• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.4
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• pp.141-152
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• 1984

Nowadaty, To keep pace with the mass transportation carried out by vessels in the international trade, the Korean government is trying to make a rapid progress to be a higher ranked shipping country to the world through the shipping increase. For the effective management of international trade by vessels and the safe operation of vessels, it is indispensable for ships radio communication to be effective and smooth. Therefore, to enhance the efficiency of ships radio communication is one of the primary factors to be solved for the econimics of shipping management. The reserch area is not only limited to the ships radio communication on the North Pacific Ocean but limited to the ships radio communication which is one of the chiefest methods of communications. From the research for the efficient methods of ships radio communication, the following results are obtained. (1) The operator on ships radio communication should have the knowledge of specific know-how and wide experience in the operation of ships radio communications. (2) The operator should abopt the radio propagation prediction made by the Ministry of Communications to use the best ionosphere reflection in the short wave communications. (3) The increase the radio officer of 1 to 2 in order to contrive the safety at sea and to keep the ships radio communication fare low. (4) The owner should pay their attentions to the education and employment of radio officer. (5) The authorities concerned on the ships radio communication should estabilish the effective and consistent policy for the ships radio officers.

• ETRI Journal
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• v.29 no.5
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• pp.569-595
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• 2007

Particularly in wireless communications, link errors severely affect the quality of the services due to the high error probability and the specific error characteristics (burst errors) in the radio access part of the network. In this work, we show that thorough analysis and appropriate modeling of radio-link error behavior are essential to evaluate and optimize higher layer protocols and services. They are also the basis for finding network-aware cross-layer processing algorithms which are capable of exploiting the specific properties of the link error statistics, such as predictability. This document presents the analysis of the radio link errors based on measurements in live Universal Mobile Telecommunication System (UMTS) radio access networks as well as new link error models originating from that analysis. It is shown that the knowledge of the specific link error characteristics leads to significant improvements in the quality of streamed video by applying the proposed novel network- and content-aware cross-layer scheduling algorithms. Although based on live UMTS network experience, many of the conclusions in this work are of general validity and are not limited to UMTS only.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.258-258
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• 2006

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.71-74
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• 2010

본 연구에서는 P3기반의 프로젝트 관리 모델을 제안하였다. 제안한 모델은 최근 프로젝트 추진의 범위가 신제품개발, 연구관리, 시스템개발과 경영혁신을 포함하는 등 다각적으로 전개됨에 따라 다양한 프로젝트를 수용할 수 있도록 Program, Project, 그리고 Portfolio를 통한 이슈, 예산, 자원, 위기, 변경관리, 산출물 관리 등에서 신속한 의사결정을 지원할 수 있도록 구현 하였으며, 이렇게 구현된 제안 모델은 빠르게 변화 되는 프로젝트 관리에서 신속한 의사결정과 프로젝트와 연계된 사람 간의 협업을 지원하는 면에서 우수함을 보인다.

• ETRI Journal
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• v.40 no.1
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• pp.89-100
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• 2018

Millimeter wave communication is one of the main disruptive technologies in upcoming 5G mobile networks. One of the first candidate applications, which will be commercially ready by 2020, is wireless backhaul links or wireless last mile communication. This paper provides an analysis of this use-case from radio engineering and implementation perspectives. Furthermore, preliminary experimental results are shown for a proof-of-concept wireless backhaul solution developed within the EU-KR 5GCHAMPION project, which will be showcased during the 2018 Winter Olympic Games in Korea. In this paper, we verify system level calculations and a theoretical link budget analysis with conductive and radiated over-the-air measurements. The results indicate that the implemented radio solution is able to achieve the target key performance indicator, namely, a 2.5 Gbps data rate on average, over a range of up to 200 m.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.614-618
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• 2012

Smart grid is widely considered to be a next generation power grid, which will be integrated with information feedback communications.However, smart grid communication technologies are subject to inefficient spectrum allocation problems. Cognitive radio networks can solve the problemof spectrumscarcity by opening the under-utilized licensed bands to secondary users. In this paper, adaptive cognitive radio spectrum sensing and sharing algorithms are developed for smart grid environments. Simulation results are presented to demonstrate the effectiveness of the proposed scheme in comparison with other existing schemes.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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• pp.19-24
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• 1983

This study begins with investigation of the purpose and background of the International convention on Standards of Training, Sertification and Watchkeeping for seafarers 1978, London(STCW) which will be put into force on and after 28th April 1984. Author tried to confirm those common points on requirement of the qualifications between the radio officer regulated it. the STCW Convention and radio communications between the radio officer regulated in the STCW convention and radio communication operator's general certificate in the Radio Regulations annexed to the International Telecommunication convention. Then, Japanese communications administration is taken as a model for the comparative analysis, as Japan and Korea have many resembling aspects, especially legal and social aspects. Therefore, as one of urgent tasks of Korean Communications Administration preparing for the STCW convention, Istressed on partial amendment of the Korean Radio Regulatory Act.

• Journal of Communications and Networks
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• v.11 no.2
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• pp.115-121
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• 2009

In cognitive radio (CR) systems, cognitive users can use the frequency bands when the primary users are not present. Hence, reliable detection of available spectrum is foundation of cognitive radio technology. To ensure unimpaired operation of primary users, cooperative spectrum sensing is needed. To reduce the network overhead of cooperative spectrum sensing, a novel cooperative spectrum sensing algorithm based on credibility is proposed. In particular, the close-form expressions for probability of detection and false-alarm are derived for the novel algorithm, and expression for the average overhead used for cooperation is given. The thresholds design method for the algorithm is also discussed. The conclusion is proved by computer simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.290-296
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• 2020

In this paper, we analyze the effect of mobility on the performance of full-duplex radio. For this, we implement a full-duplex radio prototype using a software-defined radio that is powered by a battery and can thus function in mobile environments. In addition, we compare the performance of self-interference cancellation schemes for two cases considering multi-antenna based full duplex radio and circulator based full duplex radio, respectively. Finally, we show a negative effect of mobility on the self-interference cancellation performance of the full-duplex radio system, and analyze the effect of the update period of the self-interference cancellation filter on the performance. In particular, when the update period is reduced by about 1000 times, the power of self-interference is reduced by 5.7dB for circulator-based full-duplex radio and 3.1dB for both antenna-based full-duplex radio.

• Annual Conference on Human and Language Technology
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• 2008.10a
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• pp.177-182
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• 2008

본 논문에서는 질의응답시스템에서 응답 추출 대상 문서로 사용할 적절한 문서를 찾는 방법으로 기계 학습 기반의 문서 품질 평가 기법을 사용한다. 본 논문에서는 기존 연구와 달리 객관적인 정보를 많이 포함하고 있는 문서를 선별하는 목적으로 문서 품질 평가를 위한 유용한 자질들을 제안한다. 본 논문에서 정의한 정보성 자질은 정보의 양을 측정하는 자질과 정보의 객관성을 측정하는 자질로 구성된다. 실험 결과, 기존 문서 품질 평가 연구에서 주로 사용된 자질들만 사용한 경우와 새로운 자질들을 추가한 경우를 비교하였을 때, 1.5배 정도 높은 평균 정확률을 보였다. 제안하는 자질들 중에는 정보성 자질이 매우 유용한 자질이었고, 가독성 자질은 비교적 낮은 성능을 보였다. 문서의 여과 실험 결과, 96.4%의 재현율을 유지하면서 전체 문서 집합 중, 60%에 해당하는 저품질 문서를 여과할 수 있었다.