• ETRI Journal
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• v.36 no.2
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• pp.197-205
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• 2014

This paper proposes a novel framework for virtual content delivery networks (CDNs) based on cloud computing. The proposed framework aims to provide multimedia content delivery services customized for content providers by sharing virtual machines (VMs) in the Infrastructure-as-a-Service cloud, while fulfilling the service level agreement. Furthermore, it supports elastic virtual CDN services, which enables the capabilities of VMs to be scaled to encompass the dynamically changing resource demand of the aggregated virtual CDN services. For this, we provide the system architecture and relevant operations for the virtual CDNs and evaluate the performance based on a simulation.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.36-41
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• 2016

Visible Light Communication (VLC) using Light Emitting Diodes (LEDs) within the existing lighting infrastructure can reduce the implementation cost and may gain higher throughput than radio frequency (RF) or Infrared (IR) based wireless systems. Current indoor VLC systems may suffer from poor downlink resource allocation problems and small system throughput. To address these two issues, we propose an algorithm called a conflict graph scheduling (CGS) algorithm, including a conflict graph and a scheme that is based on the conflict graph. The conflict graph can ensure that users are able to transmit data without interference. The scheme considers the user fairness and system throughput, so that they both can get optimum values. Simulation results show that the proposed algorithm can guarantee significant improvement of system throughput under the premise of fairness.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.103-109
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• 2008

Many Internet application provide the PKI(public key infrastructure)-based service to provide authentication and message integrity. Several researchers proposed PKI-based p2p network framework. However, in the real world, the use of PKI is not suitable for peer to peer network, because the peer-to-peer network is an open and dynamic network. Moreover, currently there is no nation-to-nation interoperable certificate. In this paper, we designed reliable p2p file sharing application without public key infrastructure. To do this we propose reliable public key distribution mechanism to distribute public key safely without PKI infrastructure for two-tier super-peer architecture. In our system, each peer generates and distributes its public/private key pairs, and the public key is securely distributed without PKI. The proposed mechanism is safe against MITM attack. This mechanism can be applied various P2P applications such as file sharing, IPTV, distributed resource sharing and so on

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.5
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• pp.111-124
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• 2010

AMI (Advanced Metering Infrastructure) is a core infrastructure of Smart Grid, and is promoting in various country. Wireless network is considered for cost savings and operational efficiencies in AMI. But various security problems are expected in wireless networks of AMI, so we should solve these problems. In this paper, we suggest a wireless network of AMI by using Binary CDMA and security countermeasures of AMI wireless network. Proposed security architecture is using BSIM (Binary Subscriber Identity Module) to perform user authentication and key agreement for the encryption and decryption over radio network to reduce security threats.

• ETRI Journal
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• v.20 no.1
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• pp.1-15
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• 1998

The recent technological and industrial revolution dictates a new approach in constructing Korean Information Infrastructure. Lacking past data on the newly emerging markets, econometrics methodologies cannot accurately forecast future path of advanced networks, let alone dynamic impacts of public policies. In this paper, we have built a system dynamics model of the Korean Information Infrastructure and simulated diverse policy measures including market integration and government initiative in investment for experimenting their effectiveness. The most counterintuitive result of our research is that the market integration policy will facilitate CATV networks at an early stage until the year 2010, but will result in a diminished market size in the long run. With the system dynamics approach, we can enhance our understanding of the complex policy systems and get valuable insights through learning by modeling and simulation.

• TTA Journal
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• s.43
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• pp.129-149
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• 1996

본 고에서는 Global Information Infrastructure (GII) 구축을 위하여 국제 표준화기구인 ITU, ISO, IEC 간에 최근 활동현황에 대하여 소개한다. 이를 위해 지난 1996년 1월 17-19일간에 열린 Global Information Infrastructure (GII)를 위하여 ITU-T 내에 Joint Rapporteur Group(JRG)회의 결과와 1월 24-26일간에 열린 ISO/IEC/ITU International GII 세미나에서 논의된 주요 결과를 정리한다. 먼저 ITU-T JRG 회의는 차기 연구회기(1997년-2000년)동안에 GII 표준화 절차와 기술적인 이슈를 ITU-T SG13을 중심으로 모든 ITU-T 스터디 그룹이 나누어서 진행해야될 업무를 정리하는 것이며 이는 1996년 10월에 개최될 WTSC에 제출할 예정이다. 다음으로 ISO/IEC/ITU International GII 세미나는 GII와 관련된 ITU, ISO, IEC 소속의 약 100여개의 표준화 그룹이 모여서 국제적으로 효과적인 작업을 하기 위한 방안을 모색하기 위하여 개최된 세미나이다. 여기는 통신망 관련하여 ITU, 상위 데이터 서비스와 관련된 ISO, 그리고 가전기기 및 단말장치와 관련된 IEC가 공통의 정보 하부구조의 건설을 위하여 더 이상 각기 표준화를 진행해서는 안 된다는 인식을 바탕으로 한 것이다.

• Journal of Information Technology Applications and Management
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• v.22 no.3
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• pp.115-128
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• 2015

Although the telecommunications service industry has become a basic infrastructure component of the information and communication technology (ICT) industry, it is now losing its reputation as a cash cow due to achieving a saturation of service subscribers, especially in South Korea. With the exception of improving network speeds, network operators are experiencing difficulties in creating new innovations. Therefore, new innovations for the telecommunications service industry should be identified in conjunction with government policies for industry promotion. To examine the innovative capabilities of a specific industry, innovation system theories were used as a framework for research. However, existing innovation systems are limited with regard to explaining the openness of relationships and user participation which are general properties of the ICT industry. Moreover, as sources of innovative activity, additional values such as financial support and collaboration are more appropriate. This study presents a new innovation system based on innovation values. We analyze the telecommunications service industry and prioritize the importance of telecommunication policies within South Korea. An in-depth interview with experts based on the innovation system framework is conducted first. Next, innovation factors derived from the interview are applied within an analytic hierarchy process (AHP), leading to a prioritization of innovation factors for the telecommunications service industry.

• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.157-165
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• 2006

The Purpose of this study is to analyze telecommunications impacts on travel in a comprehensive system, considering demand, supply, costs, and land use. This study first Presents a conceptual model, considering causal relationships among travel, telecommunications, land use, economic activity, and socio-demographics. Then, based on the conceptual model, the aggregate causal relationships between telecommunications (local telephone calls, toll calls, and mobile phone subscribers) and travel (vehicle-miles traveled and number of transit Passengers) are explored in a comprehensive framework, using structural equation modeling of national time series data spanning 1950-2000 in the U.S. The model results suggest that as telecommunications demand increases, travel demand increases, and vice versa. Additionally. transportation infrastructure and land use significantly affect travel demand.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.389-396
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• 2007

The Global Navigation Satellite System (GNSS) becomes more important and is applied to various systems. Recently, the Galileo navigation system is being developed in Europe. Also, other countries like China, Japan and India are developing the global/regional navigation satellite system. As various global/regional navigation satellite systems are used, the navigation ground system gets more important for using the navigation system reasonably and efficiently. According to this trend, the technology of GNSS Ground Station (GGS) is developing in many fields. The one of purposes for this study is to develop the high precision receiver for GNSS sensor station and to provide ground infrastructure for better performance services on navigation system. In this study, we consider the configuration of GNSS Ground Station and analyze function of Monitoring and Control subsystem which is a part of GNSS Ground Station. We propose Monitoring and Control subsystem which contains the navigation software for GNSS Ground System to monitor and control equipments in GNSS Ground Station, to spread the applied field of navigation system, and to provide improved navigation information to user.

• ETRI Journal
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• v.42 no.5
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• pp.658-668
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• 2020

In edge computing, most procedures, including data collection, data processing, and service provision, are handled at edge nodes and not in the central cloud. This decreases the processing burden on the central cloud, enabling fast responses to end-device service requests in addition to reducing bandwidth consumption. However, edge nodes have restricted computing, storage, and energy resources to support computation-intensive tasks such as processing deep neural network (DNN) inference. In this study, we analyze the effect of models with single and multiple local exits on DNN inference in an edge-computing environment. Our test results show that a single-exit model performs better with respect to the number of local exited samples, inference accuracy, and inference latency than a multi-exit model at all exit points. These results signify that higher accuracy can be achieved with less computation when a single-exit model is adopted. In edge computing infrastructure, it is therefore more efficient to adopt a DNN model with only one or a few exit points to provide a fast and reliable inference service.