• Journal of the Korean Mathematical Society
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• v.54 no.6
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• pp.1699-1731
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• 2017

In this note, we define and compare some closures which behave somewhat like the radical closure. Using these closures as a starting point allows us to classify all semiprime closures on the nodal curve. Several examples provided show how these closures can differ significantly in the non-Noetherian setting.

• The Journal of Fisheries Business Administration
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• v.37 no.2 s.71
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• pp.33-59
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• 2006

This study describes approaches to fisheries management that restrict access by fishers to an area in some way. When fishery closure is established as a technical conservation measure it is a form of input control as a Korea fisheries management system. There are many compelling reasons why a fisheries manager should seriously consider closed areas and/or time restrictions, either as a complement to other measures or as the primary facet of the Korean fisheries management strategy. Fishery closures have been shown to be effective in many fisheries and are an important tool in the management armoury. In many respects justifications for their use and the process of implementation are likely to be relatively straightforward compared to permanent area closures. From a Korean fisheries management perspective, the benefits that flow from fishery closures are usually less easy to predict than for other management measures. Moreover, even if one accepts that implementation of fisherg clossures will provide higher production levels in adjacent fished areas, the potential benefits may often be in danger of being largely dissipated. If, for example, the fishery remains open access, the increased production is likely to attract new entrants into the fishery, thereby driving it back towards bioeconomic equilibrium. From a Korean wider fisheries conservation perspective, however, fishery closures have important and clearly defensible roles to play and some form of zoning arrangement will often effectively serve conservation values. Given the increasing trend towards the establishment of national networks of fisherg closures, it seems likely that fisheries managers throughout the world will need to ensure that they are familiar with the issues surrounding these approaches. The importance of being explicit about the goals for fishery closures in Korea have been continually emphasised throughout this study. There may, of course, be multiple justifications for the measure, in which case it is important to try and specify them in order of priority.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.31 no.2
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• pp.74-79
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• 2020

Coronavirus disease 2019 (COVID-19), which was first identified in Wuhan, China, in late December of 2019 is rapidly spreading across the globe. The South Korean government has ordered the closure of all schools, as part of its attempts to use social distancing measures to prevent the spread of COVID-19. The effects of the school closures on reducing contagion are generally positive; however, the measure is controversial because of the socioeconomic ripple effect that accompanies it. The author briefly reviewed the existing literature on the mental health aspects of disasters and presents the issues related to school closures due to pandemics, from medical and socioeconomic perspectives and in terms of children's mental health. The results of this review suggest that research on children's mental health in relation to the adoption of school closures as a pandemic mitigation strategy is urgently needed.

• Clinical and Experimental Pediatrics
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• v.64 no.7
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• pp.322-327
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• 2021

School closures during the coronavirus disease 2019 (COVID-19) pandemic have been outlined in studies from different disciplines, including economics, sociology, mathematical modeling, epidemiology, and public health. In this review, we discuss the implications of school closures in the context of the current COVID-19 pandemic. Modeling studies of the effects of school closures, largely derived from the pandemic influenza model, on severe acute respiratory syndrome coronavirus 2 produced conflicting results. Earlier studies assessed the risk of school reopening by modeling transmission across schools and communities; however, it remains unclear whether the risk is due to increased transmission in adults or children. The empirical findings of the impact of school closures on COVID-19 outbreaks suggest no clear effect, likely because of heterogeneity in community infection pressure, differences in school closure strategies, or the use of multiple interventions. The benefits of school closings are unclear and not readily quantifiable; however, they must be weighed against the potential high social costs, which can also negatively affect the health of this generation.

• Journal of the Korean Mathematical Society
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• v.59 no.4
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• pp.805-819
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• 2022

We describe the structure of finite p-groups in which all normal closures of non-normal subgroups have two orders for p > 2.

• Pediatric Infection and Vaccine
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• v.28 no.2
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• pp.57-65
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• 2021

School closures during the coronavirus disease 2019 (COVID-19) pandemic have been outlined in studies from different disciplines, including economics, sociology, mathematical modeling, epidemiology, and public health. In this review, we discuss the implications of school closures in the context of the current COVID-19 pandemic. Modeling studies of the effects of school closures, largely derived from the pandemic influenza model, on severe acute respiratory syndrome coronavirus 2 produced conflicting results. Earlier studies assessed the risk of school reopening by modeling transmission across schools and communities; however, it remains unclear whether the risk is due to increased transmission in adults or children. The empirical findings of the impact of school closures on COVID-19 outbreaks suggest no clear effect, likely because of heterogeneity in community infection pressure, differences in school closure strategies, or the use of multiple interventions. The benefits of school closings are unclear and not readily quantifiable; however, they must be weighed against the potential high social costs, which can also negatively affect the health of this generation.

• Smart Media Journal
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• v.11 no.7
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• pp.9-18
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• 2022

With the outbreak of COVID-19, the world is in unexpected chaos. In particular, the Korean economy, which has a large number of self-employed people, is experiencing enormous damage from COVID-19. The purpose of this study is to analyze the causal impact of start-ups and closures by industry due to the COVID-19 outbreak. For the causal impact analysis, we collected and analyzed 8,312,224 cases of start-up and closure of 190 businesses that occurred on the local administrative license data public site for 11 years from 2010 to 2020. As a result of the analysis of the causal impact of COVID-19, there were 29 industries in which start-ups increased(increase rate 313.14% ~ 6.39%), 23 industries in which start-ups decreased(decrease rate 70.62% ~ 11.27%), 21 industries in which closures increased(increase rate 157.55% ~ 13.57%), and 18 industries in which business closures decreased(reduction rate 49.45% ~ 12.91%). The industries in which start-ups increased and closures decreased due to the COVID-19 outbreak were disinfection, food transportation, and general sales of health functional food. The industries in where start-ups decreased and closures increased due to the COVID-19 outbreak were youth game providing industry, danran pub business, and general game providing industry. It is expected that the results of this study will help practitioners who manage various infectious diseases to understand the causal impact of infectious disease outbreaks and to prepare countermeasures.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.67-70
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• 2000

We introduce the concept of double fuzzy topological spaces as a generalization of intuitionistic fuzzy topological spaces and smooth topological spaces and then investigate some of their properties. Also we introduce the notions of fuzzy (${\gamma}$,s)-interiors and fuzzy (${\gamma}$,s)-closures in double fuzzy topological spaces.

• Communications of the Korean Mathematical Society
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• v.29 no.4
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• pp.555-568
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• 2014

A set with an operation defined on a family of subsets is studied. The operation is used to generalize the topological space itself. The operation defines the operation-open subsets in the set. Relations are studied among two types of the interiors and the closures of subsets. Some properties of maximal operation-open sets are obtained. Semi-open sets and pre-open sets are defined in the sets with operations and some relations among them are proved.

• Journal of agricultural medicine and community health
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• v.40 no.4
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• pp.193-205
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• 2015

Objectives: This study was conducted to find the relationship between oral health conditions of elderly people and closures of public dental health clinics in rural areas. Methods: Oral examinations and surveys were conducted in 2011 from May 11 through November 4 on 383 seniors over 65-years and under 74 years old. Results: The results of this study were as follows: 1. The results of comparative analysis of the usage behaviors of health clinics of subjects in relation to the closures of public dental clinics within the area showed that the usage level and frequency of public health agencies in areas with public dental clinics were high, and that the trend of influence on personal oral health conditions and improvement in prevention was high. When compared to 3 years ago, there was an 11.6 percentage point reduction in areas without public dental clinics (24.4%) compared to areas with public dental clinics (12.8%). 2. The results of comparative analysis of the oral health conditions and behaviors of subjects in relation to the closures of public dental clinics showed that the level of dental caries was high in areas with no public dental clinics, and the number of toothbrush usage and oral health supplemental product usage were shown to be high in areas with public dental clinics. Conclusion: The closures of public dental clinics were found to affect oral health behavior and conditions of elderly people in rural areas.