• Journal of the Korean Data and Information Science Society
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• 제18권3호
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• pp.689-696
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• 2007

This paper considers a Bayesian approach to determine an optimal PM policy with random maintenance quality. Thus, we assume that the quality of a PM action is a random variable following a probability distribution. When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established to formally express and update the uncertain parameters for determining an optimal PM policy. Finally, the numerical examples are presented for illustrative purpose.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 2002년도 제54차 추계 학술대회 연제집
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• pp.45-64
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• 2002

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.83-91
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• 2015

This paper presents preventive and emergency control measures for on line transient stability (security) enhancement. For insecure operating state, generation rescheduling based on a real power generation shift factor (RPGSF) is proposed as a preventive control measure to bring the system back to secure operating state. For emergency operating state, two emergency control strategies namely generator shedding and load shedding have been developed. The proposed emergency control strategies are based on voltage magnitudes and rotor trajectories data available through Phasor Measurement Units (PMUs) installed in the systems. The effectiveness of the proposed approach has been investigated on IEEE-39 bus test system under different contingency and fault conditions and application results are presented.

• 품질경영학회지
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• 제35권4호
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• pp.140-146
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• 2007

In this paper, we consider a periodic imperfect preventive maintenance(PM) policy in which the system's failure rate after each PM remains unchanged. The system undergoes only minimal repairs at failures between PMs. Exact mathematical formula of the expected cost rate per unit time is derived. Optimal number of PMs and optimal maintenance period are derived by minimizing the expected cost rate per unit time. A numerical example is provided to illustrate the proposed approach under Weibull lifetime distribution.

• 한국보건간호학회지
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• 제36권3호
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• pp.347-360
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• 2022

Purpose: The purpose of this study was to identify the risk perception, safety climate and preventive behaviors of COVID-19 infections, and to verify the factors influencing the adoption of preventive behaviors by health care workers. Methods: A mixed-method approach was used based on a survey carried out in a general hospital. Quantitative data (N=181) were collected through a questionnaire and analyzed using multiple regression. Qualitative data (N=8) were collected through individual interviews and analyzed through Colaizzi's phenomological research method. Results: The factors influencing adoption of preventive behaviors by health care workers were safety climate (β=.41, p<.001), education (β=-.20, p=.025), work unit (β=-.16, p=.032), and risk perception (β=.15, p=.020). The explanatory power was 28.3%, and they have shown that these health care workers felt 'the threat of a pandemic like a battlefield', experienced 'struggle with quarantine rules' and realized 'the reality of infection control and the reorganization for change'. Conclusion: The findings of this study indicate that to increase the adoption of infection control preventive behaviors by health care workers when faced with new infectious diseases in the future, it is necessary to establish organizational support and a safe climate. This study confirms the need for preemptive support and education.

• Journal of Preventive Medicine and Public Health
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• 제56권2호
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• pp.100-110
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• 2023

Qualitative research methodology has been applied with increasing frequency in various fields, including in healthcare research, where quantitative research methodology has traditionally dominated, with an empirically driven approach involving statistical analysis. Drawing upon artifacts and verbal data collected from in-depth interviews or participatory observations, qualitative research examines the comprehensive experiences of research participants who have experienced salient yet unappreciated phenomena. In this study, we review 6 representative qualitative research methodologies in terms of their characteristics and analysis methods: consensual qualitative research, phenomenological research, qualitative case study, grounded theory, photovoice, and content analysis. We mainly focus on specific aspects of data analysis and the description of results, while also providing a brief overview of each methodology's philosophical background. Furthermore, since quantitative researchers have criticized qualitative research methodology for its perceived lack of validity, we examine various validation methods of qualitative research. This review article intends to assist researchers in employing an ideal qualitative research methodology and in reviewing and evaluating qualitative research with proper standards and criteria.

• 대한치과의사협회지
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• 제49권8호
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• pp.443-450
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• 2011

The leading paradigm of dentistry had been focused on the rehabilitation treatment that identifies active caries, manages them surgically, and restores their original functions. However, changes in the external environment including the current disease prevalence require dentistry to have a paradigm shift. The new paradigm suggests the detection of caries in their earlier stages over the visual diagnosis of cavities, and the reversal of the incipient caries by non-surgical approach. For this to be achieved, a high-technology detection device recognizing changes in the earlier stages which can not he visually observed is needed. Development of early caries detection device has recently become a major issue in preventive dentistry on account of this need, and QLF(Quantitified Light induced Fluorescence) conspicuously stands out among the newly released devices. In this study, the fundamental concept of QLF(Quantitified Light induced Fluorescence) and the possible clinical applications of the earlier intraoral camera model as well as the recently designed digital camera model will be discussed.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1997년도 추계학술대회발표논문집; 홍익대학교, 서울; 1 Nov. 1997
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• pp.193-196
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• 1997

In this paper we consider a Bayesian theoretic approach to periodic incomplete preventive maintenance with minimal repair at failure. We assume that the system failure rate is increasing as the frequency of PM increases and that the system is replaced at the K-th PM under this maintenance strategy. The optimal policies which minimize the expected cost rates are discussed. We seek the optimal periodic PM interval x and replacement time K under a Weibull failure intensity. Assuming suitable prior distribution for the Weibull parameters, we derive the posterior distribution incorporating failure data and obtain the updated optimal replacement strategies.

• Communications for Statistical Applications and Methods
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• 제13권1호
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• pp.191-204
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• 2006

This paper develops a Bayesian method to derive the optimal sequential preventive maintenance(PM) policy by determining the PM schedules which minimize the mean cost rate. Such PM schedules are derived based on a general sequential imperfect PM model proposed by Lin, Zuo and Yam(2000) and may have unequal length of PM intervals. To apply the Bayesian approach in this problem, we assume that the failure times follow a Weibull distribution and consider some appropriate prior distributions for the scale and shape parameters of the Weibull model. The solution is proved to be finite and unique under some mild conditions. Numerical examples for the proposed optimal sequential PM policy are presented for illustrative purposes.

• 대한가정학회지
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• 제44권4호
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• pp.191-205
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• 2006

The purpose of the study was to develop family-based intervention program to be implemented and disseminated via "Healthy Family-Support Center." This preventive-empowerment program was designed to intervene with parenting mildly handicapped children enrolled at integrated kindergarten. The theoretical backgrounds employed were ecological theory, preventive family-based intervention approach, and theraplay theory. The pretest-posttest control-group design with random assignment was applied. The research model yielded a significant intervention effect(t=-1.294, p<0.05) on mothers' parenting stress. With proven effectiveness of family-based intervention program, the study further discussed why an ecological, family-based intervention model was a relevant alternative to investigate issues in family welfare, and why an individualized family service plan was a relevant tool to deliver services-in-context for the families who needed supports from exo-and macrosystems.