• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.393-400
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• 2014

Structures are often subject to vehicle collision which can be accidental or terrorist attack. Previous research shows that the damage in major columns may result in progressive collapse of a whole building. This study investigates the performance of a steel column standing on a reinforced concrete footing subjected to a vehicle collision. The size and the axial load of the steel column are determined based on the assumption that it is the first story corner column in a typical three-story building with six meter span length. The finite element model of a eight-ton single unit truck provided by the NCAC (National Crash Analysis Center) is used in the numerical analysis. The finite element analysis is performed using the LS-DYNA, and the results show that the behavior of the column subjected to car impact depends largely on the column-foundation connection detail.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.745-748
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• 2008

The past structures were just required bearing capacity to service load, serviceability, and resistance to corrosion. However this point of view has changed after 9.11 terrorism, capacities which can bear impact loading by explosion, and heat by fire happening at the same time, become to be important as a basic condition. The blast resistance capacity of structures is very important part against all over the world is intimidated by terrorism everyday in current point of time. The target of this research is a development of segmented composites and layered structures with high blast resistance using cementitious composites, concrete and FRP composites, which has high tensile strength and ductility, to apply in not only existing facilities but also new ones. Through the improvement of blast resistance, casualties and economic loss can be minimized, and it is possible to diminish the structure collapse and delay the time of structure collapse by thermal effect, impact loading, dynamic loading and high strain.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.675-683
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• 2011

When impacts by falling objects are applied to the structures, vertical resisting member(column or column group) results in progressive collapse. By knowing clearly load-deformation relationship of a structural frame, to prevent progressive collapse by absorbing potential energy of falling objects though column groups are lost by the impact of falling object accidently. If residual strength in vertical direction exceeds vertical load, which the sum of the weight of falling objects and usual supportive vertical load as the result of absorbing released location energy, it does not result in progressive collapse. On the other hand, in case when weight of falling objects is included in usual supportive vertical load. In this paper, 1-story 4-spans model is analyzed by non-linear FEM and to examine the level of deterioration, limit analysis of 1-story 4-spans plane frame was carried out.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.243-249
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• 2014

Currently, CFRP composites are rapidly replacing steel plates, as they are lighter, stronger, and more elastic; however, they are poorly suited to hygrothermal and impact-collapsed environments because moisture can alter their molecule arrangement and chemical properties. In this study, environments are experimentally simulated in order to investigate changes in the moisture absorption inside a CFRP composite and to determine its weakest point. Moreover, changes in the moisture absorption ratio at temperatures of $60^{\circ}C$ and $80^{\circ}C$ are studied and compared in order to understand how changes in temperature affect moisture absorption inside CFRP composites. Results show that moisture absorption leads to a strength reduction of around 50%. In addition, the moisture absorption rate inside CFRP composites is shown to change rapidly with increasing temperature. Accordingly, it showed that the change in matrix also has a weak point.

• International Commerce and Information Review
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• v.12 no.3
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• pp.267-288
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• 2010

The collapse of housing market bubble in United States had a considerable impact on the world economy. The collapse of housing market bubble in United States generates the global financial crisis at the worldwide level. The housing market bubble question the efficacy of fundamental proposition of orthodox economics based on the rationality of human choice. According to neuroeconomics and neuroscience, emotion and affect play the important role in purchasing the commodity in retails market. On the basis of the neuroeconomics, this study focuses on the role of affect and emotion in the purchase of subprime loan in United States. Robert Schiller suggests that one of the causes of housing market bubble is the contagion effect of human belief in the society. The structure of this paper is as follows. First, this study investigates the mechanism of human brain and role of various neurons to influence the human behavior in the purchase of house in United States, such as Dophamine neuron and mirroring neuron. Second, this study shows the possibility that the mirror neuron might explain the contagion of human belief in housing transaction market. It can be a seed of housing market bubble. Furthermore, this study show the implications of neuroeconomics is suggestive to the negotiation process in commercial policy in United States.

• Journal of the Korea Safety Management & Science
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• v.4 no.2
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• pp.189-197
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• 2002

Composites have wide applications in aerospace vehicles and automobiles because of the inherent flexibility in their design lot improved material properties. Composite tubes in particular, are potential candidates for their use as energy absorbing elements in crashworthiness applications due to their high specific energy absorbing capacity and the stroke efficiency. Their failure mechanism however is highly complicated and rather difficult to analyze. This includes fracture in fibers, in the matrix and in the fiber-matrix interface in tension, compression and shear. The purpose of this study is to investigate the energy absorption characteristics of Gr/E(Graphite/Epoxy) tubes on static and impact tests. The collapse characteristics and energy absorption of a variety of tubes have been examined. Changes in the lay-up which increased the modulus increased the energy absorption of the tubes. Based on the test results, the following remarks can be made: Among CA15, CA00 and CA90 curves the CA90 tube exhibits the highest crush load throughout the whole crush process, and max load increases as interlaminar number increase. Among all the tubes type CC90 has the largest specific crushing stress of 52.60 kJ/kg which is much larger than other tubes.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.56-63
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• 2007

In case of bus rollover, the body structure of the bus should be designed to ensure the survival space for passengers. So, this study focuses on evaluating rollover strength through a computer simulation using the commercial code, LS-DYNA3D at the initial stage of vehicle development. For this study, section structure was modeled using a simple beam element, and impact boundary conditions required by ECE(Economic Commission for Europe) regulation No.66 were applied. In order to confirm the validity of the beam element bus model, the results compared with the test results and shell element bus model. The analysis errors from beam element bus model are due to the difference in strain energy of joint area between beam and shell model. In this study, a method for the joint modeling was suggested by using nonlinear springs to which the collapse mechanisms were applied.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.251-262
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• 2019

This paper is about design concept and simplified analysis method against dropped object events. The ships and offshore structures are exposed to various types of dropped object accidents such as laydown area struck by drill collar and topside deck hit by food container during their lifetime. Mitigation can be accomplished by proper facility layout and designing structures to safely absorb energy from accidental loads. It shall be designed to avoid loss of life, environmental pollution and loss of assets. Impact loads can lead to structural global collapse of the main structure or punching of a local barrier type structure with potential to escalate directly or indirectly to a global collapse of the structure. This study provides the background information on the issue of dropped object of the shipyard and also focuses on structural assessment of the local individual component such as deck plate, stiffener and web/girder by using simplified analysis method. The results of the simplified analysis method were compared with numerical results using non-linear finite element simulation.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1252-1252
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• 2022

Temporary work that utilizes temporary equipment (e.g., system scaffold and system pipe support) in construction work is one of the most vulnerable work from a safety perspective in South Korea. Typically, temporary equipment is reused at construction sites. The Korea Occupational Safety and Health Agency announced guidelines regarding the performance standards for reusable temporary equipment to prevent the accidental collapse of temporary facilities. Nevertheless, temporary facilities' collapse still occurs, which could be attributed to a degradation in the performance due to the reuse of temporary equipment. Therefore, this study investigated the performance of simple temporary structures assembled with new and reused equipment. To this end, an experimental module was designed based on previous research cases, and two experimental models were constructed, in which one was assembled using new equipment (Model A), and the other was built using reused equipment (Model B). To determine the performance of each model, a load test was conducted to measure the maximum load that each model could withstand. The experimental results revealed that the maximum load of Model B was 15% lower than that of Model A. This indicates that there is a meaningful performance difference between those two models. Based on this result, the authors decided to perform additional tests with more realistic models than previous ones. The new experimental module was designed to ensure compliance with the Korean design guidelines. In this presentation, the authors show details of the first tests and their results and plan for the additional test.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.297-302
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• 2020

Korea has many mountainous regions, and slope collapse that can lead to damage in road facilities and loss of lives often occurs. Rockfall-protection facilities are necessary to reduce such damages. Among these facilities, the standard Korean rockfall-protection fence is designed to resist 50 kJ of rockfall impact energy. However, the range of rockfall energy significantly varies depending on the condition of the slope, and it sometimes reaches up to 100 kJ. Thus, providing several types of standardized rockfall-protection fence is necessary to address the different rockfall impact energy for efficient response to rockfalls. This paper presents a study on standardized rockfall-protection fence for various rockfall impact energy using finite-element analysis. According to the results, standardized rockfall-protection fences against rockfall impact energy of 30 and 100 kJ were proposed and have been verified.