• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.13-15
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• 2015

본 논문에서는 하나의 중계기가 하나의 송신기로부터 신호를 받아 증폭한 후에 수신기로 재전송하는 방식으로 송신기와 수신기 사이의 통신을 돕는 네트워크를 고려하였다. 중계기가 독자적인 에너지원이 없는 경우 일정한 양을 에너지를 확보하여 중계에 사용하기 위해서 송신기로부터의 신호를 에너지로 하베스팅하는 모델을 생각하였다. 또한, 나아가 현재의 다양한 무선통신 네트워크에서 사용중인 적응변조를 적용하여 항상 일정이상의 비트오율을 만족할 수 있는 더욱 현실적인 모델이 되도록 하였다. 이러한 모델에서 정해진 만큼의 시간을 하베스팅에 사용했을 경우 처리율을 구하였으며, 나아가 그 시간을 최적화하여 유도한 처리율을 최대화하는 문제를 만들었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.54-56
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• 2015

In this paper, we investigate a physical-layer network coding (PNC) in a two-way relay channel (TWRC) where two sources send and receive data with each other by help of a relay node with multiple antennas. We focus on the multiple-access phase of the TWRC in this paper. It is assumed that the source nodes do not know the wireless channel and the wireless channel independently varies in time, that is, fast fading environments. At the relay node, the channel is assumed to be perfectly known. The relay node utilizes the channel sate information and applies maximum likelihood ratio for detecting received signals. Through extensive simulations, it is shown that a bit error rate (BER) performance becomes improved as the number of antennas at the relay node increases.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.82-90
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• 2003

Recently, a new concept of telecommunication system, utilizing stratospheric platforms such as airships or airplanes, has been proposed. This system aims to provide broadband multimedia services, i.e. high-rate multimedia service, high-rate internet service, and leased line service. In this study, operation concept of the system is defined and by allocating required functions on the system and its subsystems, conceptual design of the ground control system for the stratospheric platforms is established and proposed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.244-246
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• 2022

중계 시스템은 드론과 무선 장비들을 사용하기 시작하였고 여러 가지 시스템을 도입하고 있는 추세이다. 따라서 본 논문에서는 드론과 4K, 무선을 기반으로 한 중계 시스템을 제안한다. 제안한 시스템은 드론을 활용하여 더욱 현장감 있고 역동적인 콘텐츠를 제작할 수 있다.

• 전자공학회논문지 IE
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• v.47 no.1
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• pp.34-40
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• 2010

Even if use ICS repeater in radio communication system, distance between Donor antenna and Service antenna though do much isolation degree must that shortcoming have. Proposed IP antenna to supplement this shortcoming in this paper. Result Doner antenna and isolation of Service antenna that measure through examination do 1.5m and when did direction 180 degree, Isolation confirmed that is measured 110dB. Confirmed that can unuse ICS repeater through this result and service by general RF repeater.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.2
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• pp.47-52
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• 2009

최근 통신사업자들이 초고속 무선 인터넷 서비스를 위하여 와이브로 네트워크를 설치하고 있으나, 산간 지역이나 네트워크 인프라를 구축하기 어려운 지역에서는 와이브로 서비스를 제공받지 못하는 경우가 생긴다. 현재 와이브로 네트워크에서는 서비스를 제공받지 못하는 음영지역을 중계기를 이용하여 해소하고 있다. 본 논문에서는 이러한 음영지역에 고정 중계기를 설치하는 대신 고정 중계기 비용 절감 및 능동적인 네트워크 확장이 가능하도록 WLAN 네트워크에서 연구되고 있는 ad-hoc 기반의 멀티홉 릴레이 방식을 사용하여 음영지역 문제를 해결하고자 한다

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.38 no.12
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• pp.12-17
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• 2009

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.25-32
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• 2010

This paper evaluates the outage probability of cognitive relay networks with cooperation between secondary users based on the underlay approach, when multiple primary receivers coexist with secondary users. Using an appropriate relay selection criterion in cognitive radio networks, we derive the outage probability of secondary user. It is shown that the outage probability increases as the number of primary receivers increases and we quantify the increase. Through the simulation results, we verify that the performance of relaying transmission is varied more sensitively compared to that of direct transmission as the number of primary receivers increases. In addition, the relaying transmission can be less efficient than the direct transmission when multiple primary receiver exist but it can be more efficient than the direct transmission by increasing the relay selection diversity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.7-12
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• 2014

The data forwarding transmission is an important function of the relay in cooperative communication in wireless communication systems. However, additional relay cause the waste of power consumption and cost. Therefore, in this paper, we consider how to use the user mobile devices in stead of relays to deal with this problem. In this paper, we proposed the protocol that divide each relay into two states of idle and non-idle. The receiver has two functions of base station and user mobile device. In this case, it is possible that no additional cost, and improve the spectral efficiency and network capacity. We verified BER performance for the proposed protocol over Rayleigh fading through Monte-Carlo simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.281-289
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• 2009

Wireless relay attracts great attention as a core technology of next generation wireless communication systems since it enables reliable communications and extends cell coverage by supporting shadowed users. In this paper, we Propose transmit power and subcarrier allocation scheme for downlink OFDM systems with multiple decode and forward (DF) relays to increase data rate with fixed bit error rate (BER) and sum power constraint. In simulation results, average data rate based on the proposed schemes are evaluated and compared to that of the other schemes. It is also shown that the performance loss of the proposed scheme is negligible compared to the optimal scheme, while its computational complexity is reduced considerably.