• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.609-610
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• 2017

Cognitive radio communication techniques have been attracting attention to efficiently use the scarce spectrum as the wireless communication service increases. In cognitive radio communication, efforts to minimize interference to the primary user are important technical factors. In a multi-hop wireless ad hoc network, multi-hop transmission requires path and channel selection considering channel interference as well as collision with primary users. In the multi-channel environment, cognitive radio network has different capacities depending on the inter-channel interference and collision with the main users. In this paper, we propose a multi-hop transmission scheme that minimizes inter-channel interference and reduce collision with primary users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2703-2709
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• 2015

IT convergence with agriculture is expected to bring more efficiency and quality improvement in producing, distributing, consuming of agricultural products with the aid of information processing and autonomous control technologies of the IT area. Smart Farming based on network is a service which is capable of coping with environmental and technical problems with the actualized IT convergence case for agriculture. In this paper, it is required to consider the actualized IT convergence case for agriculture, namely Smart Farming as a solution to cope the presented problems. In addition, propose and suggest to standard model and standardization items requirement for the Smart Farming based on network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4724-4747
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• 2016

To efficiently reduce on-grid energy consumption, the admission control algorithm in the hybrid energy powered cellular network (HybE-Net) with base stations (BSs) powered by on-grid energy and solar energy is studied. In HybE-Net, the fluctuation of solar energy harvesting and energy consumption may result in the imbalance of solar energy utilization among BSs, i.e., some BSs may be surplus in solar energy, while others may maintain operation with on-grid energy supply. Obviously, it makes solar energy not completely useable, and on-grid energy cannot be reduced at capacity. Thus, how to control user admission to improve solar energy utilization and to reduce on-grid energy consumption is a great challenge. Motivated by this, we first model the energy flow behavior by using stochastic queue model, and dynamic energy characteristics are analyzed mathematically. Then, fuzzy logic based admission control algorithm is proposed, which comprehensively considers admission judgment parameters, e.g., transmission rate, bandwidth, energy state of BSs. Moreover, the index of solar energy utilization balancing is proposed to improve the balance of energy utilization among different BSs in the proposed algorithm. Finally, simulation results demonstrate that the proposed algorithm performs excellently in improving solar energy utilization and reducing on-grid energy consumption of the HybE-Net.

• Journal of the Korean Society for Library and Information Science
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• v.37 no.2
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• pp.153-168
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• 2003

A hyperlink on academic World Wide Web has started to be recognized as a form of collaborative communication network connecting individual researchers and research groups and expanding their collaboration relations by making possible easy and direct online contact among people or groups anywhere in the world. This paper describes the structure of academic hyperlinks embedded in universities' Web sites hosted at the 10 Asian countries and further, examines the association between the structure of the hyperlink network and collaborative communication pattern among those countries based on their frequency of co-authoring articles. This research found that the number of inter-hyperlinks among universities' Web sites was significantly correlated with the frequency of co-authored articles across the 10 countries.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.430-435
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• 2007

In this paper, we propose an intelligent deployment of sensor network for reliable communication. The proposed method determines optimal transmission range based on the wireless channel characteristics, and searches the optimal number of sensor nodes, and optimal locations with SOFM. We calculate PRR against a distance uses the log-normal path loss model, and decide the communication range of sensor node from PRR. In order to verify the effectiveness of the proposed method, we performed simulations on the searching for intelligent deployment and checking for link condition of sensor network.

• Annual Conference of KIPS
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• 2012.11a
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• pp.715-717
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• 2012

최근 대용량 모바일 트래픽을 효율적으로 처리하고 다양한 5세대 지식 서비스를 제공할 수 있는 차세대 이동통신 기술개발을 목표로 중추 네트워크라는 개념이 고려되고 있다. 중추 네트워크에서는 시스템 용량을 기존 이동통신 시스템 대비 크게 증대시키기 위하여 밀리미터파 대역에서 넓은 대역폭을 사용하고 빔형성 기술을 통하여 무선자원을 재사용한다. 그러나 밀리미터파 대역은 직진성이 매우 강하기 때문에 비가시거리 통신영역에서 통신 품질이 급격히 저하되는 문제점이 발생하며, 이를 해결하기 위해 중추 네트워크에서는 적절한 위치에 중계기를 설치하여 비가시거리 통신영역을 최소화하는 것을 고려한다. 본 연구에서는 기지국 및 중계기 위치에 따른 중추 네트워크의 성능을 분석하기 위해 개발된 시스템 레벨 시뮬레이터를 소개한다. 본 시뮬레이터는 중추 네트워크의 통신영역과 채널용량을 분석 및 연구하는데 크게 기여할 수 있을 것으로 기대된다.

• Journal of electromagnetic engineering and science
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• v.19 no.1
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• pp.20-30
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• 2019

A wide-band multiple-input multiple-output (MIMO) antenna with dual-band (2.4 and 5 GHz) operation is proposed for premium indoor access points (IAPs). Typically, an omni-directional pattern is used for dipole antennas and a directional radiation pattern is used for patch antennas. In this paper, both antenna types were used to compare their performance with that of the proposed $2{\times}2$ MIMO antenna. We simulated and measured the performance of the MIMO antenna, including the isolation, envelope correlation coefficient (ECC), mean effective gain (MEG) for the IAPs, and the throughput, in order to determine its communication quality. The performance of the antennas was analyzed according to the ECC and MEG. The proposed antenna has sufficient performance and excellent characteristics, making it suitable for IAPs. We analyzed the communication performance of wireless networks using the throughput data of a typical office environment. The network throughput of an 802.11n device was used for the comparison and was conducted according to the antenna type. The results showed that the values of the ECC, MEG, and the throughput have unique characteristics in terms of their directivity, antenna gains, isolation, etc. This paper also discusses the communication performance of various aspects of MIMO in multipath situations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.200-201
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• 2016

Recently, according to era of Internet of Things was opened, various mobile devices connected to the internet using wireless communication. Many IoT devices have limited communication performance. Thus, these devices efficiently forward data using an abbreviated ID method. However, movement of devices causes abbreviated ID confliction, and These conflict degraded network performance. Therefore it is important management of ID conflict. In this paper, we proposed an abbreviated ID conflict management method to improve the efficiency of communication in the dynamic IoT network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.13-19
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• 2019

SDN is one of the most actively researched topics to solve traffic problems in communication. SDN implements multiple networks in a single physical network by virtualizing network resources through an advanced API. Network Function Virtualized (NFV) distributes network functions from hardware using software instant, virtualization technology to VNF. These features make network management easier and improve performance by virtualizing IP, routers, and so on. In this paper, we propose a method to control the traffic and provide the distributed controller effect of SDN through SDN distribution in the virtualized industrial network. It is expected that SDN distribution will be able to manage traffic more efficiently when using the proposed scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1298-1310
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• 2019

Network coding (NC) is a promising technology that can improve available bandwidth and packet throughput in wireless sensor networks (WSNs). Sliding window is an improved technology of NC, which is a supplement of TCP/IP technology and can improve data throughput and network lifetime on WSNs. This paper proposes a network coding-based maximum lifetime algorithm for sliding window in WSNs (NC-MLSW) which improves the throughput and network lifetime in WSN. The packets on the source node are sent on the WSNs. The intermediate node encodes the received original packet and forwards the newly encoded packet to the next node. Finally, the destination node decodes the received encoded data packet and recovers the original packet. The performance of the NC-MLSW algorithm is studied using NS2 simulation software and the network packet throughput, network lifetime and data packet loss rate were evaluated. The simulations experiment results show that the NC-MLSW algorithm can obviously improve the network packet throughput and network lifetime.