• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1277-1280
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• 2005

• EDISON SW 활용 경진대회 논문집
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• 제2회(2013년)
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• pp.25-35
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• 2013

The intramolecular magnetic coupling constant (J) values of diradical-based magnet models (S1-S5) were studied using unrestricted density functional theory. The model systems were designed with series of oxoverdazyl radicals (o-Ver(N) and o-Ver(C)) linked through a benzene coupler. They were divided according to either connectivity of the radical (C or N) or geometrical topology (meta- and para-) of benzene coupler. Reasonable relationship was found between spin density distribution and sign of J value. With our results we determined ferromagnetic (positive J value) and antiferromagnetic (negative J value) interactions. J values were also calculated along the twisting movement by the scan of dihedral angles between the radical and the coupler. An overall trend was found as absolute value of J decreased over increasing torsion angles.

• 한국전산유체공학회지
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• 제18권2호
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• pp.78-84
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• 2013

In this paper, numerical simulations of both low- and high-frequency buzz phenomena at the throttle ratios (T.R.) in Nagashima's experiment are performed. The dominant frequencies of the low-and high-frequency buzz in the experiment are about 109 Hz with T.R.=0.97 and 376 Hz with T.R.=0.55, respectively. An axisymmetric solver with the S-A turbulence model is used for the simulations, and DFT(Discrete Fourier Transform) on pressure histories is conducted for the buzz frequency analysis. In the present simulations, the free-stream Mach number and the Reynolds number based on the inlet diameter are 2 and $10^7$, respectively. Both the low- and high-frequency buzz phenomena are accomplished without the changes in the grid topology. The dominant frequency of the simulation is about 125 Hz with T.R.=0.97, while it is 399 Hz with T.R.=0.55.