• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.57-58
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• 2006

Ad hoc MAC protocols using directional antennas can be used to improve the network capacity by improving spatial reuse. But, the directional MAC protocols have the problem of deafness and have a poor throughput performance. The dual-channel DMAC protocol has been proposed to mitigate deafness and improve spatial reuse. In this paper, we propose a dual-channel DMAC protocol using the omnidirectional antenna for an out-of-band tone and directional antennas for control/data channels. In the proposed MAC protocol, an omnidirectional out-of-band tone mitigates deafness and directional antennas used in control/data channels improve spatial reuse and reduce interference packets. The throughput performance of the proposed MAC protocol is confirmed by computer simulations using Qualnet ver. 3.8 simulator.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.251-258
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• 2013

A procedure for antenna parameter selections is proposed that considers the relationships between synthetic aperture radar performance and the antenna parameters of a parabola-type reflector antenna with a central flat dish. The effects of a central dish designed for weight reduction on the antenna beam pattern are also quantitatively analyzed using commercially available software based on the physical optics algorithm. The results of the theoretical analysis and simulation predict that a larger size of the central dish results in an increase in the sidelobe level, which is the reason for the increase in two important ambiguities, such as range ambiguity ratio (RAR) and azimuth ambiguity ratio (AAR). The dependence of RAR and AAR on Pulse repetition frequency is also analyzed and discussed.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.361-364
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• 2003

The customer premise facilities assume an important role in the telecommunication networks. The present technical standards for domestic customer cabling facilities are established with the multimedia environment reflected, but are insufficient for accommodation of multimedia services of the ultra high-speed information and communication networks In the present paper, the status of international standardization as well as technical standards in the U.S.A., Japan, other countries are reviewed and the domestic technical standard and emblem is investigated and analyzed in order to enhance customer cabling facilities in Korea. The problems with emblem are analyzed, and how to improve customer cabling telecommunication facilities is suggested based on the above.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.871-874
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• 2002

The information and communications service is recently being broadened, having much faster transmitting speed and multimedia performance. In addition, its introduction to general residential sites and construction of network facilities are being activated. Therefore new setup paradigm is being established other than the environment of plain old telephone service and data communication. In the present paper, the status of international and domestic standardization are reviewed and the operational environment of customer premise telecommunication facilities are investigated and analyzed. In order to enhance customer cabling facilities in Korea. The problems with the operational environment are analyzed, and how to improve customer cabling telecommunication facilities is suggested based on the above.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.621-624
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• 2016

Demarcation point is technical regulation for preventing conflict and improving the efficiency of the maintenance by discriminating facility area between telecommunication operator and telecommunication user. Since current demarcation point is defined on the basis of the telephone network, it is necessary to examine the applicability to various connection methods for the introduction of new services and facilities. This paper is to discuss for the domestic and international regulations of the demarcation point, and matters to be taken into account.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1099-1102
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• 2009

Conventional stereoscopic (3D) displays using binocular parallax generate unnatural conflicts between convergence and accommodation. Those conflicts can affect the ability to fuse binocular images and may cause visual fatigue. This study examined time-series changes in visual fatigue and depth sensation while viewing stereoscopic images with changing parallax. We examined the physiological changes, including the subjective symptoms of visual fatigue, when viewing five parallax conditions. The time-series results suggest that 2D and 3D images produce significantly different types of visual fatigue over the range of binocular disparity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.642-646
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• 2005

We propose an improved partial response maximum likelihood (PRML) detector with the branch value compensation of Viterbi decoder for asymmetric high-density optical channel. Since the compensation value calculated by a survival path is applied to each branch metric, it reduces the detection errors by the asymmetric channel. The proposed PRML detection scheme improves the detection performance on the $2^{nd},\;3^{rd}\;and\;4^{th}$ order PR targets for asymmetric optical recording channel.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.384-389
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• 2009

Optical wireless communication (OWC) systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. OWC facilitates rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. Nevertheless, the performance of this new technology depends strongly on the atmospheric conditions and the characteristics of the link. In this work, we study the influence of these parameters on both the average (ergodic) capacity and the outage capacity of an OWC system over moderate to strong turbulence channels modeled by gamma-gamma distribution. Moreover, we compare the results that we obtain estimating the average and outage capacities.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2169-2172
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• 2003

네트웍을 이용한 외부의 침입을 탐지하기 위해 침입탐지시스템이 1980년대부터 연구되었다. 침입탐지 시스템은 침입을 발견하면 경보데이터나 로그데이터를 생성하는데 서로 상이한 데이터 집합으로 인해 별도의 데이터 매핑이 필요한 문제점을 해결하고자 IETF 의 침입탐지 관련 그룹인 IDWG 에서 IDMEF를 제안하였다. 본 논문에서는 이러한 IDMEF 형식을 지원하는 경보데이터 구조를 설계하고, 이를 통하여 상위의 보안제어서버에서 상이한 침입탐지 시스템으로부터의 경보데이터를 저장, 관리할 수 있는 방법을 제공한다 이러한 기본적인 경보데이터 관리 이외에 저장된 경보데이터를 통한 공격자 정보 추출, 피해 호스트 정보 추출등의 부가적인 방법 또한 제공한다.

• Journal of Information Processing Systems
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• v.7 no.1
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• pp.17-28
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• 2011

Despite the fact that the deployment of sensor networks and target tracking could both be managed by taking full advantage of Voronoi diagrams, very little few have been made in this regard. In this paper, we designed an optimized barrier coverage and an energy-efficient clustering algorithm for forming Vonoroi-based Wireless Sensor Networks(WSN) in which we proposed a mobile target tracking scheme (CTT&MAV) that takes full advantage of Voronoi-diagram boundary to improve detectability. Simulations verified that CTT&MAV outperforms random walk, random waypoint, random direction and Gauss-Markov in terms of both the average hop distance that the mobile target moved before being detected and lower sensor death rate. Moreover, we demonstrate that our results are robust as realistic sensing models and also validate our observations through extensive simulations.