• Title, Summary, Keyword: upper to zero

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Kaplansky-type Theorems, II

  • Chang, Gyu-Whan;Kim, Hwan-Koo
    • Kyungpook Mathematical Journal
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    • v.51 no.3
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    • pp.339-344
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    • 2011
  • Let D be an integral domain with quotient field K, X be an indeterminate over D, and D[X] be the polynomial ring over D. A prime ideal Q of D[X] is called an upper to zero in D[X] if Q = fK[X] ${\cap}$ D[X] for some f ${\in}$ D[X]. In this paper, we study integral domains D such that every upper to zero in D[X] contains a prime element (resp., a primary element, a t-invertible primary ideal, an invertible primary ideal).

GLOBAL SHAPE OF FREE BOUNDARY SATISFYING BERNOULLI TYPE BOUNDARY CONDITION

  • Lee, June-Yub;Seo, Jin-Keun
    • Journal of the Korean Mathematical Society
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    • v.37 no.1
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    • pp.31-44
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    • 2000
  • We study a free boundary problem satisfying Bernoulli type boundary condition along which the gradient of a piecewise harmonic solution jumps zero to a given constant value. In such problem, the free boundary splits the domain into two regions, the zero set and the harmonic region. Our main interest is to identify the global shape and the location of the zero set. In this paper, we find the lower and the upper bound of the zero set. In a convex domain, easier estimation of the upper bound and faster disk test technique are given to find a rough shape of the zero set. Also a simple proof on the convexity of zero set is given for a connected zero set in a convex domain.

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Large eddy simulation of flow around a stay cable with an artificial upper rivulet

  • Zhao, Yan;Du, Xiaoqing;Gu, Ming;Yang, Xiao;Li, Junjun;He, Ping
    • Wind and Structures
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    • v.26 no.4
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    • pp.215-229
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    • 2018
  • The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.

A Prospective Study of Clinical and Radiological Outcomes of Zero-Profile Cage Screw Implants for Single-Level Anterior Cervical Discectomy and Fusion: Is Segmental Lordosis Maintained at 2 Years?

  • Basu, Saumyajit;Rathinavelu, Sreeramalingam
    • Asian Spine Journal
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    • v.11 no.2
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    • pp.264-271
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    • 2017
  • Study Design: Prospective cohort study. Purpose: To study clinicoradiological parameters of zero-profile cage screw used for anterior cervical discectomy and fusion (ACDF). Overview of Literature: Radiological parameters of various implants used for ACDF are available, but those for zero-profile cage are sparse. Methods: Patients with unilateral intractable brachialgia due to single-level cervical disc prolapse between April 1, 2011 and March 31, 2014 were included. Clinical assessment included arm and neck pain using visual analogue score (VAS) and neck disability index (NDI) scores. Radiological assessment included motion segment height, adjacent disc height (upper and lower), segmental and cervical lordosis, implant subsidence, and pseudoarthrosis. Follow-ups were scheduled at 1, 3, 6, 12, and 24 months. Results: Thirty-four patients (26 males, 8 females) aged 30-50 years (mean, 42.2) showed excellent clinical improvement based on VAS scores (7.4-0 for arm and 2.0-0.6 for neck pains). Postoperative disc height improved by 11.33% (p<0.001), but at 2 years, the score deteriorated by 7.03% (p<0.001). Difference in the adjacent segment disc height at 2 years was 0.08% (p=0.8) in upper and 0.16% (p<0.001) in lower disc spaces. Average segmental lordosis achieved was $5.59^{\circ}$ (p<0.001) from a preoperative kyphosis of $0.88^{\circ}$; at 2 years, an average loss of $7.05^{\circ}$ (p<0.001) occurred, resulting in an average segmental kyphosis of $1.38^{\circ}$. Cervical lordosis improved from $11.59^{\circ}$ to $14.88^{\circ}$ (p=0.164), and at 2 years, it progressively improved to $22.59^{\circ}$ (p<0.001). Three patients showed bone formation and two mild protrusion of the implant at 2 years without pseudoarthrosis/implant failure. Conclusions: The zero-profile cage screw device provides good fusion and cervical lordosis but is incapable of maintaining the segmental lordosis achieved up to a 2-year follow-up. We also recommend caution when using it in patients with small vertebrae.

An Upper Bound Solution of Tube Drawing (관인발의 상계해석)

  • 엄경근;이동녕
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.40-47
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    • 1996
  • An upper bound solution of tube drawing process using a fixed tapered plug has been obtained , which reduces to an solution for tube sinking by setting friction factor between tube and plug at zero. Effects of various process paraments have been discussed based on the solution.

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An Algorithm on Three-Dimensional Loading Problem (3차원 적재문제의 최적 해법)

  • 김상열;박순달
    • Journal of the Korean Operations Research and Management Science Society
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    • v.23 no.2
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    • pp.1-13
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    • 1998
  • The purpose of this paper is to formulate the three-dimensional loading problem and to develop an exact algorithm. The three-dimensional loading problem is not only to load as many boxes as possible, but also to ensure load stability. In this Paper, we propose formulation by zero-one integer programming. Further we propose as an algorithm the branch-and-bound enforced by efficient bounding criteria. As an upper bound, we use the solution of the Lagrangean relaxation problem which relaxes constraints of zero-one IP, and as a lower bound, we use a heuristic solution induced by the solution of the Lagrangean relaxation problem. Last, we show computational experiments on convergency of upper and lower bounds.

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A GENERALIZATION OF SYMMETRIC RING PROPERTY

  • Kim, Hong Kee;Kwak, Tai Keun;Lee, Seung Ick;Lee, Yang;Ryu, Sung Ju;Sung, Hyo Jin;Yun, Sang Jo
    • Bulletin of the Korean Mathematical Society
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    • v.53 no.5
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    • pp.1309-1325
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    • 2016
  • This note focuses on a ring property in which upper and lower nilradicals coincide, as a generalizations of symmetric rings. The concept of symmetric ideal and ring in the noncommutative ring theory was initially introduced by Lambek, as an extension of the usual commutative ideal theory. The investigation of symmetric rings provided many useful results to the study in the noncommutative ring theory. So the results obtained from this study may be applicable to observing the structure of zero divisors in various kinds of algebraic systems containing matrix rings and polynomial rings.

On the Performance of Zero-Forcing Beamforming with Semi-orthogonal User Selection in Clustered Cell Coordinated Transmission (제로 포싱 (zero-forcing) 빔 형성과 반직교 기반 사용자 선정을 이용한 클러스터 (cluster) 기반 셀 협력 전송 방식의 성능에 대한 연구)

  • Yang, Jang-Hoon;Jang, Seung-Hun;Kim, Dong-Ku
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.10
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    • pp.1-9
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    • 2008
  • In this paper, a simple and efficient three cell based clustered-cell coordination is proposed with well hewn zero-forcing beamforming (ZF-BF) with a semi-orthogonal user selection (SUS) as transmission and scheduling scheme. For a modified Wyner's channel model with two classes of user groups for a hexagonal cellular system, the upper bound of asymptotic sum rate scaling of ZF-BF in a proposed coordination is shown to be proportional to the number of transmit antennas and double logarithms of the number of users. The numerical results verify the efficiency of the proposed cell coordination. It is also numerically shown that ZF-BF with the SUS in CCCT actually achieves the upper bound of asymptotic sum rate sum rate scaling.

DIFFERENTIAL EQUATIONS ON WARPED PRODUCTS (II)

  • JUNG, YOON-TAE
    • Honam Mathematical Journal
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    • v.28 no.3
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    • pp.399-407
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    • 2006
  • In this paper, we consider the problem of achieving a prescribed scalar curvature on warped product manifolds according to fiber manifolds with zero scalar curvature.

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A Hardware Reduced Multiplier for Low Power Design (저전력 설계를 위한 면적 절약형 곱셈기 구조에 관한 연구)

  • 이광현;임종석
    • Proceedings of the IEEK Conference
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    • pp.1085-1088
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    • 1998
  • In this paper, we propose a hardware reduced multiplier for DSP applications. In many DSP application, all of multiplier products were not used, but only upper bits of rpoduct were used. Kidambi proposed truncated unsigned multiplier for this idea. In this paper, we abopt this scheme to Booth multiplier which can be used for real DSP systems. Also, zero input guarantees zero output that was not provided in the previous work.

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