• 한국철도학회논문집
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• 제4권3호
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• pp.116-122
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• 2001

As freight traffic becomes heavier, the high speed of existing freight cars is essential, instead of the construction of a new railway. The high speed can be achieved by the modifications of freight bogie design. In this paper, an analytical model of freight bogie is developed to decide the critical speed. The dynamic responses of the analytical model are compared with the experimental data from a running test of freight bogie and showed good agreements between them. The analytical model is used to find the design of freight bogie. The parameter studies show that the reduction of wheelset mass ratio and the increase of the axle distance of freight bogie can increase the critical speed, but the primary lateral stiffness has little effects on the critical speed. And this study also shows that smaller wheel conicity deteriorates the running safety of freight car, which means that the overhauling of the wheel of freight bogie should be done regularly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.179-186
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• 2001

As the freight traffic becomes heavier, the high speed of existing freight cars is essential instead of the construction of a new railway. The high speed can be achieved by the design modifications of the freight bogie. In this paper, an analytical model of freight bogie including the lateral force between rail and the flange of wheel is developed to decide the critical speed, which activates a hunting motion and tells the running safety of freight bogie. The dynamic responses of the analytical model were compared with an experimental data from a running test of a freight bogie and showed good agreements between them. The analytical model is used to find the design modifications of the freight bogie by parameter studies. The results show that the reduction of wheelset mass ratio and the increase of the axle distance of the freight bogie can increase the critical speed, but the primary lateral stiffness has little effects on the critical speed. And this also study shows that smaller wheel conicity deteriorates the running safety of the freight car, which means the overhauling of the wheel of freight bogie should be done regularly.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.16-19
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• 2005

There are about 13,000 freight cars in Korea. The holding amount of the freight cars are many more than the other types of cars. But the bogie structure has many friction parts, so three are many hold-ups for the maintenance problem on the spot. As seen in Fig. 1 friction parts are organized of 30 parts in case of welding structure bogie. Especially left-right positions of the axle box have severe problems for the wear, they occurs the reduction of maintenance period, a lowering of the running safety. Generally the thickness of wear plate is 4.5mm and attached to bogie by way of welding method. At the running situation the friction occurs in wear plate each other. Namely the role of the wear plate reduce the load from the carbody. So we need the wear plate fur low-wearing, adequate friction power.

• Tribology and Lubricants
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• 제22권2호
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• pp.87-92
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• 2006

In tread brake of freight cars, brake force is produced by the friction between the wheel and the brake shoe. Friction coefficients associated with the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and loaded, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake friction materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake friction materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of brake time and temperature. This study presented an experimental evaluation method to secure optimum brake performance by keeping safe brake effect and brake distance by the friction coefficient of the brake shoe of the freight cars.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.62-73
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• 2001

The scope of this study is focused on the survey of new logistics transportation systems in railroad and case studies of new systems such as piggyback system, bi-modal system swapbody, and double stack train(DST). Piggyback system, bi-modal system, swapbody, and double stack train are reviewed in term of technological validity and economic validity in Korea. Piggyback - trailer does pass loaded weight limits but does not pass train limits and can not utilize the existing freight cars. Piggyback - cargo trunk does pass all the criteria and could be developed by a domestic technology. But this study suggests to expand the length of train cars to 18.300mm for accommodation of two cargo trucks. Bi-modal system and swapbody do also pass. Double stack train could only pass the loaded weights and does not meet the train limit and the possibility of using existing freight cars. Domestic technology could not development DST, due to civil engineering construction limits and low standard height of electric line, which could not afford to operate DST.

• 한국소음진동공학회논문집
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• 제20권4호
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• pp.373-380
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• 2010

An interest is increased of environment and energy so, importance on railroad high energy efficiency is magnified. And after Gyeong-bu High speed rail is completed, share rate freight transportation of railroad is expected to be gradually increased due to expand investment for railroad and operate mainly freight transportation on convention line. Therefore a research on DMT freight cars is necessary under like this situation. In paper, we developed analysis model for DMT freight car and DMT freight was analyzed numerically using VI-Rail in each condition of railway having different curve and carried out vibration analysis on curving using developed analysis model. And we carried out test on driving stability follow changing curve radius then measure against UIC code 518.

• 한국철도학회논문집
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• 제15권3호
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• pp.272-277
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• 2012

우리나라 철도운영회사인 한국철도공사의 물류부문 영업계수는 2010년 190.7로서 2009년의 197.4에 비해서 소폭 개선되기는 하였으나 여전히 수익에 비해서 비용이 매우 높은 구조이다. 물류 효율화를 위한 활동들을 도출하고 그 효과를 정량적으로 파악할 수 있기 위해서는 각종 통계자료로부터 추출할 수 있는 다양한 지표의 분석이 매우 중요하다. 철도물류에 있어 가장 기본이 되는 것은 화차이며, 본 연구에서는 화차의 효율성을 판단할 수 있는 여러 가지 지표를 분석함으로써 향후 화차와 관련된 철도물류의 효율화를 위한 활동들을 평가하는 데에 활용할 수 있도록 하였다. 화차의 효율성을 파악할 수 있는 지표로서 량당 수송횟수, 량당 수송거리, 량당 수송수입을 제시하였으며, 화차의 효율성을 평가할 때 본 연구에서 제시한 각 지표의 특성 분석자료를 활용할 수 있을 것이다.

• 한국소음진동공학회논문집
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• 제21권7호
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• pp.637-642
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• 2011

The DMT freight is judged that economic performance is good because can increase cargoes than existing freight. However, the existing freight cars, each with a different balance to the body structure is bogie because the vibrations may occur. Thus, by minimizing vibration over the existing freight securing the safety of the driving if you will not have major problems in cargoes. In this study, multi-body dynamic analysis tool, VI-Rail using the actually Gyeongbu Railroad line and an empty, full freight condition include curve radius, track irregularity, The DMT freight of the derailed wagons were assessed for safety analysis. Full and empty freight conditions for parity in the Gyeongbu Railroad line(Dongdaegoo${\leftrightarrow}$Kyungsan) derailment safety analysis, such as derailment coefficient and the wheel unloaded, echoing the curve and the orbit is affected by the irregularity was found. Full freight condition than the empty conditions showed a significant derailment safety. Overall, the limits of derailment coefficient(Q/P = 0.8) and wheel unload decrement limits(${\triangle}P/P$ = 0.6) is less safe with me confirmed that the derailment safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.830-835
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• 2011

DMT Freight is judged that economic performance is good because can increase cargoes than existing freight. However, the existing freight cars, each with a different balance to the body structure is bogie because the vibrations may occur. Thus, by minimizing vibration over the existing freight securing the safety of the driving if you will not have major problems in cargoes. In this study, multi-body dynamic analysis tool, VI-Rail using the actually Gyeongbu Railroad line and an empty, full freight condition include curve radius, track irregularity, cent. DMT freight of the derailed wagons were assessed for safety analysis. Full and empty freight conditions for parity in the Gyeongbu Railroad line(Dongdaegoo ${\leftrightarrow}$Gyungsan) derailment safety analysis, such as derailment safety coefficient and the radius wheel road decrement, echoing the curve and the orbit is affected by the irregularity was found. Full freight condition than the empty conditions showed a significant derailment safety. Overall, the limits of derailment coefficient (Q/P=0.8) and wheel road decrement limits (${\Delta}P/P=0.6$) is less safe with me confirmed that the derailment safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3299-3305
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• 2011

Railroad is considered a representative echo-friendly mode, but there are many civil complaints due to dusts arising in the process of bulk cargo transportation. The freight station which is handling coal are slowly decreasing because of civil complaints. Generally gondolas and hopper cars kinds of freight cars have a role to carry coal such as anthracite and bituminous coal. The railroad competitiveness in the field of bulk cargo transportation is diminishing because there are cost increase and dust emission in the process of transshipment. In this study, we analysed the logistics process of bulk cargo transportation in the point of railroad and we could draw the problems from the logistics process. The results could be used to study various alternatives to improve the process of coal transportation.