• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.461-466
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• 2006

In order to transport cargo rapidly and safely from the trans-Korean railway to the trans-Siberian railway having a different gauge, a gauge-changeable freight wagon can be used. Because the wagon is expected to run in South Korea, North Korea and Russia, it should have good dynamic performance in these railways. In this paper, the dynamic characteristics of a gauge-changeable freight wagon was analyzed numerically using ADAMS/Rail in each condition of the railways having different gauges and rail profiles. The wagon makes use of load sensitive friction damping and has highly nonlinear behaviour, which is modeled in detail as the full nonlinear dynamic model. It is shown that the running behaviour of the wagon is sensitive to changes in the rail gauge and profiles, however the assessment quantities from the point of view of safety, track fatigue and running behaviour are less than the limit valves.

• Wind and Structures
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• v.6 no.5
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• pp.325-346
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• 2003

High-sided road vehicles are susceptible to a sharp-edged crosswind gust, which may cause vehicle accidents such as overturning, excessive sideslip, or exaggerated rotation. This paper thus investigates the dynamic behaviour and possible accidents of high-sided road vehicles entering a sharp-edged crosswind gust with road surface roughness and vehicle suspension included. The high-sided road vehicle is modelled as a combination of several rigid bodies connected by a series of springs and dampers in both vertical and lateral directions. The random roughness of road surface is generated from power spectral density functions for various road conditions. The empirical formulae derived from wind tunnel test results are employed to determine aerodynamic forces and moments acting on the vehicle. After the governing equations of motion are established, an extensive computation work is performed to examine the effects of road surface roughness and vehicle suspension on the dynamic behaviour and vehicle accidents. It is demonstrated that for the high-sided road vehicle and wind forces specified in the computation, the accident vehicle speed of the road vehicle running on the road of average condition is relatively smaller than that running on the road of very good condition for a given crosswind gust. The vehicle suspension system should be taken into consideration, and the accident vehicle speed becomes smaller if the vehicle suspension system has softer springs and lighter dampers.

• Tribology and Lubricants
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• v.24 no.6
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• pp.302-307
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• 2008

The running-in behaviour of the metal carbon coating (WC/C) was evaluated with regard to its applicability as wear-resistant coating for key components in engines. Reciprocating wear tests under lubricated condition employing an oscillating friction wear tester were performed to investigate the tribological behaviors of the coatings in ambient environment. Confocal microscopy and scanning electron microscopy were used to observe worn surfaces and the wear scars on the steel balls. Elemental composition of the coating and worn surfaces were characterized using Auger electron spectroscopy. The friction behavior of WC/C coating was comparable to common carbon-based coatings. Thin tribofilm was formed on the worn surface of the steel ball due to material transfer and tribochemical reaction whereas there was no evidence of tribofilm generation on the coating surface. indicating the chemical innertness of WC/C coating.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.127-131
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• 2005

The running test for the Korean High Speed Train(HSR-350x) was performed at operating maximum sped(350km/h) at December 16th, 2004. HSR-350x had been fabricated in June, 2002 and the on-line test for the performance fo HSR-350x was started with 60km/h at August 19th, 2002. The success of running test at 350km/h is recorded the 4th rank in the world. In this paper, the measured results of the major performance(running behaviour, current collection, stability of rail and bridge) characteristics for HSR-350x are reviewed. All measured values are within the criteria.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1282-1288
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• 2006

Upon demands for the requests of rapid, safe and comfort transit, the proven high speed bogie having not only high-quality but also good running performance is required by customer all over the railway vehicle for narrow gauge. Hereupon, the running test on roller testing rig for developed semi-high speed bogie for narrow gauge was carried out in order to verify the running performance and safety. The aim of the test is to assess the dynamic behaviour of the bogie on straight track including the running stability, ride quality, modal frequency and dynamic response.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1138-1143
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• 2007

Since Maglev vehicle is run over an elevated guideway, the vibrational characteristics of guideway affect the running behavior of the vehicle and guideway. The design of a guideway has a strong effect on the costs of constructing guideways, therefore optimized design of the guideway satisfying running performance is needed for the commercialization of the Maglev vehicle. With an analysis program for dynamics of Maglev vehicles, the dynamic responses of the Maglev vehicle with electromagnet suspension are numerically analyzed according to changes in fundamental natural frequency ratio of a guideway.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1091-1096
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• 2007

Since Maglev vehicle is run over an elevated guideway, the structural properties of guideways affect the running behavior of the vehicle and guideway. The design of a guideway has a strong effect on the costs of constructing guideways, therefore optimized design of the guideway satisfying running performance is needed for the commercialization of the Maglev vehicle. With an analysis program for dynamics of Maglev vehicles, the dynamic responses of the Maglev vehicle with electromagnet suspension are numerically analyzed according to changes in fundamental modal damping ratio of a guideway.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.793-799
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• 2011

A comprehensive analysis of wheel force spectrum is conducted to provide the KTX safety evaluation with structural behaviour of Pre-Stressed Concrete (PSC) box bridge due to various high speeds. The wheel spectrum for KTX locomotive running over road and PSC bridge tracks is compared using irregular track responses with numerical models of 170m approach road track and 40m span length of PSC box bridge The high-speed railway locomotive is used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing) for one car-body and two bogies are considered in the 38-degree of freedom model. Three dimensional frame element of finite element method (FEM) is used to model of the simply supported PSC box bridge. The irregulation of rail-way is derived using the experiential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic analyses by Runge-Kutta method which are able to analyze the high frequency wheel force spectrum. A dynamic behaviour of KTX due to high speeds until 450km/h developing speed with relative time is analysed and compared the characteristics running over the road and PSC box bridge tracks. Finally, the KTX integrated evaluation method of safety between high speed train and bridge is presented.

• Fisheries and Aquatic Sciences
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• v.4 no.3
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• pp.130-137
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• 2001

In the present study, the locomotor and feeding activities of single red sea bream, Pagrus major were simultaneously investigated to examine the existence of such dual behaviour. Seven red sea bream of 13cm body length on average were placed individually in 35L tanks equipped with an infrared sensor and a newly developed demand-feeding device. Fish were exposed to a light: dark 12: 12h cycle and constant darkness (DD) to study endogenous rhythmicity. Under LD 12: 12 h, the daily pattern of behaviour differed between individual fish; some red sea bream were diurnal and others were nocturnal. Futhermore, some of them displayed an extraordinary flexibility in phasing because they were dark active but light feeding, and vice versa. Under DD, red sea bream showed free-running rhythms for locomotor activity and feeding. These results indicate that the type of phasing of locomotor activity did not necessarily decide the feeding phase; much of this is explained by the fact that red sea bream were demand-fed. Flexibility in phasing and a certain degree of independence between locomotor and feeding activities could be seen as an adaptative response of the highly adaptable circadian rhythms of fish.

• Journal of KSNVE
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• v.6 no.4
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• pp.503-511
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• 1996

There is a tendency of using the resilient mounting system to control the structure born noise transimitted from a engine of which weight is comparatively light and of which speed is comparatively high. According to recent reports, the resilient mounting system is applied to control the vibration of a engine running up to 300 - 400 R.P.M.. Furthermore, the resilient system is also used to the ships such as marine exploring ships, fishing boats, and military vessels. It is not desirous to apply the results for the resilient mounting systems of automobile engines to the controls of the vibrations of marine engines. Marine engines are worked under the idle speed in port and are operated up to the maximum contineous revolution at sea(running up condition). And marine engines are usually worked in inevitable conditions such as a misfire and a cut-off cylinder operating condition. Concerning the above running conditions, a resilient mounting system should be designed in the case of marine engines. In this paper, we studied the effect of engine's misfire on the resilient mounting systems. And the influences of design parameters, such as dynamic characteristics and fitting angles of resilient rubber mountings, were also investigated respectively on the single and double resilient mounting systems.