• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.261-267
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• 1995

Using the dual of a categorical definition of an injective envelope, Enochs defined an injective cover. In this paper we will show how injective covers can be used to characterize several well known classes of rings.

• Journal of the Chungcheong Mathematical Society
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• v.19 no.3
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• pp.225-229
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• 2006

In this paper, we introduce some concepts of ${\Gamma}$-near-ring and obtain their properties on ${\Gamma}$-near-rings through regularity conditions.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.730-737
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• 2013

The purpose of this study is to investigate vasorelaxant effect of Epimedium koreanum(EK) extract on rabbit carotid artery. In this study, to determine vasorelaxant effect of EK extract on rabbit carotid artery, arterial rings with intact or damaged endothelium were used for experiment using organ bath, and were contracted by norepinephrine(NE). After being contracted, arterial rings were treated with EK extract in a dose-dependent manner To study its mechanism, the contracted arterial rings induced by NE were pretreated with indomethacin(IM), $N_{\omega}$-nitro-L-arginine(L-NNA), methylene blue(MB) or tetraethylammonium chloride(TEA) and 0.1 $mg/m{\ell}$ EK extract was added. To analyze the effect of the EK extract on influx of extracellular calcium chloride($Ca^{2+}$) in rabbit carotid artery, in $Ca^{2+}$-free krebs solution, krebs solution containing 1 mM $Ca^{2+}$ was infused into the contracted arterial ring by NE after pretreatment of EK extract. To measure the cytotoxicity of the EK extract, cell viability of human umbilical vein endothelial cell(HUVEC) was measured by MTT assay, and nitric oxide(NO) was measured by Griess reagent. The EK extract significantly was relaxed the arterial ring with intact endothelium contracted by NE, but the vasorelaxant effect of the EK extract was inhibited in the arterial rings with damaged endothelium. The vasorelaxant effect of the EK extract was not different between the IM-pretreatedand and non-treated arterial rings. The vasorelaxant effect of EK extract were significantly inhibited, when arterial rings were pretreated with L-NNA, TEA, MB. And in $Ca^{2+}$-free krebs solution, increasing of arterial contraction by $Ca^{2+}$ addition were also inhibited by the treatment of EK, but not significant. The treatment of EK extract was increased NO concentration in HUVEC. This study suggested that the vasorelaxant effect of EK extract would be related with EDHF and NO production and increasing of cyclic GMP.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.196-208
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• 2005

In multiprocessor systems, interconnection network design is critical for overall system performance. Popular interconnection networks, which are generally considered, are meshes, rings, and hierarchical rings. In this paper, we propose (')Torus Ring('), which is a modified version of hierarchical ring. Torus Ring has the same complexity as the hierarchical rings, but the only difference is the way it connects the local rings. It has an advantage over the hierarchical rings when the destination of a packet is the neighbor local ring in the reverse direction. Though the average number of hops in Torus Ring is equal to that of the hierarchical rings when assuming the uniform distribution of each transaction, the benefits of the number of hops are expected to be larger because of the spatial locality in the real environment of parallel programming. In the simulation results, latencies in the interconnection network are reduced by up to 19$\%$, and the execution times are reduced by up to 10$\%$.

• The Journal of Korean Medicine
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• v.19 no.2
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• pp.228-243
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• 1998

This study was undertaken to evaluate the effect of Sunghyangchungisan (SHCS) on the regulation of vascular tone. Vascular rings isolated from rabbit carotid artery were myographed isometrically in isolated organ baths and the effect of SHCS on contractile activities were determined. SHCS relaxed the arterial rings which were pre-contracted by phenylephrine(PE). The responses to SHCS were partially dose-dependent at concentrations lower than 0.5 mg/ml. When SHCS was applied prior to the exposure to PE, it inhibited the PE-induced contraction by a similar magnitude which was comparable to the relaxation of pre-contracted arterial rings. Washout of SHCS after observing its relaxant effect resulted in a full recovery of PE-induced contractions, indicating that the action mechanism is reversible. The observation that SHCS did not change the $ED_{50}$ of PE on its dose-response curve ruled out the possible interaction of SHCS and ${\alpha}-receptor$. The relaxant effect of SHCS was not affected by removal of endothelium, and pretreatment of the arterial rings with methylene blue or nitro-L-arginine. This results suggest that the action of SHCS is not mediated by endothelium nor soluble guanylate cyclase. SHCS relaxed high $K^{+}-induced$ contractions as well, whereas it failed to relax phorbol ester-induced contractions. When contraction was induced by additive application of $Ca^{2+}$ in arterial rings which were pre-depolarized by high $K^+$ in a $Ca^{2+}-free$ solution, the relaxant effect of SHCS was attenuated by increasing the $Ca^{2+}$ concentration. SHCS, when applied to the arterial rings pre-contracted by PE and then relaxed by nifedipine, a $Ca^{2+}$ channel blocker, did not show additive relaxation. From above results, it is suggested that SHCS relax PE-induced contraction of rabbit carotid artery in an endothelium-independent manner, and inhibition of $Ca^{2+}$ influx may contribute to the underling mechanism.

• Kyungpook Mathematical Journal
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• v.46 no.4
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• pp.603-613
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• 2006

Near-rings considered are right near-rings and R is a near-ring. $J_0^r(R)$, the right Jacobson radical of R of type-0, was introduced and studied by the present authors. In this paper $J_1^r(R)$ and $J_2^r(R)$, the right Jacobson radicals of R of type-1 and type-2 are introduced. It is proved that both $J_1^r$ and $J_2^r$ are radicals for near-rings and $J_0^r(R){\subseteq}J_1^r(R){\subseteq}J_2^r(R)$. Unlike the left Jacobson radical classes, the right Jacobson radical class of type-2 contains $M_0(G)$ for many of the finite groups G. Depending on the structure of G, $M_0(G)$ belongs to different right Jacobson radical classes of near-rings. Also unlike left Jacobson-type radicals, the constant part of R is contained in every right 1-modular (2-modular) right ideal of R. For any family of near-rings $R_i$, $i{\in}I$, $J_{\nu}^r({\oplus}_{i{\in}I}R_i)={\oplus}_{i{\in}I}J_{\nu}^r(R_i)$, ${\nu}{\in}\{1,2\}$. Moreover, under certain conditions, for an invariant subnear-ring S of a d.g. near-ring R it is shown that $J_2^r(S)=S{\cap}J_2^r(R)$.

• Bulletin of the Korean Mathematical Society
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• v.42 no.3
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• pp.527-534
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• 2005

We consider countable rings with ascending chain condition on right annihilators. We determine the structure of a countable right p-injective Baer ring, a countable semi prime quasi-Baer ring and a countable quasi-Baer biregular ring.

• Bulletin of the Korean Mathematical Society
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• v.39 no.1
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• pp.1-8
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• 2002

We characterize the commutative Artinian rings R every proper quotient ring (respectively every proper ideal) in which is invariant with respect to all derivations.

• Kyungpook Mathematical Journal
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• v.45 no.2
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• pp.249-254
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• 2005

Let N be a prime left near-ring with multiplicative center Z and f be a generalized $({\sigma},{\tau})-derivation$ associated with d. We prove commutativity theorems in prime near- rings with generalized $({\sigma},{\tau})-derivation$.

• Honam Mathematical Journal
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• v.28 no.1
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• pp.69-81
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• 2006

First, we give a complete description of the multiplication modules over local Dedekind domains. Second, if R is the pullback ring of two local Dedekind domains over a common factor field then we give a complete description of separated multiplication modules over R.