• Steel and Composite Structures
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• v.19 no.1
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• pp.59-74
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• 2015

Since there are several places located in active seismic zones in the world, serious damages and losses have happened due to major scaled earthquakes. Especially, structures having different irregularities have been severely damaged or collapsed during these seismic events. Behavior of existing structures under several loading conditions is not completely determined due to some uncertainties. This situation reveals the importance of design and analysis of structures under seismic effects. Several non-linear static procedures have been developed in recent years. Determination of the seismic safety of the existing structures and strengthening techniques are significant civil engineering problems Non-linear methods are defined in codes to determine the performance levels of structures more accurately. However, displacement based ones give more realistic results. These methods provide more reliable evaluation possibilities for existing structures with developing computer technology. In this study, non-linear performance analysis of existing and strengthened steel structures by X shaped bracing members with 3, 5 and 7 stories which have soft story irregularity is performed according to FEMA-356 and Turkish Earthquake Code-2007. Damage ratios of the structural members and global performance levels are determined as well as modal properties and story drift ratios after non-linear finite elements analysis for each structure.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1513-1523
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• 2017

Improvement of numerical analysis methods has been required to solve complicated phenomena that occur in nuclear facilities. Particularly, fluid-structure interaction (FSI) behavior should be resolved for accurate design and evaluation of complex reactor vessel internals (RVIs) submerged in coolant. In this study, the FSI effect on dynamic characteristics of RVIs in a typical 1,000 MWe nuclear power plant was investigated. Modal analyses of an integrated assembly were conducted by employing the fluid-structure (F-S) model as well as the traditional added-mass model. Subsequently, structural analyses were carried out using design response spectra combined with modal analysis data. Analysis results from the F-S model led to reductions of both frequency and Tresca stress compared to those values obtained using the added-mass model. Validation of the analysis method with the FSI model was also performed, from which the interface between the upper guide structure plate and the core shroud assembly lug was defined as the critical location of the typical RVIs, while all the relevant stress intensities satisfied the acceptance criteria.

• Smart Structures and Systems
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• v.14 no.6
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• pp.1221-1245
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• 2014

Real-time hybrid simulation (RTHS) is a promising cyber-physical technique used in the experimental evaluation of civil infrastructure systems subject to dynamic loading. In RTHS, the response of a structural system is simulated by partitioning it into physical and numerical substructures, and coupling at the interface is achieved by enforcing equilibrium and compatibility in real-time. The choice of partitioning parameters will influence the overall success of the experiment. In addition, due to the dynamics of the transfer system, communication and computation delays, the feedback force signals are dependent on the system state subject to delay. Thus, the transfer system dynamics must be accommodated by appropriate actuator controllers. In light of this, guidelines should be established to facilitate successful RTHS and clearly specify: (i) the minimum requirements of the transfer system control, (ii) the minimum required sampling frequency, and (iii) the most effective ways to stabilize an unstable simulation due to the limitations of the available transfer system. The objective of this paper is to establish a stability switch criterion due to systematic experimental errors. The RTHS stability switch criterion will provide a basis for the partitioning and design of successful RTHS.

• Journal of Korean Academy of Nursing
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• v.45 no.6
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• pp.802-811
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• 2015

Purpose: The purpose of this study was to test and validate a model to predict living and brain death organ donation intention in nursing students. The conceptual model was based on the theory planned behavior. Methods: Quota sampling methodology was used to recruit 921 nursing students from all over the country and data collection was done from October 1 to December 20, 2013. Results: The model fit indices for the hypothetical model were suitable for the recommended level. Knowledge, attitude, subjective norm and perceived behavioral control explained 40.2% and 40.1% respectively for both living and brain death organ donation intention. Subjective norm was the most direct influential factor for organ donation intention. Knowledge had significant direct effect on attitude and indirect effect on subjective norm and perceived behavioral control. These effects were higher in brain death organ donation intention than in living donation intention. Conclusion: The overall findings of this study suggest the need to develop systematic education programs to increases knowledge about brain death organ donation. The development, application, and evaluation of intervention programs are required to improve subjective norm.

• Smart Structures and Systems
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• v.16 no.4
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• pp.683-699
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• 2015

Time Domain Reflectometry (TDR) has been extensively applied for various laboratory and field studies. Numerous different TDR probes are currently available for measuring soil moisture content and detecting interfaces (i.e., due to landslides or structural failure). This paper describes the development of an innovative spiral-shaped TDR probe that features much higher sensitivity and resolution in detecting interfaces than existing ones. Finite element method (FEM) simulations were conducted to assist the optimization of sensor design. The influence of factors such as wire interval spacing and wire diameter on the sensitivity of the spiral TDR probe were analyzed. A spiral TDR probe was fabricated based on the results of computer-assisted design. A laboratory experimental program was implemented to evaluate its performance. The results show that the spiral TDR sensor featured excellent performance in accurately detecting thin water level variations with high resolution, to the thickness as small as 0.06 cm. Compared with conventional straight TDR probe, the spiral TDR probe has 8 times the resolution in detecting the water level changes. It also achieved 3 times the sensitivity of straight TDR probe.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.177-195
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• 2016

To secure the stability of geotechnical infrastructures and minimize failures during the construction process, a number of support systems have been introduced in the last several decades. In particular, stabilization methods using steel bars have been widely used in the field of geotechnical engineering. Rock bolt system is representative support system using steel bars. Pre-stressing has been applied to enhance reinforcement performance but can be released because of the failure of head or anchor sections. To overcome this deficiency, this paper proposes an innovative support system that can actively reinforce the weak ground along the whole structural element by introducing an active tension bolt containing a spring unit to the middle of the steel bar to increase its reinforcement capacity. In addition, the paper presents the support mechanism of the active tension bolt based on a theoretical study and employs an experimental study to validate the performance of the proposed active tension bolt based on a down-scaled model. To examine the feasibility of the active tension unit in a pillar, the paper considers a pullout test and a small-scale experimental model. The experimental results suggest the active tension bolt to be an effective support system for pillar reinforcement.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.3
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• pp.283-293
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• 2019

The purposes of the study are threefold: (1) develop key successful factors of blockchain platform for micro-enterprises based on Balanced Scorecard (BSC), (2) find out the correlation between the key successful factors of blockchain platform for micro-enterprises, and (3) understand the perception of micro-enterprise blockchain and the difference between theoretical guidance and practical application. This study combines Interpretative Structural Modeling Method, (ISM) and Decision-Making Trial and Evaluation Laboratory (DEMATEL) to analyze the causal relationships and hierarchical structures of the 12 key successful factors of blockchain platform for micro-enterprises and understand the correlation between factors. The 12 key successful factors developed based on the four perspectives of the Balanced Scorecard, and the questionnaire designs based on the concept of DEMATEL, and then analyzed data by DEMATEL and ISM methods to understand the correlation between key factors. The research results show that the key successful factors of blockchain platform for micro-enterprises include "brand equity", "security and anti-counterfeiting", "sales growth", "transparency and clear", "trust", "consensus mechanism", "traceability", "consistency", "tracking", "innovation management", "international", "organizational adaptation", in which consumer "trust" plays an important role. Micro-enterprises can use blockchain to expand the market, provide customers with better service quality, and bring sales growth to micro-enterprises.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.100-105
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• 2008

A106 Carbon Steel has recently been used as the material for pipes, nozzles, and tank shells in nuclear power plants. Its corrosion resistance gives the steel many advantages for use in structures under high temperature and high pressure. This steel is also expected to be used as a structural material in the shipbuilding industry for applications involving severe conditions, such as high temperature and pressure. In this study, the mechanical properties of A106 carbon steel were evaluated in regard to its corrosion times. The tensile and yielding strengths decreased as the corrosion time increased. In particular, the tensile strength was influenced by corrosion. In addition, an acoustic emission (AE) technique was used to clarify the microscopic damage to specimens that had undergone corrosion for a certain period. It was found that AE parameters, such as events, energy, duration time, and amplitude were useful for evaluating the degree of damage and remaining life of the corroded specimen. Various properties of the waveform and frequency range were also seen, based on the degree of damage to the specimen from the corrosion time.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.58-64
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• 2008

In order to identify the exact behavior of corbel section, the horizontal force acting on corbel section should be considered as well as the vertical force. In this study, a new corbel section, which is economical and easy to construct, is developed by evaluating the exact strength of the section. Experiments were performed to verify the strengths of the proposed sections comparing with those of the currently used section. The summary of the experiment results are as follows: 1) In order to minimize the horizontal force effect, it was found that the use of pre-stressing was most effective, and that TB type corbel section is a most efficient section in terms of economy and workability. 2) The experimentally obtained strength of corbel section matched well with that estimated using shear friction theory. Therefore, it is concluded that shear friction theory would be very useful if a precise crack angie in the corbel section, which is pre-stressed by PS strings and threaded bolts, is available.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.433-438
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• 1998

Design lateral strength calculated by current seismic design code is prescribed to be much lower than the force level required for a structure to respond elastically during design level earthquake ground motion. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factor known as "response modification factor, R". This factor accounts for the inherent ductility, overstrength, redundancy, and damping of a structural system. This study considers ductility and overstrength of the wall-type structure for investigating R factor. This means that R factor is determined from the product of "ductility-based R factor($R_$\mu$$) and overstrength factor($R_s$). $R_$\mu$$ factor is calibrated to attain the targer ductility ratio (system ductility capacity) and produced in the from of $R_$\mu$$ spectra considering the influence of target ductility, natural period, and hysteretic model. On the other hand, $R_s$ is more difficult to quantify, since it depends on both material and system-dependent uncertain parameters. In this study Rs factor was determined from the result of push-over analysis.-over analysis.