• 한국콘텐츠학회논문지
• /
• 제6권3호
• /
• pp.28-37
• /
• 2006

인터넷 기술은 지난 30여 년간 비약적으로 발전하여 모든 산업분야를 변혁시키고 개인과 기업의 필수도 구로서 국가의 중요한 기반시설로 자리 잡았다. 1990년대 중반부터 선진국들은 인터넷을 과학 및 교육 분야의 발전에 가장 중요한 기반시설의 하나로 인식하고 국가 연구 교육망을 구축하고 이를 새로운 망 기술과 과학 기술 개발을 위한 도구로 제공하고 있다. 이 논문에서 우리는 선진국의 연구 교육망 발전 현황을 종합적으로 살펴보고, 국내 첨단망 활동을 선진국과 비교하여 문제점 분석하고, 이를 토대로 한국 첨단망의 발전 방안을 제시하였다.

• Journal of Communications and Networks
• /
• 제18권4호
• /
• pp.610-618
• /
• 2016

A green cognitive radio network (CRN), characterized by base stations (BSs) that conserve energy during sleep periods, is a promising candidate for realizing more efficient spectrum allocation. To improve the spectrum efficiency and achieve greener communication in wireless applications, we consider CRNs with an long term evolution advanced (LTE-A) structure and propose a novel energy-saving strategy. By establishing a type of preemptive priority queueing model with a single vacation, we capture the stochastic behavior of the proposed strategy. Using the method of matrix geometric solutions, we derive the performance measures in terms of the average latency of secondary user (SU) packets and the energy-saving degree of BSs. Furthermore, we provide numerical results to demonstrate the influence of the sleeping parameter on the system performance. Finally, we compare the Nash equilibrium behavior and social optimization behavior of the proposed strategy to present a pricing policy for SU packets.

• ETRI Journal
• /
• 제20권1호
• /
• pp.1-15
• /
• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권11호
• /
• pp.5264-5281
• /
• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• International Journal of Advanced Culture Technology
• /
• 제6권2호
• /
• pp.58-64
• /
• 2018

This main purpose of the study is to identify social network of communicators sharing information on Bokjiro for publicizing welfare policy. This study employs NodeXL pro to understand networks and their role in the social network. The data for social network analysis was collected from Twitter for a week. The result of the analysis shows that the social network of communicators on Bokjiro does not have many nodes. It also has an independent network with high possibility of information distortion. Little communicators have controlling power in information flow in one way of communication. According to the result, it is not effective for marketing strategy of welfare policy in providing online information through Bokjiro. The study suggests that the government should use the transactional approach to marketing based on agent-oriented activity focusing on the exchange relationship between information providers and demanders in an age of networked intelligence.

• Journal of Communications and Networks
• /
• 제6권3호
• /
• pp.269-279
• /
• 2004

A new online multi-layer integrated routing (MLIR) scheme that combines IP (electrical) layer routing with WDM (optical) layer routing is investigated. It is a highly efficient and cost-effective routing scheme viable for the next generation integrated optical Internet. A new simplified weighted graph model for the integrated optical Internet consisted of optical routers with multi-granularity optical-electrical hybrid switching capability is firstly proposed. Then, based on the proposed graph model, we develop an online integrated routing scheme called differentiated weighted fair algorithm (DWFA) employing adaptive admission control (routing) strategies with the motivation of service/bandwidth differentiation, which can jointly solve multi-layer routing problem by simply applying the minimal weighted path computation algorithm. The major objective of DWFA is fourfold: 1) Quality of service (QoS) routing for traffic requests with various priorities; 2) blocking fairness for traffic requests with various bandwidth granularities; 3) adaptive routing according to the policy parameters from service provider; 4) lower computational complexity. Simulation results show that DWFA performs better than traditional overlay routing schemes such as optical-first-routing (OFR) and electrical-first-routing (EFR), in terms of traffic blocking ratio, traffic blocking fairness, average traffic logical hop counts, and global network resource utilization. It has been proved that the DWFA is a simple, comprehensive, and practical scheme of integrated routing in optical Internet for service providers.

• 한국항행학회논문지
• /
• 제13권1호
• /
• pp.54-61
• /
• 2009

본 논문에서는 디지털TV 방송전환시기와 이동통신사업자의 주파수 사용 허가 만료기간 등에 맞추어 700MHz, 800MHz 및 900MHz 대역 주파수에 대한 재분배계획 수립이 활발히 논의되고 있다. 이러한 주파수 재분배 정책방향은 800MHz(대역폭 10MHz) 통합지휘무선통신망 주파수에 대하여도 재분배가 거론 될 것으로 예상된다. 이러한 시점에 통합무선통신망을 구성하고 있는 주파수공용통신시스템인 TETRA시스템이 데이터통신 기능을 보강한 Release 2시스템에 대한 표준이 제시되고 있다. 이 시스템은 기존의 Release 1시스템보다 주파수대역의 소요가 최대 6배까지 증가되는 것으로 분석되고 있다. 따라서 통합지휘무선통신망에 할당된 현재의 주파수 대역으로는 이와 같이 발전된 시스템을 도입 할 수 없게 된다. 본 논문에서 디지털TV방송전환에 따른 정책동향을 분석을 토대로 700MHz대역에 대한 통합무선통신망용으로 할당에 대한 정책방향을 제시한다.

• 교통기술과정책
• /
• 제12권2호
• /
• pp.13-20
• /
• 2015

• Journal of Communications and Networks
• /
• 제18권4호
• /
• pp.540-550
• /
• 2016

Since energy efficiency has become a significant concern for network infrastructure, next-generation network devices are expected to have embedded advanced power management capabilities. However, how to effectively exploit the green capabilities is still a big challenge, especially given the high heterogeneity of devices and their internal architectures. In this paper, we introduce a hierarchical power management architecture (HPMA) which represents physical components whose power can be monitored and controlled at various levels of a device as entities. We use energy aware state (EAS) as the power management setting mode of each device entity. The power policy controller is capable of getting information on how many EASes of the entity are manageable inside a device, and setting a certain EAS configuration for the entity. We propose the optimal local control policy which aims to minimize the router power consumption while meeting the performance constraints. A first-order Markov chain is used to model the statistical features of the network traffic load. The dynamic EAS configuration problem is formulated as a Markov decision process and solved using a dynamic programming algorithm. In addition, we demonstrate a reference implementation of the HPMA and EAS concept in a NetFPGA frequency scaled router which has the ability of toggling among five operating frequency options and/or turning off unused Ethernet ports.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권9호
• /
• pp.3075-3093
• /
• 2014

In this paper, we consider an advanced wireless user, called primary-secondary user (PSU) who is capable of harvesting renewable energy and connecting to both the primary network and cognitive radio networks simultaneously. Recently, energy harvesting has received a great deal of attention from the research community and is a promising approach for maintaining long lifetime of users. On the other hand, the cognitive radio function allows the wireless user to access other primary networks in an opportunistic manner as secondary users in order to receive more throughput in the current time slot. Subsequently, in the paper we propose the channel access policy for a PSU with consideration of the energy harvesting, based on a Partially Observable Markov decision process (POMDP) in which the optimal action from the action set will be selected to maximize expected long-term throughput. The simulation results show that the proposed POMDP-based channel access scheme improves the throughput of PSU, but it requires more computations to make an action decision regarding channel access.