• 제목/요약/키워드: NI ring

검색결과 96건 처리시간 0.068초

서울시 가로수의 연륜층 및 식재주변 토양의 증금속 농도와 연륜 생장 (Heavy Metal Concentrations in Tree Ring Layer and Soil and Tree Ring Growth of Roadside Trees in Seoul)

  • 유재윤;손요환
    • 한국환경농학회지
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    • 제22권2호
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    • pp.118-123
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    • 2003
  • 본 연구는 서울 도심에 위치한 가로수 중에서 수령이 30년 이상 된 양버즘나무(Platanus occidentalis L.)와 은행나무(Ginkgo biloba L.)를 대상으로 토양 및 가로수의 연륜층별로 중금속 농도를 분석하여 이들 중금속이 가로수의 연륜 생장에 미치는 영향 정도를 비교 검토하였다. 가로수가 식재되어 있는 토양의 pH는 $6.62{\sim}8.01$이었으며, 중금속 평균농도는 Cr 0.63, Zn 109.03, Pb 26.49, Ni 1.98, Cu 44.98 mg/kg으로써 이 중 Zn, Pb, Cu의 농도는 일반 산림토양보다 높은 것으로 나타났다. 특히 금속 및 철물을 취급하는 상가가 밀집해 있고 차량통행이 많은 청계 2가 지역의 중금속 농토가 가장 높게 나타났다. 가로수의 연륜폭을 1979년부터 2000년까지 측정하여 회귀식으로 나타낸 결과, 두 수종 모두 감소하는 경향을 보였다. 또한, 토양 내 Cr, Pb, Cu의 농도는 양버즘나무의 최근 5년간 연륜층 내 Cr, Pb, Cu 농도와 양의 상관관계를 보였으며, 토양 내 Ni 농도는 은행나무의 연륜층 내 Ni 농도와 양의 상관관계를 보였다. 양버즘나무의 5년 단위 연륜층별 Cr 농도와 은행나무의 5년 단위 연륜층별 Ni, Cu 농도는 각각 연륜생장에 음의 상관관계를 나타냈다. 한편 서울지역의 연평균 기온, 강수량, 강수일수와 연륜폭의 연도별 변화 경향은 유사하였으나 통계적으로 유의성은 인정되지 않았다.

The Relation Between Units and Nilpotents

  • Cheon, Jeoung Soo;Kwak, Tai Keun;Lee, Yang;Seo, Young Joo
    • Kyungpook Mathematical Journal
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    • 제62권2호
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    • pp.213-227
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    • 2022
  • We discuss the relation between units and nilpotents of a ring, concentrating on the transitivity of units on nilpotents under regular group actions. We first prove that for a ring R, if U(R) is right transitive on N(R), then Köthe's conjecture holds for R, where U(R) and N(R) are the group of all units and the set of all nilpotents in R, respectively. A ring is called right UN-transitive if it satisfies this transitivity, as a generalization, a ring is called unilpotent-IFP if aU(R) ⊆ N(R) for all a ∈ N(R). We study the structures of right UN-transitive and unilpotent-IFP rings in relation to radicals, NI rings, unit-IFP rings, matrix rings and polynomial rings.

FURTHER STUDY OF RINGS IN WHICH ESSENTIAL MAXIMAL RIGHT IDEALS ARE GP-INJECTIVE

  • SANGBOK NAM;TAEHEE LEE;HWAJOON KIM
    • Journal of applied mathematics & informatics
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    • 제41권6호
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    • pp.1173-1180
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    • 2023
  • In this paper, rings in which essential maximal right ideals are GP-injective are studied. Whether the rings with this condition satisfy von Neumann regularity is the goal of this study. The obtained research results are twofold: First, it was shown that this regularity holds even when the reduced ring is replaced with π-IFP and NI-ring. Second, it was shown that this regularity also holds even when the maximal right ideal is changed to GW-ideal. This can be interpreted as an extension of the existing results.

디젤엔진용 소결(W/C35%Ni) 태핏의 마멸거동에 관한 연구 (A Study on Friction and Wear Characteristics of Sintered W/C-35%Ni Tappets for Diesel Engine Application)

  • 류병진;오세일;박맹로;양승호
    • Tribology and Lubricants
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    • 제16권1호
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    • pp.33-38
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    • 2000
  • Abstract- In this paper tribological characteristics of solid and liquid phase sintered W/C-35%Ni tappets were investigated. Three test methods were performed to investigate the wear and surface damage mechanism of sintered tappets. First, block-on-ring wear test was performed to investigate the wear characteristics under pure sliding condition. Second, simplified cam and tappet tests (called component wear test hereafter) were carried out to simulate the real contact history of cam and tappet. Also, after the test, contact surfaces were analyzed with scanning electron microscope to study the wear mechanism. As a final screening, engine dynamo tests were performed. Results showed that in the block on ring sliding wear test, solid phase sintered specimens showed superior wear resistance to liquid phase sintered specimens. The component wear tests and engine dynamo tests also showed the same results. Therefore, in these tests, solid phase sintered tappet material revealed superior wear resistant properties to liquid phase sintered one.

Synthesis and Electrochemical Studies of Ni(Ⅱ) Complexes with Tetradentate Schiff Base Ligands

  • 정병구;임채평;국성근;조기형;최용국
    • Bulletin of the Korean Chemical Society
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    • 제17권2호
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    • pp.173-179
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    • 1996
  • A series of tetradentate Schiff base ligands; [1,2-bis(naphthylideneimino)ethane, 1,3-bis(naphthylideneimino)propane, 1,4-bis(naphthylideneimino)butane, and 1,5-bis(naphthylideneimino)pentane] and their Ni(Ⅱ) complexes have been synthesized. The properties of these ligands and their Ni(Ⅱ) complexes have been characterized by elemental analysis, IR, NMR, UV-vis spectra, molar conductance, and thermogravimetric analysis. The mole ratio of Schiff base to Ni(Ⅱ) metal was found to be 1:1. The electrochemical redox process of the ligands and their Ni(Ⅱ) complexes in DMF and DMSO solution containing 0.1 M tetraethyl ammonium perchlorate (TEAP) as a supporting electrolyte have been investigated by cyclic voltammetry, chronoamperometry, differential pulse voltammetry, and controlled potential coulometry at glassy carbon electrode. The redox process of the ligands was highly irreversible, whereas redox process of Ni(Ⅱ) complexes were observed as one electron transfer process in quasi-reversible and diffusion-controlled reaction. The electrochemical redox potentials of the Ni(Ⅱ) complexes were affected by the chelate ring size of ligands. The diffusion coefficients of Ni(Ⅱ) complexes containing 0.1 M TEAP in DMSO solution were determined to be 5.7-6.9 × 10-6 cm2/sec. Also the exchange rate constants were determined to be 1.8-9.5 × 10-2 cm2/sec. These values were affected by the chelate ring size of ligands.

IFP RINGS AND NEAR-IFP RINGS

  • Ham, Kyung-Yuen;Jeon, Young-Cheol;Kang, Jin-Woo;Kim, Nam-Kyun;Lee, Won-Jae;Lee, Yang;Ryu, Sung-Ju;Yang, Hae-Hun
    • 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.

재생냉각 연소기의 냉각기구에 따른 특성 파악 (Investigation of Characteristics for Cooling Parameters of a Combustor in Liquid Rocket Combustors)

  • 김홍집;최환석
    • 한국추진공학회지
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    • 제14권5호
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    • pp.45-50
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    • 2010
  • 연료링의 위치 및 열차폐 코팅의 종류에 따른 연소기의 재생냉각 특성을 검토하였다. 연료링을 노즐의 중간 부분에 위치시키고 냉각채널을 분기시켜서 설계하는 방법이 열적으로 타당함을 확인하였다. 또한 복합재를 이용한 노즐확장부가 적용 가능한 기술적 상황이라면, 팽창비가 높고 열유속이 낮은 노즐 후류 부분은 이를 이용하는 것이 매우 적절하다고 판단된다. 적용 가능한 열차폐 코팅 중에서 30톤급 연소기 및 가스발생기 개발과정에서 사용했던 $Y_2O_3$ stabilized $ZrO_2$과 내산화성이 우수한 Ni/Cr을 고려하였다. 내산화성이 우수한 Ni/Cr에 비해 세라믹 코팅($Y_2O_3$ stabilized $ZrO_2$)이 열차폐 효과가 우수한 것으로 파악되었다.

재생냉각 연소기의 냉각기구에 따른 냉각 특성 파악 (Regenerative Cooling Characteristics for Cooling Parameters of a Combustor in Liquid Rocket Combustors)

  • 김홍집;최환석
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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    • pp.145-149
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    • 2010
  • 연료링의 위치 및 열차폐 코팅의 종류에 따른 연소기의 재생냉각 특성을 검토하였다. 연료링을 노즐의 중간 부분에 위치시키고 냉각채널을 분기시켜서 설계하는 방법이 열적으로 타당함을 확인하였다. 또한 복합재를 이용한 노즐확장부가 적용 가능한 기술적 상황이라면, 팽창비가 높고 열유속이 낮은 노즐 후류 부분은 이를 이용하는 것이 매우 적절하다고 판단된다. 적용 가능한 열차폐 코팅 중에서 30톤급 연소기 및 가스발생기 개발과정에서 사용했던 $Y_2O_3$ stabilized $ZrO_2$과 내산화성이 우수한 Ni/Cr을 고려하였다. 내산화성이 우수한 Ni/Cr에 비해 세라믹 코팅($Y_2O_3$ stabilized $ZrO_2$)이 열차폐 효과가 우수한 것으로 파악되었다.

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REVERSIBILITY OVER PRIME RADICALS

  • Jung, Da Woon;Lee, Yang;Sung, Hyo Jin
    • Korean Journal of Mathematics
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    • 제22권2호
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    • pp.279-288
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    • 2014
  • The studies of reversible and 2-primal rings have done important roles in noncommutative ring theory. We in this note introduce the concept of quasi-reversible-over-prime-radical (simply, QRPR) as a generalization of the 2-primal ring property. A ring is called QRPR if ab = 0 for $a,b{\in}R$ implies that ab is contained in the prime radical. In this note we study the structure of QRPR rings and examine the QRPR property of several kinds of ring extensions which have roles in noncommutative ring theory.

Synthesis and Characterization of New Polyaza Non-macrocyclic and Macrocyclic Nickel(II) Complexes Containing One 1,3-Diazacyclohexane Ring

  • Lee, Yun-Taek;Jang, Bo Woo;Kang, Shin-Geol
    • Bulletin of the Korean Chemical Society
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    • 제34권7호
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    • pp.2125-2130
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    • 2013
  • A new nickel(II) complex $[NiL^1]^{2+}$ ($L^1$ = 1-(2-aminoethyl)-3-(N-{2-aminoethyl}aminomethyl-1,3-diazacyclohexane) containing one 1,3-diazacyclohexane ring has been prepared selectively by the metal-template condensation of formaldehyde with N-(2-aminoethyl)-1,3-propanediamine and ethylenediamine at room temperature. The complex reacts with nitroethane and formaldehyde to yield the pentaaza macrocyclic complex $[NiL^2]^{2+}$ ($L^2$ = 8-methyl-8-nitro-1,3,6,10,13-pentaazabicyclo[13.3.1]heptadecane) bearing one C-$NO_2$ pendant arm. The reduction of $[NiL^2]^{2+}$ by using Zn/HCl produces $[NiL^3(H_2O)]^{2+}$ ($L^3$ = 8-amino-8-methyl-1,3,6,10,13-pentaazabicyclo[13.3.1]heptadecane) bearing one coordinated C-$NH_2$ pendant arm that is readily protonated in acid solutions. The hexaaza macrocyclic complex $[NiL^4]^{2+}$ ($L^4$ = 8-phenylmethyl-8-nitro-1,3,6,8,10,13-hexaazabicyclo[13.3.1]heptadecane) bearing one N-$CH_2C_6H_5$ pendant arm has also been prepared by the reaction of $[NiL^1]^{2+}$ with benzylamine and formaldehyde. The nickel(II) complexes of $L^1$, $L^2$, and $L^4$ have square-planar coordination geometry in the solid states and in nitromethane. However, they exist as equilibrium mixtures of the square-planar $[NiL]^{2+}$ (L = $L^1$, $L^2$, or $L^4$) and octahedral $[NiL(S)_2]^{2+}$ species in various coordinating solvents (S); the proportion of the octahedral species $[NiL(S)_2]^{2+}$ is strongly influenced by the ligand structure and the nature of the solvent. Synthesis, spectra, and chemical properties of the nickel(II) complexes of $L^1-L^4$ are described.