• Journal of KIISE:Computer Systems and Theory
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• v.30 no.7_8
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• pp.359-369
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• 2003

We present efficient generalized algorithms for all-to-all personalized communication operations in a 2D torus. All-to-all personalized communication, or complete exchange, is at the heart of numerous applications, such as matrix transposition, Fast Fourier Transform(FFT), and distributed table lookup. Some algorithms have been Presented when the number of nodes is power-of-2 or multiple-of-four form, but there has been no result for general cases yet. We first present complete exchange algorithm called multiple-Hop-2D when the number of nodes is in the form of multiple-of-two. Then by extending this algorithm, we present two algorithms for an arbitrary number of nodes. Split-and-Merge algorithm first splits the whole network into zones. After each zone performs complete exchange, merge is applied to finish the desired complete exchange. By handling extra steps in Double-Hop-2D algorithm, Modified Double-Hop-2D algorithm performs complete exchange operation for general cases. Finally, we compare the required start-up time for these algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.69-70
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• 2009

단거리에서의 MCU들의 통신을 위해서 직렬방식의 통신이 많이 사용되어지고 있다. 이러한 시리얼 통신에서도 통신 규격을 변경하면 일대일 통신뿐만 아니라 다대다 통신을 통한 네트워크 구성도 가능하다. 네트워크로 구성되어지는 시리얼 통신에서 각 MCU들의 원활한 통신을 위한 방법이 필요하기 때문에, 본 논문에서는 그 방법을 Ethernet의 패킷 데이터그램 형태를 응용하여 시리얼 통신에서의 데이터 패킷을 메시지단위로 통신하는 방법을 제안한다.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.13-20
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• 2015

This paper proposes a Near Field Communication (NFC) communication system that exchanges information of digital business cards efficiently for many to many communication to solve inconvenience of one-to-one communication when people exchanges business cards each other in meetings such as conference, forum, seminar. The proposed system can provide people to exchange contact information one-to-one as well as multiple members at once using a digital business card system that consists a server and a database based on NFC communication. The system has been developed to collect business card information from a NFC reader and to transfer it directly to a smartphone application effectively. The system can manage business card information with the application effectively and provide security in order to prevent from leakage of private information when transferring contact data.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.160-162
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• 2005

인터넷의 발전에 따라 다자간 그룹 통신 환경이 주목을 받게 되었고 이를 위해 다대다 멀티캐스트를 이용한 통신 기법들이 제안되었다. 이들 중 ECTP-5는 다대다 멀티캐스트의 신뢰성 보장을 위해 단일 공유 제어 트리와 주기적 제어 메시지를 통한 복구 요청 및 재전송 데이터의 멀티캐스트 등을 통해 에러 복구를 지원한다. 그러나 창가자의 수가 늘어남에 따라 트리 유지 비용 및 에러 복구 비용에 따른 확장성의 문제가 발생한다. 이를 해결하기 위해 본 논문에서는 2-계층 논리 트리를 이용한 제어 트리 관리 기법과 유니캐스트 기반의 제어메시지를 활용하는 에러 복구 기법을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.223-227
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• 2006

인터넷의 발전에 따라 다자간 그룹 통신 환경이 주목을 받게 되었고 이를 위해 다대다 멀티캐스트를 이용한 통신 기법들이 제안되었다. 이들 중 GAM (Group Aided Multicast) 은 다대다 멀티캐스트의 신뢰적 전달을 보장하기 위해 트리 기반의 손실 복구 기법을 제안하고, 제어 트리 관리 비용과 손실 복구 효율성간의 접점을 찾기 위해 그룹 개념을 도입하고 그룹의 대표로서 코어 노드를 정의한다. 코어 노드는 네트워크 상의 특정 지점에 미리 설치된 전용 노드로서 그룹 내의 손실 복구와 그룹 간의 손실 제어를 담당한다. 그러나 이러한 전용 코어 노드의 도입은 프로토콜의 가용성을 제한하고 코어 노드의 설치 부담을 가지게 된다. 따라서 본 논문에서는 별도의 코어 노드의 설치 없이 프로토콜이 동작할 수 있도록 세션 참가자 중에서 코어 노드를 동적으로 선택하고, 로컬 그룹 노드 중에서 제어 트리의 효율성을 최대한 보장하는 노드의 위치를 결정하는 기법을 제안한다.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.1
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• pp.48-56
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• 2023

This paper implements many-to-many communication between users and develops a multi-functional smart helmet for worker protection and environmental safety in the shipbuilding and shipping industry. First, the communication situation is recorded in the field to perform signal processing for noise that interferes with communication. Then, it deals with the contents of developing smart helmets, data acquisition, algorithms, and simulations. The simulation results analyzed by applying the adaptive algorithm are shown, and their usefulness is confirmed. In conclusion, looking at the optimization process for the convergence factor of the Least Mean Square and Filtered-x Least Mean Square Adaptation Algorithm was possible. It is thought that it has laid the foundation for implementing many-to-many communication, the function of smart helmets that reduces or removes various noises at the shipyard in the future.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.484-485
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• 2003

고전적인 Client/server환경에서의 통신은 Lan 환경하의 동기적 일대일 통신 기반 이였다. 그러나 인터넷이 확산되고 일반화되면서 많은 소프트웨어들은 Cluster 또는 Grid 같은 분산시스템 환경과 핸드폰, PDA 같은 Mobile환경에서 개발되고 있다. 이러한 환경은 WAN기반의 비동기적 일대다 다대다 통신을 기반으로 한다. 본 논문은 이러한 환경에 적합한 애플리케이션에 독립적이고 비동기 통신을 제공하며 각 통신요소(Event Supplier, Consumer)를 그룹으로 묶어 동적으로 관리해주는 기능을 제공하는 Event Channel Service를 제안한다. 이 Event Channel Service는 Event Channel을 사용하여 Event Supplier와 Consumer를 분리하며 Push. Pull 방식으로 Event를 전달할 수 있는 구조를 제공한다. 또한 다양한 Protocol을 지원하고 Quality of Service를 제공한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.525-527
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• 2005

the multicast services with multiple senders is interested according to the internet services such as multiple audio/video conference services. With the N-plex multicast protocols, multicast session manager is also needed for membership control and session control. RMCP-3 is designed for N:N group communications which is standardizing in ITU-T and supports multiple senders who join sessions. In this paper, we consider requirements of multicast manager for multiplex multicast communication protocol which many a joiner has a role in sender such conference application.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.656-667
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• 2003

Congestion control is a key task in reliable multicast along with error control. However, existing tree-based congestion control schemes such as MTCP and TRAMCC are designed for one-to-many reliable multicast and have some drawbacks when they are used for many-to-many reliable multicast. We propose an efficient congestion control mechanism, TMRCC, for tree-based many-to-many reliable multicast protocols. The proposed scheme is based on the congestion windowing mechanism and a rate controller is used in addition. The feedback for error recovery is exploited for congestion control as well to minimize the overhead at the receivers. The ACK timer and the NACK timers are set dynamically reflecting the network condition changes. The rate regulation algorithm in the proposed scheme is designed to help the flows sharing the same link to achieve the fair share quickly The performance of the proposed scheme is evaluated using ns-2. The simulation results show that the proposed scheme outperforms TRAMCC in terms of intra- session fairness and shows good level of responsiveness, TCP-friendliness, and scalability. In addition, we implemented the proposed scheme by integrating with GAM that is one of many-to-many reliable multicast protocols and evaluated the performance in a laboratory-wide testbed.