p-Nitrophenyl Picolinate의 가수분해에 대한 코발트(Ⅲ) 착물의 촉매효과

노재근,김창석,홍순영,Noh, Jae Geun,Kim, Chang Suk,Hong, Soon Yung 대한화학회 1996 대한화학회지 Vol.40 No.4

두 자리 또는 세 자리의 질소 리간드를 갖는 5종류의 코발트(III) 착물을 합성하였다. 이 착물들의 촉매 작용을 질소의 위치가 다른 세 종류의 기질, 즉 P-Nitrophenyl Picolinate, P-Nitrophenyl nicotinate, 및 P-Nitrophenyl isonicotinate의 가수분해 반응에 대하여 자외선 분광법으로 측정하였다. 이 세 가지 기질 중에서 P-Nitrophenyl Picolinate가 촉매에 가장 민감한 반응을 보였으며, 이 화합물의 가수분해 반응은 pquohydroxo형태의 착물이 가장 많이 존재하는 pH 6.5에서 이 촉매들에 의하여 21-40배 촉진 되었다. P-Nitrophenyl Picolinate의 가수분해 반응에 대한 착물의 효과는 $Co(ibpn)(OH)>Co(aepn)(OH)_2(OH_2)>Co(tn)_2(OH)(OH_2)>Co(bpy)_2(OH)(OH_2)>Co(dien)(OH)_2(OH_2)$와 같이 나타났으며 이 가수 분해 반응은 분자내 일반 염기성 촉매 반응이 우세한 과정을 따르며 부분적으로 분자내 친핵성 촉매반응 메카니즘을 따르고 있음을 알 수 있었다. Five cobalt(Ⅲ) complexes were synthesized from bi- or tridentate nitrogen ligands. Catalytic actions of these complexes for hydrolyses of p-nitrophenyl picolinate, p-nitrophenyl nicotinate, and p-nitrophenyl isonicotinate were investigated by a spectrophotometric method. p-Nitrophenyl picolinate showed the most senstive reaction among three substrates by these catalysts. Aquohydroxo Co(Ⅲ) complexes raised as much as 21∼40 times the rate of hydrolysis of p-nitrophenyl picolinate at pH 6.5. Activities of complexes were in the order: Co(ibpn)(OH)2(OH2) > Co(aepn)(OH)2(OH2) > Co(tn)2(OH)(OH2) > Co (bpy)2(OH)(OH2) > Co(dien)(OH)2(OH2). Catalytic hydrolysis was postulated to proceed through a intramolecular general base catalysis path which is mixed by a partial intramolecular nucleophilic catalysis.

Structure and Electrochemical Behavior of Aromatic Thiol Self-Assembled Monolayers on Au(111)

노재근,Hajung Park,Youngdo Jeong,Seungwook Kwon 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.3

Formation and Structure of Cyclopentanethiol Self-Assembled Monolayers on Au(111)

노재근 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.6

Nano-identification for the Cleavage of Disulfide Bond during the Self-Assembly Processes of Unsymmetric Dialkyl Disulfides on Au(111)

노재근 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.4

The formation of striped phases of unsymmetric hexyl octadecyl disulfide (CH3(CH2)5SS(CH2)17CH3, HOD) and 1-hydroxyundecyl octadecyl disulfide (CH3(CH2)17SS(CH2)11OH, HUOD) on Au(111) and graphite has been investigated by scanning tunneling microscopy (STM) to understand the self-assembly processes of dialkyl disulfides. STM imaging clearly shows the formation of striped phases having corrugation periodicities that are nearly consistent with the molecular length of alkanethiolate moieties formed after the S-S bond cleavage of dialkyl disulfide on a gold surface. On the other hand, self-assembled monolayers (SAMs) of dialkyl disulfides on a graphite surface displayed long-range, well-ordered monolayers with one striped pattern that shows periodicity as a function of molecular length via nondissociative adsorption. From a nonoscopic viewpoint, we have clearly demonstrated that dialkyl disulfide SAMs on gold form via S-S bond cleavage of disulfide.

T분기 송전선로에서의 1선 지락 고장시 고장점 표정 알고리즘

盧載根,姜相熙 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - This paper presents a fault location algorithm for a single phase-to ground fault on 3-terminal transmission systems. The method uses only the local end voltage and current signals. Other currents used for the algorithm are estimated by current distribution factor and the local end current. Negative sequence current is used to remove the effect of load current. There distance equations based on Kirchhoff's voltage law are established for the location algorithm which can be applied to a parallel transmission line having a teed circuit. Separating the real and imaginary parts of each distance equation, final nonlinear equations that are functions of the fault location can be obtained. The Newton-Raphson method is then applied to calculate the estimated fault location. Among the solutions, a correct fault distance is selected by the conditions of the existence of solution. with the results of extensive S/W and H/W simulation tests, it was verified that the proposed algorithm can estimate an accurate fault distance in a 154kV model system.

Molecular-Scale Investigation of Reconstructed Copper Surface Induced by Dissociative Adsorption of O2

노재근,정규관,박준범 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.4

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날카로운 모서리를 갖는 주상체 주위 비정상 유동 해석

노재근,김학선,이승수 한국풍공학회 2011 한국풍공학회지 Vol.15 No.2

Sectional shape with sharp edge, often applied to bridges, pose troublesome difficulties in mesh generation and numerical stability of computational fluid dynamics. Immersed Boundary Method(IBM) also experiences similar problems such as flow around triangular shape since it uses extrapolated momentum forcing inside the solid boundary in order to satisfy the no-slip on the boundary. In this paper, interpolation method is implemented into IBM in such a way that the momentum forcing is applied within the fluid domain. The developed method is applied to 2 dimensional, laminar flow around equilateral triangular shape for Re between 100 and 250, and the results are verified with previous study. Unsteady flows around various aspect ratio of isosceles triangular shape at Re=250 are simulated and the results show the reduction of mean drag and the increase of lift fluctuation. In particular, the increase of aspect ratio results in relatively large amplitude of lift with low frequency due to the reattachment of separated flow and leading vortex shedding of long period when the windward side of the triangular section is vertical to the inflow. 교량단면 등에 이용되는 날카로운 모서리를 갖는 형상 주위의 유동은 기존의 전산 유체 해석에 있어서 격자 생성이나 수치적 안정성 측면에서 매우 어려운 문제를 제기한다. 최근 많이 적용되고 있는 직교격자 기반의 가상경계법도 물체면에서 점착조건을 위해 운동량 보정을 물체 내부에 적용하는 외삽법을 이용하는데, 삼각형 단면과 같은 날카로운 모서리를 갖는 형상 주위 유동 해석에 있어 수치적 불안정성을 나타낸다. 이에 본 논문에서는 보정량이 유체 내에 작용하는 내삽법을 날카로운 모서리 형상 주위의 유동해석에 적용하였다. 개발된 방법을 이용하여 정삼각형 단면 주위의 비정상, 비압축성의 2차원 층류 유동을 해석하였으며, Re=100∼250의 유동에 대해 기존의 연구 결과와 비교를 통해 검증하였다. Re가 250의 유동장에 대해 다양한 변장비의 이등변삼각형 형상 주위의 해석 결과 변장비 증가에 따른 항력감소와 양력 변동량의 증가를 나타내었으며, 특히 풍상측이 수직인 경우 변장비 증가는 박리 유동의 재부착과 장주기의 와흘림으로 인한 저주파 대진폭의 양력 변동이 나타남을 알 수 있다.

Abnormal adsorption behavior of dimethyl disulfide on gold surfaces

노재근,장순민,Donghyung Lee,신석민,Young Joon Ko,Eisuke Ito,주상우 한국물리학회 2007 Current Applied Physics Vol.7 No.6

Adsorption of dimethyl disulde (DMDS) on gold colloidal nanoparticle surfaces has been examined to check its binding mechanism.Dierently from previous results, DMDS molecules adsorbed on the gold surface at high concentration showed the SS stretching bandat. 500 cm. 1 in surface-enhanced Raman scattering (SERS) spectra, which indicates the presence of intact adsorption of DMDS mol-iors were not observed for diethyl disulde (DEDS) or diphenyl disulde (DPDS). Our results indicate that DMDS molecules with theshortest alkyl chains on the gold surface can be inserted into self-assembled monolayers (SAMs) without the SS bond cleavage duringself-assembly due to insucient lateral van der Waals interaction and the low adsorption activity of disuldes, whereas DEDS withlonger alkyl chains or DPDS with the weak disulde bond dissociation energy would not. These unusual DMDS adsorption behaviorswere examined by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We also compared the bonding.

Structural Control and Two-Dimensional Order of Organic Thiol Self-Assembled Monolayers on Au(111)

노재근 한국진공학회 2011 한국진공학회 학술발표회초록집 Vol.40 No.0

置換 p-Nitrophenyl Benzoate類의 加水分解에 대한 Triamine-copper(Ⅱ)-imidazolate 錯化合物의 촉매 효과

홍순영,김창석,노재근 漢陽大學校 基礎科學硏究所 1995 基礎科學論文集 Vol.14 No.-

Triamine이 tridentate 리간드를 형성하는 몇 가지 triamine-copper(II)-imidazolate 착물들을 합성하여 이 착물들의 촉매 작용을 치환 p-nitrophenyl benzoate의 가수분해에 대하여 UV spectrophotometric method로 연구하였다. Triamine-copper(II)-imidazolate 착물들을 imidazole 그 자체보다 1.35-2.65배의 비교적 큰 촉매 효과를 나타내었다. 특히, triamine-copper(II)-imidazolate 착물들은 triamine이 copper(II)와 6-membered ring을 형성할 때 보다 5-membered ring을 형성할 때 촉매 효과가 더 향상되었다. 치환 p-nitrophenyl benzoate의 가수분해 반응속도는 반응 매체의 pH가 증가할 수록 또한 촉매의 농도가 커질수록 증가하였다. 치환기와 반응속도 사이에는 Hammett rule이 잘 적용되었고 전자 끄는 치환기에 의해 반응이 촉진되었다. 따라서 이 반응은 전이 상태에서 C-OR 결합 해리 보다는 물 분자의 공격에 의한 C-OH 결합 형성에 의해 지배 된다는 것을 알 수 있었다. 촉매에 의한 pH11 부근에서의 가수분해 반응에서 용매 동위원소 효과, ??, 가 2.12-3.32로 나타났으며 이 사실로부터 이들 가수분해 반응이 일반 염기성 촉매작용 메카니즘에 의해 진행 된다는 것을 알 수 있었다. Several triamine-copper(II)-imidazolate complexes in which triamine serves as a tridentate ligand were synthesized. Catalytic action of these complexes for the hydrolysis of substituted p-nitrophenyl benzoates was observed by a UV spectrophotometric method. Triamine-copper(II)-imidazolate complexes were 1.35-2.65 times more effective than imidazole itself as catalyst for the hydrolysis of p-nitrophenyl benzoate. Especially, the triamine-copper(II)-imidazolate which composed of two fused five-membered rings showed slightly more effective catalytic action than that composed of fused five-and six-membered rings or two fused six-membered rings. The hydrolysis rate of substituted p-nitrophenyl benzoates was increased with increasing pH of the reaction medium or concentration of catalyst. The rate of hydrolysis was enhanced by eletron-withdrawing substituents obeying well the Hammet rule. This implies that C-OH bond formation, rather than C-OR bond cleavage, is a rate-determining step at the transition state proceeding through a typical S?2 path. Solvent deuterium kinetic isotope effect, ??, in the hydrolysis of substituted p-nitrophenyl benzoates near pH 11, was found to be 2.12-3.32 suggesting that the catalytic hydrolysis proceeds by a general base catalysis pathway.