• Elastomers and Composites
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• v.55 no.2
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• pp.81-87
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• 2020

Service life prediction and evaluation of rubber components is the foundational technology necessary for securing the safety and reliability of the product and to ensure an optimum design. Even though the domestic industry has recognized the importance thereof, technology for a systematic design and analysis of the same has not yet been established. In order to develop this technology, identifying the fatigue damage parameters that affect service life is imperative. Most anti-vibration rubber components had been damaged by repeated load and aging. Hence, the evaluation of the fatigue characteristics is indispensable. Therefore, in this paper, we propose a method that can predict the service life of rubber components relatively accurately in a short period of time. This method works even in the initial designing stage. We followed the service life prediction procedure of the proposed rubber components. The weak part of the rubber and the maximum strain were analyzed using finite element analysis of the rubber bushing for the tracked vehicles. In order to predict the service life of the rubber components that were in storage for a certain period of time, the fatigue test was performed on the three-dimensional dumbbell specimen, based on the results obtained by the rubber material acceleration test. The service life formula of the rubber bushing for tracked vehicles was derived using both finite element analysis and the fatigue test. The service life of the rubber bushing for tracked vehicles was estimated to be about 1.7 million cycles at room temperature (initial stage) and about 400,000 cycles when kept in storage for 3 years. Through this paper, the service life for various rubber parts is expected be predicted and evaluated. This will contribute to improving the durability and reliability of rubber components.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.48-55
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• 2016

The assessment and prediction of service life of a structure are usually under uncertainty so that rational probabilistic concepts and methods have to be applied. Based on these rational assessment and prediction, optimum maintenance strategies to minimize the life-cycle cost and/or maximize the structural safety can be established. The service life assessment and prediction considering maintenance actions generally includes effects of maintenance types and times of the structural components on the service life extensions of structural system. Existing researches on the service life management have revealed the appropriate system modeling considering the correlation among the components is required for system reliability analysis and probabilistic service life estimation. However, the study on correlation among the maintenance actions is still required. This paper deals with such a study for more effective and efficient service life management. In this paper, both the preventive and essential maintenances are considered for the extended service life estimation and management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.19-25
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• 2016

Engineering structures including civil infrastructures require a life-cycle cost and benefit during their service lives. The service life of a structure can be extended through appropriate inspection and maintenance actions. In general, this service life extension requires more life-cycle cost and cumulative benefit. For this reason, structure managers need to make a rational decision regarding the service life management considering both the cost and benefit simultaneously. In this paper, the probabilistic decision tool to determine the optimal service life based on cost-benefit analysis is presented. This decision tool requires an estimation of the time-dependent effective cost-benefit under uncertainty to formulate the optimization problem. The effective cost-benefit is expressed by the difference between the cumulative benefit and life-cycle cost of a deteriorating structure over time. The objective of the optimization problem is maximizing the effective cost-benefit, and the associated solutions are the optimal service life and maintenance interventions. The decision tool presented in this paper can be applied to any deteriorating engineering structure.

• Journal of the Korean Home Economics Association
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• v.41 no.10 s.188
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• pp.129-147
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• 2003

The purpose of study was to improve the quality of the Family Welfare Service in Korea. For the purpose, this study consists of these main subjects. A analysis about the experience and satisfaction of the family life welfare services. And a analysis about the Needs of family life welfare services. The data was collected from 407 low-income families experienced of family life welfare service. The results are as follows They experienced more less $40\%$ of the family life welfare service. It appeared family life welfare service in Korea was still not 'for the family' but 'of the family'. The most of the them experienced or family lire welfare service did not satisfy about services. They hoped to set the family lire welfare services about housing, elderly-care, child-care, job opportunity.

• Journal of Korean Society for Quality Management
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• v.35 no.4
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• pp.61-66
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• 2007

The performance of a building material degrades as time goes by and the failure of the material is often defined as the point at which the performance of the material reaches a pre-specified degraded level. Based on a stochastic deterioration model, a performance based service life prediction method for building materials and components is developed. As a stochastic degradation model, a gamma process is considered and lifetime distribution and service life of a material are predicted using the degradation model. A numerical example is provided to illustrate the use of the proposed service life prediction method.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.103-111
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• 2017

Purpose: Accelerated degradation tests can speed time to market and reduce the test time and costs associated with long term reliability tests to verify the required service life of a product or material. This paper proposes a service life prediction method for components or materials using an accelerated degradation tests based on the relationships between temperature and the rate of failure-causing chemical reaction. Methods: The relationship between performance degradation and the rate of a failure-causing chemical reaction is assumed and least square estimation is used to estimate model parameters from the degradation model. Results: Methods of obtaining acceleration factors and predicting service life using the degradation model are presented and a numerical example is provided. Conclusion: Service life prediction of a component or material is possible at an early stage of the degradation test by using the proposed method.

• Korean Journal of Occupational Health Nursing
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• v.30 no.3
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• pp.79-89
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• 2021

Purpose: This study aimed to confirm the mediating effect of work-life balance organizational culture in the relationship between work-life balance and quality of nursing service for clinical nurses. Methods: Participants included 224 nurses from four hospitals located in D city. Data was collected from 3 to 21 August 2020 using a self-report questionnaires. Descriptive statistics, t-test, one-way ANOVA, Scheffé test, and Pearson's correlation coefficient were used for analysis. The mediating effect was assessed by Baron and Kenny's three-step hierarchical regression analysis and bootstrapping methods. Results: There were significant relationships between work-life balance and work-life balance organizational culture (r=.45, p<.001), work-life balance and quality of nursing service (r=.18, p=.005), and work-life balance organizational culture and quality of nursing service (r=.34, p<.001). Also, work-life balance organizational culture (β=.32, p<.001) showed a total mediating effect on the relationship between work-life balance and quality of nursing service. Conclusion: The development and provision of programs that can improve the work-life balance and establish an organizational culture that supports it will help improve the quality of nursing services.

• Journal of Families and Better Life
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• v.21 no.3
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• pp.133-146
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• 2003

The purpose of this study was to analyze the need for family life welfare service program, and to develope the program for managing in the Community Centers. The survey was conducted by interviewing 356 users and 360 non-users of Community Center, total 716 persons living in Daegu City, from October 8 to October 30 in 2002. The data were analyzed by the SPSS PC+ program applying t-test and ANOVA. The results were as follows : First, overall the needs for family life welfare service program, consisting of education program, facilities management and counseling program, and event program, was higher than 3.7 points. The needs level for event program was a little higher than other two programs. Second, the level of needs for family life welfare service program differed between user group and non-user group of the Community Centers. Third, the level of needs for family life welfare service program varied according to the demographic variables, such as sex, age, marital status, family life cycle, education level, vocation, monthly average income and housing type. Finally, Based on the results of needs analysis, 11 education programs, 4 facilities management and counseling programs and 5 event programs were developed for family life welfare service program. These programs developed in this study could be applied to diverse groups classified by age, social class, family life cycle of citizens. Also the programs should be applied in terms of family unit, as well as individual base to enhance the function of family life.

• Computers and Concrete
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• v.22 no.3
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• pp.319-326
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• 2018

RC (Reinforced Concrete) members are always subjected to loading conditions and have construction joints when constructed on a big scale. Service life for RC structure exposed to chloride attack is usually estimated through chloride diffusion test in sound concrete, however the test is performed without consideration of effect of loading and joint. In the present work, chloride diffusion coefficient is measured in concrete cured for 1 year. In order to evaluate the effect of applied load, cold joint, and mineral admixtures, OPC (Ordinary Portland Cement) and 40%-replaced GGBFS (Ground Granulated Blast Furnace Slag) concrete are prepared. The diffusion test is performed under loading conditions for concrete containing cold joint. Investigating the previous test results for 91 days-cured condition and the present work, changing diffusion coefficients with applied stress are normalized considering material type and cold joint. For evaluation of service life in RC continuous beam with 2 spans, non-linear analytical model is adopted, and service life in each location is evaluated considering the effects of applied stress, cold joint, and GGBFS. From the work, varying service life is simulated under various loading conditions, and the reduced results due to cold joint and tensile zone are quantitatively evaluated. The effect of various conditions on diffusion can provide more quantitative evaluation of chloride behavior and the related service life.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.189-193
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• 2014

SNS (Social Network Service) has evolved to life-friendly service with the combination of local services. Unlike exsiting mobile services, life-friendly service is expected to be personalized with gathering of local information, location information and social network service information. In the process of gathering various kinds of information, Big-data technology and Cloud technology is needed. The effective algorithem has researched for this already, however the privacy protection model hasn't researched enough in life-friendly service or big-data using circumstance. In this paper, the privacy issue is dealt with in terms of 'Structure hole', and the privacy issue comes from big-data technology of life-friendly service.