• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.744-748
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• 2003

Developing an interactive satellite multi­media system, such as a digital video broadcasting (DVB) return channel via satellite (RCS) system, is gaining popularity over the world To accommodate the increasing traffic demand we are motivated to investigate an alternative for improving return channel utilization We develop an efficient method for optimal packet scheduling in an interactive satellite multimedia system using hybrid CDMA/TDMA channels. We formulate the timeslot-code assignment problem as a binary integer programming (BIP) problem, where the throughput maximization is the objective, and decompose this BIP problem into two sub-problems for the purpose of solution efficiency. With this decomposition, we promote the computational efficiency in finding the optimal solution of the original BIP problem Since 2001, ETRI has been involved in a development project where we have successfully completed an initial system integration test on broadband mobile Internet access via Ku-band channels using the proposed resource allocation algorithm.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.129-133
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• 2012

Coordinated multi-point transmission (CoMP) is a candidate technique for next generation cellular communications systems. One of the primary elements discussed in LTE-Advanced technology is CoMP, which can improve cell edge user data rate as well as spectral efficiency due to multiple input multiple output - orthogonal frequency division multiplex (MIMO-OFDM). We consider a system with multiple cells in which base stations coordinate with each other by sharing user channel state information (CSI), which mitigates inter cell interference (ICI), especially for users located at the cell edge. We introduce a new user scheduling method of ICI cancellation and the loss reduction of effective channel gain during the beamforming process, the proposed method improves the system sum rate, when compared to the conventional method by an average of 0.55bps/Hz in different number of total users per cell. It also outperforms the conventional method by approximately 0.38bps/Hz using different SNRs.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.1
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• pp.85-93
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• 2011

2010 trend of Web services is Social Network Service. What does Social Network Service are like this? What could really be used? I also take advantage of future can I do? To elicit answers to the question of Social Network Service and the overall status of the root is used in the case Learn about the current utilization plan after the proposed research. The use of practices being applied to Social Network Service, the three theories were derived positive and negative aspects. Research based on more than the utilization of Social Network Service to build a social safety net to take advantage and use of learning aids were divided into suggestions. Utilized for building a social safety net, and when the reported channel to channel, the use of learning aids to learning that one day, one-on learning by applying the proposed total of four kinds of utilization.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.121-127
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• 2012

In this paper, we propose a new beamforming method which is used in Multiple User-Multiple Input Multiple Output (MU-MIMO) system. An experimental system consists of LTE based TDD base-station which has 2 MIMO elements each of which contains 10-array antennas and 2 mobile terminals each of which has a single antenna. We demonstrate that the Multiple Access Interference can further be reduced by appending a beamforming procedure in MU-MIMO system in which various users share a given channel resource. The proposed algorithm is the ordinary Lagrange beamforming algorithm combined with Zero-Forcing. It is demonstrated that the proposed beamforming method outperforms a conventional method which is the ZF at least by 8dB in terms of SNR through computer simulations. From experimental tests, we verify the feasibility of the proposed beamforming algorithm for realizing a practical LTE based TDD base-station for utilizing channel resources more efficiently.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.3
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• pp.77-85
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• 2018

Multi-User Multiple-Input Multiple-Output (MU-MIMO) is the core technology for improving the channel capacity compared to Single-User MIMO (SU-MIMO) by using multiuser gain and spatial diversity. Key problem for the MU-MIMO is the user selection which is the grouping the users optimally. To solve this problem, we adopt Extreme Value Theory (EVT) at the beginning of the proposed algorithm, which defines a primary user set instead of a single user that has maximum channel power according to a predetermined threshold. Each user in the primary set is then paired with all of the users in the system to define user groups. By comparing these user groups, the group that produces a maximum sum rate can be determined. Through computer simulations, we have found that the proposed method outperforms the conventional technique yielding a sum rate that is 0.81 bps/Hz higher when the transmit signal to noise ratio (SNR) is 30 dB and the total number of users is 100.

• Proceedings of the Safety Management and Science Conference
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• 2010.04a
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• pp.371-392
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• 2010

Since the 21st century, to the worldwide computer, broadcasting, communications and other technologies have be developed. because of the Internet allows real-time information delivery, Information Society that was done quickly. In this study, using information technology, Active measures to enable e-commerce in agriculture is discussed. agricultural e-commerce to the consumer satisfaction surveys were conducted, too. In addition to, as a e-commerce features, informance, convenience, interface presented. After research results, I think information, convenience, interface is important to consumers. Consumers will be spent on activities having a new value. To respond to these consumers, Companies must evaluate the internal capabilities. and outside the assessment continuously. E-commerce will give an effective way to companies. And e-commerce will develop further in the future. Therefore, e-commerce will be done by the long-term plan.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.111-118
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• 2013

This paper presents implementation of Air protocol analyzer and physical layer design algorithm. The analyzer is a measurement system providing real-time analysis of wireless signals between User Equipment (UE) and Node-B. The implemented system proposed in this paper consists of Digital Signal Processors (DSPs) and Field Programmable Gate Arrays (FPGAs). The waveform of Wideband Code Division Multiple Access (WCDMA) has been selected for verification of the proposed system. We designed the analyzer using equalizer algorithm and rake-receiver algorithm. Among various algorithms of designing the equalizer, we have chosen Linear Minimum Mean Square Error (LMMSE) equalizer that uses the inverse of channel matrix. Since the LMMSE equalizer uses the inverse channel matrix, it suffers from a large amount of computational load, while it outperforms most conventional equalizers. In this paper, we introduce an efficient procedure of reducing the computational load required by LMMSE equalizer-based receiver.

• Proceedings of the Safety Management and Science Conference
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• 2008.04a
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• pp.361-366
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• 2008

본 연구는 최근 산업 전반에 걸쳐 도입이 확산되고 있는 RFID(Radio Frequency IDentification)기술과 다채널 음성 전달 서비스 기술을 활용하여, 유비쿼터스 환경에서의 SP(Sales Promotion) 광고를 효과적으로 전달하기 위한 새로운 SP광고용 RFID기반의 다채널 음성 안내시스템을 개발함으로서, 향후 RFID/USN시장을 선점할 수 있는 고부가가치의 신규 미디어 서비스 모델을 제안하고자 한다.

• Journal of the Korean Operations Research and Management Science Society
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• v.24 no.1
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• pp.49-58
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• 1999

A new channel access function is proposed to enhance the performance of the Joint CDMA/PRMA. It is obtained in consideration of the number of terminals in reservation mode and the number of terminals in contention mode whose probability distribution is estimated by applying pseudo Bayesian approach. Simulation results show that the performance of the Joint CDMA/PRMA can be improved by applying new channel access function under voice-only traffic and mixed voice/random-data traffic.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.429-430
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• 2006

In this paper, we describe the architecture of interactive data broadcasting server that can transmit the various data-service contents of the Terrestrial DMB(digital multimedia broadcasting). In the broadcasting environment of the Terrestrial DMB, we enjoys the PADS(program associated data service), or the PIDS(program independent data service) to be executed on various T-DMB terminals as well as the basic video or audio services. This server provides the function such as the data contests management, data channel management, service information configure, return channel connection. Etc. Particularly, this system provides the method to create and transfer the application signaling information for the T- DMB middle application based the java language.