• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.7-19
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• 2007

The purpose of posted speeds is to provide a speed that ensures the safety of vehicle flow according to given road situations. Because of this, posted speeds must be carefully examined, and posted speeds at freeway exits and entrances in particular should consider car characteristics. Posted speeds at freeway exits and entrances must take changing speeds due to curve radiuses into consideration and in this study, an 85th percentile speed becomes the most important element to consider. When it is considered that most traffic accidents occur because of variations in speed between cars, posted speeds should be set after considering car traveling characteristics. Within these dimensions, instead of putting significance on an upper direction regulation or lower direction regulation, speed distributions which fit to the characteristics of each road should be fully considered. Accordingly, this study evaluated appropriate posted speeds that will reduce the dangers of traffic accidents through posted speed regulations of roads now in operation by offering a posted speed setting method theory, using entries at Yangji, Yongin, and Cheongwon interchanges as subjects.

• Journal of Korean Society of Transportation
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• v.23 no.7 s.85
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• pp.35-42
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• 2005

Few studies have been carried out to find out the interaction of design speeds, operating speeds, and posted speeds though they have a complementary relationships. As an attempt to find the relationships, this study measured the speeds of the free flowing vehicles at four lane rural highways. In comparison of 95th percentile speeds and inferred design speeds determined from the road design manual with the geometric features of each sites, operating speeds were constantly higher than the inferred design speeds at the sites where the inferred design speed is under 110km/h. and the reverse situation was observed at the sites where the inferred design speed is over 130km/h. In the comparison of operating speeds and posted speeds. the range of the 85th percentile speeds at the sites where posted speeds is 80km/h was distributed from 95km/h to 110km/h. and the range was distributed from the 105km/h to the 120km/h at the sites where posted speeds is 90km/h. Multiple regression analysis was used to develop prediction equations for mean. 85th. and 95th percentile speeds at approach and curve midpoint locations. At the midpoint, only posted speeds influenced the mean, 85th. At the approach locations, the mean, 85th, 95th percentile speeds were influenced by posted speeds and length of the approach tangent.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.49-57
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• 2010

This case study investigated red light violations at CBD, suburban and rural signalized intersections in chungbuk. The goal of this study is to understanding the collection between red light violations and various driver, vehicles and environmental factors. This study uses descriptive statistics analysis and logistics analysis with SPSS 12.0 software. The major results of this study are as follows. First, red light violations occurred at rural and CBD more than suburban area. Second, About 81.1% of the violators were traveling at or below the posted speed limit. Moreover, 77.3% of the violations occurred within 2 seconds after the on set of red light. Finally, the logistic regression model, which is statistically significant(chisquare=0.000, McFadde=0.265)was developed, and includes the local type(CBD/suburban/rural), violators' gender, season, vehicle type, time of day, vehicle speed as the independent variables. In this study did not find significant relationship between red light violators' age and their driving behavior approaching signalized intersections.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.187-196
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• 1999

The increasing interest in the use of Automated Speed Enforcement (ASE) systems in Korea enables to enforce speed violation by National Police Agency. We have analyzed the mechanism of ASE systems on traffic safety throughout Korea. 1 The data collected on a 2km road-section of each 32 ASE stations during one rear period indicate significant safety improvement. The results were (a) a decrease in the total number of accidents of 28%, (b) a decrease in the number of fatalities of 60%. 2. The study also that ASE systems are effective to reduce average speed, speed variance, and short headway. 3. Based on the operational data collected at 15 locations, an aggregate safety prediction model is proposed as a multiple regressions form. The primary operational variables that appear to affect the frequencies of accident are : average speed, speed variance, and the number of vehicles exceeding 30km/h of posted speed limit.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.56-62
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• 2017

Although most electricity production contributes to air pollution, the vehicle organizations and environmental agency categorizes all EVs as zero-emission vehicles because they produce no direct exhaust or emissions. Currently available EVs have a shorter range per charge than most conventional vehicles have per tank of gas. EVs manufacturers typically target a range of 160 km over on a fully charged battery. The energy efficiency and driving range of EVs varies substantially based on driving conditions and driving habits. Extreme outside temperatures tend to reduce range, because more energy must be used to heat or cool the cabin. High driving speeds reduce range because of the energy required to overcome increased drag. Compared with gradual acceleration, rapid acceleration reduces range. Additional devices significant inclines also reduces range. Based on these driving modes and climate conditions, this paper discusses the performance characteristics of EVs on energy efficiency and driving range. Test vehicles were divided by low / high-speed EVs. The difference of test vehicles are on the vehicle speed and size. Low-speed EVs is a denomination for battery EVs that are legally limited to roads with posted speed limits as high as 72 km/h depending on the particular laws, usually are built to have a top speed of 60 km/h, and have a maximum loaded weight of 1,400 kg. Each vehicle test was performed according to the driving modes and test temperature ($-25^{\circ}C{\sim}35^{\circ}C$). It has a great influence on fuel efficiency amd driving distance according to test temperature conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.593-596
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• 2018

The speed of vehicles has remained a significant factor that influences the severity of accidents and traffic accident rate in many parts of the world including South Korea. This behavior where drivers drive at speeds which exceed a posted safe threshold is known as 'speeding'. Over the past twenty years, the Korean National Police Agency (NPA) has become aware of an increased frequency of drivers who are speeding. Therefore, fixed-type ASE systems [1] have been installed on hazardous road sections of many highways. These system monitor vehicle speeds using a camera. However, the use of ASE systems has changed the behavior of the drivers. Specifically, drivers reduce speed or avoid the route where the cameras are mounted. It is not practical to install cameras at every possible location. Therefore, it is challenging to thoroughly explore the location where speeding occurs. In view of these problems, the author of this paper designed and implemented a prototype visualization system in which point and color are used to show vehicle location and associated over-speed information. All of this information was used to create a comprehensive visualization application to show information about vehicle driving. In this paper, we present an approach detecting vehicles moving at speeds which exceed a threshold and visualizing the points those violations occur on a map. This was done using vehicle trajectory data collected in Daegu city. We propose steps for exploring the data collected from those sensors. The resulting mapping has two layers. The first layer contains the dynamic vehicle trajectory data. The second underlying layer contains the static road networks. This allows comparing the speed of vehicles on roads with the known maximum safe speed of those roads, and presents the results with a visualization tool. We also compared data about people who drive over threshold safe speeds on each road on days and weekends based on vehicle trajectories. Finally, our study suggests improved times and locations where law enforcement should use monitoring with speed cameras, and where they should be stricter with traffic law enforcement. We learned that people will drive over the speed limit at midnight more than 1.9 times as often when compared with rush hour traffic at 8 o'clock in the morning, and 4.5 times as often when compared with traffic at 7 o'clock in the evening. Our study can benefit the government by helping them select better locations for installation of speed cameras. This would ultimately reduce police labor in traffic speed enforcement, and also has the potential to improve traffic safety in Daegu city.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.51-61
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• 2007

Increasing traffic volumes and excessively high speeds on national highways through small towns often increases the frequency of accidents. Extensive paved areas, narrow sidewalks, median barriers and little greenery have resulted in a dangerous and destructive living environment for residents. The reason for this problem is that throughways were expanded without considering the harmony between the throughways and the small towns. Construction of bypasses and reclassification of highway functions would solve the problem by reducing vehicle speeds in small towns, but this method is too costly and time consuming. Therefore, this study analyzes national highways through small towns as a case studies using positive guidance in order to improve safety and develop alternatives. As a result of the case study, the biggest problem was observed to be the excessively high vehicle speeds, This study also identified places were information should be given or posted but is currently absent. Therefore, this study concludes that notional highways through small towns need installation of speed reduction facilities and additional information provision to drivers.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.490-502
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• 2012

The use of recycled aggregate, even for low-performance concrete, has been very limited because recycled aggregate, which contains a large amount of old mortar, is very low in quality. To produce a high-quality recycled aggregate, removing the paste that adheres to the recycled aggregate is very important. We have conducted research on a complex abrasion method, which removes the component of cement paste from recycled fine aggregate by using both a low-speed wet abrasion crusher as a mechanical process and neutralization as chemical processes, and well as research on the optimal manufacturing condition of recycled fine aggregates. Subsequently, we evaluated the quality of recycled fine aggregate manufactured using these methods, and tested the specimen made by this aggregate. As a result, it was found that recycled fine aggregates produced by considering the aforementioned optimal abrasion condition with the use of sulfuric acid as reactant showed excellent quality, recording a dry density of 2.4 and an absorption ratio of 2.94. Furthermore, it was discovered that gypsum, which is a reaction product occurring in the process, did not significantly affect the quality of aggregates. Furthermore, the test of mortar using this aggregate, when gypsum was included as a reaction product, showed no obvious retarding effect. However, the test sample containing gypsum recorded a long-term strength of 25.7MPa, whereas the test sample that did not contain gypsum posted a long-term strength of 29.4MPa. Thus, it is thought to be necessary to conduct additional research into the soundness and durability because it showed a clear reduction of strength.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.95-105
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• 2002

Under a specific roadway alignment condition by design-speed standards, safety of the roadway is determined by an actual operating speed of a driver. This research takes first lanes of four-lane(hi-direction) rural highways as target facility. It also takes the straight and curved lanes of the selected highways for in-depth study. This study used NC-97 to detect speeds of passenger cars whose speeds are not affected by front vehicles. This research analyzed properties of 85th percentile operating speed at upstream of horizontal and through curves under various alignment conditions. The results show that 53∼65 Percent of drivers drive faster than the posted speed-limit (80KPH) by 14∼20 KPH on average. It also shows that the 85th-percentile operating speeds are the lowest at the middle point of curve length when curve radius is smaller. However, they are lowest at 1/4 point of curve length when curve radius is greater. Along roadways where curve radius is small, difference between upstream speed and the speed along the curve is considerably large. On the other hand. the speed difference is setting smaller as the curve radius is increasing. According to the results, significant variables affecting the 85th percentile operating speeds are curve radius and the 85th-Percentile operating speeds of upstream curves.

• Journal of Distribution Science
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• v.15 no.9
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• pp.85-93
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• 2017

Purpose - The volume and valence of online word-of-mouth(eWOM) have become an important part of the retailer's market success for a wide range of products. This study aims to investigate how the growth of eWOM has generated the product's final financial outcomes in the introductory period influences. Research design, data, and methodology - This study uses weekly box office performance for 117 movies released in the South Korea from July 2015 to June 2016 using Korean Film Council(KOFIC) database. 292,371 posted online review messages were collected from NAVER movie review bulletin board. Using regression analysis, we test whether eWOM incurred during the opening week is valuable to explain the last of box office performance. Three major eWOM metrics were considered after controlling for the major distributional factors. Results - Results support that major eWOM variables play a significant role in box-office outcome prediction. Especially, the growth rate of the positive eWOM volume has a significant effect on the growth potential in sales. Conclusions - The findings highlight that the speed of eWOM growth has an informational value to understand the market reaction to a new product beyond valence and volume. Movie distributors need to take positive online eWOM growth into account to make optimal screen allocation decisions after release.