• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.877-881
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• 2002

Digital contents such as image need both secure proving and publicly verification scheme on embedded digital watermark for contents distribution and copyright protection. Specially, we must provide publicly verification mechanism on digital watermark without revealing any of the secret information hidden on digital contents. In this paper, we review on the existing zero knowledge proofs and digital watermarking system, and propose advanced interactive zero knowledge proofs mechanism for enhancing the performance and security of watermark verification process. And it Provides a new watermark verification scheme without revealing any secret on the contents owner's copyright in formation.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2008-2010
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• 2003

본 논문은 디지털 재설계 기법을 이용한 PWM 제어기 설계 기법을 제안한다. 디지털 재설계 기법은 잘설계된 아날로그 제어기의 성능을 보장하도록 변환하는 기법이다. 재설계된 디지털 제어기는 등가 영역의 법칙을 사용하여 PWM 제어기로 변환한다. 제안된 기법의 효용성을 검증하기 위하여 인공위성의 자세제어 시스템의 모의실험의 예를 보인다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.90-96
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• 2014

This paper presents a practical linearization technique for a wide-band bang-bang digital phase locked-loop(BBDPLL) by selecting optimal loop gains. In this paper, limitation of the theoretical design method for BBDPLL is explained, and introduced how to implement practical BBDPLLs with CMOS process. In the proposed BBDPLL, the limited cycle noise is removed by reducing the proportional gain while increasing the integer array and dither gain. Comparing to the conventional BBDPLL, the proposed one shows a small area, low power, linear characteristic. Moreover, the proposed design technique can control a loop bandwidth of the BBDPLL. Performance of the proposed BBDPLL is verified using CppSim simulator.

• Journal of KIISE
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• v.45 no.3
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• pp.311-320
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• 2018

Recently, the use of digital audio and video as proof in criminal and all kinds of litigation is increasing, and scientific investigation using digital forensic technique is developing. With the development of computing and file editing technologies, anyone can simply manipulate video files, and the number of cases of manipulating digital data is increasing. As a result, the integrity of the evidence and the reliability of the evidence Is required. In this paper, we propose a technique for extracting the Electrical Network Frequency (ENF) through a grid of power grids according to the geographical environment for power supply, and then performing signal processing for peak detection using QIFFT. Through the detection algorithm using the standard deviation, it was confirmed that the video file was falsified with 73% accuracy and the forgery point was found.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.912-917
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• 2004

The increase of illegal usage and conflict in digital content market would diminish motivation of creators for their work, furthermore break down digital content market on cyber-space. Watermarking technology support to the legal users by the protection technique based on the digital content copyright protection method(DRM). Most of previous digital watermarking have embeded to the content. In this paper, we propose a wavelet based watermarking method which is used for implementing in the frequency domain.

• The Journal of the Acoustical Society of Korea
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• v.36 no.2
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• pp.123-129
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• 2017

In this paper, the realization of a directional digital hearing aid was considered. Conventional time domain time delay method was replaced with digital filters in order to make any general-purposed DSP (Digital Signal Processing) chip to produce the similar directivity pattern. Both the time delay algorithm and the digital filter algorithm were initially evaluated by Matlab (Matrix laboratory) for comparison, and it was confirmed by CSR 8675 Bluetooth DSP IC (Digital Signal Processing Integrated Circuit) chip firmware realization. Some remote control features by a smart phone was added to the smart hearing aid for user interface easiness.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.85-87
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• 2012

최근 모바일 기기는 물론 디지털 카메라, SNS의 발전으로 인하여 매일 방대한 양의 디지털 이미지가 생성된다. 따라서 효과적이고 신뢰도 있는 인덱싱 기법과 탐색 기법이 요구되고 있다. 이미지 태깅은 효과적이고 신뢰도 있는 이미지 탐색에 큰 연관관계가 있다. 본 연구에서는 여러가지 이미지 태깅 기법들을 서베이하고 자동 및 반 자동 이미지 태깅 기법들에 대하여 알아본다.

• Journal of the Korean Society for information Management
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• v.20 no.1
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• pp.5-29
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• 2003

University libraries have developed digital information resources for digital services and have tried to preserve valuable digital information. Because digital preservation raises challenges of a fundamentally different nature which we added to the problems to preserving traditional format materials, it is necessary that preserving digital resources must be discussed and researched actively. This study conducts risk management for exploring preserving technologies and assessing tools. It is found that most university libraries have used format conversion frequently and do not use the emulation technology. It is also found that medium refreshing has the lowest risk probability and isk impact, but information migration and emulation technology have the highest in the risk probability and in the risk impact individually and the absence of full-time professional staff causes high risk.

• Journal of KIISE:Databases
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• v.36 no.2
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• pp.63-72
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• 2009

Digital forensics refers to finding electronic evidences related to crimes. As cyber crimes are increasing daily, digital forensics for finding electronic evidences is also becoming important. At present, various aspects of digital forensics have being researched including the overall process model and analysis techniques such as network forensics, system forensics and database forensics for digital forensics. Regarding database forensics, only analysis techniques dependent on specific vendors have been suggested. And general process models and analysis techniques which can be used in various databases have not been studied. This paper proposes an integrated process model and analysis technique for database forensics. The proposed database forensics model (DFM) allows us to solve problems and analyze databases according to the situation and purpose, and to use a standard model and techniques for various database analyses. In order to test our model(DFM), we applied it to various database analyses. And we confirmed the results of our experiment that it can be applicable to acquisition in the scene as well as analysis of data relationships.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.83-91
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• 2005

The digital signature can be verified and disavowed only with cooperation of the signer in 'undeniable signature scheme. A signed confidential document of a company can be copied and delivered to a rival company. If a conventional signature scheme is used to sign the document, it can be confirmed as authentic by verifying the signature without the signer's cooperation. However, if the company doesn't want the document to be verified as authentic by the rival company, it is recommended to use the undeniable signature scheme. Convertible undeniable signature scheme has additional property that the signer can convert undeniable signature to the ordinary one. The document signed by undeniable signature scheme that is no longer confidential can be opened to public use by converting the signature to the ordinary one. In this study, the efficient multipurpose convertible undeniable signature scheme based on El-Gamal signature scheme is proposed. The proposed scheme satisfies undeniable property and can convert undeniable signature to the ordinary one. The number of public keys and signatures are less than those of Boyar's convertible signature scheme. It also reduces the number of communication steps of the signature confirmation protocol.