• Communications of the Korean Mathematical Society
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• v.25 no.3
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• pp.349-364
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• 2010

P. M. Cohn called a ring R reversible if whenever ab = 0, then ba = 0 for a, $b\;{\in}\;R$. Commutative rings and reduced rings are reversible. In this paper, we extend the reversible condition of a ring as follows: Let R be a ring and $\alpha$ an endomorphism of R, we say that R is right (resp., left) $\alpha$-shifting if whenever $a{\alpha}(b)\;=\;0$ (resp., $\alpha{a)b\;=\;0$) for a, $b\;{\in}\;R$, $b{\alpha}{a)\;=\;0$ (resp., $\alpha(b)a\;=\;0$); and the ring R is called $\alpha$-shifting if it is both left and right $\alpha$-shifting. We investigate characterizations of $\alpha$-shifting rings and their related properties, including the trivial extension, Jordan extension and Dorroh extension. In particular, it is shown that for an automorphism $\alpha$ of a ring R, R is right (resp., left) $\alpha$-shifting if and only if Q(R) is right (resp., left) $\bar{\alpha}$-shifting, whenever there exists the classical right quotient ring Q(R) of R.

• Journal of applied mathematics & informatics
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• v.3 no.1
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• pp.65-78
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• 1996

The properties of a toric variety have strong connection with the combinatorial structure of the corresponding fan and the rela-tions among the generators. Using this fact we have described explic-itly the Chow ring for a Q-factorial toric variety as the Stanley-Reisner ring for the corresponding fan modulo the linear equivalence relation. In this paper we calculate the Chow ring for 3-dimensional Q-factorial toric varieties having one bad isolated singularity.

• Kyungpook Mathematical Journal
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• v.18 no.1
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• pp.105-107
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• 1978

Considering the prime z-filters on a topological space X through the structures of the ring C(X) of continuous functions. a prime z-filter is uniquely determined by a primary z-ideal in the ring C(X), i. e., they have a one-to-one correspondence. Any primary ideal is contained in a unique maximal ideal in C(X). Denoting $\mathfrak{F}(X)$, $\mathfrak{Q}(X)$, 𝔐(X) the prime, primary-z, maximal spectra, respectively, $\mathfrak{Q}(X)$ is neither an open nor a closed subspace of $\mathfrak{F}(X)$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.533-534
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• 2008

This paper presents a multi-phase ring VCO for low-cost, low-power GPS receiver. In the RF band used in GPS, L1 band is now in commercial-use and L2,L5 are predicting to be commercial-use soon. Thus Wide band PLL and Cost-effective IC solutions are required for future multi-band GPS receiver that received three types band at once. A new PLL architecture for multi-band GPS application is proposed. Ring VCO is even smaller than LC-VCO and a good alternative for low-cost solution. Proposed multi-phase ring VCO offers wide frequency range covering L1, L2, and L5 band, 20% reduction of area, 23% reduction of PLL power and can generate I/Q without extra I/Q generator.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.477-496
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• 2022

During a survey of free-living marine nematodes of Korea, two new marine desmoscolecid nematodes belonging to subgenus Quadricoma Filipjev, 1922 were discovered. Tricoma (Q.) jejuensis sp. nov. and T.(Q.) unipapillata sp. nov. are described based on specimens obtained from washings of coarse sediments from eastern and southern coasts of Korea. Tricoma (Q.) jejuensis sp. nov. is characterized by having 33 quadricomoid body rings and inversion at main ring 23, pentagonal head with truncated anterior end, a pair of ocelli situated at main ring 6, somatic setae comprising of 8 pairs of subdorsal setae and 12 pairs of subventral setae, and relatively short spicules (42-46 ㎛ long). Tricoma (Q.) unipapillata sp. nov. is characterized by 44 quadricomoid body rings and inversion at main ring 32, somatic setae comprising of 7 pairs of subdorsal setae and 10 pairs of subventral setae, globular head truncated anterior end, relatively short and stumpy cephalic setae with cuticular flange, one single naked ventral median genital papillae situated on main ring 20, and spicules with a proximally marked capitulum. Detailed morphological descriptions and illustrations of these two new species are provided in this study.

• Korean Journal of Mathematics
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• v.28 no.1
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• pp.31-47
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• 2020

In this paper, we discuss in detail some of the properties of the new kind of (∈, ∈ ∨q)-fuzzy ideals in Near-ring. The concept of (∈, ∈ ∨q^δ₀)-fuzzy ideal of Near-ring is introduced and some of its related properties are investigated.

• Journal of the Korean Mathematical Society
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• v.53 no.6
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• pp.1445-1457
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• 2016

For a positive integer N divisible by 4, let ${\mathcal{O}}^1_N({\mathbb{Q}})$ be the ring of weakly holomorphic modular functions for the congruence subgroup ${\Gamma}^1(N)$ with rational Fourier coefficients. We present explicit generators of the ring ${\mathcal{O}}^1_N({\mathbb{Q}})$ over ${\mathbb{Q}}$ in terms of both Fricke functions and Siegel functions, from which we are able to classify all Fricke families of such level N.

• Bulletin of the Korean Mathematical Society
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• v.32 no.2
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• pp.145-152
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• 1995

From now on, we assume that a ring R has an identity 1. We have the following Lemma from Park[2].

• The Pure and Applied Mathematics
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• v.30 no.4
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• pp.397-406
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• 2023

Let R be a commutative ring with identity, X be an indeterminate over R, and R[X] be the polynomial ring over R. In this paper, we study when R[X] is a radically principal ideal ring. We also study the t-operation analog of a radically principal ideal domain, which is said to be t-compactly packed. Among them, we show that if R is an integrally closed domain, then R[X] is t-compactly packed if and only if R is t-compactly packed and every prime ideal Q of R[X] with Q ∩ R = (0) is radically principal.

• Bulletin of the Korean Mathematical Society
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• v.55 no.2
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• pp.573-586
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• 2018

Let R be a noncommutative prime ring of characteristic different from 2, Q be its maximal right ring of quotients and C be its extended centroid. Suppose that $f(x_1,{\ldots},x_n)$ be a noncentral multilinear polynomial over $C,b{\in}Q,F$ a b-generalized derivation of R and d is a nonzero derivation of R such that d([F(f(r)), f(r)]) = 0 for all $r=(r_1,{\ldots},r_n){\in}R^n$. Then one of the following holds: (1) there exists ${\lambda}{\in}C$ such that $F(x)={\lambda}x$ for all $x{\in}R$; (2) there exist ${\lambda}{\in}C$ and $p{\in}Q$ such that $F(x)={\lambda}x+px+xp$ for all $x{\in}R$ with $f(x_1,{\ldots},x_n)^2$ is central valued in R.