• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.427-436
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• 2003

Many applications that are transport multimedia data through the networks should put existing network structure to practical use. Because the existing network structure and protocols are designed for static data transmission, multimedia applications with timing concept have limitations for using existence. In this paper, we present limitations of existing network structure for multimedia delivery, survey network element's characteristics in side view of multimedia application, present the streaming protocol for realtime multimedia traffic. Lastly, we consider a protocol stack for MPEG-21 Digital Item transmission using these existing protocols.

• Journal of Digital Convergence
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• v.13 no.11
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• pp.141-148
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• 2015

In this paper, for developing and implementing the HLS(Http Live Streaming) transmitter based embedded linux which is operated easily and cheap and lower power, portable in all networks and client environments compared to exist video live streaming transmitters. We design the developed HLS transmitter hardware using the Arm11 core and then porting the Embedded Linux OS(Operating System) and implementing the HLS protocol using the open source FFmpeg and Segmenter. For proving the performance of developed HLS transmitter, we make the testing environment for testing the performance of HLS transmitter including the notebook, iPhone, android Phone, Notebook and then analysis the received video in the client displayer. In this paper, we suggest the developed HLS transmitter performance data values higher than the Apple company's HLS recommended specification values and the picture of developed HLS transmitter operation in the testing environment. The application field of this paper result is that the man who works in the emergency situation take HLS and transmit the live emergency situation to the head quarter using this portable HLS.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.691-700
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• 2003

Due to the fast development of wire&wireless internet and computer hardware, more and more internet services are being developed, such as Internet broadcast, VoD (Video On Demand), etc. So QoS (Qualify of Service) is essentially needed to guarantee the quality of these services. Traditional Internet is Best-Effort service in which all packets are transported in FIFO (First In First Out) style. However, FIFO is not suitable to guarantee the quality of some services, so more research in QoS router and QoS protocol are needed. Researched QoS router and protocol are high cost and inefficient because the existing infra is not used. To solve this problem, a new QoS control method, named Network Adaptive QoS, is introduced and applied to client/server-based streaming systems. Based on network bandwidth monitoring mechanism, network adaptive QoS control method can be used in wire&wireless networks to support QoS in real-time streaming system. In order to reduce application cost, the existing streaming service is used in NAQoS. A new module is integrated into the existing server and client. So the router and network line are not changed. By simulation in heavy traffic network conditions, we proved that stream cannot be seamless without network adaptive QoS method.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.460-471
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• 2004

Since the RTP is suitable for real-time data transmission in multimedia services like VoD, AoD, and VoIP, it has been adopted as a real-time transport protocol by RTSP, H.323, and SIP. Even though the RTP protocol stack for embedded systems has been in great need for efficient support of multimedia services, such a stack has not been developed yet. In this paper, we explain embeddedRTP which supports the RTP protocol stack at the kernel level so that it is suitable for embedded systems. Since embeddedRTP is designed to reside in the UBP module, existing applications which rely ell TCP/IP services can proceed the same as before, while applications which rely on the RTP protocol stack can request HTP services through embeddedRTp API. EmbeddedRTP stores transmitted RTP packets into per session packet buffer, using the packet's port number and multimedia session information. Communications between applications and embeddedRTP is performed through system calls and signal mechanisms. Additionally, embeddedRTP API makes it possible to develop applications more conveniently. Our performance test shows that packet-processing speed of embeddedRTP is about 7.5 times faster than that oi VCL RTP for multimedia streaming services on PDA in spite that its object code size is reduced about by 58% with respect to UCL RTP's.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.427-430
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• 2024

본 논문에서는 그리드 컴퓨팅에서의 안전한 통신을 위한 양자내성암호 기반 사용자 인증 및 키 교환 프로토콜을 구현하고 성능을 측정한다. 디지털 서명을 통해 사용자를 검증하고 암호키를 교환하여 신뢰할 수 있는 사용자들만이 그리드 컴퓨팅에 참여할 수 있도록 한다. 사용자 인증과 키 교환 과정에 NIST 선정 표준양자내성암호인 ML-DSA와 ML-KEM을 적용하여 양자컴퓨터를 이용한 공격에도 안전할 것으로 기대된다. 본 논문에서는 양자내성암호를 적용한 프로토콜이 기존의 현대암호 기반 전자서명이나 키 교환 과정에 비해 양자내성과 동시에 준수한 사용성을 지녔음을 보인다. 이를 통해 그리드 컴퓨팅의 시스템의 P2P 특성에서 기인하는 보안 문제를 해결하고, 기존에 주로 내부망이나 실시간 스트리밍 서비스에서 활용되던 그리드 컴퓨팅의 인터넷 환경으로의 확장 가능성을 제시한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.285-289
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• 2004

Recently, due to the high development of the internet, needs for multimedia streams such as digital audio and video is increasing much more. In case of transmitting multimedia streams using the User Datagram Protocol (UDP), it may cause starvation of TCP traffic on the same transmission path, thus resulting in congestion collapse and enormous delay because UDP does not perform TCP-like congestion control. Because of this problem, diverse researches are being conducted on new transmission schemes and protocols intended to efficiently reduce the transmission delay of real-time multimedia streams and perform congestion control. The TCP-friendly congestion control schemes can be classified into the window-based congestion control, which uses the general congestion window management function, and the rate-based congestion control, which dynamically adjusts transmission rate by using TCP modeling equations and the like. In this paper, we suggest the square-root congestion avoidance algorithm with the hybrid TCP-friendly congestion control scheme which the window-based and rate-based congestion controls are dealt with in a combined way. We apply the proposed algorithm to the existing TEAR. We simulate the performance of the proposed TEAR by using NS, and the result shows that it gives better improvement in the stability needed for providing congestion control than the existing TEAR.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.106-111
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• 2006

현재 다양한 상용망에서 끊김 없이 동일 서비스를 이용하고자 하는 사용자의 요구를 충족시키기 위해서 상용망을 IP 프로토콜로 융합하는 차세대 인터넷, 즉 NGN (Next Generation Network) 망이 도입되었다. 이와 같이 연결망의 대역폭이 확장되면서 다양한 멀티미디어 서비스에 대한 요구가 늘어나게 되고 나아가 실시간 TV 스트리밍 서비스에 대한 요구가 극대화되었다. 본 논문에서는 NGN과 IPTV의 서비스 정의 및 요구 사항을 분석하여 NGN의 응용 서비스로서 사용되기 위한 IPTV 서비스의 필요 요건이 무엇인지를 도출하였다. 나아가 NGN의 이동성 및 다양성 등의 특성에 따른 전송 경로의 다양화, 손실 차별화, 서비스 끊김 등의 문제점을 도출하고 이를 해결하기 위해 고려해야 하는 연구 이슈 및 방향 등에 대해 기술한다.

• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.492-504
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• 2009

The delivery of multimedia that efficiently adapts its bit-rate to changing network characteristics and conditions is one of the important challenging tasks in the design of today's real-time multimedia streaming systems such as IPTV, Mobile IPTV and so on. In these work, the primary focus is on network congestion, to improve network stability and inter-protocol fairness. However, these existing works have problems which do not support QoE (Quality of Experience), because they did not consider essential characteristics of contents playback such as the media continuity. In this paper, we propose a novel rate control scheme for improving the QoE of multimedia streaming service in the Internet congestion, called NCAR (Network and Client-Aware Rate control), which is based on network-aware congestion control and client-aware flow control scheme. Network-aware congestion control of the NCAR offers an improving reliability and fairness of multimedia streaming, and reduces the rate oscillation as well as keeping high link utilization. Client-aware flow control of NCAR offers a removing the media discontinuity and a suitable receiver buffer allocation, and provides a good combination of low playback delay. Simulation results demonstrate the effectiveness of our proposed schemes.

• Journal of Internet Computing and Services
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• v.9 no.5
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• pp.153-163
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• 2008

Almost literature has so far proposed the modifications to IEEE 802.11 DCF MAC protocol to improve system throughput and average delay. Jitter(variance in packet delays) is, however, considered as an important QoS parameter for real-time streaming service which is popularized increasingly. Unfortunately, legacy access protocol for WLAN can't support the jitter. This paper proposes two schemes modifying the DCF MAC protocol to reduce the average value of jitter for multimedia frames arrived at received nodes. The one scheme, referred to as DCW-DCF(Decreasing Contention Window-DCF), reduces CW(Contention Window) size by half whenever a transmitted frame collided against other frames and back-off happens. Also, it increase initial CW size according as the link utilization and the collision probability increase. The other scheme, referred to as D-DIFS(Differential-DIFS), assigns different values to DIFS. That is, the DIFS interval is deceased as the number of back-off for a frame increases. In this paper, the two schemes are evaluated through simulation using ns2 and simulation results show that the proposed schemes are effective for improving the jitter property of standard WLAN.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.565-570
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• 2015

In this paper, we implemented the smart door lock system that control remotely devices using the concept of internet of things. Internet of things is intelligent system that can help devices to communicate with people and devices. And recently internet of things is getting attention because of advance of hardware technology and big data. The smart doorlock system based on internet of things used raspberry pi, sensor and doorlock. Using the smart phone, doorlock can be controlled from the raspberry pi server. And the user can identify some people that is in front of doorlock. also user can check around of doorlock in realtime using the raspberry pi camera.