• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.45-51
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• 2014

Luby transform (LT) codes are a class of ratelss codes, and they have capability of generating infinite length of parities with a given information length. These rateless codes can be effectively utilized to provide broadcasting and multicasting services where each user is in a different channel condition. For this reason, there have been a number of researches on the application of rateless codes for satellite systems. In this paper, by considering the current research status on rateless codes, we present VHLD implementation results of LT codes, for future hardware implementation for satellite systems. The results demonstrated in this paper can be utilized as a basic information on efficient utilization of rateless codes in the future satellite systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.770-778
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• 2012

In this paper, we propose a multi-path construction scheme to improve the survivability of a multicast session in military hybrid networks. A military hybrid network consists of a static backbone network and multiple mobile stub networks where some nodes are frequently susceptible to be disconnected due to link failure and node mobility. To improve the survivability of multicast sessions, we propose a construction scheme of ${\kappa}$ redundant multi-paths to each receiver. In order to take account of different characteristics of static and mobile networks, we propose quite different multi-path setup approaches for the backbone and stub networks, respectively, and combine them at the boundary point called gateway. We prove that our proposed scheme ensures that each receiver of a multicast session has ${\kappa}$ redundant paths to the common source. Through simulations, we evaluate the performance of the proposed schemes from three aspects : network survivability, recovery cost, and end-to-end delay.

• The KIPS Transactions:PartA
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• v.9A no.1
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• pp.19-28
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• 2002

A new class of applications based on event interactions are emerging for the wide-area network such as Internet, which is characterized as loose coupling, heterogeneity. and asynchrony. Content-barred publish/subscribe systems are widely being studied to implement the extent notification service for wide-area networks. In this paper, we analyze some problems of the content-based routing algorithm in SIENA, a recently developed as a representative event notification service architecture, and develop an enhanced routing algorithm.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.8
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• pp.393-398
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• 2005

In interconnection networks, a Hamiltonian path has been utilized in many applications such as the implementation of linear array and multicasting. In this paper, we consider the Hamiltonian properties of mesh networks which are used as the topology of parallel machines. If a network is strongly Hamiltonian laceable, the network has the longest path joining arbitrary two nodes. We show that a two-dimensional mesh M(m, n) is strongly Hamiltonian laceabie, if $m{\geq}4,\;n{\geq}4(m{\geq}3,\;n{\geq}3\;respectively)$, and the number of nodes is even(odd respectively). A mesh is a spanning subgraph of many interconnection networks such as tori, hypercubes, k-ary n-cubes, and recursive circulants. Thus, our result can be applied to discover the fault-hamiltonicity of such networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.12-14
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• 2021

A sensor registry system (SRS) provides semantic metadata about a sensor based on location information of a mobile device in order to solve a problem of interoperability between a sensor and a device. However, if the GPS of the mobile device is incorrectly received, the SRS receives incorrect sensor information and has a problem in that it cannot connect with the sensor. This paper proposes a dual collaboration strategy based on geographical embedding and LSTM-based path prediction to improve the probability of successful requests between mobile devices and sensors to address this problem and evaluate with the Monte Carlo approach. Through experiments, it was shown that the proposed method can compensate for location abnormalities and is an effective multicasting mechanism.

• Broadcasting and Media Magazine
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• v.17 no.2
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• pp.106-120
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• 2012

디지털기술의 발달로 전통적인 의미의 방송들이 통신에 기반한 다양한 매체들로부터 도전받고 있다. 라디오 방송도 예외는 아니어서 라디오방송의 디지털 전환을 논하고 있는 지금 인터넷방송, 팟캐스팅, 스마트폰 앱을 통한 방송 등 다양한 매체들이 라디오방송을 하고 있다. 전파를 통한 지상파 라디오 방송은 아직 우리나라에서 표준이 정해지지 않았지만 디지털 전환을 통해 주파수 효율을 높여 다양한 멀티미디어 서비스를 제공하게 될 것이고, 통신을 통한 디지털라디오 서비스는 지상파와는 달리 개인화된 맞춤형 서비스를 지향하게 된다. 이 두 가지 방식은 앞으로 차별화된 서비스로 상호 보완 발전해 나갈 것으로 보인다. 본고에서는 전파를 이용한 라디오방송의 디지털화를 위한 방식선정에 고려되어야 할 요소와 특히 방송주파수의 효율적인 활용 방안을 제시하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.844-846
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• 2004

Gnutella Protocol기반 네트워크에서 상호간 통신 및 검색과 응답과정에서 릴레이와 브로드캐스팅 되는 Query메시지들로 인해 많은 통신 부하를 초래한다. 또한 멀티 홉을 통한 질의 응답과정의 통신 오버헤드로 인해 통신 효율성이 저하된다. 따라서 본 논문에서는 Zipf's law 을 기반으로 한 검색어 캐싱기법을 통해, 검색어 및 검색된 응답 문자열의 빈도수와 랭킹, 그리고 검색된 파일의 크기와의 상관 관계를 얻어 캐싱 정책을 수립하고. 이에 따라 캐싱함과 동시에 캐싱정책을 이웃 peer에게 전과함으로써 전체적인 네트웍에서의 P2P응용 성능을 향상시킬 수 있는 캐싱 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.877-884
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• 2010

This paper presents a fast IP mobility management scheme in vehicular networks where multiple wireless network interfaces are used to perform the fast handover without packet loss and handover latency. In order to do that, the IETF standard HMIPv6 has been extended, where multiple simultaneous tunnels between the HMIPv6 MAP and the mobile gateway are dynamically constructed. The architecture for supporting multiple tunnels has been designed and both mathematical analysis and simulation using NS-2 have been done for performance evaluation.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.4
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• pp.151-160
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• 2018

The development of digital technology and the Internet has brought about a great change in the content industry. In order to keep pace with these changes, the copyright law has undergone several revisions, and the concept of "digital sound transmission" was introduced in the 2006 revision. However, in the current law, digital audio transmission is problematic in that the criteria for distinguishing between broadcasting and transmission is abstract and unclear. This ambiguity makes it difficult to judge the legal status of new music webcasting service such as "Free Litsen". Although these services are positioned as digital audion transmission, they have created a new concept of pseudo transmission because of its similarity to the audio transmission in its convenience and utility. These problems stem from the imbalance of between the development of technology and the legal system, so the change of the legal system is inevitable. Thus, this study discusses US copyright law and related cases, and then suggests solutions for pseudo transmission problems. This study suggests legislative criteria for pseudo transmission problems and legislative measures that can reduce the actual damage to the music market.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.809-816
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• 2005

MANET(mobile ad hoc network) cn be one of the access networks of BcN(broadband convergence network), and an user node requires address auto-configuration protocol for mu14i-hop environment. Some address auto-configuration protocols are proposed for independent MANET, but they don't consider BcN-accessable MANET environment. In this paper, new address auto-configuration protocol for wireless nodes is proposed. With this proposal, they ran configure their global addresses automatically in hybrid MANETs as BcN access networks. The autoconfiguration protocol modifies IPv6 NDP(neighbor discovery protocol) messages to deliver global prefix information to all wireless nodes, and avoids message boradcasting to minimize network overhead.