• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1137-1138
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• 2013

최근 드라마에 나오는 패션이나 화장품이 하나의 트렌드가 되고 있고, 드라마가 한류의 또 다른 부분으로 성장하고 있다. 또한 종편채널 도입과 많은 케이블채널 생성으로 전보다 많은 드라마가 등장하고 있으며 드라마 다시보기 기능을 통해 보지 못했던 드라마를 다시 볼 수 있는 기회가 늘어남으로써 이미 종영된 드라마들을 언제든지 다시 볼 수 있게 되었다. 본 논문은 방영되었던 드라마를 보고 싶으나 많은 드라마 중 어떤 드라마를 선택해야 할지 모르는 사용자들에게 사용자에게 가장 잘 맞는 드라마를 추천해주는 추천 시스템을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1234-1236
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• 2023

광대역(Wideband) 통신은 신호 대역폭이 채널의 상관 대역폭(Coherence Bandwidth)를 크게 초과하는 시스템을 나타낸다. 이때, 큰 대역폭을 갖을수록 반송 주파수대역과 사용대역의 최대 및 최소 주파수 간 차이가 커지며, 통신 시스템이 겪는 채널의 주파수 선택적 페이딩 또한 커지게 된다. 수중에서 광대역 통신을 성능을 확인하기 위한 실험을 수행하였다. 실험환경으로는 송·수신기 간 수평 이격거리는 약 10m, 수직 이격거리는 약 190m로 설정하였다. 광대역 신호의 성능을 확인하기 위하여 14kHz와 30kHz의 주파수 대역과 협대역신호와의 비교를 위해 16kHz와 4kHz 대역폭 등 파라메타를 달리하여 설정하였다. x축을 Repetition Freq.와 Repetition Time의 조합으로 설정하였으며, y축을 BER(Bit Error Rate)로 성능결과를 나타내었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.69-74
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• 2003

In this paper, we propose the synchronization recovery algorithm which is suitable to wireless Multimedia of wireless channel situation which is being used OFDM signaling method. The basic of the suggested clock synchronization. restoration Algorithm is to getting the shock response of channel or getting the multipath strength profile through IFTT after the getting the frequency, response of deducted channel from channel deducted of receiver and to trace the location in the channel energy concentrated area of timing area. And it also analysis the start point of 64-QAM and 16-QAM if the sampling clock offset has the sample of ${\pm}$ 1-3, and we identified the occurance of performance deterioration when occures more than 2 samples of offset to compare with star point and BER performance in optimum sampling point result of BER performance checking, and we know that the recovery algorithm proposed algorithm also provide excellent synchronization characteries under frequency, selecting fading channel as result of simulation.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.701-708
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• 2005

The mobility prediction algorithm and the channel reservation scheme have been reported as an effective means to provide QoS guarantees and the efficient resource reservation in wireless networks. Among these prediction algorithms, the recently proposed Detailed-ZMHB algorithm makes use of the history of the user's positions within the current cell to predict the next cell, which provides the better prediction accuracy than the others. The handoff prioritizing schemes are proposed to provide improved performance at the expense of an increase in the blocking probability of new calls. In the soft handoff of the CDMA systems, a mobile can communicate via two adjacent cells simultaneously for a while before the actual handoff takes place. In this paper, we propose a new channel reservation scheme making use of the user mobility pattern information in order to reduce the call dropping probability. Our results show that the proposed scheme gives about 67.5-71.1$\%$ lower call dropping probability, compared to the existing scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2387-2394
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• 2016

It is important to select the most appropriate channel for efficient transmission of massive data in wireless sensor network. In the fixed channel method for wireless sensor node, shortage of frequency may be a major constraint to support a variety of environments. In this paper, the method that seeks common channels between two nodes without common control channels in the existing wireless cognitive radio network is introduced in order to use efficiently the channel of wireless sensor network. The problem of existing method shows the severe degradation of performance that is caused by interference of linkage between selected channels, so that the sequential algorithm is suggested to improve the performance. From the results of computer simulation, the suggested method shows that the link can be set 50% faster than the other methods as the number of links increases because the beacon packet waiting time caused by the interference decreases remarkably.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.138-141
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• 2003

본 논문에서는 STTD(space Time Transmit diversify)를 적용한 적응변조 시스템의 성능을 분석하였다. 무선채널 환경에서는 지연파에 의한 ISI(Intersymbol interference)간섭으로 인해 전송 오율을 증가시키게 된다. 따라서, ISI간섭의 영향을 줄이기 위해 STTD를 적용함으로써 적응변조시스템의 성능개선 정도를 분석하였다. 결과에 의하면, STTD를 적용함에 따라 더 낮은 SNR에서도 변조 다치수가 높은 변조 모드를 선택함으로써 고속ㆍ고품질의 데이터 전송이 가능함을 알 수 있었다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.265-268
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• 2006

본 논문에서는 레티넥스(Retinex) 이론을 이용한 영상개선 알고리즘을 분석하고, 이를 최적화하기 위한 알고리즘을 제안하였다. 기존의 알고리즘이 가진 큰 단점인 수행속도를 보완하기 위해 그리고 작아진 필터 크기 때문에 충분한 면적의 조명정보를 분석하지 못하는 단점을 보완하기 위해 우리의 알고리즘에는 주변함수의 필터크기를 원래의 알고리즘과 비교하여 보다 작은 크기로 조절함으로써, 연산속도를 대폭 감소시킬 수 있었고 4번째 채널로 흑백영상을 선택하므로 써 충분한 면적의 조명정보를 분석하지 못하는 단점을 보완하였다.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.1-5
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• 2015

Recently, RF energy harvesting technology is a promising technology for small-size IoT(Internet of Things) devices such as sensor to resolve battery scarcity problem. When applied to existing cognitive radio networks, this technology can be expected to increase network throughput through the increase of cognitive user's operating time. This paper proposes a optimal channel-selection policy for RF energy harvesting CR networks model where cognitive users in harvesting zone harvest ambient RF energy from transmission by nearby active primary users and the others in non-harvesting zone choose the channel and communicate with their receiver. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.733-738
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• 2013

In this paper, we consider a physical layer security of an amplify-and-forward (AF) transmission in a presence of an eavesdropper in a wiretap channel. The proposed wiretap channel consists of a source, a destination, a relay, and an eavesdropper. Specifically, we consider that the relay has multiple antennas to exploit a diversity gain and a receive/transmit antenna selection schemes are applied to maximize a signal-to-noise ratio. In a practical point of view, we focus on the practical scenario where the relay does not have any channel state information of the eavesdropper while performing an AF protocol at the relay. For a secrecy performance analysis, we analyze a secrecy outage probability of the proposed system in one-integral form and verify our analysis with the computer-based simulation.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.107-113
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• 2013

Mobile mobility and data reliability should be guaranteed as well as amounts of data services are essential in the era of smart media. In order to improve the reliability of high-speed data, strong channel coding and modulation techniques are required. In this paper, the structure of Turbo TCM decoder, applying high-order modulation techniques and the DPSAM method which improves performances in time-selective fading channels in the case of burst errors are suggested through the optimal decoding method and iteration decoding so as to improve bandwidth efficiency in Turbo Codes with excellent encoding gain. The proposed method in comparison with the existing method is that 3dB is superior in case that BER is $10^{-2}$ and the number of iterations is 3. In addition, the function is improved at approximately 6dB in case that BER is $10^{-3}$ and the number of iterations is 7. The proposed method requires additional bandwidth; however, the bandwidth loss can be overcome through Turbo TCM technology on the additional bit rate from the bandwidth loss.