• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4762-4767
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• 2012

The AF track circuit that detecting train position and transmitting various train control data for DTG to the train on-board is composed of single operation system. If a failure occurs on this system, the driver should be operate the train by manually until the system is restored, because the system cannot control switch machines and signals by automatically. In this process the human error affects to the train delay, collision, derailment and critical safety accident. Therefore, this document has analyzed the effects that each failure mode influences on system and train, and quantified the failure valuation point and class. Basis on this quantified analysis result, MTBF increased and MTTR decreased and failure number also decreased by adopting the independent installation of power supply, the replacement of defected capacitors, the installation of resister cooling system and the improvement of maintenance methods. And the failure factors of AF track circuits were decreased by conducting the preventive maintenance which is a quantitative way of maintenance system by experience.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.525-533
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• 2017

Objective: The aim of this study is to investigate maritime officers' strategies to avoid the ship collision in crossing situations. Background: In a situation where there is a risk of collision between two ships, maritime officers can change the direction and speed of the own-ship to avoid the collision. They have four options to select; adjusting the speed only, the direction only, both the speed and direction at the same time and no action. Research questions were whether the strategy they are using differs according to the shipboard experience of maritime officers and the representation method of ARPA (automatic radar plotting aid) - radar graphic information. Method: Participants were 12. Six of them had more than 3 years of onboard experience, while the others were 4th grade students at Korea Maritime and Ocean University. For each participant, 32 ship encounter situations were provided with ARPA-radar information. 16 situations were presented by the north-up display and 16 situations were presented by the track-up display. Participants were asked to decide how to move the own-ship to avoid the ship collision for each case. Results: Most participants attempted to avoid the collision by adjusting the direction of the ship, representing an average of 22.4 times in 32 judgment trials (about 70%). Participants who did not have experience on board were more likely to control speed and direction at the same time than participants with onboard experience. Participants with onboard experience were more likely to control the direction of the ship only. On the other hand, although the same ARPA Information was provided to the participants, the participants in many cases made different judgments depending on the method of information representation; track-up display and north-up display. It was only 25% that the participants made the same judgment under the same collision situations. Participants with onboard experience did make the same judgment more than participants with no onboard experience. Conclusion: In marine collision situations, maritime officers tend to avoid collisions by adjusting only the direction of their ships, and this tendency is more pronounced among maritime officers with onboard experience. The effect of the method of information representation on their judgment was not significant. Application: The results of this research might help to train maritime officers for safe navigation and to design a collision avoidance support system.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.95-102
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• 1999

Because a driver is located in the front end of KHST, he is most likely to be insured at collision accidents. So, it is very important to design some survival space for the driver. To evaluate the driver's safety of KHST (Korean High Speed Train), the front structure of power car is analysed using PAMCRASH under the SNCF accident scenario(collision against a movable rigid mass 15 ton at 110㎞/h). Because the driver's cab of KHST is a modified version of TGV-K, which is not so strong as to protect him, it turns out to be inadequate to guarantee his survival space. Therefore it is recommended to redesign the driver's cab in a crashworthy point of view like the case of TGV-Duplex or NEC.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.616-621
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• 2004

In this paper, the crush characteristics of a tilting train express (TTX) M-car design are evaluated with a head-on collision scenario. Its body shell is divided into three parts - front end, middle section, and rear end. For each part, crush-force relation is evaluated numerically through 3-dimensional shell element analysis with LS-DYNA. TTX's embody structure is a hybrid type structure made of steel and composite materials. Composite sandwich panels are modeled as layered shells whose layers have different material properties. And a damage material model is used to consider the effect of stiffness degradation during deformation. The crush characteristics obtained from these calculations will be used as material modeling data of full-rake collision analyses.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.545-552
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• 1998

A study on collision analysis of TGV-K using a 2-dimensional model is described to evaluate its crashworthiness. Two-dimensional analysis gives good information on overriding behaviour and impact forces applied to interconnecting devices such as side buffers, ball & socket joints, hooks, pins, and fingers. Since the headstock of TGV-K is not designed in a crashworthy point of view, its conceptual design fur KHST(Korean High Speed Train), under development, is suggested to improve crashworthiness. The suggested design, which adopts an energy absorber and a crashworthy headstock, is compared with the conventional headstock on dynamic behaviour to the vertical direction under the accident scenario of SNCF (collision at 110km/h against a movable rigid mass of 15 ton). It is concluded that the design modification make little difference in vertical motion. To evaluate validation of the 2-dimensional model, the results fur longitudinal motion is compared with those of 1-dimemsional one. It is found that the two results are in good agreements.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1602-1606
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• 2008

In the Rail Safety Regulations article 16, deceleration rate in the survival spaces should be limited as far as is practicable to 5g, and shall not be more than 7.5g. As it is impractical to evaluate complete train behaviour by testing, the achievement of the objectives shall be validated by dynamic simulations corresponding to the reference collisions scenarios. But initial design and evaluation procedure, impact dynamics model which classified 1D and 2D is more useful than full scale model. This paper presents acceleration response characteristics between 1D and 2D dynamics model under head-on collision in standard collision scenarios.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.32.3-33
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• 2017

Utilizing both the existing observational data for Orion A and the TRAO $^{13}CO$, $^{12}CO$ data for $1^{\circ}{\times}1^{\circ}$ region centered on M42 collected in 2012, we found a clear piece of evidence for a collision of a cloud with the OMC-1. This cloud has a shape like a long cylinder of ${\sim}0.1pc{\times}2pc$ in size, and has a well developed train of clumps of about a few solar masses, and is situated in the dark dust complex between M42 and M43. The cloud's motion is analysed to be moving at about $2.6km\;s^{-1}$, and is calculated to transverse the Orion Nebula ~2 pc above from the nebula center, toward the direction of about $60^{\circ}$ to the line of sight. This cloud had undergone a tidal splitting about a million years ago and had formed a very thin and long cylindrical core well before being engaged in the collision. General implications of this phenomenon are discussed in relation to star formation mechanisms in the GMC.

• The Journal of Korea Robotics Society
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• v.1 no.1
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• pp.81-88
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• 2006

Control of a robot manipulator in contact with the environment is usually conducted by the direct feedback control using a force-torque sensor or the indirect impedance control. In these methods, however, the control algorithms become complicated and the performance of position and force control cannot be improved because of the mechanical properties of the passive components. To cope with such problems, redundant actuation has been used to enhance the performance of position control and force control. In this research, a Double Actuator Unit (DAU) is proposed, with which the force control algorithm can be simplified and can make the robot ensure the safety during the external collision. The DAU is composed of two actuators; one controls the position and the other modulates the joint stiffness. Using this unit, it is possible to independently control the position and stiffness. The DAU based on the planetary gears is investigated in this paper. Performance using the DAU is also verified by various experiments. It is shown that the manipulator using this mechanism provides better safety during the impact with the environment by reducing the joint stiffness appropriately on detecting the collision of a manipulator.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.203-210
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• 2011

This study formulates the theoretical wheel-set model to evaluate wheel-climbing derailments of rolling stock due to collision, and verifies this theory with dynamic simulations. The impact forces occurring during collision are transmitted from a car body to axles through suspensions. As a result of combinations of horizontal and vertical forces applied to axles, rolling stock may lead to derailment. The derailment type will depend on the combinations of the horizontal and vertical forces, flange angle and friction coefficient. According to collision conditions, the wheel-lift, wheel-climbing or roll-over derailments can occur between wheel and rail. In this theoretical derailment model of wheelset, the wheel-climbing derailment types are classified into Climb-over, Climb/roll-over, and pure Roll-over according to derailment mechanism between wheel and rail, and we proposed the theoretical conditions to generate each derailment mechanism. The theoretical wheel-set model was verified by dynamic simulations.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1414-1419
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• 2011

In this paper we study the modeling to quantitatively assess the failure rate of USN system designed for fault-tolerant architecture, aiming at applying the world's best domestic USN technology to safety-critical railways. In order to apply the USN system to the safety-critical field like a train control sector that the failures of controllers may cause severe railway accidents such as train collision and derailment, the quantitative reliability and safety evaluation recommended in IEC 62278 must be preceded. We also develop the evaluation model for overall system failure rate for the distributed network structure, which is the characteristics of USN system. Especially, we allocate reliability targets to component units, and present an availability evaluation plan through the plan on the quantitative achievement of failure rate for sensor nodes, gateways, radio-communication network and servers, along with the failure rate model of the overall system considering network operational features.