• 한국멀티미디어학회논문지
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• 제11권4호
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• pp.504-515
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• 2008

유선 네트워크의 빠른 전송속도 및 다양한 서비스와 무선의 편리성 및 이동성이 결합되어 새로운 서비스 영역을 창출하고 사용자와 서비스 제공자 모두에게 새로운 변화를 가져올 신기술로 유/무선 통합 시대가 전개되고 있다. 유/무선 통합 서비스 중에서 네트워크의 통합은 이기종 네트워크간 연동에 의한 네트워크 융합과 네트워크상에서 전송기술간 융합으로써 매주 중요한 부분을 차지하고 있다. 이러한 상황 속에서 이기종 네트워크의 융합은 서로 다른 네트워크의 융합으로 인해 기존의 보안 기술 및 통신 기술을 그대로 적용하기가 매우 어려우며, 보안 측면에서도 많은 취약점을 내포하고 있다. 기존의 동종 네트워크에서 사용자의 인증 및 키 관리와는 다르게 이기종 네트워크간의 사용자 인증 및 키 관리는 새로운 기술이 필요한 실정이며 또한 동종 네트워크에서 이기종 디바이스간의 보안 기술 확립은 매우 중요한 사항이라 할 수 있다. 본 논문에서는 이기종 네트워크 환경에서의 안전하고 효율적인 키 관리를 제안하여, 이기종 네트워크 디바이스간의 안전한 통신을 제공 할 수 있다.

• 한국시뮬레이션학회논문지
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• 제15권3호
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• pp.1-9
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• 2006

현재 그리드 컴퓨팅은 네트워크 컴퓨팅 환경에서 대용량의 데이터와 엄청난 컴퓨팅의 문제를 해결하는데 매우 효과적인 해결책으로 각광받고 있다. 그리드는 애플리케이션을 여러 부분으로 나누어, 각 부분을 수많은 컴퓨터에서 동시에 수행함으로써 대규모 시뮬레이션 및 대용량 컴퓨팅을 실현할 수 있다. 그러나, 이를 위해서는 효과적인 자원 관리와 스케줄링 기법이 필요하다. 이 논문에서 우리는 분산된 그리드 컴퓨팅 환경에서의 자원관리와 스케줄링에 적용 가능한 그리드 거래망 모델을 제안하고 자율적인 자원 거래를 위한 가격 입찰 알고리즘을 소개한다. 우리는 모델의 효율성과 능력을 입증하기 위해 DEVSJAVA 모델링 & 시뮬레이션 환경 하에서 프로토타입 모델을 설계하고 실험하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제9권4호
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• pp.59-66
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• 2017

Cloud computing has evolved into a core computing infrastructure for the internet that encompasses content, as well as communications, applications and commerce. By providing powerful computing and communications capabilities in the palm of the hand everywhere with a variety of smart devices, mobile applications such as virtual reality, sensing and navigation have emerged and radically changed the patterns people live. The data that is generated is getting bigger. Cloud computing, on the other hand, has problems with system load and speed due to the collection, processing and control of remote data. To solve this problem, fog computing has been proposed in which data is collected and processed at an edge. In this paper, we propose a system that dynamically selects a fog server that acts as a cloud in the edge. It serves as a mediator in the cloud, and provides information on the services and systems belonging to the cloud to the mobile device so that the mobile device can act as a fog. When the role of the fog system is complete, we provide it to the cloud to virtualize the fog. The heterogeneous problem of data of mobile nodes can be solved by using mDBaaS (Mobile DataBase as a Service) and we propose a system design method for this.

• Journal of Multimedia Information System
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• 제2권1호
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• pp.153-162
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• 2015

In today's pervasive computing environments, multimedia content should be adapted to meet various conditions of network connections, terminals, and user characteristics. Scalable Video Coding (SVC) is a key solution for video communication over heterogeneous networks, where user terminals have different capabilities. This paper presents a standard-compliant approach that adapts an SVC bitstream to support multiple users. The adaptation problem is formulated as an optimization problem, focusing on the tradeoff between qualities of different spatial layers of an SVC video. Then the adaptation process is represented by standard metadata of MPEG-21, which can be solved by universal processing to enable interoperable and automatic operation. Our approach provides the users with optimal quality, a wide flexibility, and seamless adaptation. To the best of our knowledge, this is the first study that shows the adaptation tradeoff between spatial layers of a conforming SVC bitstream.

• Journal of Computing Science and Engineering
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• 제10권1호
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• pp.9-20
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• 2016

Several task clustering heuristics are proposed for allocating tasks in heterogeneous systems to achieve a good response time in data intensive jobs. However, one of the challenging problems is the process in task scheduling after task allocation by task clustering. We propose a task scheduling method after task clustering, leveraging worst schedule length (WSL) as an upper bound of the schedule length. In our proposed method, a task in a WSL sequence is scheduled preferentially to make the WSL smaller. Experimental results by simulation show that the response time is improved in several task clustering heuristics. In particular, our proposed scheduling method with the task clustering outperforms conventional list-based task scheduling methods.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.225-232
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• 2014

The traditional RAP (Redundancy Allocation Problem) of complex systems has considered only the redundancy of subsystem with homogeneous components. In this paper we extend it as a RAP of complex systems with heterogeneous components which is more flexible than the case of homogeneous components. We model this problem as a nonlinear integer programming problem, find its optimal solution by tabu search, and suggest an example of the efficient reliability design with heterogeneous components. In order to improve the quality of the solution of the tabu search, we suggest a modified tabu search to employ an adaptive procedure (1-opt or 2-opt exchange) to generate the efficient neighborhood solutions. Computational results show that our modified procedure obtains better solutions as the size of problem increases from 30 to 50, even though it requires rather more computing time. With some adjustment of the parameters of the proposed method, it can be applied to the optimal reliability designs of complex systems of ships.

• 한국CDE학회논문집
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• 제5권1호
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• pp.61-70
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• 2000

The design and development of a Web-based Workflow Management System (WfMS) is described in this paper. WfMSs are employed by many organizations to manage their business processes efficiently. The goal of this research is to provide an effective management of design processes in a distributed and heterogeneous environment-an environment in which workflow participants are geographically dispersed and use different computing platforms. We identify the requirements of WfMSs for the distributed and heterogeneous environment. We present an approach to applying the Web technology to was. The developed system is composed of three main modules: Worflow Engine, Web-based clients, and Process Designer. The workflow engine is implemented in pure Java for portability to heterogeneous platforms. furthermore, the client interfaces are all programmed using applets, and thus they can be readily accessed through the Internet/intranet. The Process Designer provides a build-time function of generating process specifications. Some important functions of the developed system are explained in this paper. A prototype system has been developed and applied to design processes. The system allows effective cooperation among designers who may be geographically separated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3231-3244
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• 2016

As processor design has been transiting from homogeneous multicore processor to heterogeneous multicore processor, traditional Amdahl's law cannot meet the new challenges for asymmetric multicore system. In order to further investigate the impact factors related to the Overhead of Data Preparation (ODP) for Asymmetric multicore systems, we evaluate an asymmetric multicore system built with CPU-GPU by measuring the overheads of memory transfer, computing kernel, cache missing and synchronization. This paper demonstrates that decreasing the overhead of data preparation is a promising approach to improve the whole performance of heterogeneous system.

• 인터넷정보학회논문지
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• 제10권2호
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• pp.143-151
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• 2009

본 논문에서는 유무선 혼합 네트워크상에서 TCP 스킴을 평가하기 위해 굿풋, 굿풋 인덱스, 정규화된 굿풋 인덱스 등을 정의하였다. 이러한 메트릭스들은 주로 TCP 스킴을 측정하기 위해 사용된 성능 메트릭스와는 달리 주어진 네트워크 상황에서 목적을 달성할 수 있는 능력인 성취도 개념을 포함하고 있다.

• 한국멀티미디어학회논문지
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• 제22권7호
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• pp.759-769
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• 2019

Since a surgery simulation should be able to represent the internal structure of the human body, it is advantageous to adopt volume based techniques rather than polygon based techniques. However, the volume based techniques induce large computation to deform heterogeneous volume datasets such as bones and muscles. In this study, we propose a new method to deform volume data using multi-core CPUs. By improving previous studies, the proposed method minimizes unnecessary propagation operations. Moreover, we propose an efficient task-partitioning method for volume deformation using multi-core CPUs. As a result, we can simulate the deformation of heterogeneous volume data at an interactive speed without special hardware.