• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.833-840
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• 1987

A new Block Truncation Coding(BTC) technique reducing the bit-plane and using differential pulse code modulation (DPCM) is proposed and compared with the conventional BTC methods. A new technique decides whether the subblock can be approximated to be uniform or not. If the subblock can be approximated to be uniform(merge mode), we transmit only the gray-level informantion. It not (split mode), we transmity both the bit-plane and the gray-level information. DPCM method is proposed to the encoding of gray-level information when the subblock can be approximated to be uniform. Also modified quantization method is presented to the encoding of gray-level information when the subblock is not uniform. This technique shows the results of coding 256 level images at the average data rate of about 0.75 bits/pel.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.14-23
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• 1993

This paper proposes an algorithm to reduce the bitrate for transmission of MCP(motion compensated prediction) error signals. Many digital image coders have recently employed hybrid coding schemes which perform motion compensation, DCT transform, quantization, and variable length coding. The variable length coding compresses the quantized DCT coefficient data by removing their statistical redundancy. But some DCT blocks have the interblock statistical redundancy as well as the intrablock one. To utilize both of them, the DCT blocks are classified into the interleaving group and the non-interleaving group. And then each DCT blocks in the interleaving group are is encoded independently, and the DCT blocks in the interleaving group are encoded after interleaving the DCT coefficients. Through the simulations, it is shown that the proposed method outperforms the conventional method in which each DCT block is encoded independently.

• Journal of the military operations research society of Korea
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• v.13 no.1
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• pp.1-18
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• 1987

This paper presents several adaptive linear predictive coding techniques based upon extension of recursive ladder filters. A 2-D recursive ladder filter is extended to a 3-D case which can adaptively track the variation of both spatial and temporal changes of moving images. Using the 2-D/3-D ladder filter and a previous farme predictor, two types of adaptive predictor-control schemes are proposed in which the prediction error at each pel can be obtained at or close to a minimum level. We also investigate several modifications of the basic encoding methods. Performance of the 2-D/3-D ladder filters, their adaptive control schemes, and variations in coding methods are evaluated by computer simulations on a real sequence and compared to the results of motion compensation and frame differential coders. As a validity test of the ladder filters developed, the error signals for the different predictors are compared and evaluated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.1 s.4
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• pp.117-125
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• 2004

Space-time coding and modulation exploit the presence of multiple transmit antennas to improve performance on multipath Rayleigh fading channels. In this paper, we propose the Trellis-Coded Differential Space Time Modulation-OFDM system with multiple symbol detection. The Trellis-code perform the set partition with unitary group codes. The Viterbi decoder containing new branch metrics is introduced in order to improve the bit error rate (BER) in the differential detection of the Unitary differential space time modulation. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.213-216
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• 2001

The H.263 Annex I method for the intraframe coding is based on the prediction in DCT domain, unlike JPEG, MPEG-1, and MPEG-2 where the intraframe coding uses block DCT, independent of the neighboring blocks. In this paper, we show the ineffectiveness of H.263 Annex I prediction method by mathematically deriving the spatial domain meaning of H.263 Annex I prediction method. Based on the derivation, we propose a prediction method which is based on the spatial correlation property of image signals. From the experiment and derivation, we verified the proposed method.

• Structural Engineering and Mechanics
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• v.73 no.1
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• pp.97-108
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• 2020

This study presents a 4 node, 11 DOF/node plate element based on higher order shear deformation theory for lamina composite plates. The theory accounts for parabolic distribution of the transverse shear strain through the thickness of the plate. Differential field equations of composite plates are obtained from energy methods using virtual work principle. Differential field equations of composite plates are obtained from energy methods using virtual work principle. These equations were transformed into the operator form and then transformed into functions with geometric and dynamic boundary conditions with the help of the Gâteaux differential method, after determining that they provide the potential condition. Boundary conditions were determined by performing variational operations. By using the mixed finite element method, plate element named HOPLT44 was developed. After coding in FORTRAN computer program, finite element matrices were transformed into system matrices and various analyzes were performed. The current results are verified with those results obtained in the previous work and the new results are presented in tables and graphs.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.49-55
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• 2016

This paper proposes an adaptive video signal transmission scheme in order to ensure the QoS (Quality of Service) of user requirements. SVC (Scalable Video Coding) is an effective transmission scheme, because that can transmit video signal according to the video layer's weight. However, in previous works, those adaptive transmission systems which are considered about the various channel environments and user requirements have not been insufficiently studied. So, we propose the SVC signal transmission using inter-layer differential OVSF code allocation scheme in MC-CDMA. The proposed scheme is able to obtain each layer signal's protection order and control the sub-block of MC-CDMA by feedback information from receiver. Therefore, our proposed scheme is possible to provide the video quality for each users according to variable channel environments. The simulation results demonstrate the enhancement of proposed system in terms of BER performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.51-59
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• 2017

In this paper, we propose a gray code order of antenna index permutations for differential spatial modulation (DSM). To facilitate the implementation, the well-known Trotter-Johnson ranking and unranking algorithms are adopted, which result in similar computational complexity to the existing DSM that uses the lexicographic order. The signal-to-noise ratio gain achieved by the proposed gray code order over the lexicographic order is also analyzed and verified via simulations. Based on the gray coding framework, we further propose a diversity-enhancing scheme named intersected gray (I-gray) code order, where the permutations of active antenna indices are selected directly from the odd (or even) positions of the full permutations in the gray code order. From analysis and simulations, it is shown that the I-gray code order can harvest an additional transmit diversity order with respect to the gray code order.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.81-89
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• 2009

We propose a D-ATR UWB (Differential-Average Transmitted Reference Ultra Wide Band) system based on impulse radio. The TR-UWB systems including traditional TR (Transmitted Reference) and ATR (Average TR), exhibit a problem of reduced data rate, since reference signals are additionally transmitted. To tackle this issue, the transmitter of the proposed D-ATR system employs a differential coding like the conventional D-TR system. In addition, the receiver of the proposed system has the structure that can improve signal-to-noise ratio of the reference template used in the correlation process, by recursively averaging the received reference signals like the conventional ATR system. The simulation results in the IEEE 802.15.4a UWB multipath channel models reveal that the proposed D-ATR system achieves much better bit error rate performance as compared to the conventional D- TR system.

• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.492-500
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• 2012

In this paper, improved contour region coding method is proposed to accomplish better depth map coding performance. First of all, in order to use correlation between color video and depth map, a structure in SVC is applied to 3DVC. This can reduce bit-rate of the depth map while supporting the video to be transferred via various collection of network. As the depth map is mainly used to synthesize videos from different views, corrupted contour region can damage the overall quality of video. We hereby adapt a new differential quantization method when separating the contour region. The experimental results show that the proposed method can improve video quality by 0.06~0.5dB which translate the bit rate saving by 0.1~1.15%, when compared to the reference software.