• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.97-102
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• 2000

Subband coding is to divide the signal frequency band into a set of uncorrelated frequency bands by filtering and then to encode each of these subbands using a bit allocation rationale matched to the signal energy in that subband. The actual coding of the subband signal can be done using waveform encoding techniques such as PCM, DPCM and vector quantizer(VQ) in order to obtain higher data compression. Most researchers have focused on the error in the quantizer, but not on the overall reconstruction error and its dependence on the filter bank. This paper provides a thorough analysis of subband codecs and further development of optimum filter bank design using vector quantizer. We compute the mean squared reconstruction error(MSE) which depends on N the number of entries in each code book, k the length of each code word, and on the filter bank coefficients. We form this MSE measure in terms of the equivalent quantization model and find the optimum FIR filter coefficients for each channel in the M-band structure for a given bit rate, given filter length, and given input signal correlation model. Specific design examples are worked out for 4-tap filter in 2-band paraunitary filter bank structure. These optimum paraunitary filter coefficients are obtained by using Monte Carlo simulation. We expect that the results of this work could be contributed to study on the optimum design of subband codecs using vector quantizer.

• Journal of Broadcast Engineering
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• v.15 no.3
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• pp.426-433
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• 2010

The H.264/AVC video coding standard performs inter prediction using variable block sizes to improve coding efficiency. Since we predict not only the motion of homogeneous regions but also the motion of non-homogeneous regions accurately using variable block sizes, we can reduce residual information effectively. However, each motion vector should be transmitted to the decoder. In low bit rate environments, motion vector information takes approximately 40% of the total bitstream. Thus, motion vector competition was proposed to reduce the amount of motion vector information. Since the size of the motion vector difference is reduced by motion vector competition, it requires only a small number of bits for motion vector information. However, we need to send the corresponding index of the best motion vector predictor for decoding. In this paper, we propose a new codeword table based on the phased-in code to encode the index of motion vector predictor efficiently. Experimental results show that the proposed algorithm reduces the average bit rate by 7.24% for similar PSNR values, and it improves the average image quality by 0.36dB at similar bit rates.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.178-184
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• 2013

In this paper, we propose an efficient parallelization technique of PU-level motion estimation (ME) in the next generation video coding standard, high efficiency video coding (HEVC) to reduce the time complexity of video encoding. It is difficult to encode video in real-time because ME has significant complexity (i.e., 80 percent at the encoder). In order to solve this problem, various techniques have been studied, and among them is the parallelization, which is carefully concerned in algorithm-level ME design. In this regard, merge estimation method using merge estimation region (MER) that enables ME to be designed in parallel has been proposed; but, parallel ME based on MER has still unconsidered problems to be implemented ideally in HEVC test model (HM). Therefore, we propose two strategies to implement stable parallel ME using MER in HM. Through experimental results, the excellence of our proposed methods is shown; the encoding time using the proposed method is reduced by 25.64 percent on average of that of HM which uses sequential ME.

• Biomedical Science Letters
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• v.6 no.1
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• pp.11-17
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• 2000

SNAP-25 was first investigated as a neuron-specific protein preferentially expressed in CA3 pyramidal neurons of mouse hippocampus. It is a presynaptic plasma membrane protein in the nerve cell and plays an important role in the synaptic vesicle membrane docking and fusion pathway. We have recently isolated SNAP-25 cDNA from a rat brain cDNA library using a probe of Z2 cDNA. It consisted of 2,101 bp and an open reading frame (ORF) was identified between nucleotides (nt) 209 and 827. The AUG codon (nt 209∼211) was surrounded by CTACCATGG, which corresponded to the consensus sequence of ribosomal binding site. The ORF was terminated by TAA (nt 827∼829) to encode a polypeptide of 206 amino acid residues. The 3'-untranslated region contained two extensive stretches of repeated (CA)28 and (CA)19 at positions 925∼980 and 1645∼1682. It is noteworthy that cysteine residues were clustered in the span of amino acid residues 84∼991 : Cys-Gly-Leu-Cys-Val-Cys-Pro-Cys. Rat SNAP-25 showed 88% and 97% identity in nucleotide sequences to that of human and mouse, respectively. Amino acid sequence of rat SNAP-25 showed 100% identity to that of mouse and human SNAP-21.

• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.33-38
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• 2008

DNA methylation is involved in tissue-specific gene control and essential for normal embryo development Octamer-binding transcription factor 4 (Oct-4) is one of the most important transcription factors for early differentiation. This study was performed whether the bovine Oct-4 is tissue specific or developmental dependent epigenetic mark, we investigated transcripts and the methylation status of CpGs of 5'-promoter region of Oct-4 in bovine preimplantation embryos. Oct-4 transcripts were highly detected in morula and blastocyst, while they were present low levels in sperm and 2- to 8-cell stage embryos. These results suggest that de novo expression of Oct-4 initiates at morula stage of embryogenesis. Here we determined that there is a tissue-dependent differentially methylated region (T-DMR) in the 5'-promoter region of Oct-4. The methylation status of the Oct-4 T-DMR was distinctively different in the oocyte from that in the sperm and adult somatic tissues and changed from zygote to blastocyst stage, suggesting that active methylation and demethylation occur during preimplantation development. Based on these results, the 5'-promoter region of Oct-4 gene is target for DNA methylation and the methylation status changes variously during embryonic development in bovine.

• Journal of Life Science
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• v.14 no.1
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• pp.21-25
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• 2004

To identify genes involved in the decolorization of both crystal violet and malachite green, we isolated random mutants generated by transposon insertion in triphenylmethane-decolorizing bacterium, Citrobacter sp. The resulting mutant bank yielded 14 mutants with complete defect in color removal capability of both crystal violet and malachite green. Southern hybridization with a Tn5 fragment as a probe showed a single hybridized band in 5 mutants and these mutants appeared to have insertions at different sites of the chromosome. Tn5-inserted genes were isolated and the DNA sequence flanking Tn5 was determined. From comparison with a sequence database, putative protein products encoded by cmg genes were identified as follows. cmg 2 is MaIC protein in maltose transport system; cmg 6 is transcriptional regulator (LysR-type): cmg 12 is a putative oxidoreductase. The sequences deduced from two cmg genes, cmg 8 and cmg 11, showed no significant similarity to any protein with a known function. Therefore, these results indicate that these two cmg genes encode unidentified proteins responsible for decolorization of both crystal violet and malachite green.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.93-97
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• 2008

RraA is a recently discovered protein inhibitor that regulates the enzymatic activity of RNase E, which plays a major role in the decay and processing of RNAs in Escherichia coli. It has also been shown to regulate the activity of RNase ES, a functional Streptomyces coelicolor ortholog of RNase E, which has 36% identity to the amino-terminal region of RNase E. There are two open reading frames in S. coelicolor genome that can potentially encode proteins having more than 35.4% similarity to the amino acid sequence of RraA. DNA fragment encoding one of these RraA orthologs, designated as RraAS2 here, was amplified and cloned in to E. coli vector to test whether it has ability to regulate RNase E activity in E. coli cells. Co-expression of RraAS2 partially rescued E. coli cells over-producing RNase E from growth arrest, although not as efficiently as RraA, induced by the increased ribonucleolytic activity in the cells. The copy number of ColEl-type plasmid in these cells was also decreased by 14% compared to that in cells over-producing RNase E only, indicating the ability of RraAS2 to inhibit RNase E action on RNA I. We observed that the expression level of RraAS2 was lower than that of RraA by 4.2 folds under the same culture condition, suggesting that because of inefficient expression of RraAS2 in E. coli cells, co-expression of RraAS2 was not efficiently able to inhibit RNase E activity to the level for proper processing and decay of all RNA species that is required to restore normal cellular growth to the cells over-producing RNase E.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.122-126
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• 2010

RAD53 functions as an effector kinase of checkpoint pathways in Saccharomyces cerevisiae, which plays a central role to regulate many downstream cellular processes in response to DNA damage. It also involves in transcriptional activation of various genes including RNR genes which encode the key enzyme required for dNTP synthesis. In this study, we identified CYC8 as a suppressor for the hydroxyurea sensitivity of $rad53{\Delta}$ mutation. $Rad53{\Delta}$ mutant transformed with a multi-copy plasmid containing CYC8 showed increased hydroxyurea resistance. In contrast, TUP1 which forms a complex with CYC8 did not function as a suppressor. In the case of mutations, both $cyc8{\Delta}$ and $tup1{\Delta}$ suppressed hydroxyurea sensitivity of $rad53{\Delta}$. Since CYC8 can propagate as a prion in yeast, overexpression of CYC8 induced misfolding of the normal CYC8 proteins, resulting in dominant cyc8-phenotype. Therefore, it is suggested that CYC8 can act as a multi-copy suppressor due to its prion property. It was observed that the levels of RNR transcription were increased in the yeast strains containing either multi-copies of CYC8 gene or $cyc8{\Delta}$ mutation, suggesting that the increased level of RNR will elevate the intracellular pools of dNTPs, which, in turn, suppress the phenotype of $rad53{\Delta}$ mutation.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.523-530
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• 1999

Sal enteritidis thin fimbriae, SEF14, were found to be restricted to the predominantly poultry-associated members of the Salmonella serogroup D1 that are considered as the important pathogens in poultry industry. SefA together with sefB and sefC encode the proteins involved in SEF14 biosynthesis. In order to develop the rapid and specific detection methods for Salmonella serogroup D1, a PCR technique for the amplification of sefA gene was established, and its specificity and sensitivity were investigated with various microorganisms. The bacterial genomic DNA was extracted by colony-picking and rapid boiled-lysate technique. In comparison of Sef I and Sef II primers used in the PCR, Sef I primer for sefA gene of 513bp showed higher specificity than that of Sef II. The established PCR was as sensitive as to detect 1pg of Sal enteritidis DNA. When 73 strains in 28 genera including the reference strains and the field isolates of various Salmonella serotypes, Bacillus subtilis, Bordetella bronchisepdca, E coli, Listeria spp., Micrococcus luteus, Rhodococcus equi, Staphylococcus spp., Streptococcus spp., Vibrio parahemolyticus, Yersinia spp. were studied, the established PCR yielded specifically positive results with only Salmonella serogroup D1. The results suggested that the PCR for sefA gene could be a potential candidate among the specific detection methods for Salmonella serogroup D1.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.273-278
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• 2000

The aacCl, aacC2, aacC3, and aacC4 genes, which encode aminoglycoside acetyltransferase AAC(3)-I, AA(3)-II, AAC(3)-III, and AAC(3)-IV, respectively, and aerolysin genes in water samples from Juam lake were surveyed by polymerase chain reaction. Surface water was collected from January 1996 to December 1998, and then bacterial DNA was extracted from the water. Twelve samples were tested by PCR to servey the genes for aminoglycoside acetyltransferase and aerolysin in the lake water. The aacC2 gene was detected in 9 of 12 DNA samples. Among 9 samples showing aacC2 positive, 7 samples were associated with Tn3 sequence. However, none of the twelve samples amplified the expected DNA fragment for aacC1, aacC3, and aacC4 genes. PCR primer to detect the aerolysin gene was designed using the conserved region of the genes for aerolysin and hemolysin of Aeromonas spp. This primer set successfully amplified the expected 414 bp PCR product with the DNA samples from the lake water. The aerolysin gene was detected in 7 of 12 DNA samples. When Southern hybridization of the gel with probe was performed, the aerolysin gene was detected in 10 of 12 DNA samples. However, the seasonal fluctuation of these genes was not found.