• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2000.11a
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• pp.91-91
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• 2000

• Information and Communications Magazine
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• v.32 no.6
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• pp.23-29
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• 2015

오류 정정 부호(error-correcting code)를 사용하는 McEliece 암호 체계는 양자 컴퓨터에서도 안전한 공개키 암호기법으로서 주목 받아왔다. 본고에서는 McEliece 암호 체계에 사용되는 오류 정정 부호와 그 조건, 암호 체계의 구조와 그 발전 과정 및 응용을 알아보고, 안전성 분석에 대해 소개한다.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.49-55
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• 2016

This paper proposes an adaptive video signal transmission scheme in order to ensure the QoS (Quality of Service) of user requirements. SVC (Scalable Video Coding) is an effective transmission scheme, because that can transmit video signal according to the video layer's weight. However, in previous works, those adaptive transmission systems which are considered about the various channel environments and user requirements have not been insufficiently studied. So, we propose the SVC signal transmission using inter-layer differential OVSF code allocation scheme in MC-CDMA. The proposed scheme is able to obtain each layer signal's protection order and control the sub-block of MC-CDMA by feedback information from receiver. Therefore, our proposed scheme is possible to provide the video quality for each users according to variable channel environments. The simulation results demonstrate the enhancement of proposed system in terms of BER performance.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.28-36
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• 1999

An efficient inverse design method based on the MGM(Modified Garabedian-McFadden) method has been developed. The 2-D Navier-Stokes equations are solved for obtaining the surface pressure distributions and coupled with the MGM method to perform the inverse design. The MGM method is a residual-correction technique, in which the residuals are the difference between the desired and the computed pressure distribution. The developed code was applied to several airfoil shapes and the propeller. It has been found that they are well converged to their targeting shapes.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.127-131
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• 2007

This study was designed to demonstrate the ability of Texas Eye Research and Technology Center Dry Eye Questionaire (TERTC-DEQ) to examine the distribution of self-reported dry eye symptoms and their diurnal intensity in university students and compare it with McMonnies & Ho DEQ. Two dry eye questionnaires were administered to 46 contact lens wearers and 47 nonwearers. Contact lens wearers scored higher on the TERTC-DEQ (52.2%) than McMonnies & Ho DEQ (6.5%). Non-contact lens wearers also scored higher on the TERTC-DEQ (19.1%) than McMonnies & Ho DEQ (2.1%). Ocular symptoms worsened with progression of time of day in both groups of subjects. This study suggests that TERTC-DEQ provides a first-choice diagnosis tool to obtain a comprehensive assessment of patient's symptoms, especially in comparison with McMonnies & Ho DEQ. The TERTC-DEQ is an efficient screening survey and may be use in dry eye diagnosis of contact lens-related dry eye.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.688-692
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• 2001

본 논문에서는 무선 통신로 환경에서 발생하는 페이딩 현상과 전자기기에서 방출되는 임펄스성 전자간섭파에 따른 MC DS-CDMA와 DS-CDMA 시스템의 성능을 비교 분석하였다. 결과에 의하면, 페이딩과 임펄스 전자간섭파에 의해 시스템에 심각한 영향을 미치게 되는데 특히, 직접파 성분이 존재하는 페이딩 보다는 임펄스 전자간섭파의 발생빈도와 크기에 따라 두 시스템 성능이 크게 좌우됨을 알 수 있었다. 이에 대한 성능개선 기법으로 다이버시티 기법과 BCH(15, 7) 부호화 기법을 적용하여 직접파가 존재하는 페이딩과 강한 임펄스 간섭 환경에서도 만족할 만한 성능을 얻을 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.228-236
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• 2006

A Multicarrier code division multiple access(MC-CDMA) is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading effect and can support higher rate data transmission with higher spectral efficiency. The objective of this article is proposed and analyzed a new asynchronous MC-CDMA system with various kinds of data rates which employs a multiple access interference (MAI) canceller. The proposed multirate MC-CDMA system can be accomplished by changing the number of Parallel branch(P) according to their data rate and hybrid interference canceller(HIC) are used for MAI cancellation. We compare the performance of proposed system in terms of average bit error rate(BER) with that of a single rate MC-CDMA system. The results show the large improvement in performance that can be attained by the cancellation scheme under multipath environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.851-859
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• 2008

This paper investigates the effect a guard period (GP) in the form of a cyclic prefix for asynchronous multicarrier-code division multiple access (MC-CDMA) systems. At first, we analyze the performance of asynchronous MC-CDMA systems with a GP, which results in closed-form bit error rate (BER) performance. Furthermore, it confirms that the frequency diversity of MC-CDMA systems is identical to the path diversity. The analytical approach proposed here is extended to the case without a GP. The derived analytical results show that a GP is required for MC-CDMA systems in order to mitigate not only the effect of intersymbol interference (ISI) and intercarrier interference (ICI) but also the desired signal power degradation. In addition, the accuracy of the proposed analysis is verified by simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.390-396
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• 2009

MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of PSAM MC-DS-CDMA system with the application of STBC antenna diversity is analyzed. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation ernr, carrier frequency offset, and the nonlinear high power amplifier.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.47-54
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• 2019

In this paper, we consider a constant modulus (CM) based blind adaptive receiver design for downlink multi-carrier code-division multiple access (MC-CDMA) systems employing simple space-time block coding (STBC). In the paper, filter weight vectors used for the detection of the transmitted symbols are partitioned into its subvectors and then, special relations among the optimal subvectors minimizing the CM metric are derived. Using the special relations, we present a modified CM metric and propose a new blind adaptive stochastic-gradient CM algorithm (SG-CMA) by minimizing the modified CM metric. The proposed blind adaptive SG-CMA has faster convergence rate than the conventional SG-CMA because the filter weight vectors of the proposed scheme are updated in the region of satisfying the derived special relations. Computer simulation results are given to verify the superiority of the proposed SG-CMA.