• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.748-750
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• 2001

최근 인터넷을 통한 네트워크 응용들의 확산은 unicast에서 multicast로 넓혀가고 있는 추세이다. 그러나 공개키 쌍을 사용하는 PKI 키 관리 및 인증기법에 반해 그룹 키 관리 및 인증기법에 대한 연구는 아직 미비한 상태이다. 따라서 본 논문에서는 동일한 보안등급을 갖는 다중 사용자들이 보다 안전하게 키를 공유하고 인증할 수 있도록 하는 그룹 키 분산 기법에서, 즉, 그룹키를 관리함에 있어서 필요한 정보보호에 대한 고찰 및 그룹 키 관리에서의 주요 처리인 join/leave 함수 처리, 다양한 그룹키 분산 기법에 관하여 연구하고 보다 안전한 키 관리 및 객체가 갖는 장점들을 포함하는 안전한 그룹 키 분산기법에 관하여 논하도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.966-969
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• 2007

In this paper, we propose a novel probing mechanism for adaptive transmission of video data based on congestion control and client state. The proposed mechanism is friendly to the network dominant transport protocols (TCP) and can reduce fluctuations compared to the previous works.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.637-640
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• 2010

VoIP 패킷을 전송하는데 있어서 MAC Header는 패킷의 데이터 크기에 비해 많은 대역폭을 할당 받고 있기에 제한된 무선자원의 사용에 부담이 되고 있다. 이러한 문제를 해결하기 위해 패킷 압축기법이나 패킷번들링을 이용하여 부하를 줄이기 위한 연구가 진행되고 있으며, 효율적인 무선 자원 이용의 향상을 가져올 수 있다. 따라서 본 연구에서는 WiMAX 시스템에서 스케줄링 서비스에 따른 VoIP서비스에서의 성능 분석을 하였다.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.93-101
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• 2002

This paper presents the Internet audio broadcasting technology based on the streaming technology. In this paper, we choose the MPEG-2 AAC for multimedia data, and for the streaming of this data we use RTP/RTCP protocol. We use RTSP protocol for the control of streaming data and TCP/IP for the exchange of information between server and client. By using all of these protocols and MPEBG-2 AAC, we explain the implementation method for the unicast/multicast streaming server/client system. Our system was tested by ETRI intranet, which is connected by 2000 researchers. Experimental result show that our system can be process the packet loss and jitter by retransmission and variable length buffer. Multicast streaming server can be used for the audio broadcasting service inside the company, unicast streaming server can be used for the AOD (Audio On Demand) service.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.61-71
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• 2017

ARP Spoofing is a basic and core hacking technology for almost all sniffing. It makes change the flow of packets by faking the 2nd layer MAC address. In this paper we suggested an efficient hacking technology for sniffing remote servers in the switched network environment. The suggested 'Faked ARP Reply Unicast Spoofing' makes the bidirectional packets sniffing possible between the client and server, and it makes simplify the procedures for ARP sniffing and hacking program. In this paper we researched the network hacking and implementation technologies based on the suggested ARP spoofing. And we researched various types of servers hacking such as Root ID and PW of Telnet/FTP server, Root ID and PW of MySQL DB server, ID and PW of Web Portal Server, and account information and transaction history of Web Banking Server. And also we researched the implementation techniques of core hacking programs for the ARP Spoofing.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.883-891
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• 2008

Multiple antenna orthogonal frequency division multiplexing (OFDM) is a promising technique for the high downlink-capacity in the next generation wireless systems, in which adaptive resource allocation is an important research issue that can significantly improve the performance with guaranteed QoS for users. However, most of the current resource allocation algorithms are limited to unicast system. In this paper, dynamic resource allocation is studied for multiple antenna OFDM based systems with multicast service. In the simulation, the performance of multicast system was compared with that of the unicast system. Numerical results also show that by using the proposed algorithms the system capacity is significantly improved compared with the conventional scheme.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.131-140
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• 2011

Smart packet agent is an application that is proposed to provide routing protocol and service module in ubiquitous network environment. However, it uses multi-hop broadcast, thus it causes increasing network traffic, low-speed data transmission, and the unnecessary joining nodes. In this paper, a transmit technique that uses unicast-based multi-hop to have lower network traffic and faster transmission time than the multi-hop broadcast technique. In our scheme, u-Zone Master establishes temporary routing paths by calculating moving nodes' hop-counter. Therefore, it reduces smart packet agent's network traffic and retransmission rate. Besides, this paper proposed an UDP transmission that bases on sliding window. Hence, the Stop & Wait transmission speed is improved. The results, which are taken by analyzing performance prove that the proposed scheme has better performance.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.266-274
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• 2003

One of the major issues in current on-demand routing protocols for ad hoc networks is the high resource consumed by route discovery traffic. In these protocols, flooding is typically used by the source to broadcast a route request (RREQ) packet in search of a route to the destination. Such network-wide flooding potentially disturbs many nodes unnecessarily by querying more nodes than is actually necessary, leading to rapid exhaustion of valuable network resources such as wireless bandwidth and battery power. In this paper, a simple optimization technique for efficient route discovery is proposed. The technique proposed herein is location-based and can be used in conjunction with the existing Location-Aided Routing (LAR) scheme to further reduce the route discovery overhead. A unique feature of our technique not found in LAR and most other protocols is the selective use of unicast instead of broadcast for route request/query transmission made possible by a novel reuse of routing and location information. We refer to this new optimization as the UNIQUE (UNIcast QUEry) technique. This paper studies the efficacy of UNIQUE by applying it to the route discovery of the Dynamic Source Routing (DSR) protocol. In addition, a comparative study is made with a DSR protocol optimized with only LAR. The results show that UNIQUE could further reduce the overall routing overhead by as much as 58% under highly mobile conditions. With less congestion caused by routing traffic, the data packet delivery performance also improves in terms of end-to-end delay and the number of data packets successfully delivered to their destinations.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.29-35
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• 2016

High-availability seamless redundancy (HSR) is a fault-tolerant protocol for Ethernet networks that provides two frame copies for each frame sent. Each copy is forwarded on a separate physical path. HSR is a potential candidate for several fault-tolerant Ethernet applications, including smart-grid communications. However, the major drawback of the HSR protocol is that it generates and circulates unnecessary frames within connected rings regardless of the presence of a destination node in the ring. This downside degrades network performance and can deplete network resources. Two simple but efficient approaches have previously been proposed to solve the above problem: quick removing (QR) and port locking (PL). In this paper, we will present a hybrid approach, QRPL, by combining QR with PL, resulting in further traffic reductions. Our analysis showed that network traffic is significantly reduced for a large-sized HSR connected ring network compared to the standard HSR protocol, QR, and PL.

• Journal of Internet Computing and Services
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• v.8 no.1
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• pp.25-31
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• 2007

The development of efficient Quality of Service (QoS) routing algorithms in high speed networks is very difficult since divergent services require various quality conditions, If the QoS parameter we concern is to measure the delay on that link, then the routing algorithm obtains the Least Delay (LD) path, Meanwhile, if the parameter is to measure of the link cast, then it calculates the Least Cost (LC) path. The Delay Constrained Least Cast (DCLC) path problem of the mixed issues on LD and LC has been shown to be NP-hard. The path cost of LD path is relatively mere expensive than that of LC path, and the path delay of LC path is relatively higher than that of LD path in DCLC problem. In this paper. we propose the algorithm based on estimated path for the DCLC problem and investigate its performance, It employs a new parameter which is probabilistic combination of cost and delay, We have performed empirical evaluation that compares our proposed algorithm with the DCUR in various network situations.