• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.6
• /
• pp.672-677
• /
• 2016

Development of Internet has been successfully inspired with extensive deployment of the network technology and application. However, increases in Internet usage had caused a lot of traffic overload in these days. Thus, we need a continuous research and development on the network virtualization for effective resource allocation. In this paper, we propose a minimal cost virtual network mapping algorithm using Piecewise Linear Cost Function. We exploited an algorithm with Linear Programming and D-VINE for node mapping, and Shortest Path Algorithm based on linear programming solution is used for link mapping. In this way, we compared and analyzed the average cost for arrival rate of VN request with linear and tree structure. Simulation results show that the average cost of our algorithm shows better efficiency than ViNEyard.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.11
• /
• pp.1011-1022
• /
• 2014

Currently, the wireless network environment of air node is constructed mainly of ground relay station. However, as the Korean Peninsula is composed of 70% mountainous region, there are multiple shadow zones. This is calling for effective measures to prevent aircraft from losing communication link during low-mid altitude missions. In this article we propose the utilization of Bezier Curve for estimation of aircraft flight path and control method for entering shadow zone. This method successfully estimated aircraft track, and analyzed the existence, disseminated the warning, and took measures to avoid the shadow zone before entering. This article, suggested after simulated experiments, proves that the method enables seamless communication during air operations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.10
• /
• pp.909-916
• /
• 2016

The beacon receiver is an equipment which detects and measures the signal strength of transmitting satellite beacon signal. Beacon signals transmitted by satellites are low power continuous wave(CW) signals without any modulation intended for antenna steering to satellite direction and power control purposes on the earth. The beacon signal detection method using a very narrow band analog filter and RSSI(Received Signal Strength Intensity) has been typically used. However, it requires the implementation to track the frequency at the beacon receiver, thus a beacon frequency variation of the satellite due to temperature changes and long-term operation. Therefore, in this paper, the beacon signal detection receiver is designed by using a very narrow band digital filter array for a faster acquisition and SNR(Signal to Noise Ratio) method detection. For this purpose, by calculating the satellite link budget with the rain attenuation between satellite and ground station, and then extracting the received $C/N_o$ of the beacon signal, this work derives the bandwidth and the array number of the configured digital filter that gives the required C/N.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.517-520
• /
• 2005

Wireless sensor network combines sensing and computing technology which can sense light, temperature, vibration, magnetic field and wind etc, as each purpose of using those. Wireless nodes operate signal processing skill which has proceeded sensed information from the sensor, transmission which makes information reached to observer and limited energy managing skill which is needed on account of using battery to operate wireless. To make responsible measuring and sensing out of them, efficient energy management is so important to maintain life time of network. In this paper, after explaining CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance) traditional wireless MAC protocol, and ER-MAC(Energy Rate Medium Access Control) which are not managing resource of hardware but MAN(Medium Access Control), data-link layer out of OSI 7 layer. We would like to analyze those efficiency of power saving comparing with each protocol.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.9B
• /
• pp.760-773
• /
• 2003

The Internet is evolving from best-effort service toward an integrated or differentiated service framework with quality-of-service (QoS) assurances that are required for new multimedia service applications. Given this increasing demand for high bandwidth Internet with QoS assurances in the coming years, an IP/MPLS-based control plane combined. with a wavelength-routed dense-wavelength division multiplexing (DWDM) optical network is seen as a very promising approach for the realization of future re-configurable transport networks. This paper proposes a differentiated lambda establishment process for QoS guarantees based on the differentiated MPLS service (DMS) model. According to the QoS characteristics of wavelength in optical links and the type of used Optical Cross-Connect (OXC) nodes in DWDM next generation optical Internet backbone network, a differentiated wavelength assignment strategy that considers QoS recovery capability is also suggested.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.2
• /
• pp.189-197
• /
• 2016

Mobile ad-hoc networks (MANETs) experience frequent link disconnections due to non-uniform node distribution and mobility. Thus, end-to-end path establishment-based routing protocols cause frequent transmission failures in MANETs, resulting in heavy control messages for path reestablishment. While location-based MANET routing protocols, such as Greedy Perimeter Stateless Routing (GPSR), use location information to forward messages in a hop-by-hop routing fashion without an end-to-end path establishment procedure, such protocols encounter communication void problems when message forwarding to the next hop fails due to the absence of a relay node. Therefore, to solve this problem, this paper proposes a Delay Tolerant-GPSR (DT-GPSR) protocol, which combines Delay Tolerant Networking (DTN) technology with the GPSR protocol. The performance of DT-GPSR is compared with the performances of the original GPSR and PRoPHET routing protocols through simulation using NS-2. The simulation results confirm that DT-GPSR outperforms GPSR and PRoPHET in terms of the message delivery ratio and message delivery delay.

• Journal of Broadcast Engineering
• /
• v.13 no.2
• /
• pp.245-250
• /
• 2008

Efficient service discovery mechanism is a crucial feature for the usability of a wireless ad-hoc network. A wireless ad-hoc network is a temporal network formed by a collection of wireless mobile nodes without the aid of any existing network infrastructure or centralized administration. We propose an efficient service discovery mechanism using non-disjoint multi-path routing protocol for a wireless ad-hoc network. Our scheme has advantages of not only multi-path routing protocol but also cross-layer service discovery. By simulation, we showed that faster route recovery is possible by maintaining multiple routing paths in each node, and the route maintenance overhead can be reduced by limiting the number of multiple routing paths and by maintaining link/node non-disjoint multi-path.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.522-525
• /
• 2006

Recently, mobile devices support multi-functions such as 3D game, wireless internet, moving pictures, DMB, GPS, and PMP. Bigger size of display device is indispensable to support these functions and higher speed of the interface is needed. However, conventional parallel interfaces between processor and display nodule are not competent enough for that high speed transfers. High-speed serial interface is beginning to appear as an alternative for parallel interface. The advantages of the serial interface are high bandwidth, small number of interconnections, low-power consumption, and good quality of electro-magnetic interference. In this paper, we implement serial interface and use it for a display module. LVDS is used for PHY layer and a defined packet is used for link layer. The feature of the implemented serial interface is the reduced number of interconnections with enough bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.3
• /
• pp.506-512
• /
• 2018

Unmanned aerial vehicles(UAVs) operating in the military for various purposes are designed to transmit information collected according to the purpose to GCS(Ground Control System), and to transmit/receive the vehicle's operational control and status information using wireless communication(or datalink). Currently, the military UAV systems in operation in Korea use unique communication methods, protocols, and message structures for each system. Among these, the Division UAV is designed to transmit fixed size TM/TC data repeatedly and the Corps UAV is designed to transmit aperiodic TM/TC data to the variable length of the message-based. In this paper, we analyze the TM/TC data protocol of existing military UAV systems and present data protocol design method which is considered to be more efficient in wireless communication environment applied to equipment under development. And we will discuss issues to be considered for standardization of technology for ensuring interoperability with many UAVs or newly introduced UAV systems.

• Journal of Information Management
• /
• v.40 no.1
• /
• pp.29-46
• /
• 2009

Theses and Dissertation(TD) have been considered one of valuable scholarly resources, while there have existed some limitations to collect, organize, and provide them. The purpose of this study is to investigate users' perception on six TD services from five institutions and to propose improvement strategies. Six TD services includes National Library, National Assembly Library, RISS, dCollections, NDSL, and Council of Theses and Dissertation Common Use. Based on the survey results from 151 users, the findings of this study identified that National Assembly Library and RISS were preferred by users. In addition, users preferred keyword, full text, department, abstract, table of contents, as well as title and author over other bibliographic information. More importantly, users needs were placed on whether specific TD services provide full text or not. In case that is not possible to provide full text, users have a preference for full text link information. As a result, in order to improve the TD services, service promotion activities, diverse access points, and full text provision are desirable.