-2 Systems and ATSC (Digital audio compressed standard), respectively. The implemented UHD TS multiplexing tool emulates real time HW operation in the time unit corresponding to the duration of one TS packet transmission in a given TS rate. In particular, in order to satisfy the timing model, the buffers defined in the TS System Target Decoder (T-STD) are monitored and their statuses are considered in the scheduling of TS multiplexing. For UHD multiplexing, two kinds of multiplexing structures, which are UHD re-multiplexing and UHD program multiplexing, are implemented and their strength and weakness are investigated. The developed UHD TS multiplexing tool is tested and verified in terms of the syntax and semantics conformance and functionalities by using a commercial analyzer and real-time presentation tools.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.1-12
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• 2002

In the multimedia CDMA mobile communication service, it is required to support various applications, such as voice, video, file transfer, e-mail, and Internet access, with guaranteed QoS. In the mixed traffic environment ,which consists of voice, stream data, and packet data, we analyze the network where preemptive priority is granted to delay-intolerant voice service and a buffer is offered to delay-tolerant stream data service. And, for best-effort packet data service, the access control by transmission permission probability is applied to obtain prominent throughput. To analyze the multimedia CDMA mobile communication system, we build a 2-dimensional markov chain model about prioritized-voice and stream data services and accomplish numerical analysis in combination with packet data traffic based on residual capacity equation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.1033-1036
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• 2013

A study about collision resolution is needed because huge file, video and multimedia information are transmitted to wireless LAN. CSMA/CR protocol guarantees fairness, but doesn't consider QoS. To practicalize CSMA/CR protocol in saturation fully-connected single hop network environments, this paper proposes method of collision compensation. previous CSMA/CR protocol chooses CR Slot only considering fairness, but this paper chooses front CR Slot for compensation of collision to station experiencing collisions. The station transmits jam signal and has channel priority of transmission. So transmitting efficiency and successful transmission probability rise. This proposed simple method can offer benefit to station experiencing collisions without additional hardware cost.

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.1-12
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• 2022

As the performance of Unmanned Aerial Vehicles (UAVs) are improving and the prices are lowering, it is expected that the use of UAVs will continuously grow in the future. It is important to always maintain control signal and video communication to operate remote UAVs stably, especially in military UAV operations, as unexpected jamming attacks can result in fatal UAV crashes. In this paper, to improve the network reliability and low latency when supporting UAV operations, the anti-jamming performance of Second generation Anti-jam Tactical UHF Radio for NATO (SATURN) networks is analyzed and enhanced by applying Forward Error Correction (FEC) and Minimum Shift Keying (MSK) modulation as well as Hamming code based multiple transmission techniques.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.463-478
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• 2008

A Distributed Translator Network(DTxR) is a cost-effective and frequency-effective method which can use existing transmission utilities and can be constructed in a shorter time as compared with Multiple Frequency Network(MFN) or Single Frequency Network(SFN) using On Channel Repeater(OCR). In order to verify the feasibility of DTxR, this field test was done in 30 points of north-west area in Seoul using 3rd, 5th, and 6th generation DIV receivers. Electric field strength, noise margin and ease of reception were measured and subjective evaluation of video quality was done in these points during the field test. With the test result, an improvement of receiving quality was obtained and an ease of reception was increased in case of the 5th. and 6th. receiver. From the results, we conclude that DTxR is a feasible method in DIV networks.

• Journal of Broadcast Engineering
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• v.22 no.5
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• pp.560-569
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• 2017

Recently as the studies on the combined delivery over multiple transmission media are progressed, studies using MMT which is next-generation multimedia transport standard are underway. They are about transmitting video data layered by SHVC through broadcasting network and communication network based on MMT. However, it is difficult to serve synchronized UHD contents in heterogeneous network environment based on MMT, because MMT standard doesn't fully specify the information to indicate the relationship between media. Also, the service that we want to propose in this paper is a broadcasting-based service such as terrestrial broadcasting. Therefore the user must be able to watch various contents continuously. However, the MMT PI(Presentation Information) that controls the spatio-temporal layout of a content has been described as providing only one content. In this paper, we propose the structure of MXD document and MMT PI to provide continuous UHD contents service based on heterogeneous network.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.101-109
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• 2011

In this paper, we present a new routing protocol, multipath and multi-priority based routing protocol, (MMRP) for wireless multimedia sensor networks. The proposed MMRP chooses the multiple routing paths from source to the sink, then the selected paths are assigned with different priority levels depending upon the residual energy and transmission delay in the routing paths. That is, the highly prioritized I frames of the MPEG video are transmitted over the high priority routing paths, and other P and B frames are transmitted over the lower priority routing paths. The proposed MMRP protocol can be applied to time critical applications which require both lower latency and low power consumption over wireless multimedia sensor network. Simulations results of MMRP protocol show respectively an improvement of 23.48% and 23.11% in energy conservation and 81.6% and 32.01% improvement in latency as compared to protocols without and with multipath routing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2653-2663
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• 1997

The successive and parallel interference cancellation schemes are two well-known types of multi-stage interference cancellation schemes using the conventional correlator receivers as a basic building block, which has been known to significantly improve the performance of DS/CDMA system in the multiple access communication. Performance comparison between these two schemes is made strictly based on the analytical and it has been shown that the successive interference cancellation (SIC) scheme is more resistant to fading than the parallel interference cancellation (PIC) scheme. We further investigate the performance of the successive IC scheme subject to the delay constraint, which may be imposed typically on most of service applications with a real-time transmission requirement, including speech and video applications. Our analysis demonstrates that the performance may be significantly improved by the groupwise successive interference cancellation (GSIC) scheme, which can be properly optimized to meet the given delay constraint.