• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.226-232
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• 2000

This paper develops a finite element model for studying the crashworthiness analysis of a mid-size truck. A simulation for a truck frontal crash to a rigid barrier using the model is performed with PAM-CRASH installed in super computer SP2. Full vehicle model is composed of 86467 shell elements, 165 beam elements and 98 bar elements, and 86769 nodes. The model uses four material model such as elastic, elastic-plastic(steel), rigid and elastic-plastic(rubber) material model which are in PAM-CRASH. Frame and suspension system are modeled with 28774 shell elements and 31412 nodes. Cab is modeled with 34680 shell elements and 57 beam elements, and 36254 nodes. Bumper is modeled with 2262 shell elements, and 2508 nodes. Axle, steering shaft, etc are modeled using beam or bar elements. Mounting parts are modeled using rigid bodies. Bodies are interconnected using nodal constrains or joint options. To verify the developed model, frontal crash test with 30mph velocity to a rigid barrier is carried out. In the crash test, vehicle pulse at lower part of b-pillar is measured, and deformed shapes of frame and driver seat area are photographed. Those measured vehicle pulse and photographed pictures are compared those from the simulation to verify the developed finite element model.

• Structural Engineering and Mechanics
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• v.89 no.3
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• pp.309-321
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• 2024

In this paper, the effect of semi-rigid connections on the stability bearing capacity of cross-bracings in steel tubular transmission towers is investigated. Herein, a prediction method based on the hybrid model which is a combination of particle swarm optimization (PSO) and backpropagation neural network (BPNN) is proposed to accurately predict the stability bearing capacity of cross-bracings with semi-rigid connections and to efficiently conduct its probabilistic assessment. Firstly, the establishment of the finite element (FE) model of cross-bracings with semi-rigid connections is developed on the basis of the development of the mechanical model. Then, a dataset of 7425 samples generated by the FE model is used to train and test the PSO-BPNN model, and the accuracy of the proposed method is evaluated. Finally, the probabilistic assessment for the stability bearing capacity of cross-bracings with semi-rigid connections is conducted based on the proposed method and the Monte Carlo simulation, in which the geometric and material properties including the outer diameter and thickness of cross-sections and the yield strength of steel are considered as random variables. The results indicate that the proposed method based on the PSO-BPNN model has high accuracy in predicting the stability bearing capacity of cross-bracings with semi-rigid connections. Meanwhile, the semi-rigid connections could enhance the stability bearing capacity of cross-bracings and the reliability of cross-bracings would significantly increase after considering semi-rigid connections.

• Geomechanics and Engineering
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• v.9 no.2
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• pp.243-259
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• 2015

Comparative study has been performed to investigate the behavior of dredged fills on rigid (Model 1) and flexible (Model 2) containers. The study was focused on the sedimentation of soil fills and the development of total stresses. Model 1 is made of an acrylic cylinder and Model two is a scale-size geotextile tube. Results indicate that for rigid containers, significant decrease of the sediment height is apparent during the dewatering process. On the other hand, because the geotextile is permeable, the water is gradually dissipated during the filling process on flexible containers. Hence, significant loss in the tube height is not apparent during the duration of the test. Pressure spikes are apparent on rigid containers during the filling process which can be attributed to the confining effect due to hydrostatic pressure. For the flexible containers, the pressure readings gradually increases with time during the filling process and normalize at the end on the filling stage. No pressure spikes were apparent due to the gradual dissipation of pore water pressure.

• Journal of Industrial Technology
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• v.34
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• pp.45-52
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• 2014

In this paper the settlement characteristic of shallow foundation on sandy soil overlained by rigid ground was investigated by analyzing results of model tests. For model experiments, model tests were performed with sandy soils sampled from the field, changing the relative density of sandy soil and the ratio of thickness of sandy layer(H) to the width of model strip footing(B). As result of tests, settlement of sandy soils increases as the value of H/B increases, whereas it increases with relative density of soil. Bearing capacity decreases as the thickness of the sand layer relative to the footing width increases. In order to analyze the settlement characteristics of sandy ground, the results of model tests were compared with the predicted values using the empirical formulas proposed by Terzaghi, De Beer and Schmertmann. The method by De Beer was found to be in good agreements with test results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1114-1119
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• 1995

This paper presents the development of estimation model and control method based on the new computer vision. This proposed control method is accomplished using a sequential estimation scheme that permits placement of the rigid body in each of the two-dimensional image planes of monitoring cameras. Estimation model with six parameters is developed based on a model that generalizes known 4-axis scara robot kinematics to accommodate unknown relative camera position and orientation, etc. Based on the estimated parameters,depending on each camers the joint angle of robot is estimated by the iteration method. The method is tested experimentally in two ways, the estimation model test and a three-dimensional rigid body placement task. Three results show that control scheme used is precise and robust. This feature can open the door to a range of application of multi-axis robot such as assembly and welding.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.100-107
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• 1998

This paper presents the development of estimation model and control method based on the new robot vision. This proposed control method is accomplished using the sequential estimation scheme that permits placement of the rigid body in each of the two-dimensional image planes of monitoring cameras. Estimation model with six parameters is developed based on the model that generalizes known 4-axis scara robot kinematics to accommodate unknown relative camera position and orientation, etc. Based on the estimated parameters, depending on each camera the joint angle of robot is estimated by the iteration method. The method is experimentally tested in two ways, the estimation model test and a three-dimensional rigid body placement task. Three results show that control scheme used is precise and robust. This feature can open the door to a range of application of multi-axis robot such as assembly and welding.

• Journal of the Korean Wood Science and Technology
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• v.23 no.3
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• pp.40-47
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• 1995

This study was carried out to develop a finite element analysis model that considers the semi-rigid characteristics of a wood-dowel joint, which is different from conventional joints that are used in the field of engineering. Wood-dowel joints are classified as semi-rigid joints that possess the following characteristics: (1) they are less stiffer than rigid joints and (2) their stiffness is determined by the dowel's diameter, depth of dowel embedment in the face member and quantity of pin dowels. In this study a finite element model that considers the changes in stiffness according to the above mentioned factors was developed and its suitability was verified by experiments using a wood-dowel joint test specimen made up of particleboards. After comparing the experimental results and the analysis results of the wood-dowel joint which was applied with the proposed finite element model, less than 10% of error was found which is considered to be negligibly small. Hence this shows that this proposed finite element model can be used to predict deformation of wood-dowel joints.

• Structural Engineering and Mechanics
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• v.82 no.6
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• pp.735-745
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• 2022

The suspension thyristor valve can generate tremendous vertical acceleration responses in layers and large tension forces in hangers. A shaking table test of a scaled-down model of thyristor valves suspended on a hall building is performed to qualify the risk of vertical uplift of two representative types of valves, the chain valve and the rigid valve. Besides, an analytical model is established to investigate the source of the slackening of hangers. The test results show that the valves frequently experience a large vertical acceleration response. The soft spring joint can significantly reduce acceleration, but is still unable to prevent vertical uplift of the chain valve. The analytical model shows a stiffer roof and inter-story connection both contribute to a higher risk of vertical uplift for a rigid valve. In addition, the planar eccentricity and short hangers, which result in torsional motion of the valve, increase the possibility of vertical uplift for a chain valve. Therefore, spring joints with additional viscous dampers and symmetric layout in each layer are recommended for the rigid and chain valve, respectively, to prevent the uplift of valves.

• Journal of Industrial Technology
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• v.18
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• pp.405-415
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• 1998

This thesis is an experimental and numerical research on bearing capacity acting retaining walls close to rigid slopes with stiff angles. Experiments were performed with changing the roughness of adjacent slope to the wall, its inclination, distance between wall and slope. Vertical stress and applied surcharge loads were measured by miniature earth cells and a load cel respectively. Stress distribution Vertical Settlement of surcharge load of rigid model footing were measured by LVDTs. Bearing capacities of surcharge loads were compared with theoretical estimations by using several different methods of limit equilibrium and numerical analysis. For limit equilibrium methods, the modified silo and the wedge theories, proposed by Chung sung gyo and Chung in gyo (1994) were used to analyze test results Based on those modified theories, the particular solution with the boundary condition of surcharge loads on the surface of backfill was obtained to find the stress distributions acting in the backfill and to compare with test results. From results of surcharge test with model wall being very close to the slope, analyzed results by the modified silo theory and to be in the better agreements than other methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.73-79
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• 1998

For the design and development of the wheel type excavator, the dynamic effects of travelling on the performance of the equipment should be first analyzed and conside- red in the initial design stage. In order to test the durability of the equipment in a short period, th travelling test should be performed over accelerated durability test tracks. which is more severe than general field roads such as city road, paved road, unpaved road and rough road. In this paper, a parametric study is performed in order to determine important design parameters of durability test track of a wheel type excavator. A rigid body model is developed using DADS and dynamic analysis is performed for the equipment travelling over several test roads with different severity. A comparison of test and analysis results is also presented.