• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.413-421
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• 2005

As the population of HDTV is growing, among many useful features of modern set top boxes (STBs) or digital video recorders (DVRs), video browsing, visual bookmark, and picture-in-picture capabilities are very frequently required. These features typically employ reduced-size versions of video frames, or thumbnail images. Most thumbnail generation approaches generate DC images directly from a compressed video stream. A discrete cosine transform (DCT) coefficient for which the frequency is zero in both dimensions in a compressed block is called a DC coefficient and is simply used to construct a DC image. If a block has been encoded with field DCT, a few AC coefficients are needed to generate the DC image in addition to a DC coefficient. However, the bit length of a codeword coded with variable length coding (VLC) cannot be determined until the previous VLC codeword has been decoded, thus it is required that all codewords should be fully decoded regardless of their necessary for DC image generation. In this paper, we propose a method especially for fast DC image generation from an I-frame using multiple-symbol lookup table (mLUT). The experimental results show that the method using the mLUT improves the performance greatly by reducing LUT count by 50$\%$.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.2
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• pp.35-55
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• 2022

As altmetrics has received a lot of attention as an muti-dimensional impact assessment tool, it is necessary to verify whether it can supplement the citation-based research performance evaluation system. This study analyzed and compared the effects of each altmetrics sources on citation by sampling 1,600 high-cited papers published in the last 10 years (Sample A) and non-year-limited papers (Sample B) indexed in Scopus. In addition, it was analyzed whether the OA of the paper had a moderating effect on the numbers of cited-by, and the difference according to the samples was verified. As a result of the analysis, only the number of Mendeley bookmark readers was analyzed to have a positive (+) effect on the numbers of cited-by, and OA status had a significant moderating effect in both groups. However, in sample A, OA showed a reinforcing effect on cited-by, whereas Sample B showed a weakening effect, showing a difference. On the other hand, social mention such as media reports do not have a significant effect on the cited-by regardless of OA conditions, but they can be used to understand the social impact of non-academic mass readers.