• 충청수학회지
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• 제34권1호
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• pp.1-15
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• 2021

In the recent papers, S'anchez-Reyes [Appl. Math. Model. 40 (2016), 1676-1682] described the method for finding a minimal surface through a geodesic, and Li et al. [Appl. Math. Model. 37 (2013), 6415-6424] studied the approximation of minimal surfaces with a geodesic from Dirichlet function. In the present article, we consider an isoparametric surface generated by Frenet frame of a curve introduced by Wang et al. [Comput. Aided Des. 36 (2004), 447-459], and give the necessary and sufficient condition to satisfy both geodesic of the curve and minimality of the surface. From this, we construct minimal surfaces in terms of constant curvature and torsion of the curve. As a result, we present a new approach for constructions of the minimal surfaces from a prescribed closed geodesic and unclosed geodesic, and show some new examples of minimal surfaces with a circle and a helix as a geodesic. Our approach can be used in design of minimal surfaces from geodesics.

• 산업경영시스템학회지
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• 제20권43호
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• pp.241-247
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• 1997

This paper is concerned with cost analysis model in free-replacement policy. The free-replacement policy with minimal repair is considered as follows; in a manufacturer's view point operating unit is periodically replaced, if a failure occurs between minimal repair and periodic maintenance time, unit is remained in a failure condition. Also unit undergoes minimal repair at failures in minimal-repair interval. Then total expected cost is calculated according to the parameter of failure distribution in a view of consumer's. The expected costs are included repair cost and usage cost: operating, fixed, minimal repair and loss cost. Numerical example is shown in which failure time of item has weibull distribution.

• 산업경영시스템학회지
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• 제19권39호
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• pp.89-98
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• 1996

This paper is concerned with cost analysis model in free -replacement policy under the periodic maintenance policy The free-replacement policy with minimal repairable item is considered as follows; in a manufacturer's view point operating unit is periodically replaced, if a failure occurs between minimal repair and periodic maintenance time, unit is remained in a failure condition. Also unit undergoes minimal repair at failures in minimal-repair interval. Then total expected cost per unit time is calculated according to maintenance period Tin a viewpoint of consumer's. The expected costs are included repair cost and usage cost: operating, fixed, minimal repair and loss cost. Numerical example is shown in which failure time of item has beta distribution.

• Journal of applied mathematics & informatics
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• 제4권1호
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• pp.249-261
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• 1997

We find a necessary and sufficient condition for a $\kappa$-confi-guration $\mathbb{X}$ in $\mathbb{P}^2$ to be in generic position. We obtain the number and degrees of minimal generators of some Gorenstein ideals of codimension 3 and so obtain their minimal free resolution s of these ideals.

• 충청수학회지
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• 제34권4호
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• pp.379-385
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• 2021

We consider the local uniqueness of a catenoid under the condition for the Gaussian curvature analogous to Bianchi surfaces. More precisely, if a nonplanar minimal surface in ℝ³ has the Gaussian curvature $K={\frac{1}{(U(u)+V(v))^2}}$ for any functions U(u) and V (v) with respect to a line of curvature coordinate system (u, v), then it is part of a catenoid. To do this, we use the relation between a conformal line of curvature coordinate system and a Chebyshev coordinate system.

• Journal of applied mathematics & informatics
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• 제19권1_2호
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• pp.545-550
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• 2005

We find a necessary and sufficient condition that the number of some Betti numbers and shifts appear in the last free module Fn of Fx based on type vectors, where X is a finite set of points in $P^n$.

• 충청수학회지
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• 제21권4호
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• pp.555-562
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• 2008

In this paper, it will be given a necessary and sufficient condition for a function to be an r-homomorphism in connection with the subgroups of the automorphism group of a universal minimal set.

• 대한수학회보
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• 제45권4호
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• pp.797-800
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• 2008

Let R be a ring and I be a proper ideal of R. For the case of R being commutative, Anderson proved that (*) there are only finitely many prime ideals minimal over I whenever every prime ideal minimal over I is finitely generated. We in this note extend the class of rings that satisfies the condition (*) to noncommutative rings, so called homomorphically IFP, which is a generalization of commutative rings. As a corollary we obtain that there are only finitely many minimal prime ideals in the polynomial ring over R when every minimal prime ideal of a homomorphically IFP ring R is finitely generated.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.639-642
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• 2004

The pH as a control parameter for oxidation-reduction potential (ORP) was investigated through the denitrification by Ochrobactrum anthropi SY509 under non-growing condition. The optimal pH of nitrate reductase was 7.0, and the minimal ORP level was －250 mV for the denitrification under aerobic condition. In the case of anaerobic condition, the optimal pHs of nitrate and nitrite reductase were shifted to 10.0 and 9.0, respectively, and the minimal ORP levels of nitrate and nitrite reductase were decreased to －370 mV and －340mV, respectively. In the case of alkaline pH and anaerobic condition, the denitrification efficiency of nitrate was increased up to about 2-fold over that of neutral pH and anaerobic condition. Therefore, the combined control of pH and ORP in the anaerobic condition is shown to be an important parameter in the biological denitrification process.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제1권1호
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• pp.1-6
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• 1994

In this paper, some properties for a PI-ring satisfying the descending chain condition on essential left ideals are studied: Let R be a ring with a polynomial identity satisfying the descending chain condition on essential ideals. Then all minimal prime ideals in R are maximal ideals. Moreover, if R has only finitely many minimal prime ideals, then R is left and right Artinian. Consequently, if every primeideal of R is finitely generated as a left ideal, then R is left and right Artinian. A finitely generated PI-algebra over a commutative Noetherian ring satisfying the descending chain condition on essential left ideals is a finite module over its center.(omitted)