• Title/Summary/Keyword: symmetric J measure

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Utilizing Purely Symmetric J Measure for Association Rules (연관성 규칙의 탐색을 위한 순수 대칭적 J 측도의 활용)

  • Park, Hee-Chang
    • Journal of the Korean Data Analysis Society
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    • v.20 no.6
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    • pp.2865-2872
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    • 2018
  • In the field of data mining technique, there are various methods such as association rules, cluster analysis, decision tree, neural network. Among them, association rules are defined by using various association evaluation criteria such as support, confidence, and lift. Agrawal et al. (1993) first proposed this association rule, and since then research has been conducted by many scholars. Recently, studies related to crossover entropy have been published (Park, 2016b). In this paper, we proposed a purely symmetric J measure considering directionality and purity in the previously published J measure, and examined its usefulness by using examples. As a result, it is found that the pure symmetric J measure changes more clearly than the conventional J measure, the symmetric J measure, and the pure crossover entropy measure as the frequency of coincidence increases. The variation of the pure symmetric J measure was also larger depending on the magnitude of the inconsistency, and the presence or absence of the association was more clearly understood.

TWO-SIDED ESTIMATES FOR TRANSITION PROBABILITIES OF SYMMETRIC MARKOV CHAINS ON ℤd

  • Zhi-He Chen
    • Journal of the Korean Mathematical Society
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    • v.60 no.3
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    • pp.537-564
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    • 2023
  • In this paper, we are mainly concerned with two-sided estimates for transition probabilities of symmetric Markov chains on ℤd, whose one-step transition probability is comparable to |x - y|-dϕj (|x - y|)-1 with ϕj being a positive regularly varying function on [1, ∞) with index α ∈ [2, ∞). For upper bounds, we directly apply the comparison idea and the Davies method, which considerably improves the existing arguments in the literature; while for lower bounds the relation with the corresponding continuous time symmetric Markov chains are fully used. In particular, our results answer one open question mentioned in the paper by Murugan and Saloff-Coste (2015).

A Note on the Frequency and Normal Mode Equations of Uniform Timoshenko Beams (균일단면(均一斷面) Timoshenko보의 진동수방정식(振動數方程式) 및 기준함수(基準函數)에 관하여)

  • K.C.,Kim;Y.J.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.19 no.2
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    • pp.27-31
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    • 1982
  • The practical utilization of the frequency and normal mode equations of uniform Timoshenko beams such as those presented by Huang is not simple due to their highly trancendental nature. In this note largely simplified equations obtained for the fixed-fixed and the free-free boundary conditions, the modes of which are separable into symmetric modes and antisymmetric ones, are given. Numerical results obtains for six common-type boundary conditions show that the quantitative measure of the effect of rotary inertia and shear deformation on the natural frequency is greatly dependent upon the boundary conditions as well as the order number.

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Turbulent Flow Field on Boundary Layer Flow Conditions in the Near-Wake of a Flat Plate (평판 근접 후류에서 경계층의 유동조건에 따른 난류유동장)

  • Kim, D.H.;Chang, J.W.
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.12 no.3
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    • pp.25-39
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    • 2004
  • An experimental study was quantitatively carried out in order to investigate the influence of flow conditions on a boundary layer in the near-wake of a flat plate. Tripping wires attached at various positions were selected to change flow conditions of a boundary layer in the vicinity of trailing edge. The flows such as laminar, transitional, and turbulent boundary layer at 0.98C from the leading edge are imposed to investigate the evolution of symmetric and asymmetric wake. Measurements were made at freestream velocity of 6.0m/s, and the corresponding Reynolds number is $2.8{\times}10^5$. An x-type hot-wire probe(55P61) was employed to measure at 8 stations in the near-wake region. Test results show that the near-wake of the flat plate for the case of a laminar and transitional boundary layer is sensitive to mean flow shear generated after separation but for the case of turbulent boundary layer is insensitive.

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