• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.505-517
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• 2016

The structural integrity of a dual-purpose metal cask currently under development by the Korea Radioactive Waste Agency (KORAD) was evaluated, through numerical simulations and a model test, under high-speed missile impact reflecting targeted aircraft crash conditions. The impact conditions were carefully chosen through a survey on accident cases and recommendations from literature. In the impact scenario, a missile flying horizontally hits the top side of the cask, which is freestanding on a concrete pad, with a velocity of 150 m/s. A simplified missile simulating a commercial aircraft engine was designed from an impact loade-time function available in literature. In the analyses, the dynamic behavior of the metal cask and the integrity of the containment boundary were assessed. The simulation results were compared with the test results for a 1:3 scale model. Although the dynamic behavior of the cask in the model test did not match exactly with the prediction from the numerical simulation, other structural responses, such as the acceleration and strain history during the impact, showed very good agreement. Moreover, the containment function of the cask survived the missile impact as expected from the numerical simulation. Thus, the procedure and methodology adopted in the structural numerical analyses were successfully validated.

• Steel and Composite Structures
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• v.44 no.4
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• pp.587-602
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• 2022

In this study, the classical J₂ flow theory is explicitly proved to be inappropriate to describe the plastic behaviour of structural steels under different stress states according to the reported test results. A numerical framework of the characterization of the strain hardening and ductile fracture initiation involving the effect of stress states, i.e., stress triaxiality and Lode angle parameter, is proposed based on the mechanical response of structural steels under monotonic loading. Both effects on strain hardening are determined by correction functions, which are implemented as different modules in the numerical framework. Thus, other users can easily modify them according to their test results. Besides, the ductile fracture initiation is determined by a fracture locus in the space of stress triaxiality, Lode angle parameter, and fracture strain. The numerical implementation of the proposed model and the corresponding code are provided in this paper, which are also available on GitHub. The validity of the numerical procedure is examined through single element tests and the accuracy of the proposed model is verified by existing test results.

• Earthquakes and Structures
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• v.12 no.5
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• pp.501-513
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• 2017

To investigate the seismic performance of Y-shaped eccentrically braced frames fabricated with high-strength steel (Y-HSS-EBFs), a shake table test of a 1:2 scaled three-story Y-HSS-EBF specimen was performed. The input wave for the shake table test was generated by the ground motions of El Centro, Taft, and Lanzhou waves. The dynamic properties, acceleration, displacement, and strain responses were obtained from the test specimen and compared with previous test results. In addition, a finite element model of the test specimen was established using the SAP2000 software. Results from the numerical analysis were compared with the test specimen results. During the shake table test, the specimen exhibited sufficient overall structural stiffness and safety but suffered some localized damage. The lateral stiffness of the structure degenerated during the high seismic intensity earthquake. The maximum elastic and elastoplastic interstory drift of the test specimen for different peak ground accelerations were 1/872 and 1/71, respectively. During the high seismic intensity earthquake, the links of the test specimen entered the plastic stage to dissipate the earthquake energy, while other structural members remained in the elastic stage. The Y-HSS-EBF is a safe, dual system with reliable seismic performance. The numerical analysis results were in useful agreement with the test results. This finding indicated that the finite element model in SAP2000 provided a very accurate prediction of the Y-HSS-EBF structure's behavior during the seismic loadings.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.156-161
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• 1993

Limiting distributions of Studentized test statistics have been shown for testing the slope parameter in a simple linear structural model. Since the limiting distribution of Studentized one appears to yield inaccurate inference, this paper suggests adjustment of critical value and normalization of the Studentized one. As results, we can have procedures for refined inference based on our approximate distrbution instead of the limiting distribution.

• Journal of health informatics and statistics
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• v.42 no.2
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• pp.192-198
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• 2017

Objectives: This study was designed to construct and test the structural equation model for the alcohol-related problem of alcohol use disorders. Methods: Data were collected by structured self-questionnaires from 229 male subjects who received > 8 (greater than 8) score on Alcohol Use Disorder Identification Test (AUDIT). The Data were analyzed by SPSS 21.0 and AMOS 21.0. Results: The model fit indices for the modified hypothetical model showed Q = 2.50, GFI = 0.90, and CFI = 0.94. As a result, Life position, parent's drinking problem, and alcohol expectancy had significantly direct effect on alcohol-related problem. Alcohol expectancy also had mediator effect between life position and alcohol-related problem. Conclusions: Consequently, the more positive life position, the less alcohol-related problem occurred. It is necessary to change their life position, which is individual factor, to prevent or reduce the alcohol related problem of alcohol use disorders.

• International journal of steel structures
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• v.18 no.4
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• pp.1177-1190
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• 2018

This study presents an analytical framework for estimating the thermo-mechanical behavior of a composite beam exposed to fire. The framework involves: a fire simulation from which the evolution of temperature on the structure surface is obtained; data transfer by an interface model, whereby the surface temperature is assigned to the finite element model of the structure for thermo-mechanical analysis; and nonlinear thermo-mechanical analysis for predicting the structural response under high temperatures. We use a plastic-damage model for calculating the response of concrete slabs, and propose a method to determine the stiffness degradation parameter of the plastic-damage model by a nonlinear regression of concrete cylinder test data. To validate simulation results, structural fire experiments have been performed on a real-scale steel-concrete composite beam using the fire load prescribed by ASTM E119 standard fire curve. The calculated evolution of deflection at the center of the beam shows good agreement with experimental results. The local test results as well as the effective plastic strain distribution and section rotation of the composite beam at elevated temperatures are also investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.131-134
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• 2001

The three-dimensional precision measurement technology for industry product of middle and/or large scale has been developed. Theodolite measurement system which is one of the technology is widely used in aerospace industry. This paper describes measurement method and results for spacecraft structure test model by using the measurement system. And structural stability for STM is desribed through the comparison between design values and measured values.

• Steel and Composite Structures
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• v.5 no.4
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• pp.325-340
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• 2005

This paper presents a thorough investigation into the structural performance of cold-formed steel column bases using double lipped C sections with bolted moment connections. A total of four column base tests with different connection configurations were carried out, and it was found that section failure under combined bending and shear was always critical. Moreover, the proposed column bases were demonstrated to be structurally efficient attaining moment resistances close to those of the connected sections. In order to examine the structural behaviour of the column base connections, a finite element model was established using shell and spring elements to model the sections and the bolted fastenings respectively. Both material and geometrical non-linearities were incorporated, and comparison between the test and the numerical results was presented in details. The design rules originally developed for bolted moment connections between lapped Z sections were adopted and re-formulated for the design of column base connections after careful calibration against the test data. Comparison on co-existing moments and shear forces at the critical cross-sections of the column bases was fully presented. It was shown that the proposed design and analysis method was structurally adequate to predict the failure loads under combined bending and shear for column bases with similar connection configurations.

• Steel and Composite Structures
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• v.5 no.4
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• pp.289-304
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• 2005

This paper presents a thorough investigation into the structural performance of cold-formed steel column bases using double lipped C sections with bolted moment connections. A total of four column base tests with different connection configurations were carried out, and it was found that section failure under combined bending and shear was always critical. Moreover, the proposed column bases were demonstrated to be structurally efficient attaining moment resistances close to those of the connected sections. In order to examine the structural behaviour of the column base connections, a finite element model was established using shell and spring elements to model the sections and the bolted fastenings respectively. Both material and geometrical non-linearities were incorporated, and comparison between the test and the numerical results was presented in details. The design rules originally developed for bolted moment connections between lapped Z sections were adopted and re-formulated for the design of column base connections after careful calibration against the test data. Comparison on co-existing moments and shear forces at the critical cross-sections of the column bases was fully presented. It was shown that the proposed design and analysis method was structurally adequate to predict the failure loads under combined bending and shear for column bases with similar connection configurations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.265-269
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• 2016

In this research, the performances of active hood lift system(AHLS) are investigated according to the structural improvement through the experimental test. After introducing the working principle of the AHLS activated by a gunpowder actuator, the structural problems that cause the inefficiencies in the actuation are analyzed to reduce the deployment time of system. Sequentially, the improved structural model is proposed base on the analysis. The deployment time of AHLS are evaluated by the experimental test, and it has been identified that the improved model can provide a faster deploying time of AHLS.