• 방송공학회논문지
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• 제16권1호
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• pp.123-132
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• 2011

분산 비디오 부호화(Distributed Video Coding: DVC)는 계산 성능 및 전력이 제한된 환경에 적합한 초경량 비디오 부호화 기법으로 주목 받고 있으며, 부호화 성능을 개선하기 위한 많은 연구가 진행되고 있다. 본 논문에서는 DVC의 부호화 성능 개선을 위한 율-왜곡(Rate-Distortion) 기반의 영역별 선택적 블록 부호화 기법을 제안한다. 제안 기법은 복호기에서 보조정보를 얻는 과정에서 얻어지는 움직임 벡터가 부호기로 피드백 되는 경우, 이를 이용하여 움직임 보상 예측 신호를 구하고 율-왜곡 기반으로 블록 단위로 선택적 블록 부호화를 수행한다. 모의실험을 통하여 본 논문에서 제안한 움직임 정보 피드백을 이용한 율-왜곡 기반의 선택적 블록 부호화 기법이 기존의 DVC 부호화 기법에 비해 시퀀스에 따라 최대 약 2.2 dB의 PSNR 성능 향상을 확인하였다. 또한 율-왜곡을 고려하여 일부 영역만 부호화함으로써 기존 방식에 비해 부호화 복잡도를 줄일 수 있음을 보인다.

• 방송공학회논문지
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• 제15권5호
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• pp.642-652
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• 2010

분산 비디오 부호화 기법(DVC: Distributed Video Coding)은 다양한 응용에서 낮은 복잡도의 영상 부호화를 가능하게 하는 미래기술의 한 가지로써 많은 연구의 대상이 되고 있다. 그러나 분산 비디오 부호화 기법의 성능은 연산량의 제한으로 인하여 지그-재그주사, 줄 길이 부호, 엔트로피 부호 그리고 스킵 매크로블록을 사용하는 기존의 국제 동영상 압축 부호화 기법에 비해 우수하지 못한 한계점이 있다. 이러한 한계점을 극복하기 위해, 본 논문에서는 먼저 복호화기 측에서 보조정보를 얻는 과정에서 블록별 예측 왜곡을 구하고, 예측 왜곡이 큰 블록에 대해서는 움직임 정보를 피드백시켜 부호화기로 하여금 움직임 보상 프레임 차 신호를 구하여 선택적으로 부호화하는 방식을 제안한다. 모의실험을 통하여 본 논문에서 제안한 부호화 기법은 기존의 화면 간 부호화 방식들에 근접하는 뛰어난 부호화 성능을 얻을 수 있음을 보인다.

• Journal of Information Processing Systems
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• 제16권4호
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• pp.820-831
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• 2020

Extractive document summarization aims to select a few sentences while preserving its main information on a given document, but the current extractive methods do not consider the sentence-information repeat problem especially for news document summarization. In view of the importance and redundancy of news text information, in this paper, we propose a neural extractive summarization approach with joint sentence semantic clipping and selection, which can effectively solve the problem of news text summary sentence repetition. Specifically, a hierarchical selective encoding network is constructed for both sentence-level and document-level document representations, and data containing important information is extracted on news text; a sentence extractor strategy is then adopted for joint scoring and redundant information clipping. This way, our model strikes a balance between important information extraction and redundant information filtering. Experimental results on both CNN/Daily Mail dataset and Court Public Opinion News dataset we built are presented to show the effectiveness of our proposed approach in terms of ROUGE metrics, especially for redundant information filtering.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.397-400
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• 2002

In this paper, a novel noncoherent multiuser detector with diversity reception for a differentially encoded DS/CDMA signal in a frequency-selective Rayleigh fading channel is proposed. The proposed receiver employs multipath decorrelator and decision feedback differential detector (DFDD) with diversity reception. DFDD performs differential encoding and diversity combining. The performance is obtained by analysis and simulation and it is sown that the proposed receiver outperforms conventional differential receiver with slight increase of complexity.

• 로봇학회논문지
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• 제8권1호
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• pp.1-7
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• 2013

Body gesture Recognition has been one of the interested research field for Human-Robot Interaction(HRI). Most of the conventional body gesture recognition algorithms used Hidden Markov Model(HMM) for modeling gestures which have spatio-temporal variabilities. However, HMM-based algorithms have difficulties excluding meaningless gestures. Besides, it is necessary for conventional body gesture recognition algorithms to perform gesture segmentation first, then sends the extracted gesture to the HMM for gesture recognition. This separated system causes time delay between two continuing gestures to be recognized, and it makes the system inappropriate for continuous gesture recognition. To overcome these two limitations, this paper suggests primitive body model encoding, which performs spatio/temporal quantization of motions from human body model and encodes them into predefined primitive codes for each link of a body model, and Selective/Asynchronous Input-Parallel State machine(SAI-PSM) for multiple-simultaneous gesture recognition. The experimental results showed that the proposed gesture recognition system using primitive body model encoding and SAI-PSM can exclude meaningless gestures well from the continuous body model data, while performing multiple-simultaneous gesture recognition without losing recognition rates compared to the previous HMM-based work.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4275-4291
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• 2021

With the unprecedented growth of textual information on the Internet, an efficient automatic summarization system has become an urgent need. Recently, the neural network models based on the encoder-decoder with an attention mechanism have demonstrated powerful capabilities in the sentence summarization task. However, for paragraphs or longer document summarization, these models fail to mine the core information in the input text, which leads to information loss and repetitions. In this paper, we propose an abstractive document summarization method by applying guidance signals of key sentences to the encoder based on the hierarchical encoder-decoder architecture, denoted as KI-HABS. Specifically, we first train an extractor to extract key sentences in the input document by the hierarchical bidirectional GRU. Then, we encode the key sentences to the key information representation in the sentence level. Finally, we adopt key information representation guided selective encoding strategies to filter source information, which establishes a connection between the key sentences and the document. We use the CNN/Daily Mail and Gigaword datasets to evaluate our model. The experimental results demonstrate that our method generates more informative and concise summaries, achieving better performance than the competitive models.

• 한국통신학회논문지
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• 제25권10A호
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• pp.1473-1479
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• 2000

This paper presents the performance evaluation of an adaptive QAM scheme under flat and frequency selective fading channels for indoor wireless communication systems. The QAM modulation is combined with differential encoding and the demodulation process is carried out noncoherently. The adaptation is performed by varying the modulation level of QAM, depending upon received signal strength. The adaptation mechanism allows a 2- or 3-bit increase or decrease at a time, if the channel condition is considered to be significantly good or bad. Simulation results show that the average number of bits per symbol (ABPS) for each symbol block transmitted over a flat fading channel is higher than 5.0 and the BER performance is better than 10^-4 for a SNR value higher than 30 dB. For frequency selective fading channels, an oversampling technique in the receiver was employed. The BER performance obtained for frequency selective fading channels is better than 10^-4 with a SNR value of 40 dB and ABPS is found to be approximately 5.5. Therefore, this scheme is very useful in that it provides both very high bandwidth efficiency and acceptable performance with moderate SNR values over flat and frequency selective fading channels. In addition, this scheme provides reduced receiver complexity by way of noncoherent detection.

• 전기전자학회논문지
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• 제22권4호
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• pp.1163-1167
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• 2018

비트 값의 반전을 이용하여 정규 허프만 코드의 선택적인 암호화 방법을 제안하였다. 심벌들을 일정한 크기의 블록으로 나누어 블록안의 각 심벌들을 정규 허프만 코딩으로 압축한다. 블록별로 원 코드로 보낼 것인지 암호화하여 보낼것인지 결정하고 암호화 블록은 전제 비트들의 값을 반전시키고 암호화하지 않는 블록들은 원 코딩 데이터를 암호화 정보와 함께 전송한다. 수신측에서 압축된 데이터를 암호화 정보를 이용하여 해독가능하다.

• 방송공학회논문지
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• 제11권3호
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• pp.326-335
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• 2006

본 논문에서는 직교 주파수분할다중화(orthogonal frequency division multiplexing; OFDM)의 변조된 신호열에서 항상 최소화된 첨두전력 대 평균전력비(peak-to-average power ratio; PAPR)를 보장할 수 있는 블록부호가 제안된다. 제안된 최소 PAPR 부호(minimum PAPR code; MPC) 부호화 과정은 씨앗부호어(seed codeword) 검색, 레지스터 요소의 순회천이(circular shifting), 그리고 비트반전(bit inversion)으로 이루어진다. 시간영역 전송신호열의 첨두 포락선전력(peak envelope power; PEP)이 레지스터에 저장된 부호어의 순회천이와 부호의 비트반전에 대하여 변화되지 않음을 보였다. 이러한 성질에 기반하여 체계적인 MPC 부호화 규칙이 제안되었다. 제안된 부호 규칙으로 MPC 부호화를 위한 조견표(look-up table)의 크기를 대폭 감소시킬 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2056-2059
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• 2003

The rate control is very important to solve the difficulties arising from bit-rate on transmission through channel and to improve video quality. It is very important to point out that the amount of output bit obtained the encoding process using rate controller brings many problems on the transmission of channels and furthermore output bitstream decoded affects directly on the visual quality of displayed subject. In this paper, the effective rate control algorithm by rate-distortion modeling using MPEG-4 encoder is proposed. The proposed rate control has applied different weighting by VOP prediction type and even in the same VOP prediction type, the predicted reference allocates more bit. Through these bit allocation the minimization of distortion can be achieved preventing propagation of quantization error The amount of saved bitstream obtained by the proposed algorithm in this thesis is allocated to I-VOP using region of interest(ROI) selective enhancement on the next GOV encoding process and this process brought the improvement of visual quality.