• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2135-2146
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• 2011

The rail surface irregularity is generated severely by train braking effect in the section of station. The braking force increases slip rate and friction factors caused by wheel-rail contact points. It brings rail surface irregularity as well. In this study, interactions between wheel and rail were investigated using rolling contact fatigue theory and mechanism of rail degradation through fracture mechanics. For the more, the Von-Mises stress occurred on the rail due to the interaction between wheel and rail was analyzed using 3-D finite element method. The amounts of surface irregularity of rail were measured according to accumulated passing tonnage in urban railway in fields. Therefore, the maintenance of rail should be separated by running and braking sections to prevent RCF defects.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.792-797
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• 2007

This study investigates the change of the temperature and fatigue property of the braking disk (GC25-30 material) for the railway vehicle. The average temperature is measured about $100^{\circ}C$ and the maximum temperature is measured over $200^{\circ}C$ by non-contact sensor from Seoul to Chun-an. In the $20^{\circ}C-300^{\circ}C$. The Fatigue tests did for new and used disk specimens. The fatigue test results of new disk specimens were similar due to the temperature change. But the compare of specimens between new disk and old disk, The fatigue life of old disk specimens was smaller than new disk specimens about 10%.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.566-573
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• 1999

This paper is the result of sensitivity analysis of derailment with respect to the selected suspension elements for the rail vehicle. Derailment phenominon has been explained by the derailment quotient. Thus, the sensitivity of derailment is suggested by a response surface model(RSM) which is a functional relationship between derailment quotient and characteristics of suspension elements. To summarize generation of RSM, we can introduce the procedure of sensitivity analysis as follows. First, to form a RSM, a experiment is performed by a dynamic analysis code, VAMPIRE according to a kind of the design of experiments(DOE). Second, RSM is constructed to a 1$\^$st/ order polynomial and then main effect fators are screened through the stepwise regression. Finally, we can see the sensitivity level through the RSM which only consists of the main effect factors and is expressed by the liner, interaction and quadratic effect terms.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.830-839
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• 2008

This study is designed to manufacture the upgraded sound absorption concrete by using foamed concrete by using artificial light weight aggregate which raises the continuous void ratio to increase the sound absorption ratio and improve the strength. In manufacturing the sound absorption block, the pre-foaming form is applied to generate continuous voids, controlling the density by the addition of bubbles. It is general that the more porosity creates, the weaker strength becomes. Each of specimens are used for this experiment and measured their absorption ratio to examine the absorption property depending on frequency. As a results of experiment, it is evaluated that the absorption capacity of the sound absorption block has relation to compression strength and surface shape.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.596-601
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• 2008

Larger amount of composite materials are used for light train. These days even the body structure of the coach was made by composite materials. In this study, we made the fire simulation with FDS by HRRPUA method for the passenger coach of carbon-epoxy composite material body structure. For the body structure fire resistance verification, 1.8 liters of gasoline were selected for fire source. For the interior fire case, 4.0 liters of gasoline fire source was selected as Daegu fire accident case.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.455.1-455.1
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• 2014

폴리머 애자는 기존 사기 재질 애자에 제조비용과 설치비용이 저렴하며 훌륭한 내구성과 경량화에 따른 취급의 편의성으로 최근 기존 애자를 대체하기 위한 연구와 실증이 활발하다. 그러나 폴리머 애자는 재질의 한계로 인해 유증에 따른 오염에 취약한 단점을 가져 터널내부와 전기철도차량에 사용하는 것에 있어 한계를 가진다. 폴리머 애자의 활용성을 높이기 위해 본 연구에서는 폴리머 애자의 표면을 플라즈마 처리를 하여 표면개선을 하는 연구를 진행하였다. 반응가스로는 산소, 질소, 수소, 아르곤 등의 가스를 사용하였고, 플라즈마 소스는 마이크로웨이브 플라즈마와 DC 플라즈마를 사용하였다.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.71-77
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• 2013

This study analyzes how deep acting and surface acting, both classified as emotional labor, influence emotional exhaustion and turnover-intention for 263 KTX attendants. The followings are the summarized results of our analysis. First, the deep acting of KTX attendants does not affect emotional exhaustion, but surface acting was found to have a positive influence on emotional exhaustion. Second, the deep acting of KTX attendants had a positive impact on turnover-intention, but surface acting did not affect turnover-intention. Last, the emotional exhaustion of KTX attendants had a positive impact on turnover-intention. In conclusion, these results imply that it is important for employers to manage their employees' emotion in order to prevent turnover among KTX attendants.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.77-86
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• 2005

Since slope sliding and loss of railway triggered by a rainfall produce instability in the operation of trains, a proper method to estimate the slope stability considering rainfall Is required. from the field study, sliding induced by rainfall depends on the engineering properties of soils, three dimensional aspect of the slope, rainfall intensity and geological conditions of the soil layers. In this study, among various types of sliding, slope Instability caused by the surface runoff water at the concave zones in a slope is investigated. The depth of runoff water is calculated by using the Rational method and Manning equation. The occurrence of runoff water is evaluated by a comparison between the calculated infiltration rate and rainfall intensity. Pressure heads which can be calculated from the modified Iverson model are used to calculate the factor of safety along the vertical depth of the slope. The modified Iverson model considers the depth of runoff water, thus the maximum hydraulic gradient along the depth of slope is greater than one.

• Fire Science and Engineering
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• v.23 no.6
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• pp.57-65
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• 2009

Fire suppression tests are carried out for a train car using water mist systems. Three kinds of fire scenario applied to the real-scale train car are a surface fire representing car combustibles, a oil pool fire pretending an oil spill and a blocked fire for evaluation of space-cooling capacity. Five fixedpressure water mist systems and one self-contained water mist system with nitrogen gas are used for fire suppression experiments. Almost water mist systems can extinguish effectively train car fires, and fire-control capability of the system is seen due to the space cooling.

• Journal of Welding and Joining
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• v.22 no.3
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• pp.32-38
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• 2004

알루미늄은 중량대 강도의 비가 여타의 구조용 재질에 비해 뛰어나고 가공 및 용접성이 양호하기 때문에 수송수단의 경량화를 위해서는 가장 좋은 재질로 인정되고 있다. 또한 표면의 산화막은 내부식성을 향상시키므로 차량의 수명 향상에 기여할 수 있고, 우수한 재활용성은 환경 보전에도 기여할 수 있다.(중략)