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BaTiO3 의 유전특성에 대한 Nb5+ 이온의 첨가효과
황인철,주웅길,이문호 한국화학공학회 1979 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.17 No.5
BaTiO₃의 소결밀도 및 유전특성에 소결온도와 Nb^(5+) 이온의 첨가가 미치는 영향을 고찰하였다. BaTiO₃의 유전상수 및 그 온도 특성은 Nb^(5+) 이온의 첨가량, 소결온도, 소결후 냉각속도에 따라서 변하였다. 이 결과는 grain size 및 내부응력과 밀접한 관련이 있다고 판단되며, 내부응력모델과 일치하였다. 약 0.5mole% 이하의 Nb^(5+) 이온을 첨가하였을 때는 소결능이 감소하는 경향을 나타냈으나, 그 이상을 첨가하였을 때는 소결능이 증가하였다. The effect of sintering temperature and Nb^(5+) ion addition on the sintered density and the dielectric properties of BaTiO₃ has been investigated. The dielectric constant and its temperature dependence of BaTiO₃ varied with the concentration of the Nb^(5+) ion, the sintering temperature, and the cooling rate after the sintering. Their variation was intimately related with the grain size and the internal stress, which coincided with the internal stress model. Below the concentration of about 0.5 mole% Nb^(5+) ion the sinterability was reduced, butt above that concentration it was raised.
Molecular Orbital Studies on the Carcinogenicity of Polycyclic Aromatic Hydrocarbons
황인철 高神大學校 1988 論文集 Vol.16 No.-
The carcinogenicity of PAH (Polycyclic Aromatic Hydrocarbon) was studies with the molecular orbital method in this paper. The theoretical calculations of molecular orbitals are based on the simple Huckel method. The model of carcinogenicity of PAH was followed by the “bay region” model. This model shows that K region binds with enzymes, and that epoxidations occur A and B region. As reactivity indices, frontier electron density, suberdelocalizability and approximate superdelocalizability are calculated. Thirty―nine compounds were tested in this paper. The results are as follows : 1. The frontier electron density and approximate superdelocalizability and not show good correlations with carcinogenicity of PAH in this paper. 2. A to B ratios of the approximate superdelocalizability were located between values of 0.9960 and 1.0070 in carcinogenic compounds. (K + A + B) values of carcinogenic compounds were generally larger than 5.7000. 3. Theoretically, it is not easy to estimate the strength of carcinogenicity. However, the superdelocalizability of (K + A + B) region gives a good correlation with the carcinogenicity of PAH studied. Therefore, K, A, and B region of those compounds are all related to the carcinogenicity.
Application of the Extended Huckel Method to the CO Molecule on Cu Cluster
黃仁哲 高神大學校 1990 論文集 Vol.18 No.2
To theoretically interpret CO absorption on the copper, we used the cluster model, and calculated the molecualr orbital energy levels of by Extended Huckel Method. The energy levels of CuCO, Cu5CO, and Cu9CO Cluster were compared.
LPC-CEPSTRUM 추출을 위한 전용 프로세서의 설계
황인철,김성남,김영우,김태근,김수원 대한전자공학회 1997 電子工學會論文誌, C Vol.c34 No.8
An LPC cepstrum processor for speech recognition is implemented on CMOS array process. The designed processor contains a 24-bit floating-point MAC unit to perform the correlation quickly, which occupies the majority of operations used in the algorithm, and has 22 register files to store temporary variables. For the purpose of fast operations, the floating-point MAC consists of a 3-stage pipeline and the new post-normalization shceme is proposed and applied to it. Experimental result shows that it takes approximately 266.mu.s to process 200 samples/frame at 15 MHz clock rate. This processor runs at the maximum rate of 16.6 MHz and the number of gates are 27,760.
다이옥신의 인체 독성에 영향을 미치는 물리화학적 인자에 대한 이론적 접근
황인철,박형석 한국환경독성학회 1999 환경독성보건학회지 Vol.14 No.1
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 AMl 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.
황인철,강희철,김경곤,지선하 연세대학교의과대학 2011 Yonsei medical journal Vol.52 No.2
Purpose: The prevalence of metabolic syndrome (MetS) generally varies depending on its diagnostic definition, and many different definitions inevitably lead to substantial confusion and lack of comparability between studies. Despite extensive research, there is still no gold standard for the definition of MetS, which continues to be a matter of debate. In this study, we investigate whether and to what extent its individual components are related to the risk of cardiovascular disease (CVD) in Korean population. Materials and Methods: We used data from the 2005 Korea National Health and Nutrition Examination Survey, which is a nationally representative survey of the noninstitutionalized civilian population. The study sample consisted of 1,406 Korean adults (587 men, 819 women) who were diagnosed with MetS based on the revised National Cholesterol Education Program (NCEP) criteria. Central obesity is defined as a waist circumference cutoff point reported in Asia-Pacific criteria for obesity based on waist circumference by the World Health Organization. CVD was defined as presence of stroke, myocardial infarction, or angina pectoris on a medical history questionnaire. Results: The CVD prevalence among the subjects was 6.8% for men and 8.6% for women. Besides age, the components of MetS showing a significant difference in the number of CVD events were high fasting glucose (FG) in men and high blood pressure (BP) and high FG in women. After adjusting for gender and age, high FG was shown to yield a significant difference (odds ratio: unadjusted 2.08, adjusted 1.81), alone among all MetS components. However, after adjusting for only age, no significant difference was found. Conclusion: Fasting glucose level is the highest predicting factor for CVD in Korean patients with MetS based on the revised NECP definition.