• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.275-284
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• 2009

Fast development of network technology and digitalization of various kinds of information are accelerating the convergence of between them. Accordingly, an environment for integrated service is needed, where users can be provided with various kinds of information such as voice, video, and text, using even different kinds of devices in heterogeneous networks for communication and broadcasting. In general, enablers integrate several functions to provide with various services in application layer based on IMS in BcN including even different kinds of networks. But in order to receiving convergence services, we must reason the environment of the user through the profiles of the networks and the devices and provide a suitable service to the user. In this paper, we will propose an efficient architecture and functions of a context-aware module which decides the appropriate services based on the profiles in the IMS enabler and its convergence service environments.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.59-64
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• 2006

The broadband power detector for power amplitude envelope detection of the direct-conversion Six-port output signal was designed and implemented in this paper. The power detector should be linearly operated to produce the linear amplitude and phase signal for input RF signals in required broadband frequency range. The power detector should be designed under conditions of matching circuit with low VSWR, which protect unbalanced phase signal from reflection signal due to mismatch between the output port of a six-port and the input port of a power detector. The designed power detectors, which were implemented in L-band with 50 ohm matching and Ku-band with multiple LC matching circuits and isolator, respectively, were analyzed in viewpoints of the utilization as a power detector of direct conversion Six-port. The dynamic range of designed power detectors were also measured and rvaluated as a power detector of Six-port circuit.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.981-985
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• 2006

Wibro is stand for Wireless Broadband Internet called as Portable Internet, Wireless Broadband Internet or Wireless High-Speed Internet. This provides hish-speed internet service anytime, anywhere, from anyone and device with seamless mobility and the band is located between Mobile phone and wireless LAN. Wibro service should support handover to maintain connection continuously in movement because the service is based on If system which is different from cellular system. Current Mitre Mobility system and general Mobile If system has got a problem of delayed speed and lost packets during handover. IETF protocol has been proposed for minimizing this problem and its standardization is under process, mainly focused on Mip4, Mip6 and Mipshop WG. This article studies and analyzes an effective method of minimizing handover delay to improve the problem of WiBro system and its revitalization & outlook.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.512-515
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• 2010

SIGINT(SIGnal INTelligence) includes several parameters intercepted by measurement and analysis of the RF(Radio frequency) signal from free space. One of the important parameters is frequency information. Expecially, in order to perform instantaneous frequency measurement of Radar and Missile seeker's RF signals, we use dedicated RF modules as a DFD(Digital Frequency Discriminator) to provide frequency information by measurement of the relative phase difference between signals via intended RF delay lines. It must measure and provide realtime based frequency information on short pulsed RF signal up to 100 nSec or less. This document proposes Ultra wideband DFD consisted of a RF input section of Wideband 4 channel RF delay line and correlator, a digital processing section to measure and provide frequency information from I/Q signal, and a frequency calibration section. Also, it will show design suitability based on test results measured under test condition of very short input pulse signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.13-18
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• 2015

This study presents the structure design of antenna to have the dual band characteristics in a desired frequency band through the structural modification of an antenna structure. For the experiment, a wideband crossed planar monopole antenna was used. The target frequency band was set to ISM 2.45GHz/5.8GHz. To give the properties, an additional antenna element was added to the crossed planar monopole antenna, which is a main body of the antenna. And then structural adjustment parameter was set to change the length(shape) of the antenna. Various simulations were conducted to find the dual band characteristics in the desired frequency band. The simulations brought forth the antenna bandwidth above the normal values for ISM 2.45GHz/5.8GHz. The structural adjustment parameter introduced in this study for structural modification of an antenna can be useful in developing an antenna featured with dual band(multiband) characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.847-852
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• 2003

Apertures and PBG(Photonic Band Gap) has been employed on the ground plane in the coupled line filter simultaneously. In order to observe the maximum bandwidth, we used the line gap 0.2mm which is can be made in our lab. Band-pass filter type is four-stage coupled strip line filter. Teflon has been used for the substrate ($\varepsilon$$\sub$r/=3.2). The center frequency and the bandwidth are 2.18GHz and 230MHz, respectively. The bandwidth is broaden from 230MHz to 310MHz (80Mhz, about 34.7%) by aperture effect and harmonic frequencies are suppressed to 20-30dB by PBG effect. So the harmonic frequencies have been suppressed by the PBG effect and the bandwidth are broaden by aperture effect.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1734-1741
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• 2007

In this paper, the Hybrid SC/MRC-2/4 method in which bit synchronization and phase synchronization were not required was applied to the orthogonal MC DS-CDMA system in which each normalized subcarrier interval and processing gain had the same value, respectively, and the direct sequence spread code of each subcarrier was orthogonal. In the broadband wireless system in which multi-carrier transmission was used, a Doppler frequency shift occurred, which was caused by the difference between the highest subcarrier frequency md the lowest subcarrier frequency. In order to complement phase error caused by the shift, the orthogonal MC DS-CDMA system was analyzed so that the receiving signal could be perfectly synchronized by adjusting the PLL gain suitable for the entire system. As a result of simulations, as the PLL gain was increased, the change in the intervals was close to the case of perfect synchronization however, it became less when the PLL gain reached more than a certain value. Therefore, by selecting a proper PLL gain suitable for the system the orthogonal MC DS-CDMA can be designed in which the Hybrid SC/MRC method is applied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.930-939
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• 2021

In recent years, the use of broadband bandwidth and redundant links for stable transmission in networks has resulted in excessive energy consumption and reduced transmission efficiency. In this paper, we propose an optimization algorithm that reduces the number of transmission links and minimizes transmission energy by removing redundant traffic in networks where traffic redundancy is allowed. The optimization algorithm proposed in this paper uses the meta-heuristic method using Tabu search algorithm. The proposed optimization algorithm minimizes transmission energy by designing a neighborhood generation method that efficiently routes overlapping traffic. The performance evaluation of the proposed optimization algorithm was performed in terms of the number of links used to transmit all traffic generated in the network and the transmission energy consumed. From the performance evaluation results, it was confirmed that the proposed algorithm is superior to other algorithms previously proposed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.173-178
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• 2019

To analyze the diffraction properties of optical signals by periodic blazed 2D diffraction gratings, Toeplitz dielectric tensor is first defined and formulated by 2D spatial Fourier expansions associated with asymmetric blazed grating profile. The characteristic modes in each layer is then based on eigenvalue problem, and the complete solution is found rigorously in terms of modal transmission-line theory (MTLT) to address the pertinent boundary-value problems. Toeplitz matrix of symmetric and sawtooth profiles is derived from that of asymmetric blazed grating profile, and the diffraction properties for each profile are numerically simulated. The numerical results reveal that the asymmetric and symmetric profiles behave as anti-reflection GMR filter while the sawtooth profile works better as anti-transmission one rather than anti-reflection filter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.540-542
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• 2014

The Universal Plug and Play (UPnP) specification permits networked devices to discover each other and to provide diverse services in the home network environment. Recently, new paradigms such as mobile connected computing, cloud-based service delivery, smart device content sharing, and Internet of Things (IoT) have emerged, but the home network based UPnP shows functional limitations in supporting such paradigms. To support them, the UPnP Forum has recently extended the capabilities of the existing UPnP, calling it UPnP+. In this paper, the UPnP Device Architecture V2.0 (UDA 2.0), which forms the basis of UPnP+, is presented. We present how UDA 2.0 enables the expansion of the home network to wide-area networks and non-IP device domains.