• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1253-1258
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• 2004

A general idea of implementing and managing real-time control on the VDN for rail transit vehicles is presented. In particular, the virtual device network considered in this paper is composed of Ethernet as the data network and LonWorks network as the device (control) network. A LonWorks/IP web server was used as a gateway to realize peer to peer data communication on the virtual device networks. Experimental results are given to validate the suggested architecture.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.257-258
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• 2019

본 논문에서는 "프로세서 중심 컴퓨터 구조"에서 개발된 MPI 병렬 프로그램을 수정하지 않고 "메모리 중심 컴퓨터 구조"에서 더 효율적으로 수행시키는 기술을 제안한다. 본 연구에서 제안하는 기술은 메모리 중심 컴퓨터 구조가 가지는 "빠른 대용량 공유 메모리" 특징을 이용하여 MPI 표준 라이브러리가 수행하는 네트워크 통신을 통한 느린 데이터 전달을 공유 메모리를 통한 빠른 데이터 전달로 대체하여 효율성을 얻는다. 본 연구에서 제안한 기술은 도커 가상화 기술을 사용한 분산 시스템 환경에서 MC-MPI-LIB 라이브러리 및 MC-MPI-SIM 시뮬레이터로 구현되었으며 다수의 MPI 병렬 프로그램으로 시험 수행하여 효율성이 있음을 보였다.

• The KIPS Transactions:PartA
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• v.14A no.4
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• pp.215-226
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• 2007

For past years, many distributed virtual shared-memory(DVSM) systems have been studied in order to develop a low-cost shared memory system with a fast interconnection network. But the DVSM needs a lot of data and control communication between distributed processing nodes in order to provide memory consistency in software, and this communication overhead significantly dominates the overall performance. In general, the communication overhead also increases as the number of processing nodes increase, so communication overhead is a very important performance factor for developing a large-scale DVSM system. In this paper, we study the performance scalability quantitatively and qualitatively for developing a large-scale DVSM system based on the next generation interconnection network, called the InfiniBand. Based on the study, we analyze a performance requirement of the next-coming interconnection network to be used for developing a performance-scalable DVSM system in the future.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2627-2640
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• 1998

In this paper, we analyze the performance of the virtual cell system[1] for the transmission of IP datagrams in mobile computer communications. A virtual cell consistsof a group of physical cells shose base stationsl are implemented b recote bridges and interconnected via high speed datagram packet switched networks. Host mobility is supported at the data link layer using the distributed hierachical location information of mobile hosts. Given mobility and communication ptems among physical cells, the problem of deploying virtual cells is equivalent to the optimization cost for the entire system where interclster communication is more expesive than intracluster communication[2]. Once an iptimal partitionof disjoint clusters is obtained, we deploy the virtual cell system according to the topology of the optimal partition such that each virtual cell correspods to a cluser. To analyze the performance of the virtual cell system, we adopt a BCMP open multipel class queueing network model. In addition to mobility and communication patterns, among physical cells, the topology of the virtual cell system is used to determine service transition probabilities of the queueing network model. With various system parameters, we conduct interesting sensitivity analyses to determine network design tradeoffs. The first application of the proposed model is to determine an adequate network bandwidth for base station networking such that the networks would not become an bottleneck. We also evaluate the network vlilization and system response time due to various types of messages. For instance, when the mobile hosts begin moving fast, the migration rate will be increased. This results of the performance analysis provide a good evidence in demonsratc the sysem effciency under different assumptions of mobility and communication patterns.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.61-67
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• 2018

Emulab software was developed by the team of University of Utah and it has been replicated at dozens of other sites in the world. Although KREONET Emulab, which established by the Korea Institute of Science and Technology Information, has only a modest number of compute nodes it has been provided an ideal playground to conduct various research for network protocols, cyber security and convergence research. A testbed is a critical enabler of experimental research and researchers only carry out the experiments that are supported by the testbed. This paper outlines the Utah Emulab's status and use types among the last 10 years of operation results and compares them with the ones with the KREONET Emulab. In addition, Testbed-as-a-Service(TaaS) is discussed to upgrade the testbed for the convergence research community services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.6
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• pp.379-386
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• 2014

Recently, middleboxes play a key role in many network settings such as firewalls, VPN gateways, proxies, intrusion detection and prevention systems, and WAN optimizers. However, achieving the performance and security benefits that middleboxes offer is highly complex, and therefore it is essential to manage middleboxes efficiently and dynamically. In this respect, Software-Defined Networking (SDN) offers a promising solution for middlebox policy enforcement by using logically centralized management, decoupling the data and control planes, and providing the ability to programmatically configure forwarding rules. Also, cloud computing and distributed Network Function Virtualization (NFV) can enable to manage middleboxes more easily. We introduce SDN-based middlebox management framework in integrated wired and wireless networks and discuss the further issues.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.11-21
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• 2015

If the cloud computing environment is not sufficiently provide the required resources due to the number of virtual server to process the request, may cause a problem that the load applied to the specific server. Migration administrator receive the resources of each physical server for improving the efficiency of the virtual server that exists in the physical servers, and determines the migration destination based on the simulation results. But, there is more overhead predicting the future resource consumption of all the physical server to decide the migration destination through the simulation process in large and complex cloud computing environments. To solve this problem, we propose an improved prediction method with the simulation-based approach. The proposed method is a fuzzy-logic based priority model for VM migration. We design a proposed model with the DEVS formalism. And we also measure and compare a performance and migration count with existing simulation-based migration method. FPLM shows high utilization.

• Journal of the Korean Society for information Management
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• v.38 no.3
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• pp.23-39
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• 2021

This study aims to explore research trends in Blockchain studies in South Korea using dynamic topic modeling and network analysis. To achieve this goal, we conducted the university & institute collaboration network analysis, the keyword co-occurrence network analysis, and times series topic analysis using dynamic topic modeling. Through the university & institute collaboration network analysis, we found major universities such as Soongsil University, Soonchunhyang University, Korea University, Korea Advanced Institute of Science and Technology (KAIST) and major institutes such as Ministry of National Defense, Korea Railroad Research Institute, Samil PricewaterhouseCoopers, Electronics and Telecommunications Research Institute that led collaborative research. Next, through the analysis of the keyword co-occurrence network, we found major research keywords including virtual assets (Cryptocurrency, Bitcoin, Ethereum, Virtual currency), blockchain technology (Distributed ledger, Distributed ledger technology), finance (Smart contract), and information security (Security, privacy, Personal information). Smart contracts showed the highest scores in all network centrality measures showing its importance in the field. Finally, through the time series topic analysis, we identified five major topics including blockchain technology, blockchain ecosystem, blockchain application 1 (trade, online voting, real estate), blockchain application 2 (food, tourism, distribution, media), and blockchain application 3 (economy, finance). Changes of topics were also investigated by exploring proportions of representative keywords for each topic. The study is the first of its kind to attempt to conduct university & institute collaboration networks analysis and dynamic topic modeling-based times series topic analysis for exploring research trends in Blockchain studies in South Korea. Our results can be used by government agencies, universities, and research institutes to develop effective strategies of promoting university & institutes collaboration and interdisciplinary research in the field.

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.45-51
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• 2021

In accordance with the rapid non-face-to-face environment and mobile first strategy, the explosive increase and creation of many structured/unstructured data every year demands new decision making and services using big data in all fields. However, there have been few reference cases of using the Hadoop Ecosystem, which uses the rapidly increasing big data every year to collect and load big data into a standard platform that can be applied in a practical environment, and then store and process well-established big data in a relational database. Therefore, in this study, after collecting unstructured data searched by keywords from social network services based on Hadoop 2.0 through three virtual machine servers in the Spring Framework environment, the collected unstructured data is loaded into Hadoop Distributed File System and HBase based on the loaded unstructured data, it was designed and implemented to store standardized big data in a relational database using a morpheme analyzer. In the future, research on clustering and classification and analysis using machine learning using Hive or Mahout for deep data analysis should be continued.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.607-616
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• 2008

By the advancement of computer & network technology, the paridigm of 'Network Computer' has been realizing`. In what is called network computer, computer system and computing resource is incomparably seem to be expanded compared with conventional network technology[1]. Network connected computer system consitute a massive virtual computer, it is possible for people to use an enourmous amout of computing resource distributed widely through the network. It is also possible that we make client lightweight by the use of computer system & all shared computing resources on the network in our computer processing and we call this type of client system as thin-client. Thin-client and network computer are on and the same network paradigm in that both paradigm featuring the active use of computer system and resource on the network[2]. In network computer paragem, network itself is regarded as a basic platform for the transfer of application, so it is possible that client access remote serve system to run remote applications through the network[3]. In this paper, we propose the system architecture for the implementation of network computer by the use of Web browser, X window system and Pyjamas. By the use of network computer proposed in this paper, it is possible for people to run application on the server system as if he run local application, and it is expected to improve the security and maintenance efficiency.