• Journal of applied mathematics & informatics
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• v.33 no.1_2
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• pp.211-217
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• 2015

A dynamic spectrum access scheme with channel partitioning for secondary handover calls in cognitive radio networks is proposed to reduce forced termination probability due to spectrum handover failure. A continuous-time Markov chain method for evaluating its performance such as blocking probability, forced termination probability, and throughput is presented. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed scheme with channel partitioning.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.763-766
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• 1999

Direct-Sequence code-division multiple access(DS/CDMA) is considered by many to be a promising technology for future wireless communication networks. In this paper, we report new analysis for probability of BPSK CDMA hypothesis test in jointly distributed AWGN Rayleigh-fading received signal. In previous method, analysis is performed on AWGN or Rayleigh-faded signal in separately. In this paper, we propose model for hypothesis test system of the AWGN Rayleigh-faded received signal.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.491-494
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• 1999

Introduction of digital communication network such as Integrated Services Digital Networks(ISDN) and digital storage media have rapidly developed. Due to a large amount of image data, compression is the key techniques in still image and video using digital signal processing for transmitting and storing. Digital image compression provides solutions for various image applications that represent digital image requiring a large amount of data. In this paper, the proposed DWT(Discrete Wavelet Transform) filter bank is consisted of simple architecture, but it is efficiently designed that a user obtain a wanted compression rate as only input parameter. If it is implemented by FPGA chip, the designed encoder operates in 12MHz.

• Proceedings of the Technology Innovation Conference
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• 1999.12a
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• pp.240-254
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• 1999

In the knowledge-based society of the new millenium, major countries have implemented computer literacy. Recently the Korean government announced 'CyberKorea21'and established 5 year information & communication technology development plan. In Canada, project CANARIE represents a contribution to building the communications infrastructure of the high-speed communications networks of the 21st century. Countries around the world are looking to Canada as the model for Internet research network(Ca*net3) and 'connecting Canadian'. The purpose of this paper is on the strategic implications through comparative analysis of computer literacy between Canada and Korea.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2248-2251
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• 2003

Communication between speech networks employing different speech codecs requires interoperability. The cascade connection of two different codecs, called tandem coding, not only degrades speech quality, but also produces high computational loads. These Problems can be solved by using the transcoding algorithm. This paper presents an effective algorithm for transcoding from G.729A to EVRC and its simulation results.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1991.11a
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• pp.249-260
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• 1991

위성 통신망은 도청의 위협이 가장 큰 통신망으로 사용자들의 민감한 정보에 대한 프라이버시의 보호가 어려운 통신망이다. 또한 위성통신의 고유한 특성상 위성체를 원격지에서 제어해야 하므로 위성 제어 신호에 대한 안전한 인증(authentication) 메카니즘이 필요하다. 본 연구에서는 공용 위성 통신망에서 사용자의 프라이버시를 위한 암호시스템과 위성 제어 신호의 안전한 인증 메카니즘을 제시하고자 한다.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.105-125
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• 2005

Motivated by the field experimental designs in agriculture, the theory of block designs has been applied to several areas such as statistics, combinatorics, communication networks, distributed systems, cryptography, etc. An explicit formula and its fast computational algorithm for a class of symmetric balanced incomplete block designs are presented. Based on the formula and the careful investigation of the modulus multiplication table, the algorithm is developed. The computational costs of the algorithm is superior to those of the conventional ones.

• International Journal of Contents
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• v.2 no.1
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• pp.1-4
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• 2006

E-business is not like e-commerce. E-business is more comprehensive than e-commerce. In the near future, it is expected that ebusiness prevails in the fields of wireless, peer-to-peer networks, streaming media and biometrics technologies. In this paper, we discuss the past and current of e-business, and then research topics of e-business, including new technology and the directions.

• Proceedings of the CALSEC Conference
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• 2004.02a
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• pp.271-284
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• 2004

Rapid developments in computing and communication technology have made broadband Internet service over the wireless phone networks possible. This so-called 3G (third generation) mobile services promise to usher us into an era of a seamless marriage between Internet data and mobile phone services. However,

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.615-617
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• 2012

최근 이동통신 인프라 기술은 고용량 전송이 가능한 LTE 이동 통신 시스템이 구축되었다. 따라서 3G 이동통신 시스템에 비해 서비스 용량에 비해 입체영상을 이동통신 시스템에서 실시간으로 전송할 수 있는 고용량의 무선 링크를 확보하였다. 하지만 LTE 이동 통신 시스템도 입체영상을 그대로 전송하기에는 문제점을 가지고 있다. 따라서 본 논문에서는 차세대 이동통신 시스템인 LTE 시스템과 WiFi 네트워크 기반의 고품질의 입체영상을 전송하기 위한 전송 서비스 네트워크 모델을 고찰한다.