• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1477-1484
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• 2007

Artificial neural networks (ANNs), for a first time, were successfully developed for the prediction partial molar heat capacity of aqueous solutions at infinite dilution for various polar aromatic compounds over wide range of temperatures (303.55-623.20 K) and pressures (0.1-30.2 MPa). Two three-layered feed forward ANNs with back-propagation of error were generated using three (the heat capacity in T = 303.55 K and P = 0.1 MPa, temperature and pressure) and six parameters (four theoretical descriptors, temperature and pressure) as inputs and its output is partial molar heat capacity at infinite dilution. It was found that properly selected and trained neural networks could fairly represent dependence of the heat capacity on the molecular descriptors, temperature and pressure. Mean percentage deviations (MPD) for prediction set by the models are 4.755 and 4.642, respectively.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1472-1476
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• 2007

Artificial neural networks (ANNs) are successfully developed for the modeling and prediction of normalized polarity parameter (ETN) of 216 various solvents with diverse chemical structures using a quantitative-structure property relationship. ANN with architecture 5-9-1 is generated using five molecular descriptors appearing in the multi-parameter linear regression (MLR) model. The most positive charge of a hydrogen atom (q+), total charge in molecule (qt), molecular volume of solvent (Vm), dipole moment (μ) and polarizability term (πI) are input descriptors and its output is ETN. It is found that properly selected and trained neural network with 192 solvents could fairly represent the dependence of normalized polarity parameter on molecular descriptors. For evaluation of the predictive power of the generated ANN, an optimized network is applied for prediction of the ETN values of 24 solvents in the prediction set, which are not used in the optimization procedure. Correlation coefficient (R) and root mean square error (RMSE) of 0.903 and 0.0887 for prediction set by MLR model should be compared with the values of 0.985 and 0.0375 by ANN model. These improvements are due to the fact that the ETN of solvents shows non-linear correlations with the molecular descriptors.

• 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.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.147-152
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• 1996

To see the quantitative relationship between the structures of the C-7 substituted quinolones and their antibacterial activities, theoretical parameters such as the molecular van der Waals volume, surface area and some electrostatic parameters based on the molecular electrostatic potential, which represent lipophilicity, and some quantum mechanical parameters are introduced as descriptors. The sixteen substituted quinolone derivatives and twenty bacteria are used for the study. It is found that the QSARs of C-7 substituted quinolones are obtained for eleven bacteria and our descriptors are more useful for Gram positive organisms than negative ones. It is also shown that molecular surface area (or molecular Waals volume) of the C-7 substituent and net charge of C-7 atom of the quinolones are the descriptors of utmost importance.

• 정보관리연구
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• 제22권2호
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• pp.1-28
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• 1991

본(本) 연구(硏究)는 한글 과학기술용어(科學技術用語)의 표준화(標準化)를 위한 기초자료를 마련하여 국내(國內) 과학기술(科學技術) 데이터베이스의 제작을 촉진하고, 또한 한글 전문용어(專門用語)와 이에 대응하는 영어(英語) 용어(用語) 및 일어(日語) 용어(用語)를 안내해 줌으로써 해외(海外) 데이터베이스 검색시(檢索時)에 편리한 검색(檢索) 툴로서 활용하는 데 목적(目的)이 있다. 과학기술분야(科學技術分野)에서 사용되고 있는 전문용어(專門用語)의 한글 용어, 영어(英語) 용어, 일어(日語) 용어 시소러스에 대한 대역(對譯) 데이터베이스를 구축한 것이다. 시소러스의 이론적인 배경을 고찰하였으며, 과학기술분야(科學技術分野) 전문용어(專門用語)의 수집은 일본과학기술정보(日本科學技術情報)센터가 1987년에 발행한 $\ulcorner$과학기술용어(科學技術用語) 시소러스 영일(英日) 리스트$\lrcorner$와 $\ulcorner$과학기술용어(科學技術用語) 시소러스 일영(日英) 리스트$\lrcorner$를 근거자료로 하여 일어(日語) 용어(用語) 및 영어(英語) 용어(用語)에 1 대(對) 1로 대응하는 한글 용어로 번역(飜譯)하였다. 과학기술용어(科學技術用語) 시소러스 대역(對譯) 데이터베이스에 수록된 한글 디스크립터는 38,318 용어, 한글 비디스크립터는 2,870용어, 영어(英語) 디스크립터는 38,318 용어, 영어(英語) 비디스크립터는 11,910 용어, 일어(日語) 디스크립터는 38,318 용어, 일어(日語) 디스크립터는 9,789 용어이다.

• Environmental Analysis Health and Toxicology
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• 제14권1_2호
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• pp.65-73
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• 1999

Dioxins refer to a family of chemicals comprising 75 polychlorinated dibenzo-p-dioxin (PCDD) and 135 polychlorinated dibenzo-p-furan (PCDF) congeners, which may cause skin disorder, human immune system disruption, birth defects, severe hormonal imbalance, and cancer. The effects of exposure of dioxin-like compounds such as PCBs are mediated by binding to the aryl hydrocarbon receptor (AHR), which is a ligand-activated transcription factor. To grasp physicochemical factors affecting human toxicity of dioxins, six geometrical and topological indices, eleven thermodynamic variables, and quantum mechanical descriptors including ESP (electrostatic potential) were analyzed using QSAR and semi-empirical AM1 method. Planar dioxins with high lipophilicity and large surface tension show the probability that negative electrostatic potential in the lateral oxygen may make hydrogen bonding with DNA bases to be a carcinogen.

• 한국군사과학기술학회지
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• 제11권3호
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• pp.154-160
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• 2008

We investigated molecular polarity by using theoretical means and comparing empirical solvent polarity. Our approach employed electrostatic potentials at the molecular surface calculated by density functional methods. A number of molecular descriptors related to molecular polarities were computed from molecular surface electrostatic potentials. Among computed molecular descriptors, the most positive electrostatic potential provided the best correlation with the empirical solvent polarities. A regression equation was developed in order to predict molecular polarities of molecules whose experimental solvent polarities were unknown. The new regression equations were utilized in estimating solvent polarities of cubane derivatives which are considered important precusors of high-energy density meterials.

• Bulletin of the Korean Chemical Society
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• 제14권5호
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• pp.631-635
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• 1993

The polarizability and the transition state energy of a cephalosporin are assumed to be theoretical indices of the permeability through the outer membrane and of reactivity of ${\beta}$ -lactam ring with penicillin binding proteins, respectively, in Gram-negative bacteria. They are computed by AM1 method and used as variables of quantitative structure-activity relationship study. The results justify quadratic dependence of the activity on the variables. The intersection of difference volumes between $\beta-lactamase$ stable cephalosporins and unstable ones manifests that the steric hindrance of 7-side chain is responsible for the ${\beta}$ -lactamase stability.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1742-1750
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• 2003

In order to characterize the hydrophobic parameters of N-acetyl amino acid amides in 1-octanol/water, a theoretical calculation was carried out using a solvation free energy density model. The hydrophobicity parameters of the molecules are obtained with the consideration of the solvation free energy over the solvent volume surrounding the solute, using a grid model. Our method can account for the solvent accessible surface area of the molecules according to conformational variations. Through a comparison of the hydrophobicity of our calculation and that of other experimental/theoretical works, the solvation free energy density model is proven to be a useful tool for the evaluation of the hydrophobicity of amino acids and peptides. In order to evaluate the solvation free energy density model as a method of calculating the activity of drugs using the hydrophobicity of its building blocks, the contracture of Bradykinin potentiating pentapeptide was also predicted from the hydrophobicity of each residue. The solvation free energy density model can be used to employ descriptors for the prediction of peptide activities in drug discovery, as well as to calculate the hydrophobicity of amino acids.

• 대한수학교육학회지:학교수학
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• 제16권3호
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• pp.519-542
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• 2014

이 연구에서는 현직 중등학교 교사 45명이 통계 영역의 수업을 분석한 결과를 검토하여 수업 실행과 관련된 교사 지식의 특징을 기술함으로써 교사의 수업 전문성 신장과 관련된 논의에 시사점을 얻고자 하였다. 이를 위해 우선 교사들의 수업 관찰 결과를 분석하기 위한 이론적 틀을 개발하고 이를 토대로 교사들이 작성한 수업 분석문의 세부 내용을 코드화하였다. 이렇게 코드화된 분석문을 통해 통계 지도와 관련된 교사 지식의 실제적 특징을 확인하여 '수업의 목적', '교사의 역할과 담화', '자료와 공학 도구'의 관점에서 통계 교육과 관련된 몇 가지 이슈를 추출하였다.