• Title/Summary/Keyword: 근사연산

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Almost linear-phase compensator for Cascaded Integrator-Comb filter (Cascaded Integrator-Comb 필터를 위한 근사 선형 위상 보상기)

  • Lee Kyu-Ha;Lee Chung-yong
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.4 s.304
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    • pp.153-158
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    • 2005
  • In this paper, a filter is proposed to compensate droop of the CIC filter for SDR. The proposed compensation filter has almost linear-phase characteristic, requires low operational complexity, and is cost-effective due to its second-order characteristic and lowest operational rate in the baseband.. Especially, it compensates droop in the passband with little performance degradation in the stopband. It is shown, by a design example and its performance analysis, that the proposed compensation method gives performance enhancement in communication systems. It is also shown that the proposed method is superior to conventional ones in view of memory usage and computational load.

Performance Analysis of Error Correction Codes for 3GPP Standard (3GPP 규격 오류 정정 부호 기법의 성능 평가)

  • 신나나;이창우
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.1
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    • pp.81-88
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    • 2004
  • Turbo code has been adopted in the 3GPP standard, since its performance is very close to the Shannon limit. However, the turbo decoder requires a lot of computations and the amount of the memory increases as the block size of turbo codes becomes larger. In order to reduce the complexity of the turbo decoder, the Log-MAP, the Max-Log-MAP and the sliding window algorithm have been proposed. In this paper, the performance of turbo codes adopted in the 3GPP standard is analyzed by using the floating point and the fixed point implementation. The efficient decoding method is also proposed. It is shown that the BER performance of the proposed method is close to that of the Log-MAP algorithm.

Numerical Improvement of Advection Term for Realistic Smoke Simulation (사실적인 연기 시뮬레이션을 위한 이류항 계산의 수치적 개선)

  • Chang, Mun-Hee;Park, Su-Wan;Kim, Eun-Ju;Ryu, Kwan-Woo
    • Proceedings of the Korean Information Science Society Conference
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    • 2006.10a
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    • pp.143-147
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    • 2006
  • 자연 현상에서 나타나는 연기나 난류의 움직임을 사실적으로 시뮬레이션을 할 때 Navier-Stokes 방정식을 이용한다. 이 방정식을 이용한 구현은 방대한 연산량과 계산의 복잡성으로 인하여 실시간 시뮬레이션이 어렵다. 이 때문에 실시간 처리를 위하여 복잡한 수식을 근사화한다. 유체 시뮬레이션의 이류(advect) 과정에서 근사화를 위해 Semi-Lagrangian 방법을 이용할 때, 연기 시뮬레이션은 시간이 지남에 따라 밀도가 현저히 줄어들고 소규모의 소용돌이(small-scale vorticity) 현상이 급격히 감소하는 등의 수치적 소실이 발생한다. 본 논문에서는 이 문제를 해결하기 위해 이류항(advection term)을 계산할 때 새로운 수치적 방법을 제안한다. 본 논문에서는 이류항의 값을 구할 때, 현재 격자 주변의 값 중에서 다음 단계에 현재 격자의 위치로 오는 속도를 가진 격자를 찾아, 그 격자의 속도를 이류 속도 벡터로 활용한다. 이는 밀도와 소용돌이 현상의 수치적 소실을 줄여서 사실성을 높이고 실시간 처리도 가능하게 한다. 또한 본 논문에서는 GPU 구현을 통해 벡터 연산 등의 효율성을 높이며 시뮬레이션의 속도를 향상시킨다.

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Real-Time Motion Blur using Approximated Motion Trails (이동궤적 근사 다면체를 이용한 실시간 모션블러 기법)

  • Hong, MinhPhuoc;Choi, Jinhyung;Oh, Kyoungsu
    • Journal of Korea Game Society
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    • v.17 no.1
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    • pp.17-26
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    • 2017
  • Several algorithms have been introduced to render motion blur in real time by solving the visibility problem in the spatio-temporal domains. However, some algorithms render at interactive frame rates but have artifacts or noise. Therefore, we propose a new algorithm that renders real-time motion blur using extruded triangles. Our method uses two triangles in the previous and the current frame to make an extruded triangle then send it to the rasterization. To solve the occlusion between extruded triangles for a given pixel, we introduce a combining solution using a sorting in front to back order and bitwise operations in the spatio-temporal dimensions.

The Impact of Various Degrees of Composite Minimax ApproximatePolynomials on Convolutional Neural Networks over Fully HomomorphicEncryption (다양한 차수의 합성 미니맥스 근사 다항식이 완전 동형 암호 상에서의 컨볼루션 신경망 네트워크에 미치는 영향)

  • Junghyun Lee;Jong-Seon No
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.33 no.6
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    • pp.861-868
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    • 2023
  • One of the key technologies in providing data analysis in the deep learning while maintaining security is fully homomorphic encryption. Due to constraints in operations on fully homomorphically encrypted data, non-arithmetic functions used in deep learning must be approximated by polynomials. Until now, the degrees of approximation polynomials with composite minimax polynomials have been uniformly set across layers, which poses challenges for effective network designs on fully homomorphic encryption. This study theoretically proves that setting different degrees of approximation polynomials constructed by composite minimax polynomial in each layer does not pose any issues in the inference on convolutional neural networks.

Design of High-Speed 2-D State-Space Digital Filters Based on a Improved Branch-and-Bound Algorithm (개량된 분기한정법에 의한 고속연산 2차원 상태공간 디지털필터의 설계)

  • Lee Young-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.7
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    • pp.1188-1195
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    • 2006
  • This paper presents an efficient design method of 2-D state-space digital filter based on an improved branch-and -bound algorithm. The resultant 2-D state-space digital filters whose coefficients are represented as the sum of two power-of-two terms, are attractive for high-speed operation and simple implementation. The feasibility of the proposed method is demonstrated by several experiments. The results show that the approximation error and group delay characteristic of the resultant filters are similar to those of the digital filters which designed in the continuous coefficient space.

Efficient Parallel Bilateral Filter using GPGPU (GPGPU 를 이용한 양 방향성 필터의 병렬 구현 및 성능 평가)

  • Chang, Ki Joon;Ro, Won Woo
    • Annual Conference of KIPS
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    • 2011.11a
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    • pp.369-372
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    • 2011
  • 양 방향성 필터는 이미지표면 평탄화와 잡음제거에 좋은 성능을 보이지만 특유의 연산 복잡도로 인하여 연산 시간이 오래 걸린다는 단점이 존재한다. 따라서 본 논문에서는 고도의 병렬수행을 바탕으로 하는 그래픽연산장치(GPU)에 적합하도록 수정된 효율적인 양 방향성 필터를 NVIDIA 의 CUDA 를 사용하여 GTX 285 GPU 에서 구현하였다. 영상의 전 영역을 참조하는 대신 인접하고 연속된 영역으로의 근사화, 적은 메모리 사용량, 빠른 접근속도를 가지며 충돌이 최소화된 공유메모리 버퍼, Warp 를 고려한 병합된 메모리 접근방법을 바탕으로 병렬화 하였다. 그 결과, 같은 방식의 순차실행 알고리즘 대비 최소 약 34 배에서 최대 약 76 배의 속도 개선과 30dB 내외의 PSNR 을 갖는 양 방향성 필터를 구현할 수 있었다.

Comparative assessment for Design Oriented Structural Reanalysis Models (설계지향 구조 재해석 모델의 비교 평가)

  • Hwang, Jin Ha;Lee, Jae Seok;Kim, Kyeong Il
    • Journal of Korean Society of Steel Construction
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    • v.12 no.1 s.44
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    • pp.45-54
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    • 2000
  • Design-oriented approximate structural reanalysis models are compared and assessed, particularly with focus on the case of large changes of design variables. The effectiveness and reliability are demonstrated by means of numerical examples. The results of the study suggest the following conclusions relative to the potential of the procedures. (A) local approximation is only appropriate for the case of small changes in design : (B) global approximation is exact for the case of large changes in a small number of design variables, but inefficient : (C) local-global approximation is most effective and reliable for the case of large changes with a large number of design variables. These methods can improve the total efficiency when they are appropriately used to the design information for the redesign process of large scale structures.

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MBO-Tree: A Hierarchical Representation Scheme for Shapes with Natural Approximation and Effective Localization (MBO-Tree: 형상의 자연스러운 근사화와 효과적인 지역화를 지원하는 계층적 표현 방법)

  • 허봉식;김동규;김민환
    • Journal of Korea Multimedia Society
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    • v.5 no.1
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    • pp.18-27
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    • 2002
  • A hierarchical representation scheme for planar curves, MBO-tree, is proposed in this paper, which provides natural approximation and efficient localization. MBO-tree is based on the Douglas-Peucker algorithm (iterative end-point fit algorithm), but approximation errors that are stored with corresponding points in MBO-tree nodes and are used for abstraction measures are adjusted by force to eliminate unnatural approximation. The error adjusting is just making the approximation error of a node in a MBO-tree to be less than or equal to that of its parent. In point of localization, the bounding area of a curve is represented with a minimum bounding octangle (MBO), which can enclose the curve more compactly compared with those of other hierarchical schemes, such as the strip tree, the arc tree and the HAL tree. The MBO satisfies the hierarchical inclusion property that is useful for hierarchical geometrical operations, such as the point-inclusion test and the polygon intersection test. Through several experiments, we found that the proposed scheme was able to approximate more naturally and to localize more effectively.

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An Improved Newton-Raphson's Reciprocal and Inverse Square Root Algorithm (개선된 뉴톤-랍손 역수 및 역제곱근 알고리즘)

  • Cho, Gyeong-Yeon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.1
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    • pp.46-55
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    • 2007
  • The Newton-Raphson's algorithm for finding a floating point reciprocal and inverse square root calculates the result by performing a fixed number of multiplications. In this paper, an improved Newton-Raphson's algorithm is proposed, that performs multiplications a variable number. Since the number of multiplications performed by the proposed algorithm is dependent on the input values, the average number of multiplications per an operation is derived from many reciprocal and inverse square tables with varying sizes. The superiority of this algorithm is proved by comparing this average number with the fixed number of multiplications of the conventional algorithm. Since the proposed algorithm only performs the multiplications until the error gets smaller than a given value, it can be used to improve the performance of a reciprocal and inverse square root unit. Also, it can be used to construct optimized approximate tables. The results of this paper can be applied to many areas that utilize floating point numbers, such as digital signal processing, computer graphics, multimedia, scientific computing, etc.