• Nuclear Engineering and Technology
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• v.46 no.1
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• pp.73-80
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• 2014

A concrete cask is an option for spent nuclear fuel interim storage. A concrete cask usually consists of a metallic canister which confines the spent nuclear fuel assemblies and a concrete overpack. When the overpack undergoes a missile impact, which might be caused by a tornado or an aircraft crash, it should sustain an acceptable level of structural integrity so that its radiation shielding capability and the retrievability of the canister are maintained. A missile impact against a concrete overpack produces two damage modes, local damage and global damage. In conventional approaches [1], those two damage modes are decoupled and evaluated separately. The local damage of concrete is usually evaluated by empirical formulas, while the global damage is evaluated by finite element analysis. However, this decoupled approach may lead to a very conservative estimation of both damages. In this research, finite element analysis with material failure models and element erosion is applied to the evaluation of local and global damage of concrete overpacks under high speed missile impacts. Two types of concrete overpacks with different configurations are considered. The numerical simulation results are compared with test results, and it is shown that the finite element analysis predicts both local and global damage qualitatively well, but the quantitative accuracy of the results are highly dependent on the fine-tuning of material and failure parameters.

• Structural Engineering and Mechanics
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• v.69 no.6
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• pp.677-691
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• 2019

In recent years, interest is growing in the engineering community on the experimental assessment and the theoretical prediction of the out-of-plane (OOP) seismic response of unreinforced masonry (URM) infills, which are widespread in Reinforced Concrete (RC) buildings in Europe and in the Mediterranean area. In the literature, some mechanical-based models for the prediction of the entire OOP force-displacement response have been formulated and proposed. However, the small number of experimental tests currently available has not allowed, up to current times, a robust and reliable evaluation of the predictive capacity of such response models. To enrich the currently available experimental database, six pure OOP tests on URM infills in RC frames were carried out at the Department of Structures for Engineering and Architecture of the University of Naples Federico II. Test specimens were built with the same materials and were different only for the thickness of the infill walls and for the number of their edges mortared to the confining elements of the RC frames. In this paper, the results of these experimental tests are briefly recalled. The main aim of this study is comparing the experimental response of test specimens with the prediction of mechanical models presented in the literature, in order to assess their effectiveness and contribute to the definition of a robust and reliable model for the evaluation of the OOP seismic response of URM infill walls.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.95-104
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• 2019

The Standard ASCE 61-14 proposes the Substitute Structure Method (SSM) as a Nonlinear Static Procedure (NSP) to estimate nonlinear displacement demands at the center of mass of piers or wharves under seismic actions. To account for bidirectional earthquake excitation according to the Standard, results from independent pushover analyses in each orthogonal direction should be combined using either a 100/30 directional approach or a procedure referred to as the Dynamic Magnification Factor, DMF. The main purpose of this paper is to present an evaluation of these NSPs in relation to four wharf model structures on soil conditions ranging from soft to medium dense clay. Results from nonlinear static analyses were compared against benchmark values of relevant Engineering Design Parameters, EDPs. The latter are defined as the geometric mean demands that are obtained from nonlinear dynamic analyses using a set of 30 two-component ground motion records. It was found that SSM provides close estimates of the benchmark displacement demands at the center of mass of the wharf structures. Furthermore, for the most critical pile connection at a landside corner of the wharf the 100/30 and DMF approaches produced displacement, curvature, and force demands that were reasonably comparable to corresponding benchmark values.

• Journal of Auto-vehicle Safety Association
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• v.10 no.4
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• pp.54-59
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• 2018

While the advanced trffic environment systems are developed recently, the traffic systems for transportation vulnerable are still under development and their social life are limited as well. In order to the secure their mobility rights, it had been required to set up the particular system for the traffic welfare. One of the significant items is the express bus operation for wheelchair users. Thus, the research of development and operation for express buses with wheelchair users was funded by the Korean government. Before the express bus development for wheelchair users based on the current bus model, this study set up the evaluation method for the bus rollover characteristics to ensure occupant safety using the finite element method. The partial bus model was developed corresponding to the full bus model response under rollover event and the evaluation method based on two model (full bus model and partial bus model) responses is planned to apply the model development of express bus modification for wheelchair users.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.35-42
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• 2021

An experimental study was carried out to evaluate the shear performance at the interface composed of structural laminates and concrete. The main variables are the number of CLT layers and the shape of the shear connector. The number of CLT layers consisted of 3 and 5 layers. A total of 6 test specimens for shear performance evaluation were prepared in the form of a shear connector, a direct screw type and a vertically embedded type. As a result of the experiment, similar behavior was shown in all specimens, regardless of the number of layers, including direct screw type (SC series) and vertically embedded type (VE series). The behavior at the joint surface was damaged due to the occurrence of initial shear cracks, expansion of shear groove cracks, and splaying at the interface after the maximum load.After the maximum load, the shear strength decreased gradually due to the effect of the shear connector. It can be seen that the shear strength of all specimens is determined by shear and compression stress failure of concrete at the interface of the notch joint.

• Wind and Structures
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• v.31 no.6
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• pp.575-591
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• 2020

Wind load is typically considered as one of the governing design loads acting on a structure. Understanding its nature is essential in evaluation of its action on the structure. Many codes and standards are founded on state of the art knowledge and include step by step procedures to calculate wind loads for various types of structures. One of the most accepted means for calculating wind load is using Gust Load Factor or base bending Moment Gust Load Factor (MGLF), where codes are adjusted based on local data available. Although local data may differ, the general procedure is the same. In this paper, ASCE 7-16 (2017), which is used as the main reference in the U.S., and Korean Building Code (KBC 2016) are compared in evaluation of wind loads. The primary purpose of this paper is to provide insight on each code from a structural engineering perspective. Herein, discussion focuses on where the two codes are compatible and differ. In evaluating the action of wind loads on a building, knowledge of the dynamic properties of the structure is critical. For this study, the design of four figurative high-rise buildings with dual systems was analyzed.

• Transactions of Materials Processing
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• v.31 no.4
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• pp.229-239
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• 2022

Convolution Neural Network(CNN) is a class of deep learning algorithms and can be used for image analysis. In particular, it has excellent performance in finding the pattern of images. Therefore, CNN is commonly applied for recognizing, learning and classifying images. In this study, the surface defect classification performance of Al 6061 extruded material using CNN-based algorithms were compared and evaluated. First, the data collection criteria were suggested and a total of 2,024 datasets were prepared. And they were randomly classified into 1,417 learning data and 607 evaluation data. After that, the size and quality of the training data set were improved using data augmentation techniques to increase the performance of deep learning. The CNN-based algorithms used in this study were VGGNet-16, VGGNet-19, ResNet-50 and DenseNet-121. The evaluation of the defect classification performance was made by comparing the accuracy, loss, and learning speed using verification data. The DenseNet-121 algorithm showed better performance than other algorithms with an accuracy of 99.13% and a loss value of 0.037. This was due to the structural characteristics of the DenseNet model, and the information loss was reduced by acquiring information from all previous layers for image identification in this algorithm. Based on the above results, the possibility of machine vision application of CNN-based model for the surface defect classification of Al extruded materials was also discussed.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3766-3777
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• 2022

It is essential to ensure the safety of spent nuclear fuel (SNF) transport cask in drop situation that is included in transport accident scenarios. The safety of the drop situation is affected by the impact absorption performance of impact limiters. Therefore, when designing an impact limiter, the uncertainty in the material properties that affect the impact absorption performance must be considered. In this study, the material properties of the wood inside the impact limiter were selected as the variables for a parametric study. The sensitivity analysis of the drop response of the SNF transport cask with impact limiter was performed. The minimum wood strength required to prevent a direct collision between the cask and floor was derived from the analysis results. In addition, the plastic strain response was analyzed and strain-based evaluation was performed. Based on this result, the critical values of wood properties that change the impact dynamic characteristics were investigated. Finally, the optimal material properties of wood were obtained to secure the structural safety of the SNF transport cask. The results of this study can contribute to the development of SNF transport cask, thereby ensuring safety in transport accident conditions.

• Journal of East Asia Management
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• v.2 no.1
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• pp.63-92
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• 2021

Human activities have been putting a great burden on the earth, leading to many serious problems, such as lack of resources, ecological degradation and air degradation. Although many countries have recognised this circumstance and have developed some sustainable development strategies, the earth still needs research on sustainability in different views and various industries. The nursing industry has grown with the ageing of the global population in recent years, and professional nursing institutions could relieve structural deterioration caused by the ageing population in family, social, economic and cultural. Hence, exploring the key criteria of organisational sustainability in the nursing industry is of the utmost priority. This paper puts forward an evaluation framework to identify the key criteria of organisational sustainability. After connections with nursing homes A and B in China, the author adopts literature research to confirm the criteria system which is based on triple bottom line, utilises analytical network process method to design the network hierarchy analysis model and importance comparison questionnaires to collect experts' first-hand data, and uses technical software - Super Decisions to integrate data and obtain final results. The results recommend three top-ranked criteria in the entire system, eco-recruitment, eco-procurement and corporate social responsibility are discussed with some professional suggestions in the end. The limitations are also extended in the last chapter to provide future research perspectives.

• Analyses & Alternatives
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• v.6 no.1
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• pp.223-258
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• 2022

The 2018 local elections completely upended the composition of Busan's city council, with the council membership changing from being solidly and consistently conservative to being over 80% liberal. What explains this anomalous outcome? While existing literature suggests the outcome of the 2018 city council elections was the consequence of a combination of structural and strategic factors, such as the decline of regional voting, we argue that the individual-level evaluation of President Moon Jae-in is one of the primary factors driving this result. Although coattails effects are commonly considered in concurrent national legislative elections, the Presidentialized and nationalized politics of Korea makes it possible for Presidential elections to affect local elections as well. We assess our explanation through an analysis of repeated cross-sectional survey data collected just before the 2018 local elections. The results of the analysis show that support for the Democratic Party is very strongly predicted by individual-level evaluation of President Moon. When considered in the context of the timing of presidential and local elections, the results suggest that Presidential coattail effects are capable of destabilizing established political patterns, such as regional voting, if perhaps only in a sporadic and idiosyncratic fashion, depending on whether or not local elections are held early on in a President's term.