• Applied Science and Convergence Technology
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• v.25 no.1
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• pp.19-24
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• 2016

In this study, we evaluated the change of electronic structure during redox process in cerium-doped $ZrO_2$ grown by sol gel method. By sol-gel method, we could obtain cerium-doped $ZrO_2$ in high oxygen partial pressure and low temperature. After post annealing process in nitrogen ambient, the film is deoxidized. We used spectroscopic and theoretical methods to analysis change of electronic structure. X-ray absorption spectroscopy (XAS) for O K1-edge and Density Functional Theory (DFT) calculation using VASP code were performed to verify the electronic structure of the film. Also, high resolution x-ray photoelectron spectroscopy (HRXPS) for Ce 3d was carried out to confirm chemical bond of cerium doped $ZrO_2$. Through the investigation of the electronic structure, we verified as followings. (1) During reduction process, binding energy of oxygen is increase. Simultaneously, oxidation state of cerium was change to 4+ to 3+. (2) Cerium 4+ and cerium 3+ states were generated at different energy level. (3) Absorption states in O K edge were mainly originated by Ce 4+ $f_0$ and Ce 3+, while occupied states in valance band were mainly originated from Ce 4+ $f_2$.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.576-582
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• 1998

The purpose of the study was to determine the ability of the caries activity test, 'Cariostat' to identify preschool children with dental caries. The subjects of this study were 76 children of 3 to 5 years of age. Oral examination was carried out to assess the caries experience using a mirror and explorer. In all subjects buccal plaque samples were obtained, incubated, and scored as the manufacturer's instructions for the Cariostat test. Statistical analyses were used with the Crosstabulation. The test group exhibited mean dft index 5.21, while 27.63% of subjects were caries free and had no restorations. The sensitivity of the Cariostat test was found to be 98.8% while the specificity was found to be 19.05% The results showed that caries activity measured by visual reading was highly significant to the Cariostat score and dft index(P<0.001). The Cariostat method has indicated the future possible occurrence of caries. The use of this method is meant to require in the caries prevention program.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.133-133
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• 2015

Recently, it has been shown that the ${\omega}B97X-D/aVTZ$ method is strongly recommended as the best practical density functional theory(DFT) for rigorous and extensive studies of saturated or unsaturated $C_4F_8$ species because of its high performance and reliability especially for van der Waals interactions. All the feasible isomerization and dissociation paths of $C_4F_8$ molecules were investigated at this theoretical level and rate constants of their chemical reactions were computed by using variational transition-state theory for a deep insight into $C_4F_8$ reaction mechanisms. Fates and roles of C4F8 molecules and their fragments in plasma phases could be clearly explained based on our computational results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1113-1116
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• 2003

In this paper, it is suggested that the technology sound measurement which is to search the inferiority of the plate during the pressing. We evaluate whether there is a inferiority by analysing and comparing the satisfactory and inferior plate with the method of a spectrum analysis by measuring the sound which is emitted during pressing. We designed the analysis algorithm to detect inferior plate throughout comparison of measured sound data using FFT, DFT and DASYLab S/W. In addition to these, we suggest the way to compare both inferior and satisfactory signal statistically.

• Journal of the Korean Chemical Society
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• v.59 no.6
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• pp.483-487
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• 2015

The different calculated quantum chemical descriptors by DFT method were used for prediction of some sulphanilamide Schiff bases inhibitor activity as a binding constant (log K). Multiple linear regression (MLR) and artificial neural network (ANN) were employed for developing the useful quantitative structure activity relationship (QSAR) model. The obtained results presented superiority of ANN model over the MLR one. The offering QSAR model is very easy to computation and Physico-Chemically interpretable. Sensitivity analysis was used to determine the relative importance of each descriptor in ANN model. The order of importance of each descriptor according to this analysis is: molecular volume, molecular weight and dipole moment, respectively. These descriptors appear good information related to different structure of sulphanilamide Schiff bases can participate in their inhibitor activity.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.944-945
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• 2008

전동기를 제어하기 위한 속도를 검출하는 장치로 광학적 엔코더를 일반적으로 많이 사용하고 있으며 레졸바는 구조적으로 엔코더를 전동기에 장착하기가 어려운 경우에 사용하고 있다. 때문에 레졸바는 엔코더와 비교하여 가격면에서 불리하지만 회전자의 절대위치를 검출하기 때문에 자극의 위치를 기준으로 제어하는 경우에 유용하다. 본 연구는 레졸바에 의하여 전동기의 회전속도를 검출하는 방법으로 최소한의 하드웨어인 필터를 사용하고 프로그램에 의한 디지털방법의 속도검출기에 관한 것이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.189.2-189.2
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• 2014

The most stable adsorption structures and energies of four tautomerized forms (keto-1, enol-1, keto-2, and enol-2) of 3-methyl 5-pyrazolone (MP) adsorbed on Ge(100) surfaces have been investigated by Density Functional Theory (DFT) calculation method. Among its four tautomerized forms, we confirmed three tautomerized forms except keto-1 form show the stable adsorption structures when they adsorbed on the Ge(100)-$2{\times}1$ surface as we calculate the respective stable adsorption structures, activation barrier, transition state energy, and reaction pathways. Moreover, among three possible adsorption structures, we acquired that enol-2 form has most stable adsorption structure with O-H dissociated N-H dissociation bonding structure.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1229-1234
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• 2005

The conformational, configurtational behavior and the structure of N-2-(1,4-Dioxane)-N'-(4-methylbenzenesulfonyl)-O-(4-methylphenoxy) isourea 1 has been studied using DFT method. Calculations predict the imidoyl amino group of the dioxane ring prefers axial conformation and that the tosyl and tolyl groups about the C=N bond retain E configuration. The anomeric effect controls the population of dioxane ring conformers, and anomers. Intramolecular hydrogen bonds contribute to the stability of E isomers. The computational analysis of 1 complements the X-ray findings.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2491-2494
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• 2013

The effect of additives in an electrolyte solution on the conversion efficiency of a dye sensitized solar cell was investigated. A density functional theory (DFT) method was used to examine the physical and chemical properties of nitrogen-containing additives adsorbed on a $TiO_2$ surface. Our results show that additives which cause lower partial charges, higher Fermi level shifts, and greater adsorption energies tend to improve the performance of DSSCs. Steric effects that prevent energy losses due to electron recombination were also found to have a positive effect on the conversion efficiency. In this work, 3-amino-5-methylthio-1H-1,2,4-triazole (AMT) has been suggested as a better additive than the most popular additive, TBP, and verified with experiments.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.273-277
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• 2013

We apply a density functional theory (DFT) and DFT-based non-equilibrium Green's function approach to study the electronic and transport properties of graphene nanoribbons (GNRs) co-doped with boron-nitrogen, nitrogen-phosphorus and boron-phosphorus. We analyze the structures and charge transport properties of co-doped GNRs and particularly focus on the novel effects that are absent for the single N-, B-, or P-doped GNRs. It is found that co-doped GNRs tend to be doped at the edges and the electronic structures of co-doped GNRs are very sensitive to the doping sites. Also, in case of B-N and B-P co-doped GNRs, conductance dips of single-doped GNRs disappeared with the disappearance of localized states associated with doped atoms. This may lead to a possible method of band engineering of GNRs and benefit the design of graphene electronic devices.