• Title/Summary/Keyword: Sum-product

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Updating Sample Variance and Correlation Using Sum of Squares and Sum of Cross product (제곱합과 교차곱합의 특성을 이용한 표본분산과 상관계수의 계산)

  • Cho Tae-Kyoung;Shin Mi-Young
    • The Mathematical Education
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    • v.45 no.3 s.114
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    • pp.315-318
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    • 2006
  • In this paper we present the simple updating formulas for a sum of product and a sum of cross product when a new value is added on or a specific value is eliminated from the original data. The sample variance and correlation for the new data set are derived by new computing formulas. Any statistic which is a function of the sum of product and a sum of cross product also can be updated by proposed method even though the original data is not available.

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Performance and Convergence Analysis of Tree-LDPC codes on the Min-Sum Iterative Decoding Algorithm (Min-Sum 반복 복호 알고리즘을 사용한 Tree-LDPC의 성능과 수렴 분석)

  • Noh Kwang-seok;Heo Jun;Chung Kyuhyuk
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.1C
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    • pp.20-25
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    • 2006
  • In this paper, the performance of Tree-LDPC code is presented based on the min-sum algorithm with scaling and the asymptotic performance in the water fall region is shown by density evolution. We presents that the Tree-LDPC code show a significant performance gain by scaling with the optimal scaling factor which is obtained by density evolution methods. We also show that the performance of min-sum with scaling is as good as the performance of sum-product while the decoding complexity of min-sum algorithm is much lower than that of sum-product algorithm. The Tree-LDPC decoder is implemented on a FPGA chip with a small interleaver size.

FPGA implementation of fuzzy controller using product-sum inference method (Product-sum 추론방식을 이용한 퍼지제어기의 FPGA 구현)

  • 김재희;박준열
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.520-523
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    • 1997
  • This paper presents FPGA implementation of fuzzy controller using Product-Sum inference method. Product-Sum inference method has much better performance than other inference methods. This fuzzy controller is composed of several digital modules, e.g. fuzzifier, rule base, adder, multiplier, select center and divider, and is operated by error and error variation. We synthesized the fuzzy controller and performed wave simulation using Xilinx VHDL tool(ViewLogic, ViewSim).

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Convergence of Min-Sum Decoding of LDPC codes under a Gaussian Approximation (MIN-SUM 복호화 알고리즘을 이용한 LDPC 오류정정부호의 성능분석)

  • Heo, Jun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.10C
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    • pp.936-941
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    • 2003
  • Density evolution was developed as a method for computing the capacity of low-density parity-check(LDPC) codes under the sum-product algorithm [1]. Based on the assumption that the passed messages on the belief propagation model can be approximated well by Gaussian random variables, a modified and simplified version of density evolution technique was introduced in [2]. Recently, the min-sum algorithm was applied to the density evolution of LDPC codes as an alternative decoding algorithm in [3]. Next question is how the min-sum algorithm is combined with a Gaussian approximation. In this paper, the capacity of various rate LDPC codes is obtained using the min-sum algorithm combined with the Gaussian approximation, which gives a simplest way of LDPC code analysis. Unlike the sum-product algorithm, the symmetry condition [4] is not maintained in the min-sum algorithm. Therefore, the variance as well as the mean of Gaussian distribution are recursively computed in this analysis. It is also shown that the min-sum threshold under a gaussian approximation is well matched to the simulation results.

STABILITY OF FUNCTIONAL EQUATIONS ASSOCIATED WITH INNER PRODUCT SPACES: A FIXED POINT APPROACH

  • Park, Choonkil;Hur, Jae Sung;Min, Won June;Nam, Dong Hoon;Roh, Seung Hyeon
    • Korean Journal of Mathematics
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    • v.16 no.3
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    • pp.413-424
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    • 2008
  • In [21], Th.M. Rassias proved that the norm defined over a real vector space V is induced by an inner product if and only if for a fixed integer $n{\geq}2$ $$n{\parallel}\frac{1}{n}\sum\limits_{i=1}^{n}x_i{\parallel}^2+\sum\limits_{i=1}^{n}{\parallel}x_i-\frac{1}{n}\sum\limits_{j=1}^{n}x_j{\parallel}^2=\sum\limits_{i=1}^{n}{\parallel}x_i{\parallel}^2$$ holds for all $x_1,{\dots},x_n{\in}V$. We consider the functional equation $$nf(\frac{1}{n}\sum\limits^n_{i=1}x_i)+\sum\limits_{i=1}^{n}f(x_i-\frac{1}{n}\sum\limits_{j=1}^{n}x_j)=\sum\limits_{i=1}^nf(x_i)$$ Using fixed point methods, we prove the generalized Hyers-Ulam stability of the functional equation $$(1)\;2f(\frac{x+y}{2})+f(\frac{x-y}{2})+f(\frac{y-x}{2})=f(x)+f(y)$$.

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FUNCTIONAL EQUATIONS ASSOCIATED WITH INNER PRODUCT SPACES

  • Park, Choonkil;Huh, Jae Sung;Min, Won June;Nam, Dong Hoon;Roh, Seung Hyeon
    • Journal of the Chungcheong Mathematical Society
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    • v.21 no.4
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    • pp.455-466
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    • 2008
  • In, [7], Th.M. Rassias proved that the norm defined over a real vector space V is induced by an inner product if and only if for a fixed integer $n{\geq}2$ $$n{\left\|{\frac{1}{n}}{\sum\limits_{i=1}^{n}}x_i{\left\|^2+{\sum\limits_{i=1}^{n}}\right\|}{x_i-{\frac{1}{n}}{\sum\limits_{j=1}^{n}x_j}}\right\|^2}={\sum\limits_{i=1}^{n}}{\parallel}x_i{\parallel}^2$$ holds for all $x_1,{\cdots},x_{n}{\in}V$. Let V,W be real vector spaces. It is shown that if a mapping $f:V{\rightarrow}W$ satisfies $$(0.1){\hspace{10}}nf{\left({\frac{1}{n}}{\sum\limits_{i=1}^{n}}x_i \right)}+{\sum\limits_{i=1}^{n}}f{\left({x_i-{\frac{1}{n}}{\sum\limits_{j=1}^{n}}x_i}\right)}\\{\hspace{140}}={\sum\limits_{i=1}^{n}}f(x_i)$$ for all $x_1$, ${\dots}$, $x_{n}{\in}V$ $$(0.2){\hspace{10}}2f\(\frac{x+y}{2}\)+f\(\frac{x-y}{2} \)+f\(\frac{y}{2}-x\)\\{\hspace{185}}=f(x)+f(y)$$ for all $x,y{\in}V$. Furthermore, we prove the generalized Hyers-Ulam stability of the functional equation (0.2) in real Banach spaces.

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New Simplified Sum-Product Algorithm for Low Complexity LDPC Decoding (복잡도를 줄인 LDPC 복호를 위한 새로운 Simplified Sum-Product 알고리즘)

  • Han, Jae-Hee;SunWoo, Myung-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.3C
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    • pp.322-328
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    • 2009
  • This paper proposes new simplified sum-product (SSP) decoding algorithm to improve BER performance for low-density parity-check codes. The proposed SSP algorithm can replace multiplications and divisions with additions and subtractions without extra computations. In addition, the proposed SSP algorithm can simplify both the In[tanh(x)] and tanh-1 [exp(x)] by using two quantization tables which can reduce tremendous computational complexity. Moreover, the simulation results show that the proposed SSP algorithm can improve about $0.3\;{\sim}\;0.8\;dB$ of BER performance compared with the existing modified sum-product algorithms.

A Modified Sum-Product Algorithm for Error Floor Reduction in LDPC Codes (저밀도 패리티 검사부호에서 오류마루 감소를 위한 수정 합-곱 알고리즘)

  • Yu, Seog-Kun;Kang, Seog-Geun;Joo, Eon-Kyeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.5C
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    • pp.423-431
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    • 2010
  • In this paper, a modified sum-product algorithm to correct bit errors captured within the trapping sets, which are produced in decoding of low-density parity-check (LDPC) codes, is proposed. Unlike the original sum-product algorithm, the proposed decoding method consists of two stages. Whether the main cause of decoding failure is the trapping sets or not is determined at the first stage. And the bit errors within the trapping sets are corrected at the second stage. In the modified algorithm, the set of failed check nodes and the transition patterns of hard-decision bits are exploited to search variable nodes in the trapping sets. After inverting information of the variable nodes, the sum-product algorithm is carried out to correct the bit errors. As a result of simulation, the proposed algorithm shows continuously improved error performance with increase in the signal-to-noise ratio. It is, therefore, considered that the modified sum-product algorithm significantly reduces or possibly eliminates the error floor in LDPC codes.

ON DIRECT SUMS IN BOUNDED BCK-ALGEBRAS

  • HUANG YISHENG
    • Communications of the Korean Mathematical Society
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    • v.20 no.2
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    • pp.221-229
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    • 2005
  • In this paper we consider the decompositions of subdirect sums and direct sums in bounded BCK-algebras. The main results are as follows. Given a bounded BCK-algebra X, if X can be decomposed as the subdirect sum $\bar{\bigoplus}_{i{\in}I}A_i$ of a nonzero ideal family $\{A_i\;{\mid}\;i{\in}I\}$ of X, then I is finite, every $A_i$ is bounded, and X is embeddable in the direct sum $\bar{\bigoplus}_{i{\in}I}A_i$ ; if X is with condition (S), then it can be decomposed as the subdirect sum $\bar{\bigoplus}_{i{\in}I}A_i$ if and only if it can be decomposed as the direct sum $\bar{\bigoplus}_{i{\in}I}A_i$ ; if X can be decomposed as the direct sum $\bar{\bigoplus}_{i{\in}I}A_i$, then it is isomorphic to the direct product $\prod_{i{\in}I}A_i$.

QUADRATIC MAPPINGS ASSOCIATED WITH INNER PRODUCT SPACES

  • Lee, Sung Jin
    • Korean Journal of Mathematics
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    • v.19 no.1
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    • pp.77-85
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    • 2011
  • In [7], Th.M. Rassias proved that the norm defined over a real vector space V is induced by an inner product if and only if for a fixed integer $n{\geq}2$ $${\sum_{i=1}^{n}}\left\|x_i-{\frac{1}{n}}{\sum_{j=1}^{n}}x_j \right\|^2={\sum_{i=1}^{n}}{\parallel}x_i{\parallel}^2-n\left\|{\frac{1}{n}}{\sum_{i=1}^{n}}x_i \right\|^2$$ holds for all $x_1$, ${\cdots}$, $x_n{\in}V$. Let V, W be real vector spaces. It is shown that if an even mapping $f:V{\rightarrow}W$ satisfies $$(0.1)\;{\sum_{i=1}^{2n}f}\(x_i-{\frac{1}{2n}}{\sum_{j=1}^{2n}}x_j\)={\sum_{i=1}^{2n}}f(x_i)-2nf\({\frac{1}{2n}}{\sum_{i=1}^{2n}}x_i\)$$ for all $x_1$, ${\cdots}$, $x_{2n}{\in}V$, then the even mapping $f:V{\rightarrow}W$ is quadratic. Furthermore, we prove the generalized Hyers-Ulam stability of the quadratic functional equation (0.1) in Banach spaces.