• Journal of Broadcast Engineering
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• v.17 no.3
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• pp.503-518
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• 2012

In this paper, we propose a complexity-based parallelization method of the sample adaptive offset (SAO) algorithm which is one of HEVC in-loop filters. The SAO algorithm can be regarded as region-based process and the regions are obtained and represented with a quad-tree scheme. A offset to minimize a reconstruction error is sent for each partitioned region. The SAO of the HEVC can be parallelized in data-level. However, because the sizes and complexities of the SAO regions are not regular, workload imbalance occurs with multi-core platform. In this paper, we propose a LCU-based SAO algorithm and a complexity prediction algorithm for each LCU. With the proposed complexity-based LCU processing, we found that the proposed algorithm is faster than the sequential implementation by a factor of 2.38 times. In addition, the proposed algorithm is faster than regular parallel implementation SAO by 21%.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.3
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• pp.99-104
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• 2003

Ad-hoc is the wireless network and consists of moving Hosts in environments which don't have a network-based Frame. Because ad-hoc is considered as broadcast network and network which has useful benefits, multicast muting protocols have been studied on ad-hoc network For this work we scrutinized ad-hoc and multicast routing protocols presented in previous works. And we presents a protocol for Ad-hoc network.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.595-597
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• 2005

현재 IP 멀티캐스트의 도입의 지연으로, 기존의 유니캐스트 망 기반 멀티캐스트의 필요성이 대두되어 오버레이(Overlay) 멀티캐스트 관련 연구가 진행 중이다. 특히, 확장성 제공과 작은 오버헤드 등으로 효율적인 CBT(Core Based Trees) 기반의 오버레이 멀티캐스트에 대한 연구가 활발히 진행 중이다. 그러나 기존의 거리 매트릭(Metric) 기반의 CBT로 오버레이 트리를 구성하는 경우, 특정 라우터에 패킷이 집중되는 현상으로 인하여 혼잡이 발생하여 멀티캐스트 성능 저하뿐만 아니라 네트워크 전체 성능을 저하시킬 수 있다. 본 논문에서는 이를 해결칠기 위하여. 코어 노드를 기준으로 이웃하는 두 노드 간의 패킷 중계 방향성을 계산하는 알고리즘을 제안하고. 이 결과값을 이용하는 새로운 매트릭 기반의 CBT를 구성하고자 한다. 실험 결과, CBT 상의 자식 위치에 있는 종단 노드로 패킷을 중계하는 과정에서 중복되는 패킷 전송 경로를 최소화하여 CBT를 구성함으로써 특정 라우터에 집중되는 트래픽을 줄이거나 다른 라우터로 트래픽을 분산함으로써 혼잡 발생 가능을 낮추어 보다 안정적인 통신을 기대할 수 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.885-896
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• 2013

MTC(Machine Type Communications), providing a variety of services anytime and anywhere by connecting the cellular network to the machine and things without human intervention, is being considered as a major challenge of the next-generation communications. Currently, When a massive MTC devices simultaneously connect to the network, each MTC device needs an independent access authentication process. Because of this process, authentication signaling congestion and overload problems will cause in LTE-Advanced. In this paper, we propose a group-based authentication protocol and a key management protocol. For managing the MTC devices as group units, the proposed protocol elects a group leader and authentications only once with the core network. After the authentication is completed, a group leader manages the rest members and MME(Mobility Management Entity) by constructing a binary tree. Finally, the propose protocol analysis show that the proposed protocol not only can reduces the authentication signaling which generated in between the MTC devices and the core network but also can manages the MTC devices, efficiently.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.21-30
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• 2007

Simulation means modeling structures or behaviors of the various objects, and experimenting them on the computer system. And the major approaches are DEVS(Discrete Event Systems Specification). Petri-net or Automata and so on. But, the simulation problems are getting more complex or complicated these days, so that an intelligent agent-based is being studied. In this paper, we are describing an intelligent agent-based simulation tool, which can supports the simulation experiment more efficiently. The significances of our system can be described as follows. First, the system can provide some AI algorithms through the system libraries. Second, the system supports simple method of designing the simulation model, since it's been built under the Finite State Machine (FSM) structure. And finally, the system acts as a simulation framework by supporting user not only the simulation engine, but also user-friendly tools, such as modeler scriptor and simulator. The system mainly consists of main simulation engine, utility tools, and some other assist tools, and it is tested and showed some efficient results in the three different problems.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.583-594
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• 2002

Assuring the security of group communications such as tole-conference and software distribution requires a common group key be shared among the legal members in a secure manner. Especially for large groups with frequent membership change, efficient rekey mechanism is essential for scalability. One of the most popular ways to provide sealable rekey is to partition the group into several subgroups. In this paper, we propose a two-layered key management scheme which combines DEP and CBT, a protocol in which subgroup manager cannot access the multicast data and another that has a multi-core, respectively. We also select sub-group key management protocols suitable for our structure and design new rekey protocols to exclude the subgroup managers from the multicast data. Compared to previous protocols based on CBT, our scheme provides forward secrecy, backward secrecy and scalability. This would reduce the number of encryption and decryption for a rekey message and would improve the efficiency number of rekey messages and the amount of information related to group members that group managers must maintain compared to DEP.