• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.32-36
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• 2002

High-speed movement and high-precision machining are the two most important requirements of present machine tool structures to reduce machining time and to increase the precision of products in various industrial fields such as semiconductor, automobile, and mold fabrication. The high speed operation of machine tools tue usually restricted not only by the low stiffness but also by the low damping of machine tool structures, which induces vibration during high speed machining. If the damping of machine tool structures is low, self induced or regenerative vibrations are bound to occur at high speed operation because the natural frequencies of machine tool structures can not be increased indefinitely. Therefore, the high damping capacity of a machine tool structure is an important factor for high speed machine tool structures. Polymer concrete has high potential for machine tool bed due to its good damping characteristics. In this study, a polymer concrete bed combined with welded steel structure i.e., a hybrid structure was desisted and manufactured for a high-speed gantry-type milling machine through static and dynamic analyses using finite element method. Then the dynamic characteristics were tested experimentally.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3133-3141
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• 2011

The next generation domestic high speed railway system is a power distributed type and uses vector control method for motor speed control. Nowadays, inverter driven induction motor system is widely used. However, recently PMSM drives are deeply considered as a alternative candidate instead of an induction motor drive system due to their advantages in efficiency, noise reduction and maintenance. The next-generation high speed train is composed of 2 converter units, 4 inverter units, and 4 Traction Motor units. Each motor is connected to the inverter directly. In this paper, the effect of IPMSM parameter variations to the system operation characteristics of the multi inverter drive high speed train system are investigated. The parallel connected inverter input-output characteristics are analyzed to the parameter mismatches of IPMSM using the 1C1M control simulator based on Matlab/Simulink.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.134-138
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• 1999

For the stable operation of high speed aerostatic spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are not appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, the composite spindles with aerostatic bearing were designed and manufactured with carbon fiber/epoxy composite. The fundamental natural frequency of the composite spindle was evaluated through the modal testing.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.20-27
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• 2011

High-speed railway system is exposed to severe aerodynamic problems and has various requirements both on design and operation; 80% of running resistance is composed of aerodynamic drag, the cross-sectional area and portal shape of tunnel should be designed under aerodynamic consideration, and natural wind velocity should always be monitored to prevent the overturning of train by crosswinds. In addition, most of the aerodynamic problems are proportional to the running speed or square of the running speed. Thus, when the running speed of a high-speed railway system either on operation or under construction is to be increased, the aerodynamic problems should be assessed in advance and the countermeasures should be prepared to alleviate the aerodynamic problems to meet certain requirements. In this study, aerodynamic problems that could occur at speed up of high-speed line have been investigated and aerodynamic requirements to meet the increased operational speed have been studied referring the international and domestic rules, guidance, and recommendations.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.370-376
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• 1993

In this paper, we present the voltage source algorithm for high speed and low torque ripple operation of a switched reluctance motor (SRM). The SRM has simpler structure than the traditional dc or ac motor. It has a high starting torque and can be operated in the wide range of speed. So it can be applied to various areas. But the SRM has some difficulties in driving circuit and controller due to the large inductance variations. In this study, in order to produce the low torque ripple and the high speed operation, a voltage source algorithm is proposed. We showed the good performance of the proposed controller through simulation and experiment.

• Journal of Magnetics
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• v.22 no.1
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• pp.23-28
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• 2017

This paper is a study of the eddy current brake designed to replace the air brake of railway application. The eddy current brake has the advantage of being able to take a high current density compared to the other application because this brake is used for applying brakes to the rolling stock for a shorter amount of time. Also, this braking system has the merit of being able to take a high current density at low speed rather than at high speed, because the heat generated by the low speed operation is less than that of the high speed operation. This paper also presents a method of improving the output torque of the eddy current brake at low speed operation through a change of the winding as well as the basic design.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.105-108
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• 1999

In this paper, we define the high-speed router as a router, which can support aggregated ports over 25Gbps, and provide issues and trends in high-speed router design. We propose design considerations on IP packet forwarding, switching fabric, packet scheduling and buffer management, network resource reservation, and router operation and administration.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.298-302
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• 2016

Currently, logistics are in small quantities and in diverse forms, and the amounts are continuously increasing. Railway logistics however are losing their market share every year mainly due to low operation speed and loading time, which means the trucks are covering the most of the freights. In order to solve these situations, this paper proposed the high speed freight train as working multi-modality with other modes to make effective transshipment. The high speed freight train has maximum operation speed of 300km/h and electric power to run centralized power supply. There are large dual door system, bogie system covering fluctuating load of 15[ton], automatic loading device, ULD(unit load device) bed and ULD locking system in this freight rolling stock. We calculated the performance of powering and braking capacity for this train and proposed how many vehicles are composed of train set. The results in this paper can help to make a decision to define the technical specification of High-speed freight train for the efficiency of rail freight service.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.332-338
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• 2022

The article presents a concept of designing a Multiplexer circuit which acts as a "Selector" and that becomes capable to select different speed created at different TTL Gate configurations; Standard TTL(Normal Speed), High Speed TTL(High Speed), Schottky TTL(Super High Speed) and further connect the selected Gate speed to the CAR shape created using C-Programming at Computer Graphics and finally CAR shape display at different speed to the color TV. The Multiplexer supporting efficient and more reliable selection criteria using "Logical based selection criteria" and further the output from multiplexer is provided to CAR shape created using c-programming and finally CAR shape is display to color TV system. Basic purposes and assumptions regarding the design and development of this system as well as a description of its operation have been presented.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1026-1032
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• 2010

In this paper, To estimate the train exterior noise and environment noise which are occur when High-Speed EMU is driving with the speed of 370km/h, Estimated sound source about noise that is appeared during operation based upon noise SPL values. Based on aero-dynamic noise source and wheel-rail noise source, these were already used to the existed research, we have estimated each sound power about measured noise, and computed the sound source to apply on the High-Speed EMU, and also calculated the sound power in case of the maximum operation speed of 370km/h.