• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.603-608
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• 2011

In recent years, numerous mega-sized and complex civil infrastructures are being constructed all over the world. Therefore, more precise construction and maintenance technologies are required for these complicated construction projects. Especially, exact strength measurement and curing process monitoring of the concrete structures are very crucial to confirm the safety and effectiveness of these complicated structures. In this paper, a new Quick Response (QR) code-based concrete strength labeling technique using embedded self-sensing monitoring system is introduced. It is important to note that the QR code-based concrete labeling technique enables easy access of the databases related to the concrete strength at anytime, anywhere, and any smart PC devices. Finally, by integrating the proposed QR code-based concrete labeling with the concrete strength databases already prepared at a designated web-server, a feasibility of the current system is investigated for a next generation concrete life-cycle quality maintenance.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.37-42
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• 2020

In the field of public informatization maintenance business, the attacks of external illegal users such as unauthorized leakage, destruction, and alteration due to intentional or inadequate management of personal information are increasing. In order to prevent such security incidents in advance, it is necessary to develop and quantitatively manage SLA indicators. This study presents the privacy SLA indicators and suggests specific methods such as information collection method and timing of the privacy SLA indicators. In order to confirm the validity and reliability of the proposed SLA indicators, an online survey was conducted with a group of experts. As a result, it was evaluated that compliance rate of personal information destruction and compliance rate of personal information protection system would be effective when applied to new and revised SLA indicators in terms of importance and validity. In the future, using SLA indicators for personal information protection as a standard for public information maintenance will contribute to improving SW quality and securing safety.

• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.791-798
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• 2014

Wu and Clements-Croome (2005) suggest the preventive maintenance (PM) model with random maintenance quality. They assume that each PM resets the failure rate to zero and the rate of increases of the failure rate gets higher after each additional PM. However a system may not be restored to as good as new immediately after the completion of PM. Thus, this paper modifies the Wu and Clements-Croome's PM model and then the optimal PM policy is suggested. To determine the optimal PM policy, we utilize the expected cost rate per unit time for our model. That is, we obtain the optimal number and the optimal period by minimizing the expected cost rate per unit time. The numerical examples are presented for illustrative purpose.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.122-129
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• 2013

Since electrical resistivity of concrete can be measured in a more rapid and simple way than chloride diffusivity, it should be primarily regular quality control of the electrical resistivity of concrete which provides the basis for indirect of quality control of chloride diffusivity during concrete construction. If this is realized, the electrical resistivity of concrete can be a crucial parameter to establish maintenance strategy for marine concrete structures. The purpose of this study is to develop, design and test a surface electrical resistivity measurement protocol. Microstructural affecting factors such as capillary water, porosity, tourtousity, and so on, on the electrical resistivity of concrete were examined taking into account for mixing proportion properties, and hydration stage. This study can provide a non-destructive approach for durability design of marine concrete. From the relationship between electrical resistivity and chloride diffusivity, it is expected that the result is subsequently used as a calibration curve for an indirect control of the chloride diffusivity based on regular measurements of the electrical resistivity during concrete construction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.105-113
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• 2012

Maintenance training is generally provided to teach employees new knowledge and techniques in order to increase their qualities. It means that the purpose of maintenance training is to increase an employee's knowledge or technique level and to maintain or increase their performance level through continuous training in their field, and the methods, contents and the level of training vary depending on the type of job they perform. Maintenance training is more important for jobs that require continuous technical increases or research, or for professional jobs that continuously require new knowledge and techniques. The purpose of this study is to provide quality service to consumers by responding to the rapidly changing jewelry distribution environment and to quickly and accurately acquire new and advanced jewelry inspection and appraisal techniques, and to contribute to the healthy consumption culture through a general quality increase in the jewelry industry.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.39-49
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• 2021

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force's de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.203-214
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• 2021

This study aimed at establishing a packaging standardization method that allows the maintenance of biological control agents product quality during delivery. First, based on the results of distribution status analysis of biological control agent products from four manufacturers, we confirmed that the mean temperature was maintained at 25.6℃ (minimum and maximum temperatures.: 18.1 and 30.7℃, respectively) inside the packaging box of each company for 36-48 h. To establish the optimal packaging method for each season, seven external temperature conditions were set ranging between 0℃ and 30℃ at intervals of 5℃. In addition, we evaluated internal temperature maintenance performance for each coolant pack handling method and determined 14 packaging combinations. A packaging combination that maintained a temperature of 3℃ - 9.9℃ at each external temperature conditions was considered efficient. This temperature range is close to a lower developmental threshold at which the biological control agents can survive with minimum energy for 12 h (direct delivery time), or 36-48 h (general delivery time) after packaging.

• Journal of People, Plants, and Environment
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• v.23 no.3
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• pp.347-362
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• 2020

Background and objective: It is difficult to conclusively determine the exact cause of tree defects since multiple causes are involved such as climate change, plantation, tree quality and planting time, construction, planting base, drainage, sunshine conditions, maintenance, and microclimate. The data related to landscaping construction defects are scattered or fragmented by companies and years, but not managed systematically by the defect information management system. Most of the earlier studies associated with tree defects in apartment complexes suggested defect rates after examining tree defects in the completed construction site and proposed fragmentary and subjective conclusions about the causes of defects observed in trees with high defect rates. It is proposed to continue to conduct studies on the establishment and analysis of systematic databases to identify the exact causes of tree defects and measures to improve, and the need to accumulate systematic data in the construction process where many defects arises. This study was conducted to reduce the defects of trees planted in apartment complexes. Methods: Main factors related to tree defects were subdivided based on the results of literature review and a defect investigation at the completion site, and tree history management items were selected and subdivided during the construction stage. Results: The criteria for the preparation of subdivided items were obtained, and the tree history management checklist was written for the site under actual construction and a systematic database was established. Items that are categorized based to the causes of defects include the location of nurseries, date, tree quality, site conditions, planting techniques, microclimates, and maintenance. Conclusion: This study suggested tree history management items based on the tree defects that can be identified at the construction stage and applied them to the selected study site, which differentiates this study from earlier studies. It will be necessary to conduct a comprehensive and objective time series analysis on tree defects that occur over time by continuously monitoring and collecting data after construction.

• Journal of Distribution Research
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• v.10 no.2
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• pp.99-120
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• 2005

First, based on extant studies in the field, the author extracts environments, general and personalized interactions between an internet shopping mall and its customers, interactions among customers, and outcomes as 5 relevant dimensions of the service quality of an internet shopping mal She derives hypotheses on the relationships between each of the service quality dimensions and each of the three components of the relationship quality, satisfaction, trust, and commitment. She also investigates the moderating role of the relationship duration defined by the length of use in the relationships. She studies the relationships among the three relationship quality components and their effects on the future intentions of relationship maintenance, too. Through a survey on college students and adult consumers, she gathers 349 qualified questionnaires. Applying regression methods on the data, she finds out that most of the relationships between each of the service quality dimensions and each of the relationship quality dimensions are statistically significant but that the strengths of relationship are quite different dimension by dimension. The moderating effect of the relationship duration is not found except one case, the relationship between general interactions and trust. The author also finds out positive relationships between satisfaction and trust between satisfaction and commitment, and between trust and commitment. Positive relationships between trust and the future intention of relationship maintenance and between commitment and the future intention are found. But the data does not reveal any statistically significant relationship beetween satisfaction and the future intention. The author provides a few implications of the research results and future research agenda.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.35-44
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• 2018

PURPOSES : The purpose of this research is to analyze the characteristics of panels that affect the evaluating results of riding quality and to evaluate the appropriateness of roughness management criteria based on ride comfort satisfaction. METHODS : In order to analyze the influence of panel characteristics of riding quality, 33 panels, consisting of civilians and experts, were selected. Also, considering the roughness distribution of the expressway, 35 sections with MRI ranging from 1.17 m/km to 4.65 m/km were selected. Each panel boarded a passenger car and evaluated the riding quality with grades from 0 to 10, and assessed whether it was satisfied or not. After removing outlier results using a box plot technique, 964 results were analyzed. An ANOVA was conducted to evaluate the effects of panel expertise, age, driving experience, vehicle ownership, and gender on the evaluation results. In addition, by using the receiver operating characteristics (ROC) curve, the MRI value, which can most accurately evaluate the satisfaction with riding quality, was derived. Then, the compatibility of MRI was evaluated using AUC as a criterion to assess whether the riding quality was satisfactory. RESULTS : Only the age of the panel participants were found to have an effect on the riding quality satisfaction. It was found that satisfaction with riding quality and MRI are strongly correlated. The satisfaction rate of roughness management criteria on new (MRI 1.6 m/km) and maintenance (MRI 3.0 m/km) expressways were 95% and 53%, respectively. As a result of evaluating the roughness management criteria by using the ROC curve, it was found that the accuracy of satisfaction was the highest at MRI 3.1-3.2 m/km. In addition, the AUC of the MRI was about 0.8, indicating that the MRI was an appropriate index for evaluating the riding quality satisfaction. CONCLUSIONS : Based on the results, the distribution of the panels' age should be considered when panel rating is conducted. From the results of the ROC curve, MRI of 3.0 m/km, which is a criterion of roughness management on maintenance expressways, is considered as appropriate.