• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1650-1655
• /
• 2010

This paper presents an activation plan for reliability centered maintenance (RCM) of rolling stock. The KTX is carrying out the maintenance in compliance with RCM. MKBSF, that is one of the reliability indices for KTX, is shown 183,483 km in 2009, whereas it is shown 68,986 km in 2004. It means that the reliability of KTX has been growing every year. It also is result of reliability management activities. KORAIL did not apply RCM until now about the conventional rolling stocks. But KORAIL decided that applies RCM system because of reliability management effect of KTX. In this study, we tried to know an activation plan for the reliability centered maintenance of the conventional rolling stocks.

• Journal of the Korean Society for Railway
• /
• v.15 no.5
• /
• pp.508-516
• /
• 2012

The lifespan of a rolling stock is limited to 25 years by the urban railway law. But it can be extended to 40 years by conducting the regular safety test. This gives additional 15 years of lifespan. In Seoul Metro, Many of the rolling stocks were already replaced with new types in 1996 and 2008. New type - VVVF rolling stocks have better safety, maintainability, durability than old types. For this reason, it is desirable to extend the lifespan of new type-rolling stocks. In this paper, we investigated the economical lifespan using LCC (Life Cycle Cost) analysis. This study shows that the economical lifespan comes out 41 years when extra 10% cost has been considered after 25 years of the train service and 46 years when extra 10% cost not considered.

• Journal of Welding and Joining
• /
• v.21 no.1
• /
• pp.42-47
• /
• 2003

Stainless rolling stocks are usually fabricated by spot welding process without painting. Indentation on the surface of the car body after spot welding injures the beauty of the stainless rolling stocks. In this study, insulated electrode tips to reduce the indentation are developed and applied to the actual spot welding works. The developed tips are composed of head, neck, hole for cooling water, body and resistance material. They provide large surface contact area with the base materials during spot welding and enhance the current density by necking. Experimental results using the developed tips show that small indentation and sufficient tensile shear strength is produced due to large contact area and enhanced current density.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1178-1185
• /
• 2010

Recently, high speed of container freight cars is causing fatigue damage of wheel. Sudden failure accidents cause a lot of physical and human damages. Therefore, damage analysis for wheel prevents failure accident of container freight car. Wheel receives mechanical and thermal loads at the same time while rolling stocks are run. The mechanical loads applied to wheel are classified by the horizontal load from contact of wheel and rail in curve line section and by the vertical force from rolling stocks weight. Also, braking and deceleration of rolling stocks cause repeated thermal load by wheel tread braking. Specially, braking of rolling stocks is frictional braking method that brake shoe is contacted in wheel tread by high breaking pressure. Frictional heat energy occurs on the contact surface between wheel tread and brake shoe. This braking converts kinetic energy of rolling stocks into heat energy by friction. This raises temperature rapidly and generates thermal loads in wheel and brake shoe. There mechanical and thermal loads generate crack and residual stress in wheel. Wetenkamp estimated temperature distribution of brake shoe experimentally. Donzella proposed fatigue life using thermal stress and residual stress. However, the load applied to wheel in aforementioned most researches considered thermal load and mechanical vertical load. Exact horizontal load is not considered as the load applied to wheel. Therefore, above-mentioned loading methods could not be applied to estimate actual stress applied to wheel. Therefore, this study proposed safety estimation on wheel of freight car using heat-structural coupled analysis on the basis of loading condition and stress intensity factor.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.7 no.4
• /
• pp.41-47
• /
• 2012

Railroad rolling stock has long service life and a lot of maintenance cost running on rail by wear and vibration. And it is very important to get optimization of maintenance. This paper want to analyze rolling stock maintenance situation of KORAIL and find out its improvement methods. Especially, the purpose of this paper is to adopt the most effective maintenance period and methods to daily inspection which needs many maintenance manpower in rolling stock. Rolling stock has self-diagnosis function using computer system and the quality of rolling stock has much improved these days but current daily inspection repeat for short period routinely and it is very ineffective. Therefore, the paper adopt improved daily inspection period reflecting the characteristics of rolling stock, and want to secure reliability of rolling stock and minimize maintenance cost.

• Journal of the Korean Society for Railway
• /
• v.14 no.3
• /
• pp.211-215
• /
• 2011

Generally, sound power is one of the most significant factors to predict and assess noise from sound sources. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we propose a method to estimate sound power generated due to wheel/rail interaction and propulsive equipment from the measurement of noise emitted from rolling stocks and verify the estimation method by comparing with the other sound power estimation formula. We also analyze the sound power of rolling stocks which are operating in domestic lines such as EMU, Mukoonghwa, KTX using the method proposed in this paper.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.580-584
• /
• 2011

Sound power is one of the most significant factors to predict and assess noise from sound source. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we proposes a method to estimate separately each sound power for rolling noise and propulsive noise with the noise emitted from rolling stocks and verifies the validity of the estimation method using other sound power estimation formula.

• Proceedings of the KSR Conference
• /
• 2003.05a
• /
• pp.656-662
• /
• 2003

The rolling-stocks used in conventional line have suffered wheel problems due to lack of adaptability with track. These brought out severe wheel wear and inefficiency of wheel maintenance. Especially, tight wheel maintenance criteria have caused waste factors of wheel machining, these increases rolling-stock maintenance costs. Thus, this study was started to Propose the wheel maintenance plans to improve maintenance efficiency in respect to wheel maintenance process in rolling-stock workshop. Here, we describe some results

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.119-122
• /
• 2004

Since a derailment of rolling stocks results in huge losses in properties and lives, the measurement of a derailment coefficient is a very important test item to estimate the running safety of rolling stocks. For a measurement of the derailment measurement of forces between the wheel and rail a measuring wheel-set should be made first. The process to make a measuring wheel-set has some stages for correct measurement. They are as follows; a finite element analysis of a wheel to find a position of holes at which vertical force shall be measured, a finite element analysis for the position of strain gauges.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.10
• /
• pp.1005-1013
• /
• 2009

In this paper, the performance improvement of a decentralized brake system for railway rolling stocks is investigated. In order to verify the effectiveness of the decentralized brake system, it is compared to the truck unit brake system which has only one control unit per a truck. The adaptive sliding mode control scheme is used to realize a robust anti-slip brake control system. Through computer simulations, it is verified that the decentralized brake system has better braking performance than the truck unit brake system.