• Korean System Dynamics Review
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• v.7 no.2
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• pp.215-226
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• 2006

A conceptual system dynamics model is developed to represent the dynamic mechanism between the number of hepatitis B virus and the defense system of the body. The simulation results shows that the model behaves within the reasonable ranges. The developed conceptual model is a first attempt to quantify the dynamic mechanisms of the hepatitis B virus, where only feedback structures are considered without bio-organism data. The next step would be to incorporate the model with bio-organism theory and to carry out case studies to identify personal characteristics. Since the current model is a conceptual model where quantitative results are not based on the sound background, the usage is limited only within the qualitative basis. It could be a effective educational tool for the patients. It also shows what-to-do lists in order to be used for forecast purposes.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.41-49
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• 2014

Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.

• IMMUNE NETWORK
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• v.13 no.5
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• pp.163-167
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• 2013

The dynamics of the virus-host interface in the response to respiratory virus infection is not well-understood; however, it is at this juncture that host immunity to infection evolves. Respiratory viruses have been shown to modulate the host response to gain a replication advantage through a variety of mechanisms. Viruses are parasites and must co-opt host genes for replication, and must interface with host cellular machinery to achieve an optimal balance between viral and cellular gene expression. Host cells have numerous strategies to resist infection, replication and virus spread, and only recently are we beginning to understand the network and pathways affected. The following is a short review article covering some of the studies associated with the Tripp laboratory that have addressed how respiratory syncytial virus (RSV) operates at the virus-host interface to affects immune outcome and disease pathogenesis.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.23 no.1
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• pp.39-63
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• 2019

In this paper, we study the effect of Cytotoxic T Lymphocyte (CTL) and antibody immune responses on the virus dynamics with both virus-to-cell and cell-to-cell transmissions. The infection rate is given by Holling type-II. We first show that the model is biologically acceptable by showing that the solutions of the model are nonnegative and bounded. We find the equilibria of the model and investigate their global stability analysis. We derive five threshold parameters which fully determine the existence and stability of the five equilibria of the model. The global stability of all equilibria of the model is proven using Lyapunov method and applying LaSalle's invariance principle. To support our theoretical results we have performed some numerical simulations for the model. The results show the CTL and antibody immune response can control the disease progression.

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.295-304
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• 1994

This paper describes some preliminary attempts to formulate simple mathematical models of the transmission dynamics of HIV infection in homosexual communities. In conjunction with a survey of the available epidemiological data on HIV infection and the incidence of AIDS, the model is used to assess how various processes influence the course of the initial epidemic following the introduction of the virus. Models of the early stages of viral spread provide crude methods for estimating the basic reproductive rate of the virus, given a knowledge of the incubation period of AIDS and the initial doubling time of the epidemic. More complex models are formulated to assess the influence of heterogeneity in sexual activity. This latter factor is shown to have a major effect on the predicted pattern of the epidemic.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1515-1526
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• 2022

Eukaryotic chromatin is highly organized in the 3D nuclear space and dynamically regulated in response to environmental stimuli. This genomic organization is arranged in a hierarchical fashion to support various cellular functions, including transcriptional regulation of gene expression. Like other host cellular mechanisms, viral pathogens utilize and modulate host chromatin architecture and its regulatory machinery to control features of their life cycle, such as lytic versus latent status. Combined with previous research focusing on individual loci, recent global genomic studies employing conformational assays coupled with high-throughput sequencing technology have informed models for host and, in some cases, viral 3D chromosomal structure re-organization during infection and the contribution of these alterations to virus-mediated diseases. Here, we review recent discoveries and progress in host and viral chromatin structural dynamics during infection, focusing on a subset of DNA (human herpesviruses and HPV) as well as RNA (HIV, influenza virus and SARS-CoV-2) viruses. An understanding of how host and viral genomic structure affect gene expression in both contexts and ultimately viral pathogenesis can facilitate the development of novel therapeutic strategies.

• The Plant Pathology Journal
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• v.40 no.5
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• pp.551-558
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• 2024

Papaya leaf curl China virus (PaLCuCNV) is a damaging plant pathogen causing substantial losses to crop. The complete genomes of three PaLCuCNV isolates from Ageratum conyzoides were obtained and combined with the 68 reference isolates in GenBank for comprehensive genetic diversity analyses using specialized computational tools. Sequence alignment revealed nucleotide sequence similarity ranging from 85.3% to 99.9% among 71 PaLCuCNV isolates. Employing phylogenetic analysis, 71 PaLCuCNV sequences were clustered into five groups, with no significant correlation observed between genetic differentiation and either host species or geographical origin. Additionally, 13 recombination events across all PaLCuCNV isolates were identified. Genetic diversity analysis indicated the ongoing expansion and evolution of PaLCuCNV populations, supported by a neutral model. Moreover, significant genetic differentiation was observed among distinct viral populations, primarily attributed to genetic drift. Overall, our findings provide valuable insights into the detection, genetic variation, and evolutionary dynamics of PaLCuCNV.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.1059-1062
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• 2012

• Journal of applied mathematics & informatics
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• v.41 no.1
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• pp.107-121
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• 2023

An epidemic infectious disease model consists of six compartments viz. Susceptible, Exposed, Infected, Quarantine, Recovered, and Virus with nonlinear saturation incidence rate is proposed to know the viral disease dynamics. There exist two biological equilibrium points for the model system. The system's local and global stability is done through Lyapunov's direct method about equilibrium points. The sensitivity analysis has been performed for the basic reproduction number and equilibrium points through the normalized forward sensitivity index. Sensitivity analysis shows that virus growth and quarantine rates are more sensitive parameters. In support of mathematical conclusions, numerical experimentation has been shown.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.81-88
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• 2014

Accurate wind data is essential for predicting airborne spread of virus. OpenFOAM was used for computational fluid dynamics (CFD) simulation procedure which is under GNU GPL (General Public License). Using complex terrain, DEM (Digital Elevation Map) that was prepared from GIS information covering a research site is converted to a three dimensional surface mesh that is composed by quad and full hexahedral space meshes. Around this surface mesh, an extended computational domain volume was designed. Atmospheric flow boundary conditions were used at inlet and roughness height and was considered at terrain by using rough wall function. Two different wind conditions that was relatively stable during certain periods were compared in 3 different locations for validating the accuracy of the CFD computed solution. The result shows about 10 % of difference between the calculated result and measured data. This procedure can simulate a prediction of time-series data for airborne virus spread that can be used to make a web-based forecasting system of airborne virus spread.