• 전자공학회논문지CI
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• 제49권2호
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• pp.123-133
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• 2012

본 논문에서는 DNA 시퀀스의 불법 복제 및 변이 방지와 개인 정보 침해 방지, 또는 인증을 위한 DNA 워터마킹에 대하여 논의하며, 변이에 강인하고 아미노산 보존성을 가지는 부호영역 DNA 시퀀스 기반 DNA 워터마킹 기법을 제안한다. 제안한 DNA 워터마킹은 부호 영역의 코돈 서열에서 정규 특이점에 해당되는 코돈들을 삽입 대상으로 선택되며, 워터마크된 코돈이 원본 코돈과 동일한 아미노산으로 번역되도록 워터마크가 삽입된다. DNA 염기 서열은 4개의 문자 {A,G,C,T}로 (RNA은 {A,C,G,U}) 구성된 문자열이다. 제안한 방법에서는 워터마킹 신호처리에 적합한 코돈 부호 테이블을 설계하였으며, 이 테이블에 따라 코돈 서열들을 정수열로 변환한 다음 원형 각도 형태의 실수열로 재변환한다. 여기서 코돈은 3개의 염기들로 구성되며, 64개의 코돈들은 20개의 아미노산으로 번역된다. 선택된 코돈들은 아미노산 보존성을 가지는 원형 각도 실수 범위 내에서 인접 코돈과의 원형 거리차 기준으로 워터마크에 따라 변경된다. HEXA와 ANG 시퀀스를 이용한 $in$ $silico$ 실험을 통하여 제안한 방법이 기존 방법에 비하여 아미노산 보존성을 가지면서 침묵 변이와 미스센스 변이에 보다 강인함을 확인하였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2011년도 추계학술대회
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• pp.310-313
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• 2011

This study investigates some schemes to estimate the coding efficiency of a video sequence. The texture complexity and motion are considered as two major parameters to decide the coding efficiency, and the methods to estimate the parameters are discussed. For a fixed values of PSNR, the bit rate of a video sequence is estimated using some schemes based on the estimated parameters, and compared with the bit rate by MPEG-4 AVC.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.117-120
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• 2002

In this paper, we propose a new text watermarking method using space coding and PN sequence. A PN sequence generated from user message modifies the space between words in each line. The detection can be done without original text image using the average space with in the text. Experimental results show that proposed method has the invisible property and robustness to the attack such as the elimination of words in the text.

• 한국군사과학기술학회지
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• 제11권5호
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• pp.23-33
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• 2008

In this paper, we verify the performance of LDPC coded OFDM/DS system by Monte-Carlo simulation of BER on Eb/No. The simulation results show that LDPC coded OFDM/DS has a strong anti-jamming characteristic over pulse-noise jammer and partial-band noise jammer. The performance of LDPC coded OFDM/DS system is evaluated on both faded waveforms and non-faded waveforms. For non-faded waveforms, high coding gain is attained due to LDPC, even when waveforms have short PN sequence and JSR is only 5dB. Especially, the increase in the repeated number of LDPC decoding enhances coding gain. However, faded waveforms cannot achieve sufficient average effect when PN sequence is short. High coding gain of faded waveforms can be achieved by extending length of PN sequence. In addition, we compare LDPC coded OFDM/DS system with Convolutional coded OFDM/DS system. The simulation results illustrate that when LDPC coded OFDM/DS system with short PN sequence has sufficient average effects, the system shows lower BER than Convolutional coded OFDM/DS system with long PN sequence.

• 반도체디스플레이기술학회지
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• 제5권2호
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• pp.19-25
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• 2006

This paper focuses on lossy medical image compression methods for medical images that operate on three-dimensional(3-D) irreversible integer wavelet transform. We offer an application of unbalanced tree structure algorithm to medical images, using a 3-D unbalanced wavelet decomposition and a 3-D unbalanced spatial dependence tree. The wavelet decomposition is accomplished with integer wavelet filters implemented with the lifting method. We have tested our encoder on volumetric medical images using different integer filters and coding unit sizes. The coding unit sizes of 16 slices save considerable dynamic memory(RAM) and coding delay from full sequence coding units used in previous works. If we allow the formation of trees of different lengths, then we can accomodate more transaxial scales than three. The encoder and decoder can then keep track of the length of the tree in which each pixel resides through the sequence of decompositions. Results show that, even with these small coding units, our algorithm with certain filters performs as well and better in lossy coding than previous coding systems using 3-D integer unbalanced wavelet transforms on volumetric medical images.

• BMB Reports
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• 제37권2호
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• pp.144-147
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• 2004

Molecular amplification and sequencing of genomic DNA that encodes camel polyubiquitin (PUBC1) was performed by a polymerase chain reaction (PCR) using various sets of primers. The amplification generated a number of DNA fragments, which were sequenced and compared with the polyubiquitin coding sequences of various species. One DNA fragment that conformed to 325 bp was found to be 95 and 88% homologous to the sequences of human polyubiquitin B and C, respectively. The DNA translated into 108 amino acids that corresponded to two fused units of ubiquitin with no intervening sequence, which indicates that it is a polyubiquitin and contains at least two units of ubiquitin. Although, variations were found in the nucleotide sequence when compared to those of other species, the amino acid sequence was 100% homologous to the polyubiquitin sequences of humans, mice, and rats. This is the first report of the polyubiquitin DNA coding sequence and its corresponding amino acid sequence from camels, amplified using direct genomic DNA preparations.

• 방송공학회논문지
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• 제10권4호통권29호
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• pp.463-473
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• 2005

본 논문에서는 JVT에서 표준화가 진행중인 스케일러블 동영상 부호화의 부호화 효율을 높이기 위해 영상 시퀀스의 시간적변환 특성을 고려하여 적응적으로 GOP의 크기를 선택하여 부호화를 하는 방법을 제안한다. 일반적으로 SVC에서는 한 영상 시퀀스에 대해서 GOP의 크기를 고정하여 부호화를 하는데, GOP의 크기와 영상 시퀀스의 시간적 특성에 따라 부호화 효율이 변하게 된다. 이에 비디오 시퀀스의 지역적인 시간적 특성에 따라 GOP의 크기를 적응적으로 가변 하여 부호화하는 방식을 제안한다. 실험 결과 제안된 적응적 GOP 구조 (Adaptive GOP Structure) 부호화 방법의 부호화 효율이 개선되었으며, Crew 시퀀스에서는 0.63dB 가 향상되었다.

• Journal of Communications and Networks
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• 제1권3호
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• pp.182-188
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• 1999

The optimal joint maximum-likelihood sequence estima-for using an array of antennas is derived for synchronous direct sequence-code division multiple access (DS-CDMA) system. Each user employs a rate 1/n convolutional code for channel coding for the additive white Gaussian noise (AWGN) channel. The array re-ceiver structure is composed of beamformers in the users' direc-tions followed by a bank of matched filters. The decoder is imple-mented using a Viterbi algorithm whose states depend on the num-ber of users and the constraint length of the convolutional code. The asymptotic array multiuser coding gain(AAMCG)is defined to encompass the asymptotic multiuser coding gain and the spatial information on users' locations in the system. We derive the upper and lower bounds of the AAMCG. As an example, the upper and lower bounds of AAMCG are obtained for the two user case where each user employes the maximum free distance convolutional code with rate 1/2. The enar-far resistance property is also investigated considering the number of antenna elements and user separations in the space.

• 한국정보통신학회논문지
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• 제9권5호
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• pp.1019-1024
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• 2005

MPEG-2로 부호화 된 영상에서 발생하는 전송 오류는 화질의 열화를 가져오고, 시공간적으로 오류를 전파시킨다. 특히 비디오 비트열에서 헤더 정보의 오류는 복호화 과정 전체에 영향을 미치므로 데이터 정보의 오류와 달리 전체 영상에 심각한 화질의 열화를 일으킬 수 있다. 따라서 헤더 정보에서의 오류를 복원하는 것은 데이터 정보에서 오류를 복원하는 것보다 더 중요하다. 본 논문에서는 LSB(least significant bit) 부호화를 이용하여 헤더 정보를 양자화 된 DCT(discrete cosine transform) 계수에 반복적으로 삽입하여 전송함으로써 MPEG-2의 신택스 구조 그대로 유지하면서 헤더 정보의 오류를 복원할 수 있는 방법을 제안한다.

• ETRI Journal
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• 제27권6호
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• pp.713-724
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• 2005

This paper focuses on the problem of key-frames coding and proposes a new promising approach based on the use of fractals. The summary, made of a set of key-frames selected from a full-length video sequence, is coded by using a 3D fractal scheme. This allows the video presentation tool to expand the video sequence in a "natural" way by using the property of the fractals to reproduce the signal at several resolutions. This feature represents an important novelty of this work with respect to the alternative approaches, which mainly focus on the compression ratio without taking into account the presentation aspect of the video summary. In devising the coding scheme, we have taken care of the computational complexity inherent in fractal coding. Accordingly, the key-frames are first wavelet transformed, and the fractal coding is then applied to each subband to reduce the search range. Experimental results show the effectiveness of the proposed approach.