• IEIE Transactions on Smart Processing and Computing
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• v.3 no.6
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• pp.388-392
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• 2014

This paper proposes an early termination method of a block vector search for fast encoding of high efficiency video coding (HEVC) screen content coding (SCC). In the proposed algorithm, two blocks indicated by two block vector predictors (BVPs) were first employed as an intra block copy (IBC) search. If the sum of absolute difference (SAD) value of the block is less than a threshold defined empirically, an IBC BV search is terminated early. The initial threshold for early termination is derived by statistical analysis and it can be modified adaptively based on a quantization parameter (QP). The proposed algorithm is evaluated on SCM-2.0 under all intra (AI) coding configurations. Experimental results show that the proposed algorithm reduces IBC BV search time by 29.23% on average while the average BD-rate loss is 0.41% under the HEVC SCC common test conditions (CTC).

• Journal of IKEEE
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• v.20 no.3
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• pp.273-278
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• 2016

In HEVC variable block size motion estimation, same search window data are duplicatedly used in each block size. It increases memory bandwidth, and it is difficult to exploit early termination. In this paper, largest block size and its corresponding smaller block sizes with same positions are performed at the same time. It reduces memory bandwidth and computation by reusing search window data and computation results. In the early termination, image quality can be degraded when it determines early termination by observing largest block size only, since smaller block sizes cannot be equally terminated due to their relative positions. So, in this paper, processing order of early termination is changed to perform smaller block sizes in turns. The designed motion estimation engine was described in Verilog HDL and it was synthesized and verified in 0.18um process technology. Its gate count and maximum operating frequency are 36,101 gates and 263.15 MHz, respectively.

• Journal of IKEEE
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• v.20 no.1
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• pp.111-114
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• 2016

In HEVC, motion estimation is performed independently for each variable block size. So it requires several times of search window data, and also it is difficult to exploit early termination. In this paper, a new method is proposed to exploit search window data and early termination in variable block size. When applied to TZS algorithm, it reduces pixel comparison and search window data accesses to 1/3.7 ~ 1/2.9 with negligible image quality degradation.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.4
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• pp.235-242
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• 2016

The emerging High-Efficiency Video Coding (HEVC) standard attempts to improve coding efficiency by a factor of two over H.264/Advanced Video Coding (AVC) at the expense of an increase in computational complexity. Mode decision with motion estimation (ME) is still one of the most time-consuming computations in HEVC, as it is with H.264/AVC. Thus, fast mode decisions are not only an important issue to be researched, but also an urgent one. Several schemes for fast mode decisions have been presented in reference software and in other studies. However, the conventional hierarchical mode decision can be useless when block-level parallelism is exploited. This paper proposes operation-level exploration that offers more chances for early termination. An early termination condition is checked between integer and fractional MEs and between the parts of one partition type. The fast decision points of the proposed algorithm do not overlap those in previous works. Thus, the proposed algorithms are easily used with other fast algorithms, and consequently, independent speed-up is possible.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.118-120
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• 2006

최신 GPU는 일반 CPU보다 10배 이상 빠른 연산능력을 갖추고 있는데다가 사용자가 직접 프로그래밍 할 수 있기 때문에 이를 이용한 고속 볼륨 렌더링 알고리즘에 대한 연구가 활발하게 진행되고 있다. 그러나 스트림 프로세싱에 특화 돼있는 GPU의 특성상 early ray termination과 empty space skipping을 구현하는 것이 쉽지만은 않다. 특히 지금까지 제안됐던, 프록시 도형(proxy geometry)을 사용하는 볼륨 렌더링 알고리즘은 empty space skipping은 비교적 효율적으로 구현하지만 early ray termination의 지원은 상대적으로 미비했다. 본 논문에서는 스텐실 버퍼와 OpenGL 확장(extension)을 이용한 2-Pass 알고리즘을 통해서 early ray termination과 empty space skipping을 동시에 구현하는 방법을 제시하고, 그 성능을 측정했다.

• Korean Journal of Construction Engineering and Management
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• v.12 no.3
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• pp.121-130
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• 2011

Real option values of early termination payment for selected BTO PPI projects are studied using binomial models. Two cases of early termination payments are considered; an option with the condition of private participants' default, and an option without the condition. Values vary depending upon parameter values such as revenues, costs, discount rates, debt ratio, and volatility of revenues. For selected projects, the option values without the default condition are estimated as 1%~7% of total project costs, whereas the option values with the default condition are estimated as 0%~1.89% of total project cost. When actual revenues differ from the forecasted revenues, apparently the option values deviate from the values based upon the forecasted revenues. When actual revenues fall short of the forecasted revenues, the option values increase by a large amount whereas the option values decrease by a small amount in the opposite case. This implies that the option values can be quite bigger than the values based upon the forecasted revenue especially when the revenue forecast uncertainty is large. This study is expected to play an important role in improving the early termination payment option policy of the government in PPI projects in Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1031-1042
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• 2009

Due to liberalization in the early stage, mobile communications market has grown rapidly in the world. However, some dominant operators set higher termination call charges, and thus the market has been distorted and customer welfare has been reduced a lot. The regulation of mobile termination charges is one of key issues of most regulatory agencies in the world. According to the survey, the level of mobile termination charges are quite different from country to country. Why is it so different? This paper investigated the determinants affecting the mobile termination charges for 28 countries by considering country-specific, industry-specific, and regulatory-specific conditions. We found that some regulatory-specific conditions are the most important factors. The rate of pre-paid contract and period of regulation mostly affect the mobile termination charges.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.961-967
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• 2014

Raptor codes are a class of rateless codes originally designed for binary erasure channels. This paper presents a compact set of mathematical expressions for iterative soft decoding of raptor codes. In addition, an early termination scheme is employed, and it is embedded in a single algorithm with the formula. In the proposed algorithm, the performance is enhanced by adopting iterative decoding, both in each inner and outer code and in the concatenated code itself between the inner and outer codes. At the same time, the complexity is reduced by applying an efficient early termination scheme. Simulation results show that our proposed method can achieve better performance with reduced decoding complexity compared to the conventional schemes.

• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.354-362
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• 2012

Recently, High Efficiency Video Coding (HEVC) is under development jointly by MPEG and ITU-T for the next international video coding standard. Compared to the previous standards, HEVC supports variety of splitting units, such as coding unit (CU), prediction unit (PU), and transform unit (TU). Among them, it has been known that the recursive quadtree structure of CU can improve the coding efficiency while the encoding complexity is increased significantly. In this paper, a simple conditional probability to predict the early termination condition of recursive unit structure is introduced. The proposed conditional probability is estimated based on Bayes' formula from local statistics of rate-distortion costs in encoder. Experimental results show that the proposed method can reduce the total encoding time by about 32% according to the test configuration while the coding efficiency loss is 0.4%-0.5%. In addition, the encoding time can be reduced by 50% with 0.9% coding efficiency loss when the proposed method was used jointly with HM4.0 early CU termination algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8C
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• pp.522-528
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• 2011

The iterative detection and decoding (IDD) has been shown to dramatically improve the bit error rate (BER) performance of the multiple-input multiple-output (MIMO) communication systems. However, these techniques require a high computational complexity since it is required to compute the soft decisions for each bit. In this paper, we show IDD comprised of sphere decoder with low-density parity check (LDPC) codes and present the tree search strategy, called a layer symbol search (LSS), to obtain soft decisions with a low computational complexity. In addition, an adaptive early termination is proposed to reduce the computational complexity during an iteration between an inner sphere decoder and an outer LDPC decoder. It is shown that the proposed approach can achieve the performance similar to an existing algorithm with 70% lower computational complexity compared to the conventional algorithms.