• 한국산림과학회지
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• 제88권4호
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• pp.429-437
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• 1999

대기오염지역에서 중금속오염의 영향을 파악하기 위해서 온산공단 주변에서 생육하고 있는 해송을 원판으로 채취하여 연륜 속의 중금속함량을 3년씩 나누어 분석하였다. 온산공단지역에서 연륜폭의 변화는 공장이 가동된 이후부터 감소하기 시작하였으며, 1991년 이후에는 급격한 감소현상이 나타나 해송의 가시적인 쇠퇴현상과 일치하였다. 온산공단지역 해송 연륜 속의 카드뮴 함량은 119.4ppb에서 867ppb로 나타났으며 1992년 이후에 급격히 증가하였다. 구리 함량은 최저 309.5ppb에서 최고 3686.8ppb로 나타났다. 납의 함량은 911.33ppb에서 7997.1ppb로 나타냈으며, 1970년 이후부터 증가하기 시작하여 공장가동 이후인 1980년 이후에는 증가폭이 컸다. 아연의 함량은 3528.7ppb에서 23826.7ppb로 나타났으며, 1960년 이후부터 큰 폭으로 상승하였고 1992년 이후에는 급 상승하는 경향이었다. 한편 비오염지역인 고성지역 해송 연륜 속의 중금속 함량은 모두 온산공단 지역보다는 많이 낮았으며, 특히 1990년 이후에는 차이가 컸다. 온산과 고성지역 해송의 수피에 축적되어 있는 중금속을 분석한 결과, 카드뮴 함량에서는 10배, 구리 함량에서는 1000배, 납 함량은 285배, 아연 함량에서는 133배의 차이를 나타내었다. 원판과 core의 분석에서는 일반적으로 core속의 중금속 함량이 높게 나타났으며, 특히 납에서는 차이가 컸다. 그러나 연륜별 증감의 패턴은 비슷한 경향을 나타내었다.

• Macromolecular Research
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• 제13권5호
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• pp.373-384
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• 2005

Novel pH-sensitive moieties containing an s-triazine ring were synthesized with sulfonamide and secondary amino groups. The synthesized pH-sensitive moieties were used for the synthesis of a pH-sensitive amphiphilic ABA triblock copolymer. The pH-sensitive triblock copolymer was composed of diblock copolymers, methoxy poly(ethylene glycol)-poly ($\varepsilon$-caprolactone-co-D,L-lactide) (MPEG-PCLA), and pH-sensitive moiety. These copolymers could be dissolved molecularly in both acidic and basic aqueous media at room temperature due to secondary amino and sulfonamide groups. The synthesized s-triazine rings containing pH-sensitive compounds were characterized by ${^1}H-NMR,\;{^13}C-NMR$, and LC/MSD spectral data. The synthesized diblock and triblock copolymers were also characterized by ${^1}H-NMR$ and GPC analyses. The critical micelle concentrations at various pH conditions were determined by fluorescence technique using pyrene as a probe. Furthermore, the micellization and demicellization study of the triblock copolymer was done with pH-sensitive groups. The sensitivity towards pH change was further established by acid-base titration.

• Journal of applied mathematics & informatics
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• 제31권3_4호
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• pp.337-342
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• 2013

In this paper, we study a special class of linear codes, called skew cyclic codes, over the ring $R=F_p+vF_p$, where $p$ is a prime number and $v^2=v$. We investigate the structural properties of skew polynomial ring $R[x,{\theta}]$ and the set $R[x,{\theta}]/(x^n-1)$. Our results show that these codes are equivalent to either cyclic codes or quasi-cyclic codes. Based on this fact, we give the enumeration of distinct skew cyclic codes over R.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.585-588
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• 2005

Bipyridine and its derivatives have been widely used as the ligands in transition metal complexes. The proton affinities of pyridine derivatives were calculated using an ab initio quantum mechanical method (B3LYP with various double zeta and triple zeta basis sets) in combination with the Poisson-Boltzmann continuum solvation model. Van der Waals radii of the atoms in the heterocyclic rings for the solvation energy calculation were set to values determined to reproduce the $pK_a$ values of guanine and oxoguanine derivatives and that of chlorine was optimized to reproduce the experimental values of relating compounds. The $pK_a$ values for the heterocyclic ring compounds were in agreement with the experimental values with a mean unsigned error of 0.45 $pK_a$ units.

• 대한수학회보
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• 제56권1호
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• pp.179-186
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• 2019

This article mainly concentrates on the open question whether a right self-injective ring R is necessary QF if $R/S_l$ is left Goldie. It is answered affirmatively under the condition $S_l{\subseteq}S_r$, where $S_l$ and $S_r$ denote the left socle and right socle of R respectively. And the original condition "right self-injective" can be weakened to "right CS and right P-injective". It is also proved that a semiperfect, left and right mininjective ring R is QF if $S_r{\subseteq}^{ess}$ $R_R$ and $R/S_l$ is left Goldie.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1629-1634
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• 2002

Reaction of tetrahomodioxa p-phenylcalix[4]arene with alkyl halide and NaH in DMF leads to the title tetra-alkylated derivatives, 7,13,21,27-tetra-phenyl-29,30,31,32-tetraalkyloxy-2,3,16,17-tetrahomo-3,17-dioxacalix [4]arenes, their preferred conformations were determined by NMR spectra as C-1,2-alternate. The molecular structure of allyl derivative has been solved by X-ray diffraction methods. The molecules have a conformation with pseudo center of symmetry. The benzene ring A is up, ring C is down, B and D rings are flat with respect to the plane of the macrocyclic ring.

• 대한수학회논문집
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• 제11권3호
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• pp.569-573
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• 1996

We study some special cases of Chow groups of a ramified complete regular local ring R of dimension n. We prove that (a) for codimension 3 Gorenstein ideal I, [I] = 0 in $A_{n-3}(R)$ and (b) for a particular class of almost complete intersection prime ideals P of height i, [P] = 0 in $A_{n-i}(R)$.

• 대한수학회논문집
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• 제14권2호
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• pp.287-293
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• 1999

In this paper, we give an affirmative answer to the question raised in [5]; whether L((P)) is principal or not. Using this fact, we try to give concrete form of module of quotient with respect to a torsion theory determined by L((P)).

• Kyungpook Mathematical Journal
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• 제28권1호
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• pp.39-44
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• 1988

In 1940, B. H. Neumann, working with a system more general than a near-field, proved that the additive group of such a system (and of a near-field) is commutative. The algebraic structure he used is known as a Neumann system (N-system). Here, the prime N-systems are classified and for each possible characteristic, examples of N-systems which are neither near-fields nor rings are given. It is also shown that a necessary condition for the set of all odd polynomials over GF(p) to be an N-system is that p is a Fermat prime.

• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.58-59
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• 1990

A method is described for the selective functionalization of calix[4]arene at the para positions of the phenyl rings. The diametrically substituted calix[4]arene dimethyl ether 3, obtained from the treatment of calix[4]arene 2 with methyl iodide in the presence of $K_2CO_3$, is converted to the diacetyloxy calix[4]arene dimethyl ether 4. This compound undergoes Fries rearrangement to yield the diametrically p-diacetylcalix[4]arene dimethyl ether 5 in 68% yield.