• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.45-53
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• 2019

Thermal-hydraulic passive safety systems (PSSs) are incorporated into many advanced reactor designs on the bases of simplicity, economics and inherent safety nature. Several factors among which are the critical parameters (CPs) that influence failure and reliability of thermal-hydraulic (t-h) passive systems are now being explored. For simplicity, it is assumed in most reliability analyses that the CPs are independent whereas in practice this assumption is not always valid. There is need to critically examine the dependency influence of the CPs on reliability of the t-h passive systems at design stage and in operation to guarantee safety/better performance. In this paper, two multivariate analysis methods (covariance and conditional subjective probability density function) were presented and applied to a simple PSS. The methods followed a generalized procedure for evaluating t-h reliability based on dependency consideration. A passively water-cooled steam generator was used to demonstrate the dependency of the identified key CPs using the methods. The results obtained from the methods are in agreement and justified the need to consider the dependency of CPs in t-h reliability. For dependable t-h reliability, it is advisable to adopt all possible CPs and apply suitable multivariate method in dependency consideration of CPs among other factors.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1501-1507
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• 2006

The accidents are often resulted from multiple causes with hardware failure and human errors. So to ensure the safety of rail operation, human error should be prevented effectively. The purpose of this paper is to present an analysis system on factors of influencing human error in korean rail industry especially for engine driver and train despatcher. To achieve it, ESFs(error shaping factors) classification system was derived from several PSFs(performance shaping factors) classification system. Based on them, two kinds of questionnaires for engine driver and train despatcher each were developed. Then Analytic Hierarchy Process (AHP) methodology was used to evaluate what factors were critical to human error.

• Journal of Global Scholars of Marketing Science
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• v.15 no.2
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• pp.123-140
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• 2005

Recently, one of the issues that are significantly considered is to keep Changwon F3 car racing. In most existing studies, however, there is shortage of opinions for understanding the reactions of the host community. The question addressed in this paper is what are the underlying factors that affect which inhibitors are likely to be discussed by the host community for car racing. Survey collected from 299 participants in Changwon city were analyzed to test their reactions. Through the empirical study, several research findings emerged. The results indicate that (1) the event seeker, the drive seeker, and the hard internal seeker were significant discriminant factors to separate inhibitors from the host community, (2) the significant differences between the recognition of demographic characteristics and that of negative effects, (3) the significant level between cluster groups(overcontrolled, resilient, undercontrolled) and negative effects is found. The findings also provide implications for practice on several fronts, which is to understand the reaction of the host community to F3 car racing, and for the event planner to reduce complaints.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.600-612
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• 2009

Special banks primarily using Internet have different properties in transactions with customers, risk management, capital strength, and branch networks with general banks. The success and failure factors of Internet banks have been explained only by the economies of scale, and learning and experience effects of Internet banks based on the perspective of organizational ecologies. In this study, the success factors of Internet banks are investigated based on strategic choice by organizations and resource-based view of the firms instead of organizational ecology perspective. To this end, 31 major Internet banks operating in overseas market have been classified by the size and profitability of banks, and three strategic groups have been derived. three representative company cases were analyzed. critical success factors of Internet banks were derived, and considerable points when operating Internet banks were discussed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.4
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• pp.71-80
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• 1990

Model tests for the ultimate pullout resistance of anchorages and investigation of failure behaviors in cohesionless soil have been conducted. The factors affecting the anchorage are mostly the geometry of the system, and soil properties of sands. The main conclusions of the experimental work were as follows. 1. The load - displacement relationship can be a form of parabolic curve for all plates. 2. The change in ultimate pullout resistance of anchor is mostly affected by embedment ratio and size of anchor, and influenced to a lesser degree by its shape. 3. Critical embedment ratio which is defined as the failure mode changes from shallow to deep mode is increased with increasing height of anchor. 4. For a constant anchor height, as the width of anchor increases the ultimate pullout resistance also increases. However, considering the efficiency of anchor for unit area, width of anchor does not appear to have any sigrnificant contribution on increasing anchor city. 5. Anchor capacity has a linear relation to sand density for any given section and the rate of change increases as the section increases. Critical depth determining the failure patterns of anchor is decreased with a decrease of sand density. 6. With increasing inclination angle, size of anchor, and decreasing embedment ratio, the ultimate pullout resistance of anchor under inclined loading is significantly decreased. 7. The ultimate pullout resistance of double anchor, a method of improving single of anchor capacity, is influenced by the center - to - center spacing adjacent anchors. It is also found that tandem and parallel anchor rigging arrangements decrease the anchor system capacity to less than twice the single anchor capacity due to anchor interference.

• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.177-190
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• 2006

Construction projects are facing delay problems. Delays in construction have been immense effect on performance or satisfactory delivery of the project. Delays have been causing project cost overrun as well as it is a source of dispute hence damaging the relationship between the project participants. The purpose of this study was to explore the causes of delay risk through a field survey study. Data were collected from construction professionals working in owner, consultant and contractor organizations. All together 208 questionnaire instruments were used and analyzed by employing statistical tools (SPSS computer program). 19 delay factors were identified by this study, out of which following factors were critical: Frequent interruptions from public (local people, pressure group etc.), changed site condition, failure to provide required construction site, unrealistic project time estimation and design errors.

• Steel and Composite Structures
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• v.29 no.4
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• pp.437-450
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• 2018

A bridge comprising of two girders, such as a twin steel box-girder bridge, is classified as fracture critical (i.e., non-redundant). In this study, the various bridge components of the twin steel box-girder bridge are investigated to determine if these could be utilized to improve bridge redundancy. Detailed finite-element (FE) models, capable of simulating prominent failure modes observed in a full-scale bridge fracture test, are utilized to evaluate the contributions of the bridge components on the ultimate behavior and redundancy of the bridge sustaining a fracture on one of its girders. The FE models incorporate material nonlinearities of the steel and concrete members, and are capable of capturing the effects of the stud connection failure and railing contact. Analysis results show that the increased tensile strength of the stud connection and (or) concrete strength are effective in improving bridge redundancy. By modulating these factors, redundancy could be significantly enhanced to the extent that the bridge may be excluded from its fracture critical designation.

• Steel and Composite Structures
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• v.47 no.2
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• pp.269-287
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• 2023

The WGJ420 fire-resistant weathering (FRW) steel is developed and manufactured with standard yield strength of 420 MPa at room temperature, which is expected to significantly enhance the performance of steel structures with excellent fire and corrosion resistances, strong seismic capacity, high strength and ductility, good resilience and robustness. In this paper, the mechanical properties of FRW steel plates and buckling behavior of columns are investigated through tests at elevated temperatures. The stress-strain curves, mechanical properties of FRW steel such as modulus of elasticity, proof strength, tensile strength, as well as corresponding reduction factors are obtained and discussed. The recommended constitutive model based on the Ramberg-Osgood relationship, as well as the relevant formulas for mechanical properties are proposed, which provide fundamental mechanical parameters and references. A total of 12 FRW steel welded I-section columns with different slenderness ratios and buckling load ratios are tested under standard fire to understand the global buckling behavior in-depth. The influences of boundary conditions on the buckling failure modes as well as the critical temperatures are also investigated. In addition, the temperature distributions at different sections/locations of the columns are obtained. It is found that the buckling deformation curve can be divided into four stages: initial expansion stage, stable stage, compression stage and failure stage. The fire test results concluded that the residual buckling capacities of FRW steel columns are substantially higher than the conventional steel columns at elevated temperatures. Furthermore, the numerical results show good agreement with the fire test results in terms of the critical temperature and maximum axial elongation. Finally, the critical temperatures between the numerical results and various code/standard curves (GB 51249, Eurocode 3, AS 4100, BS 5950 and AISC) are compared and verified both in the buckling resistance domain and in the temperature domain. It is demonstrated that the FRW steel columns have sufficient safety redundancy for fire resistance when they are designed according to current codes or standards.

• Journal of the Korean Professional Engineers Association
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• v.41 no.2
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• pp.64-67
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• 2008

According to grow maritime activities in coastal zone, a threat increase to the marine environment from oil spill. The success or failure of initial effort depends on the adequacy of the plan and the ability of immediate execution. Successful response to oil spills requires critical information in real time topics, including spill data, environmental conditions, ecological factors. Diverse simulation provides tactical decision-makers with the information on the movement of pollutant.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.81-88
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• 2013

In Korean society, the theme of human errors in railway has been emerging as a critical issue. As far as human error studies are concerned, main trend has been inclined to be led by industrial engineering and systems science. Apart from those trends, this study empirically highlighted the relationship between depression, which has been a frequent research subject in the medical science and psychology, and accidents, with setting depression as an exogenous variable and cognitive failure and mistake as endogenous variables, respectively. Results of hypotheses test for the 204 respondents showed that driver's depression has a significant effect on accidents mediated by cognitive failure and mistake. This findings suggest the need for exploring the diverse latent factors causing human errors and for understanding the complex cognitive process as well as for establishing integrative countermeasures to mitigate human errors.