• Journal of Preventive Medicine and Public Health
• /
• 제56권5호
• /
• pp.481-484
• /
• 2023

Epidemiological models, also known as host-agent-vector-environment models, are utilized in public health to gain insights into disease occurrence and to formulate intervention strategies. In this paper, we propose an epidemiological model that incorporates both conventional measures and tobacco endgame policies. Our model suggests that conventional measures focus on relationships among agent-vector-host-environment components, whereas endgame policies inherently aim to change or eliminate those components at a fundamental level. We also found that the vector (tobacco industry) and environment (physical and social surroundings) components were insufficiently researched or controlled by both conventional measures and tobacco endgame policies. The use of an epidemiological model for tobacco control and the tobacco endgame is recommended to identify areas that require greater effort and to develop effective intervention measures.

• 대한수학회논문집
• /
• 제13권3호
• /
• pp.643-653
• /
• 1998

In this paper, we analyze a system for an epidemiological model which has a double zero eigenvalue at certain parameter values.

• Journal of applied mathematics & informatics
• /
• 제38권5_6호
• /
• pp.375-406
• /
• 2020

The anti-predator factor due to fear of predator in eco- epidemiological models has a great importance and cannot be evaded. The present paper consists of a modified Lesli-Gower predator-prey model with contagious disease in the predator population only and also consider the fear effect in the prey population. Boundedness and positivity have been studied to ensure the eco-epidemiological model is well-behaved. The existence and stability conditions of all possible equilibria of the model have been studied thoroughly. Considering the fear constant as bifurcating parameter, the conditions for the existence of limit cycle under which the system admits a Hopf bifurcation are investigated. The detailed study for direction of Hopf bifurcation have been derived with the use of both the normal form and the central manifold theory. We observe that the increasing fear constant, not only reduce the prey density, but also stabilize the system from unstable to stable focus by excluding the existence of periodic solutions.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제13권3호
• /
• pp.181-188
• /
• 2009

Hundreds of thousands of South Korean protesters staged candlelight vigils and demonstrations against US beef imports in 2008. The problems, however, went far beyond that of beef imports. The political party veterans, who lost the presidential election, exploited labor unions that were discontent with the economy and ideological student groups to weaken the majority party. In this study, an epidemiological model is constructed with a system of three nonlinear differential equations. The model seeks to examine the dynamics of the system through stability analysis. Two threshold conditions that spread the protests are identified and a sensitivity analysis on the conditions is performed to isolate the parameters to which the system is most responsive. The results are also explored by deterministic simulations. This model can be easily modified to apply to other protests that may occur in various circumstances.

• Journal of Radiation Protection and Research
• /
• 제42권2호
• /
• pp.130-140
• /
• 2017

Background: With the need for a domestic level 3 probabilistic safety assessment (PSA), it is essential to develop a Korea-specific code. Health effect assessments study radiation-induced impacts; in particular, long-term health effects are evaluated in terms of cancer risk. The objective of this study was to analyze the latest cancer risk models developed by foreign organizations and to compare the methodology of how they were developed. This paper also provides suggestions regarding the development of Korean cancer risk models. Materials and Methods: A review of cancer risk models was carried out targeting the latest models: the NUREG model (1993), the BEIR VII model (2006), the UNSCEAR model (2006), the ICRP 103 model (2007), and the U.S. EPA model (2011). The methodology of how each model was developed is explained, and the cancer sites, dose and dose rate effectiveness factor (DDREF) and mathematical models are also described in the sections presenting differences among the models. Results and Discussion: The NUREG model was developed by assuming that the risk was proportional to the risk coefficient and dose, while the BEIR VII, UNSCEAR, ICRP, and U.S. EPA models were derived from epidemiological data, principally from Japanese atomic bomb survivors. The risk coefficient does not consider individual characteristics, as the values were calculated in terms of population-averaged cancer risk per unit dose. However, the models derived by epidemiological data are a function of sex, exposure age, and attained age of the exposed individual. Moreover, the methodologies can be used to apply the latest epidemiological data. Therefore, methodologies using epidemiological data should be considered first for developing a Korean cancer risk model, and the cancer sites and DDREF should also be determined based on Korea-specific studies.

• Journal of Veterinary Science
• /
• 제24권2호
• /
• pp.21.1-21.5
• /
• 2023

Under the current African swine fever (ASF) epidemic situation, a science-based ASF-control strategy is required. An ASF transmission mechanistic model can be used to understand the disease transmission dynamics among susceptible epidemiological units and evaluate the effectiveness of an ASF-control strategy by simulating disease spread results with different control options. The force of infection, which is the probability that a susceptible epidemiological unit becomes infected, could be estimated by applying an ASF transmission mechanistic model. The government needs to plan an ASF-control strategy based on an ASF transmission mechanistic model.

• Journal of Medicine and Life Science
• /
• 제20권3호
• /
• pp.107-114
• /
• 2023

Epidemiological control of coronavirus disease 2019 (COVID-19) is needed to estimate the infection period of confirmed cases and identify potential cases. The present study, targeting confirmed cases for which the time of COVID-19 symptom onset was disclosed, aimed to investigate the relationship between intervals (day) from symptom onset to testing the cycle threshold (CT) values of real-time reverse transcription-polymerase chain reaction. Of the COVID-19 confirmed cases, those for which the date of suspected symptom onset in the epidemiological investigation was specifically disclosed were included in this study. Interval was defined as the number of days from symptom onset (as disclosed by the patient) to specimen collection for testing. A locally weighted regression smoothing (LOWESS) curve was applied, with intervals as explanatory variables and CT values (CTR for RdRp gene and CTE for E gene) as outcome variables. After finding its non-linear relationship, a polynomial regression model was applied to estimate the 95% confidence interval values of CTR and CTE by interval. The application of LOWESS in 331 patients identified a U-shaped curve relationship between the CTR and CTE values according to the number of interval days, and both CTR and CTE satisfied the quadratic model for interval days. Active application of these results to epidemiological investigations would minimize the chance of failing to identify individuals who are in contact with COVID-19 confirmed cases, thereby reducing the potential transmission of the virus to local communities.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제14권4호
• /
• pp.275-284
• /
• 2010

Deliberate self-harm (DSH) is the act of deliberately harming your own body, such as cutting or burning yourself, without suicidal intent. It has especially become a problem among adolescents and college-age students in institutional settings such as boarding schools, Greek houses, detention centers and hospitals. We focus on contagion of DSH among adolescents and young adults by creating a deterministic epidemiological model. We study the impact of actual peer pressure, virtual peer pressure (the Internet) and treatment analytically in terms of a basic reproduction number through stability analysis of a system of ordinary differential equations. All parameters are approximated and results are also explored by simulations. The model shows that DSH is present in an endemic state in the population considered, and the control strategies are discussed.

• 대한안전경영과학회지
• /
• 제25권2호
• /
• pp.9-15
• /
• 2023

The Severe Disaster Punishment Act had recently been established in order to promote safety and health (OSH) management system for severe accident prevention. OSH management system is primarily designed based on risk assessments; however, companies in industries have been experiencing difficulties in hazard identification and selecting proper measures for risk assessments and accident prevention. This study intended to introduce an accident analysis method based on epidemiological model in finding hazard and preventive measures. The accident analysis method employed in this study was proposed by the U.S. Department of Energy. To demonstrate the effectiveness of the accident analysis method, this study applied it to two accident cases occurred in construction and manufacturing industries. The application process and results of this study can be utilized in improving OSH management system and preventing severe accidents.

• 한국식품영양과학회:학술대회논문집
• /
• 한국식품영양과학회 2004년도 Annual Meeting and International Symposium
• /
• pp.24-36
• /
• 2004

Polyphenolic flavonoids are among a wide variety of phytochemicals present in the human diet. Basic research, animal model, and human studies suggest flavonoid intake may reduce the risk of several age-related chronic diseases. The vast number of flavonoids and mixtures of their subclasses, including flavonols, flavones and flavanones, and the variety of agricultural practices that affect their concentration in foods have presented a challenge to the development of adequate food composition databases for these com-pounds. Nonetheless, dietary assessments have been applied to cohort and case-control epidemiological studies and several reveal an inverse association with risk of some forms of cancer, cardiovascular disease, and other chronic conditions. Those observational studies that have examined these relationships with regard to flavonols, flavones, and flavanones are reviewed. The requirement for caution in interpreting these studies is discussed with regard to the limited information available on the bioavailability and biotransformation of these flavonoids. As the totality of the available evidence on these flavonoids suggests a role in the prevention of cancer and cardiovascular disease, further research is warranted, particularly in controlled clinical trials.