• Journal of dental hygiene science
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• v.10 no.1
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• pp.45-54
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• 2010

The purpose of this study was to offer the importance on factors of selecting dental institution according to general characteristics targeting general dental patients, and the information of having important influence upon choosing dental clinic and dental hospital. The survey was carried out from August 2009 to September. As a result of analyzing SAS(ver 9.1), the following conclusions were obtained. In the importance on factors of selecting dental institution according to general characteristics, it was thought to be important in convenience of movement or mobility such as distance, transportation, and parking convenience according to age level. According to final academic background, the importance in a factor of rumor in dental clinic was high(p < 0.05). According to job, the significant difference was shown in rumor of dentistry and parking convenience(p < 0.05). According to income, the factor in the appearance of training a medical specialist was indicated to be statistically higher in the group with over 5 million won than the group with under 2 million won(p < 0.05). Given seeing the distribution of opinion about dental hospitals (comparison with dental clinics), the excellence in the medical staff's ability was indicated to be the highest in all of the factor of influencing the use satisfaction(${\beta}=0.18$), the factor of influencing the recommendation level(${\beta}=0.21$), and the factor of influencing the re-use intention(OR=2.09).

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.131-140
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• 2012

Lane markings such as edgelines, centerlines, and lines that delineate lanes generally provide drivers with the various information for safe driving. Drivers can easily recognize the lane markings through the color differences between the markings and road surfaces during the daytime. However, it is a bit difficult for drivers to perceive them during the nighttime due to the lack of artificial lights. Although the glass beads with the 1.5-refractive index have been used to improve the visibility of the lane markings during the nighttime, it is still difficult for drivers to recognize the lane markings properly, especially during the rainy nighttime, which may often lead to traffic accidents. To improve the retroreflectivity and visibility of the lane markings during the rainy nighttime, the high refractive beads with the 2.4-refractive index are essentially required, but they do not work appropriately during the dry nighttime. Thus, the mixed materials with the 1.5, 1.9, and 2.4-refractive beads should be considered for the satisfactory implementation of the lane markings. This study reveals the best mixing rates of the beads by conducting benefit-cost analysis under various weather conditions in Korea. The analysis results show that the lane markings with the 100% of the 2.4-refractive beads provide the highest visibility of lane markings regardless of the roadway conditions, but the benefit-cost (B/C) ratio of the bead mixture is merely 0.46. The best mixing rate of the beads, from the highest B/C ratio viewpoint, was identified as the mixture with a 80% of 1.5-refractive beads and a 20% of 2.4-refractive beads. Some limitations and future research agenda have also been discussed.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.55-61
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• 2012

Road signs are important facilities in terms of providing information to driver, they are helpful for driver's judgment as deliver it's own information. However if there is occurrence dew on the road sign because of the change of temperature and humidity, it can be cause of accidents. Therefore it is necessary to develop anti-dew or dew resistance technology. In this research the anti-dew technologies such as insulation road sign and anti-dew film were compared with normal road sign, and the effectiveness analysis was conducted for each alternatives. The quantity of dew on the road sign was check using ANOVA and Tukey HSD and the relation between the retro-reflectivity and quantity of dew on the sign was check using Pearson correlation coefficient. As a result, the sample of anti-dew film attached road sign showed lesser quantity of dew compared with normal road sign. After 90 seconds, the difference of dew quantity for anti-dew film and insulation road sign showed statistically significant result. The relation of between quantity of dew and retro-reflectivity was inverse correlation. As a result, when analyzed the quantity of dew and retro-reflectivity a point of view anti-dew effectiveness, the anti-dew film and insulation road sign showed meaningful result.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.185-201
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• 2018

Road lighting is highly preferred as the major nighttime road safety countermeasures. When it comes to the pole-type road lighting, as it's installed at a certain height from the road surface, the driver is dazzled by the light source, interrupting the driver's visibility and furthermore, the light leaks to the area outside the road boundary, worsening the energy efficiency as well as generating the light pollution to the surrounding environment including the animals and plants. The study developed the low-level lighting systems, so it is possible to prevent the lights from being strayed, so there is no any side effects in terms of the sleep deprivation. The study compared the performance as the lightings between low-level lightings and conventional pole based lighting systems. As the results, the low-level lighting systems showed the higher performance in terms of average surface luminance, uniformity, glare compared to the conventional lighting systems.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.525-532
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• 2022

The port of Mokpo operates the largest number of coastal passenger ships and routes in Korea. These coastal passenger ships pass through narrow channels in the south-west coast of Korea owing to the geographical effect. It is difficult to find a research for the safety of the marine traffic environment in the narrow channel used by coastal passenger ship. Therefore, in this study, the navigation safety of the target coastal passenger ship was analyzed in the narrow channel near the port of Mokpo using the Korea design standard for port and harbour facilities. As a result of the analysis, the width of the narrow channel between Maek-island and Dali-island is narrower than 1.5 times of the target ship's length over all, the degree of curvature of the narrow channel exceeds the standard value of 30°, and several fishing gears exist near the narrow channel. Finally, the following were suggested to improve the safety of navigation on the narrow channel: keeping one-way traffic during the day-time, and navigating through the designated fairway during night·visibility restriction·low tide.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.44-53
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• 2023

Recently, serious parking problems are occurring due to the difficulty of securing sufficient parking space, and it may lead to other traffic or social problems. In order to solve the parking problem in areas and districts beyond a certain range, a study on-roads and off-street parking lots reflecting regional characteristics is necessary. Therefore, this study establishing a parking demand calculation model for use as a basic study in establishing on-road and off-road characteristics. In order to conduct the study, Dong-fu, Daegu Metropolitan City was divided into dongs, and parking facilities and parking demand were investigated. The survey time was divided into daytime and nighttime on weekdays, and the types of vehicles were divided into three types: passenger car, small trucks and buses, large trucks and buses. As explanatory variables for calculating parking demand, the total floor area of buildings for each of six purposes was used, including detached houses, apartment houses, neighborhood living facilities, cultural and assembly facilities, business facilities, and sales facilities. As a result of the correlation analysis, among the six explanatory variables, the total area of neighborhood living facilities showed a significant correlation with on- and off-street parking demand. A regression analysis model was constructed using the total area of neighborhood living facilities as an explanatory variable, and statistically significant results were obtained.

• Sleep Medicine and Psychophysiology
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• v.10 no.2
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• pp.93-99
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• 2003

Objectives：Sleep loss and excessive daytime sleepiness may have serious consequences, including traffic and industrial accidents, decreased productivity, learning disabilities and interpersonal problems. Yet despite these adverse effects, there are few epidemiological studies on sleep loss and daytime sleepiness in the general population of Korea. This study investigates the number of people who suffer from sleep insufficiency, how much recovery sleep occurs on weekends, and the relationship between the amount of recovery sleep and daytime sleepiness. Methods：A total 164 volunteers, aged 20 and over, were recruited by advertisement. The subjects were workers and college students living in Seoul, Korea. Subjects were excluded if they were aged over 60；if they had medical, neurological, psychiatric or sleep disorders that could cause insomnia or daytime sleepiness；if they were not following a regular sleep schedule；if they traveled abroad during the study；or if they did not leave home to work or were shift workers. They were interviewed and given a sleep log to complete on each of 14 consecutive mornings. They also completed the Epworth Sleepiness Scale (ESS) at noontime on the last day of the second week. All statistical data were analyzed by t-test, $X^2$-test or ANOVA, using SPSS/PC+. Results：The results showed that the subjects woke up at 6：50 (${\pm}1$：16) on weekdays, 7：09 (${\pm}1$：29) on Saturdays, and 8：12 (${\pm}1$：39) on Sundays and holidays. They took more frequent and longer naps on Sundays than on weekdays and Saturdays. The mean sleep duration was 6h 35 min. on week nights, with a mean increase of about 1h on weekends. Only 9.1% of the subjects spent more than 8h in bed on week nights, with 67% spending less than 7h, and 49.4% reported recovery sleep of more than 1h on Sundays. The subjects who reported recovery sleep of more than 2h on Sundays, showed significantly more excessive daytime sleepiness than those who reported less than 30 min (F=2.62, p<.05). Conclusions：These findings suggest that sleep insufficiency and excessive daytime sleepiness are relatively common in Korea, and that the people who get insufficient sleep on weekdays try to compensate for sleep loss with oversleeping and daytime napping on Sundays and holidays. It appeared that daily sleep insufficiency had a cumulative effect and increased daytime sleepiness.

• Journal of Environmental Impact Assessment
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• v.28 no.2
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• pp.113-128
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• 2019

The concentration and coating thickness of black carbon (BC) were measured along with fine dust in the fall of 2018, at the Seoul Metropolitan Area Intensive Monitoring Station (SIMS). In fall, the concentration of $PM_{10}$ and $PM_{2.5}$ was $23{\pm}12.6{\mu}g/m^3$ and $12{\pm}5.8{\mu}g/m^3$, respectively, lower than that in other seasons. The BC level, measured using an Aethalometer, was $0.73{\pm}0.43{\mu}g/m^3$, while the levels of elemental carbon (EC) and refractory-BC (rBC), measured by semi-continuous carbon analyzer (SOCEC) and single particle soot photometer (SP2), were $0.34{\pm}0.18{\mu}g/m^3$ and $0.32{\pm}0.18{\mu}g/m^3$, respectively. As such, the concentration level differed according to the measurement method, but its time-series distribution and diurnal variation showed the same trends. The BC concentration at SIMS was primarily affected by automobiles with higher levels of BC during morning and evening commuting times due to increased traffic congestion. rBC, measured by SP2, had a peak concentration and coating thickness of 84 nm and 43 nm, respectively. Notably, the coating thickness had an inverse relationship with particle size.