• Proceedings of the KSR Conference
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• 2002.05a
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• pp.344-350
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• 2002

This paper proposes the Systematic Design Methodology of the Korean High Speed Train. High Speed Train do not operate in isolation and are part of a rail system which is influenced through input and output effects from the environment and from the neighbouring system. To fulfil 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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.29-35
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• 2010

Recently the industry high-speed machining has been applied to the automotive, aircraft, electronics parts machining because the effect of cost savings, machining time reduction and productivity improvement. In this study recently the aircraft structural aluminum alloy 7075 used in cutting the ball end-mill on the surface roughness terms most affect the parameters of the spindle speed and feed rate on the surface roughness of the work-piece according to the cutting depth is to investigate. Cutting depth at 0.3 mm has the lowest surface roughness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.20-25
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• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2207-2212
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• 2008

The next generation of Korean high-speed train under development will be designed for the maximum operating speed of 350km/h and maximum speed of 400km/h. This high-speed operation may cause the noise and vibration problems around tunnel exit due to the higher micro-pressure wave than present level. In this study, the nose shape optimization was conducted for the countermeasure against these problems. Axi-symmetric solver was used for numerical simulation, and response surface was used for efficiency of optimization process. Also the multi-step optimization was conducted to find out more accurate optimal shape. Through these analysis and optimization, it was found out that the optimal nose shapes for minimization of micro-pressure wave are definitely different along the nose length variation. And the mechanism of micro-pressure wave reduction was closely investigated by the analysis of generation process of compression wave in tunnel. The results are expected to be used as design guideline for performance improvement of the next generatin of Korean high-speed train.

• Steel and Composite Structures
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• v.37 no.4
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• pp.493-501
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• 2020

The paper describes an optimization method based on the mathematical model of interaction within multibody 'bridge-track-cars" dynamic system. The interaction is connected with considerable dynamic phenomena influenced by high traffic speed (up to 400 km/h) on high-speed railroads. The trend analysis of a structure is necessary to determine the direction and resource of optimizing the system. Thus, scientific methods of decision-making process are necessary. The process requires a great amount of information analysis dealing with behavior and changes of the "bridge-track-cars system" that consists of mechanisms and structures, including transitions. The paper shows the algorithm of multi-criteria optimization that can essentially reduce weight of a bridge superstructure using big data analysis. This reduction is carried out in accordance with the constraints that have to be satisfied in any case. Optimization of real steel-concrete beam is exemplified. It demonstrates possibility of measures that are offered by the algorithm.

• Design & Manufacturing
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• v.10 no.3
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• pp.46-50
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• 2016

Laminate products for motor core are developed with a structure in which the importance of quality level and clamping force is influenced by the recent performance and safety of the product. It has been confirmed that the accuracy of the mold is emphasized, and that the accuracy of the tightening force produced by the stacked product for the motor core is greatly influenced by the change in the bottom dead center displacement of the aged high speed press. The reason why setting the mold, and test the effect of bottom dead center of high speed press is to improve product pull force in embossing process at mold. We have applied the system to minimize the effect on the damping displacement under the dynamical degree of the equipment by applying the emboss complement device which can test the influence and complement in the process.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.46-50
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• 2003

The horizontal fillet joint is one of the most important weld joints in the shipbuilding industry. High-speed rotating arc welding, which can increase the leg length, is an effective way to improve the weld productivity and quality for the horizontal fillet welding. Based on the Taguchi method, the effects of welding parameters on bead characteristics - leg length, asymmetry, undercut, overlap - are investigated fur high-speed welding process. As a result, the adequate welding parameters are selected for the required leg length, symmetric bead and no undercut. Besides, considerably consistent leg length is observed for the horizontal fillet welding with gap variation up to 3mm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.2
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• pp.5-13
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• 2003

In this study, experiments of high speed grinding had been earned out in a STD11 specimen for evaluating the grindability with designed CBN grinding wheels Ground surfaces were analyzed and evaluated by means of surface Integrities and wheel damages. The surface roughness and 3 dimensional profile had been used for analyzing the micro-surface integrity. The residual stress of the ground surface had been measured by the x-ray diffraction method. Also, the surface state of the ground specimens and the grinding wheels were evaluated by a metallurgical microscope and SEM system after high speed grinding in order to choose the suitable machining conditions.

• Journal of Korean Society for Quality Management
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• v.30 no.2
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• pp.160-180
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• 2002

This is an exploratory research to examine the high-speed Internet access service's quality There are relatively scanty studies on telecommunication service quality such as the high-speed Internet access service. It has long been considered that service qualify are composed of process quality and outcome quality. Conducting an empirical research, we proposed that traditional outcome quality should be segmented with technical quality and outcome quality. Outcome quality is related to meeting consumer's needs to seek terminal value. In this paper, we explore to diagnose the well-known SERVQUAL's applicability to telecommunication industry and suggest some strategic and practical implications.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.158-166
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• 2002

In this paper, we introduce the software and hardware of the measurement system for on-line testing and evaluation of high speed railway. The test items focus on the verification of the performance and acquirement of the technical data of the high speed railway system. The software controls the hardware of the measurement system, perform the analysis and calculation of measurement data and acts as interface between users and the system hardware. For this purpose, three programs a measuring program, a monitoring program and post-processing program are developed. The detailed test scenario is in the process of development to closely follow the process of development and design of the system.