• Computers and Concrete
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• v.14 no.6
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• pp.767-783
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• 2014

The use of composite materials to strengthen reinforced concrete (RC) structures against blast terror has great interests from engineering experts in structural retrofitting. The composite materials used in this study are rigid polyurethane foam (RPF) and aluminum foam (ALF). The aim of this study is to use the RPF and the ALF to strengthen the RC panels under blast load. The RC panel is considered to study the RPF and the ALF as structural retrofitting. Field blast test is conducted. The finite element analysis (FEA) is also used to model the RC panel under shock wave. The RC panel performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the proposed numerical model. The composite materials improve the RC panel performance under the blast wave propagation.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.241-247
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• 1999

This study presents the structural analysis of car a seat frame by the finite element method. The load-deformation characteristics of seat frame are simulated according to the test requirements by FMVSS. Three dimensional modeling technique is applied to the components of the seat frame. The shell, solid , gap and rigid elements are employed to model the car seat frame assembly. Numerical results show that the recliner and kunckle plate are identified as the possible weak part of frame, and the results are well consistent with the experimental static load test. The current analysis model can provide useful informations to design a new car seat and can reduce the overall design cost and time.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.217-224
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• 1999

This Paper shows the results of a series of model tests on the behavior of single rigid Pile, which subjected to lateral load, in non-homogeneous Nak-Dong River sands, consisted of two layers, upper and lower layers. The purpose of the present paper is to investigate the effect of ratio of lower layer thickness to embedded pile length ratio of soil modules of upper to lower layer (E$\sub$h1//E$\sub$h2/) and pile head constraint condition on the characteristics of lateral behavior of single pile. These effects can be quantified only by the results of model tests. As a model test result, in non-homogeneous sand, it shows that the lateral behavior depends upon the ratio of soil modules of upper to lower layer more than other factors. And, in respect of deflection, it was found that the reduction ratio of deflection by pile head fixity is the value of 0.5 and 0.6 for E$\sub$h1//E$\sub$h2/=0.18 and E$\sub$h1//E$\sub$h2/=5.56, respectively. The critical thickness of lower layer on the change of deflection is about 25 - 50% of pile embedded length. Also, in respect of maximum bending moment it was found that the reduction ratio of maximum bending moment by pile head fixity is the value of 0.55 and 0.7 for E$\sub$h1//E$\sub$h2/=0.18 and E$\sub$h1//E$\sub$h2/=5.56, respectively.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.198-203
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• 2008

In the present study, the deformation behavior of both of metal and polymer combination on impact was investigated. They have showed a different deformation behavior when the co-axially combined projectile was impacted on rigid target. The theory according to Taylor's simplified approach assumes an ideally rigid-plastic material model exhibiting rate-independent behavior and simple one-dimensional wave propagation concepts that neglect radial inertia. In the case of impact with polymeric materials, elastic strain in general are not negligible compared with plastic strain; and the rigid-plastic material behavior assumed by Taylor for metallic materials cannot be applied any more. Since, the sleeve and the core materials have widely different mechanical properties, they will produce a significant difference of mechanical impedance with each other. Therefore these impedance mismatch influences on the deformation behavior sleeved polymer projectile on impact. As a result, sleeved projectiles will generate a very interesting impact behavior. Therefore, the according to sleeved metal material and core polymer material can see expected. The objective of this study was to investigate the factors which influences on deformation behavior pattern of sleeve materials surface.

• Composites Research
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• v.28 no.2
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• pp.52-57
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• 2015

Soft morphing robotics making use of smart material and based on biomimetic principles are capable of continuous locomotion in harmony with its environment. Since these robots do not use traditional mechanical components, they can be built to be light weight and capable of a diverse range of locomotion. This paper illustrates a flexible smart phone robot made of smart soft composite (SSC) with inchworm-like locomotion capable of two-way linear motion. Since rigid components are embedded within the robot, bending actuators with embedded rigid segments were investigated in order to obtain the maximum bending curvature. To verify the results, a simple mechanical model of this actuator was built and compared with experimental data. After that, the flexible robot was implemented as part of a smart phone robot where the rigid components of the phone were embedded within the matrix. Then, experiments were conducted to test the smart phone robot actuation force under different deflections to verify its load carrying capability. After that, the communication between the smart phone and robot controller was implemented and a corresponding phone application was developed. The locomotion of the smart phone robot actuated through an independent controller was also tested.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.466-477
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• 2021

There are three different well-known methods for predicting the manoeuvrability of ships: (1) free running model test, (2) direct manoeuvring simulation using CFD and (3) system-based manoeuvring simulation. In this paper, the manoeuvrability of the KVLCC2 was estimated using CFD with rigid body motion and body force propeller method. The free running manoeuvre at the different time steps were also simulated. The yaw checking ability and the turning ability of KVLCC2 were predicted using CFD and could have been confirmed that the IMO criteria was satisfied. When the results were compared with the model test and system-based method, the free running simulation showed better agreement to that of the model test. It could also be confirmed that the results vary depending on the time step. Overall, the CFD results using the body force propeller method estimated most accurately the test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1577-1584
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• 2002

This paper develops a finite element model for studying the occupant behavior and injury cofficients of a large-sized cab-over type truck. Since it does not have a room to absorb collision energy and deformation in front of the passenger compartment the deformation is directly transmitted to the passenger compartment. Moreover, since its steering column is attached on the frame, severe deformation of the frame directly affects on the steering wheel's movement. Therefore, if the occupant behavior and injury coefficients analysis is performed using a finite element model developed based on a sled test, it is very difficult to expect acquiring satisfactory results. Thus, the finite element model developing in this paper is based on the frontal crash test in order to overcome the inherent problems of the sled test based model commonly used in the passenger car. The occupant behavior and injury coefficients analysis is performed using PAM-CRASH installed in super-computer SP2. In order to validate the reliability of the developed finite element model, a frontal crash test is carried out according to a test method used fur developing truck occupant's secondary safety system in european community and japan. That is, test vehicle's collision direction is vertical to the rigid barrier and collision velocity is 45kph. Thus, measured vehicle pulses at the lower parts of the left and right B-pilla., dummy chest and head deceleration profiles, HIC(head injury criterial) and CA(chest acceleration) values, and dummy behavior from the frontal crash test are compared to the analysis results to validate reliability of the developed model.

• Structural Engineering and Mechanics
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• v.84 no.1
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• pp.35-48
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• 2022

This paper investigates the artificial neural network (ANN) to predict the dimensionless parameters for contact pressures and contact lengths under the rigid punch, the initial separation loads, and the initial separation distances of a contact problem. The problem consisted of two elastic infinitely layers (EL) loaded by means of a rigid cylindrical punch and resting on a half-infinite plane (HP). Firstly, the problem was formulated and solved theoretically using the Theory of Elasticity (ET). Secondly, the contact problem was extended based on the ANN. External load, the radius of punch, layer heights, and material properties were created by giving examples of different values used at the training and test stages of ANN. Finally, the accuracy of the trained neural networks for the case was tested using 134 new data, generated via ET solutions to determine the best network model. ANN results were compared with ET results, and well agreements were achieved.

• Journal of Auto-vehicle Safety Association
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• v.8 no.3
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• pp.33-38
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• 2016

Recently, development in vehicle safety could increase interest in children's safety in vehicle collisions. But the research of children safety in vehicle collisions is not being conducted as many as that of adult's. Especially the study for the vehicle crash was not much. This study focused on the comparison of child safety between test protocols to evaluate children's safety in crash test. Injuries of Q6 and Q10 dummy were evaluated using FFRB (Full frontal rigid barrier) test and 40% ODB (Offset deformable barrier) test with one model vehicle. Even though the limit number of test, the tendency of injury criteria of Q6 and Q10 dummy between the test protocols was not conformed but injury criteria of Q6 and Q10 were not same between FFRB and 40% ODB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3013-3022
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• 2013

Satisfying the large car impact condition of the high level SB5-B for "SMART Highway" longitudinal barriers, the possibility of increase of the small car impact velocity from 120km/h to 130km/h was investigated. Through computer simulation using input parameters calibrated to full-scale crash test results, various longitudinal semi-rigid barrier models were improved such that for the small car impact speed of 120km/h the change of longitudinal and transverse velocities of the impact vehicle can satisfy the THIV limit. The barrier model determined through this process satisfied the performance assessment criteria for SB5-B impact conditions. Varying the wing angle of slip block-outs of the passed barrier model, the possibility of increase of the small car impact velocity was investigated by FEA and a full-scale crash test was conducted. It has been shown that the possibility to increase the small car impact speed to 130km/h is high if the test facility condition for 130km/h impact velocity is better equipped.