• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.155-163
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• 2012

At present the letter sizes of traffic sign are variously designated as 22 cm through 60 cm, however the basis for determination has not been found so far. Driver's visual acuity for getting a driver licence is required higher than 0.5. In order to interpret the information of traffic signs effectively, the minimum requirement of driver's visual acuity must be applied to determine the letter size of traffic sign. Therefore we reviewed that a driver with visual acuity of 0.5 could read the current letter sizes of traffic sign. In addition, a methodology was developed to determine the letter size of traffic sign satisfied with the driver's visual acuity of 0.5. This study established scenarios that were composed of visual acuity, reaction time, the number of lane and the letter sizes of traffic sign for each scenario were proposed. Current letter size of traffic sign would not be difficult for drivers with minimum visual acuity of 0.5 to recognize the contents or information of traffic signs. The method developed in this research has an advantage that can consider a human factor like driver's visual acuity for the design of traffic signs. There is also a meaning of making a basis for the letter size of traffic sign.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.47-55
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• 2011

The purpose of this study was to determine the legibility distance for traffic road sign and traffic sign, fixation duration and number of fixation during the time of recognition of traffic road signs under different vision conditions. This experiment was conducted on a closed-road circuit which has realistic driving road and environment Each participant drove the real vehicle for the experiment and specially built traffic road sign for the experiment and traffic road signs on the side of closed-road circuit were used. Different vision conditions were simulated using spectacle lenses to reach visual acuity 1.0 and 0.8 and it was 1.2 without spectacles and each participant tested under 3 vision conditions.. The result of this study demonstrated that there was a significant difference on legibility distance between visual acuity of 1.2 and 0.8 and there were also significant difference on fixation duration and number of fixations with smaller traffic signs. This study demonstrated the importance of vision correction for driving at night-time, also showed there would be difference on legibility distance and efficiency of eye movement such as fixation duration and number of fixation despite of satisfied visual acuity for driver's license requirement.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.473-480
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• 2004

Recently, they are interested in the relation between night's vehicle accidents of drivers and the dynamic visual acuity at home and aboard. So, in this research, we tried to design an optical system of the inspection equipment to measure the dynamic visual acuity. A optotype standard did to Landolt's ring with 45mm of diameter and 9mm of gap to maintain the visual acuity of 1.0 in the 30m distance. An optical structure of the inspection equipment was composed of the sequence of an observer, a plus refraction lens system, a minus refraction lens system, and an optotype that was arranged to have characteristics that the size of the first virtual image of the optotype made by the minus refraction lens system grows bigger gradually according to the optotype movement to near distance from far distance, and also the first virtual image moves to the principle plane from the focal point of the plus refraction lens system as the size of the first virtual image arranged to the inside of focal distance of plus refraction lens system grows bigger gradually. As doing these processes, we completed the optical system of which characteristic is that the position of the final second virtual image moves to 3m from 50m as the size of the second virtual image made by the plus refraction lens system maintains to be regular.