• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.111-116
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• 2012

In this paper, we fabricate a WiFi based video transmitting equipment and establish a video transmitting system for realtime transmitting of accident scene on expressways. The transmitting equipment is based on the H.264 video codec and embed WiFi module. The transmitting equipment can transmit video and also meta data such as location positioning through the Wibro network using a Wibro terminal. From test results, it is clear that high density videos were transmitted while the vehicle carried by the video equipment was traveling with velocity of 80 km/h.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.325-333
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• 2010

Most communication systems including Wibro use quasi-cyclic LDPC codes composed of circulants. However, it is very difficult to design quasi-cyclic(QC) LDPC codes with optimal degree distribution satisfying conditions on layered decoding and girth due to the restriction of the size of its base matrix. In this paper, we propose a good solution by introducing superposition matrices to QC LDPC codes. We derive the conditions on checking girth of QC LDPC codes with superposition matrices, and propose new decoder to support layered decoding both for original QC LDPC codes and their modifications with superposition matrices. Simulation results show considerable improvements to convergence speed and error-correcting performance of proposed scheme which adopts QC LDPC codes with superposition matrices.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.235-245
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• 2008

The purpose of this paper is to develop a genetic algorithm to determine the optimal locations of base stations and relay stations in Wibro MMR Network. Various issues related to the genetic algorithm such as solution representation, selection method, crossover operator, mutation operator, and a heuristic method for improving the quality of solutions are presented. The computational results are presented for determining optimal parameters for the genetic algorithm, and show the convergence of the genetic algorithm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.60-66
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• 2011

Currently, ITS (Intelligent Transport System) system is supporting a variety of services to be enhanced traffic's efficiency and driver's safety as developing of information communications and network technology. High data transfer communications such as Wibro, HSPA and WAVE are used for providing ITS services, but there are some differences from specification and performance applied. So, users who are employing the communication systems to transfer data whatever they want to have been suffering from use. In this paper, it is proposed that user can use various high data transfer communication systems wherever environments they are in using adaptation of system change. Also, it is implemented performance of system which uses alternate communication scheme in mobile terminal based on embedded platform.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.841-843
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• 2014

Mobile communication systems such as WCDMA, Wibro, LTE, etc are being developed to meet the explosively increasing demands for wireless data. These communication systems are using the power at all times. In general a base station has all of the communication systems mentioned above in order to provide a more convenient service to a number of users. The demands for wireless data are changed according to time and location. If the mobile communication systems are selectively operated according to the demand for wireless data then the consumed power can be saved. This paper describes the design and implementation of the load management system which controls the supplied power to the mobile communication infrastructures depending on the demand of wireless data.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1112-1114
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• 2005

Core position of the M2M (Machine to Machine) is device integration fusion using an emerging wireless and next internet technologies as well as IEEE 802.x, Bluetooth, Zigbee, DMB, Wibro etc. for ubiquitous environment that is complementary with IT839 strategy from Ministry of Information & Communication. This paper define and deploy about major functional requirements of M2M devices and middleware for how to it works, worldwide M2M technology trend & activities with its current & future application in manufacturing area that is called u-Manufacturing (Ubiquitous Manufacturing).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.18-26
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• 2006

In this paper, we compare the performance of three representative STBC schemes, Alamouti's, Tarokh's and quasi-orthogonal schemes under cellular mobile environments when they are applied to the OFDM system. We first study the encoding algorithms of the STBC schemes along with the development of adequate demodulation algorithms. The OFDM parameters are selected by considering the Wibro system and adequate modulation schemes are assigned for each STBC schemes according to the transmission rate from 2bps/Hz to 4bps/Hz. The STBC-OFDM systems employ Walsh orthogonal codes covered along the frequency domain in order to estimate the channel information for different transmit antennas. We finally compare the performance of the STBC-OFDM systems according to the transmission rate through computer simulations in various mobile channel environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.1-8
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• 2008

Low Density Parity Check codes(LDPC) are recently focused on communication systems due to its good performance. The standard of WiBro has also included LDPC codes as a channel coding. The weak point of implementation for LDPC encoder is that conventional binary Matrix Vector Multiplier has many clock cycles which limit throughput. In this paper, we propose semi-parallel architecture by using cyclic shift registers and exclusive-OR without conventional Matrix Vector Multipliers over the standard parity check matrices with Circulant Permutation Matrices(CPM). Furthermore, multi-rate encoder is designed by using proposed architecture. Our encoder with multi-rate for IEEE 802.16e LDPC has lower clock cycles and higher throughput.

• Management & Information Systems Review
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• v.32 no.3
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• pp.247-261
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• 2013

Recently, the smart phone, a carrying along terminal connection technology such as Galaxytap/iPad etc. evolves, and supply is increasing rapidly, is included for smart phone because various sensor technologies are developed and service application that is acted in terminal with this is accompanied and grow. Continuously 4 generation to 3 Gs, Wibro Wireless network technology of communications a LTE technology from that is constructed, environment for Ubiquitous realization is being constructed fast. Therefore, in this paper it can inquire state of electronic, furniture devices through apartment complex web server and gear that control groove network at smart phone, and control, and confirms home state prevention of crimes state, and video inquiry of position that CCTV is placed in apartment complex was available. And it proposed integrated smart apartment with parking system and medical system using RFID system in ubiquitous environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.557-567
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• 2005

We evaluate the BER performance of OFDMA system for Wibro services in frequency selective Rayleigh fading channel, considering the carrier frequency offset and the nonlinear high power amplifier. In the uplink OFDMA, nonlinear amplifier and frequency offset introduce larger BER degradation than in the downlink. We explain the reason and obtain the required output back-off of the nonlinear amplifier and value of frequency offset for good BER performance.