• International Journal of Railway
• /
• v.6 no.2
• /
• pp.64-68
• /
• 2013

In recent years, the speed of a train has been recognized as one of the important factors to determine the competitiveness as a mean of transportation. In line with this, infrastructure improvements and enhancements are being made with increases in the speed of train. Accordingly, there is a need to establish plans for infrastructure improvements through a comprehensive analysis of signals, track/civil engineering, catenary and environment, etc. to improve the speed of a train of high-speed train service sections in Korea. This study proposes improvement plans for catenary systems by investigating the possibility of improvements through performance analysis of catenary equipment by speed increase based on the analysis on catenary systems in Gyeongbu high-speed line, and analysis the applicability of catenary improvements and economic feasibility.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.12
• /
• pp.676-681
• /
• 2002

This paper presents the implementation and experimental investigation of sensorless speed control for a variable-speed PMSM(Permanent Magnet Synchronous Motor) in super-high speed compressor operation. The proposed control scheme consists of two different sensorless algorithms to guarantee the reliable starting operation in low speed region and full torque characteristics using the vector control in high speed region. An automatic switching technique between two control modes is proposed to minimize the speed and torque pulsation during the switching instant of control mode. A testing system of 3.3㎾ PMSM has been built and 90% load test results at 7000r/min are presented to examine the feasibility of proposed sensorless control scheme.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.10a
• /
• pp.50-57
• /
• 1997

A 600HP class high-speed gear driven 3-stage turbo-compressor (IGCC : Integrally Geared Centrifugal Compressor) driven by a 3600 rpm AC induction motor has been designed, of which low speed pinion runs at 35000 rpm and high speed pinion at 50000 rpm nominally. Due to its high speed operation, the system requires very reliable bearing selection and design as well as accurate rotordynamic analysis and prediction of its dynamic behavior to secure the operating reliability. Rotordaynamic analyses of the IGCC rotor-bearing system predicted that the low speed pinion rotor mounted on 5-pad tilting pad bearings has two critical speeds before its design speed and high speed pinion rotor only one critical speed, and estimated critical speeds of both pinion shafts are away from the continuous operating speed enough to satisfy the corresponding API requirement. The forced response analysis with API specified maximum allowable unbalances also showed that unbalance responses are small enough for smooth operation of the system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.131-134
• /
• 1995

The high efficiency and accuracy in machining the die material can be abtained in high speed machining, so it is necessary to analyze the mechanism of high speed cutting process : cutting force, flank wear. The tool dynomometer with high natural frequency is newly developed. With this device, the mechanism of high speed cutting process is investigated according to speed and feedate.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.987-992
• /
• 2000

In a high speed spindle system, it is very important to monitor the operation of the spindle to prevent catastrophic damage to the system. Widely used sensors for monitoring are eddy-current and capacitive types. These sensors provide high accuracy of monitoring, but their steep prices lead to expensive high speed spindle systems. The main goal of our research is to develop technology for producing high speed spindle system utilizing magnetic bearings. As active magnetic bearings require position sensors for feedback control, a noncontact position sensor is being developed as a part of this main goal. Once developed, it will contribute to affordable high speed spindle system. This paper describes the selection process of the sensor types and the design of the driving circuit. We also report the experimental results that characterize the static and dynamic performances of the inductive sensor.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.393-396
• /
• 1997

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 and feed rate are control factors. The effect of the control factors on machining accuracy is investigated using two-way factorial design.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.346-351
• /
• 2001

The technique of high speed machining is widely studied in machining field. Because the high efficiency and accuracy in machining can be obtained in high speed machining. Unfortunately the development of tool for high speed machining is not close behind that of machining tool. So in this study, we made 4 types flat end mill for obtaining data according to tool shape. Especially, we concentrated in helix angle and number of cutting edge. First we confirmed cutting condition by several experiments and measuring cutting force, tool life, tool wear and chip shape according to cutting length. In results, we acquired the fact that 45 degree helix angle and six cutting edge tool is suitable for high speed machining.

• Proceedings of the KSR Conference
• /
• 2001.10a
• /
• pp.358-369
• /
• 2001

KTX will be operated on Kyun-Pu High Speed Railroad Line around end of 2,003 and KHST(G7 Korea High Speed Train) will be carried out the development running test at Kyun-Pu High Speed Railroad Line from middle of 2002. By the way, the conventional Ho-Nam railroad line was passed the limit capacity of transportation at some area from 1997. For solving of this matter, Ho-Nam railroad line need new high speed railroad line for high transportation capacity of passengers now. This report was studied about the rolling stock system design used new technology of KHST and KTX for Ho-Nam High Speed Railroad.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.7
• /
• pp.88-96
• /
• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.926-929
• /
• 2000

Recently, there are lots of applications in machining dies using CAD/CAM systems. which results in reduction of machining time and rising of machining efficiency applying high speed machining and high quality machining. Investigation of machinability is necessary in order to apply high speed machining. In machining complicate 3D model such as connecting rod die. the need of high speed machine and coated tool is requested recently in this field. This paper introduce the database of high speed machining to improve machining efficiency of connecting rod die.