• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.191-193
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• 2019

ISO/IEC JTC1 WG11 Moving Picture Expers Group 과 ITU-T SC16 은 Joint Video Experts Team 을 구성하여 차세대 비디오 부호화 표준으로서 Versatile Video Coding(VVC)를 표준화 중이다. VVC 는 현재 블록의 화면내 예측 모드일 가능성이 높은 모드의 집합인 Most Probable Mode(MPM) 리스트를 유도하고, MPM 을 이용하여 효율적으로 화면내 예측 모드를 부호화한다. VVC 참조 소프트웨어는 주변 블록의 화면내 예측 모드가 일치하는지 여부에 따라 1 개 또는 2 개의 모드를 최종 후보 선택을 위한 과정인 Rate-Distortion Optimization(RDO) 과정에 추가한다. 하지만 현재 MPM 은 항상 첫 번째 후보로 Planar 모드가 위치하며 이로 인하여, 주변 블록의 화면내 예측 모드가 RDO 에 추가되지 않는 경우가 존재한다. 따라서 본 논문은 VVC 의 부호화기에서 주변 블록의 화면내 예측 모드가 고려되지 않는 경우가 존재하는 문제를 해결하기 위한 방법을 제안한다. 제안 방법은 MPM 유도 과정에서 RDO 에 포함할 후보의 개수를 수정하여 RDO 과정에 항상 주변 블록의 화면내 예측 모드가 추가되도록 한다. 본 논문은 실험을 통해 제안 방법이 약 0.04%의 부호화 효율을 향상시켰음을 보인다.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1380-1385
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• 2020

An annular linear induction electromagnetic pump (ALIP) which has a developed pressure of 0.76 bar and a flow rate of 100 L/min is designed to analysis end effect which is main problem to use ALIP in thermohydraulic system of the prototype generation-IV sodium-cooled fast reactor (PGSFR). Because there is no moving part which is directly in contact with the liquid, such as the impeller of a mechanical pump, an ALIP is one of the best options for transporting sodium, considering the high temperature and reactivity of liquid sodium. For the analysis of an ALIP, some of the most important characteristics are the electromagnetic properties such as the magnetic field, current density, and the Lorentz force. These electromagnetic properties not only affect the performance of an ALIP, but they additionally influence the end effect. The end effect is caused by distortion to the electromagnetic field at both ends of an ALIP, influencing both the flow stability and developed pressure. The electromagnetic field distribution in an ALIP is analyzed in this study by solving Maxwell's equations and using numerical analysis.

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.193-198
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• 2009

The H.264/ AVC video coding standard supports the intra prediction with various block sizes for luma component and a 8x8 block size for chroma components. This new feature of H.264/AVC offers a considerably higher improvement in coding efficiency compared to previous compression standards. In order to achieve this, H.264/AVC uses the Rate-distortion optimization (RDO) technique to select the best intra prediction mode for each block size, and it brings about the drastic increase of the computation complexity of H.264 encoder. In this paper, a fast block size decision algorithm is proposed to reduce the computation complexity of the intra prediction in H.264/AVC. The proposed algorithm computes the smoothness based on AC and DC coefficient energy for macroblocks and compares with the nonparametric criteria which is determined by considering information on neighbor blocks already reconstructed, so that deciding the best probable block size for the intra prediction. Also, the use of non-parametric criteria makes the performance of intra-coding not be dependent on types of video sequences. The experimental results show that the proposed algorithm is able to reduce up to 30% of the whole encoding time with a negligible loss in PSNR and bitrates and provides the stable performance regardless types of video sequences.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.360-363
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• 2018

Human activity is influenced by various factors, from individual physical features such as vertebral flexion and pelvic distortion to feelings such as joy, anger, and sadness. However, the nature of these behaviors changes over time, and behavioral characteristics do not change much in the short term. The activity data of a person has a time series characteristic that changes with time and a certain regularity for each action. In this study, we applied LSTM, a kind of cyclic neural network to deal with time - series characteristics, to the technique of recognizing activity type and improved recognition rate of activity type by measuring time and parameter optimization of components of LSTM model.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.849-857
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• 2011

Gaming on demand(GOD) makes people enjoy games by encoding and transmitting game screen at a server side, and decoding the video at a client side. In this paper, we propose a fast game video encoder for multiple users over network with low-powered devices. In the proposed system, the computational complexity of game encoders is reduced by using scene descriptors, which consists of an object motion vector, global motion, and scene change. With additional information from game engines, the proposed encoder does not need to perform various complexity processes such as motion estimation and ratedistortion optimization. The motion estimation and rate-distortion optimization skipped by scene descriptors. We found that the proposed method improved 192 % in terms of FPS, compared with x264 software. With partial assembly code, we also improved coding speed by 86 % in terms of FPS. We found that the proposed fast encoder could encode over 60 FPS for real-time GOD applications.

• Smart Media Journal
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• v.3 no.4
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• pp.16-21
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• 2014

HEVC is the latest joint video coding standard with ITU-T SG16 WP and ISO/IEC JTC1/SC29/WG11. Its coding efficiency is about two times compared to H.264 high profile. Intra prediction has 35 directional modes including dc and planer. However an accurate mode decision on lots of modes with SSE is too costly to implement it with hardware. The key idea of this paper is a DCT shared architecture to reduce the complexity of HEVC intra encoder. It is to use same DCT block to quantize as well as to calculate SSE in RDO. The proposed intra encoder uses two step mode decision to lighten complexity with simplified RDO blocks and shares the transform resources. Its BD-rate increase is negligible at 20% on hardware aspect and the operating clock frequency is 300MHz@60fps on FHD ($1920{\times}1080$) image.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.102-110
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• 2010

H.264 SVC(Scalable Video Coding) provides the advantages of low disk storage requirement and high scalability. However, a streaming server or a user terminal has to extract a bit stream from SVC file. This paper proposes a bit stream extraction method which can get the maximum PSNR value while date bit rate does not exceed the available network bandwidth. To do this, this paper obtains the information about extraction points which can get the maximum PSNR value offline and decides the spatial/temporal resolution of a bit stream at run-time. This resolution information along with available network bandwidth is used as the parameters to a bit stream extractor. Through experiment with JSVM reference software, we proved that proposed bit stream extraction method can get a higher PSNR value.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.925-931
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• 2008

In video coding standard H.264/AVC, variable block size mode algorithm improves compression efficiency but has need of a large amount of computation for various block modes and mode decision. Meanwhile, decided inter block modes depend on the complexity of a block image, and then the more complex a macroblock is, the smaller its block size is. This paper proposes fast inter block mode decision algorithm. It limits valid block modes to the block modes with a great chance for decision using the image complexity and carries out motion estimation rate-distortion optimization with only the valid block modes. In addition to that, it applies fast motion estimation PDE to the valid block modes with only the $16{\times}16$ block mode. The reference software JM 9.5 was executed to estimate the proposed algorithm's performance. The simulation results showed that the proposed algorithm could save about 24.12% of the averaged motion estimation time while keeping the image quality and the bit rate to be -0.02dB and -0.12% on the average, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10C
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• pp.820-828
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• 2008

In order to achieve high coding efficiency, H.264/AVC video coding standard adopts the techniques such as variable block size coding, motion estimation with quarter-pel precision, multiple reference frames, rate-distortion optimization, and etc. However, these coding methods have a defect to greatly increase the complexity for motion estimation. Particularly, from multiple reference frame motion estimation, the computational burden increases in proportion to the number of the searched reference frames. Therefore, we propose the method to reduce the complexity by controlling the number of the searched reference frames in motion estimation. Proposed algorithm uses the optimal reference frame information in both $P16{\times}16$ mode and the adjacent blocks, thus omits unnecessary searching process in the rest of inter modes. Experimental results show the proposed method can save an average of 57.31% of the coding time with negligible quality and bit-rate difference. This method also can be adopted with any of the existing motion estimation algorithm. Therefore, additional performance improvement can be obtained.

• The Journal of the Korea Contents Association
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• v.15 no.2
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• pp.1-10
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• 2015

In this paper, we propose an integral image compression method to improve the coding efficiency. As the characteristics of integral images are various according to the distance between a camera and objects, complexity of the objects and background, etc, the coding efficiency can be improved by applying a coding method adaptive to the characteristics. In addition, as the integral images are compressed by the unit of elemental images, the coding efficiency can be improved. by employing a coding method optimized to the coding direction of elemental images. Therefore, the proposed method remaps an integral image with six kinds of mapping rules, and then the conventional 3D-DCT based compression method is applied to the remapped images. Finally, we perform the rate-distortion optimization to choose the best of the mapping rules. Experimental results show that the proposed method yields high gains in image quality and bit-rate.