• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1587-1591
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• 2009

Safety of railroad is result of reliability which is received from test & evaluation of system. Railroad system is consisted of various sub system such as vehicle, supply of electric power, signal, communication, rail track construction, operation. To secure safety of railroad, evaluation about parts, assembly, sub system, whole system etc.. that compose railroad is essential. In this paper, I wish to describe for results that analyze korean tilting vehicle's derailment coefficient developed by national research achievement. Result that evaluation korean tilting vehicle's running safety, verified that secure even if speed-up 30 km/h than operating speed of present in curved track.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.993-1001
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• 2007

An analysis model has been developed to assess running safety of railway vehicle passing curves. By using ADAMS/Rail, a computer analysis has been conducted by changing various parameters according to the track conditions. Analysis results show as follows: A derailment coefficient of left wheel was increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A unload rate of left wheel was also increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A wear number of left wheel was increased according to increase of cant at all speed, but only at 35 m/s, it was decreased as increase of cant. A friction coefficient of left wheel was Increased according to increase of cant at all speed, but only at 35 m/s. it was decreased as increase of cant.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.147-154
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• 2013

PURPOSES: To analyze the specific factors of drivers behaviors that amount of cause the greenhouse gas emissions per vehicle. METHODS: Drivers behaviors at intersections are analyzed on the conditions of acceleration and deceleration. RESULTS : First, it is resulted greenhouse gas emissions per vehicle is produced more at intersections than at the main lines of highway. Second, it is resulted that the average speed, the average acceleration rate and the maximum speed are three major factors to produce greenhouse gas per vehicle in acceleration sections. Third, it is resulted that rapid deceleration 20m before entering intersections is the major factor to produce greenhouse gas per vehicle in deceleration sections. CONCLUSIONS: At intersections, sudden acceleration and deceleration is not good for greenhouse gas emissions. Thus, and the average speed, the average acceleration rate and the maximum speed are the chosen as factors to be controlled for drivers' behavior to reduce vehicles' greenhouse gas at intersections.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.58-64
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• 2007

As the concerns regarding global worming were increased, the pressure of greenhouse gas(GHG) emission reduction on mobile source was also increased. Carbon dioxides contribute over 90% of total GHG emission and the mobile source occupies about 20% of this $CO_2$ emission. Therefore automotive exhaust is suspected to be one of the major reasons of the rapid increase in greenhouse effect gases in ambient air. In this study, in order to investigate $CO_2$ emission characteristics from gasoline passenger cars(PC), which is the most dominant vehicle type in Korea, 106 vehicles were tested on the chassis dynamometer. $CO_2$ emissions and fuel efficiency were measured. The emission characteristics by displacement, gross vehicle weight, vehicle speed and CVS-75/vehicle speed mode were discussed. Test modes were vehicle speed modes and CVS-75 mode that have been used to develop emission factors and to regulate for light-duty vehicle in Korea. It was found that $CO_2$ emissions showed higher large displacement, heavy gross vehicle weight, low vehicle speed and CVS-75 mode than small displacement, light gross vehicle weight, high vehicle speed and vehicle speed mode, respectively. From these results, correlation between $CO_2$ emission and fuel efficiency was also determined. The results of this study will contribute to domestic greenhouse gas emissions calculation and making the national policy for climate change.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.443-446
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• 2002

A vehicle oversteered or cornering at excessive speed leaves tire yaw mark on the road surface. A yaw mark is a sign that the tire was sideslipping and exceeded its frictional limit because of centrifugal force. Problems exist with the traditional equation, “critical speed formula (CSF)”, that limits its practical use in traffic accident reconstruction. A major problem is that the equation dose not account for vehicle dynamics and interface between tire and road. The literature refers to that the accuracy of the critical speed formula varies with several factors. New equations that account for vehicle dynamics are introduced in this paper. A comparison of the accuracy of the new method and the traditional method in the calculation of speed is conducted.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.1-10
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• 2010

Safety improvement has been a continuous challenge, especially at toll gate of express highway where traffic conflict often occurs due to frequent lane change by drivers of "Hi-pass" lane and regular "TCS" lane. As a part of research on safety at toll gate, this study videotaped traffic conflict data between vehicles using centrally located "Hi-pass" lane and regular "TCS" lane and analyzed accident risk. According to the correlation analysis of vehicle speed, relative vehicle speed, and sudden vehicle deceleration rate due to traffic conflict, when the relative vehicle speed between centrally located "Hi-pass" lane and regular "TCS" lane increases, sudden vehicle deceleration rate also increases. One of the findings is that centrally located "Hi-pass" lane at toll gate shows different location for traffic conflict, and frequency of traffic conflict and the relative vehicle speed was also different based on vehicle lane use. TA (Time to Accident) analysis shows that accident rate is high at toll gate where Hipass lane is installed in center lane, when the occurrence of sudden vehicle deceleration and deceleration time of vehicles rise for vehicles on "Hi-pass" lane. Furthermore, if the expressway entrance/exit point is closely located to toll gate, TA showed a low value. Thus, it is necessary to reduce the relative vehicle speed in order to improve safety. The Study presents reduction of the relevant vehicular speed and prevention of accidents at the centrally installed "Hi-pass" lane as an important strategy for safety improvement at toll gate.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.528-535
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• 2011

According to railway safety regulations for securing the railway vehicle's quality and performance, it can be partly exempted that the performance tests and production inspections on the railway vehicles which are produced and assembled for the purpose of test and research. The reasons of this exemption are for ensuring maximum autonomy and for saving time considered the development period of railway vehicle. However, it was continuously demanded the necessity of supplementation on the confirmation about railway vehicle's quality & performance. Therefore, we added "The monitoring step" which is for securing the quality and performance in high speed railway vehicle's subsystem & compartment to supplement those tests & inspections in development. In this paper, based on a standard ABS(Activity Breakdown Structure) of railway vehicle and a WBS(Work Breakdown Structure) of the railway vehicle system, we investigate the necessity of monitoring in the High speed railway vehicle development. And by comparing and analyzing the essential requirements of international standard, IRIS(International Railway Industry Standard) & TSI(Technical Specification for Interoperability), we try to examine a standard monitoring procedure.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.31-35
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• 2010

In this paper, a speed estimation method at coasting operation in an induction motor speed sensorless control for railway vehicle traction systems is presented. At coasting operation, there is no information obtaining rotor speed since all switches of an inverter are turned off. The inverter frequency should be synchronized with the rotor frequency for repowering at coasting condition. The proposed method injects DC current to the induction motor during a short time, then the flux angle and rotor speed needed for control can be estimated rapidly.

• Design & Manufacturing
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• v.16 no.4
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• pp.40-45
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• 2022

The EV electric vehicle market is growing rapidly worldwide. An electric vehicle means a vehicle that uses energy charged through an electricity source as power. The precision of the press is important to mass-produce the drive motor, which is a key component of the electric vehicle. The size of the driving motor is increasing, and The size of the mold is also growing. In this study, the precision of large high-speed presses for mass production of driving motors was measured. A study was conducted on the measurement method of press and the analysis of measurement data. A drive motor is a component that transmits power by converting electrical energy into kinetic energy. EV driven motors have key material properties to improve efficiency. The material properties are the thickness of the material. As a method for improving performance, use a 0.2mm thin steel sheet. Mold is also becoming larger. As the mold grows, the size of the high-speed press for mass production of the driving motor is also increasing. Also, the precision of the press is the most important because it uses a thin iron plate material. So the importance of large press precision is being emphasized. In this study, the effect of large high-speed press structure on precision was verified