• 한국정보과학회논문지:소프트웨어및응용
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• 제32권12호
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• pp.1260-1270
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• 2005

최근 기계학습 분야에서 커널머신을 이용한 대표적 학습기로 Support Vector Machines (SVM)이 주목 받고 있다. SVM은 통계적 학습이론에 기반하여 뛰어난 일반화 성능을 보여주며, 다양한 패턴인식 문제에 적용되고 있다. 그러나. SVM은 이진 분류기이므로 일반적인 다중 클래스 문제에 곧바로 적용할 수 없다. SVM을 다중 클래스 문제의 하나인 얼굴인식에 도입하기 위한 방법으로는, One-Per-Class와 All-Pairs가 대표적이다. 상기 두 방법은 다중 클래스 문제를 여러 개의 이진 클래스 문제로 분할하고, 이들을 다시 종합하여 최종 결정을 내리는 출력코딩이라는 일반적인 방법에 속한다. 본 논문에서는 이진 분류기인 SVM의 다중 클래스 분류기 확장 방안으로 출력코딩 방법론을 설명한다. 또한 출력코딩 방법론의 대표적인 이론적 기반인 ECOC(Ewor-Correcting Output Codes)를 근간으로 하는 새로운 출력코딩 방법들을 제안하고, 얼굴인식 실험을 통해 SVM을 기반 분류기로 사용할 경우의, 출력코딩 방법의 특성을 비교$\cdot$분석한다.

• 한국멀티미디어학회논문지
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• 제16권7호
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• pp.795-801
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• 2013

서포트 벡터 머신은 뛰어난 일반화 성능에 힘입어 다양한 분야에서 의사 결정 나무나 인공 신경망에 비해 더 좋은 분류 성능을 보이고 있기 때문에 최근 널리 사용되고 있다. 서포트 벡터 머신은 기본적으로 이진 분류 문제를 위하여 설계되었기 때문에 서포트 벡터 머신을 다중 클래스 문제에 적용하기 위한 방법으로 다중 이진 분류기의 출력 결과를 이용하는 출력 코딩 방법이 주로 사용되고 있다. 그러나 출력 코딩 기반 서포트 벡터 머신에 사용된 기존 특징 선택 기법은 각 분류기의 정확도 향상을 위한 특징이 아니라 전체 분류 정확도 향상을 위한 특징을 선택하고 있다. 본 논문에서는 출력 코딩 기반 서포트 벡터 머신의 각 이진 분류기의 분류 정확도를 최대화하는 특징을 각각 선택하여 사용함으로써, 전체 분류 정확도를 향상시키는 특징 선택 기법을 제안한다. 실험 결과는 제안 기법이 기존 특징 선택 기법에 비하여 통계적으로 유의미한 분류 정확도 향상이 있었음을 보여주었다.

• 인터넷정보학회논문지
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• 제21권4호
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• pp.51-57
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• 2020

Currently, High-efficient video coding (HEVC) has become the most promising video coding technology. However, the implementation of HEVC in video streaming systems is restricted by factors such as cost, design complexity, and compatibility with existing systems. While HEVC is considering deploying to various systems with different reached methods, H264/AVC can be one of the best choices for current video streaming systems. This paper presents an adaptive method for manipulating video streams using video coding on an integrated circuit (IC) designed with a private network processor. The proposed system allows to transfer multimedia data from cameras or other video sources to client. For this work, a series of video or audio packages from the video source are forwarded to the designed IC via HDMI cable, called Tx transmitter. The Tx processes input data into a real-time stream using its own protocol according to the Real-Time Transmission Protocol for both video and audio, then Tx transmits output packages to the video client though internet. The client includes hardware or software video/audio decoders to decode the received packages. Tx uses H264/AVC or HEVC video coding to encode video data, and its audio coding is PCM format. By handling the message exchanges between Tx and the client, the transmitted session can be set up quickly. Output results show that transmission's throughput can be achieved about 50 Mbps with approximately 80 msec latency.

• ETRI Journal
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• 제42권3호
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• pp.341-350
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• 2020

In a wireless sensor network (WSN), the data transmission technique based on the cooperative multiple-input multiple-output (CMIMO) scheme reduces the energy consumption of sensor nodes quite effectively by utilizing the space-time block coding scheme. However, in networks with high node density, the scheme is ineffective due to the high degree of correlated data. Therefore, to enhance the energy efficiency in high node density WSNs, we implemented the distributed source coding (DSC) with the virtual multiple-input multiple-output (MIMO) data transmission technique in the WSNs. The DSC-MIMO first compresses redundant source data using the DSC and then sends it to a virtual MIMO link. The results reveal that, in the DSC-MIMO scheme, energy consumption is lower than that in the CMIMO technique; it is also lower in the DSC single-input single-output (SISO) scheme, compared to that in the SISO technique at various code rates, compression rates, and training overhead factors. The results also indicate that the energy consumption per bit is directly proportional to the velocity and training overhead factor in all the energy saving schemes.

• Current Optics and Photonics
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• 제2권5호
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• pp.407-412
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• 2018

An optimal matching approach is proposed to maximally ensure the output power uniformity of the cascaded encoder in the passive optical network (PON) monitoring system based on a remote coding scheme. The calculation results show that the optimum arrangement can effectively reduce the difference of the total insertion loss in comparison to the random arrangement (i.e., 0.07 dB vs 2.67 dB in the cascaded encoder with 16 output ports). The proposed approach realizes the optimum configuration for the $1{\times}2$ optical splitters used without adding any extra components. The test results of the fabricated cascaded encoder with 32 output ports prove the feasibility of the proposed approach.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.984-986
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• 1989

101 coding scheme, one of sliding block coding techniques, provides practically attractive features in some compression applications for image sources such as facsimile. This paper presents a new simple model of 101 coder. The results show that the entropy of the output of the 101 coder can be reduced close to the rate distortion bound of a binary first-order markov source.

• IEIE Transactions on Smart Processing and Computing
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• 제1권3호
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• pp.152-160
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• 2012

This paper proposes a frame-level rate control algorithm for low delay video applications to reduce the fluctuations in the bitrate. The proposed algorithm minimizes the bitrate fluctuations in two ways with minimal coding loss. First, the proposed rate control applies R-Q model to all frames including the first frame of every group of pictures (GOP) except for the first one of a sequence. Conventional rate control algorithms do not use any R-Q models for the first frame of each GOP and do not estimate the generated-bit. An unexpected output rate result from the first frame affects the remainder of the pictures in the rate control. Second, a rate-distortion (R-D) cost is calculated regardless of the hierarchical coding structure for low bitrate fluctuations because the hierarchical coding structure controls the output bitrate in rate distortion optimization (RDO) process. The experimental results show that the average variance of per-frame bits with the proposed algorithm can reduce by approximately 33.8% with a delta peak signal-to-noise ratio (PSNR) degradation of 1.4dB for a "low-delay B" coding structure and by approximately 35.7% with a delta-PSNR degradation of 1.3dB for a "low-delay P" coding structure, compared to HM 8.0 rate control.

• 스마트미디어저널
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• 제1권2호
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• pp.6-11
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• 2012

HEVC 표준에서 변환 계수 부호화 과정은 비트스트림에 포함되는 정보를 직접 부호화하는 핵심 부분으로 변환 계수 주사와 엔트로피 부호화를 포함한다. 최근, JCT-VC(Joint Collaborative Team on Video Coding)는 HEVC 위원회 초안(Committee Draft)을 완성했다. 본 논문에서는 HEVC 표준의 변환 계수 부호화 기술을 설명하고, 화면내 부호기에서의 변환 계수 발생확률을 고려한 효율적인 변환 계수 부호화 기술을 제안한다. 제안하는 방법은 기존 HEVC 변환 계수 부호화 기술에 비해 평균 0.74%의 BD-Rate를 절약한다.

• Journal of Communications and Networks
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• 제12권1호
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• pp.11-18
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• 2010

Diversity-multiplexing tradeoff (DMT) is an efficient tool to measure the performance of multiple-input and multiple-output (MIMO) systems and cooperative systems. Recently, cooperative multicast system with wireless network coding stretched tremendous interesting due to that it can drastically enhance the throughput of the wireless networks. It is desirable to apply DMT to the performance analysis on the multicast system with wireless network coding. In this paper, DMT is performed at the three proposed wireless network coding protocols, i.e., non-regenerative network coding (NRNC), regenerative complex field network coding (RCNC) and regenerative Galois field network coding (RGNC). The DMT analysis shows that under the same system performance, i.e., the same diversity gain, all the three network coding protocols outperform the traditional transmission scheme without network coding in terms of multiplexing gain. Our DMT analysis also exhibits the trends of the three network coding protocols' performance when multiplexing gain is changing from the lower region to the higher region. Monte-Carlo simulations verify the prediction of DMT.

• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.437-447
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• 2006

Error Correcting Output Coding(ECOC) is used to solve multi-class problem. It is known that it improves the classification accuracy. In this paper, we compared various criteria to design code matrix while encoding. In addition. we prorpose an ensemble which uses the ability of each classifier while decoding. We investigate the justification of the proposed method through real data and synthetic data.