• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.393-400
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• 2021

As the recent climate problems are getting worse year after year, the demands for clean energy materials have highly increased in modern society. However, the candidate material classes for clean energy expand rapidly and the outcomes are too complex to be interpreted at laboratory scale (e.g., multicomponent materials). In order to overcome these issues, the first-principles calculations are becoming attractive in the field of material science. The calculations can be performed rapidly using virtual environments without physical limitations in a vast candidate pool, and theory can address the origin of activity through the calculations of electronic structure of materials, even if the structure of material is too complex. Therefore, in terms of the latest trends, we report academic progress related to the first-principles calculations for design of efficient electrocatalysts. The basic background for theory and specific research examples are reported together with the perspective on the design of novel materials using first-principles calculations.

• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.83-87
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• 2002

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.273-281
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• 2016

This review examines computational simulations of thermoelectric properties, such as electrical conductivity, Seebeck coefficient, and thermal conductivity. With increasing computing power and the development of several efficient simulation codes for electronic structure and transport properties calculations, we can evaluate all the thermoelectric properties within the first-principles calculations with the relaxation time approximation. This review presents the basic principles of electrical and thermal transport equations and how they evaluate properties from the first-principles calculations. As a model case, this review presents results on $Bi_2Te_3$ and Si. Even though there is still an unsolved parameter such as the relaxation time, the effectiveness of the computational simulations on the transport properties will provide much help to experimental scientist researching novel thermoelectric materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.733-738
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• 2009

Mechanical properties of <001> silicon nanowires are presented. In particular, predictions from the calculations based on different length scales, first principles calculations, atomistic calculations, and continuum nanomechanical theory, are compared for <001> silicon nanowires. There are several elements that determine the mechanics of silicon nanowires, and the complicated balance between these elements is studied. Specifically, the role of the increasing surface effects and reduced dimensionality predicted from theories of different length scales are compared. As a prototype, a Tersoff-based empirical potential has been used to study the mechanical properties of silicon nanowires including the Young's modulus. The results significantly deviates from the first principles predictions as the size of wire is decreased.

• Journal of Magnetics
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• v.18 no.2
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• pp.81-85
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• 2013

We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy ($V_N$) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of $V_N$ defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and $V_N$ states, the spin-polarization on the Cu atoms in the InN lattice is reduced by $V_N$ defect. So, it shows a weak ferromagnetic behavior.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.611-617
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• 2021

The mechanical properties of α-Na₃(U_0.84(2),Na_0.16(2))O₄ have been researched using the first-principles calculations combined with the quasi-harmonic Debye model. The obtained lattice parameters agree well with the published experimental data. The results of elastic constants indicate that α-Na₃(U_0.84(2),Na_0.16(2))O₄ is mechanically stable. The polycrystalline moduli are predicted. The results show that the α-Na₃(U_0.84(2),Na_0.16(2))O₄ exhibits brittleness and possesses obvious elastic anisotropy. The hardness shows that it can be considered a "soft material". Furthermore, the Debye temperature θ_D and the minimum thermal conductivity k_min are also discussed, respectively. Finally, the thermal expansion coefficient α, isobaric heat capacity C_P and isochoric heat capacity C_V are evaluated through the quasi-harmonic Debye model.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.12a
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• pp.74-75
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• 2009

First-principles calculations were carried out to investigate the crystal stability and magnetism of $Fe_{16}C_2$ and $Fe_{16}C_2$. Our precise calculations show that the structure of high carbon phase is $Fe_{16}C_2$ and this structure is more stable in the ferromagnetic state than the nonmagnetic state. The Fe atoms induced negative magnetic moment at the C atoms, which interact with the nearest Fe atoms.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.65-66
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.226-226
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• 2017

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.282-284
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• 2013