• Macromolecular Research
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• v.13 no.5
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• pp.427-434
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• 2005

To improve the performance and reduce raw material costs, blocked isocyanates were prepared with mixture of blocking agents in many industries. Three blocked isocyanates (adducts) namely $\varepsilon$-caprolactam/benzotriazole-blocked 4,4'-diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI) and 4,4'-dicyclohexyl-methane diisocyanate ($H_{12}$MDI) were synthesized. Six reference adducts were also prepared by blocking MDI, TDI, and $H_{12}$MDI with $\varepsilon$-caprolactam ($\varepsilon$-CL) or benzotriazole. The reactions were carried out in acetone medium and dibutyltin dilaurate (DBTDL) was used as a catalyst. The progress of the blocking reaction was monitored by IR spectroscopy. De-blocking temperatures (dissociation temperatures) of these adducts were studied using DSC and TGA and the results were correlated. As expected, the thermal analysis data showed that de-blocking temperature of blocked aromatic isocyanates was lower than that of the blocked aliphatic isocyanates. The low de-blocking temperature of blocked aromatic isocyanate could be due to electron withdrawing benzene ring present in the blocked isocyanates. It was also found that benzotriazole-blocked adducts de-blocked at higher temperature compared with $\varepsilon$-CL-blocked adducts.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.513-526
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• 2010

In this paper, we propose a de-blocking filter for improvement of coding efficiency and computational complexity reduction on a high definition video coding. Recently, the H.264/AVC standard-based research for high definition video coding method is under way because the amount of used of high definition videos is on the increase. The H.264/AVC de-blocking filter is designed for low bitrate video coding and it improves not only the subjective quality but also coding efficiency by minimizing the blocking artifact. However, the H.264/AVC de-blocking filter that strong filtering is performed is not suitable in a high definition video coding which occurs relatively low blocking artifact. Also, the conventional de-blocking filter has high computational complexity in decoder side. The computational complexity of the proposed method is reduced about maximum 8.8% than conventional method. Furthermore, the coding efficiency of the proposed method is about maximum 7.3% better than H.264/AVC de-blocking filter.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.41-52
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• 2011

It is important to reduce computational complexity of de-blocking filter for real-time implementation, because it accounts for a great part of total computational complexity of the decoder. Because there are a lot of conditional branches and memory accesses in a decoding loop, it is not easy to speed up the de-blocking filter. Therefore, this paper presents a new algorithm of de-blocking filter minimizing conditional branches and memory accesses. The proposed structure of de-blocking filter enables filter operation to parallelize by software pipelining. The proposed optimization method was implemented on a TMS320DM6467 EVM board and we achieved approximately 46% cycle reduction, compared with that of FFmpeg.

• Journal of Computational Design and Engineering
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• v.3 no.4
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• pp.295-311
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• 2016

This paper addresses to the flowshop scheduling problem with blocking constraints. The objective is to minimize the makespan criterion. We propose a hybrid combinatorial particle swarm optimization algorithm (HCPSO) as a resolution technique for solving this problem. At the initialization, different priority rules are exploited. Experimental study and statistical analysis were performed to select the most adapted one for this problem. Then, the swarm behavior is tested for solving a combinatorial optimization problem such as a sequencing problem under constraints. Finally, an iterated local search algorithm based on probabilistic perturbation is sequentially introduced to the particle swarm optimization algorithm for improving the quality of solution. The computational results show that our approach is able to improve several best known solutions of the literature. In fact, 76 solutions among 120 were improved. Moreover, HCPSO outperforms the compared methods in terms of quality of solutions in short time requirements. Also, the performance of the proposed approach is evaluated according to a real-world industrial problem.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.555-559
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• 2007

국제 비디오 압축 표준인 H.264/AVC는 MPEG-2나 MPEG-4등에 비해 압축률이 2배 이상 향상되어 저대역폭을 가지는 모바일 단말기 기반의 네트워크에서도 이전의 압축표준보다 훨씬 좋은 품질의 영상을 제공하나 높아진 압축률에 상응하여 복잡도 또한 증가하였다. 이러한 복잡도를 해결하기 위하여 디코딩을 하는 과정에서 병목현상을 일으키는 부분들을 하드웨어의 최적화된 설계로 해결해왔다. 이러한 하드웨어 기반 해결은 단말기의 교체라는 단점을 가지고 있다. 이러한 단점을 해결하기 위하여 본 논문에서는 소프트웨어 디코더가 모바일 단말기에 적용되기 위한 조건들을 살펴보고 디코딩 과정 중에 가장 많은 병목 현상을 가지는 디블록킹 필터(De-Blocking Filter)를 모바일 단말기에 적용하기 위한 방법을 제안한다. 이러한 시도는 모바일 단말기 상에서 하드웨어 기반 디코더가 아닌 소프트웨어 기반 디코더가 구현 될 수 있는 기초가 된다.

• ETRI Journal
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• v.32 no.4
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• pp.622-625
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• 2010

In this letter, we assess the scalability of a path computation flooding (PCF) approach to compute optimal end-to-end inter-domain paths in a path computation element-based multi-domain network. PCF yields a drastically reduced network blocking probability compared to a blind per-domain path computation but introduces significant network control overhead and path computation complexity. In view of this, we introduce and compare an alternative low overhead PCF (LoPCF) solution. From the obtained results, LoPCF leads to similar blocking probabilities to PCF while exhibiting around 50% path computation complexity and network control overhead reduction.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.284-289
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• 2008

H.264/AVC among moving picture compression standard is the standard format for high compression rate and reliable video transimission. It generates blocking effects in video due to compressing video using block-based DCT and includes de-blocking filter to reduce blocking effect. Therefore, the filter makes the video over-smoothing and the quality of it is reduced. In this paper, we propose a improved de-blocking filter to solve the demerit. The proposed de-blocking filter redetermine the block boundary strength and apply the comer filtering to eliminate artifacts in low frequency domain. To evaluate the performance, we apply the proposed deblocking filter and exiting method to various video and evaluated the quality of image subjectively and objectively by analyzing the result. The simulation result shows the proposed method preserves the edge of video, reduces blocking effects and improves PSNR than the existing method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.505-513
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• 2004

Most video codecs including the international standards use the block-based hybrid structure for efficient compression. But for low bit-rate applications such as video transmission through wireless channels, the blocking artifacts degrade image qualify seriously. In this paper, we propose an adaptive de-blocking algorithm using characteristics of the block boundaries. Blocking artifacts contain the high frequency components near the block boundaries, therefore the lowpass filtering can remove them. However, simple lowpass filtering results into blurring by removing important information such as edges. To overcome this problem, we determine the modes depending upon the characteristics of pixels adjacent to block boundary then proper filter is applied to each area. Simulation results show that proposed method improves de-blocking performance compared to that of MPEG-4.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.1
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• pp.47-53
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• 2008

Blocking artefact noise is necessarily happened in compressed images using block-coded algorithms such as JPEC compressing algorithm. This noise is more recognizable especially in highly compressed images. In this paper, an algorithm is presented for reduction of blocking artefact noise using block division. Furthermore, we also mention about the median filter which is often used in image processing.

• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.313-320
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• 2017

The In-loop filtering methods such as de-blocking filter and SAO(Sample Adaptive Offset) applied to the HEVC standard achieves coding efficiency and subjective quality improvement by reducing the blocking artifacts and the ringing artifacts. However, despite the use of In-loop filtering methods, the artifacts called a corner outlier occurring at the corner points of block boundaries are not removed. In this paper, the corner outlier artifacts are reduced by the detection, determination, and filtering processes on the corner outlier pixels. Experimental results show that the proposed method improves the subjective picture quality and slightly increases the coding efficiency in Inter prediction.