• 대한화학회지
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• 제37권1호
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• pp.68-75
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• 1993

분자구조를 기술하는 molecular connectivity index, Wiener index 및 ad hoc descriptor와 알코올, 에스테르, 케톤 화합물들이 생체내에서 나타내는 enzyme inhibitory potency, lipoxygenase inhibition, tadpole narcosis potency, 증기독성(vapor toxicity), 증발열(heat of vaporization)과 같은 성질들 사이의 상관관계를 조사하였다. 생물학적 활성의 종류에 따라 molecular descriptor 사이의 우열은 있으나, 대체로 좋은 상관관계식을 얻었다.

• 한국세라믹학회지
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• 제37권3호
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• pp.240-246
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• 2000

The microwave dielectric properties of the complex perovskite (Pb0.5Ca0.5)(Fe0.5Ta0.5)O3 ceramics were investigated with the porosity and the dielectric mixing rule. Assuming that the specimens were mixtures of real dielectrics and pores, with 3-0 connectivity, the ionic polarizabilities modified by Maxwell's equation were more close to the theoretical values rather than those modified by Wiener's equation in porous specimens. The theoretical dielectirc loss were obtained with the infrared reflectivity spectra from 50 to 4000cm-1, which were calculated by Kramers-Kronig analysis and classical osciallator model. The relative tendency of dielectric loss calculated from the theoretical value and Maxwell's equation in the specimens with different porosities was in good agreement with the one by the post resonant method.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.128-132
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• 2013

L-Arginine semi-oxalate (LASO) single crystal has been grown by solution growth technique at room temperature. The crystal structure and lattice parameters were determined for the grown crystal by single crystal X-ray diffraction studies. Photoluminescence studies confirm the violet fluorescence emission peak at 395 nm. Optical constants like band gap, refractive index, reflectance, extinction coefficient and electric susceptibility were determined from UV-VIS-NIR spectrum. The dielectric constant, dielectric loss and ac conductivity of the compound were calculated at different temperatures and frequencies to analyze the electrical properties. The solid state parameters such as plasma energy, Penn gap, Fermi energy and polarizability were calculated to analyze second harmonic generation (SHG). Nonlinear optical property was discussed to confirm the SHG efficiency of the grown crystal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.422-424
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• 1996

The dielectric constants of small particles are estimated using negative dielectrophoresis(DEP). A pair of cylindrical electrodes is proposed to produce a non-uniform electric field that levitates a dielectric particle. Measuring the height of the levitated particle, we can calculate the effective polarizability, and estimate the dielectric constant of the particle using a nonlinear regression method. By determining dielectric constant of polystyrene and polychloromethylstyrene particle, the proposed electrode structure and method show the possibility to measure the dielectric constants of dielectric particles.

• KSTLE International Journal
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• 제8권2호
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• pp.21-25
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• 2007

The electrorheological effect of the suspension composed of Bismark Brown chitosan succinate as the dispersed phase in silicone oil was investigated. Bismark Brown chitosan succinate suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field. The shear stress for the suspension exhibited the dependence with a factor equals to 1.84 power on the electric field. The experimental results for the suspension correlated with the polarization model and Bismark Brown chitosan succinate suspension behaved as an anhydrous ER fluid. On the basis of the results, Bismark Brown chitosan succinate suspension showed the ER flow behavior upon application of the electric field due to the polarizability of the branched amide and amine polar groups of the Bismark brown chitosan succinate particles.

• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.106-112
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• 1994

Six physical properties (molecular weight, heat capacity, side chain weight, side chain volume, standard entropy and partial molar volume) of amino acids, peptides and their derivatives were examined by molecular modeling techniques. The molecular connectivity index, Wiener distance index and ad hoc descriptor are employed as structural parameters to encode information about branching, size, cyclization, unsaturation, heteroatom content and polarizability. This paper examines the correlation of the molecular modeling techique's parameters and the physicochemical properties of amino acids and their derivatives. As a result, calculated values were in agreement with experimental data in the above six physical properties of amino acids, peptides and their derivatives and the molecular connectivity index was superior to the other indices in fitting the calculated data.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1070-1079
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• 1994

Quantitative Structure-Activity Relationship (QSAR) studies are performed for the sets of 40 quinolones and 47 naphthyridines. Net charge, van der Waals volume, polarizability, and dipole moment are empolyed as theoretical descriptors(independent variables) to find the relationship between activity and physicochemical properties such as electrostatic effect, steric effect, and transferability. The results are analyzed by the regression and the factor analysis. It is found that for Gram-negative bacteria, the QSAR of quinolone and naphthyridine are substantially different: to describe the activity, the electrostatic effect is the most important for quinolone, and the steric effect and the transferability for naphthyridine.

• 통합자연과학논문집
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• 제5권3호
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• pp.195-197
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• 2012

Halogen atoms in a molecule are traditionally considered as electron donors, since they have unshared electrons. Normally when they are bonded, there are three lone pair electrons. These lone pairs can function as Lewis bases. However, when they are bound to electron withdrawing groups, they can act as Lewis acids. Since the situation is similar hydrogen bonding (HB), this type of interaction is named as halogen bonding (XB). This mainly comes from the uneven distribution of electron density around the halogen atoms. Since the electron density around halogen atom opposite to ${\sigma}$-bond is depleted, its electropositive region is called ${\sigma}$-hole. This ${\sigma}$-hole can attract halogen bond acceptors, requiring more stringent directionality compared to HB. Since this interaction mainly comes from electrostatic origin, the geometry tends to be linear. Since the XB energy is comparable to corresponding HB. Still in its infancy, XB shows a broad range of applicability, with potentially more useful properties, compared to corresponding HB.

• 한국안광학회지
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• 제7권2호
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• pp.27-31
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• 2002

4성분 $Li_2O-B_2O_3-Al_2O_3-SiO_2$ 유리들을 $R({\equiv}Li_2Omole%/B_2O_3mole%)$과 $K({\equiv}(Al_2O_3mole%+SiO_2mole%/B_2O_3mole%)$에 의해 제작하여 유리들의 구조를 굴절률 (refractive index)과 Vicker's 경도(hardness)의 변화를 측정하여 분석하였다. 먼저, 굴절률의 증가는 유리 내부구조의 분극률을 증가시키는 $Li^+$ 양이온 수의 증가에 우선적으로 의존하여 증가하였으며, 적은 양의 리튬 산화물($Li_2O$)이 첨가된 영역에서는 굴절률은 리튬 이온 양에 의존하며, 많은 양의 리튬 산화물이 첨가된 영역에서는 큰 몰 부피를 갖고 하나의 비가교 산소를 갖는 $BO_3{^-}$ 단위들의 형성으로 유리 구조 내의 몰 부피 증가로 유리들의 굴절률의 증가가 둔화되었다. 그리고 알루미늄 산화물($Al_2O_3$)과 규소 산화물($SiO_2$)의 증가에 따라 굴절률의 감소는 $Al_2O_3$와 $SiO_2$에 의해 형성되어진 $AlO_4$ 단위들과 $SiO_4{^-}$ 단위들이 붕소 산화물($B_2O_3$)에 의해 형성되어진 $BO_4$단위들보다 몰 부피의 증가로 감소되어졌다. 또한, 경도의 증가는 유리 망목구조에 형성되어지는 $BO_4$ 단위 수에 의존하였으며, 경도의 감소는 유리 망목구조를 개방화시키는 $BO_3{^-}$ 단위 수에 의존하여 감소함을 알 수 있었다.

• 농약과학회지
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• 제7권1호
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• pp.58-65
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• 2003

농업용 약물로서의 활용성 진단과 예측을 위한 기초 자료로서 상용화 된 제초제와 같은 분자량을 가지는 의약 각 245 종에 대한 10 가지의 물리 -화학 파라미터들을 계산하고 제초제와 광합성 (PS-II) 저해제 및 acetolactase synthase (ALS) 저해제들의 특정한 물리-화학 파라미터들에 대한 수치 범위를 비교 검토하였다. 제초제들의 특정 물리-화학 파라미터에 대한 85% 의존적 수치 범위는 소수성 상수 (Obs. logP): $-0.90\sim4.50$, 쌍극자 능율 (DM): $1.80\sim12.22$ Debye, van der Waals 분자부피 (Vol.); $558\sim995Cm^3$ 및 표면적 (S.Area): $194\sim356\;{\AA}^2$, molar refractivity (MR): $53\sim104Cm^3/mol$., 분극율 (Pol): $19\sim37\;{\AA}^3$, 분자량 : $202\sim430(amu)$, 및 수화 에너지 (Hy.E): $-10.16\sim114.7$ Kcal/mol 등 이었다. 그리고 작용 기작에 따라 물리-화학파라미터의 범위값을 특징적으로 나타내고 있음을 알았으며 MR 상수와 분극율은 의약과 제초제 (ALS 저해제)를 구분하는 판별 가능한 요소가 될 것으로 예상되었다.