• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.395-405
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• 1973

By use of an Integral Hellmann-Feynman formula, the cubic crystal field splitting 1O Dq in $KNiF_3$ is calculated from first principles. Numerical values of covalency parameters and necessary integrals are quoted from Sugano and Shulman. The result, 7100$cm^{-1}$, is in excellent agreement with the observed value, 7250$cm^{-1}$. It is found that higher order perturbation energy correction is of the same order of magnitude as 10 Dq itself and is, therefore, essential tin calculating 10 Dq from first principles. It is also found that the point charge potential is the dominant part of the crystal field potential.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.109-113
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• 2007

We investigated the magnetic properties of VRu(001) surface by using the all electron full-potenial linearized augmented planewave (FLAPW) energy band method within the GGA. We consider two different configurations, V and Ru surface layers, respectively. The V atoms in surface layer was calculated to have large magnetic moment of $1.71_{{\mu}_B}$ while the Ru surface layer to have nearly nonmagnetic state. The calculated spin-polarized density of states. spin density contour, and charge density were discussed in relation to the magnetic properties of VRu(001) surface.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.36-36
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• 2011

We synthesized new dye sensor based on indole compound. Through the UV-vis absorptions, we analyzed chemosensing properties to explain metal binding properties. The peak absorptions increased at 472 nm when added metal cations($Cd^{2+}$, $Cu^{2+}$, $Hg^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Ni^{2+}$ and $Cr^{3+}$) and gradually decreased the peak at 516 nm. Thus, this UV-Vis absorption behavior clearly showed the metal binding reaction. To measure energy level of used dye sensor, HOMO/LUMO energy value was calculated with cyclovaltagramm(CV) and using computational calculation method, in which we estimated the optimum structure of dye sensor. CV and computational calculation method, both compared to find suitable geometric structure. (with almost same energy values.) From the computational calculation, dye sensor has plane structure. So, Amine and ketone in the dye sensor faced each other and makes position to bind metal cations. In addition, these positions was supported pull-push electron system and generated MLCT process, when the dye sensor was bonded with the metal cations and resulted chemosensing properties. Through the electrochemical and computational calculation method analyze, we proposed the chemosensing principles that the dye sensor bind the metal cation between ketone and amine. Finally, the formation type of metal ion bindings was determined by Job's plot measurements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.556-561
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• 2022

Computational material science as an application of Density Functional Theory (DFT) to the discipline of material science has emerged and applied to the research and development of energy materials and electronic materials such as semiconductor. However, there are a few difficulties, such as generating input files for various types of materials in both the same calculating condition and appropriate parameters, which is essential in comparing results of DFT calculation in the right way. In this tutorial status report, we will introduce how to create crystal structures and to prepare input files automatically for the Vienna Ab initio Simulation Package (VASP) and Gaussian, the most popular DFT calculation programs. We anticipate this tutorial makes DFT calculation easier for the ones who are not experts on DFT programs.

• The Journal of Korean Association of Computer Education
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• v.20 no.5
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• pp.79-88
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• 2017

To upgrade the subjective question grading, we need the syntactic-semantic analysis to analyze syntatic-semantic relation between words in answering. However, since the syntactic-semantic tree has structural and semantic relation between words, we can not apply the method calculating the similarity between vectors. This paper suggests the comparing system with syntactic-semantic tree which has structural and semantic relation between words. In this thesis, we suggest similarity calculation principles for comparing the trees and verify the principles through experiments. This system will help the subjective question grading by comparing the trees and be utilized in distinguishing similar documents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.180-185
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• 2018

The literature of unfair labeling and advertising(ULA) was reviewed, along with the requirement for establishing an obligation to compensate for damage(OCD) by it based on the Act on Fair Labeling and Advertising(FLAA). ULA covers cases of possible deception or misleading consumers and thereby undermining fair trade order, or making other business entities do so. FLAA regulates OCD by ULA, but the Civil Act should also be considered for its effective results since the Act regards ULA as unlawful and duty bound to make compensation for damages arising therein. In this context, the study analyzed qualitatively 17 supreme court precedents related to OCD by ULA among a total of 119 by advertising to find the characteristics of the judgemental principles. It is found that most principles came from FLAA and the Act focusing on the meaning of false or exaggerated advertising, which is one of the following five ULA types according to its standards of judgment: its requirement for fraudulent acts, the meaning of damage by it, the perspective of calculation of damages, the requirement of OCD, and the characteristics of claim for damages. A more effective policy is suggested based on FLAA and related research should be continually carried on.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.598-603
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• 2023

Electrochemical ammonia production using catalysts offers a promising alternative to the conventional Haber-Bosch process, allowing for ambient temperature and pressure conditions, environmentally friendly operations, and high-purity ammonia production. In this study, we focus on the nitrogen reduction reactions occurring on the surfaces of ruthenium catalysts, employing first-principles calculations. By modeling reaction pathways for nitrogen reduction on the (0001) and (1000) surfaces of ruthenium, we optimized the reaction structures and predicted favorable pathways for each step. We found that the adsorption configuration of N₂ on each surface significantly influenced subsequent reaction activities. On the (0001) surface of ruthenium, the end-on configuration, where nitrogen molecules adsorb perpendicularly to the surface, exhibited the most favorable N₂ adsorption energy. Similarly, on the (1000) surface, the end-on configuration showed the most stable adsorption energy values. Subsequently, through optimized hydrogen adsorption in both distal and alternating configurations, we theoretically elucidated the complete reaction pathways required for the final desorption of NH₃.

• Journal of The Korean Association of Information Education
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• v.12 no.3
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• pp.303-312
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• 2008

In correspondence to the educational demand on study of computer principles that is recently being focused, this study promotes basic understanding on data structure and algorithm at the elementary student level through the process of simple numerical expressions and proposes effective education contents and methods. For this, an unplugged type computer education material was produced to understand the method of the computers for receiving data through activities. Also, we proposed students to create animation data to learn numerical expressions and algorithm through arrangements and linked lists. To examine educational effectiveness of this study, an experiment study was conducted through the education content and method to the subject of one class in the fifth-grade of elementary school located in OO metropolitan city. As a result, the student learned that there is a difference in calculation method between computers and people; and this enabled basic understanding on algorithm and data structure and presented positive responses to algorithm and data structure. In conclusion, it is confirmed that it is possible to provide effective education for students if the principle study of algorithm is proposed to proper levels.

• Journal of the Korean Magnetics Society
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• v.23 no.4
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• pp.117-121
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• 2013

In this study we investigated magnetism and magnetostriction of B2-structured FeX (X = Al, Si, Ni, Ga, Ge, and Sn) using a first-principles method, in order to survey the possibility of developing a transition metal based magnetostriction material. The Full-potential Linearized Augmented Plane Wave method was employed for solving the Kohn-Sham equation within the generalized gradient approximation for exchange-correlation interaction between electrons. FeX alloys are stabilized in ferromagnetic states except for the FeSi and FeGe alloys. Magnetostrcition coefficients of FeX (X = Al, Ni, Ga, and Sn) were calculated to be -5, +6, -84, -522ppm, respectively. It is noteworthy that the magnetostriction coefficient (-522ppm) of FeSn is larger than that (+400ppm) of Gafenol.

• Journal of the Korean Magnetics Society
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• v.25 no.4
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• pp.101-105
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• 2015

Recent theoretical calculations predicted that a system composed exclusively of 3d transition metals without 4d/5d transition metals or rare earth metals can have strong perpendicular magnetocrystalline anisotropy (MCA) if Fe and Ni layers are arranged appropriately. They considered only Fe-terminated surfaces, noting that Fe/MgO(001) and CoFeB/MgO(001) show strong perpendicular MCA. In this paper, we investigate magnetism and MCA of Ni/Fe(001) surface where Ni layer is positioned at the surface, by using complementarily the first principles calculational methods of Vienna Ab-initio Simulation Package (VASP) and Full-potential Linearized Augmented Plane Wave (FLAPW) method. Comparing results of magnetism and MCA obtained by VASP with the results by FLAPW method, we find the VASP results do not show big difference from results by FLAPW method. Magnetic moments of Fe and Ni are enhanced due to strong hybridization between Fe and Ni bands. MCA of Ni/Fe(001) is parallel to the surface, which implies the surface termination plays a crucial role in determining MCA of a system.