• 한국신뢰성학회지:신뢰성응용연구
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• 제17권3호
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• pp.246-255
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• 2017

Purpose: This study proposes the optimal PM (preventive maintenance) policy of leased equipment for lessee's decision-making using two types of reliability condition. Methods: We consider reliability threshold based PM model. Equipment reliability is estimated and used as condition variable. The effect of repair for maintenance is imperfect and represented by age reduction factor. Results: We provide two PM policies. Policy 1 is focused on minimized total cost. This policy guarantees reliability threshold until last maintenance action. Policy 2 focus on maintaining reliability threshold during leased period. The proposed approach provides optimal reliability threshold under number of PM. Through result, we finally construct decision-making process for lessee using reliability threshold and end of reliability. Conclusion: This study provides two PM policy for lessee's decision-making. Through numerical example, we get a result of optimal reliability threshold, number of PM, optimum alternative under lessee's reliability condition.

• 대한전기학회논문지:전력기술부문A
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• 제48권3호
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• pp.234-240
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• 1999

This paper presents a new approach for large-scale generator maintenance scheduling optimizations. The generator preventive maintenance scheduling problems are typical discrete dynamic n-dimensional vector optimization ones with several inequality constraints. The considered objective function to be minimized a subset of{{{{ { R}^{n } }}}} space is the variance (i.g., second-order momentum) of operating reserve margin to levelize risk or reliability during a year. By its nature of the objective function, the optimal solution can only be obtained by enumerating all combinatorial states of each variable, a task which leads to computational explosion in real-world maintenance scheduling problems. This paper proposes a new priority search mechanism based on each generator's discrete sensitivity value which was analytically developed in this study. Unlike the conventional capacity-based priority search, it can prevent the local optimal trap to some extents since it changes dynamically the search tree in each iteration. The proposed method have been applied to two test systems (i.g., one is a sample system with 10 generators and the other is a real-world lage scale power system with 280 generators), and the results anre compared with those of the conventional capacith-based search method and combinatorial optimization method to show the efficiency and effectiveness of the algorithm.

• Nutrition Research and Practice
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• 제12권6호
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• pp.479-485
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• 2018

BACKGROUND/OBJECTIVES: Gelidium amansii (GA) contains plenty of agars and various biological substances, which make them a popular functional food to control body weight in previous studies. Unlike previous studies focused on agar in GA, objectives of this study were to investigate the effects of agar-free GA extract (AfGAE) on preventive and treatment models by using diets-induced obese (DIO) C57BL/6J mice. MATERIALS/METHODS: AfGAE were used to test their effects on the prevention (Exp-1) and treatment (Exp-2) against obesity after pilot study in DIO mice. The weight changes of the body and fat tissues and protein expression related to lipid metabolism and inflammation as well as plasma lipid profile and insulin were detected. RESULTS: Although AfGAE did not prevent long-term DIO, it did increase the levels of anti-inflammatory cytokine production and lipolysis protein. We further evaluated various doses of AfGAE in preventive and treatment models. As a result, our findings suggested that an AfGAE administration as a preventive model might be a better approach to achieve its anti-inflammatory and lipolysis-promoting effects in DIO mice. CONCLUSION: Although future studies to investigate the target materials such as polyphenols in AfGAE are required, the result suggests that GA without agar might be a therapeutic tool to improve health conditions related to inflammation.

• 품질경영학회지
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• 제47권1호
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• pp.87-96
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• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• Journal of Preventive Medicine and Public Health
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• 제54권1호
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• pp.1-7
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• 2021

The Korean government's strategy to combat coronavirus disease 2019 (COVID-19) has focused on non-pharmaceutical interventions, such as social distancing and wearing masks, along with testing, tracing, and treatment; overall, its performance has been relatively good compared to that of many other countries heavily affected by COVID-19. However, little attention has been paid to health equity in measures to control the COVID-19 pandemic. The study aimed to examine the unequal impacts of COVID-19 across socioeconomic groups and to suggest potential solutions to tackle these inequalities. The pathways linking social determinants and health could be entry points to tackle the unequal consequences of this public health emergency. It is crucial for infectious disease policy to consider social determinants of health including poor housing, precarious working conditions, disrupted healthcare services, and suspension of social services. Moreover, the high levels of uncertainty and complexity inherent in this public health emergency, as well as the health and socioeconomic inequalities caused by the pandemic, underscore the need for good governance other than top-down measures by the government. We emphasize that a people-centered perspective is a key approach during the pandemic era. Mutual trust between the state and civil society, strong accountability of the government, and civic participation are essential components of cooperative disaster governance.

• 인터넷정보학회논문지
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• 제24권5호
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• pp.67-73
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• 2023

The Digital Age calls for improvement of information literacy particularly among children and youth who are vulnerable to cybergrooming. Taking an interdisciplinary approach by leveraging our team's expertise including child and adolescent development, data analytics, and cybersecurity, this study proposes an interactive artificial intelligence (AI)-based preventive simulation program that raises youth knowledge and awareness about the risk of cybergrooming as well as increases resilient self-efficacy in their cybersecurity-relevant skills. The primary purpose of this project is to evaluate the effectiveness of the simulation program on preventing cybergrooming. More specifically, this study is designed to examine developmental changes in self-efficacy of cybersecurity-relevant skills among youth participants as a function of the preventive simulation program. Further, this study will identify risk and protective factors that explain interindividual differences in the ability of children and youth either to fall victim to advances from a cyber predator or to recognize and deter such threats. The preliminary data will help improve the effectiveness of the preventive simulation program as well as the methods of implementation to large groups of youth. The findings from the proposed study will contribute to making specific recommendations to parents, educators, practitioners, and policy makers for the prevention of cybergrooming.

• Journal of Preventive Medicine and Public Health
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• 제38권3호
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• pp.259-266
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• 2005

Recently much attention has been paid to the effect of neighborhood characteristics on the health of individuals, independent of individual demographic and/or socioeconomic characteristics. Although many empirical studies of a kind, mostly based on Western society, have appeared on various international journals, few studies have shown empirical evidence of neighborhood characteristics as an independent and significant risk factor of ill health in Korea. This paper discusses possible reasons that neighborhood seems to be neither significant nor substantial regarding its impact on the health of Koreans. Addressing the uniqueness of Korean society regarding the concept of neighborhood, attributes of neighborhoods, and methodological challenges, authors suggest that more sophisticated conceptual and methodological approach, specific to Korean society, should enable to reveal the effect of neighborhood characteristics on individual health in Korea.

• Journal of Preventive Medicine and Public Health
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• 제38권3호
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• pp.237-240
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• 2005

Social epidemiology is a sub-discipline of epidemiology explicitly investigating social determinants of population distributions of health, disease, and well-being. Persistent pattern of social inequalities in health in spite of the broad improvement in the physical environment over the last centuries necessitated the development of this field as an approach to understand disease etiology that incorporates social experiences as more direct determinant of health. Social epidemiology incorporates theories, measurement tools, and techniques from a wide variety of other social sciences. A population perspective, the social context of behavior, contextual multilevel analysis, a developmental and life-course perspective, and general susceptibility to disease are the most important guiding concepts in social epidemiology.

• Journal of Preventive Medicine and Public Health
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• 제50권4호
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• pp.262-267
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• 2017

Objectives: The US ranks ninth in obesity in the world, and approximately 7% of US adults experience major depressive disorder. Social isolation due to the stigma attached to obesity might trigger depression. Methods: This paper examined the impact of obesity on depression. To overcome the endogeneity problem, we constructed pseudopanel data using the Behavioral Risk Factor Surveillance System from 1997 to 2008. Results: The results were robust, and body mass index (BMI) was found to have a positive effect on depression days and the percentage of depressed individuals in the population. Conclusions: We attempted to overcome the endogeneity problem by using a pseudo-panel approach and found that increases in the BMI increased depression days (or being depressed) to a statistically significant extent, with a large effect size.

• 대한예방한의학회지
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• 제3권1호
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• pp.67-82
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• 1999

This study was performed to investigate out-of-pocket money among medical expenses of an oriental medical university hospital by the use of internal data of an oriental hospital because medical insurance program data could not show us insuree's out-of-pocket money among medical expenses. The purpose of this study was to analyze out-of-pocket money among medical expenses of ambulatory and hospitalized patients. Under this purpose, We analyzed actual medical expenses data of 1389 out-patients and 858 in-patients of the oriental medical university hospital with 90 beds that could be approach to internal data from July 1, 1998 to March 31, 1999. The major findings are as follows : 1. In ambulatory patients, the cost share ratio of insuree & that of insurer was 90 : 10 respectly. 2. In hospitalized patients, the cost share ratio of insuree & that of insurer was 72 : 28 respectly.