• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.21-25
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• 1998

탈황설비 배관내 연소가스의 삼차원 유동장에 대한 전산해석을 수행하였다. 복잡한 형상으로 주어진 배관내의 유동장 특성을 관찰하고 압력손실을 계산하였다. 특히 안개깃의 설치유무에 따른 유동장 특성 변화 및 압력손실 감소효과를 집중적으로 고찰하였다. 안내깃의 설치에 따라 유량배분이 적절하게 되고 압력손실이 현저하게 줄어듬을 알 수 있었다. 배관에서의 압력손실을 계산하여 배관설계 및 송풍기 용량 산정의 적절성을 확인할 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.40-50
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• 2012

In this paper we propose the fast CU (Coding Unit) mode decision method. To reduce computational complexity and save encoding time of HEVC, we divided CU, PU (Prediction Unit) and TU (Transform Unit) decision process into two stages. In the first stage, because $2N{\times}2N$ PU mode is mostly selected among $2N{\times}2N$, $N{\times}2N$, $2N{\times}N$, $N{\times}N$ PU modes, proposed algorithm uses only $2N{\times}2N$ PU mode deciding depth of each CU in the LCU (Largest CU). And then, proposed method decides exact PU and TU modes at the depth level which is decided in the first stage. In addition, early skip decision rule is applied to the proposed method to obtain more efficient computational complexity reduction. The proposed method reduces computational complexity of the HEVC encoder by simplifying a CU depth decision method. We could obtain about 50% computational complexity reduction in comparison with HM 3.3 HEVC reference software while bitrate compressed by the proposed algorithm increases only 2%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7C
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• pp.681-686
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• 2009

In H.264/Ave, an intra prediction added to the P-frame coding slightly improves both of image quality and bit rate, but greatly increases an amount of computation. In order to reduce the increase in computation, this paper proposes an image contents based intra prediction coding using characteristics that the best intra block mode depends on the image content of a macro block. The proposed algorithm estimates the image content with image complexity and the best inter block mode, and then selects or excludes a intra block mode on the basis of it. The simulation results show that the proposed algorithm reduces average O.OldB in image quality, and increases average 0.38% in the bit rate, but reduces average 37.02% in computation time compared with the conventional algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.646-648
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• 1999

본 논문에서는 RSA 암호 알고리즘의 핵심 계산 과정인 모듈로 곱셈 연산의 효율적인 하드웨어 구현을 위해 새로운 알고리즘과 하드웨어 구조를 제시한다. 기존의 몽고메리 알고리즘이 LSB 우선 방법을 사용한 것과는 달리 여기서는 MSB 우선 방법을 사용하였으며, RSA 암호 시스템에서 키가 일정 기간 동안 변하지 않고 유지된다는 점에 착안해 계수(Modulus)에 대한 보수(Complements)를 미리 계산해 놓고 이를 이용하여 모듈로 감소 처리를 간단히 덧셈으로 치환하도록 하였다. 보수들을 저장할 몇 개의 레지스터와 그들 중 하나를 선택하기 위한 간단한 멀티플렉서(Multiplexer)만을 추가함으로써 몽고메리 알고리즘이 안고 있는 홀수 계수 조건과 사후 연산이라는 번거로움을 없앨 수 있다. 본 논문에서 제안하는 알고리즘은 하드웨어 복잡도가 몽고메리 알고리즘과 비슷하며 그 내부 계산 구조를 보여주는 DG(Dependence Graph)의 지역 연결성 (Local Connection), 모듈성(Modularity), 데이터의 규칙적 종속성 (Regular Data Dependency)등으로 인한 실시간 고속 처리를 위한 VLSI 구현에 적합하다.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1069-1072
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• 2011

This paper proposes the method which reduces complexity and improves coding efficiency by solving a problem of HEVC bi-prediction. In current HM 3.0, it is frequently occurred that L0 motion information and L1 motion information are identical in blocks which are bi-predicted. In this case, L1 motion vector is replaced by non-zero motion vector which belongs to first available neighbor block of current block. If they are still identical, prediction mode is replaced by uni-prediction. As an experimental result, in LD(Low-Delay) case, decoding time is reduced roughly 2%~5% and coding gain is roughly 0.3%~0.5% compared with the HM 3.0 anchor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.241-248
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• 2007

In predictive image coding, a LS (Least Squares)-based adaptive predictor is an efficient method to improve image edge predictions. This paper proposes a hybrid interpolation with weighted edge detector. A hybrid approach of switching between bilinear interpolation and EDI (Edge-Directed Interpolation) is proposed in order to reduce the overall computational complexity The objective and subjective quality is also similar to the bilinear interpolation and EDI. Experimental results demonstrate that this hybrid interpolation method that utilizes a weighted edge detector can achieve reduction in complexity with minimal degradation in the interpolation results.

• Journal of Internet Computing and Services
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• v.13 no.2
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• pp.13-20
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• 2012

SLM (Selected Mapping) is an efficient PAPR (Peak-to-Average Power Ratio) reduction scheme without transmitted signal distortion in OFDM (Orthogonal Frequency Division Multiplexing) systems. However, enormous IFFTs (Inverse Fast Fourier Transforms) are needed to generate sufficient candidate OFDM signals, which cause the SLM to become quite complex. In this paper, we propose a new SLM scheme that replaces the IFFT operations with a conversion of the first candidate OFDM signal. The proposed scheme significantly reduces computational complexity, while it shows almost the same PAPR performance as the conventional SLM scheme.

• Journal of Broadcast Engineering
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• v.24 no.3
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• pp.463-471
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• 2019

This paper proposes a method for reducing the complexity of LIC (Local Illuminance Compensation) for bi-directional inter prediction. The LIC performs local illumination compensation using neighboring reconstruction samples of the current block and the reference block to improve the accuracy of the inter prediction. Since the weight and offset required for local illumination compensation are calculated at both sides of the encoder and decoder using the reconstructed samples, there is an advantage that the coding efficiency is improved without signaling any information. Since the weight and the offset are obtained in the encoding prediction step and the decoding step, encoder and decoder complexity are increased. This paper proposes two methods for low complexity LIC. The first method is a method of applying illumination compensation with offset only in bi-directional prediction, and the second is a method of applying LIC after weighted average step of reference block obtained by bidirectional prediction. To evaluate the performance of the proposed method, BD-rate is compared with BMS-2.0.1 using B, C, and D classes of MPEG standard experimental image under RA (Random Access) condition. Experimental results show that the proposed method reduces the average of 0.29%, 0.23%, 0.04% for Y, U, and V in terms of BD-rate performance compared to BMS-2.0.1 and encoding/decoding time is almost same. Although the BD-rate was lost, the calculation complexity of the LIC was greatly reduced as the multiplication operation was removed and the addition operation was halved in the LIC parameter derivation process.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.32-43
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• 2010

This paper presents deblocking filter for low-complexity video decoder. Baseline profile of the H.264/AVC used for mobile devices such as mobile phones has two times higher compression performance than the MPEG-4 Visual but it has a problem of serious complexity as using 1/4-pel interpolation filter, adaptive entropy model and deblocking filter. This paper presents low-complexity deblocking filter for decreasing complexity of decoder with preserving the coding efficiency of the H.264/AVC. In this paper, the proposed low-complexity deblocking filter decreased 49% of branch instruction than conventional approach as calculating value of BS by using the CBP. In addition, a range of filtering of strong filter applied in intra macroblock boundaries was limited to two pixels. According to the experimental results, the proposed low-complexity deblocking filter decreased -0.02% of the BDBitrate comparison with baseline profile of the H.264/AVC, decreased 42% of the complexity of deblocking filter, and decreased 8.96% of the complexity of decoder.

• The Transactions of the Korea Information Processing Society
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• v.5 no.4
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• pp.1048-1056
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• 1998

In this paper, a fractal image coding based on discrete wavelet transform is proposed to improve PSNR at low bit rates and reduce computational complexity of encoding process. The proposed method takes the absolute value of discrete wavelet transform coefficients, and then constructs significant coefficients trees, which indicate the positions and signs of the significant coefficients. This method improves PSNR and reduces computational complexity of mapping contracted domain pool onto range block, by matching only the significant coefficients of range block to coefficients of contracted domain block. Also, this paper proposes a classification scheme which minimizes the number of contracted domain blocks compared with range block. This scheme significantly reduces the number of range and contracted domain block comparison.