• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.4
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• pp.617-628
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• 2022

Ascon is one of the final round candidates of the NIST lightweight cryptography contest, which has been underway since 2015, and supports hash modes Ascon-Hash and Ascon-Xof. In this paper, we develop a MILP model for collision attack on the Ascon-Hash and search for a differential trail that can be used in a quantum setting through the model. In addition, we present an algorithm that allows an attacker who can use a quantum computer to find a quantum free-start collision attack of 3-round Ascon-Hash using the discovered differential trail. This attack is meaningful in that it is the first to analyze a collision attack on Ascon-Hash in a quantum setting.

• Journal of the Korean Chemical Society
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• v.20 no.2
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• pp.97-110
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• 1976

Effects of direct multiple quantum excitations in vibrational energy transfer were investigated. Vibrational transition probabilities for 0${\rightarrow}$2, 0${\rightarrow}$3, and 0${\rightarrow}$4 excitations were explicitly formulated including both direct 0→n excitations and stepwise single quantum processes. For the formulation the perturbing force was derived from the exponential potential including terms up to fourth order in the vibrational amplitude. The head-on collinear collision model between a harmonic oscillator and an incident particle was employed, and the formulation was based on the semiclassical approximation. Numerical results were obtained for five different collision systems (Ar${\cdots}$O-N, He${\cdots}$H-H, He${\cdots}$H-Cl, 5${\cdots}$1-2, 2${\cdots}$12-12). Comparison between the present results and those obtained using the linearized interaction potential showed that the overall effect of including the direct multiple quantum transition is to decrease the probabilities at low collision energies and to increase them at high energies. The present results were found to be significantly different from those obtained using the linearized potential for collision systems He${\cdots}$H-H, He${\cdots}$H-Cl, and 5${\cdots}$1-2. For systems Ar${\cdots}$O-N and 2${\cdots}$12-12 the differences were negligible.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.721-726
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• 2001

The vibrational transition probability expressions for the forced Morse oscillator have been derived using the commutation relations of the anharmonic Boson operators. The formulation is based on the collinear collision model with the exponential repulsive potential in the framework of semiclassical collision dynamics. The sample calculation results for H2+ He collision system, where the anharmonicity is large, are in excellent agreement with those from an exact, numerical quantum mechanical study by Clark and Dickinson, using the reactance matrix. Our results, however, are markedly different from those of Ree, Kim and Shin's in which they approximate the commutation operator I。 as unity, the harmonic oscillator limit. We have concluded that the quantum number dependence in I。 must be retained to get accurate vibrational transition probabilities for the Morse oscillator.

• Bulletin of the Korean Chemical Society
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• v.8 no.2
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• pp.88-96
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• 1987

The effects of initial vibrational energy on VV energy transfer in the collinear collision of two diatomic molecules, either homonuclear or heteronuclear, has been studied over a range of collision energies in classical mechanics. When initial vibrational energy is very large, only a small fraction of vibrational energy in the excited molecule is transferred to the colliding partner. In this case, the VV step is found to be strongly coupled with VT during the collision. At low collision energies, energy transfer in the homonuclear case of $O_2$+ $O_2$ with small initial vibrational energy is found to be very inefficient. In the heteronuclear case of CH + HC with the initial energy equivalent to one vibrational quantum, VV energy exchange is found to be very efficient at such energies. Between 0.3 and 0.5 ev, nearly all of vibrational energy of the excited molecule with one to about three vibrational quanta in CH + HC is efficiently transferred to the colliding partner through pure VV process in a sequence of down steps during the collision. The occurrence of multiple impacts during the collision of two heteronuclear molecules and the collisional bond dissociation of homonuclear molecules are also discussed.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.436-438
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• 1995

Based on the collisional time-correlation function approach a general analytical expression has been derived for the double differential cross-section with respect to the scattering angle and the final rotational energy, which can be applied to molecules with non-zero electronic orbital angular momentum after collision with fast hydrogen atoms. By integrating this expression another very simple expression, which gives the final rotational distribution as a function of the rotational quantum number, has also been derived. When this expression is applied to NO(2Π1/2, v'=1) and NO(2Π3/2, v'=1, 2, 3), it can reproduce the experimental rotational distribution after collision with fast H atom very well. The average rotational quantum number and average rotational energy using this expression are also in good agreement with those deduced from the experimental distributions.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.151-157
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• 2014

We have reported the reaction probability, integral reaction cross section, and rate constant for the title system calculated with the aid of a time-dependent wave packet approach. The ab initio potential energy surface (PES) of Prudente et al. (Chem. Phys. Lett. 2009, 474, 18) is employed for the purpose. The calculations are carried out over the collision energy range of 0.05-1.4 eV for the two reaction channels of H + LiH ${\rightarrow}$ Li + $H_2$ and $H_b$ + $LiH_a$ ${\rightarrow}$ $LiH_b$ + $H_a$. The Coriolis coupling (CC) effect are taken into account. The importance of including the Coriolis coupling quantum scattering calculations are revealed by the comparison between the Coriolis coupling and the centrifugal sudden (CS) approximation calculations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.27-38
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• 2002

A new self-consistent mathematical model for semiconductor quantum well device was developed. The model was based on the direct solution of the Boltzmann transport equation, coupled to the Schrodinger and Poisson equations. The solution yielded the distribution function for a two-dimensional electron gas(2DEG) in quantum well devices. To solve the Boltzmann equation, it was transformed into a tractable form using a Legendre polynomial expansion. The Legendre expansion facilitated analytical evaluation of the collision integral, and allowed for a reduction of the dimensionality of the problem. The transformed Boltzmann equation was then discretized and solved using sparce matrix algebra. The overall system was solved by iteration between Poisson, Schrodinger and Boltzmann equations until convergence was attained.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.14-26
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• 2002

A new model for degenerate semiconductor quantum well devices was developed. In this model, the multi-subband Boltzmann transport equation was formulated by applying the Pauli exclusion principle and coupled to the Schrodinger and Poisson equations. For the solution of the resulted nonlinear system, the finite difference method and the Newton-Raphson method was used and carrier energy distribution function was obtained for each subband. The model was applied to a Si MOSFET inversion layer. The results of the simulation showed the changes of the distribution function from Boltzmann like to Fermi-Dirac like depending on the electron density in the quantum well, which presents the appropriateness of this modeling, the effectiveness of the solution method, and the importance of the Pauli -exclusion principle according to the reduced size of semiconductor devices.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.74-75
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• 2000

The past few decades have witnessed the development of very robust technique, known as magneto-optical trap(MOT), for cooling and trapping of neutral atoms using lasers and magnetic fields. This technique can easily produce cooled atoms to a temperature range of nano-kelvin $s^{(1)}$ . These laser cooled and trapped atoms have found applications in various fields, such as ultrahigh resolution spectroscopy, precision atomic clocks, very cold atomic collision physics, Bose-Einstein Condensation, the Atom laser, etc. Particularly, a few isolated atoms of very low temperature are needed in the cavity QED studies in the optical regime. One can obtain such atoms from a MOT using the atomic fountain technique. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT. And then launch them in the vertical (1, 1, 1) direction with respect to cooling beams, using moving molasses technique. Recently, this technique combined with the cavity-QED has opened an active area of basic research. This way atoms can be strongly coupled to the optical radiation in the cavity and leads to various new effects. Trapping of single atom after separating it from MOT in the high Q-optical cavity is actively initiated presentl $y^{(2.3)}$. This will help to sharpen our understanding of atom-photon interaction at quantum level and may lead to the development of single-atom laser. Our efforts to develop an $^{85}$ Rb-atomic fountain is in progress. (omitted)

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2841-2848
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• 2010

Quasiclassical trajectory (QCT) method has been used to investigate stereodynamics information of the reaction $O(^1D)+H_2{\rightarrow}\;OH$+H on the DK (Dobbyn and Knowles) potential energy surface (PES) at a collision energy of 23.06 kcal/mol, with the initial quantum state of reactant $H_2$ being set for v = 0 (vibration quantum number) and j = 0-5 (rotation quantum number). The PDDCSs (polarization dependent differential cross sections) and the distributions of P($\theta_r$), P($\phi_r$), P($\theta_r$, $\phi_r$) have been presented in this work. The results demonstrate that the products are both forward and backward scattered. As j increases, the backward scattering becomes weaker while the forward scattering becomes slightly stronger. The distribution of P($\theta_r$) indicates that the product rotational angular momentum j' tends to align along the direction perpendicular to the reagent relative velocity vector k, but this kind of product alignment is found to be rather insensitive to j. Furthermore, the distribution of P($\phi_r$) indicates that the rotational angular momentum vector of the OH product is preferentially oriented along the positive direction of y-axis, and such product orientation becomes stronger with increasing j.