• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.597-604
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• 2002

Changing group key is necessary for the remaining members when a new member joins or a member leaves the group in multicast communications. It is required to guarantee perfect forward and backward confidentiality. Unfortunately, in large groups with frequent membership changes, key changes become the primary bottleneck for scalable group. In this paper, we propose a novel approach for providing efficient group key distribution in large and dynamic groups. Unlike existing secure multicast protocols, our protocol is scalable to large groups because both the frequency and computational overhead of re-keying is determined by the size of a subgroup instead of the size of the whole group, and offers mechanism to prevent the subgroup managers with group access control from having any access to the multicast data that are transfered by sender. It also provides security service for preserving privacy in wireless computing environments.

• Information and Communications Magazine
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• v.11 no.6
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• pp.37-54
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• 1994

Technical innovation on multimedia data processing brings us new multimedia services. Multimedia services are classified into five groups : TVs, computers, telecommunications, periperals, and softwares. This paper surveys on the services in various aspects and, in particular, computer areas are discussed in detail. To provide the services, major subsystems such as highspeed networks, operating systems, intelligent agent based user interfaces are discussed. In particular, multimedia operating systems are the most actively investigating research area as an infrastructure of multimedia computer systems to provide integrated multimedia services. So, the trends of new multimedia operating systems are analyzed and COSMOS (Collaborative Object Sharing for Multimedia Operating System) multimedia group presentation is discussed. The characteristics, model and abstract data structure of COSMOS is described. The performance analysis of 3 person conference system using audio, video and shared graphic editor on COSMOS shows that taking integrated multimedia operating system approach leads changing of new multimedia service environments.

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.1-8
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• 2017

Lightweight Encryption Algorithm(LEA) was developed by National Security Research Institute(NSRI) in 2013 and targeted to be suitable for environments for big data processing, cloud service, and mobile. LEA specifies the 128-bit message block size and 128-, 192-, and 256-bit key sizes. In this paper, block cipher LEA algorithm which can encrypt and decrypt 128-bit messages is designed using Verilog-HDL. The designed IP for encryption and decryption has a maximum throughput of 874Mbps in 128-bit key mode and that of 749Mbps in 192 and 656Mbps in 256-bit key modes on Xilinx Vertex5. The cryptographic IP of this paper is applicable as security module of the mobile areas such as smart card, internet banking, e-commerce and IoT.

• Journal of Information Management
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• v.39 no.4
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• pp.97-120
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• 2008

Evaluation indicators reflecting recent digital environments are needed as a tool to increase research library's competitiveness and productivity. Especially, research libraries have different subject backgrounds and there are many one-person libraries. In this study, we developed new evaluation indicators based on the draft indicators made in 2007 considering these environmental elements so that it may be used easily and applicable to various research libraries. In developing the new indicators, we reviewed other library type's indicators and listened carefully to the comments from expert librarians in the research libraries through several meetings. After developing the indicators, we made a survey in order to verify its validity as well as its effectiveness and also made a test evaluation for research libraries. The proposed indicators will contribute in evaluating the current level of Korean research libraries and promoting them to the future-oriented libraries.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.223-231
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• 2015

This paper proposes a new wireless backhaul technology based on MHN(Mobile Hotspot Network) which uses a wide frequency band of millimeter wave to provide wideband Wi-Fi services for subway passengers. Performance analysis of MHN up and down links, based on data: up and down links structure analysis of physical layer and simulation study of the MHN wireless backhaul link model, show that the proposed MHN-based wireless backhaul network can transmit data at a 1.2Gbps data rate and provide Internet service 100 times faster than that of conventional WiBro-based wireless backhaul networks. These results indicate that the proposed MHN technology is appropriate for subway mobile networks.

• Journal of Digital Contents Society
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• v.16 no.6
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• pp.917-925
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• 2015

WebRTC is one of the most recent technologies that supports browser-to-browser for voice calling, video chat, and P2P file sharing without the need of either internal or external plugins. However, there has some limitation which lets our development deal with many problems. This research will focus just on a small field of that problem which is bandwidth. While the bandwidth for downloading and uploading is fixed by service providers, but the number of users in a certain area is increasing largely by the time. In this paper, we propose a model to overcome the limitation of the bandwidth based on fuzzy control to adjust utilized bandwidth by changing frame rate and resolution of streaming video in the client itself.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.139-147
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• 2016

Korea is ahead of the launch of internet banking professional following to America, Europe and Japan. Internet banking is a professional non-store bank to conduct business such as deposits and loans on the internet and call centers. It is operating in a low-cost structure and minimizes the loans and deposits, various fees than traditional banks and obtains a profit. In order to be successful internet banking professional to develop a differentiated work with the existing banks should be competitive. In this paper, we explore and analyze the cases of Japan and the United States to present the future direction of domestic Internet banking professional future. Also it is expected to enable faster and more convenient one-stop financial services. Internet specialized bank is expected to continue to develop further by the inevitable competition with conventional banks as developing differentiated financial services. Deregulation of banks and industries and participation of various companies of security, insurance, telecommunications, and retail are expected to lead to the convergence among industries and development of new financial services.

• Journal of Intelligence and Information Systems
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• v.19 no.4
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• pp.11-20
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• 2013

In designing Intelligent Traffic Systems, it should be necessary to consider telecommunications, appearance, environment, auxiliary functions, safety, and so on. Also, in choosing a car, a consumer considers those properties. This paper tried to elucidate the fact that car color has a very significant meaning for car safety when administrating intelligent traffic services and making car-purchasing decision. We first studied on occurrence probability of car accident according to car color that has something to do with car safety. Then, we studied on the concepts of advancing color and receding color. Advancing color causes less accidents since the color looks closer than it actually is. And receding color causes more accidents since the color looks farther than it actually is. And we classified car colors into eight classes and assign their ranking to each class, considering the number of car accidents. We tried to verify our research by use of telephone questionnaire for residents in Kunsan, Republic of Korea.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1522-1533
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• 1996

This paper presents a programming environment for the edition and verification of specification language SDL. It is implemented in the Concerto software factory, which has been as a support for the development of real size software. Concerto is a software factory designed for application development in the fields of computer communication protocols or real time system. It offers various kinds of tools to produce software, organize this production and automate it. Concerto allows a smooth integration of various formalism such as the C and $C^{++}$, languages, structured documentation, HOOD methodology (Hierarchical Object Orient Design). In this paper, as an important tools in the process of communication protocol software development, we describe fist describe the principles of this environment, then we illustrate its application by means of a simple example, the Inres protocol. Moreover, we study how hypertext mechanism of Concert to create logical links between a protocol and its asscoiated service.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.411-422
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• 2017

Current policies for sharing bandwidth increase average throughput and improve utilization of the bandwidth in the local network. However, with these policies, a central administer, which is responsible for allocating bandwidth to each network flow, cannot allocate resources based on user characteristics. Thus, it leads to unfair bandwidth allocation because it does not guarantee services based on user characteristics. Therefore, we propose a novel negotiation method to share the bandwidth in a limited bandwidth network, in which, a user negotiates with other users to gain more resource. Ideally, we use a fuzzy system to infer and determine whether a device will request bandwidth or not based on the current usage of the given device. We conduct two experiments consisting of a video streaming simulation in OPNET and a real-time video streaming in WebRTC. The results of the experiment indicate that the proposed method can flexibly share the bandwidth utilization based on user's requirement in the network.