• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.230-232
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• 2006

Failure behaviors of thin cylinder with corrosion are very important for the integrity of boiler and pressure vessel system. In this study, FEM with internal pressure are conducted on 1000 mm diameter (length 3000 mm and thickness, 5.9 mm) SS400 carbon steel. Failure behaviors of locally wall thinned cylinders were calculated by elasto-plastic analysis using finite element method. The elasto-plastic analysis was performed by FE code ANSYS. We simulated various types of local wall thinning that can be occurred at cylinder surface due to corrosion. Locally wall thinned shapes were machined to be different in size along the circumferential or axial direction of straight cylinder. In case of local wall thinned length 30 mm, internal pressure, when the crack initiation and the plastic collapse occur, didn't decrease dramatically even though local wall thinned depth was deep. In 400 mm, the more local wall thinned depth is deep, the more internal pressure decreased dramatically. In degraded materials, crack is easily initiation but plastic collapse was difficult.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.304-313
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• 2021

Nickel base Alloy X-750, which is used as fastener parts in light-water reactor (LWR), has experienced many failures by environmentally assisted cracking (EAC). In order to improve the reliability of passive components for nuclear power plants (NPP's), it is necessary to study the failure mechanism and to predict crack growth behavior by developing a probabilistic failure model. In this study, The Bayesian inference was employed to reduce the uncertainties contained in EAC modeling parameters that have been established from experiments with Alloy X-750. Corrosion fatigue crack growth rate model (FCGR) was developed by fitting into Paris' Law of measured data from the several fatigue tests conducted either in constant load or constant ΔK mode. These parameters characterizing the corrosion fatigue crack growth behavior of X-750 were successfully updated to reduce the uncertainty in the model by using the Bayesian inference method. It is demonstrated that probabilistic failure models for passive components can be developed by updating a laboratory model with field-inspection data, when crack growth rates (CGRs) are low and multiple inspections can be made prior to the component failure.

• Fashion & Textile Research Journal
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• v.24 no.2
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• pp.183-194
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• 2022

This study aims to understand the consumers' negative responses to communication failure of chatbots caused by their imperfections. Specifically, this study examines 1) the relationship among chatbot's communication failure, dissatisfaction, negative behavior (complaint, negative word-of-mouth (nWOM), and inertia); 2) the moderating effect of technostress on the relationship between chatbot's communication failure and dissatisfaction; 3) the differences in the negative responses between the generation MZ and the previous generations. Data were collected via an online survey. First, the participants interacted with the chatbot developed for this survey, to experience the chatbot's communication failure. Thereafter, they responded to a questionnaire. PLS-SEM was conducted using the R software environment to test the hypotheses. This study empirically identified that chatbot's communication failure positively affected dissatisfaction. In addition, the customers who were more dissatisfied with the chatbot's communication failures were more likely to complain than engage in nWOM. Compared to the generation MZ, chatbot's communication failure caused a higher level of dissatisfaction in previous generations. The results suggest that online shopping malls should carefully introduce an improved chatbot service after minimizing its communication failure rate. The chatbot developers of online shopping malls targeting middle-aged and elderly consumers should strive to develop and implement strategies to further alleviate consumers' dissatisfaction in the situation of chatbot's communication failure.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.95-102
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• 2008

COMS Satellite is automatically able to recover from any defined failure thanks to a full redundancy. This study assesses the effects of gyro failure on the COMS mission and analyzes the mechanism of Gyro Failure Detection, Isolation and Recovery about failure detection means, isolation and recovery actions and their consequences. At last, it checks the FDIR behavior from an injected failure on COMS simulator.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.79-82
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• 2002

A finite element method based on the two-dimensional progressive failure analysis considering material nonlinearity is presented for characterizing the strength and failure of the unidirectional-fabric hybrid laminated composite joints under pin loading. The 8-node laminated shell element is incorporated in the updated Lagrangian formulation. Failure criteria including the Maximum Stress and Tsai-Wu are used in conjunction with the complete unloading stiffness degradation method. For the verification, joint tests are conducted for the specimens with two different ply-number ratios of UD composite to fabric composite. Although there are some differences depending on ply-number ratios, the finite element model using the maximum stress criterion considering nonlinear material behavior predicts the failure strength best.

• Coupled systems mechanics
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• v.8 no.2
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• pp.111-127
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• 2019

In this paper, we present a 2D multi-scale coupling computation procedure for localized failure. When modeling the behavior of a structure by a multi-scale method, the macro-scale is used to describe the homogenized response of the structure, and the micro-scale to describe the details of the behavior on the smaller scale of the material where some inelastic mechanisms, like damage or plasticity, can be defined. The micro-scale mesh is defined for each multi-scale element in a way to fit entirely inside it. The two scales are coupled by imposing the constraint on the displacement field over their interface. An embedded discontinuity is implemented in the macro-scale element to capture the softening behavior happening on the micro-scale. The computation is performed using the operator split solution procedure on both scales.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.601-615
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• 2001

The study area. Boeun-eup Boeun-kun, belongs to Ogchon metamorphic belt which is highly metamorphosed and consisted of complex geologic formations. Even though the geological structures and formations are complex and metamorphosed, the geological investigation and consideration are not enough and consequently the plane failure is occurred in the rock slope which was under construction on 1 : 0.5 gradient. This area is assessed as unstable and additional failure is possible by the discontinuity with same direction of failure surface. Therefore, the authors evaluate the slope stability using various analysis methods such as SMR, stereographic projection method, and the limit equilibrium analysis. In order to analyze stress redistribution and nonlinear displacement behavior caused by stress release, the authors conduct numerical analysis with UDEC and then the behavior of rock mass is analyzed after reinforcements are applied.

• Geotechnical Engineering
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• v.4 no.3
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• pp.43-52
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• 1988

The behavior of clays subjected to Repeated loading has been shown to be very different from the behavior under a single load application. Especially the behavior of pore water pressure is Qf considerable importance. The objective of this work is to experimentally study the stress-strain characteristics of clays, and this study includes the pore water pressure which is built up during the load repetition. For this study, the samples were consolidated isotropically in the triaxial cell during 24 hours, .and monotonic strain controlled triaxial test is carried out by uslng the tests of Compression failure, Cycled at failure, and Nonfailure equilibrium on remoulded samples under undrained .condition . Consequently there exists a critical level of repeated loading which seperates the behavior of a particular sample into two distinctly different patterns.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.163-172
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• 2000

The postbuckling behavior and progressive damage of composite laminated cylindrical shell under uniform external pressure were investigated by nonlinear finite element method programming. For the finite element analysis, nine-node 3-D degenerated elements were utilized, and arc-length method including line search was adopted for the iteration and load-increment along postbuckling equilibrium path. As results. buckling load, postbucking behavior, and progressive failure f3r various composite laminated cylindrical shells were discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.165-175
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• 2006

To analyze the deformation and failure of slopes, generally, two types of model, Polynomial model and Growth model, are applied. These two models are focused on the behavior of the slope by time. Therefore, this research is more focused on predicting of slope failure than analyzing the slope behavior by time. Generally, Growth model is used to analyze the soil slope, to the contrary, Polynomial model is used for rock slope. However, 3-degree polynomial($y=ax^3+bx^2+cx+d$) is suggested to combine two models in this research. The main trait of this model is having an asymptote. The fields to adopt this model are Gosujae Danyang(soil slope) and Youngduk slope(rock slope), which are the cut-slope near national road. Data from Gosujae are shown the failure traits of soil slope, to the contrary, those of Youngduk slope are shown the traits of rock slope. From the real-time monitoring data of the slope, 3-degree polynomial is proved as excellent system to analyze the failure and behavior of slope. In case of Polynomial model, even if the order of polynomials is increased, the $R^2$ value and shape of the curve-fitted graph is almost the same.