• Title/Summary/Keyword: prime number

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Floristic Study of Gageodo in Korea (가거도의 관속식물상)

  • Yang, Sun-Gyu;Jang, Chang-Seok;Jang, Hyun-Do;Lee, Ro-Young;Park, Min-Su;Kim, Ki-Hong;Oh, Byoung-Un
    • Korean Journal of Plant Resources
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    • v.26 no.5
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    • pp.597-612
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    • 2013
  • The flora of Is. Gageodo (N $34^{\circ}02^{\prime}{\sim}34^{\circ}05^{\prime}$, E $125^{\circ}05^{\prime}{\sim}125^{\circ}08^{\prime}$) in Sinangun (Province Jeollanamdo) was surveyed from April 2010 to October 2011. The vascular plants from the results of 23 field surveys were revealed as 385 taxa; in total 98 families, 258 genera, 348 species, three subspecies, 31 varieties and four forms. Fifty taxa were the first records in this region. The plants in various categories were discovered in this study. The number of Korean endemic plants were 7 taxa, and 8 taxa designated by Korean Forest Service as rare plants were investigated in this region. The plants above the third degree among the floristic regional indicator plants designated by Korean Ministry of Environment were 30 taxa. In addition, 28 taxa of the naturalized plants were recorded.

A Polynomial Time Algorithm for Edge Coloring Problem (간선 색칠 문제의 다항시간 알고리즘)

  • Lee, Sang-Un
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.11
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    • pp.159-165
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    • 2013
  • This paper proposes a O(E) polynomial-time algorithm that has been devised to simultaneously solve edge-coloring problem and graph classification problem both of which remain NP-complete. The proposed algorithm selects an edge connecting maximum and minimum degree vertices so as to determine the number of edge coloring ${\chi}^{\prime}(G)$. Determined ${\chi}^{\prime}(G)$ is in turn either ${\Delta}(G)$ or ${\Delta}(G)+1$. Eventually, the result could be classified as class 1 if ${\chi}^{\prime}(G)={\Delta}(G)$ and as category 2 if ${\chi}^{\prime}(G)={\Delta}(G)+1$. This paper also proves Vizing's planar graph conjecture, which states that 'all simple, planar graphs with maximum degree six or seven are of class one, closing the remaining possible case', which has known to be NP-complete.

An Efficient Updates Processing Using Labeling Scheme In Dynamic Ordered XML Trees (동적 순서 XML 트리에서 레이블링 기법을 이용한 효율적인 수정처리)

  • Lee, Kang-Woo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.12
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    • pp.2219-2225
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    • 2008
  • Labeling schemes which don't consider about frequent update in dynamic XML documents need relabeling process to reflect the changed label information whenever the tree of XML document is update. There is disadvantage of considerable expenses in the dynamic XML document which can occurs frequent update. To solve this problem, we suggest prime number labeling scheme that doesn't need relabeling process. However the prime number labeling scheme does not consider that it needs to update the sibling order of nodes in the XML tree of document. This update process needs much costs because the most of the XML tree of document has to be relabeling and recalculation. In this paper, we propose the prime number labeling scheme with sibling order value that can maintain the sibling order without relabeling or recalculation the XML tree of documents.

Wavelength-Time Codes using Modified Time Mapped Prime Sequences for Optical CDMA (변형된 Time Mapped Prime Sequence를 이용한 Wavelength-Time Code for Optical CDMA)

  • Jhee, Yoon-Kyoo
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.10
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    • pp.29-33
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    • 2010
  • In this paper, a new family of wavelength-time codewords using modified time mapped prime sequences as a time spreading pattern is constructed. When $P_t$ = 3, we can construct $P_w^2$ wavelength-time codewords with low autocorrelation sidelobe and crosscorrelation of less than or equal to 1. When $P_t$ = 5 and $P_t$ = 7, the number of wavelength-time codewords of $P_w^2$ can be constructed with good crosscorrelation of 1 and autocorrelation of less than or equal to 2.

SYMMETRIC BI-DERIVATIONS IN PRIME RINGS

  • Jung, Yong-Soo
    • Journal of applied mathematics & informatics
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    • v.5 no.3
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    • pp.819-826
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    • 1998
  • The purpose of this paper is to prove the following results; (1) Let R be a prime ring of char $(R)\neq 2$ and I a nonzero left ideal of R. The existence of a nonzero symmetric bi-derivation D : $R\timesR\;\longrightarrow\;$ such that d is sew-commuting on I where d is the trace of D forces R to be commutative (2) Let m and n be integers with $m\;\neq\;0.\;or\;n\neq\;0$. Let R be a noncommutative prime ring of char$ (R))\neq \; 2-1\; p_1 \;n_1$ where p is a prime number which is a divisor of m, and I a nonzero two-sided ideal of R. Let $D_1$ ; $R\;\times\;R\;\longrightarrow\;and\;$ $D_2\;:\;R\;\times\;R\;longrightarrow\;R$ be symmetric bi-derivations. Suppose further that there exists a symmetric bi-additive mapping B ; $R\;\times\;R\;\longrightarrow\;and\;$ such that $md_1(\chi)\chi + n\chi d_2(\chi)=f(\chi$) holds for all $\chi$$\in$I, where $d_1 \;and\; d_2$ are the traces of $D_1 \;and\; D_2$ respectively and f is the trace of B. Then we have $D_1=0 \;and\; D_2=0$.

Plasma Electrolytic Oxidation of Ti-25Ta-xHf for Dental Implants (치과임플란트용 Ti-25Ta-xHf 합금의 플라즈마 전해 산화)

  • Kim, Jeong-Jae;Choe, Han-Cheol
    • Journal of the Korean institute of surface engineering
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    • v.51 no.6
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    • pp.344-353
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    • 2018
  • Plasma electrolytic oxidation of Ti-25Ta-xHf alloy in electrolyte containing Ca and P for dental implants was investigated using various experimental techniques. Ti-25Ta-xHf (x=0 and 15 wt.%) alloys were manufactured in an arc-melting vacuum furnace. Micropores were formed in PEO films on Ti-25Ta-xHf alloys in 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at 240 V, 270 V and 300 V for 3 min, respectively. The microstructure of Ti-25Ta-xHf alloys changed from (${\alpha}^{\prime}+{\alpha}^{{\prime}{\prime}}$) phase to (${\alpha}^{{\prime}{\prime}}+{\beta}$) phase by addition of Hf. As the applied potential increased, the number of pore and the area ratio of occupied by micro-pore decreased, whereas the pore size increased. The anatase phase increase as the applied potential increased. Also, the crystallite size of anatase-$TiO_2$ can be controlled by applied voltage.

Effects of Reynolds Number and Shape of Manifold on Flow Rate in Separator for Polymer Electrolyte Fuel Cell (ICCAS 2004)

  • Huang, Chaii;Ozawa, Yoshikuni;Ennoji, Hisayuki;Iijima, Toshio
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.68-71
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    • 2004
  • Recently, a great deal of research and development of a fuel cell have been carried out to solve problems on the drain of fossil fuel, air pollution and global warning. In order to improve the efficiency of a fuel cell, it is necessary to clarify the flow in separator. In this study, distributions of velocity flow rate and pressure, and streamlines are examined in detail from numerical analysis with CFD code. In the experiment the distribution of flow rate is measured and flow in the each grooves of the separator is visualized by dye method changing Reynolds number. Furthermore, effects of size of the inlet and outlet manifolds and shape of ribs near the inlet outlet on the distributions of flow and pressure are examined.

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THE NUMBER OF REPRESENTATIONS OF A POSITIVE INTEGER BY TRIANGULAR, SQUARE AND DECAGONAL NUMBERS

  • Isnaini, Uha;Melham, Ray;Toh, Pee Choon
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.5
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    • pp.1143-1157
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    • 2019
  • Let $T_aD_b(n)$ and $T_aD^{\prime}_b(n)$ denote respectively the number of representations of a positive integer n by $a(x^2-x)/2+b(4y^2-3y)$ and $a(x^2-x)/2+b(4y^2-y)$. Similarly, let $S_aD_b(n)$ and $S_aD^{\prime}_b(n)$ denote respectively the number of representations of n by $ax^2+b(4y^2-3y)$ and $ax^2+b(4y^2-y)$. In this paper, we prove 162 formulas for these functions.

ON FINITE GROUPS WITH THE SAME ORDER TYPE AS SIMPLE GROUPS F4(q) WITH q EVEN

  • Daneshkhah, Ashraf;Moameri, Fatemeh;Mosaed, Hosein Parvizi
    • Bulletin of the Korean Mathematical Society
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    • v.58 no.4
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    • pp.1031-1038
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    • 2021
  • The main aim of this article is to study quantitative structure of finite simple exceptional groups F4(2n) with n > 1. Here, we prove that the finite simple exceptional groups F4(2n), where 24n + 1 is a prime number with n > 1 a power of 2, can be uniquely determined by their orders and the set of the number of elements with the same order. In conclusion, we give a positive answer to J. G. Thompson's problem for finite simple exceptional groups F4(2n).

나머지 수 체계의 부활

  • 예홍진
    • Journal for History of Mathematics
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    • v.12 no.2
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    • pp.47-54
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    • 1999
  • We introduce some historical facts on number theory, especially prime numbers and modular arithmetic. And then, with the viewpoint of computer arithmetic, residue number systems are considered as an alternate to positional number systems so that high performance and high speed computation can be achieved in a specified domain such as cryptography and digital signal processing.

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