• 반도체디스플레이기술학회지
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• 제9권3호
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• pp.1-4
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• 2010

First-principles calculations based on spin density functional theory are performed to study the spin-resolved electronic properties of AlN doped with a Cu concentration of 6.25%-18.75%. The ferromagnetic state is more energetically favorable state than the antiferromagnetic state or the nonmagnetic state. For $Al_{0.9375}Cu_{0.0625}N$, a global magnetic moment of 1.26 mB per supercell, with a localized magnetic moment of 0.75 $m_B$ per Cu atom is found. The magnetic moment is reduced due to an increase in the number of Cu atoms occupying adjacent cation lattice position. For $Al_{0.8125}Cu_{0.1875}N$, the magnetism of the supercell disappears by the interaction of the neighboring Cu atoms. The nonmagnetic to ferromagnetic phase transition is found to occur at this Cu concentration. The range of concentrations that are spin-polarized should be restricted within very narrow.

• 조명전기설비학회논문지
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• 제29권3호
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• pp.8-21
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• 2015

Technology for electric lighting has been evolving from Incandescent Lamp(IL) through Fluorescent Lamp(FL) and currently to Solid State Lighting(SSL) such as LED for more than 130 years of time. However, it took more than 100 years until the transition from IL to FL across overall society. That is because the transition is the Socio-Technical Transition(STT) which involves various social elements. This study investigated and analyzed the theories regarding STT, and applied the Multi-Level Perspective(MLP) theory to the case of electric lighting. A qualitative contents analysis was used with secondary data as research method, and the analyzed result was visualized based on the frame of MLP theory. The STT of electric lighting from IL to FL took place as the order of Technical Niche, Socio-Technical Regime and Landscape. Specifically, in Technical Niche level: Establishing Market Niche, Price-Performance Improvement, Learning Process and Support of Powerful Group took place. In Socio-Technical Regime level: Changes in Social Network, Changes in Technology and Changes in Rules. In Landscape level: Macro-Political Development, Socio-Economic Trends and Macro-Economic Trends took place in consecutive order.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1187-1194
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• 2011

The hydrogen abstraction reaction of $CF_3CH_2CHO$ + OH has been studied theoretically by dual-level direct dynamics method. Two stable conformers, trans- and cis-$CF_3CH_2CHO$, have been located, and there are four distinct OH hydrogen-abstraction channels from t-$CF_3CH_2CHO$ and two channels from c-$CF_3CH_2CHO$. The required potential energy surface information for the kinetic calculation was obtained at the MCG3-MPWB//M06-2X/aug-cc-pVDZ level. The rate constants, which were calculated using improved canonical transitionstate theory with small-curvature tunneling correction (ICVT/SCT) were fitted by a four-parameter Arrhenius equation. It is shown that the reaction proceeds predominantly via the H-abstraction from the -CHO group over the temperature range 200-2000 K. The calculated rate constants were in good agreement with the experimental data between 263 and 358 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.486-489
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• 2002

Temperature(T) dependence of the sheet resistance( $R_{$\square$}$) has been investigated on the c-axis oriented thin films of the (Bi2212/Bi2201) mixed crystal with different molar fractions. The $R_{$\square$}$-T superconducting characteristic deteriorated with reduction of the Bi2212 fraction, and almost disappears at 48 mol% where a superconductor-to-insulator transition took place, with the resistance on the normal state, RN, reaching 4.l㏀ at 80 K. This $R_{N}$ value is close to the universal quantum number, h/(2e)$^2$≡6.5㏀ predicted by the Kosterlitz-Thouless(KT) transition theory. The $R_{$\square$}$-T characteristics of the 48 mol% thin film can be elucidated as a competitive process of KT transition brought about by charge or vortex in the two-dimensional layer structure.e.

• Transactions on Electrical and Electronic Materials
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• 제3권2호
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• pp.20-23
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• 2002

Temperature (T) dependence of the sheet resistance (R$\_$$\square$/) has been investigated an the c-axis oriented thin films of the (Bi2212/Bi2201) mixed crystal with different molar fractions. The R$\_$$\square$/-T superconducting characteristic deteriorated with reduction of the Bi2212 fraction, and almost disappears at 48 mol% where a superconductor-to-insulator transition too k place, with the resistance on the normal state, R$\_$N/, reaching 4.1 kΩka at 80 K. This R$\_$$\square$/ value is close to the universal quantum number, h/(2e)$_2$≡ 6.5 kΩ predicted by the Kosterlitz-Thouless (KT) transition theory. The R$\_$$\square$/-T characteristics of the 48 mol% thin film can be elucidated as a competitive process of KT transition brought about by charge or vortex in the two-dimensional layer structure.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.365-371
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• 2010

The multiconfiguration molecular mechanics (MCMM) algorithm was used to generate potential and vibrationally adiabatic energy surfaces for excited-state tautomerization in the 1:1 7-azaindole:$H_2O$ complex. Electronic structures and energies for reactant, product, transition state were computed at the CIS/6-31G(d,p) level of theory. The potential and vibrationally adiabatic energies along the reaction coordinate were generated step by step by using 16 high-level Shepard points, which were computed at the CIS/6-31G(d,p) level. This study shows that the MCMM method was applied successfully to make quite reasonable potential and adiabatic energy curves for the excited-state double proton transfer reaction. No stable intermediates are present in the potential energy curve along the reaction coordinate of the excited-state double proton transfer in the 1:1 7-azaindole:$H_2O$ complex, indicating that these two protons are transferred concertedly. The change in the bond distances along the reaction coordinate shows that two protons move very asynchronously to make an $H_3O^+$-like moiety at the transition state.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2343-2353
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• 2007

We report the application of time-dependent density functional theory (TDDFT) to the calculation of potential energy profile relevant to the excited state intramolecular proton transfer (ESIPT) processes in title molecules. The TDDFT single point energy calculations along the reaction path have been performed using the CIS optimized structure in the excited state. In addition to the Stokes shifts, the transition energies including absorption, fluorescence, and 0-0 transition are estimated from the TDDFT potential energy profiles along the proton transfer coordinate. The excited state TDDFT potential energy profile of SA and 3ASA resulted in very flat function of the OH distance in the range ROH = 1.0-1.6 A, in contrast to the relatively deep single minimum function in the ground state. Furthermore, we obtained very shallow double minima in the excited state potential energy profile of SA and 3ASA in contrast to the single minimum observed in the previous work. The change of potential energy profile along the reaction path induced by the substitution of electron donating groups (-NH2 and -OCH3) at different sites has been investigated. Substitution at para position with respect to the phenolic OH group showed strong suppression of excited state proton dislocation compared with unsubstitued SA, while substitution at ortho position hardly affected the shape of the ESIPT curve. The TDDFT results are discussed in comparison with those of CASPT2 method.

• Bulletin of the Korean Chemical Society
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• 제24권6호
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• pp.763-770
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• 2003

The $BH_5$ molecule, which is suggested as an intermediate of the acidolysis of $BH_4^-$, contains a weak two-electron-three-center bond and it requires extremely high-level of theories to calculate the energy and structure correctly. The structures and energies of $BH_5$ and the transition state for the hydrogen scrambling have been studied using recently developed multi-coefficient correlated quantum mechanical methods (MCCMs). The dissociation energies and the barrier heights agree very well with the previous results at the CCSD(T)/ TZ(3d1f1g, 2p1d) level. We have also calculated the potential energy curves for the dissociation of $BH_5$ to $BH_3$ and $H_2$. The lower levels of theory were unable to plot correct potential curves, whereas the MCCM methods give very good potential energy curves and requires much less computing resources than the CCSD(T)/ TZ(3d1f1g,2p1d) level. The potential energy of the $BH_5$ scrambling has been obtained by the multiconfiguration molecular mechanics algorithm (MCMM), and the rates are calculated using the variational transition state theory including multidimensional tunneling approximation. The rate constant at 300 K is 2.1 × $10^9s^{-1}$, and tunneling is very important.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.212-217
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• 1992

In this paper, a two ports machine(TPM) model for discrete event dynamic systems(DEDS) is proposed. The proposed model is a finite state machine which has two inputs and two outputs. Inputs and outputs have two components, events and informations. TPM is different from other state machine models, since TPM has symmetric input and output. This symmetry enables the block diagram representation of the DEDS with TPM blocks, summing points, multiplying points, branch points, and connections. The graphical representation of DEDS is analogous to that of control system theory. TPM has a matrix representation of its transition and information map. This matrix representation simplifies the analysis of the DEDS.

• Bulletin of the Korean Chemical Society
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• 제4권2호
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• pp.84-87
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• 1983

Transition state structures were calculated for A and M routes of ${\omega}$-alkenyl radical cyclization (n = 2∼4) using MINDO/3-RHF method. Results of our analysis of HOMO level changes indicated that the transition state stability is not controlled by the decoupling effect alone as Bischof suggested, but in greater degree it is determined by through-bond interaction of the HOMOs with the framework $HO-{\sigma}$ or $LU-{\sigma}^*$ orbitals. In case of larger n (n > 4), the product stability was considered to be the main cause of M route dominance in the cyclization.