• 약학회지
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• 제33권6호
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• pp.350-360
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• 1989

The conformation and activity of the four benzenesulfonyl analogues of 4-aminobenzene-sulfonamide, 4-aminobenzenesulfonic acid, 4-methylbenzenesulfonamide, and 4-methylbenzenesulfonic acid with antibacterial activity on Staphylococcus aureus were studied using an empirical potential function (ECEPP/2) and the hydration shell model. The conformational energies were minimized from the starting conformations which included possible combinations of torsion angles in each molecule. To understand the hydration effect on the conformation of the molecule in aqueous solution, the hydration free energy of each group was calculated and compared each other. The conformational entropies of low-free-energy coformation of benzenesulfonly analogues were computed by a harmonic approximation. From the correlation of lowest-free-energy conformation of each compound and its antibacterial activity, it was found that the hydration of sulfonyl groups and the substituents are the decisive factors to show antibacterial activities.

• 약학회지
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• 제39권3호
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• pp.329-336
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• 1995

Conformational free energy calculations using an empirical potential function and a hydration shell model(program CONBIO) were carried out on hypoglycemic agent acetohexamide and tolazamide in the unhydrated and hydrated states. The initial geometry of sulfonylureas was obtained from X-ray crystallographieal data and homologous molecular fragments. In both states, the feasible conformations were obtained from the calculations of conformational energy, conformational entropy, and hydration free energy by varying all the torsion angles of the molecules. From the calculation results, it is known that the conformations] entropy is the major contribution to stabflize the low-free-energy conformations of two sulfonylureas in both states. But, in hydrated state, the hydration does not directly affect each conformations. The intramolecular hydrogen bonding of sulfonylurea hydrogen and 7-membered nitrogen appeared to the conformations of tolazamide in both states. It is thought that the hydrogen bonding decrease steric hindrance on the receptor binding direction. The substitution of alicyclic or N-heterocyclic ring than that of carbons chain of urea moiety may be properly interaction between sulfonylureas and the putative pancreatic receptor.

• Bulletin of the Korean Chemical Society
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• 제4권3호
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• pp.133-139
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• 1983

To understand the importance of Y-base adjacent to the anticodon stabilizing codon-anticodon interaction, a study has been undertaken for the model compound involving the interaction between Y-base and anticodon as well as the participation of water molecule by calculating the conformational free energy using an empirical potential function. We restrict our analysis to sites directly associated with Y-base by varying only the backbone torsion angles of Y-base. The hydration and $Mg^{+2}$ binding effects on the conformational stability of Y-base are calculated and discussed. The free Y-base is proved to be less stable than the hydrated one. The free energy change due to the hydration of Y-base amounts to -119.5 kcal/mole, in which the conformational energy change is -142.4 kcal/mole and the configurational entropy change is -76.9 e. u. It is found that the water molecules bound to Y-base and $Mg^{+2}$ contribute to the conformation of Y-base dominantly.

• 충청수학회지
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• 제30권2호
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• pp.251-258
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• 2017

The aim of the present paper is to establish some results involving generalized ${\ast}$-derivations in ${\ast}$-rings and investigate the commutativity of prime ${\ast}$-rings admitting generalized ${\ast}$-derivations of R satisfying certain identities and some related results have also been discussed.

• 전기의세계
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• 제32권3호
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• pp.142-149
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• 1983

지금까지 알려진 내부마찰측정방법으로는 자유감쇄법(free decay method), 강제진동법(forced vibration method), 비공진강제진동법(non-resonance forced vibration method) 및 초음파법(ultrasoni method) 등이 있다. 이상의 모든 내부마찰실험방법에 관한 실험장치는 그 기계의 동작특성에 따라 실험주파수가 극히 한정되어 있어 연속적인 변화를 시킬 수 없으므로 완화효과를 연속적으로 추적하기 위하여 온도를 변화시키는 방법이 널리 사용되고 있다. 이상에서 소개한 방법들중 본인들이 국산제작실험에 성공한 바 있는 장치는 자유감쇄법에 속하는 염회진자장치(torsion pendulum device) 이므로 이 장치를 중심으로 내부마찰측정원리와 그의 장치에 관하여 소개하고저 한다.

• 대한수학회보
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• 제35권2호
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• pp.259-268
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• 1998

We give several characterizations of a TV-PVMD and we show that the localization R[X;S]$_{N_{\upsilon}}$ of a semigroup ring R[X;S] is a TV-PVMD if and only if R is a TV-PVMD where $N_{\upsilon}\;=\;\{f\;{\in}\;R[X]{\mid}(A_f)_{\upsilon} = R\}$ and S is a torsion free cancellative semigroup with zero.

• Korean Journal of Mathematics
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• 제17권3호
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• pp.233-236
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• 2009

We investigate in this paper some equivalent conditions for right principally quasi-Baer rings to be reflexive. Using these results we are able to prove that if R is a reflexive right principally quasi-Baer ring then R is a left principally quasi-Baer ring. In addition, for an idempotent reflexive principally quasi-Baer ring R we show that R is prime if and only if R is torsion free.

• 대한수학회보
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• 제45권2호
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• pp.253-261
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• 2008

In this paper, we introduce the notion of generalized left derivation on a ring R and prow that every generalized Jordan left derivation on a 2-torsion free primp ring is a generalized left derivation on R. Some related results are also obtained.

• 대한수학회보
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• 제51권1호
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• pp.207-211
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• 2014

The aim of this paper is to prove the next result. Let n > 1 be an integer and let R be a n!-torsion free semiprime ring. Suppose that f : R ${\rightarrow}$ R is an additive mapping satisfying the relation [f(x), $x^n$] = 0 for all $x{\in}R$. Then f is commuting on R.

• 대한수학회보
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• 제50권4호
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• pp.1297-1302
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• 2013

We prove that the mapping class group of a non-Haken orientable irreducible 3-manifold is finite and we show that the quotient group of the mapping class group by the rotation group is virtually torsion-free if the manifold does not have 2-sphere boundary components.