• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.149-156
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• 2006

The circular list coloring is a circular version of list colorings of graphs. Let $\chi_{c,l}$ denote the circular choosability(or the circular list chromatic number). In this paper, the circular choosability of outer planar graphs and odd wheel is discussed.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.232-238
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• 2000

The new collimation testing technique of a white light beam using vernier Moire fringes of two line or circular gratings with different pitches is presented. We can visually measure the defocusing ($\Deltaf$), the divergence angle ($\theta$), and the longitudinal chromatic aberration $(L_{ch})$ of a collimating lens by using the technique. For example, we obtained $\Deltaf$= 21.9 mm and $\theta=0.0038^{\circ}$ for a testing lens with the focallengthf = 120.0 mm and F-number of F/2.4. The longitudinal chromatic aberration $L_{ch}$ of another testing lens withf = 65.0 mm, F/1.6, and the Abbe number V = 64.1 for the incident wavelengths of $\lambda_1=480 nm and \lambda_2=640 nm$ is easily measured by same technique. It is found that the measured value $L_{ch}=1.59mm(\pm0.01mm)$ is well agreed with $L_{ch}=1.58mm(\pm0.01mm)$ obtained by the autofocus method.