• 항공우주정책ㆍ법학회지
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• 제6권
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• pp.285-291
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• 1994

• Current Optics and Photonics
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• 제2권6호
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• pp.612-622
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• 2018

In wave-front-sensor-less adaptive optics (WFS-less AO) systems, the Jacopo Antonello (JA) method belongs to the model-based class and requires few iterations to achieve acceptable distortion correction. However, this method needs a lot of measurements, especially when it deals with moderate or severe aberration, which is undesired in free-space optical communication (FSOC). On the contrary, the stochastic parallel gradient descent (SPGD) algorithm only requires three time measurements in each iteration, and is widely applied in WFS-less AO systems, even though plenty of iterations are necessary. For better and faster compensation, we propose a WFS-less hybrid approach, borrowing from the JA method to compensate for low-order wave front and from the SPGD algorithm to compensate for residual low-order wave front and high-order wave front. The correction results for this proposed method are provided by simulations to show its superior performance, through comparison of both the Strehl ratio and the convergence speed of the WFS-less hybrid approach to those of the JA method and SPGD algorithm.

• 교육녹색환경연구
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• 제15권3호
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• pp.15-25
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• 2016

본 연구는 학교 내 커뮤니티 형성과정과 그 특성을 밝혀 미래 학교공간이 지향해야할 친사회적 지속가능 환경 구축 및 공간 구성에 필요한 기초자료를 제시하기 위한 것으로 학생들의 휴게 시간을 보다 실증적으로 조사하여 휴게 시간에 대한 새로운 인식과 더불어 학교 내 학생들의 커뮤니티 형성 공간에 대한 이해를 돕고자 수행되었다. 이에 학교 내 휴게시간 커뮤니티 형성과정과 그 특성을 밝히기 위하여 연구자가 근무하는 지역의 가장 최근 개교한 미래형 고등학교를 대상으로 연구를 진행하였다. 학교 내 커뮤니티 공간 조성에 대한 분석 결과 학교 내 사회적 소통 및 상호작용 촉진을 위한 커뮤니티 공간에 대해서 성별, 학년별 차이 없이 모두 필요하다는 의견이 많았고, 커뮤니티 공간으로 가장 적합하다고 생각되는 공간으로는 홀 알코브 공간, 복도 알코브 공간, 교실인접 소규모 공간, 다목적 계단 등으로 나타났다. 또한 학생들이 가장 원하는 커뮤니티 공간으로는 홀, 복도 알코브 공간으로 각각 만남, 소통, 휴식, 사회적 교류 등 소통 활동을 가장 하고 싶어 하였다.

• 한국언론정보학보
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• 제16권
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• pp.207-254
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• 2001

This study is focused on forecasting the future of tole-democracy. Many Scholars expect that internet provides technological space needing realizing the tole-democracy or deliberate democracy. Especially in Korea, this expectation is higher than other nations because of political corruption and inefficiency. Therefore internet is intended to considering as new technologies reforming political process. In 16th the general election period, many candidates established home page and used as election campaign tool. And a little of home pages is payed attention to among voters. In spite of using internet as political medium, many political communication researchers have a doubt that internet will realize ideal direct democracy. It's reason is that internet is open and anonymous space. At anonymous space, communication participators is tended to be irresponsible and non-serious. Therefore it is hard that cyber-politics will be ideal type of democracy. In this context, this paper analyzed how pauicipators communicate with others at cyber bulletin board establishing candidate's home pages. Main research questions is how do discussions at cyberspace fulfill the conditions of deliberate democracy. Therefore, concrete questions include; who are participators at candidate's cyber bulletin board; which pattern do they communicate; what is the theme of communication; which effects do the anonymous character of cyberspace influence. To that purpose, this study conducted content analysis on 4,210 written matters at 82 cyber bulletin boards of candidate's home page establishing during 16th the general election period. It can be found that cyberspace in Korea still is not deliberate democracy space and not will be. Firstly, discussion patterns at cyber bulletin board is "candidate with supporters communication space. To be exact, it is said that candidate's home page is "the space of self-convincing among supporters." Secondly, the main themes of discussion are simple emotional expressions; "I support you!" "fighting" "Be vigor" etc. By contrast, real political contents'-central or local political matters - is relatively few. In the mode of expression, real political messages are more positive, logical than simple expressions, candidates private matters. Especially this characteristic will make cyberspace as "mutual slander space" consolidating anonymous characteristic of cyberspace. finally, Cyberspace in Korea still is not real "public sphere" realizing deliberate process. Therefore to be real public sphere, it is needed to participant's ethical maturity and political citizenship. In conclusion, it is difficult that cyberspace will reconstruct the Athene's Agora. On the contrary, Cyberagora will like to be irrespectable area fulfilling the sweeping. Making the deliberate space, technological possibility and ethical condition will have to be balanced together.

• 한국언론정보학보
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• 제37권
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• pp.342-376
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• 2007

이 연구는 온라인 롤프레잉 게임 이용자가 현실공간과 가상공간에서 형성하는 자아정체감의 관계를 탐색하고, 그것이 온라인 게임중독과 현실부적응감에 미치는 영향을 경험적으로 검증하고자 했다. 분석결과 현실공간의 자아정체감과 가상공간의 자아정체감은 정적으로 높은 상관성을 보였다. 구체적으로 현실공간의 자아정체감이 높은 사람들은 가상공간에서도 높은 자아정체감을 보였다. 또한 두 공간의 자아정체감은 게임중독과 현실부적응감과도 매우 높은 상관성을 보였는데, 두 공간 모두 자아정체감이 높을수록 게임중독과 현실부적응감 수준은 낮아지는 것으로 나타났다. 그중에서도 현실공간의 자아정체감은 게임의 부정적 효과들, 즉 중독과 현실부적응감 수준을 결정하는 요인으로 나타났다. 가상공간의 자아정체감은 비록 독립적인 영향력을 발휘하지는 못했지만, 현실공간의 그것과 상호보완적으로 영향을 미칠 가능성을 보였다. 이것은 현실공간에서 자아정체감이 낮은 사람들에게 가상공간이 이상적인 자아를 발견하고 자신에 대해 긍정적인 인식을 발전시킬 수 있는 대안적인 공간으로 작용하지 못함을 의미한다. 중독에 이르고 현실부적응감 수준이 높은 사람들은 현실공간과 마찬가지로 가상공간에서의 자신에 대해서도 부정적으로 인식하기 때문이다.

• International Journal of Internet, Broadcasting and Communication
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• 제12권1호
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• pp.116-121
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• 2020

With the recent development of the 4th Industrial Revolution, efforts have been made to carry out communication in a smart factory, farm, etc. at low cost and reliably. Methods for utilizing empty frequencies using TVWS(TV White Space) have been studied which can be used locally within 30 km. However, there have not been many studies on Path-Loss model considering Korean environment. In this paper, the Path-Loss model is divided into LOS (Line Of Sight) and NLOS (None LOS). In case of LOS model, we checked the difference between Free space model, Friis model, 2-ray model and Hata model with measured data. In the case of NLOS model, we checked the difference between Lee Model, ITU-R526-3 Model with measured data. In order to overcome the difference in Korean environment, we derived a model that can be applied in LOS and NLOS and prove its usefulness through performance evaluation through simulation.

• 한국시뮬레이션학회논문지
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• 제13권2호
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• pp.1-12
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• 2004

This paper estimated the arrival angle and electric wave delay time using the space method law and the directions of arrival (DOA) estimation algorithm in case of signal correlation. Space method law is the method used to repress cross correlation before applying the weight value to the receiving signal. The values of the diagonal elements in the correlation matrix were averaged to replace as the diagonal elements value. In the area of wireless communication or mobile communication, there are high correlations in case of low delay time difference in multiple waves. This causes the quality of the communication to drop due to interference with the desired signal elements. This paper estimated the arrival angle and electric wave delay time using the space method law and the MUSIC algorithm. With the arrival angle algorithm, the arrival angle cannot be estimated below 5 in case of signal correlations because the angle resolution capacity decreases accordingly. The super resolution capacity was estimated to determine the arrival angle below 5 in this paper. In addition, the proposed algorithm estimated the short delay time difference to be below 20ns.

• International Journal of Computer Science & Network Security
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• 제21권12호
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• pp.323-327
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• 2021

The article examines the process of professional training in educational institutions, media technologies and methods of media communication in the educational space of the institution, characterizes the place of media technologies in the educational space in the context of the term "educational space" itself, systematizes the methods of media communications in education. The peculiarities of media education as a set of means and methods of teaching young people adequate media perception are pointed out.

• Journal of information and communication convergence engineering
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• 제6권3호
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• pp.353-357
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• 2008

One objective in developing the next generation of wireless communication systems is to increase data rates and reliability. A promising way to achieve this is to combine multiple-input and multiple-output signal processing with a space-time coding scheme, which offers higher coding and diversity gains and improves the spectrum efficiency and reliability of a wireless communication system. It is noted, however, that time delay differences and phase differences among different channels increase symbol interference and degrade system performance. In this letter, we investigate phase differences and their effects on multiple-input and multiple-output systems, and propose a compensation algorithm for the Rayleigh fading model to minimize their effects.

• International Journal of Aeronautical and Space Sciences
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• 제5권1호
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• pp.6-18
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• 2004

This paper addresses the development and design of the HAUSAT-l (Hankuk Aviation University SA'Tellite-D communication subsystem, which is a next generation picosatellite, developed by SSRL (Space System Research Lab.) of Hankuk Aviation University. The communication subsystem generally consumes the majority of power and volume for picosatellites, and thus its design is critical to the overall satellite and mission plans. The HAUSAT-l designs are implemented by using the 145.84 MHz for uplink and 435.84 MHz for downlink frequency bands. The simulation and test results of the homemade radio and the TNC (Terminal Node Controller) integrated on the HAUSAT - I , a picosatellite scheduled to launch on September 2004 by Russian launch vehicle "Dnepr", are presented for EM, QM and FM, respectively.