• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1915-1916
• /
• 2006

Recently, for positioning a train and synchronizing between equipments in railway environment, the utilization of GPS(Global Positioning System) is increasing. But, the defects of GPS are pointed out. The risk of dependence on only GPS is not neglectable. Therefore, we prepare the implementation of the future railway system through the research on the safety and reliability of applying GPS to railway system.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1025-1026
• /
• 2008

The level crossing collision accident which comprises more than 90 percent of all level crossing accidents is one of the most serious safety problems. There is a critical need for providing safe strategy and is focusing on the level crossing information rather than measures at a grade crossing. This study is intended to develop technology for accident prevention and damage reduction based on accident cases analysis result and improvement direction to complement shortcomings of safety equipment of conventional level crossing and to establish safety of travelers(train, motor vehicle, person).

• Journal of the Korean Society for Railway
• /
• v.12 no.5
• /
• pp.732-737
• /
• 2009

Wind tunnel testing on the real-scale pantograph for high-speed train has been conducted to investigate the aerodynamic characteristic of the pantograph at high-speed. The mid-scale subsonic wind tunnel of Korea Airforce Acamedy with 3.5m width, 2.45m height, and 8.8m length test section has been employed. The test model has been supported above 50cm height from the bottom of test section using vertical strut to eliminate the boundary layer generated from the bottom of the test section. The height of the pantograph has been varied in three cases, in both of the normal running and reverse running modes. The resultant lift forces of the pantograph to catenary system in all the cases have been measured and the relation between the test conditions and the lift forces have been extensively analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.6604-6610
• /
• 2015

In this paper, an efficient Wireless Access in Vehicular Environment (WAVE) packet transmission scheme for railroad communication is proposed. WAVE communication is a wireless local area network (WLAN) based communication and it is developed to be suitable for vehicular communication. There has been a lot of study on WAVE's applicability to Intelligent Transport System (ITS). As one of main transportation methods, by using WAVE, quality of railroad communication including WLAN based Communication Based Train Control (CBTC) can be enhanced and variety of railroad communication systems can be integrated into WAVE. However, there are technical challenges to adopt WAVE in railroad communications. For the simplest single-PHY WAVE, time division alternation of 50ms between Control Channel (CCH) and Service Channel (SCH) is required. Since there are delay sensitive railroad traffic types, alternation operation of CCH and SCH may cause performance degradation. In this paper, after identifying a couple of problems based on detailed analysis, a novel packet transmission scheme under railroad environment is proposed. In order to verify if the proposed scheme meets the requirement of railroad communication, WAVE transmission is mathematically modeled.

• Journal of the Korean Society for Railway
• /
• v.15 no.2
• /
• pp.135-140
• /
• 2012

Interior Permanent Magnet Synchronous motors (IPMSM) with concentrated winding are superior to distributed winding in the power density point of view. But it causes huge amount of eddy current losses on the permanent magnet. This paper presents the optimal permanent magnet V-shape on the rotor of an interior permanent magnet synchronous motor to reduce the core losses and improve the performance. Each eddy current loss on permanent magnet has been investigated in detail by using FEM (Finite Element Method) instead of equivalent magnetic circuit network method in order to consider saturation and non-linear magnetic property. Simulation-based design of experiment is also applied to avoid large number of analyses according to each design parameter and consider expected interactions among parameters. Consequently, the optimal design to reduce the core loss on the permanent magnet while maintaining or improving motor performance is proposed by an optimization algorithm using regression equation derived and lastly, it is verified by FEM.

• Journal of agricultural medicine and community health
• /
• v.25 no.1
• /
• pp.133-147
• /
• 2000

To provide data for the improvement of primary health care through the study on the utilization rate of community health practitioner(CHP) post and its related factors toward some rural residents in Mooan County Chollanamdo, a questionnaire survey was made from 382 persons during August 1999. Comparison was made between persons at the seaside area under difficult transportation and persons at the railroad area under convenient transportation. The results are as follows: 1. For the last one year, 83.3% of seaside area residents and 67.0% of railroad area residents used CHP post. As the purpose of visit to CHP post at seaside area, 94.3% visited for medical care, 25.3% for chronic disease control and 22.2% for health counselling and 14.1% for chronic disease control. 2. By simple analysis, sex, age, marital status, educational level, residence area, distance from living village to CHP post, presence of chronic diseases, satisfaction with CHP and confidence on CHP were related significantly with the utilization of CHP post for the last one year. 3. By multiple logistic regression, statistically significant variables related with the utilization rate of CHP post for the last one year were analyzed as age, sex, residence area and distance from living village to CHP post.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.578-585
• /
• 2018

This paper proposes a design method for a 3-phase interior permanent magnet synchronous motor (IPMSM) and clamping force control method for an electro-mechanical brake (EMB) using co-simulation for a high-speed train (HST). A traditional pneumatic brake system needs much space for the compressor, brake reservoir, and air pipe. However, an EMB system uses up to 50% less space due to the use of a motor and electric wires for controlling the brake caliper. In addition, it can reduce the latency time for brake control because of the fast response and precise control. A train that has many brakes is advantageous for safety because of the control by sharing the braking force. In this paper, a driving method for a cam-shaft-type EMB is modeled. It is different from the ball-screw-type brakes that are widely used in automobiles. In addition, a co-simulation method is proposed using JMAG and Matlab/Simulink. The IPMSM was designed and analyzed with the JMAG tool, and the control system was simulated using Matlab/Simulink. The effectiveness of the co-simulation results of the mechanical clamping force and braking force was verified by comparison with the clamping force specifications of a HEMU-430X HST.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.1060-1066
• /
• 2008

Bi-modal tram is a new conceptual transit mean for public transportation integrating thoroughfare and railroad vehicle's characteristics together. This paper describes about a software design which will be applied to an automatic driving system, which is called NCS (Navigation Control System), considering such multiplicity of mechanical characteristic. The NCS adopts propulsion, braking, and direction control functions for a tram and utilizes various sensors to fully take control over such functions. In this paper, we defined and analyzed the capabilities of the NCS. Those capabilities are designed with a UML 2.0 based object-oriented modeling technique. Moreover, to ensure the complete operation of such capabilities, a communication protocol (which is capable of controlling sensors, propulsion, brakes, and traveling directions) is designed here. Throughout the paper, firstly, all the NCS related functions are discussed in accordance with the equipments they are belonged to; secondly the UML modeling application techniques for the defined functions and protocols for the communications between equipments are introduced; and lastly a validation process for the design specifications is going to be discussed.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.264-268
• /
• 2005

Most of the train brakes depends on friction between wheels and tracks. This requires braking force reduced in order not to cause wheel slides since the friction decreases as the train speed increases and consequently results in extension of braking distance. The braking system called 'Linear eddy current brake' or simply' Eddy current brake' is a braking system for making a brake independent from friction, which consists in creating electromagnet by coiling around shoes attached. to bogies; having the shoes above the tracks approached to the tracks upon acknowledgement of a braking command; and authorizing braking force that is irrelevant to friction through magnetic repulsion between electromagnet attached to the tracks and train set by the use of the electromagnet's magnet field characteristics. An electromagnetic attraction braking system that consists in pressing pole shoes attached to bogies against the tracks by using electromagnet's attraction force is called 'Electromagnetic track brake' or simply 'Track brake'. This paper has been prepared in purpose of studying technological tendencies of the eddy current brake and the track brake so that it can be utilized as fundamental data for commissioning Korean high-speed trains with the eddy current brake hereafter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.5
• /
• pp.53-60
• /
• 2002

This paper presents exact autotransformer-fed AC electric railroad system modeling using constant current mode, and single-phase STATCOM(Static Synchronous Compensator) which has an effect on electric railroad system. An AC electric railroad is rapidly changing single-phase feeding electric power. To avoid voltage fluctuation under single phase loads, electric power should be received from a large source. The system modeling theory is based on the solution of algebraic. The AC electric railroad load model is nonlinear. Therefore this paper is considered nonlinear load using PSCAD/EMTDC. And the proposed modeling method is considered the line self-impedances and mutual-impedances that techniques for the AC electric railroad system modeling analysis, and that single-phase STATCOM can reliably compensate the voltage drop. In the case study, the allowance range of feeding voltage is 22.5∼27.5 kV, AT-fed AC electric railroad system circuit is analyzed by loop equation both normal and extension modes. The simulation objectives are to calculate the catenary and rail voltages with respect to ground, as the train moves along a section of line between two adjacent ATs. The results show that single-phase STATCOM can reduce the voltage drop in the feeding circuit and improve the power quality at AC electric railroad system by compensating the reactive power.