• 대한수학회보
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• 제22권2호
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• pp.121-126
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• 1985

D.K. Harrison [5] has shown that if R and S are fields of characteristic different from 2, then two Witt rings W(R) and W(S) are isomorphic if and only if W(R)/I(R)$^{3}$ and W(S)/I(S)$^{3}$ are isomorphic where I(R) and I(S) denote the fundamental ideals of W(R) and W(S) respectively. In [1], J.K. Arason and A. Pfister proved a corresponding result when the characteristics of R and S are 2, and, in [9], K.I. Mandelberg proved the result when R and S are commutative semi-local rings having 2 a unit. In this paper, we prove the result when R and S are 2-fold full rings. Throughout this paper, unless otherwise specified, we assume that R is a commutative ring having 2 a unit. A quadratic space (V, B, .phi.) over R is a finitely generated projective R-module V with a symmetric bilinear mapping B: V*V.rarw.R which is nondegenerate (i.e., the natural mapping V.rarw.Ho $m_{R}$ (V, R) induced by B is an isomorphism), and with a quadratic mapping .phi.:V.rarw.R such that B(x,y)=(.phi.(x+y)-.phi.(x)-.phi.(y))/2 and .phi.(rx)= $r^{2}$.phi.(x) for all x, y in V and r in R. We denote the group of multiplicative units of R by U(R). If (V, B, .phi.) is a free rank n quadratic space over R with an orthogonal basis { $x_{1}$, .., $x_{n}$}, we will write < $a_{1}$,.., $a_{n}$> for (V, B, .phi.) where the $a_{i}$=.phi.( $x_{i}$) are in U(R), and denote the space by the table [ $a_{ij}$ ] where $a_{ij}$ =B( $x_{i}$, $x_{j}$). In the case n=2 and B( $x_{1}$, $x_{2}$)=1/2, we reserve the notation [ $a_{11}$, $a_{22}$] for the space.the space.e.e.e.

• 한국가스학회지
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• 제17권1호
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• pp.73-80
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• 2013

본 연구에서는 유한요소해석법을 사용하여 V홈 오링의 밀봉거동과 내구 안전성에 관련된 변형률, 응력, 접촉법선응력 해석결과를 제시하고 있다. 밀봉거동과 내구 안전성에 관한 FEM 해석결과에 의하면, V홈 형상을 갖는 오링에 작용하는 최대변형률, 최대압축응력, 최대접촉법선응력은 기존의 오링에 비해 약 1.2배나 더 높게 나타났다. 이것은 오링이 두 개의 원형을 겹치도록 형성된 중간부에 V홈을 넣었기 때문에 가능한 것으로 판단되고, V홈 오링은 볼밸브, 압력용기, 가스기기의 밀봉을 하는데 매우 유용한 것으로 알려져 있다. 그리고, V홈 오링에서 가스압력을 높여도 압출에 의한 파손현상이 발생되지 않았는데, 이것은 V홈이 형성되어 있기 때문이다. 따라서, V홈 오링은 기존 오링에 비해 밀봉수명을 연장시킬 수 있다.

• 대한수학회지
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• 제45권3호
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• pp.727-740
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• 2008

A ring R is called IFP, due to Bell, if ab=0 implies aRb=0 for $a,b{\in}R$. Huh et al. showed that the IFP condition need not be preserved by polynomial ring extensions. But it is shown that ${\sum}^n_{i=0}$ $E_{ai}E$ is a nonzero nilpotent ideal of E whenever R is an IFP ring and $0{\neq}f{\in}F$ is nilpotent, where E is a polynomial ring over R, F is a polynomial ring over E, and $a_i^{'s}$ are the coefficients of f. we shall use the term near IFP to denote such a ring as having place near at the IFPness. In the present note the structures of IFP rings and near-IFP rings are observed, extending the classes of them. IFP rings are NI (i.e., nilpotent elements form an ideal). It is shown that the near-IFPness and the NIness are distinct each other, and the relations among them and related conditions are examined.

• 한국운동역학회지
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• 제16권3호
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• pp.173-181
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• 2006

The purpose of this study is grasp the problem of the gymnast, Kim, Dong-Hwa's Kip to Swallow Motion in Rings, and make up for the weak points to help him to perform a better performance. Therefore, two tryouts for $28^{th}$ Athens Olympic Games were filmed using video camera then finalized with Kinematical Analysis using 3D motion analysis program followings are the form of conclusions. 1. In the very first tryout, when he was doing a Swallow Support Scale, his CM position was high and arm slope was deduction because when he was doing Kip, the ascent velocity was low and he tried excessively to pull him on rings due to relying upon angular movement of shoulder joint. 2. When he was doing drop, he let his hip angle bend only little bit and let fall so making shoulder angle wider and maintain the level horizontally occurs strong drop motion when vertical descent is happening. 3. As a result, lowering the direction of a kick makes CM's movement path lower, increase vertical ascent velocity, and it helps to do the Swallow Support motion in short period of time. 4. After a strong drop motion, which is deep and fast, would make rope of ring shake so there is a defect that the body moves to forward area. However, it does not effect in Swallow Support Scale motion. 5. In the second tryout, trunk rotation angle and arm slope was fixed decrease while doing rotary motion. When rotary motion was happening, before the body was going under the rings, maintained his arm slope horizontally so his Swallow Support Scale motion was nearly perfect.

• Advances in Traditional Medicine
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• 제2권2호
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• pp.87-93
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• 2002

The present study was aimed to examine the role of endothelium in the relaxant effect of hawthorn fruit extract of Crataegus pinnatifida in four different types of rat arteries, posterior cerebral communicating artery, right descending coronary artery, common carotid artery, and aorta. In $9,11-dideoxy-11{\alpha}$, $9{\alpha}-epoxy-methanoprostaglandin$ $F_{2{\alpha}}$ (U46619)-preconstricted arterial rings except for aorta, the extract produced endothelium-independent relaxations with similar potency. This relaxation was unaffected by pretreatment with $100\;{\mu}M\;N^G-nitro-L-arginine$ methylester (L-NAME, the nitric oxide synthase inhibitor), $3\;{\mu}M$ 1H-[l,2,4]oxadiazolo$[4,2-{\alpha}]$quinoxalin-1-one (ODQ, the guanylate cyclase inhibitor), or $10\;{\mu}M$ indomethacin (the cyclooxygenase inhibitor). Putative $K^+$ channel blockers (charybdotoxin plus apamin or glibenclamide) did not affect the extract-induced relaxation in cerebral or coronary artery rings. In contrast, in rat aortic rings the extract produced significantly smaller relaxant response in endothelium-denuded rings than that in endothelium-intact rings. Pretreatment with L-NAME or ODQ abolished the extractinduced endothelium-dependent aortic relaxation, whilst indomethacin $(3\;{\mu}M)$ had no effect. The present results indicate that hawthorn fruit extract possesses a vasorelaxing effect in cerebral, coronary and carotid arteries and this effect is independent of the presence of a functional endothelium. However, the extract-induced endothelium-dependent relaxation in rat aorta was mediated through endothelial nitric oxide and cyclic GMP-dependent mechanisms, suggesting that active components in the extract may act on endothelium to stimulate release of nitric oxide in large conduit arteries of the rats.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1993년도 학술대회지
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• pp.40-48
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• 1993

Intravenous administration of saponin extracted from the root of Panax ginseng lowered the blood pressure dose-dependently (10-200 mg/kg, B.W) in anesthetized rats. Therefore, experiments were designed to study the hypothesis that the lowering of blood pressure is associated with the release of endothelium-derived relaxing factor and the accumulation of guanosine 3, 5-cyclic monophosphate (cGMP). Rings of thoracic aorta with and without endothelium were suspended for the measurement of isometric tension in organ chamber and the tissue content of cGMP was measured by radioimmunoassay. All experiments were performed in the presence of $indomethacin(10^{-5}M).$ Ginseng saponin $(10^{-5}-3{\times}10^{-6}g/ml)$ relaxed contractions induced by phenylephrine $10^{-6}M)$ in the aorta with endothelium but not in that without endothelium. Treatment of aortic rings with $N^G$ monomethyl-L-arginine (L-NMMA, $10^{-4}M$ for 30 min), a competitive inhibitor of nitric oxide synthase, and methylene blue $(MB,\;3{\times}10^{-7}M$ for 30 min). an inhibitor of soluble guanylate cyclase, diminished the relaxation induced by Ginseng saponin. Ginseng saponin $10^{-4}g/ml$ for 2 min) increased the accumulation of cGMP in rings with endothelium. L-NMMA and MB inhibited the accumulation of cGMP induced by Ginseng saponin. These data suggest that vascular relaxations induced by Ginseng saponin are mediated by release of endothelium-derived relaxing factor and the accumulation of cGMP. The effect of Ginseng saponin on endothelial function in hypercholesterolemic rabbits was examined. In hypercholesterolemic rabbits fed with $2\%$ cholesterol for 8 weeks, relaxation of aortic rings to acetylcholine was impaired. The impaired relaxations of aortic rings in hypercholesterolemic rabbits were improved by dietary supplementation of Ginseng saponin, probably because of an improved release of endothelium - derived relaxing factor.

• 생약학회지
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• 제17권2호
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• pp.178-183
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• 1986

It was our working hypothesis that introduction of 11-keto groups to 12-oleanene/ursene series of triterpenoids should endow them with corticoid-like activities, since pharmacological actions of glycyrrhetinic acid (GA) are known to be caused by inhibition on $corticoid-{\delta}^4-reductase$. 11-Keto-triterpenoids derived artificially in these studies, such as 11, 19-diketo-18, 19-secoursolic acid methyl ester(I), $11-keto-{\beta}-boswellic$ acid derivatives (IIa-IIc), 11-Keto-presenegenin dimethyl ester (III), II-keto-oleanolic acid derivatives (IVa-IVd) and 11-keto-hederagenin (V) possess the fundamental functions of ${\alpha},\;{\beta}-unsaturated$ ketone on C-11 and hydroxyl group on C-3, as like GA (VI). Additionally, they involve the carboxyl groups on rings A (II, III), D (I, III, IV, V) and E (VI), and the hydroxyl groups on rings A (III, V) and C (III). All the compounds competitively inhibited $corticoid-5{\beta}-reductase$, and the highest inhibitory potency appeared in I. All of them except $3,\;11-diketo-{\beta}-boswellic$ acid methyl ester (IIc) were more effective about five times to twice than GA. On carrageenin-induced edema test, compounds I and IVa-IVd showed anti-inflammatory activities, but III enhanced rather edema. Structure-activity relations were found in the aspects of hydrophilicity of ring A and hydrophobicity of rings C/D. The more they were hydrophilic in ring A and hydrophobic in rings C/D, the more they inhibited the enzyme. And the more they were hydrophobic in rings C/D, the more they exhibited antiiflammatory activities. However, the increased hydrophilicity in ring A resulted in increasing edema, probably due to a nonspecific inhibition on $aldosterone-5{\beta}-reductase$.

• 대한수의학회지
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• 제45권4호
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• pp.553-562
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• 2005

Melatonin, the principal hormone of the vertebral pineal gland, participates in the regulation of cardiovascular system in vitro and in vivo. Lithium inhibits both inositol polyphosphate phosphatase (IPPase) and inositol monophosphatase (IMPase), which are involved in a wide range of signal transduction pathways. The aim of the present study was to assess the effect of lithium on endothelial-dependent relaxation to melatonin and on the melatonin-induced inhibition of contraction by phenylephrine (PE) in isolated rat aorta. Melatonin induced a concentration-dependent relaxation in PE-precontracted in endothelium-intact (+E) aortic rings. Melatonin inhibited a PE-induced sustained contraction in +E aortic rings. These effects of melatonin on relaxation and contractile responses were inhibited by pretreatment with lithium. In PE-precontracted +E aortic rings, the melatonin-induced vasorelaxations and the inhibitory effects of melatonin on maximal contractions were inhibited by endothelium removal or by pretreatment with L-$N^G$-nitro-arginine (L-NNA), 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ) and nifedipine and verapamil, but not by tetrabutylammonium, clotrimazole and glibenclamide, However, in endothelium-denuded (-E) aortic rings and in the presence of L-NNA and ODQ in +E aortic rings, the melatonin-induced residual relaxations and the melatonin-induced residual contractile responses to PE were not affected by lithium. It is concluded that the inositol phosphate pathway may be involved in endothelial-dependent relaxation induced by melatonin.

• 대한수의학회지
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• 제45권4호
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• pp.507-515
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• 2005

Melatonin, the principal hormone of the vertebral pineal gland, participates in the regulation of cardiovascular system in vitro and in vivo. However, the effects of melatonin on vascular tissues are still vague. The aim of this study was to assess the relationship between phospholipase C (PLC) and nitric oxide synthase (NOS)/cyclic guanosine 3',5'-monophosphate (cGMP) signaling cascade in the relaxatory action of melatonin in isolated rat aorta. Melatonin induced a concentration-dependent relaxation in phenylephrine (PE)- and KCl-precontracted endothelium intact (+E) aortic rings. In KCl-precontracted +E aortic rings, the melatonin-induced vasorelaxation was not inhibited by endothelium removal or by pretreatment with NOS inhibitors, L-$N^G$-nitor-arginine (L-NNA) and L-$N^G$-nitor-arginine methyl ester (L-NAME), guanylate cyclase (GC) inhibitors, methylene blue (MB) and 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ). In PE-precontracted +E aortic rings, the melatonin-induced vasorelaxation was inhibited by endothelium removal or by pretreatment with L-NNA, L-NAME, MB, ODQ and 2-nitro-4-carboxyphenyl-n,n-diphenylcarbamate (NCDC). Moreover, in without endothelium (-E) aortic rings and in the presence of L-NNA, L-NAME, MB and ODQ in +E aortic rings, the melatonin-induced residual relaxations and residual contractile responses to PE were not affected by NCDC, a PLC inhibitor. It is concluded that melatonin can evoke vasorelaxation due to inhibition of PLC pathway through the protein kinase G activation of endothelial NOS/cGMP signaling cascade.

• 한국진공학회지
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• 제8권1호
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• pp.43-50
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• 1999

이온빔보조증착법으로 h-BN을 증착하여 이온에너지 및 기판온도에 따른 hexagonal ring의 배열 및 결정성의 변화를 연구하였다. 보론은 전자빔으로 1.5 $\AA$/sec 의 속도로 증발시켰으며, 질소는 둥-hall 형 이온건으로 60, 80, 100eV의 에너지로 공급하였다. 기판의 온도는 상온(no heating), 200, 400, 500, $800^{\circ}C$로 변화시켰다. 질소이온에너지가 증가할수록 hexagonal ring의 c축은 기판에 평행하게 배열하여 100 eV의 질소이온에너지에서 가장 좋은 배열을 나타내었다. 이는 이온에너지가 높을수록 합성 막에 큰 압축응력이 발생하기 때문으로 생각된다. 기판온도에 따라서는 온도가 증가함에 따라 배열이 증가하다가 약 $400^{\circ}C$에서 최대가 되고 그 보다 높은 온도에서는 배열이 감소하였다. 그리고 결정도는 온도가 증가할수록 향상되었다. 이러한 경향들은 온도가 증가함에 따라 원자 이동도는 증가하고 응력발생은 어려워지는 경향으로부터 잘 설명된다. 또한 nano-indentor로 측정한 h-BN막의 경도는 c-축의 배열정도와 같은 경향을 보였다. 이온빔보조증착법은 hexagonal ring의 배열을 통해 h-BN막 성질의 최적화에 효과적인 방법으로 판단된다.