• Photonics industry news
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• s.16
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• pp.46-53
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• 2003

• NEWSLETTER 전기공업
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• no.98-10 s.203
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• pp.26-36
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• 1998

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.140-142
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• 2019

이 연구에서는 재난문자에서의 외국어 제공 현황에 대해 알아보았다. 우선, 뉴스를 분석한 결과, 외국인들은 국내 재난문자의 문제점으로 한국어라는 언어 제공 한정을 꼽았다. 다음으로, 미국은 WEA 규정에 따라 영어 외에 스페인어로 된 경고 메시지를 지원해야 하는 것으로 나타났다. WEA에서의 다국어 제공을 위한 다양한 노력도 하고 있었다. 마지막으로, 일본은 이동통신사 차원에서 다국어 재난문자를 지원하고 있는 것으로 나타났다. NTT DOCOMO는 외국인을 위해 일본어 재난문자를 영어, 중국어, 한국어로 번역해 주는 기능을 제공하고 있었다. KDDI도 NTT DOCOMO가 제공하는 언어 외에 포르투칼어, 스페인어도 제공하고 있었다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.574-578
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• 2006

유비쿼터스 컴퓨팅 환경에서는 센서를 통하여 실시간의 상황인식 서비스를 제공하며, 이를 위해 사용자의 위치 정보 수집이 필요하다. NTT에서는 RFID에 대한 익명화를 통한 프라이버시보호 메커니즘을 제안하였다. 그러나, 불법적으로 접근하는 리더가 존재할 경우 i값의 비동기화를 통한 태그에 대한 Random Tampering공격이 가능하다. 본 논문에서는 NTT 연구소의 RFID 익명화 방법을 개선하여 태그의 Random Tampering 공격 방지가 가능하고, 태그와 리더 상호간 인증이 가능하며, 연산 과정을 절감시킨 새로운 RFID 익명화 프로토콜을 제안한다. 제안한 방법을 통하여 보다 안전하고 효율적으로 RFID기반 센서 네트워크 환경에서 사용자의 프라이버시를 보호할 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06b
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• pp.29-34
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• 1996

This paper proposes a new concept in video called Graphical Video. Graphical Video is a content-based and scalable video representation. A video consists of several elements such as moving images, still images, graphics, characters and charts. All of these elements can be represented graphically except moving images. It is desirable to transform these moving images graphical elements so that they can be treated in the same way as other graphical elements. To achieve this, we propose a new graphical representation of moving images using spatio-temporal clusters, which consist of texture and contours. The texture is described by three-dimensional fractal coefficients, while the contours are described by polygons. We propose a method that gives domain pool location and size as a means to describe cluster texture within or near a region of clusters. Results of an experiment on texture quality confirm that the method provides sufficiently high SNR as compared to that in the original three-dimensional fractal approximation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1016-1021
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• 1999

In order to obtain a demodulated signal from RZ-SSB signal, it is important to design a linearizer which cancels the high-order distortions after FM demodulation. Since the NTT's linearizer must include a Hilbert transform, the characteristics of the linearizer are determined by the characteristics of Hilbert transform and it is very complicated to design and realize especially in the low frequency range. In the case of the proposed linearizer, the high-order distortion can be reduced without using any Hilbert transform. Furthemore, unlike the conventional RZ-SSB Demodulator, the proposed linearizer can be realized easily.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.662-666
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• 2002

Carrier Pre-Selection (CPS) was introduced to Japan in May 1, 2001. CPS reduced telephone charges from minimum of 3.4% to maximum of 12%. But due to competitive marketing by telecommunication companies like NTT, KDDI and Japan Telecom, resulted reduction of revenue.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1132-1136
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• 2014

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

• NEWSLETTER 전기공업
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• no.98-23 s.216
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• pp.18-30
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• 1998

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.319.2-320
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• 2001