• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1195-1211
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• 2016

The emerging video coding standard High Efficiency Video Coding (HEVC) has shown almost 40% bit-rate reduction over the state-of-the-art Advanced Video Coding (AVC) standard but at about 40% computational complexity overhead. The main reason for HEVC computational complexity is the inter prediction that accounts for 60%-70% of the whole encoding time. In this paper, we propose several fast coding unit (CU) encoding schemes based on the Merge mode and motion estimation information to reduce the computational complexity caused by the HEVC inter prediction. Firstly, an early Merge mode decision method based on motion estimation (EMD) is proposed for each CU size. Then, a Merge mode based early termination method (MET) is developed to determine the CU size at an early stage. To provide a better balance between computational complexity and coding efficiency, several fast CU encoding schemes are surveyed according to the rate-distortion-complexity characteristics of EMD and MET methods as a function of CU sizes. These fast CU encoding schemes can be seamlessly incorporated in the existing control structures of the HEVC encoder without limiting its potential parallelization and hardware acceleration. Experimental results demonstrate that the proposed schemes achieve 19%-46% computational complexity reduction over the HEVC test model reference software, HM 16.4, at a cost of 0.2%-2.4% bit-rate increases under the random access coding configuration. The respective values under the low-delay B coding configuration are 17%-43% and 0.1%-1.2%.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 1부
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• pp.982-987
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• 2007

The necessity of data compression scheme for volume data has been increased because of the increase of data capacity and the amount of network uses. Now we have various kinds of compression schemes, and we can choose one of them depending on the data types, application fields, the preferences, etc. However, the capacity of data which is produced by application scientists has been excessively increased, and the format of most scientific data is 3D volume. For 2D image or 3D moving pictures, many kinds of standards are established and widely used, but for 3D volume data, specially time-varying volume data, it is very difficult to find any applicable compression schemes. In this paper, we present a compression scheme for encoding time-varying volume data. This scheme is aimed to encoding time-varying volume data for visualization. This scheme uses MPEG's I- and P-frame concept for raising compression ratio. Also, it transforms volume data using Daubechies D4 filter before encoding, so that the image quality is better than other wavelet-based compression schemes. This encoding scheme encodes time-varying volume data composed of single precision floating-point data. In addition, this scheme provides the random reconstruction accessibility for an unit, and can be used for compressing large time-varying volume data using correlation between frames while preserving image qualities.

• ETRI Journal
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• 제37권2호
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• pp.241-250
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• 2015

In this paper, we present novel high-speed transmission schemes for high-speed ultra-high frequency (UHF) radio-frequency identification communication. For high-speed communication, tags communicate with a reader using a high-speed Miller (HS-Miller) encoding and multiple antennas, and a reader communicates with tags using extended pulse-interval encoding (E-PIE). E-PIE can provide up to a two-fold faster data rate than conventional pulse-interval encoding. Using HS-Miller encoding and orthogonal multiplexing techniques, tags can achieve a two- to three-fold faster data rate than Miller encoding without degrading the demodulation performance at a reader. To verify the proposed transmission scheme, the MATLAB/Simulink model for high-speed backscatter based on an HS-Miller modulated subcarrier has been designed and simulated. The simulation results show that the proposed transmission scheme can achieve more than a 3 dB higher BER performance in comparison to a Miller modulated subcarrier.

• ETRI Journal
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• 제34권5호
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• pp.719-726
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• 2012

Messages are generally selected with the same probability in the encoding scheme of rateless codes for equal error protection. In addition, a belief propagation (BP) decoding scheme is generally used because of the low computational complexity. However, the probability of recovering a new message by BP decoding is reduced if both the recovered and unrecovered messages are selected uniformly. Thus, more codeword symbols than expected are required for the perfect recovery of message symbols. Therefore, a new encoding scheme with a nonuniform selection of messages is proposed in this paper. In addition, a BP-Gaussian elimination hybrid decoding scheme that complements the drawback of the BP decoding scheme is proposed. The performances of the proposed schemes are analyzed and compared with those of the conventional schemes.

• 정보관리연구
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• 제36권3호
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• pp.27-49
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• 2005

과학기술정보 서비스를 위한 메타데이터 작업에서 특수문자의 표기법은 항상 중요한 문제였다. 그러므로 본 연구에서는 특수문자의 표기법의 표준화를 위한 방안을 모색하는 작업을 하였다. 이를 위하여, KISTI의 YesKisti에 나타난 특수문자의 다양한 표기사례를 조사하고, 특수문자 표기문제를 표준화의 관점에서 관련된 주요한 현안과 표준동향을 검토하였다. 그런 다음 국내 환경에서, 과학기술정보 특수문자 표기의 표준화를 위한 요건과 과제를 도출하였다.

• Current Optics and Photonics
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• 제3권5호
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• pp.390-400
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• 2019

Encrypted images obtained through double random phase-encoding (DRPE) occupy considerable storage space. We propose efficient compression schemes to reduce the size of the encrypted data. In the proposed schemes, two state-of-art compression methods of JPEG and JP2K are applied to the quantized encrypted phase images obtained by combining the DRPE algorithm with the virtual photon counting imaging technique. We compute the nonlinear cross-correlation between the registered reference images and the compressed input images to verify the performance of the compression of double random phase-encoded images. We show quantitatively through experiments that considerable compression of the encrypted image data can be achieved while security and authentication factors are completely preserved.

• 한국정보과학회논문지:소프트웨어및응용
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• 제34권12호
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• pp.1083-1092
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• 2007

현재 유니코드에서 한글 텍스트의 인코딩 기법은 '완성형 현대한글 음절'과 주로 옛한글을 표현하는데 사용되는 '자모 조합형 한글'로 나뉘고 있다. 그러나 정규화 변환과 유니코드의 한글자모 조합 규정에서 자모와 완성형 현대한글 음절을 다시 조합하여 한글음절로 사용할 수 있게 허용했기 때문에, 구현하는 사람마다 각기 서로 다르게 한글 인코딩을 하고 있다. 이는 인코딩과 정규화 형식을 처음 작성할 당시 옛한글의 확장 사용을 고려하지 않았거나, 한글에 대한 올바른 이해가 부족한 상태에서 작성된 데 따른 결과라 하겠다. 결과적으로 한 개의 한글음절에 대한 여러 가지 표현 방법이 존재함으로써 한글 문자열의 검색, 비교, 정렬에 문제점이 발생한다. 따라서 본 연구에서는 현재 사용되고 있는 한글 인코딩 방법을 중심으로 정규화에 의한 부작용 등의 문제점을 분석하고, 이들을 올바르게 처리하기 위한 효율적인 단일 한글 인코딩 표준 방안을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2913-2929
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• 2014

Traditional vector quantization (VQ) schemes encode image blocks as VQ indices, in which there is significant similarity between the image block and the codeword of the VQ index. Thus, the method can compress an image and maintain good image quality. This paper proposes a novel lossless VQ indices compression algorithm to further compress the VQ index table. Our scheme exploits the high correlation of adjacent image blocks to search for the same VQ index with the current encoding index from the neighboring indices. To increase compression efficiency, codewords in the codebook are sorted according to the degree of similarity of adjacent VQ indices to generate a state codebook to find the same index with the current encoding index. Note that the repetition indices both on the search path and in the state codebooks are excluded to increase the possibility for matching the current encoding index. Experimental results illustrated the superiority of our scheme over other compression schemes in the index domain.

• ETRI Journal
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• 제26권2호
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• pp.122-135
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• 2004

Although frame-based MPEG-4 video services have been successfully deployed since 2000, MPEG-4 video coding is now facing great competition in becoming a dominant player in the market. Object-based coding is one of the key functionalities of MPEG-4 video coding. Real-time object-based video encoding is also important for multimedia broadcasting for the near future. Object-based video services using MPEG-4 have not yet made a successful debut due to several reasons. One of the critical problems is the coding complexity of object-based video coding over frame-based video coding. Since a video object is described with an arbitrary shape, the bitstream contains not only motion and texture data but also shape data. This has introduced additional complexity to the decoder side as well as to the encoder side. In this paper, we have analyzed the current MPEG-4 video encoding tools and proposed efficient coding technologies that reduce the complexity of the encoder. Using the proposed coding schemes, we have obtained a 56 percent reduction in shape-coding complexity over the MPEG-4 video reference software (Microsoft version, 2000 edition).

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1996년도 학술대회
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• pp.147-151
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• 1996

This paper describes two traffic shaping methods for VBR(variable bit rate) video bit streams encoded in the MPEG-2 syntax. Difficulties in control of VBR video traffic are lessened by traffic shaping. Burstness of single layer MPEG-2 video can be reduced by performing intra-refresh in more than one consecutive frames. In two layer encoding of spatial scalability, burstness can be reduced by setting the temporal locations of GOP starting frame of a layer, differently from the other. Queueing analysis shows that these two methods outperform conventional encoding schemes in terms of temporal and semantic QoS requirements.