• International Journal of Highway Engineering
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• 제15권4호
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• pp.177-186
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• 2013

PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

• International Journal of Highway Engineering
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• 제18권4호
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• pp.77-82
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• 2016

PURPOSES : This paper proposes a reliability index for the safety evaluation of freeway sections. It establishes a reliability index as a safety surrogate on freeways considering speeds and speed dispersions. METHODS : We collated values of design elements including radii, curve lengths, vertical slopes (absolute values), superelevations, and vertical slopes from seven freeway sections in Korea. We also collected data about driving speeds, traffic accidents, and their deviations. We established a reliability index using these variables. RESULTS : The average radii, curve lengths, and superelevations are highly correlated with the incidence of traffic accidents. Deviations in radius and curve lengths show an especially high correlation. The reliability index, derived from speed and speed dispersions of the seven freeway sections, also correlated highly with accidents with a correlation index of 0.63. CONCLUSIONS : Since the reliability index obtained from speed and speed dispersions are highly correlated with traffic accidents, we conclude that a reliability index can be a safety surrogate on freeways considering speeds and speed dispersions together in terms of design and operational levels.

• Journal of Korean Society of Transportation
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• 제22권7호
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• pp.25-32
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• 2004

It is implicated in the current road design manual that design speed is well representing the operating speed of drivers. On the contrary, the disparity between the design speed and operating speed means that current road design cannot guarantee the safety and comfort of driving. In this context, operating speed was observed at the two lane rural roadways to find out the relation of operating speed and design speed. In addition to this, the friction factor from supply and demand which was derived from the operating speed was compared in terms of the dynamics in driving safety factor. It was concluded that the actual speed was consistently exceeding the design speed at the horizontal curves having the radius less than or equal to 200 m. Similarly, the demanded side friction was also consistently exceeding the supplied side friction at the horizontal curves having the radius less than or equal to 200 m and the amount of difference was also inversely proportional to the radius of the horizontal curves.

• Journal of the Korean Society for Precision Engineering
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• 제19권7호
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• pp.88-96
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• 2002

High-speed machining is one of the most effective technologies to improve productivity. Because of the high speed and high feed rate, high-speed machining can give great advantages for the machining of dies and molds. This paper describes on the improvement of machining accuracy in high-speed machining. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on machining accuracy is investigated using two-way factorial design.

• Journal of the Korean Society for Railway
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• 제5권3호
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• pp.142-147
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• 2002

This paper proposes the Systematic Design Methodology of the Korean High Speed Train. High Speed Train does not operate in isolation and is a part of a rail system which is influenced through input and output effects from the environment and from the neighbouring system. To fullfil its overall desired function, such input and output relationships between the systems must be considered in the system boundary conditions. Therefore, the overall interrelationship of all these effects has to be carefully considered during the design process. Here proposed methodology may provide a guide line and criteria for the systematic problem solving method of that highly complex High Speed Train System.

• Design & Manufacturing
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• 제14권4호
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• pp.46-51
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• 2020

The purpose of this study was to analyze the change in tensile strength characteristics of the weld when the welding speed and rotational speed of the tool, which are representative variables of the friction stir welding process. The equipment used in the experiment was Machining Center No. 5. The material used in the experiment is an AA6061-T6 alloy, and a rolled plate with a thickness of 2mm was used. Two experimental variables were selected, the welding speed of the tool and the rotational speed of the tool. The experimental conditions were selected in the range in which a healthy weld could be obtained through a preliminary experiment. The welding speed of the tool was increased to 100mm/min, 200mm/min, and 300mm/min, and the rotational speed of the tool was increased to 1000rpm, 2000rpm, and 3000rpm. As a result of the experiment, the tensile strength increased as the rotational speed of the tool changed at each tool welding speed. In addition, as the welding speed of the tool increased, the tensile strength of the weld was increased. The condition with the highest tensile strength of the weld was found to be a tool feed speed of 300 mm/min and a tool rotation speed of 3000rpm.

• International Journal of Highway Engineering
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• 제16권5호
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• pp.83-90
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• 2014

PURPOSES : The purpose of this study is to identify the factors affecting the effectiveness of speed limit change that is defined as the amount of increased travel speed. METHODS : A ordered logit model was adopted to analyze the relationship between the change in travel speed and contributing factors. A stretch of Kyungbu freeway was selected for the analysis because the Korea expressway corporation has raised speed limit from 100km/h to 110km/h since September 1st in 2010. RESULTS : The results showed that geometric design elements, speeding cameras, and section length were identified as factors contributing the effectiveness. Contributing geometric design elements include the number of horizontal curves and vertical curves that do not meet the design requirement with 110km/h speed limit. CONCLUSIONS : The outcome of this study will be used for establishing various traffic operations and control strategies for freeway speed management.

• Proceedings of the KSR Conference
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1195-1200
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• 2008

The railway bridge design specification used in our country at present, is reflected results that take into account link between vehicle and roadbed according to decision of TGV vehicle style in 1994, and executes design verification. Hereafter, the particular loading condition and the design speed of the high-speed EMU that is recognized to the next generation of high speed railway, are plain difference with TGV vehicle style decided in 1994. The effect that these load and design speed get in roadbed, especially superstructure, displays difference with the existent high speed railway. The goal of this study is to choose the suitable bridge type, and to reduce the construction cost for the next generation of railway, i.e., the high-speed EMU.

• Wind and Structures
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• 제19권3호
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• pp.271-294
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• 2014

The impact of artefacts in archived wind observations on the design wind speed obtained by extreme value analysis is demonstrated using case studies. A signpost protocol for detecting candidate artefacts is described and its performance assessed by comparing results against previously validated data. The protocol targets artefacts by exploiting the serial correlation between observations. Additional "sieve" algorithms are proposed to identify types of correctable artefact from their "signature" in the data. In extreme value analysis, artefacts displace valid observations only when they are larger, hence always increase the design wind speed. Care must be taken not identify large valid values as artefacts, since their removal will tend to underestimate the design wind speed.

• Proceedings of the KSR Conference
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.83-94
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• 1999

This study is about design of vehicle for air tightness to pressure waves of high speed train. When the train runs to high speed over 300km/h, the comfort of passenger come down due to difference pressure between inside and outside of passenger room. The car-body was carried out the design of air-tightness, and the analysis of inside pressure of vehicle in tunnel by TG_TUN of ALSTOM Co. The result of analysis should be used the design of air pressurized system and car-body of G7 high speed train project.