• Journal of information and communication convergence engineering
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• 제8권4호
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• pp.399-404
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• 2010

We propose a seamless IPTV transport technology of mobile device. This technology uses multiple interfaces of wireless communication on mobile device. This proposal for transportation of mobile IPTV contents is more mobile and adaptable than other wireless technologies that are currently being used. Algorithm of proposed technology is as follow. When the signal strength of the connected wireless network interface of mobile device is getting lower than specified level, another wireless network interface is connected to continue downloading the IPTV contents in advance. Another connection is maintained until the signal strength of the first connected interface is stable or the interface is connected to another base station (or AP) that have good signal strength. For more seamless services, we consider classifying the packets of mobile IPTV and using dynamic content quality select techniques. Dynamic content quality selection is based on notifying transfer rate to the content delivery network (CDN) server. The proposed technology is expected to use efficiently with both mobile IPTV and the transportation of mobile P2P/P4P.

• 한국컴퓨터정보학회논문지
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• 제23권9호
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• pp.35-42
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• 2018

In this paper, we propose an optimal streaming service method based on Hybrid CDN/P2P architecture. Recently, video streaming utilizes a CDN (Content Delivery Network) operation technique based on a Proxy Server, which is an end node located close to a user. However, since CDN has a fixed network traffic bandwidth and data information exchange among CDNs in the network is not smooth, it is difficult to guarantee traffic congestion and quality of image service. In the hybrid CDN/P2P network, a data selection technique is used to select only the data that is expected to be continuously requested among all the data in order to guarantee the QoS of the user who utilizes the limited bandwidth efficiently. In order to search user requested data, this technique effectively retrieves the storage information of the constituent nodes of CDN and P2P, and stores the new image information and calculates the deletion priority based on the request possibility as needed. Therefore, the streaming service scheme proposed in this paper can effectively improve the quality of the video streaming service on the network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2282-2303
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• 2021

To solve the problems of heavy computing load and system transmission pressure in energy internet (EI), we establish a three-tier cloud-edge integrated EI network based on a cloud-edge collaborative computing to achieve the tradeoff between energy consumption and the system delay. A joint optimization problem for resource allocation and task offloading in the threetier cloud-edge integrated EI network is formulated to minimize the total system cost under the constraints of the task scheduling binary variables of each sensor node, the maximum uplink transmit power of each sensor node, the limited computation capability of the sensor node and the maximum computation resource of each edge server, which is a Mixed Integer Non-linear Programming (MINLP) problem. To solve the problem, we propose a joint task offloading and resource allocation algorithm (JTOARA), which is decomposed into three subproblems including the uplink transmission power allocation sub-problem, the computation resource allocation sub-problem, and the offloading scheme selection subproblem. Then, the power allocation of each sensor node is achieved by bisection search algorithm, which has a fast convergence. While the computation resource allocation is derived by line optimization method and convex optimization theory. Finally, to achieve the optimal task offloading, we propose a cloud-edge collaborative computation offloading schemes based on game theory and prove the existence of Nash Equilibrium. The simulation results demonstrate that our proposed algorithm can improve output performance as comparing with the conventional algorithms, and its performance is close to the that of the enumerative algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권5호
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• pp.1238-1259
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• 2024

Previous studies on joint optimization of computation offloading and service caching policies in Mobile Edge Computing (MEC) have often neglected the impact of dependency-aware subtasks, edge server resource constraints, and multiple users on policy formulation. To remedy this deficiency, this paper proposes a many-objective joint optimization dependency-aware task offloading and service caching model (MaJDTOSC). MaJDTOSC considers the impact of dependencies between subtasks on the joint optimization problem of task offloading and service caching in multi-user, resource-constrained MEC scenarios, and takes the task completion time, energy consumption, subtask hit rate, load variability, and storage resource utilization as optimization objectives. Meanwhile, in order to better solve MaJDTOSC, a many-objective evolutionary algorithm TSMSNSGAIII based on a three-stage mating selection strategy is proposed. Simulation results show that TSMSNSGAIII exhibits an excellent and stable performance in solving MaJDTOSC with different number of users setting and can converge faster. Therefore, it is believed that TSMSNSGAIII can provide appropriate sub-task offloading and service caching strategies in multi-user and resource-constrained MEC scenarios, which can greatly improve the system offloading efficiency and enhance the user experience.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.345-353
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• 2021

Cloud computing represent a new era of computing that's forms through the combination of service-oriented architecture (SOA), Internet and grid computing with virtualization technology. Virtualization is a concept through which every cloud is enable to provide on-demand services to the users. Most IT service provider adopt cloud based services for their users to meet the high demand of computation, as it is most flexible, reliable and scalable technology. Energy based performance tradeoff become the main challenge in cloud computing, as its acceptance and popularity increases day by day. Cloud data centers required a huge amount of power supply to the virtualization of servers for maintain on- demand high computing. High power demand increase the energy cost of service providers as well as it also harm the environment through the emission of CO₂. An optimization of cloud computing based on energy-performance tradeoff is required to obtain the balance between energy saving and QoS (quality of services) policies of cloud. A study about power usage of resources in cloud data centers based on workload assign to them, says that an idle server consume near about 50% of its peak utilization power [1]. Therefore, more number of underutilized servers in any cloud data center is responsible to reduce the energy performance tradeoff. To handle this issue, a lots of research proposed as energy efficient algorithms for minimize the consumption of energy and also maintain the SLA (service level agreement) at a satisfactory level. VM (virtual machine) consolidation is one such technique that ensured about the balance of energy based SLA. In the scope of this paper, we explore reinforcement with fuzzy logic (RFL) for VM consolidation to achieve energy based SLA. In this proposed RFL based active VM consolidation, the primary objective is to manage physical server (PS) nodes in order to avoid over-utilized and under-utilized, and to optimize the placement of VMs. A dynamic threshold (based on RFL) is proposed for over-utilized PS detection. For over-utilized PS, a VM selection policy based on fuzzy logic is proposed, which selects VM for migration to maintain the balance of SLA. Additionally, it incorporate VM placement policy through categorization of non-overutilized servers as- balanced, under-utilized and critical. CloudSim toolkit is used to simulate the proposed work on real-world work load traces of CoMon Project define by PlanetLab. Simulation results shows that the proposed policies is most energy efficient compared to others in terms of reduction in both electricity usage and SLA violation.

• 정보처리학회논문지D
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• 제11D권1호
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• pp.83-94
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• 2004

다양한 분산정보의 통합을 위하여 전역 사용자들이 요구하는 데이터들을 지역서버의 자치성을 유지하면서 효과적으로 제공하기 위한 미디 에이터 시스템의 연구가 활발하게 진행되고 있다. 그러나, 미디에이터에서의 전역질의를 효율적으로 처리하기 위한 방법의 연구는 상대적으로 매우 미흡한 실정이다. 미디에이터에서 전역질의는 원격지서버의 질의처리 단위인 부분질의의 집합으로 표현되어진다. 따라서, 미디에이터가 부분질의의 결과를 구체화방법으로 관리한다면 관련된 질의의 결과를 사용자에게 신속하게 제공할 수 있다. 그러나, 미디에이터에서는 통합 스키마의 변경이 자유롭고, 사용자의 질의가 자주 변할 수 있기 때문에 최적의 구체화부분질의를 결정하기 위해서 전역질의의 빈발정도를 지속적으로 파악해야 한다. 따라서, 부분질의의 수가 증가할수록 최적화의 수행시간이 매우 길어지기 때문에 부분질의 빈도의 최근의 변화를 적절하게 반영하지 못한다. 따라서 본 논문에서는 미디에이터 시스템의 저장공간의 활용율을 극대화하는 최적의 구체화부분질의 군을 선택하는 방법을 제안한다. 또한 과거와 최근의 부분질의의 활용형태가 다양하게 변할 수 있으므로 시간에 따른 감쇄율을 활용빈도에 적용하여 최근의 활용빈도의 변화에 민감하게 반응하고 활용형태의 변화에 따라 적응적으로 새로운 구체화부분질의 군을 선택할 수 있는 방법을 제안한다.

• 방송공학회논문지
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• 제25권1호
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• pp.94-104
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• 2020

현재 유무선 인터넷을 통한 미디어 소비는 대부분 ISO/IEC MPEG(Moving Picture Experts Group)에 의해 표준화된 미디어 스트리밍 방식인 DASH(Dynamic Adaptive Streaming over HTTP) 또는 이와 유사한 형태의 적응형 미디어 스트리밍(adaptive media streaming) 기술에 의해 시행되고 있다. 이들은 모두 ISP(Internet Service Provider)가 웹서비스를 원활하게 제공하기 위해 충분히 설치할 수밖에 없는 HTTP 캐시(cache)에 크게 의존한다. 결과적으로 미디어 스트리밍 사용자 증가에 따라 CDN(Contents Delivery Network) 사업자의 서버 증설 부담 대신 ISP의 HTTP 캐시 증설 부담이 커지게 되었다. 이로 인해, ISP들은 이러한 HTTP 증설 비용을 보전하기 위해 CDN 사업자에게 미디어 트래픽 비용을 부과하게 되었다. 최근 이러한 비용을 줄이고자 P2P(Peer-to-Peer) 통신을 함께 사용하는(P2P-assisted) DASH 방식이 제안되었다. 또한 이러한 P2P 통신 병용 DASH 시스템의 효율을 극대화하여 CDN 사업자의 비용을 최대한 절감시키는 피어 선택 알고리듬도 연구되었다. 그러나 이 알고리듬은 선택된 피어에게 부담을 집중시키는 경향이 있다. 본 논문에서는 피어의 부담을 여러 피어들에게 분산시키면서도 CDN 사업자의 비용 절감 수준을 적절하게 유지하는 새로운 피어 선택 알고리듬을 제안하고, 이를 WebRTC(Web Real-Time Communication) 표준 API를 활용한 웹기반 스트리밍 시스템에 구현한 후, 실험을 통해 제안한 알고리듬의 효용성을 검증하였다.

• Journal of Veterinary Science
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• 제24권4호
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• pp.51.1-51.17
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• 2023

Background: To date, various genotypes of infectious bronchitis virus (IBV) have co-circulated and in Korea, GI-15 and GI-19 lineages were prevailing. The spike protein, particularly S1 subunit, is responsible for receptor binding, contains hypervariable regions and is also responsible for the emerging of novel variants. Objective: This study aims to investigate the putative major amino acid substitutions for the variants in GI-19. Methods: The S1 sequence data of IBV isolated from 1986 to 2021 in Korea (n = 188) were analyzed. Sequence alignments were carried out using Multiple alignment using Fast Fourier Transform of Geneious prime. The phylogenetic tree was generated using MEGA-11 (ver. 11.0.10) and Bayesian analysis was performed by BEAST v1.10.4. Selective pressure was analyzed via online server Datamonkey. Highlights and visualization of putative critical amino acid were conducted by using PyMol software (version 2.3). Results: Most (93.5%) belonged to the GI-19 lineage in Korea, and the GI-19 lineage was further divided into seven subgroups: KM91-like (Clade A and B), K40/09-like, QX-like (I-IV). Positive selection was identified at nine and six residues in S1 for KM91-like and QX-like IBVs, respectively. In addition, several positive selection sites of S1-NTD were indicated to have mutations at common locations even when new clades were generated. They were all located on the lateral surface of the quaternary structure of the S1 subunits in close proximity to the receptor-binding motif (RBM), putative RBM motif and neutralizing antigenic sites in S1. Conclusions: Our results suggest RBM surrounding sites in the S1 subunit of IBV are highly susceptible to mutation by selective pressure during evolution.

• 정보처리학회논문지C
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• 제10C권5호
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• pp.565-574
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• 2003

본 논문에서는 한국정보보호진흥원에서 계층적 침입시도 탐지 및 대응을 위해 개발하였던 SDMS-RTIR(Scan Detection Management System with Real Time Incidence Response)을 지원하는 침입탐지 메시지 교환 프로토콜 라이브러리 IDMEPL을 구현하였다. IDMEPL은 IDWG의 IDMEF와 IAP를 기반으로 이기종의 침입(시도)탐지 시스템과 SDMS-RTIR의 실시간 상호연동을 제공하며 TLS 프로토콜을 통해 보안위협에 안전한 메시지 교환을 지원한다. 특히, IDMEPL은 유연성 있는 침입탐지 메지시 교환 프로토콜 선택 과정과 패스워드 기반의 암호화 프로토콜을 제공함으로써 각 침입(시도)탐지 시스템들로 하여금 자신의 네트워크 환경에 적절한 메시지 교환 프로토콜과 암호화 통신 방법을 선택할 수 있게 하였다. 이처럼 IDMEPL이 탑재된 SDMS-RTIR은 대규모의 네트워크 환경에서 이기종의 다양한 침입(시도)탐지 시스템들로부터 침입탐지 메시지를 실시간으로 접수하고 분석할 수 있다.

• 정보처리학회논문지C
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• 제17C권5호
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• pp.399-406
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• 2010

유비쿼터스 네트워크 환경에서 다양한 데이터 서비스가 가능해지면서 악의적인 공격자나 내부 사용자에 의한 보안 취약성 및 프라이버시 침해로 인한 문제를 해결하기 위해 다양한 콘텐츠나 대용량 데이터의 안전한 보안 관리 문제가 주요 이슈로 떠오르고 있다. 기존 다항식 기반을 이용한 Ito, Saito, Nishizeki 할당 방식은 분산된 비밀정보를 복원하기 위해 Share 모두가 필요하게 된다. 반면, 본 제안 방식의 경우, 임계치 이상의 Share가 모아지면 비밀정보를 복원할 수 있다. 또한, 데이터를 분산 복원하는 분산 DBMS 운영상의 효과 특히, 데이터베이스(DB) 서버 및 Share 선택의 규칙성이 있고 조합적 구조인 Combinatorial Design상의 파라메터 t,v,k를 이용함으로써 구현상의 유연성(flexibility)을 갖는다. 본 논문에서는 Share의 할당 문제를 해결하고자 비밀분산 방식을 이용하여 데이터를 분산저장관리 할 때 Share의 할당을 위해 t-(v,k,1) 디자인이 갖는 행렬구조를 적용시킴으로써 새롭게 Share 할당법을 구성하고 데이터 분산저장관리에의 응용에 대해 검토한다.