• Proceedings of the KIEE Conference
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.653-654
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• 2006

This paper proposes a new linear magnetic damper for absorbing shock from a crash accident involving high speed vehicles. The magnetic damper is composed of a conductive plate, a yoke and permanent magnets which are constructed to a Halbach array to improve the damping force. In order to calculate the damping force, finite element analysis(FEA) using J-Mag, a commercial FEA tool, is performed and the results are validated by the experiment. Also, the design optimization of the plate generating the eddy current causing the damping force performed to obtain the most efficient damping force. Finally, the specifications and the performance of the proposed magnetic damper are represented.

• Korean Journal of Metals and Materials
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• 제50권12호
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• pp.873-882
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• 2012

Dual Phase (DP) steel which has a soft ferrite phase and a hard martensite phase reveals both high strength and high ductility and has received increased attention for use in automotive applications. To conduct structural analysis to verify vehicle safety, highly credible experimental results are required. In this study, tensile tests were performed in a strain rate range from $10^{-4}/s$ to 300/s for Sink Roll-Less (SRL) hot-dip metal coated sheets. Collision properties were estimated through simulation by LS-DYNA using the stress-strain curve obtained from the tensile test. The simulation results were compared with the actual crash test results to confirm the credibility of the simulation. In addition, a tensile test and a crash test with 2% prestrain and a baking (PB) specimen were evaluated identically because automotive steel is used after forming and painting. The mechanical behaviors were improved with an increasing strain rate regardless of the PB treatment. Thus, plastic deformation with an appropriate strain rate is expected to result in better formability and crash characteristics than plastic deformation with a static strain rate. The ultimate tensile strength (UTS) and absorbed energy up to 10% strain were improved even though the total elongation decreased after PB treatment, The results of the experimental crash test and computer simulation were slightly different but generally, a similar propensity was seen.

• Proceedings of the KSME Conference
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• 대한기계학회 2004년도 춘계학술대회
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• pp.456-461
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• 2004

The dynamic behavior of sheet metals must be examined to ensure the impact characteristics of auto-body by a finite element method. An appropriate experimental method has to be developed to acquire the material properties at the intermediate strain rate which is under 500/s in the crash analysis of auto-body. In this paper, tensile tests of various different steel sheets for an auto-body were performed to obtain the dynamic material properties with respect to the strain rate which is ranged from 0.003/sec to 200/sec. A high speed material testing machine was made for tension tests at the intermediate strain rate and the dimensions of specimens that can provide the reasonable results were determined by the finite element analysis. Stress-strain curves were obtained for each steel sheet from the dynamic tensile test and used to deduce the relationship of the yield stress and the elongation to the strain rate. These results are significant not only in the crashworthiness evaluation under car crash but also in the high speed metal forming.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제17권2호
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• pp.263-278
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• 2019

Since the 1970s, aircraft crash accidents have been considered as one of the severest external events that should be evaluated for license application of nuclear reactors. After the 9.11 terrorist attacks, many countries have performed safety assessment against intentional or targeted aircraft crashes into nuclear related facilities. In some countries, assessment against targeted aircraft crash was enforced by regulation and considered an important task for license approval. Safety assessment against aircraft crash is a technically difficult task and many countries manage R&D programs to improve its reliability. In this paper, regulations of many countries regarding safety assessment against aircraft crash are summarized, separating regulations for accident aircraft crash and those for targeted aircraft crash. Research performed in various countries on safety assessment of nuclear facility against aircraft crash are summarized, with a focus on spent nuclear fuel dry storage facilities.

• Proceedings of the KSR Conference
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.511-518
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• 1999

Though not very often, a train accident can cause large number of fatality. As a result, public concern about its safety is increasing nowadays. Tn this paper, the structural crashworthiness of Korean High Speed Train trailer was examined through FE analysis. Crash analyses on energy absorbing part and safety zone were carried out to determine each section force. Rollover analysis was performed to observe the amount of intrusion in the passenger's area in case of rollover accident.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권7호
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• pp.4950-4959
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• 2015

The importance of public infrastructures' protection against crash or blast loads has been emerging issue as structures are becoming bigger and population densities in downtown cities are growing up. However, there exists no sufficient study which considers the developments of protective building materials, that are essential for protective design and construction. To assess the protection performance and the applicability as protective materials of high performance fiber reinforced cementitious composites(HPFRCC), this study performed the impact tests with 40 mm gas-gun propelled projectile crash machine. From this study, it has observed that both high compressive strength of cement matrix and fiber reinforcement are beneficial for the improvement of impact resistance.

• Proceedings of the KSR Conference
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1182-1188
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• 2011

By storing various train information in running high speed train, we can analyze the cause of train accident efficiently. we have developed the smart and high available control method to control and manage the hardware modules. The hardware modules for event recorder consist CPU, Digital Input and Output, Pulse Input, Communication, Control Panel and Crash Protected Memory. The real time operation system is used to totally control and manage the various hardware modules. The main function of control method is collection of train information, calculation of train speed, interface with other on-board control system, storing and retrieving train information, and communication with Control Panel. In Control Panel, it displays the current train speed and the status of event recorder effectively. Also user interface is provided in Control Panel.

• Journal of Auto-vehicle Safety Association
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• 제10권2호
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• pp.6-12
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• 2018

Optimized section shape of aluminum bumper backbeam for enhancing the front high speed crashworthiness was investigated. Front body analysis model of a convertible vehicle was built up and parameter studies were carried out with changing the inner rib shape and the section thickness distribution. First an inner rib shape displaying most efficient structural performance was selected. Next, for the selected section the effect of section thickness combination was examined. Also, a light weighed backbeam section displaying crash performance over the current design was suggested. Finally RCAR front low speed impact analyses were carried out for the optimized models.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.173-180
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• 2004

An intensive study was conducted for the crash worthy structural design of the recently developed Korean High Speed Train (KHST). Two main design concepts were set up to protect both crews and passengers from serious injury in heavy collision accidents, and to reduce damage to the train itself in light collision accidents. A collision against a movable 15-ton rigid obstacle at 110 kph was selected from train accident investigations as the accident scenario for the heavy collisions. A train-to-train collision at the relative velocity of 16 kph was used for the light collision. The crashworthiness behaviors of KHST were numerically evaluated using FEM. Analysis results using 1-D collision dynamics model of the full rake consist and 3-D shell element model of the front end structure showed good crashworthy responses in a viewpoint of structural design. Occupant analyses and sled tests demonstrated that KHST performed well enough to protect occupants under the considered accident scenarios. Finally our numerical approaches were evaluated by a real scale collision test.

• Proceedings of the KSR Conference
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.385-392
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• 1998

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using simple model for the crashworthiness of motorized trailer of high speed train. The simple model, with very short modeling time and reduced computation time was adopted to extract the global behaviour and to perform a pre-optimization of the considered structure. Firstly, various types of crash events are investigated and the conditions for numerical simulation are defined. The simple model, using the beam and non-linear spring element, and shell element model are used to evaluated energy absorption and deformation mechanism in analyses. And aluminum is applied to real model after verification with square tube analyses. Finally, loading path and energy absorption of main components are evaluated. The analyses are aimed to ensure the crashworthiness design of high speed train.