• 한국정보통신학회논문지
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• 제5권3호
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• pp.405-417
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• 2001

본 논문에서는 현재 사용하고 있는 아날로그 방식의 감시 시스템에서 발생하는 자원 낭비와 효율성 저하 문제를 극복하기 위해 MPEG-2 국제 표준을 이용한 영상 데이터의 인코딩 기법과 압축 기법을 적용한 새로운 방식의 디지털 감시 시스템의 설계 및 구현 기법에 대해 기술하였다. 또한, 기존의 디지털 감시 카메라 시스템에서 적용하지 못한 고속 움직임 추정 알고리듬을 적용하여, 보다 실시간적인 시스템을 제안한다. 고속 움직임 추정 알고리듬은 MPEG-2 비디오 인코딩을 위해서 제안되었다 이 알고리듬은 블록 매칭 기법과 그래디언트 기법의 혼합적인 사용에 기반한다. 또한 MPEG-2 비디오 데이터를 직접적으로 사용하여 움직이는 물체를 추출하는 방법을 제안하였다. 제안된 방법은 매우 간단하고 종래의 물체 검출 방법들 보다 계산 시간이 훨씬 덜 요구된 다. 본 논문에서 제안한 시스템은 특정한 하드웨어 없이 단지 소프트웨어만으로 영상데이터를 실시간으로 인코딩 및 디코딩 한다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권5호
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• pp.443-450
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• 2013

This paper propose a new ROM data encoding method that takes into account of a sequential access pattern to reduce the power consumption in ROMs used in applications such as FIR filters that access the ROM sequentially. In the proposed encoding method, the number of 1's, of which the increment leads to the increase of the power consumption, is reduced by applying an exclusive-or (XOR) operation to a bit pair composed of two consecutive bits in a bit line. The encoded data can be decoded by using XOR gates and D flip-flops, which are usually used in digital systems for synchronization and glitch suppression. By applying the proposed encoding method to coefficient ROMs of FIR filters designed by using various design methods, we can achieve average reduction of 43.7% over the unencoded original data in the power consumption, which is larger reduction than those achieved by previous methods.

• 한국멀티미디어학회논문지
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• 제24권4호
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• pp.558-568
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• 2021

The digital image to be accepted as legal evidence, it is important to verify the authentication of the digital image. This study proposes a method of authenticating digital images through three steps of comparing the file structure of digital images taken with iPhone, analyzing the encoding information as well as media logs of the iPhone storing the digital images. For the experiment, digital image samples were acquired from nine iPhones through a camera application built into the iPhone. And the characteristics of file structure and media log were compared between digital images generated on the iPhone and digital images edited through a variety of image editing tools. As a result of examining those registered during the digital image creation process, it was confirmed that differences from the original characteristics occurred in file structure and media logs when manipulating digital images on the iPhone, and digital images take with the iPhone. In this way, it shows that it can prove its forensic authentication in iPhone.

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.97-103
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• 2010

We propose a new technique for the optical encryption of gray-level optical images digitized into 8-bits binary data by ASCII encoding followed by QPSK modulation. We made an encrypted digital hologram with a security key by using 2-step phase-shifting digital holography, and the encrypted digital hologram is recorded on a CCD camera with 256 gray-level quantized intensities. With these encrypted digital holograms, the phase values are reconstructed by the same security key and are decrypted into the original gray-level optical image by demodulation and decoding. Simulation results show that the proposed method can be used for cryptosystems and security systems.

• International Journal of Knowledge Content Development & Technology
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• 제8권3호
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• pp.53-67
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• 2018

Local languages based information storage and retrieval system is essential for any online digital repository system. This paper reports the development of an interface in Bengali that allows users not only browsing and searching Indic-script based documents but also allows administrator performing various system level operations. This paper briefly describes the origin and key characteristics of Indic-scripts along with their encoding in Unicode standard with special reference to Bengali language. It also demonstrates the development processes of Bengal-script based information representation and retrieval (IRR) system viz. BURA (Burdwan University Research Archive) using different open standard and open source software (OSS) including different factors essential for building such successful Indic-script based multilingual digital libraries. The suggested strategies may help digital library developers to design an appropriate multi-script based information access services in any other Indic-script based languages.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2001년도 종합학술발표회논문집
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• pp.464-468
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• 2001

In this paper, we propose a robust watermarking technique that accepts time scaling, pitch shift, add noise and a lot of lossy compression such as MP3, AAC, WMA. The technique is developed based on digital filtering. Being designed according to critical band of HAS (human auditory system), the digital filters nearly affect audio quality. Furthermore, before implementing digital filtering, wavelet transform decomposes the audio signal into several signals that is composed of specific frequencies. Designed digital filters scan the decomposed signal. The designed digital filter, band-stop filter, distorts and eliminates specific frequencies of audio signals. Watermarking detection can be accomplished by FFT (Fast Fourier Transform). Firstly, segments of audio signal are transformed by FFT. Then, the obtained amplitude spectrum by FFT is summed repeatedly. Finally the watermark detector can find filters used to watermark encoding based on eliminating frequencies. The suggested technique can embed 4bits/s in a robust manner.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.152-155
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• 2002

In this paper, a new approach is proposed for the error detection dedicated to MPEG-4 video coding by using the digital watermarking. In the process of encoding, the proposed scheme abstracts the macroblock features of headers, motion vectors, and Discrete Cosine Transform (DCT) coefficients, which are embedded in the quantized DCT coefficients as the digital watermarks. The decoder performs the accurate error detection through the watermark extraction. Simulation results demonstrate that the error detection ability of the proposed approach can be significantly enhanced, and that digital watermark embedding incurs little degradation to the picture quality.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권2호
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• pp.115-121
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• 2002

This paper presents an evolutionary design of digital IIR filters using the genetic algorithm (GA) with modified genetic operators and real-valued encoding. Conventional digital IIR filter design methods involve algebraic transformations of the transfer function of an analog low-pass filter (LPF) that satisfies prescribed filter specifications. Other types of frequency-selective digital fillers as high-pass (HPF), band-pass (BPF), and band-stop (BSF) filters are obtained by appropriate transformations of a prototype low-pass filter. In the GA-based digital IIR filter design scheme, filter coefficients are represented as a set of real-valued genes in a chromosome. Each chromosome represents the structure and weights of an individual filter. GA directly finds the coefficients of the desired filter transfer function through genetic search fur given filter specifications of minimum filter order. Crossover and mutation operators are selected to ensure the stability of resulting IIR filters. Other types of filters can be found independently from the filter specifications, not from algebraic transformations.

• 정보처리학회논문지B
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• 제9B권6호
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• pp.715-726
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• 2002

이 논문에서는 범용 DSP칩인 ADSP2181를 사용하여 프랙탈 알고리즘 기반의 영상 부호화기를 설계 제작하였다. 제작된 부호화기는 고정소수점을 지원하는 Analog Device사의 ADSP2181 두 개를 사용하여 구현되었고, 영상부호화는 3단계의 파이프라인 구조에 의해 이루어진다. 첫 번째 파이프라인단인 영상 획득부는 NTSC표준 영상 신호로부터 디지털 영상 데이터를 획득하여 프레임 메모리에 저장한다. 두 번째 단에서의 주제어부에서는 영상 데이터를 프랙탈 알고리즘을 이용하여 부호화를 수행한다. 마지막 단인 출력 제어부는 부호화된 영상 계수를 RS422 포트를 통하여 출력하도록 한다. 설계 제작된 프랙탈 영상 부호화기의 성능은 QCIF 영상 포맷에서 정지영상에 대하여 초당 10프레임 이상의 부호화 속도를 얻었다. 프랙탈 알고리즘을 이용하여 프레임간 중복성을 이용한 영상 부호화시에는 초당 평균 30 프레임 이상의 부호화속도를 얻을 수 있었다.

• 한국정보통신학회논문지
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• 제19권5호
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• pp.1180-1188
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• 2015

본 논문에서는 프레넬릿 변환을 이용하여 디지털 홀로그램을 압축할 경우에 사용될 수 있는 쿼드트리 형태의 부대역 양자화기를 제안한다. 획득된 디지털 홀로그램에 대해서 프레넬릿 변환을 수행한 후에 각 부대역별로 화소당 평균 에너지와 부대역의 시각적인 중요도를 분석하여 부대역이 복원 영상에 비치는 영상을 분석하였다. 각 부대역별로 계수들의 분포를 분석하여 다이나믹 영역을 정하고, 부대역 양자화기를 설계하였다. 설계한 양자화기의 효율을 높이기 위해서 다이나믹 영역 외의 영역에 존재하는 계수를 활용하는 방법을 적용하였고, 이를 예외 계수라 하였다. 그 결과 σ′ = 5.0인 범위에서 높은 성능을 가질 수 있는 양자화기를 설계하였다.