• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.57-59
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• 2018

This paper presents a novel reference variable speed control scheme of a BLDC motor for the high-speed blender machine according to the current limit. Because of a pulsating load variation of a high-speed blender machine, the actual speed is pulsated by the current limit in the high-speed region. The proposed control scheme uses a variable reference speed to reduce the speed variation from the current limit in the constant power region. The pulsated load is occurred at the material crushing, then the pulsated load is reduced after grinding. The reference speed is smoothly reduced at the pulsated load variation, then the enough torque can make a constant speed during crushing. When the pulsating load is reduced, the reference speed is automatically increased to the original speed value. The proposed control scheme is verified by experimental result by practical blender machine.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.467-472
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• 2005

The characteristics of dynamic vibration are generally analyzed by an acceleration of a car body of high speed train and the acceleration can be applied to evaluation of running safety. The test of process and the analysis method about it are well explained on UIC Code 518 OR which is the spacial international standard about running safety and dynamic behavior on the line test for railway vehicle. Korean High Speed Train designed to operate at speed 350km/h has been tested on high speed line since it was developed in 2002 and it recorded the highest speed 352.4km/h at the 16th Dec. 2004 in Korea. This paper includes the analysis of running behavior of this train at speed 350km/h and also the analysis of dynamic safety is presented in it, extending to the range of high speed while the UIC 518 limit the speed below 200km/h.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1249-1253
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• 2009

Enhancements of transport capacity in Gyeongbu line are continuous with the operating cost reduction and Korean economic development. Besides, requirements of a people about speed-up and customer service after the opening of high-speed railway(KTX) are being increased nowadays. Therefore, development and effort for speed increase of high-speed railway(KTX) have to be encouraged and supported by the government. In this study, market and technology trends for speed increase of high-speed train in Korea and abroad were investigated. As a result, we suggested to improve the railway infra for speed increase of high-speed train in Gyeongbu line.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.203-211
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• 2015

Ride comfort of a vehicle can be utilized to maintain the track geometry and track irregularities because ride comfort of the rolling stock is affected by the characteristics of the vehicle and track. Ride comfort was evaluated according to the measured floor acceleration data of vehicles for a Korean high speed line as well as European high speed lines using Continuous comfort method which can be applied to track maintenance. The exceedance distribution of the ride comfort was quantitatively analyzed by the vehicle speed, the ride comfort of the Korean high speed line was compared with that of European high speed lines. It is shown that the ride comfort of Korean high speed line is better than that of European high speed lines, which indicates that the Korean track geometry and track irregularities are properly maintained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.50-55
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• 2012

The important problem in high speed spindle is to reduce and minimize the thermal effect by motor and bearing. This paper presents the thermal characteristic analysis for a high speed spindle with and without cooling at the rear part, considering the viscosity and the flow rate of cooling oil. A high speed spindle is composed of angular contact ceramic ball bearings, high speed built-in motor, oil jacket cooling and so on. The thermal analyses of high speed spindle need to minimize the thermal effect and maximize the cooling effect and they are carried out under the various cooling conditions. Heat generations of the bearing and the high speed motor are estimated from the theoretical and experimental data. This result can be applied to the design and manufacture of a high speed motor spindle.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.87-94
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• 2003

This paper presents results of the development of the turbo generator system with structure which is HSG(High Speed Generator) installed directly to gas-turbine engine. Turbo generator with a high speed motor-generator directly has many advantages aspects of weight, size, lubrication system and complexity of the system compared of conventional turbo generator system with a gear box. But because of direct high speed operation of the high speed generator, we have to need stable high speed motor driving algorithm for perfect engine ignition when engine start. Also we have to need the design of the Power conditioning unit(PCU) for converting high speed AC output power to conventional AC power or needed DC power.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1767-1776
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• 2001

For the stable operation of high speed air 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 net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.100-105
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• 2003

With the recent development of machining technology, high speed machining process is widely used for-the mold and difficult-to -cut-materials machining since it allows achieving high productivity and surface quality. However, during the high speed machining process, high cutting speed and feed rate can cause abrupt tool life decrease due to rapid rising of the cutting tool temperature. Such situation may cause increase of machining cost. Thus, in this study, developed optimization algorithm is applied to determine optimal machining variables for multiple high speed machining. The R-T characteristic curve for machining economics problems with a linear-lorarithmic tool life model is determined by applying sensitivity analysis. finally, a series of high speed machining experiments are performed to determine the desired optimal machining variables, and the results are analyzed.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.342-345
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• 1997

To achieve adequate brake performance in high-speed trains the brake system should : ${\bullet}$ offer high reliability and high availability, ${\bullet}$ permit deceleration of the train with as little wear as possible, and ${\bullet}$ display good control characteristics with, if possible, infinitely variable control of the braking effort. For these reasons, high-speed train is to be equipped with three different and largely independent brake system : ${\bullet}$ a regenerative brake with regenerative feedback in the driven cars, ${\bullet}$ a linear eddy-current brake in the nondriven cars and ${\bullet}$ a pneumatic disc brake in all cars. This paper describes the conceptual design of braking system for Korea High Speed Train with the maximum speed of 350km/h

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.329-334
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• 2002

High-speed machining is one of the most effective technology 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, spindle revolution and cutting force are control factors. The effect of the control factors on machining accuracy is discussed for the results of surface roughness and machining error in Z-direction for the high speed machining of STD11.