scholarly journals Estimating and forecasting the spread of COVID-19 in South Korea:  A Bayesian SIHR-based dynamic model with non-pharmaceutical interventions

2020 ◽  
Author(s):  
Hyunho Choi ◽  
Dayun Kang ◽  
Unkyoung Lee ◽  
Jong-Hun Kim ◽  
Sungwha Choi ◽  
...  
Keyword(s):  
South Korea ◽  
Dynamic Model ◽  
Sharp Increase ◽  
Preventive Measures ◽  
Transmission Rate ◽  
Credible Interval ◽  
Dynamic Effects ◽  
Active Testing ◽  
Control And Prevention ◽  
Pharmaceutical Interventions

Abstract Background: As of May 22, 2020, the total number of confirmed COVID-19 cases is over 5 million worldwide and more than 300 thousand people have lost their lives to the virus. South Korea also experienced a sharp increase in late February, but owing to non-pharmaceutical interventions, the number of confirmed cases has been decreasing since March. In this study, we aimed to investigate the transmission dynamics with these effects as well as forecast the spread of COVID-19 in South Korea, using a flexible statistical model.Methods: We analyzed the COVID-19 data obtained at the Korea Centers for Disease Control and Prevention from Feb 18 to April 30. Using a Bayesian susceptible-infectious-hospitalized-removed (SIHR) dynamic model, we estimated the dynamic transmission rate considering the non-pharmaceutical intervention effects and forecast the confirmed cases.Results: The estimated transmission rate without any control effects was 0.4605 with 95% credible interval (0.4468, 0.4745). During the days with effects between February 26 and March 6, the daily transmission rate decreased by about 89.48% of that of the previous day. With consistent control effects, it remained at 0.1549 with 95% credible interval (0.1497, 0.1602). Based on the estimated transmission rate, the forecast number of COVID-19 infections in South Korea showed an overall decreasing pattern.Conclusions: We considered and estimated the dynamic effects of the non-pharmaceutical interventions on COVID-19 using a Bayesian SIHR-based model. This study shows that non-pharmaceutical interventions including active testing, quarantine and isolation, personal preventive measures, and social distancing are crucial to curb the transmission. Our findings contribute to a better understanding of non-pharmaceutical interventions in COVID-19.

Possible preventive measures against the spread of COVID-19- A Review article

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 475-481
Author(s):  
Jotheeswari P ◽  
Yuvaraj M ◽  
Balaji K ◽  
Gunapriya Raghunath ◽  
Kumaresan M
Keyword(s):  
Preventive Measures ◽  
Antiviral Drug ◽  
Preventive Measure ◽  
Thought Process ◽  
Precautionary Measure ◽  
Online Tools ◽  
The World ◽  
Base Of Support ◽  
A Current ◽  
Pharmaceutical Interventions

COVID-19 is a current sensational and dangerous threat that affects millions of people across the world. As the day progresses the rate of growth of COVID-19 drastically increases. No vaccine or specific antiviral drug are active against corona, therefore, preventing the exposure to the virus is the base of support against its spread across the world. Despite the implementation of preventive measures, the rate of virus-infected cases progressively increases which stimulates our thought process to raise a question, whether the preventive measures that we follow are effective against the spread of COVID-19 infection. Evidence from previous literature obtained from various online tools implies multiple preventive measures that should be followed and also illustrates their mechanism of action against the active spread of COVID-19 infection. According to the results from the evidence, we can identify the gold standard preventive measure among the described preventive measures. The precautionary measure encompasses both pharmaceutical interventions and non- pharmaceutical interventions among which non-pharmaceutical measures are superior in the prevention of the developing pandemic. Among the non-pharmaceutical interventions, social distancing is the paramount to other measures in the mitigation of the spread of viral infection.

scholarly journals Modelling the Spatial Distribution of ASF-Positive Wild Boar Carcasses in South Korea Using 2019–2020 National Surveillance Data

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1208
Author(s):  
Jun-Sik Lim ◽  
Timothée Vergne ◽  
Son-Il Pak ◽  
Eutteum Kim
Keyword(s):  
Spatial Distribution ◽  
Risk Factor ◽  
South Korea ◽  
Wild Boar ◽  
African Swine Fever Virus ◽  
Significant Risk ◽  
African Swine Fever ◽  
Credible Interval ◽  
Imperfect Detection ◽  
Wild Boars

In September 2019, African swine fever (ASF) was reported in South Korea for the first time. Since then, more than 651 ASF cases in wild boars and 14 farm outbreaks have been notified in the country. Despite the efforts to eradicate ASF among wild boar populations, the number of reported ASF-positive wild boar carcasses have increased recently. The purpose of this study was to characterize the spatial distribution of ASF-positive wild boar carcasses to identify the risk factors associated with the presence and number of ASF-positive wild boar carcasses in the affected areas. Because surveillance efforts have substantially increased in early 2020, we divided the study into two periods (2 October 2019 to 19 January 2020, and 19 January to 28 April 2020) based on the number of reported cases and aggregated the number of reported ASF-positive carcasses into a regular grid of hexagons of 3-km diameter. To account for imperfect detection of positive carcasses, we adjusted spatial zero-inflated Poisson regression models to the number of ASF-positive wild boar carcasses per hexagon. During the first study period, proximity to North Korea was identified as the major risk factor for the presence of African swine fever virus. In addition, there were more positive carcasses reported in affected hexagons with high habitat suitability for wild boars, low heat load index (HLI), and high human density. During the second study period, proximity to an ASF-positive carcass reported during the first period was the only significant risk factor for the presence of ASF-positive carcasses. Additionally, low HLI and elevation were associated with an increased number of ASF-positive carcasses reported in the affected hexagons. Although the proportion of ASF-affected hexagons increased from 0.06 (95% credible interval (CrI): 0.05–0.07) to 0.09 (95% CrI: 0.08–0.10), the probability of reporting at least one positive carcass in ASF-affected hexagons increased from 0.49 (95% CrI: 0.41–0.57) to 0.73 (95% CrI: 0.66–0.81) between the two study periods. These results can be used to further advance risk-based surveillance strategies in the Republic of Korea.

scholarly journals COVID-19 in South Korea: Proper timing for Easing Mask mandates after COVID-19 Vaccination

2021 ◽  
pp. 1-9
Author(s):  
Yun-Jung Kang
Keyword(s):  
South Korea ◽  
Disease Control ◽  
Prevention And Control ◽  
Control Measures ◽  
Social Distancing ◽  
Proper Timing ◽  
Control And Prevention ◽  
Prevention And Control Measures ◽  
And Control

Abstract As of 25 July 2021, the Korea Disease Control and Prevention Agency reported 1,422 new COVID-19 cases, 188,848 total cases, and 2.073 total deaths (1.10% fatality rates). Since the first SARS-CoV-2 case was reported, efforts to find a treatment and vaccine against COVID-19 have been widespread. Four vaccines are on the WHO’s emergency use listing and are approved of their usage; BNT162b2, mRNA-1273, AZD1222, and Ad26.COV2.S. Vaccines against SARS-CoV-2 need at least 14 days to achieve effectiveness. Thus, people should abide by prevention and control measures, including wearing masks, washing hands, and social distancing. However, a lot of new cases were reported after vaccinations, as many people did not follow the prevention control measures before the end of the 14 days period. There is no doubt we need to break free from mask mandates. But let us not decide the timing in haste. Even if the mask mandates are eased, they should be changed depending on the number of reported cases, vaccinations, as well as prevention and control measures on how circumstances are changing under the influence of mutant coronavirus.

scholarly journals Transmission dynamics of the delta variant of SARS-CoV-2 infections in Daejeon, South Korea

2021 ◽  
Author(s):  
Hari Hwang ◽  
Jun-Sik Lim ◽  
Sun-Ah Song ◽  
Chiara Achangwa ◽  
Woobeom Sim ◽  
...  
Keyword(s):  
South Korea ◽  
Symptom Onset ◽  
Credible Interval ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Nasopharyngeal Swab ◽  
Strict Adherence ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Asymptomatic Patients

Abstract Background The delta variant of SARS-CoV-2 is now the predominant variant worldwide. However, its transmission dynamics remain unclear. Methods We analyzed all case patients in local clusters and temporal patterns of viral shedding using contact tracing data from 405 cases associated with the delta variant of SARS-CoV-2 between 22 June and 31 July 2021 in Daejeon, South Korea. Results Overall, half of the cases were aged under 19 years, and 20% were asymptomatic at the time of epidemiological investigation. We estimated the mean serial interval as 3.26 days (95% credible interval 2.92, 3.60), and 12% of the transmission occurred before symptom onset of the infector. We identified six clustered outbreaks, and all were associated with indoor facilities. In 23 household contacts, the secondary attack rate was 63% (52/82). We estimated that 15% (95% confidence interval, 13–18%) of cases seeded 80% of all local transmission. Analysis of the nasopharyngeal swab samples identified virus shedding from asymptomatic patients, and the highest viral load was observed two days after symptom onset. The temporal pattern of viral shedding did not differ between children and adults (P = 0.48). Conclusions Our findings suggest that the delta variant is highly transmissible in indoor settings and households. Rapid contact tracing, isolation of the asymptomatic contacts, and strict adherence to public health measures are needed to mitigate the community transmission of the delta variant.

scholarly journals SARS-CoV-2 transmission and control in a hospital setting: an individual-based modelling study

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Qimin Huang ◽  
Anirban Mondal ◽  
Xiaobing Jiang ◽  
Mary Ann Horn ◽  
Fei Fan ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Hospital Setting ◽  
Credible Interval ◽  
Hospital Unit ◽  
Early Implementation ◽  
Using Data ◽  
And Control ◽  
The Impact ◽  
Pharmaceutical Interventions ◽  
Outbreak Size

Development of strategies for mitigating the severity of COVID-19 is now a top public health priority. We sought to assess strategies for mitigating the COVID-19 outbreak in a hospital setting via the use of non-pharmaceutical interventions. We developed an individual-based model for COVID-19 transmission in a hospital setting. We calibrated the model using data of a COVID-19 outbreak in a hospital unit in Wuhan. The calibrated model was used to simulate different intervention scenarios and estimate the impact of different interventions on outbreak size and workday loss. The use of high-efficacy facial masks was shown to be able to reduce infection cases and workday loss by 80% (90% credible interval (CrI): 73.1–85.7%) and 87% (CrI: 80.0–92.5%), respectively. The use of social distancing alone, through reduced contacts between healthcare workers, had a marginal impact on the outbreak. Our results also indicated that a quarantine policy should be coupled with other interventions to achieve its effect. The effectiveness of all these interventions was shown to increase with their early implementation. Our analysis shows that a COVID-19 outbreak in a hospital's non-COVID-19 unit can be controlled or mitigated by the use of existing non-pharmaceutical measures.

Corruption control and prevention in the Korean government

2018 ◽  
Vol 7 (3) ◽  
pp. 303-314 ◽  
Author(s):  
Jin-Wook Choi
Keyword(s):  
South Korea ◽  
Qualitative Analysis ◽  
Design Methodology ◽  
Institution Building ◽  
Content Type ◽  
Korean Government ◽  
Policies And Measures ◽  
Control And Prevention ◽  
High Level ◽  
Over Time

Purpose The purpose of this paper is to examine how corruption has changed over time in South Korea and to explore how the corruption control and prevention efforts of the Korean government have been successful and failed. Design/methodology/approach This paper draws on institutional theory to formulate a qualitative analysis to assess the effectiveness of anti-corruption policies and measures, and to identify the strengths and weaknesses of anti-corruption reform efforts in South Korea. Findings This paper argues that while the Korean government has been quite successful in building anti-corruption institutions to control low-level petty corruption, it has failed to institutionalize anti-corruption institutions to curb high-level grand corruption. Originality/value While many studies have attempted to identify the successful factors of fighting corruption, this paper draws a theoretical distinction between institution-building vs institutionalization to examine the success and failure of corruption control and prevention efforts in South Korea.

scholarly journals Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2)

Science ◽  
2020 ◽  
Vol 368 (6490) ◽  
pp. 489-493 ◽  
Author(s):  
Ruiyun Li ◽  
Sen Pei ◽  
Bin Chen ◽  
Yimeng Song ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Transmission Rate ◽  
Credible Interval ◽  
Metapopulation Model ◽  
Mobility Data ◽  
Geographic Spread ◽  
Travel Restrictions ◽  
Rapid Dissemination ◽  
Novel Coronavirus ◽  
Epidemiological Characteristics

Estimation of the prevalence and contagiousness of undocumented novel coronavirus [severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2)] infections is critical for understanding the overall prevalence and pandemic potential of this disease. Here, we use observations of reported infection within China, in conjunction with mobility data, a networked dynamic metapopulation model, and Bayesian inference, to infer critical epidemiological characteristics associated with SARS-CoV-2, including the fraction of undocumented infections and their contagiousness. We estimate that 86% of all infections were undocumented [95% credible interval (CI): 82–90%] before the 23 January 2020 travel restrictions. The transmission rate of undocumented infections per person was 55% the transmission rate of documented infections (95% CI: 46–62%), yet, because of their greater numbers, undocumented infections were the source of 79% of the documented cases. These findings explain the rapid geographic spread of SARS-CoV-2 and indicate that containment of this virus will be particularly challenging.

Dynamic Analysis and Design of Compliant Mechanisms Using the Finite Element Method

2012 ◽  
Vol 163 ◽  
pp. 111-115 ◽  
Author(s):  
Wen Jing Wang ◽  
Li Ge Zhang ◽  
Shu Sheng Bi
Keyword(s):  
Finite Element Method ◽  
Dynamic Model ◽  
Natural Frequency ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
The Finite Element Method ◽  
Dynamic Effects ◽  
Experiment System ◽  
Analysis And Design ◽  
Theoretical Results

Compliant mechanisms gain at least some of their mobility from the deflection of flexible members rather than from movable joints only. Dynamic effects are very important to improving the design of compliant mechanisms. An investigation on the dynamics and synthesis of the compliant mechanisms is presented. The dynamic model of compliant mechanisms is developed at first. The natural frequency and sensitivity are then studied based on the dynamic model. Finally, optimal design of compliant mechanism is investigated. The experimental study of natural frequency is performed. The comparison between the experiment results and the theoretical results verifies the validity of the experiment system and theoretical model.

Optimal Design of the Path of Chain Link Systems

1993 ◽  
Vol 115 (4) ◽  
pp. 793-799 ◽  
Author(s):  
J.-P. Peng ◽  
M. Carpino
Keyword(s):  
Optimal Design ◽  
Dynamic Model ◽  
Constant Velocity ◽  
Small Amplitude ◽  
Optimal Path ◽  
Dynamic Effects ◽  
Chain System ◽  
Chain Link ◽  
Direct Perturbation ◽  
General Method

A general method for the design of the optimal path for a constant velocity chain system is presented. Both the dynamic effects and the kinematic effects of finite sized links have been incorporated into a dynamic model for arbitrary chain paths. A direct perturbation solution is developed for small amplitude oscillations. This model is then used to optimize chain paths for minimum position error and speed variation. An example of an optimized chain path for an oval configuration operating at low speed is presented.

Development and Validation of a Physics-Based, Dynamic Model of a Gas Turbine

2013 ◽  
Author(s):  
Ashley P. Wiese ◽  
Matthew J. Blom ◽  
Michael J. Brear ◽  
Chris Manzie ◽  
Anthony Kitchener
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Dynamic Model ◽  
Test Data ◽  
Thermal Inertia ◽  
Static Model ◽  
Dynamic Effects ◽  
Short Period ◽  
Development And Validation ◽  
State Error

This paper presents and validates a physics-based, dynamic model of a gas turbine. The model is an extension of that proposed by Badmus et al. [1], such that representation of a complete gas turbine is achieved. It includes new models of several gas turbine components, in particular the turbine and compressor, and also applies a well known method for prescribing boundary conditions [10] to the gas path. This model first uses data from a previously published, static model of the same gas turbine to determine this dynamic model’s many so-called ‘forcing terms’. A least-squares optimisation is then undertaken to estimate the shaft inertia and the thermal inertia of system components using transient test data. Importantly, these optimised results are all close to physically reasonable estimates. Further, they show that the shaft dynamics are only significant for a short period at the start of most transients, after which the dynamic effects of thermal storage are dominant. The complete gas turbine model is then validated against transient test data. Whilst the simulated traces demonstrate some steady-state error arising from the static model [12], the overall system dynamics appear to be captured well. Since steady-state error can be integrated out in a control system, this suggests that the proposed dynamic model is appropriate for use in a model-based, gas turbine controller.

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