• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.945-949
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• 2009

This paper proposes an enhanced motion estimation that is one of core parts affecting the coding performance and visual quality in video coding. Although the full search technique, which is the most basic method of the motion estimation, presents the best visual quality, its computational complexity is great, since the search procedures to find the best matched block with each block in the current frame are carried out for all points inside the search area. Thus, various fast algorithms to reduce the computational complexity and maintain good visual quality have been proposed. The PMVFAST adopted the MPEG-4 visual standard produces the visual quality near that by the full search technique with the reduced computational complexity. In this paper, we propose a new motion vector prediction method using median processing. The proposed method reduces the computational complexity for the motion estimation significantly. Experimental results show that the proposed algorithm is faster than the PMVFAST and better than the full search in terms of search speed and average PSNR, respectively.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.107-113
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• 2013

Mobile mobility and data reliability should be guaranteed as well as amounts of data services are essential in the era of smart media. In order to improve the reliability of high-speed data, strong channel coding and modulation techniques are required. In this paper, the structure of Turbo TCM decoder, applying high-order modulation techniques and the DPSAM method which improves performances in time-selective fading channels in the case of burst errors are suggested through the optimal decoding method and iteration decoding so as to improve bandwidth efficiency in Turbo Codes with excellent encoding gain. The proposed method in comparison with the existing method is that 3dB is superior in case that BER is $10^{-2}$ and the number of iterations is 3. In addition, the function is improved at approximately 6dB in case that BER is $10^{-3}$ and the number of iterations is 7. The proposed method requires additional bandwidth; however, the bandwidth loss can be overcome through Turbo TCM technology on the additional bit rate from the bandwidth loss.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.304-313
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• 2021

This paper presents the results of a sea trial for long range underwater acoustic communication conducted in the East Sea in November 2020. Signals were collected through a moving transmitter and 16 vertically arranged receivers, and the range between the transmitter and receiver was about 20 km. The signal in the experiment is a conventional Direct Sequence Spread Spectrum (DSSS) method and a superimposed DSSS method that increases data rate by superimposing of multiple circulated Pseudo Noise (PN) sequences for each symbol. The results show that the uncoded bit error rate averaged over 16 channels to which the channel coding technique was not applied was 0.0005 for the conventional direct sequence spreading method, and was 0.00124 for the superimposed direct sequence spreading method.

• Journal of Broadcast Engineering
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• v.24 no.4
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• pp.660-669
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• 2019

Recently, with the development of three-dimensional scanning devices and multi-dimensional array cameras, research is continuously conducted on techniques for handling three-dimensional data in application fields such as AR (Augmented Reality) / VR (Virtual Reality) and autonomous traveling. In particular, in the AR / VR field, content that expresses 3D video as point data has appeared, but this requires a larger amount of data than conventional 2D images. Therefore, in order to serve 3D point cloud content to users, various technological developments such as highly efficient encoding / decoding and storage, transfer, etc. are required. In this paper, V-PCC bit stream created using V-PCC encoder proposed in MPEG-I (MPEG-Immersive) V-PCC (Video based Point Cloud Compression) group, It is defined by the MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard, and provides to be composed of segments. Also, in order to provide the user with the information of the 3D coordinate system, the depth information parameter of the signaling message is additionally defined. Then, we design a verification platform to verify the technology proposed in this paper, and confirm it in terms of the algorithm of the proposed technology.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.199-205
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• 2018

So many fast motion estimation algorithms for prediction quality and computational reduction have been published due to tremendous computations of full search algorithm. In the paper, we suggest an algorithm that reduces computation effectively, while keeping prediction quality as almost same as that of the full search. The proposed algorithm based on multiple threshold filter calculates the sum of partial block matching error for each candidate, selects the candidates for the next step, compares the stability of optimal candidates with minimum error, removes impossible candidates, and calculates optimal motion vectors by determining the progress of the next step. By doing that, we can find the minimum error point as soon as possible and obtain the better performance of calculation speed by reducing unnecessary computations. The proposed algorithm can be combined with conventional fast motion estimation algorithms as well as by itself, further reduce computation while keeping the prediction quality as almost same as the algorithms, and prove it in the experimental results.

• Journal of Broadcast Engineering
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• v.25 no.6
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• pp.911-921
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• 2020

Recently, MPEG-I (Immersive) has been exploring compression performance through standardization projects for immersive video. The MPEG Immersion Video (MIV) standard technology is intended to provide limited 6DoF based on depth map-based image rendering (DIBR). MIV is a model that processes the Basic View and the residual information into an Additional View, which is a collection of patches. Atlases have the unique characteristics depending on the kind of the view they are included, requiring consideration of the compression efficiency. In this paper, the performance comparison analysis of screen content coding tools such as intra block copy (IBC) is conducted, based on the pattern of various views and patches repetition. It is demonstrated that the proposed method improves coding performance around -15.74% BD-rate reduction in the MIV.

• Journal of Internet Computing and Services
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• v.22 no.3
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• pp.1-8
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• 2021

Ultra high-quality and ultra high-resolution omnidirectional 360-degree video streaming is needed to provide immersive media through head-mounted display(HMD) in virtual reality environment, which requires high bandwidth and computational complexity. One of the approaches avoiding these problems is to apply viewport-dependent selective streaming using tile-based segmentation method. This paper presents a performance analysis of viewport-dependent tiled streaming on 16K ultra high-quality 360-degree videos and 4K 360-degree videos which are widely used. Experimental results showed 42.47% of bjotegaard delta rate(BD-rate) saving on 16K ultra high-quality 360-degree video tiled streaming compared to viewport-independent streaming while 4K 360-degree video showed 26.41% of BD-rate saving. Therefore, this paper verified that tiled streaming is more efficient on ultra-high quality video.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.545-555
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• 2020

This paper presented efficient transceiver structure using sub-band processing for underwater communication in terms of covertness and performance improvement. In aspect of covertness, encrypted coded-bits are divided into groups, and center frequency and sub band are determined by coded-bits of each group. Therefore, as center frequencies are changed randomly, it maintain the covertness effectively. In aspect of performance improvement, the performance of underwater communication mainly depends on multi-path propagation characteristics, Doppler-spread, and frame synchronization. Accordingly, in order to overcome these effects, non-coherent energy detector and turbo equalization method are employed in receiver side. Furthermore, optimal frame synchronization was proposed. Through the simulation and lake experiment, performance analysis was conducted. Especially in the lake experiment, as a result of applying optimal frame synchronization method to receiver structure, errors are corrected in most frames.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.348-358
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• 2022

The purpose of this study is to produce visual content for effective education of Passive verbs and Causative verbs in Korean language education for foreigners. Passive verbs and causative verbs are contents that must be taught to intermediate level learners. However, it is recognized as a difficult item for both learners and Korean teachers because the realization pattern is complicated, and there is no rule to explain the combination relationship between the action and the instruction by suffix. In this article, the use of nonverbal information that can improve the learning effect was considered. Providing verbal and non-verbal information together in language education can be expected to improve learners' communication skills. In particular, visual content is non-verbal information that can positively affect memory enhancement, playback, and transition. Therefore, this study attempted to plan and produce picture cards as visual materials. The picture card, produced with a focus on the correct education of Korean Passive verbs, will efficiently and significantly make Korean Passive verbs and Causative verbs teaching and learning by suffixes.

• Journal of Broadcast Engineering
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• v.26 no.4
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• pp.441-452
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• 2021

In this paper, we propose a method for generating luma signal mapping function to improve the coding efficiency of luma signal mapping methods in LMCS. In this paper, we propose a method to reflect the cognitive and perceptual features by multiplying the attention map of convolutional neural networks on local spatial variance used to reflect local features in the existing LMCS. To evaluate the performance of the proposed method, BD-rate is compared with VTM-12.0 using classes A1, A2, B, C and D of MPEG standard test sequences under AI (All Intra) conditions. As a result of experiments, the proposed method in this paper shows improvement in performance the average of -0.07% for luma components in terms of BD-rate performance compared to VTM-12.0 and encoding/decoding time is almost the same.