• The Korean Journal of Air & Space Law and Policy
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• v.6
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• pp.285-291
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• 1994

• Current Optics and Photonics
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• v.2 no.6
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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.

• The Journal of Sustainable Design and Educational Environment Research
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• v.15 no.3
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• pp.15-25
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• 2016

The purpose of this study is to reveal the process of forming a community in the school and to present the basic data necessary for the establishment of a social sustainable environment and space for future school space. In addition to a new awareness of time, it was carried out to help students understand the community forming space in the school. The purpose of this study was to investigate the formation process and characteristics of resting time community in the school. As a result of the analysis on the formation of community space in the school, there were many opinions that community space for social communication and interaction promotion in school is all without difference by gender and grade, and as a space which is considered to be most suitable as community space. A hallway alcove space, a small space adjacent to the classroom, and a multipurpose staircase. In addition, students wanted to make the communication activities such as meeting, communication, relaxation, and social exchange into the hall and corridor space in the corridor as the most desirable community space.

• Korean journal of communication and information
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• v.16
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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.

• Korean journal of communication and information
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• v.37
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• pp.342-376
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• 2007

This study attempted to explore relationship between self-identities in real space and in virtual space and to inspect empirically both self-identities' influence on addiction and society maladaptation of online role playing game users. The verified results through this study are summarized as follows. First, both self-identity in real space and self-identity in virtual space represent strong interrelationship. In detail, the user with strong self-identity in real space shows strong self-identity in virtual space. Second, self-identities in two spaces have the negative interrelationship with game addiction and maladaptation. Whether real space or virtual space, the higher self-identity, the lower the levels of game addiction and maladaptation. Especially, self-identity in real space appeared an influential variable determining the level of addiction and maladaptation. Although self-identity in virtual space have not an independent influence, it has the possibility to effect complementary with self-identity in real space. This fact means that virtual space is not the place where the user with weak self-identity in real space can discovers the ideal self. Because they also experience the negative recognition about oneself in virtual space.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.1
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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.

• Journal of the Korea Society for Simulation
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• v.13 no.2
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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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• v.21 no.12
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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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• v.6 no.3
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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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• v.5 no.1
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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.