• Journal of the Korean Society for Railway
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• v.8 no.3
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• pp.253-259
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• 2005

This paper describes 3D Dimensional Measurement(EDM testing) and tensile testing results of carbody structure for crashed EMU(Electric Multiple Units). Tensile tests were performed on two different types of specimens in order to evaluate the strength changes before and after damages, obtained from plastic deformed area and nondeformed region of the crashed EMU. And Structural analysis of EMU was performed for the criteria of safety assessment. Structural analysis using commercial I-DEAS software provided important information on the stress distribution and load transfer mechanisms as well as the amount of damages during rolling stock crash. The testing results have been used to provide the critical information for the criteria of safety diagnosis.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.145-155
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• 2012

PURPOSES: This study proposes a novel method based on microscopic simulation models to evaluate bicycle passing ways in mixed traffic flow conditions at signalized intersections. METHODS: Both operational efficiency and safety are taken into consideration in the evaluation. A widely used performance measure, delay, is used for evaluating the operational efficiency. Regarding the safety evaluation, surrogate safety measures (SSM) to represent traffic conflicts and the level of crash severity, DeltaS and Max.DeltaV, are applied in the proposed method. RESULTS: Extensive simulations and statistical tests show that an integrated bike-box way is identified as the best in terms of operational efficiency and safety. CONCLUSIONS: The proposed method and outcomes of this study will be valuable for bicycle traffic operations and facility design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.523-524
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• 2006

It is necessary to have a model that describes the anthropometry of the crash victim with a sufficient accuracy Koreans, however, do not have their own pedestrian dummies to be used in pedestrian collision tests. They have to use European and American dummies for their safety analysis. In this study scaled pedestrian dummies were constructed by using MADYMO. The dummies represent Korean average males and females aged from 25 to 29. The scaled Korean dummies and MADYMO human models were used to obtain and compare the pedestrian dynamic behaviors and injury criteria during the impact events.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.128-133
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• 2008

In this paper, a new technique was suggested to estimate vehicle speed for the traffic accident reconstruction, and accident investigators can estimate initial vehicle speed based on this suggested technique. Turning tests with several vehicle speeds were executed and compared with the motion of the vehicle and the shape of the tire marks. A new method for estimating the coefficient of friction is suggested by using the longitudinal and lateral components of tire marks. And also, a speed calculation graph is suggested to estimate vehicle speed for traffic accident reconstruction.

• Journal of Auto-vehicle Safety Association
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• v.7 no.1
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• pp.40-44
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• 2015

In recent years, WorldSID dummy has been continuously developed and investigated to be a better represent biolfidelic ATD as well as a device for replacement of the current existing EuroSID-2. In Korea, the side impact accident is one of the major severe accidents in terms of numbers of accidents and fatality. Since 2003, 50kph 90degree side crash test has been initiated as a safety standard with EuroSID-1 at the first stage and also same time 55kph impact speed test has been conducted as a part of KNCAP program. Currently only EuroSID-2 is accepted as a regulatory tool for vehicle certification and KNCAP. In order to make use of WorldSID of KNCAP in the distant futuer the tests with WorldSID is conducted experimentally.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.8-13
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• 2008

The fuel tank systems of fixed wing and rotary wing aircrafts require the self-sealing and crash-worthiness for their survivability. For these requirements, the flexible composite fuel tank is generally used. In this study, the drop and penetration performance of a fuel tank is investigated. The FE simulation includes the drop and penetration test of a fuel tank using MSC.DYTRAN. MSC.DYTRAN can provide the fluid-structure modeling of these test from Euler and Lagrange grids. Using MSC.DYTRAN, the finite modeling of the test cube of the flexible fuel tank and its FE simulation are performed for various environments. The simulation results can show if the test cube satisfies the performance requirements of the fuel tank.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.820-825
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• 2008

In the article 16 of the domestic rolling stock crashworthiness regulations, the collision acceleration level during collision accidents should remain under the maximum 7.5g and the average 5g. By the way, the accelerations obtained in crash simulations and tests contain many kinds of high frequency components due to numerical oscillations or noisy signals. So, this paper aims to develop reliable post-processing methods to filter high frequency oscillations and extract the rigid body motions of passenger rail cars. For this study we used the 1-dimensional dynamic model of KHST (Korean high-speed train), and evaluated acceleration data at the driver's area in the first power car and the passenger area in the following trailer.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1035-1040
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• 2004

In the proto design stage of a new car, the performance of an occupant protection system is often evaluated by CAE instead of the real test. CAE predicts and recommends the appropriate design values hence reducing the number of the real tests. However, the existing researches using CAE in predicting the performances do not consider the uncertainties of parameters, in which inconsistency between the actual test results and CAE exists. In this research, the optimization procedure of a protection system such as airbag and load limiter is suggested for the frontal collision. The DACE modeling known as Kriging interpolation is introduced to obtain the meta model of the system followed by the tabu search method to determine a global optimum. Finally, the distribution of a suggested design is determined through the Monte-Carlo Simulation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.614-620
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• 2009

A fuel tank of a vehicle is an important part due to its flammable contents ant its importance during crash conditions. Therefore, the fuel tank's design should be assessed for durability and robustness to ensure safety during the early development phase. Previously, evaluation for the durability was done by testing in physical driving conditions which could only be done after the completion of the vehicle. Computation simulation is a more effective method to evaluate the strength and durability of the fuel tank during the early stage. In this paper, two outstanding computational simulation methods are studied. One evaluates PV cycle fatigue due to build up pressure in the fuel tank and the other evaluates the PSD vibration fatigue from modal characteristics. The results show that computational methods agree with physical tests and are thus suitable to analyze the strength and durability of the fuel tank at early development phase.

• Korean Journal of Metals and Materials
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• v.56 no.11
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• pp.787-795
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• 2018

The effects of tempering condition on the microstructure and mechanical properties of 30MnB5 hot stamping steel were investigated in this study. Before the tempering, hot-stamped 30MnB5 steel was composed of only ${\alpha}^{\prime}$-martensite microstructure without precipitates. After the tempering at $180^{\circ}C$ for 120 min, nano-sized ${\varepsilon}$-carbides were precipitated in the ${\alpha}^{\prime}$-martensite laths. After tempering at $250^{\circ}C$ for 60 min, cementite was precipitated along the ${\alpha}^{\prime}$-martensite lath boundaries. The cementite was also observed in the specimens tempered at $350^{\circ}C$ for 30 min and $450^{\circ}C$ for 6 min, respectively. The globular ${\alpha}$-ferrite appeared at $350^{\circ}C-30min$ tempering, and the volume fraction of ${\alpha}$-ferrite increased when the tempering temperature was increased. The yield strength increased after tempering, and it reached a peak with the tempering condition of $180^{\circ}C-120min$, due to the nano-sized precipitates in the ${\alpha}^{\prime}$-martensite lath. After the tempering, the steel's ultimate tensile strength (UTS) was decreased due to the reduction in dislocation density and C segregation to lath boundaries. The highest elongation was observed at the $180^{\circ}C-120min$ tempering condition, due to the reduction of residual stress, and the lack of precipitates along the lath boundaries. The $180^{\circ}C-120min$ tempering condition was considered to have outstanding crash performance, according to toughness and anti-intrusion calculation results. In drop tower crash tests, the 30MnB5 door impact beam tempered at $180^{\circ}C$ for 120 min showed better crash performance compared to a 22MnB5 door impact beam.