• 한국지능시스템학회논문지
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• 제23권6호
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• pp.487-493
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• 2013

스마트 기기의 보급 확대로 다양한 콘텐츠를 서비스하는 이동 단말기의 한정된 채널 할당 문제가 심화되고 있다. 이동통신망에서는 이동국에서 채널할당 요청이 있을 때 교환국에서 각 기지국에 속한 이동국에 채널을 할당한다. 이 때 한정된 채널을 효과적으로 할당하기 위한 다양한 방식들이 제안되고 있는데, 여기서는 하이브리드 채널 할당에 유전 알고리즘을 이용한 UHGA(Universal Hybrid Channel Assignment using Genetic Algorithm)이 농촌 지역이나 도심 지역과 같은 다양한 환경의 범용 망에 적용되어 효율성이 있음을 시뮬레이션을 통해 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.854-858
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• 1987

This paper considers impulsive noise which produce burst error in high speed(approx.160Kbps) data transmission like ISDN(Integrated Servise Digital Network) using PSTN(Public Switching Telephone Network). To begin with, we obtains the transfer function of subscriber line to calculate the variation of bandwidth when the gain of receiver is fixed and channel capacity of non-gaussian channel in upper-and lower bound, and evaluates the transmission capability. In this paper compares channel capacity bounds which obtains when probability density function of impulsive noise is Laplacian distribution function with impulsive noise generated by waveform synthesier.

• 한국경영과학회지
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• 제21권2호
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• pp.187-201
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• 1996

A distributed dynamic channel assignment is proposed and its performance is examined in a highway microcellular radio environment. In the two step ordered local packing (TOLP) scheme, channels are assigned on an ordered basis under cochannel utilization in congested microcell region. A selection criterion is employed to decide the cell from which a free channel is borrowed. Simulation results show that the proposed scheme outperforms existing methods is channel utilization and call blocking probabilities, especially under asymmetric call arrivals with a lower call switching requirement.

• Journal of Power Electronics
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• 제15권2호
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• pp.319-326
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• 2015

In this paper, a cost-effective single switch multi-channel LED (light emitting diode) driver is proposed. While conventional LED drivers require as many non-isolated DC/DC converters as the number of LED channels, the proposed LED driver needs only one power switch and several balancing capacitors instead of expensive non-isolated DC/DC converters. Therefore, the proposed driver features a simpler structure, with a lower cost and a higher efficiency. Because its power switch can be turned off under the zero current switching condition, it has very desirable advantages such as improved electromagnetic interference characteristics and high efficiency. Moreover, it uses only a small number of DC blocking capacitors with no additional active devices for the current balancing of multi-channel LEDs. As a result, the proposed driver exhibits high reliability and is cost effective. To confirm the validity of the proposed driver, a theoretical analysis is performed, and design considerations and experimental results obtained from a prototype that is applicable to a 46" LED-TV are presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5304-5322
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• 2018

Since designing a feedback topology is a practical way to implement interference alignment at reduced cost of channel state information (CSI) feedback, six feedback topologies have been presented in prior works for a K-user multiple-input multiple-output interference channel. To fully reveal the potential benefits of the feedback topology in terms of the saving of CSI overhead, we propose a new feedback topology in this paper. By efficiently performing dimensionality-decreasing at the transmitter side and aligning interference signals at a subset of receivers, we show that the proposed feedback topology obtains substantial reduction of feedback cost over the existing six feedback designs under the same antenna configuration.

• Journal of Communications and Networks
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• 제12권5호
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• pp.492-498
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• 2010

In this paper, a new distributed space-time coded (DS-TCed) non-orthogonal decode-and-forward (NDF) protocol with source antenna switching (SAS) is proposed, where two antennas associated with each radio frequency chain can be alternatively used in the first and second phases. Several DSTC schemes for the NDF with SAS (NDF-SAS) protocol are proposed and their average pairwise error probability for the error-free source-relay (SR) channel is also derived. The simulation results show that the NDF-SAS protocol achieves larger diversity order than the NDF protocol under the error-free and erroneous SR channels.

• 한국멀티미디어학회논문지
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• 제16권9호
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• pp.1067-1076
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• 2013

Known as an important criterion that evaluates performance of future high-speed backbone networks, burst data loss ratio is well-studied in Optical Burst Switching networks. Current literatures mostly focus on reduce burst loss ratio without considering the system stability and link utilization after reducing. In this paper, we propose a novel framework which comes from feedback theoretic to dynamically control burst loss ratio in OBS. The proposed scheme tries to track the pre-set values of burst loss ratio and increases the stability and link utilization degree. The simulation results show that measured burst loss ratio always tracks setup reference with small errors, wavelength channel utilization is increased up to 2% and the system stability is also improved.

• ETRI Journal
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• 제37권4호
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• pp.647-656
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• 2015

This paper proposes a single-RF MIMO receiver that adopts a beam-switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single-RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub-band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.

• 대한전기학회논문지
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• 제40권12호
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• pp.1290-1295
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• 1991

The paper presents the measurement results on the parameters affecting the breakdown mechanism of a large air spacing under switching impulse voltages. Measured parameters are the velocities of leader channels, predischarge currents, electric charges injected into the rod-plane air gap and electric field intensities on the plane. For the 3m air gap under switching impulse voltages, the velocities of leader channel have been measured to be of 1cm/x10S0-6Ts - 5cm/x10S0-6Ts, electric field intensity of 2kv/cm, predischarge current of 1.2-1.6A, the charges injected into the air gap of 11-40x10S0-6TC for 400-887kV impulse voltages.

• 한국지능시스템학회논문지
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• 제22권5호
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• pp.577-582
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• 2012

이동통신망에서는 이동국에서 채널할당 요청이 있을 때 교환국에서 각 기지국에 속한 이동국에 채널을 할당한다. 채널을 할당하는 방식에는 고정채널할당방식과 동적채널할당방식이 있으며 이를 조합한 하이브리드방식이 주류를 이룬다. 주파수를 잘 할당한다는 것은 그만큼 자원을 효율적으로 사용하고 고객에게 양질의 서비스를 제공하는 길이기도 하다. 본 논문에서는 채널을 할당할 때 채널간 간섭을 최소로 하고 채널을 할당하기까지의 시간과 횟수를 최소화하는 방안을 적용한 방식을 제안한다. 이를 구현하기 위해 유전 알고리즘의 프로세서 단계인 검증단계를 통하여 재생산 단계를 거치므로 제안 방식의 정확성과 효율성을 나타낸다. 또한 시뮬레이션을 통해 다른 방식과 비교 검토하여 제안 방식의 효율성을 검증한다.