• Journal of Magnetics
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• v.20 no.1
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• pp.11-20
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• 2015

In this work, Monte Carlo simulation was employed to model the stretchable Ising monolayer film to investigate the effect of the spatial distance variation among magnetic atoms on magnetic behavior of the film. The exchange interaction was considered as functions of initial interatomic distance and the stretched distance (or the strain). Following Bethe-Slater picture, the magnetic exchange interaction took the Lennard-Jones potential-like function. Monte Carlo simulations via the Wolff and Metropolis algorithms were used to update the spin systems, where equilibrium and dynamic magnetic profiles were collected. From the results, the strain was found to have strong influences on magnetic behavior, especially the critical behavior. Specifically, the phase transition point was found to either increase or decrease depending on how the exchange interaction shifts (i.e. towards or away from the maximum value). In addition, empirical functions which predict how the critical temperatures scale with initial interatomic distance and the strain were proposed, which provides qualitatively view how to fine tune the magnetic critical point in monolayer film using the substrate modification induced strain.

• Journal of Fashion Business
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• v.26 no.5
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• pp.49-61
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• 2022

Advancements in technology and the proliferation of digital services have highlighted the importance of luxury brands in service environments. Based on the social exchange theory, this study investigated the interaction between customers and luxury brands in a traditional offline service encounter and a digital online service encounter. The interaction area was classified into three parts: human-human, human-digital, and human-physical environments. We qualitatively investigated the practitioners' working experiences with luxury brands. The study determined that both online and offline service encounter interactions between luxury brands and customers have become diverse. First, forming a special relationship with customers and frontline employees in traditional service encounters is important. Second, luxury brands should focus on the interaction among customers. Third, various digital tools should be considered to provide information about the brand to customers. Fourth, the exclusive benefits of offline service encounters should be maximized to stimulate positive experiences. The findings provide valuable insight to scholars and marketers on the new interaction phase between customers and luxury brands in the digital age.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11B
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• pp.1005-1016
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• 2006

As the increment usage of Internet, the security systems's importance is emphasized. The current Internet Key Exchange protocol(IKE) which has been used for key exchange of security system, was pointed out a problem of efficiency and stability. In this research, we try to resolve those problems, and evaluate the newly designed Key Exchange protocol in the IPsec interaction test bed system environment. In this research we implemented the new Key Exchange Protocol as a recommendation of RFC proposal, so as to resolve the problem which was pointed out the key exchange complexity and the speed of authentication process. We also designed the defense mechanism against the Denial of Service attack. We improved the key exchange speed as a result of simplification of complex key exchange phase, and increased efficiency as a result of reuse the preexistence state value when it's renegotiated.

• Journal of Magnetics
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• v.6 no.4
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• pp.119-121
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• 2001

Monte Carlo simulation was employed to study the phase transition in the classical Heisenberg ferromagnet with variable interlayer interactions. The measured transition temperatures show a strong logarithmic dependence on J/J'where J and J'are the intralayer and the interlayer exchange interaction, respectively. The results were compared with the theoretical expectations and an empirical formula for the critical coupling was stained.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.277-278
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• 2000

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1704-1710
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• 2010

The structure of a 2D grid-like copper(II) complex [Cu$(NCO)_2$(pyz)](pyz=pyrazine) (1) consists of 1D chains of Cu-pyz units connected by double end-on (EO) cyanato bridges. Each Cu(II) ion has a distorted octahedral coordination, completed by the four EO cyanato and two pyrazine ligands. Magnetic interactions through EO cyanato and pyrazine bridges in 1 are discussed on the basis of DFT broken-symmetry calculations at the B3LYP level. For model dicopper(II) complexes I (bridged by cyanato) and II (bridged by pyrazine), electronic structure calculations reproduce very well the experimental couplings for the S = 1/2 ferromagnetic and antiferromagnetic exchange-coupled 2D system: the calculated exchange parameters J are +1.25 $cm^{-1}$ and -3.07 $cm^{-1}$ for I and II, respectively. The $\sigma$ orbital interactions between the Cu $x^2-y^2$ magnetic orbitals and the nitrogen lone-pair orbitals of pyrazine are analyzed from the viewpoint of through-bond interaction. The energy splitting of 0.106 eV between two SOMOs indicates that the superexchange interaction should be antiferromagnetic in II. On the other hand, there are no bridging orbitals that efficiently connect the two copper(II) magnetic orbitals in I because the HOMOs of the basal-apical NCO bridge do not play a role in the formation of overlap interaction pathway. The energy separation in the pair of SOMOs of I is calculated to be very small (0.054 eV). This result is consistent with the occurrence of weakly ferromagnetic properties in I.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.467-471
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• 2011

Spin exchange interactions of $(C_2N_2H_{10})[Fe(HPO_3)F_3]$ were examined by performing a spin dimer analysis based on extended Huckel tight binding method and a mapping analysis based on first principles density functional theory. Spin exchange interactions occur through the super-superexchange paths $J_1$ and $J_2$ in $(C_2N_2H_{10})[Fe(HPO_3)F_3]$. In the super-superexchange path $J_2$ magnetic orbital interactions between eg-block levels are much stronger than those from $t_{2g}$-block levels. Both electronic structure calculations show that the spin exchange interaction through the super-superexchange path $J_2$ is much stronger than that of $J_1$.

• Advances in environmental research
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• v.2 no.3
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• pp.167-177
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• 2013

We investigated that removal of aqueous U(VI) by nano-sized Zero Valent Iron (nZVI) and Fe(II) bearing minerals (controls) in this study. Iron particles showed different U(VI) removal efficiencies (Mackinawite: 99%, green rust: 95%, nZVI: 91%, magnetite: 87%, pyrite: 59%) due to their different PZC (Point of Zero Charge) values and surface areas. In addition, noticeable amount of surface Fe(II) (181 ${\mu}M$) was released from nZVI suspension in 6 h and it increased to 384 ${\mu}M$ in the presence of U(VI) due to ion-exchange of U(VI) with Fe(II) on nZVI surface. Analysis of Laser-Induced Breakdown Detection (LIBD) showed that breakdown probabilities in both filtrates by 20 and 200 nm sizes was almost 24% in nZVI suspension with U(VI), while 1% of the probabilities were observed in nZVI suspension without U(VI). It indicated that Fe(II) colloids in the range under 20 nm were generated during the interaction of U(VI) and nZVI. Our results suggest that Fe(II) colloids generated via ion-exchange process should be carefully concerned during long-term remediation site contaminated by U(VI) because U could be transported to remote area through the adsorption on Fe(II) colloids.

• Journal of the Korean Magnetics Society
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• v.24 no.4
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• pp.97-100
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• 2014

We have studied electronic and magnetic structure of Mn-dimer molecule using OpenMX method based on density functional method. The calculated density of states shows that the four O atoms split $e_g$ and $t_{2g}$ energy levels. The energy splitting by the crystal field is smaller than bulk MnO with cubic structure, because of small coordination number of atoms. Total energy with antiferromagnetic spin configuration is lower than that of ferromagnetic configurations. Calculated exchange interaction J between Mn atoms is one order larger than that of the other Mn-O magnetic molecules. That comes from the direct exchange interaction between Mn 3d orbitals and the super-exchange interactions caused by strong ${\sigma}$-bonding of Mn-O orbitals.

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.140-144
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• 2017

We have studied electronic and magnetic structure of cubane-type Co magnetic molecule using density functional method. The calculated density of states show $Co^{+2}$ ionic state and high-spin state because of large exchange interaction between inside Co 3d electrons. The exchange interaction J between Co atoms depends Co-O-Co angle. The calculated J is ferromagnetic with right angles. On the other hand J is antiferromagnetic with large angles since super-exchange interactions between $Co^{+2}$ atoms. It induces that Co cubane has a antiferromagnetic spin structure of AFM1 = [${\uparrow}{\uparrow}{\downarrow}{\downarrow}$]