• Journal of Power Electronics
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• v.18 no.2
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• pp.364-374
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• 2018

A novel passive lossless soft-switching single inductor dual buck full-bridge inverter (PLSSIDBFBI) is presented in this paper. To accomplish this, a passive lossless snubber circuit is added to a dual buck full-bridge inverter. Therefore, the advantages of the dual buck full-bridge inverter are included in the proposed inverter, and the inverter has just one filter inductor, which can decrease the system volume and improve the integration. In addition, the passive lossless snubber circuit achieves soft-switching by its own resonance, and all of the energy stored in the passive lossless snubber circuit can be transferred to load. A comparison between eight topologies is performed in this paper, and the analysis shows that the proposed soft-switching inverter topology has high reliability and efficiency. Finally, experimental results obtained with a 1 kW prototype verify the theoretical analysis and demonstrate the prominent characteristics of a reduced switching loss and improved efficiency.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.349-356
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• 1997

In this paper, we propose the lossless coding: scheme for progressive transmission of medical images. The input image is decomposed by the proposed fast adaptive subband decomposition method which is suited for a lossless coding. The decomposed images are coded by an arithmetic coder with two conditioning pixels, and the conditioning pixels are selected differently according to the property of the subbands. The conditioning contexts are usually quantized to reduce the conditional state, and the optimization method of quantization is proposed For the purpose of improving compression ratio in this paper. The proposed lossless coding scheme provides the asymmetric structure of cosec and results in better compression ability than the JPEC lossless coding[ 1 ].

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.3
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• pp.124-130
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• 2006

A wavelet-based image compression system allowing both lossless and lossy image compression is proposed in this paper. The proposed algorithm consists of the two stages. The first stage uses the wavelet packet transform and the quad-tree coding scheme for the lossy compression. In the second stage, the residue image taken between the original image and the lossy reconstruction image is coded for the lossless image compression by using the integer wavelet transform and the context based predictive technique with feedback error. The proposed wavelet-based algorithm, allowing an optional lossless reconstruction of a given image, transmits progressively image materials and chooses an appropriate wavelet filter in each stage. The lossy compression result of the proposed algorithm improves up to the maximum 1 dB PSNR performance of the high frequency image, compared to that of JPEG-2000 algorithm and that of S+P algorithm. In addition, the lossless compression result of the proposed algorithm improves up to the maximum 0.39 compression rates of the high frequency image, compared to that of the existing algorithm.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.307-315
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• 2014

A new modified lossless intra-coding method based on a cross residual transform is applied to HEVC(High Efficiency Video Coding). The HEVC standard including a multi-directional spatial prediction method to reduce spatial redundancy encodes the pixels in a PU (Prediction Unit) by using neighboring pixels. In the new modified lossless intra-coding method, the spatial prediction is performed by pixel-based DPCM but is implemented by block-based manner by using cross residual transform on the HEVC standard. The experimental results show that the new lossless intra-coding method reduces the bit rate of approximately 8.4% in comparison with the lossless-intra coding method in the HEVC standard and the proposed method results in slightly better compression ratio than the JPEG2000 lossless coding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2254-2260
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• 2010

This papers describes modification of the integer transform used in H.264/AVC in order to efficiently apply to lossless compression. The previous reversible integer transform is not efficient for lossless compression due to large dynamic range of the transform coefficients. To reduce the problem, efficient and reversible integer transforms are proposed. The modified transforms are designed based on the lifting scheme for fast transforms. This paper introduces signal flow graphs for the proposed fast transforms and provides corresponding experimental results. The results indicate that the proposed modified reversible integer transform are superior to the previous transform in terms of lossless compression efficiency.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.65-72
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• 1994

We resolve the suboptimal $\infty$ control problem using (J,J')-lossless coprime factorization by transforming the linear fractional transformation (LFT) into chain scattering description (CSD) in discrete-time systems. The condition transformed LFT into CSD is that the inverse matrix of $P_{21}$ of standard plant exists. But, this paper presents the method of transforming LFT into CSD for 4-block problem in case that the inverse matrix of $P_{21}$ of standard plant does not exist and parameterization of the all suboptimal $\infty$T controllers using (J,J')-lossless coprime factorization. It is shown that this method can resolve the suboptimal $\infty$ control problem solving only two Riccati equations in discrete-time systems.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.478-484
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• 2004

In this paper, two lossless snubber cells are proposed to generalize high frequency converter with losslless snubber. The selecting of snubber cells, which generalize high frequency converters, are depended on converter topologies. The cells have a saturable inductor, LC resonant tank and two diodes. In the cells, the saturable inductors extremely reduce resonant energy in the LC resonant tank. By minimizing resonant energy, the converter, which applies snubber cells, can operate at high frequency. These cells are applied for Buck, Boost, Buck-Boost, Cuk, ZETA, and SEPIC to generalize converter which have lossless snubber. The boost type converter has been implemented, with 400 kHz switching frequency for 125 W load to verify the converter characteristics.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.299-302
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• 2000

최근에 새로운 텍스트 압축방법인 BWT(Burrows and Wheeler transformation)가 소개되었다. 이 변환은 우수한 텍스트 압축성능을 가지지만 텍스트와 영상의 다른 성질로 인해 영상에 직접 적용될 때 그다지 우수한 압축성능을 기대할 수 없다. 본 논문에서는L-SSKF(Lossless Symmetric Short Kernel Filter)를 사용하여 영상을 대역분할한 후에 BWT를 수행하여 무손실이면서 우수한 압축성능을 가지는 무손실 영상압축방법을 제안한다. 또한 압축성능의 향상을 위해 두과정의 중간에 화소예측방법인GAP(Gradient Adjusted Prediction)를 적용하여 성능개선을 비교하였다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.285-290
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• 2009

In this paper, we propose a new algorithm that improves the lossless data compression rate. The proposed algorithm lessens the redundancy and improves the compression rate evolutionarily around 40 up to 80 percentile depending on the characteristics of binary images used for compression. In order to demonstrate the superiority of the proposed method, the comparison between the proposed method and the LZ78 (LZ77) is demonstrated through experimental results theoretical analysis.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.31-33
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• 2005

In this paper, a design of lossless hybrid-type magnetic levitation system is presented. The lossless hybrid-type system is implemented by a permanent-magnet and electro-magnetic system. The target plant consists of eight hybrid-type magnets and at steady-state, no current is needed to support the load. The design procedure is described and the results of this work are shown.