• Title/Summary/Keyword: X-vector

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Hardness of Approximation for Two-Dimensional Vector Packing Problem with Large Items (큰 사이즈 아이템들에 대한 2차원 벡터 패킹문제의 어려움)

  • Hwang, Hark-Chin;Kang, Jang-Ha
    • Journal of Korean Institute of Industrial Engineers
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    • v.38 no.1
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    • pp.1-6
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    • 2012
  • We consider a two-dimensional vector packing problem in which each item has size in x- and y-coordinates. The purpose of this paper is to provide a ground work on how hard two-dimensional vector packing problems are for large items. We prove that the problem with each item greater than 1/2-${\varepsilon}$ either in x- or y-coordinates for 0 < ${\varepsilon}$ ${\leq}$ 1/6 has no APTAS unless P = NP.

SEMI-INVARIANT SUBMANIFOLDS OF CODIMENSION 3 IN A COMPLEX SPACE FORM IN TERMS OF THE STRUCTURE JACOBI OPERATOR

  • Ki, U-Hang;Kurihara, Hiroyuki
    • Communications of the Korean Mathematical Society
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    • v.37 no.1
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    • pp.229-257
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    • 2022
  • Let M be a semi-invariant submanifold of codimension 3 with almost contact metric structure (𝜙, 𝜉, 𝜂, g) in a complex space form Mn+1(c), c ≠ 0. We denote by A and R𝜉 the shape operator in the direction of distinguished normal vector field and the structure Jacobi operator with respect to the structure vector 𝜉, respectively. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a scalar 𝜃(< 2c) and any vector fields X and Y on M. In this paper, we prove that if it satisfies R𝜉A = AR𝜉 and at the same time ∇𝜉R𝜉 = 0 on M, then M is a Hopf hypersurface of type (A) provided that the scalar curvature s of M holds s - 2(n - 1)c ≤ 0.

Investigation of the Three-dimensional Turbulent Flow Fields in Cone Type Gas Burner for Furnace - On the Vector Fields and Mean Velocities - (난방기용 콘형 가스버너에서 3차원 난류 유동장 고찰 - 벡터장 및 평균속도에 대하여 -)

  • Kim, J.K.;Jeong, K.J.;Kim, S.W.;Kim, I.K.
    • Journal of Power System Engineering
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    • v.4 no.4
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    • pp.25-31
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    • 2000
  • This paper represents the vector fields and three dimensional mean velocities in the X-Y plane of cone type swirl gas burner measured by using X-probe from the hot-wire anemometer system. This experiment is carried out at flowrate 350 and $450{\ell}/min$ respectively in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component is focused in the narrow slits distributed radially on the edge of a cone type swirl burner, for that reason, there is some entrainment of ambient air in the outer region of the burner and the rotational flow can be shown in the inner region of the burner because mean velocity W is distributed about twice as large as mean velocity V due to inclined flow velocity ejecting from the swirl vanes of a cone type baffle plate of burner. Moreover, the mean velocities are largely distributed near the outer region of burner within $X/R{\fallingdotseq}1.5$, hence, the turbulent characteristics are anticipated to be distributed largely in the center of this region due to the large inclination of mean velocity and swirl effect.

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GENERALIZED CUBIC MAPPINGS OF r-TYPE IN SEVERAL VARIABLES

  • Kang, Dong Seung
    • Journal of the Chungcheong Mathematical Society
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    • v.20 no.1
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    • pp.37-45
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    • 2007
  • Let X, Y be vector spaces. In this paper, we investigate the generalized Hyers-Ulam-Rassias stability problem for a cubic function $f:X{\rightarrow}Y$ satisfies $$r^3f(\frac{\Sigma_{j=1}^{n-1}x_j+2x_n}{r})+r^3f(\frac{\Sigma_{j=1}^{n-1}x_j-2x_n}{r})+8\sum_{j=1}^{n-1}f(x_j)=2f{\sum_{j=1}^{n-1}}x_j)+4{\sum_{j=1}^{n-1}}(f(x_j+x_n)+f(x_j-x_n))$$ for all $x_1,{\cdots},x_n{\in}X$.

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MATCHING THEOREMS AND SIMULTANEOUS RELATION PROBLEMS

  • Balaj, Mircea;Coroianu, Lucian
    • Bulletin of the Korean Mathematical Society
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    • v.48 no.5
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    • pp.939-949
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    • 2011
  • In this paper we give two matching theorems of Ky Fan type concerning open or closed coverings of nonempty convex sets in a topological vector space. One of them will permit us to put in evidence, when X and Y are convex sets in topological vector spaces, a new subclass of KKM(X, Y) different by any admissible class $\mathfrak{u}_c$(X, Y). For this class of set-valued mappings we establish a KKM-type theorem which will be then used for obtaining existence theorems for the solutions of two types of simultaneous relation problems.

SINGULAR THIRD-ORDER 3-POINT BOUNDARY VALUE PROBLEMS

  • Palamides, Alex P.
    • Journal of applied mathematics & informatics
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    • v.28 no.3_4
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    • pp.697-710
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    • 2010
  • In this paper, we prove existence of infinitely many positive and concave solutions, by means of a simple approach, to $3^{th}$ order three-point singular boundary value problem {$x^{\prime\prime\prime}(t)=\alpha(t)f(t,x(t))$, 0 < t < 1, $x(0)=x'(\eta)=x^{\prime\prime}(1)=0$, (1/2 < $\eta$ < 1). Moreover with respect to multiplicity of solutions, we don't assume any monotonicity on the nonlinearity. We rely on a combination of the analysis of the corresponding vector field on the phase-space along with Knesser's type properties of the solutions funnel and the well-known Krasnosel'ski$\breve{i}$'s fixed point theorem. The later is applied on a new very simple cone K, just on the plane $R^2$. These extensions justify the efficiency of our new approach compared to the commonly used one, where the cone $K\;{\subset}\;C$ ([0, 1], $\mathbb{R}$) and the existence of a positive Green's function is a necessity.

Gene Transfer into Chicken Embryos using Defective Retroviral Vectors Packaged with Vesicular Stomatitis Virus G Glycoprotein Envelopes (Vesicular Stomatitis Virus G Glycoprotein Envelope으로 포장된 Defective Retroviral Vector를 이용한 닭의 배로의 유전자 전이)

  • 권모선;임은정;허영태;이훈택;이영만;김태완
    • Korean Journal of Animal Reproduction
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    • v.25 no.2
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    • pp.171-180
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    • 2001
  • Compared to other gene transfer system, the advantages of retrovirus-mediated gene transfer are technical ease, efficient expression and genetic stability. Despite the high potency of the retrovirus vector system in gene transfer, one of the drawbacks is a difficulty in concentration of virus stock. To overcome this problem, we tested a new retrovirus vector system producing the progeny retrovirus particles encapsidated with VSV-G (vesicular stomatitis virus G glycoprotein). The infectivity of this virus was not sacrificed by ultracentrifugal concentration and the host cell range extended from all mammalian to fish embryos. Virus titer after 1,000 x concentration was more than 10$^{8}$ CFU/ $m\ell$ on most of the target cell lines. We applied this pantropic viruses in transgenic chicken production by injecting the concentrated (100$\times$) stock into subgerminal cavity of stage X chicken embryos. The survival rate of chicken embryos after injection was about 20% and gene integration rate in surviving embryos was scored almost 100%. Analyses of RT-PCR and fluorescence microscopy, however, showed no evidence of the transgene expression.

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ON COMBINATORICS OF KONHAUSER POLYNOMIALS

  • Kim, Dong-Su
    • Journal of the Korean Mathematical Society
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    • v.33 no.2
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    • pp.423-438
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    • 1996
  • Let L be a linear functional on the vector space of polynomials in x. Let $\omega(x)$ be a polynomial in x of degree d, for some positive integer d. We consider two sets of polynomials, ${R_n (x)}_{n \geq 0}, {S_n(x)}_{n \geq 0}$, such that $R_n(x)$ is a polynomial in x of degree n and $S_n(x)$ is a polynomial in $\omega(x)$ of degree n. (So $S_n(x)$ is a polynomial in x of degree dn.)

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