• Computers and Concrete
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• v.15 no.4
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• pp.589-606
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• 2015

It is well-documented that the major deterioration of coastal RC structures is chloride-induced corrosion. Therefore, regional investigations are necessary for durability based design and evaluation of the proposed service life prdiction models. In this paper, four reinforced concrete jetties exposed to severe marine environment were monitored to assess the long term chloride penetration at 6 months to 96 months. Also, some accelerated durability tests were performed on standard samples in laboratory. As a result, two time-dependent equations are proposed for basic parameters of chloride diffusion into concrete and then the corrosion initiation time is estimated by a developed probabilistic service life model Also, two famous service life prediction models are compared using chloride profiles obtained from structures after about 40 years in the tidal exposure conditions. The results confirm that the influence of concrete quality on diffusion coefficients is related to the concrete pore structure and the time dependence is due to chemical reactions of sea water ions with hydration products which lead a reduction in pore structure. Also, proper attention to the durability properties of concrete may extend the service life of marine structures greater than fifty years, even in harsh environments.

• International Journal of Concrete Structures and Materials
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• v.9 no.4
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• pp.487-498
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• 2015

A proper initial curing is a very simple and inexpensive alternative to improve concrete cover quality and accordingly extend the service life of reinforced concrete structures exposed to aggressive species. A current study investigates the effect of wet curing duration on chloride penetration in plain and blended cement concretes which subjected to tidal exposure condition in south of Iran for 5 years. The results show that wet curing extension preserves concrete against high rate of chloride penetration at early ages and decreases the difference between initial and long-term diffusion coefficients due to improvement of concrete cover quality. But, as the length of exposure period to marine environment increased the effects of initial wet curing became less pronounced. Furthermore, a relationship is developed between wet curing time and diffusion coefficient at early ages and the effect of curing length on time-to-corrosion initiation of concrete is addressed.

• Smart Structures and Systems
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• v.18 no.3
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• pp.569-584
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• 2016

This paper presents a method for stochastic modelling of fatigue crack growth and optimising inspection and maintenance strategy for the structural members of steel bridges. The fatigue crack evolution is considered as a stochastic process with uncertainties, and the Gamma process is adopted to simulate the propagation of fatigue crack in steel bridge members. From the stochastic modelling for fatigue crack growth, the probability of failure caused by fatigue is predicted over the service life of steel bridge members. The remaining fatigue life of steel bridge members is determined by comparing the fatigue crack length with its predetermined threshold. Furthermore, the probability of detection is adopted to consider the uncertainties in detecting fatigue crack by using existing damage detection techniques. A multi-objective optimisation problem is proposed and solved by a genetic algorithm to determine the optimised inspection and maintenance strategy for the fatigue affected steel bridge members. The optimised strategy is achieved by minimizing the life-cycle cost, including the inspection, maintenance and failure costs, and maximizing the service life after necessary intervention. The number of intervention during the service life is also taken into account to investigate the relationship between the service life and the cost for maintenance. The results from numerical examples show that the proposed method can provide a useful approach for cost-effective inspection and maintenance strategy for fatigue affected steel bridges.

• Journal of Korean Society for Quality Management
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• v.51 no.1
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• pp.67-78
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• 2023

Purpose: The purpose of this study is to investigate the COVID-19 pandemic-driven effect changes of quality factors on customer satisfaction in Korean Police Civil Affairs Service. Methods: This study fitted a regression model to the data collected by Korean National Police Agency from 2019 (before COVID-19 pandemic) to 2020 (during COVID-19 pandemic). In order to simultaneously estimate the effects of major seven quality factors on customer satisfaction for 'before the pandemic' and for 'during the pandemic', the regression model included not only customer satisfaction as the dependent variable, but also the fourteen independent variables consisting of the seven quality factors and their seven interaction terms. The interaction terms were defined by multiplying each quality factor by a dummy variable indicating either before or during the pandemic. Therefore, the coefficient estimates of the interaction terms indicate the changes of their corresponding quality factor effects on customer satisfaction between before and during the pandemic. The double bootstrap method was applied to test the significance of coefficient estimates. Results: Both before and during the pandemic, all quality factors had positive effects on customer satisfaction. However, these effects changed differently from before to during the pandemic: (increased) supportability, sincerity, and convenience; (decreased) integrity, professionalism, and fairness; (unchanged) promptness. Conclusion: This study found that the pandemic caused significant effect changes of quality factors on customer satisfaction in Korean Police Civil Affairs Service. This finding suggests the necessity of carefully monitoring such effect changes to effectively and efficiently improve customer satisfaction. This study also identified that from before to during the pandemic, supportability, sincerity, and convenience become more important and hence, need to be better managed.

• International Journal of Computer Science & Network Security
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• v.22 no.10
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• pp.155-164
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• 2022

The review of known decisions showed that currently there are no systems and technologies for supporting the decision about the possibility of concluding the civil law agreements for medical, therapeutic and dental services. The paper models the decision-making support process on the possibility of concluding the civil law agreements for medical, therapeutic and dental services, which is the theoretical basis for the development of rules, methods and system for supporting the decision about the possibility of concluding the civil law agreements for medical, therapeutic and dental services. The paper also developed the system for supporting the decision about the possibility of concluding the civil law agreements for medical, therapeutic and dental services, which automatically and free determines the possibility or impossibility of concluding the corresponding civil law agreement for the provision of a corresponding medical service. In the case of formation of a conclusion about the possibility of concluding the agreement, further conclusion and signing of the corresponding agreement takes place. In the case of forming a conclusion about the impossibility of concluding the agreement, a request is made for finalizing the relevant agreement for the provision of the relevant medical service, indicating the reasons for the impossibility of concluding the agreement - missing essential conditions in the agreement. After finalization, the agreement can be analyzed again by the developed system for supporting the decision.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.8-17
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• 2017

Infrastructures such as bridges and tunnels are crucial elements of national economic growth, and sudden collapses may lead to great catastrophes with significant social and economic losses, as well as a loss of lives. Hence, an efficient maintenance technique must be applied to guarantee safety, secure budgets to maintain a certain level of service, and prevent maintenance expenditures from being concentrated in a specific time period. Developed countries have experienced rapid increases in maintenance budgets, and maintenance costs now account for about 40% of the total maintenance budget. The level of service in asset management systems is an essential element for setting management goals and making priority decisions. Therefore, this study uses fuzzy theory to develop a new way to assess the level of service.The assessment model was applied to an actual bridge to evaluate the level of service for users.

• Korean Security Journal
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• no.10
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• pp.35-52
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• 2005

This study is focused on the service quality and customer satisfaction. The survey on the service quality and customer satisfaction has the follows; First, man group compared to female group provision was receiving the service of good quality and also the customer satisfactory degree appeared highly. Also, the quality of the group one recording service where the age is many appeared customer satisfactory boat song highly. Second, the customer satisfaction regarding a high educational background one recording service quality did not appear highly and not to be with the thing recording where the educational background will be high provision to receive a more many serviceit is satisfied it appeared. It follows, consequently in member of society nine statistics quality and service quality of civil expense and the customer satisfaction is a difference and the recording customer where the service quality of civil expense will be high it goes round satisfactorily and there is possibility of saying that. Third, in service quality empathy characteristic of subordinate result, with the fact that static effect it will be going mad to a shedding of corporeal service satisfaction and a security facility satisfaction. The security facility satisfaction where the empathy characteristic and shedding of corporeal service quality will be good is high reflects a fact and it is giving. Fourth, market segment anger strategy and there is a necessity which will form the customer layer which is various. Also, the site for the service of good quality the operation of development and strategy elder brother system of the elder brother system which it fixes is necessary.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.321-328
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• 2014

Clear understanding and related information management of geography and city facilities are the fundamental approach to prevent city disaster. In order to accomplish the service to prevent city disaster effectively, there needs to be a consistent framework for data collection, to build models, and to manage information. In this study, the authors proposed standardized city information modeling process and application concept to use information model for service of preventing city disaster in information management standpoint. The study was conducted on the process of classification and necessary attributes to manage city facilities effectively considering disaster related information. Additionally, the study suggested the methods for building an open city information model based on an integrated data schema, CityGML. Finally, through the implementation of sample model, the study confirmed city information modeling methodology and applicability for service of disaster prevention.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.754-768
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• 2022

Purpose: The purpose of this study is to derive improvements through user satisfaction analysis for the smart traffic safety system being applied to improve traffic safety. Method: A survey-based IPA analysis was used to derive system and service improvements for groups of drivers and pedestrians. Result: As a result of the analysis, both drivers and pedestrian groups showed that Quadrant 1(Keep up the Good Work) was 'Perception of risk information', and Quadrant 3(Low Priority) was 'Reliability of warning information'. On the other hand, 'AI display suitability', which was analyzed as Quadrant 1(Keep up the Good Work) in the driver group, was found to be Quadrant 3(Low priority) in the pedestrian group. Conclusion: Satisfaction factors for smart pedestrian safety systems may vary depending on users, and it is judged that user-centered system construction and service provision are necessary.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.553-561
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• 2010

Like the shotcrete can be deteriorated by chemical compounds as service years increase, the grout which is used to fasten the cablebolt(rockbolt) system in the underground structures also can be deteriorated by chemical compounds such as sulphate and/or chloride contained in groundwater during service years. This can induce issues on the long term durability of cablebolt(rockbolt) system and consequently on the stability of underground structures. In this study, the deteriorations of long term durability of cement mortar grout by each chemical compound of sulphate or chloride are studied experimentally and also complex deterioration by the mix of sulphate and chloride is investigated. Based on the results obtained in this study, the characteristics and prediction of deterioration of long term durability of cement mortar grout for cablebolt(rockbolt) system are suggested.