• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2987-2997
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• 2011

As a public transit playing an important role in the era of high gas prices, subway corresponds the national strategy 'Low carbon, Green growth'; accordingly, passengers who would use the transportation are steadily increasing. Subway operators are required to provide subway users with services based on higher-quality system, safety, convenience & high reliability level. Furthermore, as the legally allowed maximum life time of EMUs is extended, it is necessary to localize & standardize the parts of EMUs. This paper presents a modelling of systematic EMU(SR001) manufacturing technique which enables us to reflect passenger and subway operator's demands in the whole EMU manufacturing process from the initial design phase to its completion by making full use of the know-how based on subway operators' experiences. SR001 enabled SMRT's staffs to participate in the EMU design & its equipment manufacturing; consequently, it realized the innovative system which meets passengers' requirements. Moreover, the process lead time was reduced dramatically. The result of this research will be helpful in providing useful guidelines for railway industry policy and development making in Korea.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1864-1870
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• 2007

The inspection periods for the metro EMU maintenances vary variously according to the countries and railway operators. And the inspection systems vary according to the safety, economical, technical aspects, and also the social environments like passengers and maintenance qualities, etc. Also, in economic point of view, maintenance requires the man power, facilities, equipments, purchasing of parts and the loss of not being in revenue service during the maintenance period. Recently, there is a tendency that the inspection periods are extended gradually owing to the increased reliabilities of the equipments and parts of EMUs. Even if it is the EMUs that are already be in service, once the inspection method is innovated, the inspection time can be reduced. The inspection management innovation scheme includes such methods as the complete module to module replacement when trouble shooting a faulty parts before putting the EMU back to revenue service, the replacements of parts in complete set unit for the heavy maintenance, the establishments of exchange periods for the wasting parts, modernization of inspection equipments, introduction of RAMS for the reliability improvement and computerization of EMU maintenance management, etc. I think it is possible to optimize the inspection scopes and periods per parts and equipments by the introduction of RAMS.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.356-361
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• 2005

Earth brush for electrical multiple units(EMUs) is a device through which the current of the EMU load's consumed power fed from the DC 1,500V overhead line (or from the AC 25.000V catenary) flows via axle to the rail(ground) and which prevents the electric corrosion of the axle bearings by preventing the current flow to the axle bearings caused by electric potential from the magnetic field when the bearings rotate together with the earthing function when a thunderbolt falls or a surge comes. The earth brush wear rates among cars, however, shows quite differences when the earth brushes after being separated from the holders are measured with vernier callipers every 6 months of maintenance period. Main causes of the earth brush wear are divided as mechanical, electric arc and electrical one, and the factors can be running speed, current, harmonics, connection state. spring tension, earth brush material, lubricant and so on. but only the earth brushes of the motor(M1) car show the highest wear rate and moreover maintenance difficulty occurs because of the wear rate differences among e earth brushes in one holder. The reason for these preponderant wear comes from the design concept of making preponderant current flow to some particular earth brushes and moreover the heat generated by the harmonics when the inverter starts to operate accelerate the wear. By defining these causes through experiments. I hope that the found results would be helpful for the future EMU design, safety, economy and maintenance.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.117-122
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• 2017

In this study, we studied the ride quality considering the deterioration effects of the three type couplers (single, double, and ring types) for EMUs. In order to know the impact occurred when an urban transit vehicle is under breaking, we tested the conditions of the service brake and the emergency brake. Normal coupler models without any slack showed similar dynamic performance results under all breaking conditions. But if the couplers become old, the initial pre-stresses are removed because of permanent compressive deformation in rubber. For three types of the old coupler models without the initial pre-stress, we evaluated dynamic performances of each type. As the results, the maximum and average acceleration levels of the double type and the ring type were similarly low in all conditions. But the accelerations of the single type coupler was high when compared to those of the double and ring types. In addition, Jerk value of the single type model associated with ride quality was high up to 15 times to the ring type in condition of the service braking in empty vehicle weight. Jerk value of the double type model was high up to 6 times to the ring type.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.211-215
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• 2008

Generally, an EMU (Electronic Multiple Unit) is manufactured by assembling a large number of components and parts with extensive raw materials. Throughout its entire life cycle, much both the complicated system and long operating period. Therefore, it is necessary to the environmental performance of EMUs from raw materials to waste. In this study, RACE (Rail Assessment for Clean Environment) was developed as the software that can analyze the environmental RACE had several LCI (Life Cycle Inventory) database for main components as well as principal materials in EMUs. In the future, RACE can also be used as a tool for environmental communication between manufacturers and operators. Also, we will improve RACE continuously to assess more easily the environment of rolling stocks EMU for user.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.447-452
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• 2005

Nowadays domestic demands for urban EMUs are gradually increased due to traffic jams and environmental problems. Therefore it has been required to make sure of manufacturing quality and to acquire cost effective bogie frames through mass production. One of the major functions of bogie frames is to guarantee the static strength and durability. In this research, the comparison between FE analysis and actual load test results is performed for the bogie frame, which is manufactured by Rotem Company. The results show that the standardized bogie frame meets the strength requirements of domestic regulations.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.646-658
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• 2006

In this paper, the details of electric traction voltages which are widely used for metro and mainline trains are presented. The problems encountered in catenaries, pressure of the pantograph pan, catenary contact cross sectional area, materials etc are well covered. Catenary height from the rail for main line, bridges, sheds etc is discussed. The catenary running details and switching of one catenary to another are explained. The dead zones in 3 phase grid as well as in DC are presented here. The pantograph structure, blades, shoes etc. for AC/DC EMUs are dealt. The schematic diagram for electrification systems used for railways are given and explained with typical electrical parameters of Indian Railways.

• Journal of Power Electronics
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• v.14 no.3
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• pp.572-579
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• 2014

As a non-linear time variant system, the four-quadrant line converter of an electric multiple unit (EMU) was expressed by linear time periodic functions near an operating point and modeled by a steady-state harmonic domain matrix. The components were then combined according to the circuit connection and relations of the feedback control loops to form a complete converter model. The proposed modeling method allows the study of the amplitude of harmonic impedances to explore harmonic coupling. Moreover, the proposed method helps provide a better design for the converter controllers, as well as solves the problem in coordination operation between the EMUs and the AC supply. On-site data from an actual $CRH_2$ high-speed train were used to validate the modeling principles presented in the paper.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.10
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• pp.1406-1410
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• 2003

The studies were based on the RAPD fingerprinting for the species identification of animals. The genomic DNA samples of ostriches, Taiwan local chickens, Aboracres broilers, Leghorn chickens, quails, doves, emus, Beltville small white turkeys, pheasants, Chinese geese, mule ducks, Holstein cattle and Landrace pigs were amplified with random primers by RAPD-PCR for fingerprinting. The results showed that the varied band patterns of DNA fingerprints were generated from templates depending on the kinds of primers or animal species. The same primer applied to the same breed, all of the main bands are similar, but which were different among species. In order to try to identify the species from the mixture of meat by RAPD fingerprinting, the meat of ostrich and cattle was mixed in different ratios for this study. The results showed that it could be easily and precisely distinguished according to the band distribution of RAPD patterns.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1458-1465
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• 2008

With 34 years of accumulated operating experience, Seoul Metro has launched a project aimed at exporting second-hand trains(used EMU cars) to Vietnam while seeking measures for diversifying its business such as the construction of the metropolitan railways both at home and abroad, and operating business as a way of fiscal consolidation and management improvement. Therefore, Seoul Metro has moved ahead with this plan considering that there's no legal constraints on durable period of rolling stocks in advanced countries where the vehicles have been used for 35 years or longer than 40 years through renovation such as safety inspection and comprehensive maintenance program, and the railway systems for the replacement are expected to reach 838 cars by 2015 with growth of 100 cars a year. Seoul Metro strives to create value for boosting revenues and recycling resources by sending used EMUs to Vietnam. Seoul Metro will also provide under-developed countries with cars at a low price as well as share the accumulated railway technical know-how so that it can promote the national image and obtain the pre-emptive effect of metro railways in Vietnam.