• Korean journal of communication and information
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• v.34
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• pp.306-340
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• 2006

Mobile communications is argued to reshape and activate the existing space by increasing 'mobile communicability en route' and 'real time interaction.' This study is designed to make an empirical analysis on how different the use of a cellular phone is in each different space. In this study, the space is divided into three distinct parts including the private, social and public space. First, spatial micro-coordination and experience of polysemy of place are widely observed in the use of a mobile phone in the private space. Secondly, it is found that a mobile phone contributes to extending the scope of social contacts which in turn compliments the existing social relationship. Moreover, a full-time intimate community that is connected via a mobile phone results in reshaping the social space. Lastly, the study shows that the usage pattern of a mobile phone varies depending on the type of public space. The technological development is envisaged to lead to more demand for the public space while facilitating the use of the public space.

• The Korean Journal of Air & Space Law and Policy
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• v.20 no.2
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• pp.293-306
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• 2005

In order to bridge the digital divide issues in the Asia Pacific region, Japan initiated the Asia Broadband Program, during implementing E-Japan and U-Japan Plans with collaboration among Asia Pacific Counties. This paper describes first joint experiments that were undertaken in Japan, Singapore and China. Then this paper also describes Japanese efforts to build space infrastructure for development of ICT Society in the Asia Pacific region for further international cooperation to bridge the digital divide Article 1, para. 1, of the Outer Space Treaty of 1967, calls for exploration and use of outer space to be carried out for the benefit and in the interests of all countries irrespective of their degree of economic or scientific development. The augmentation of common benefit from space communication could contribute to bridge the digital divide issues in developing countries in Asia Pacific region. Accordingly, space- infrastructure building would be very important to implement common benefit among countries concerned through international cooperation and collaboration

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.14-23
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• 2023

The cooperative communication systems using MIMO(multiple input multiple-output) relay are known as one of the most promising techniques to improve the performance and coverage of wireless communication systems. In this paper, we propose the cooperative communication systems using the relay with multi-antennas and DSTC(distributed space time coding) for decode-and-forward protocol. As using DSTC for DF(decode-and-forward), we can minimize the risk of error propagation at the wireless system using relay system. Also, the MIMO channel cab be formed by multi-antenna and DSTC at the MS(mobile station)-RS(relay station) and at the RS-BS(base station).Therefore, obtaining truly constructive the MIMO diversity and cooperative diversity gain from the proposed approach, the performance of system can be more improved than one of conventional system (relay with single antenna, no relay). The improvement in bit error rate is investigated through numerical analysis of the cooperative communication system with the proposed approach.

• Korean journal of communication and information
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• v.23
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• pp.189-221
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• 2003

This study compares the influence of perceived public opinion on Internet users' willingness to expression in real space with in cyber space. In real space, people who perceive their opinions as minority opinion are reluctant to express theirs publicly because of fear of isolation. But cyber space is the anonymous world. So we can expect that people express their opinions freely without the fear of isolation in this space. This study's results provide the support for our expectation. In cyber space, the minority perception group has as the high willingness to expression of their opinion about the abrogation of the Korean Family Rights Raw as the majority perception group. Both of in cyber space and in real space, it is the perception failure group that makes discrepancy in the willingness to expression. This group has the lowest willingness to expression in both space. However, the other predictors of willingness to expression in cyber space are similar to those in real space. Issue salience, Communication apprehension, and Age are the very significant predictors of willingness to expression in both spaces. Sex and ideology are significant predictors in real space, while the frequency of online conversation is the significant predictor in cyber space.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.136-140
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• 2006

In this paper, we consider the detection of orthogonal space-time block codes (OSTBCs) without channel state information (CSI) at the receiver. Based on the conventional blind cyclic decoder, we propose an enhanced blind cyclic decoder which has higher system performance than the conventional one. Furthermore, the proposed decoder offers low complexity since it does not require the computation of singular value decomposition.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.163-165
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• 2006

This paper presents a implementation of speed sensorless vector control algorithm of induction motor using MATLAB/SIMULINK amd dSPACE DSl104 R&D board. The estimation of rotor flux linkage and rotor speed is carried out using model reference adaptive system(MRAS) method. Estimated rotor speed is used to speed controller of induction motor. Simulation results are presented to confirm speed sensorless vector control algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1042-1050
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• 2014

The performance of underwater acoustic(UWA) communication system is sensitive to the Inter-Symbol Interference(ISI) due to delay spread develop of multipath signal propagation. And due to limited frequency using acoustic wave, UWA is a low transmission rate. Thus, it is necessary technique of Space-time code, equalizer and channel code to improve transmission speed and eliminate ISI. In this paper, UWA communication system were analyzed by simulation using these techniques. In the result of simulation, the proposed Turbo Equalization method based on layered Space Time Codes has improved performance compared to conventional UWA communication.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.8-12
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• 2008

In this paper, we proposes a D-STTD(Double-Space Time Transmit Diversity) communication system with AMC scheme and analyzes its performance using simulation experiments. The AMC scheme selects an optimal channel coding rate and modulation scheme based on the channel response data for signal transmission, creating a balance between error rate and throughput to improve the overall system throughput and transmission quality. The D-STTD scheme complements the conventional STTD(Space Time Transmit Diversity) scheme, yielding about twice the throughput. The simulation results show that the probability of selecting a high MCS(Modulation and Coding Scheme) level increased as the SNR(Signal to Noise Ratio) improved. Furthermore, the D-STTD communication system with AMC scheme provided a more uniform throughput distribution throughout the entire SNR range compared to its counterpart which did not apply AMC scheme. Also, the maximum throughput of the D-STTD communication system with AMC scheme was twice that of a conventional AMC communication system or a STTD communication system with AMC scheme.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1095-1100
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• 2009

The interests and studies on co-creation activity in metaverse space, or MMO communication applications, increase sharply. The study performed the experiments on the participatory virtual space design that has dedicated to the common goal of creativity, and provides the environments to enhance ideas, technologies, and artistic artifacts sharing and communication. The participants were recruited from a community of artists and musicians. They have been actively participated the design process as photographers, painters, media artists, sound artists, and collectors. During the period, we have preceded 5 consecutive experiments, which were led by 5 independent artists, tested the value of co-creation spaces.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.855-860
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• 2016

This study describes the design and implementation of digital Payload power supply. We materialized the interface of the PLDIU and power supply of a satellite bus, and minimized the potential for the occurrence of such erroneous operation circuit ESD through the WCA of the space environment. We designed a reliable power supply through simulation for a TID according to the vibration generated during the launch and space radiation environment, and found no problem in the function and performance through the test space environment after production.