• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.599-608
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• 2013

Motion compensated interpolation (MCI) techniques are used for increasing the frame rate and generating the side information in the distributed video coding (DVC) system. In this paper, an efficient MCI technique using the image resizing in the DCT or LiftLT domain is proposed, and the performance of the MCI technique using various sub-pixel generation techniques is analyzed. Extensive computer simulations show that the proposed method produces the superior results compared to the conventional methods.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.1
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• pp.13-23
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• 2020

In this paper, we propose a quantization parameter determination method for face depth image encoding in order to minimize an impact on a face recognition accuracy. When a face depth image is compressed through quantization in H.264/AVC, differential quantization parameters are assigned according to an accuracy of ellipsoid modeling prediction and an importance degree of a unit block in extracting facial features. The simulation results show that the face recognition success rates are improved by up to 6% at the same compression rates through the proposed compression rate determination method.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.489-496
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• 2015

In this paper, a new weighted prediction scheme is proposed to improve the coding efficiency for video scenes containing brightness variations. Conventional weighted prediction is applied by the reference picture and use only one weighted parameter set. Thus, it is only useful for GBV(Glabal Brightness Variation). In order to solve this problem, the proposed algorithm use three kind of schemes depending on situation. Experimental results show that maximum coding efficiency gain of the proposed method is up to 10.2% in luminance. Average computional time complexity is increased about 163% in encoder and about 101% in decoder.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2645-2652
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• 1996

In this paper wepropose a sub-block retransmission scheme for ARQ and hybrid ARQ schemes. When the cannel is quiet the sub-block retransmission scheme behaves like a conventional ARQ or hybrid ARQ scheme. As the channel is becoming noisy, the data block is dvided into small sub-blocks for transmission. Each sub-block is encoded for error control by an apprpriate shortened code and the code length of the shortened code is being adaptive to the corresponding channel BER. the reeived block is checked for errors sub-block by sub-block. The propsoed sub-block retransmission scheme provides improved throughput over conventional schemes by retransmitting only the naked sub-blocks in the occurrence of errors. An example of transferring ATM cells is considered for simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2A
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• pp.165-172
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• 2002

The concept of MPEG-2 transcoding is related to the scaling the bit rate of the previously encoded MPEG bitstream. We proposed a new rate control algorithm that outperforms existing methods and showed the performance by a computer simulation. A rate-quatization model is developed based on a priori knowledge from the given bitstream at macroblock level. The model is independent of the picture coding type, because it is designed in the DCT domain. To increase the accuracy of the model, the activity measurement is considered. By the simulation, the proposed transcoding showed the better result than that of recoding by TM5. We also concluded that MPEG-2 scalable profile is not suitable for the bit rate conversion application.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.45-51
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• 2003

JPEG200, a new international standard for still image compression based on wavelet and bit-plane coding techniques, is developed. In this paper, we design the DWT(Discrete Wavelet Transform) and quantizer for JPEG2000 CODEC. DWT handles both lossy and lossless compression using the same transform-based framework: The Daubechies 9/7 and 5/3 transforms, and quantizer is implemented as SQ(Scalar Quantization). The architecture of the proposed DWT and SQ are synthesized and verified using Xilinx FPGA technology. It operates up to 30MHz, and executes algorithms of wavelet transform and quantization for VGA 10 frame per second.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.258-258
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• 2016

이상기후로 인한 자연 재해의 발생규모는 점차 증가하고 있다. 이는 시민의 안전과 재산을 위협하는 요인 중 하나이며, 시민 개인의 안전 침해 뿐 아니라 국가적 재산에 해당하는 SOC 시설물의 위협 역시 심각한 피해라고 할 수 있다. 이를 위해 최근 SOC 시설물에 대한 재난 대응 측면의 모니터링 시스템을 구축 및 개발 하고 있으며, 그를 지원하는 현장 지원 모바일 시스템을 연계하는 방안을 모색하는 연구가 급증 하고 있다. 하지만 현장에 있는 시설물 담당자의 측면에서는 실시간으로 모니터링 시스템을 신속하게 활용할 수 없으며, 모듈 단위가 융합하여 구동되는 무거운 사양의 시스템이 일반 PC에서 원활이 구동될 것이라는 보장이 없다. 따라서 본 연구에서는, 재난시에 발생할 수 있는 SOC 시설물에 대한 피해정보를 시뮬레이션 해주는 3차원 표출 시스템과, 그에 대한 일반 정보를 간단하게 확인 할 수 있는 모바일 어플리케이션 간의 원활한 연계 방안을 모색하고자 한다. 재난 정보는 지리정보 뿐 아니라 지리정보와 연계되는 다양한 정보들이 융합되어 있어 그에 대한 원 데이터를 실시간으로 모바일 상에 전송할 수 없으며, 이를 단순화 시킨 정보를 전송해야할 필요성이 있다. 따라서 본 연구에서는 해당하는 정보를 영상화 및 압축 하여 보다 신속하고 효율적으로 정보를 받아볼 수 있도록 하는 체계를 수립하고, 그에 맞는 시스템을 설계하고자 한다. 이를 기반으로 효율적인 재난 정보 압축방안을 마련하며, 향후 신속한 정보 송 수신 체계를 확보할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.726-732
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• 2003

The paper proposes a motion estimation (ME) technique to reduce computational complexity. It is achieved by skipping ME process for macro-blocks decided to be in no need of the operation. Thus, it is called ME skipping technique(MEST). In general, the ME is composed of integer pixel precision ME (IME) followed by half pixel precision ME (HME). The MEST is performed just before an IME process and makes a decision on skipping the IME process according to a criterion based on ME errors of adjacent macro-blocks (MBs) already encoded. When the IME process for a MB is decided to be skipped, which is called ME skip mode, the IME process is skipped and the integer pixel precision motion vector of the MB is just replaced by a predicted vector and used as the input of HME. On the other hands, the IME processes for MBs in ME non-skip mode are not skipped but normally performed. Accordingly, the MEST is very effective to reduce computational complexity when MBs in ME skip mode is abundant. In addition, when the MEST is applied to video encoder, it contributes to more accurate rate control and more robusaess for channel errors. It is experimentally shown that the MEST has the above advantages while maintaining good reconstructed image quality.

• Journal of Broadcast Engineering
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• v.11 no.1 s.30
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• pp.116-129
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• 2006

The progress of data transmission technology through the Internet has spread a variety of realistic contents. One of such contents is multi-view video that is acquired from multiple camera sensors. In general, the multi-view video processing requires encoders and decoders as many as the number of cameras, and thus the processing complexity results in difficulties of practical implementation. To solve for this problem, this paper considers a simple multi-view system utilizing a single encoder and a single decoder. In the encoder side, input multi-view YUV sequences are combined on GOP units by a video mixer. Then, the mixed sequence is compressed by a single H.264/AVC encoder. The decoding is composed of a single decoder and a scheduler controling the decoding process. The goal of the scheduler is to assign approximately identical number of decoded frames to each view sequence by estimating the decoder utilization of a Gap and subsequently applying frame skip algorithms. Furthermore, in the frame skip, efficient frame selection algorithms are studied for H.264/AVC baseline and main profiles based upon a cost function that is related to perceived video quality. Our proposed method has been performed on various multi-view test sequences adopted by MPEG 3DAV. Experimental results show that approximately identical decoder utilization is achieved for each view sequence so that each view sequence is fairly displayed. As well, the performance of the proposed method is examined in terms of bit-rate and PSNR using a rate-distortion curve.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.46-54
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• 2011

In this paper, we propose a low-complexity loop filtering method depending on transform-block regions. Block adaptive loop filter (BALF) was developed to improve about 10% in compression performance for the next generation video coding. The BALF employs the Wiener filter that makes reconstructed frames close to the original ones and transmits filter-related information. However, the BALF requires high computational complexity, while it can achieve high compression performance because the block adaptive loop filter is applied to all the pixels in blocks. The proposed method is a new loop filter that classifies pixels in a block into inner and boundary regions based on the characteristics of the integer transform and derives optimum filters for each region. Then, it applies the selected filters for the inner and/or boundary regions. The decoder complexity can be adjusted by selecting region-dependent filter to be used in the decoder side. We found that the proposed algorithm can reduce 35.5% of computational complexity with 2.56% of compression loss, in case that only boundary filter is used.