• Title/Summary/Keyword: X-means

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Bayesian One-Sided Testing for the Ratio of Poisson Means

  • Kang, Sang-Gil;Kim, Dal-Ho;Lee, Woo-Dong
    • 한국데이터정보과학회:학술대회논문집
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    • 2006.04a
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    • pp.295-306
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    • 2006
  • When X and Y have independent Poisson distributions, we develop a Bayesian one-sided testing procedures for the ratio of two Poisson means. We propose the objective Bayesian one-sided testing procedures for the ratio of two Poisson means based on the fractional Bayes factor and the intrinsic Bayes factor. Some real examples are provided.

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Visualizing Multi-Variable Prediction Functions by Segmented k-CPG's

  • Huh, Myung-Hoe
    • Communications for Statistical Applications and Methods
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    • v.16 no.1
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    • pp.185-193
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    • 2009
  • Machine learning methods such as support vector machines and random forests yield nonparametric prediction functions of the form y = $f(x_1,{\ldots},x_p)$. As a sequel to the previous article (Huh and Lee, 2008) for visualizing nonparametric functions, I propose more sensible graphs for visualizing y = $f(x_1,{\ldots},x_p)$ herein which has two clear advantages over the previous simple graphs. New graphs will show a small number of prototype curves of $f(x_1,{\ldots},x_{j-1},x_j,x_{j+1}{\ldots},x_p)$, revealing statistically plausible portion over the interval of $x_j$ which changes with ($x_1,{\ldots},x_{j-1},x_{j+1},{\ldots},x_p$). To complement the visual display, matching importance measures for each of p predictor variables are produced. The proposed graphs and importance measures are validated in simulated settings and demonstrated for an environmental study.

Hypothesis Testing: Means and Proportions (평균과 비율 비교)

  • Pak, Son-Il;Lee, Young-Won
    • Journal of Veterinary Clinics
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    • v.26 no.5
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    • pp.401-407
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    • 2009
  • In the previous article in this series we introduced the basic concepts for statistical analysis. The present review introduces hypothesis testing for continuous and categorical data for readers of the veterinary science literature. For the analysis of continuous data, we explained t-test to compare a single mean with a hypothesized value and the difference between two means from two independent samples or between two means arising from paired samples. When the data are categorical variables, the $x^2$ test for association and homogeneity, Fisher's exact test and Yates' continuity correction for small samples, and test for trend, in which at least one of the variables is ordinal is described, together with the worked examples. McNemar test for correlated proportions is also discussed. The topics covered may provide a basic understanding of different approaches for analyzing clinical data.

Studies on Purification and Serology of Potato Virus X (감자바이러스 X의 순화와 혈청학적 연구)

  • Lee Soon Hyung;Lee Key Woon;Chung Bong Jo
    • Korean journal of applied entomology
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    • v.16 no.2 s.31
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    • pp.101-104
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    • 1977
  • Potato virus X was purified especially for the preparation of antisera for diagnosis and identification. Potato virus X was isolated Iron infected plants by means of indicator plants and identified in electron microscopy. Isolated PVX was multiplied in tomato plants and purified by a modified procedures. The purity of PVX was 0.59mg/m1. Purified PVX was injected into rabbits once a week for 5 weeks. Antiserum was collected 10 days after the last injection. Produced antiserum was determined 1/1024 titers by means of microprecipitin tests and showed sharp reactions in agar gel-diffusion tests.

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A Learning-Flow Model Supporting Distributed Cognition in IT Education (IT교육에서 분산인지를 지원하는 학습몰입모형)

  • Kim, Sung-Ki;Bae, Ji-Hye
    • Convergence Security Journal
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    • v.12 no.6
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    • pp.51-59
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    • 2012
  • This paper presents a new learning model, "BoX(Battle of X)", which is based on a concept from the culture of B-Boys who enjoy the race of "distributed cognition" to win in their contests. The "battle" means a contest and "X" means a course to which our learning model can be applied. The goal of this paper is to present a learning model that allow students to be in a state of learning-flow and provides them with the ability of creative problem solving simultaneously. The key of the "BoX" implementation is to design a principle that controls contests between students to maximize distributed cognitive activities for reducing individual's cognitive load. This paper also presents how-to of "BoX" implementation and its effects. Through the analysis on learning achievement of students during one year course of IT education, we have confirmed that the "BoX" model provides students with higher learning achievement and learning-flow level in comparison with traditional learning model.

Studies on the Estimation of Leaf Production in Mulberry Trees 1. Estimation of the leaf production by leaf area determination (상엽 수확고 측정에 관한 연구 - 제1보 엽면적에 의한 상엽량의 순서 -)

  • 한경수;장권열;안정준
    • Journal of Sericultural and Entomological Science
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    • v.8
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    • pp.11-25
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    • 1968
  • Various formulae for estimation of leaf production in mulberry trees were investigated and obtained. Four varieties of mulberry trees were used as the materials, and seven characters namely branch length. branch diameter, node number per branch, total branch weight, branch weight except leaves, leaf weight and leaf area, were studied. The formulae to estimate the leaf yield of mulberry trees are as follows: 1. Varietal differences were appeared in means, variances, standard devitations and standard errors of seven characters studied as shown in table 1. 2. Y$_1$=a$_1$X$_1$${\times}$P$_1$......(l) where Y$_1$ means yield per l0a by branch number and leaf weight determination. a$_1$.........leaf weight per branch. X$_1$.......branch number per plant. P$_1$........plant number per l0a. 3. Y$_2$=(a$_2$${\pm}$S. E.${\times}$X$_2$)+P$_1$.......(2) where Y$_2$ means leaf yield per l0a by branch length and leaf weight determination. a$_2$......leaf weight per meter of branch length. S. E. ......standard error. X$_2$....total branch length per plant. P$_1$........plant number per l0a as written above. 4. Y$_3$=(a$_3$${\pm}$S. E${\times}$X$_3$)${\times}$P$_1$.....(3) where Y$_3$ means of yield per l0a by branch diameter measurement. a$_3$.......leaf weight per 1cm of branch diameter. X$_3$......total branch diameter per plant. 5. Y$_4$=(a$_4$${\pm}$S. E.${\times}$X$_4$)P$_1$......(4) where Y$_4$ means leaf yield per 10a by node number determination. a$_4$.......leaf weight per node X$_4$.....total node number per plant. 6. Y$\sub$5/= {(a$\sub$5/${\pm}$S. E.${\times}$X$_2$)Kv}${\times}$P$_1$.......(5) where Y$\sub$5/ means leaf yield per l0a by branch length and leaf area measurement. a$\sub$5/......leaf area per 1 meter of branch length. K$\sub$v/......leaf weight per 100$\textrm{cm}^2$ of leaf area. 7. Y$\sub$6/={(X$_2$$\div$a$\sub$6/${\pm}$S. E.)}${\times}$K$\sub$v/${\times}$P$_1$......(6) where Y$\sub$6/ means leaf yield estimated by leaf area and branch length measurement. a$\sub$6/......branch length per l00$\textrm{cm}^2$ of leaf area. X$_2$, K$\sub$v/ and P$_1$ are written above. 8. Y$\sub$7/= {(a$\sub$7/${\pm}$S. E. ${\times}$X$_3$)}${\times}$K$\sub$v/${\times}$P$_1$.......(7) where Y$\sub$7/ means leaf yield estimates by branch diameter and leaf area measurement. a$\sub$7/......leaf area per lcm of branch diameter. X$_3$, K$\sub$v/ and P$_1$ are written above. 9. Y$\sub$8/= {(X$_3$$\div$a$\sub$8/${\pm}$S. E.)}${\times}$K$\sub$v/${\times}$P$_1$.......(8) where Y$\sub$8/ means leaf yield estimates by leaf area branch diameter. a$\sub$8/......branch diameter per l00$\textrm{cm}^2$ of leaf area. X$_3$, K$\sub$v/, P$_1$ are written above. 10. Y$\sub$9/= {(a$\sub$9/${\pm}$S. E.${\times}$X$_4$)${\times}$K$\sub$v/}${\times}$P$_1$......(9) where Y$\sub$7/ means leaf yield estimates by node number and leaf measurement. a$\sub$9/......leaf area per node of branch. X$_4$, K$\sub$v/, P$_1$ are written above. 11. Y$\sub$10/= {(X$_4$$\div$a$\sub$10/$\div$S. E.)${\times}$K$\sub$v/}${\times}$P$_1$.......(10) where Y$\sub$10/ means leaf yield estimates by leaf area and node number determination. a$\sub$10/.....node number per l00$\textrm{cm}^2$ of leaf area. X$_4$, K$\sub$v/, P$_1$ are written above. Among many estimation methods. estimation method by the branch is the better than the methods by the measurement of node number and branch diameter. Estimation method, by branch length and leaf area determination, by formulae (6), could be the best method to determine the leaf yield of mulberry trees without destroying the leaves and without weighting the leaves of mulberry trees.

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Preparation and Characterization of $Ag/TiO_{2-x}N_x$ Nanoparticles

  • Liu, Z.Q.;Li, Z.H.;Zhou, Y.P.;Ge, C.C.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.436-437
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    • 2006
  • The $Ag/TiO_{2-x}N_x$ nanoparticles were synthesized by photochemical deposition in a $TiO_{2-X}N_X$ suspension system. The prepared products were characterized by means of XRD, Uv-vis and photoluminescence spectra (PL). Its photocatalytic activity was investigated by the decomposition of methylene blue (MB) solution under illumination of visible and ultraviolet light, respectively. Compared to $TiO_{2-x}N_x$, the photocatalytic activity of the as-prepared $Ag/TiO_{2-x}N_x$ is obviously enhanced due to the decreasing recombination of a photoexcitated electron-hole pairs. The Mechanism in which photocatalytic activity is enhanced has been discussed in detail.

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OSCILLATION AND NONOSCILLATION THEOREMS FOR NONLINEAR DIFFERENTIAL EQUATIONS OF SECOND ORDER

  • Kim, Rak-Joong;Kim, Dong-Il
    • Journal of the Korean Mathematical Society
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    • v.44 no.6
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    • pp.1453-1467
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    • 2007
  • By means of a Riccati transform some oscillation or nonoscillation criteria are established for nonlinear differential equations of second order $$(E_1)\;[p(t)|x#(t)|^{\alpha}sgn\;x#(t)]#+q(t)|x(\tau(t)|^{\alpha}sgn\;x(\tau(t))=0$$. $$(E_2),\;(E_3)\;and\;(E_4)\;where\;0<{\alpha}$$ and $${\tau}(t){\leq}t,\;{\tau}#(t)>0,\;{\tau}(t){\rightarrow}{\infty}\;as\;t{\rightarrow}{\infty}$$. In this paper we improve some previous results.

Elastic and Electronic Properties of Point Defects in Titanium Carbide

  • Kang, Dae-Bok
    • Journal of the Korean Chemical Society
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    • v.57 no.6
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    • pp.677-683
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    • 2013
  • A theoretical study of the electronic structures of $TiC_{1-x}$ and $Ti_{1-x}W_xC$ (x = 0, 0.25) is presented. The density of states and crystal orbital overlap population calculations were used to interpret variations of elastic properties induced by carbon vacancies and alloying substitutions. Our results show why the introduction of vacancies into TiC reduces bulk moduli, while W substitution at a Ti site increases the elastic modulus. The effect of the point defects on the bonding in TiC is investigated by means of extended Huckel tight-binding band calculations.