• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.160-170
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• 2002

Retroreflective article is different from other reflecting objects as it returns the incidence ray to the near of its source. This characteristic makes the retroreflectors have many applications in reflective highway signs, reflective vests, and other safety-relaxed items. These articles may have various shapes. However, the quantitative evaluation of performance for the best shape of retroreflector needs much time and cost for manufacturing prototypes and for performance experiments. In this work, we have developed a program for simulating the trace of ray entered into a retroreflective element, in order to determine the optimal shape of retro-reflection. We have also proposed new performance criterion of retroreflective articles, which can confide the range of incidence angle, instead of the criterion with the merely retroreflective strength.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.101-104
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• 2007

There is no overall understanding about the road marking situation in Korean national highway nowadays. In addition road marking increases risk in traffic accidents especially while it's raining at night because of diffused reflection. So administrator has a lot of problems to maintain and make a decision about the road marking. In this paper, literature review and field investigation about the road marking are carried out from the viewpoint of road safe and the propriety in retroreflective performance of the road marking is grasped. Also, improvement methods about retroreflective performance of the road marking are proposed on the basis of the result in field investigation.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.149-163
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• 1994

A novel method of dimensional measurement using machine vision, which is called Landmark Tracking System, has been developed. Its advantages come form tracking only the bright, standard shaped "landmarks" which are made from retroreflective sheets. In the design of the LTS, it is essential to know the relationship between optical parameters and their influence on system performance. Such optical parameters include the brightness of landmark image, the illumination system design, and the choice of imaging optics. And the performance of retroreflective material also plays important role in the LTS performances. Influences of such optical parameters on LTS's dimensional measurement characteristics are investigated, with respect to the retroreflective material, the imaging optics, and the illumination system. Measuremtn errors due to parameter variations are also analyzed. Experiments are performed with a LTS prototype. Retroreflective characteristics are verified, and the LTS's measurement performances are measured in the form of repeatability and accuracy. Experimental results shgow that the LTS has repeatability better than 1/30,000 of a field of view(30 degrees), and accuracy better tha 1/3,000 of a field fo view.d fo view.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.185-194
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• 2014

This study investigates the methodology to evaluate the quantified performance of pavement markings and traffic guide signs using digital images. This methodology is significant to attempt to quantify their performance without large brightness photometer at the nighttime and bad weather. The retroreflective performance of pavement markings are evaluated through the contrast of gray levels of pavements and markings in collected digital images under the case of rain, dampness, and dryness. In addition, the appraisal of retroreflective performance of traffic guide signs are implemented through the comparison between interior illuminated and the existing retroreflective traffic guide signs using the contrast of luminance extracted from the value of RGB of backgrounds and legends in collected digital images according to geometric design, driving lanes, and the distance between the car and the sign. As a result, the retroreflective performance of pavement markings deteriorates about 3.5 times and 2 times under the case of rain and dampness respectively than dryness. Also, the performance of the existing traffic guide signs is significantly influenced by geometric design, driving lanes, and the distance, otherwise interior illuminated traffic guide signs. This methodology can be utilized to construct objective information of performance of traffic safety facilities to select appropriate position of expensive high reflective pavement markings and interior illuminated traffic guide signs considering diverse weather and geometric design.

• Journal of the Korean Society of Safety
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• v.10 no.4
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• pp.109-117
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• 1995

This study is for the development of a model to convert a set of rotational bodies into the new theoretical design for the equivalent volume transformation between the geometric angles and the specific intensity in the traffic control material system, called the retroreflection system to guide the night driver for safety. There are five new models theoretically identified with the concept of the retroreflective performance and human environment of the night driver. The new system can evaluate the design in retroreflective transportation material system with better performance, safety, and economy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.228-241
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• 2021

This study verified the performance change of a LiDAR when it detects road signs, which are potential cooperation targets for an autonomous vehicle. In particular, road signs of different colors and materials were produced and tested in controlled rainfall on the real road environment. The NPC and intensity were selected as the performance indicators, and a T-Test was used for comparison. The study results show that the performance of LiDAR for the detection of road signs was reduced with the increase of rainfall. The degradation of performance in retroreflective sheets was lesser than painted road signs, but at the amount of 40 mm/h or more, the detection performance of retroreflective sheets deteriorates to an extent that data cannot be collected. The performance level of black paint was lower than that of other colors on a clear day. In addition, the white sheet was most sensitively degraded with the increase in precipitation. These performance verification results are expected to be utilized in the manufacturing of road facilities that improve the visibility of sensors in the future.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.3
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• pp.537-547
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• 2017

This study evaluates the wearing performance of a self-contained breathing apparatus (SCBA) belt for firefighters in Korea. A SCBA belt design was suggested based on the wearing evaluation of a SCBA belt; subsequently, prototypes I and II were created. A wearing evaluation of prototypes with improved design and design preference was performed. Six designs elements of the SCBA belt for firefighters were suggested based on the survey results of wearing the SCBA belt and for the SCBA belt design preference for use by firefighters. First, belt material should be made of black high-strength aramid textiles. In addition, Velcro should be used to attach and detach retroreflective and fluorescent materials along with various colors for visibility. Second, the chest belt should be made of the same material used for other parts; in addition, the chest belt should be moved to the center for center of gravity and a cobra buckle should be applied. Third, an O-ring should be applied to the back and the belt connected to the O-ring should distribute the weight in six axes. Fourth, a detachable air respirator should be able to separate by using upper and lower cobra buckles. Fifth, a separable leg belt and a detachable pocket are also suggested. Sixth, a ring for walkie-talkies, alarms and equipment as a fabric ring are also suggested. Prototype III with an improved design was created based on the results of the design suggestion.

• Elastomers and Composites
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• v.46 no.4
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• pp.277-283
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• 2011

In this study, engineering grade and high intensity reflective sheets were prepared with glass beads and their reflection performance and physical properties were investigated. The reflective sheets prepared by using glass beads are divided into enclosed or encapsulated lens type, depending on whether the glass beads are open in air or not. Because of an extra layer on the glass bead surface, the enclosed lens type reflective sheets show very little change in the properties by bad weather conditions, compared to encapsulated lens type reflective sheets. Optimization of the amount of glass beads on the surface was carried out, which determines the retroreflective properties. Enclosed and encapsulated lens type reflective sheets with various colors were prepared and their coefficients of retroreflection were determined. The encapsulated type reflective sheet with white color shows a coefficient of retroreflection of $210.4cd/1x{\cdot}m^2$, which is higher than the enclosed type ($74cd/1x{\cdot}m^2$). Effect of washing on the reflective property and adhesive power of the reflective sheets was investigated, and it is found that the number of glass beads decreased with washing and the aluminum layer deposited was damaged extensively in the encapsulated lens type reflective sheets.