• 제목/요약/키워드: r-lattice

검색결과 242건 처리시간 0.019초

THE TOEPLITZ OPERATOR INDUCED BY AN R-LATTICE

  • Kang, Si Ho
    • 충청수학회지
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    • 제25권3호
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    • pp.491-499
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    • 2012
  • The hyperbolic metric is invariant under the action of M$\ddot{o}$bius maps and unbounded. For 0 < $r$ < 1, there is an r-lattice in the Bergman metric. Using this r-lattice, we get the measure ${\mu}_r$ and the Toeplitz operator $T^{\alpha}_{\mu}_r$ and we prove that $T^{\alpha}_{\mu}_r$ is bounded and $T^{\alpha}_{\mu}_r$ is compact under some condition.

The Construction of an Efficient Incomplete Block Design by Almost Otrhogonal Latin Squares of Order 6

  • Dongwoo Kim
    • Communications for Statistical Applications and Methods
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    • 제4권3호
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    • pp.707-714
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    • 1997
  • The littice designs have prove efficient but they are not alwasy available. This article proposes an alternative, an almost lattice design, of the triple lattice design (v=36, k=6, r=4) which is not available. Here, we compare the almost lattice design to the .alpha.-design (v=36, k=6, r=4) which is another alternative of the triple lattice design (v=36, k=6, r=4). Consequently, we show the almost lattice design is a more efficient alternative than the $\alpha$-design through A-, D-, and E-optimality.

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Positive implicative and associative filters of lattice implication algebras

  • Jun, Young-Bae;Yang Xu;Keyun Qin
    • 대한수학회보
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    • 제35권1호
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    • pp.53-61
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    • 1998
  • We introduce the concepts of a positive implicative filter and an associative filter in a lattice implication algebra. We prove that (i) every positive implicative filter is an implicative filter, and (ii) every associative filter is a filter. We provide equivalent conditions for both a positive implicative filter and an associative filter.

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UNIMODULAR GROUPS OF TYPE ℝ3 ⋊ ℝ

  • Lee, Jong-Bum;Lee, Kyung-Bai;Shin, Joon-Kook;Yi, Seung-Hun
    • 대한수학회지
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    • 제44권5호
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    • pp.1121-1137
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    • 2007
  • There are 7 types of 4-dimensional solvable Lie groups of the form ${\mathbb{R}^3}\;{\times}_{\varphi}\;{\mathbb{R}}$ which are unimodular and of type (R). They will have left. invariant Riemannian metrics with maximal symmetries. Among them, three nilpotent groups $({\mathbb{R}^4},\;Nil^3\;{\times}\;{\mathbb{R}\;and\;Nil^4)$ are well known to have lattices. All the compact forms modeled on the remaining four solvable groups $Sol^3\;{\times}\;{\mathbb{R}},\;Sol_0^4,\;Sol_0^'4\;and\;Sol_{\lambda}^4$ are characterized: (1) $Sol^3\;{\times}\;{\mathbb{R}}$ has lattices. For each lattice, there are infra-solvmanifolds with holonomy groups 1, ${\mathbb{Z}}_2\;or\;{\mathbb{Z}}_4$. (2) Only some of $Sol_{\lambda}^4$, called $Sol_{m,n}^4$, have lattices with no non-trivial infra-solvmanifolds. (3) $Sol_0^{'4}$ does not have a lattice nor a compact form. (4) $Sol_0^4$ does not have a lattice, but has infinitely many compact forms. Thus the first Bieberbach theorem fails on $Sol_0^4$. This is the lowest dimensional such example. None of these compact forms has non-trivial infra-solvmanifolds.

COMPUTATION OF AERODYNAMIC SOUNDS AT LOW MACH NUMBERS USING FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

  • Kang H. K;Tsutahara M;Shikata K;Kim E. R;Kim Y. T;Lee Y. H
    • 한국전산유체공학회지
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    • 제10권1호
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    • pp.8-15
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    • 2005
  • Aerodynamic sounds generated by a uniform flow around a two-dimensional circular cylinder at Re=150 are simulated by applying the finite difference lattice Boltzmann method. Thethird-order-accurate up-wind scheme (UTOPIA) is used for the spatial derivatives, and the second-order-accurate Runge-Kutta scheme is applied for the time marching. We have succeed in capturing very small pressure fluctuations with the same frequency of the Karman vortex street compared with the pressure fluctuation around a circular cylinder. The propagation velocity of the acoustic waves shows that the points of peak pressure are biased upstream due to the Doppler effect in the uniform flow. For the downstream, on the other hand, it is faster. It is also apparent that the amplitude of sound pressure is proportional to r /sup -1/2/,r being the distance from the center of the circular cylinder. To investigate the effect of the lattice dependence, furthermore, 2D computations of the tone noises radiated by a square cylinder and NACA0012 with a blunt trailing edge at high incidence and low Reynolds number are also investigate.

Comparative structural analysis of lattice hybrid and tubular wind turbine towers

  • Kumaravel, R.;Krishnamoorthy, A.
    • Wind and Structures
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    • 제30권1호
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    • pp.29-35
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    • 2020
  • This paper presents a comparative structural analysis of lattice hybrid tower with six legs with conventional tubular steel tower for an onshore wind turbine using finite element method. Usually a lattice hybrid tower will have a conventional industry standard 'L' profile section for the lattice construction with four legs. In this work, the researcher attempted to identify and analyze the strength of six legged lattice hybrid tower designed with a special profile instead of four legged L profile. And to compare the structural benefits of special star profile with the conventional tubular tower. Using Ansys, a commercial FEM software, both static and dynamic structural analyses were performed. A simplified finite element model that represents the wind turbine tower was created using Shell elements. An ultimate load condition was applied to check the stress level of the tower in the static analysis. For the dynamic analysis, the frequency extraction was performed in order to obtain the natural frequencies of the tower.

Space Group $R\={3}c$(167)과 Tris(1,2,3,4-tetraphenylbuta-1,3-dienyl)cyclotriphosphazene의 結晶構造 (Space Group $R\={3}c$ = $R\={3}2/c$(167) and the Crystal Structure of Tris(1,2,3,4-tetraphenylbuta-1,3-dienyl)cyclotriphosphazene)

  • 김영상;고재중;강상욱;이영주;강유진;한원식;박영수;서일환
    • 한국결정학회지
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    • 제15권1호
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    • pp.9-17
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    • 2004
  • Trigonal system에 屬한 25個 space group들 中 18個는 hexagonal axes만을 나타내는 lattice letter p로 表示되고, 나머지 7個의 rhombohedral space groups R3(146), $R\={3}$(148), R32(155), R3m(160), R3c(161), $R\={3}m$(166), $R\={3}c$(167)은 첫째 3개의 lattice points (0, 0, 0), (2/3, 1/3, 1/3), (1/3, 2/3, 2/3)를 갖는 hexagonal cell in obverse setting과 둘째 primitive rhombohedral cell의 두 가지로 表示된다. 本 論文에서는 space group $R\={3}c$(167)에 대하여 論한 後 이 space group에 屬한 化合物인 tris(1,2,3,4-tetraphenylbuta-1,3-dienyl)cyclotriphosphazene, $C_{84}H_{60}N_3P_3$의 構造를 hexagonal 및 rhombohedral cell 의 양쪽으로 糾明하여 發表하였다.

A Study on Feasibility of Hexagonal Phase ZnS:$Mn^{2+}$ Phosphor for Low-voltage Display Applications

  • Shin, Sang-Hoon;Lee, Sang-Hyuk;You, Yong-Chan;Jung, Joa-Young;Park, Chang-Won;Chang, Dong-Sik
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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    • pp.815-818
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    • 2002
  • Mn doped hexagonal phase of ZnS has been studied as a yellow-orange phosphor for the application to fluorescent displays operated at low voltages. It was found that luminescence from $Mn^{2+}$ was increased as the Mn concentration was increased up to1.2 mol% of host lattice. This study has been attempted by adding trivalent ions such as $Al^{3+}$ or $Bi^{3+}$ to ZnS:Mn as an agent to do the efficient incorporation of Mn ions into ZnS:Mn lattice, resulting in a significant improvement in the phosphor performance, especially at low voltages.

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