• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.67-80
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• 2017

This paper presents a hole-filling method using extrapolated spatio-temporal background information to obtain a synthesized view. A new temporal background model using non-overlapped patch based background codebook is introduced to extrapolate temporal background information In addition, a depth-map driven spatial local background estimation is addressed to define spatial background constraints that represent the lower and upper bounds of a background candidate. Background holes are filled by comparing the similarities between the temporal background information and the spatial background constraints. Additionally, a depth map-based ghost removal filter is described to solve the problem of the non-fit between a color image and the corresponding depth map of a virtual view after 3-D warping. Finally, an inpainting is applied to fill in the remaining holes with the priority function that includes a new depth term. The experimental results demonstrated that the proposed method led to results that promised subjective and objective improvement over the state-of-the-art methods.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.563-572
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• 2020

Tidal flats provide important indicators that inform the condition of the environment, so we need to monitor them systematically. Currently, the projects to monitor tidal flats by periodically observing the creatures in tidal flats are underway. Still, it is done in a way that people observe directly, so it is not systematic and efficient. In this paper, we propose a background modeling method for tidal flat images that can be applied to a system that automatically monitors creatures living in tidal flats using sensor network technology. The application of sensor network technology makes it difficult to collect enough images due to the limitation of transmission capacity. Therefore, in this paper, we propose a method to effectively model the background and generate foreground maps by reflecting the characteristics of tidal flat images in the situation where the number of images to be used for analysis is small. Experimental results show that the proposed method models the background of a tidal flat image easily and accurately.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2391-2400
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• 1999

Vector quantizer (VQ) is an efficient data compression technique for low bit rate applications. However, the major disadvantage of VQ is its encoding complexity which increases dramatically as the vector dimension and bit rate increase. Even though one can use a modified VQ to reduce the encoding complexity, it is nearly impossible to implement such a VQ at a high bit rate or for a large vector dimension because of the enormously large memory requirement for the codebook and the very large training sequence (TS) size. To overcome this difficulty, in this paper we propose a novel structurally constrained VQ for the high bit rate and the large vector dimension cases in order to obtain VQ-level performance. Furthermore, this VQ can be extended to the low bit rate applications. The proposed quantization scheme has a form of feed-forward adaptive quantizer with a short adaptation period. Hence, we call this quantization scheme sample-adaptive product quantizer (SAPQ). SAPQ can provide a 2 ~3dB improvement over the Lloyd-Max scalar quantizers.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1307-1316
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• 1996

In this paper, we propose a vector quantization method which uses a dynamic address mapping based on exploring the high interblock correlation. In the proposed method, we reduce bit-rate by defining an address transform function, which maps a VQ address of an input block which will be encoded into a new address in the reordered codebook by using side match error. In one case that an original address can be transformed into a new transformed address which is lower than the threshold value, we encode the new address of the transformed convector, and in the other case we encode the address of the original convector which is not transformed. Experimental results indicate that the proposed scheme reduces the bit-rate by 45~50% compared with the ordi-nary VQ method forimage compression, at the same quality of the reconstructed image as that of the ordinary VQ system.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.26-33
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• 2014

For wireless communication systems of (and beyond) LTE-Advanced, multiple-input multiple-output (MIMO) with an increased number of antennas will be utilized for system throughput improvement. When using such an increased number of antenna, an excessive amount of overhead in channel state information (CSI) feedback can be a serious problem. In this paper, we propose methods which reduce the CSI feedback overhead, particularly including application strategies for multi-rank transmission targeted for two or more reception antennas. To reduce the information which is instantaneously transmitted from the reception node to the transmission node, we present a beamforming method utilizing singular value decomposition (SVD) based on channel estimation of partitioned antenna arrays. Since the SVDs for partial matrices of the channel may lose the characteristics of the original unpartitioned matrix, we explain an appropriate scheme to cope with this problem.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.3
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• pp.13-20
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• 1990

This paper describes an interframe image coding using motion compensated and classified vector quantizer (MC-CVQ). It is essential to carefully encode blocks with significant pels in motion compensated vector quantizers (MCVQ). In this respect, we propose a new CVQ algorithm which is appropriate to the coding of interframe prediction error after motion compensation. In order to encode an image efficiently at a low bit rate, we partition each block, which is the processing element in MC, into equally sized 4 vectors, and classify vectors into 15 classes according to the position of significant pels. Vectors in each class are then encoded by the vector quantizer with the codebook independently designed for the class. The computer simulation shows that the signal-to-noise ratio and the average bit rate of MC-CVQ are 35-37dB and 0.2-0.25bit/pel, respectively, for the videophone or video conference type image.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.127-136
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• 1998

This paper proposes a new MVQMultistage Vector Quantizer) using a hybrid structure. While in a conventional MVQ, the quantizers of all stages perform the encoding procedure for input signals, we introduce a quantizer that performs selectively. The proposed quantizer with a hybrid structure is composed of a FSVQ(Finite-State Vector Quantizer) for the first stage and a ordinary VQ(Vector Quantizer) for the second stage. A input block is firstly encoded by the FSVQ of the first stage. If the Euclidean distortion measure between original signals and the codevector selected from the state codebook of the FSVQ is less than a prespecified value, only the FSVQ is used for image coding. Otherwise, both the FSVQ of the first stage and the ordinary VQ of the second stage are used for image coding. While the conventional MVQ has an advantage that can achieve low encoding complexity in comparison to the ordinary VQ, but has a disadvantage that is suboptimal with respect to the performance measure and can not achieve the bit rate reduction, the proposed method achieve not only the bit rate reduction but also the performance improvement.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.3
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• pp.14-26
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• 2012

In this paper, a fast diagonal-weighted Jacket matrices (DWJMs) is proposed to have the orthogonal architecture. We develop the successive DWJM to reduce the computational load while factorizing the large-order DWJMs into the low-order sparse matrices with the fast algorithms. The proposed DWJM is then applied to the precoding multiple-input and multiple output (MIMO) wireless communications because of its diagonal-weighted framework with element-wise inverse characteristics. Based on the properties of the DWJM, the DWJM can be used as alternative open loop cyclic delay diversity (CDD) precoding, which has recently become part of the cellular communications systems. Performance of the DWJM-based precoding system is verified for orthogonal space-time block code (OSTBC) MIMO LTE systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.11-18
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• 2012

In this paper, we propose a novel equal-gain differential precoding scheme utilizing temporal correlation of channels. The conventional differential precoding schemes only quantize a part of channel space not the whole channel space, so that it virtually increases codebook size which enhances the system capacity. But the conventional differential schemes increase peak-to-average power ratio (PAPR) without preserving equal-gain transmission. This paper proposes the design method of equal-gain differential precoding scheme and analyzes the performances of the proposed equal-gain precoding scheme. Monte-Carlo simulations verify that the proposed scheme has an advantage of 1dB to obtain the same system capacity with the same amount of feedback information compared with the conventional LTE schemes, with showing very low PAPR property.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.78-83
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• 2000

Vocoders used in digital mobile phone adopt new improved algorithm to achieve better communication quality. Therefore the communication problem occurs between mobile phones using different vocoder algorithms. In this paper, the efficient implementation of 8kbps and 13kbps QCELP into one DSP chip to solve this problem is presented. We also describe the optimization method at each level, that is, algorithm-level, equation-level, and coding-level, to reduce the complexity for the QCELP vocoder algorithm implementation. The complexity in the codebook search-loop that is the main part for the QCELP algorithm complexity can be reduced about 50% by using these optimizations. The QCELP implementation with our DSP requires only 25 MIPS of computation for the 8kbps and 33 MIPS for the 13kbps ones. The DSP for our real-time implementation is a 16-bit fixed-point one specifically designed for vocoder applications and has a simple architecture compared to general-purpose ones in order to reduce the power consumption.