• Journal of Computing Science and Engineering
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• v.8 no.1
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• pp.1-10
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• 2014

The Bacterial Foraging Optimization Algorithm is a swarm intelligence optimization algorithm. This paper first analyzes the chemotaxis, as well as elimination and dispersal operation, based on the basic Bacterial Foraging Optimization Algorithm. The elimination and dispersal operation makes a bacterium which has found or nearly found an optimal position escape away from that position, which greatly affects the convergence speed of the algorithm. In order to avoid this escape, the sphere of action of the elimination and dispersal operation can be altered in accordance with the generations of evolution. Secondly, we put forward an algorithm of an adaptive adjustment of step length we called improved bacterial foraging optimization (IBFO) after making a detailed analysis of the impacts of the step length on the efficiency and accuracy of the algorithm, based on chemotaxis operation. The classic test functions show that the convergence speed and accuracy of the IBFO algorithm is much better than the original algorithm.

• The Plant Pathology Journal
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• v.32 no.6
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• pp.508-518
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• 2016

Early blight of tomato caused by Alternaria solani, is responsible for severe yield losses in tomato. The conidia survive on soil surface and old dry lower leaves of the plant and spread when suitable climatic conditions are available. Macroclimatic study reveals that highest inoculum concentration of Alternaria spores appeared in May 2012 to 2013 and lowest concentration during January 2012 to 2013. High night temperature positively correlated and significantly (P < 0.01) involved in conidial spore dispersal and low relative humidity (RH) displayed significant (P < 0.05) but negative correlation with conidial dispersal. The objective of the study was to modify microclimatic conditions of tomato crop canopy which may hamper conidial dispersal and reduce disease severity. We evaluated effect of marigold intercropping and plastic mulching singly and in consortia on A. solani conidial density, tomato leaf damage and microclimatic parameters as compar to tomato alone (T). Tomato-marigold intercropping-plastic mulching treatment (T + M + P) showed 35-39% reduction in disease intensity as compared to tomato alone. When intercropped with tomato, marigold served as barrier to conidial movement and plastic mulching prevented evapotranspiration and reduced the canopy RH that resulted in less germination of A. solani spores. Marigold intercropping and plastic mulching served successfully as physical barrier against conidial dissemination to diminish significantly the tomato foliar damage produced by A. solani.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.546-552
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• 1996

The applicability of chitosan, a biodegradable natural polymer, as the coating material to prevent the dispersal of the spores of the apple white rot agent Botryosphaeria dothidea, was investigated. The physical properties of mixed chitosan/polyvinyl alcohol(PVA) film showed the increased physical properties for film formation, such as tensil strength, elongation, and viscosity, compared to either chitosan or PVA film. The FT-IR spectra of chitosan/PVA film indicated that the film was formed by simple blending not by any new synthetic bond. The chitosan and chitosan/PVA film showed effective antifungal activity on B. dothidea. The formed films were well decomposed by ASTM strains used for biodegradability test, on the other hand, the PVA film could not be decomposed by above standard strains. The field test at apple orchard showed that the dispersal of B. dothidea spores could be effectively reduced by coated film, especially by chitosan/PVA film. The spore dispersal was reduced upto 97.0% by 1.0% chitosan/5.0% PVA film during 4 months.

• Journal of the Korean Regional Science Association
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• v.9 no.1
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• pp.45-63
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• 1993

University enrollment has long been regarded as one of the major factors inducing population concentration in Seoul and the Capital Region of Korea. Consequently, since early 1980's increases in enrollment and new establishments of extention universities beyond the boundary of Seoul, has been promoted, while university enrollment quota in Seoul has been strictly controlled. The degree of actual population dispersal, however, resulting from such a university enrollment policy has not been empirically tested. This paper aims at: First, identifying the trend of population growth and evolution process of the university enrollment policy in the Capital Region; Second, comparing the degree of influence of university enrollment on population concetration factors; Third, measuring actual effect of the enrollment control on population dispersal out of Seoul and the Capital Region. Major findings are as follows: First, only a week correlation between population and university enrollment growth trends was found; Second, the relative degree of influence on population concentration in the Capital Region, were order, in the order of magnitude, the physical amenity factor, the socio-cultural amenity factor, the employment climate factor and the educational factor. Third, and most improtant, based on the comparison of spatial distribution of graduated high schools and current residence of the selected university students, the gap between the two distributions was revealed and the inter-regional student population movement was estimated. The result shows that in Seoul's case about one-half of and in Kyunggi Province's case about one-fifth of university enrollment size, contributes to population concentration into Seoul. Fourth, as to the universities outside of the Capital Region, little effect in the case of universities located within the commuting distance, and a little effect on population dispersal in the case of universities located beyond commuting distance, were found. In sum, it seems clear that university enrollment policy in the Capital Region, especially in Inchon/Kyunggi Province has not been effective on student population dispersal out of Seoul and the Capital Region. Therefore, it is strongly recommended that university enrollment policy be throughly re-examined from its goal to the implementation means.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.306-309
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• 2000

The black pine bast scale (BPBS), Matsucoccus thunbergianae, causes serious damage to Japanese black pine forests in the southern part of Korean peninsula. After first detection of its damage in Kohung, Chonnam Province in 1963, the distribution has been expanding gradually year by year. Since 1983, extensive surveys for BPBS distributions have been carried out by Korea Forest Research Institute. We used cumulative data for BPBS distribution and analyzed the dispersal pattern. We divided expansions into three directions such as north along the west coast, northeast towards the inland, and east along the south coast. In the direction of northeast the dispersal rate was approximately 4.3km per year in dense forests of Japanese black pine, but it slowed down since the early 1990s. The annual dispersal rates were approximately 5.9 and 3.3km in north and east directions, respectively.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.87-102
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• 2019

Most chronic wounds persist in the inflammatory phase during wound healing due to the biofilm. Biofilms are resistant to antibiotics, weakening penetration, resistance to biocides and weakening local immune responses. The biofilm is firmly attached to the surrounding tissues and is very difficult to remove. Therefore, strategies to remove hard biofilms without damaging surrounding tissue are very important. One of possible strategies is dispersal. So many studies have been done to develop new strategies using dispersal mechanisms. In this review paper, especially chemotaxis, phage therapy, polysaccharides, various enzymes (glycosidases, proteases, and deoxyribonucleases), surfactants, dispersion signals, autoinducers, inhibitors were introduced. Combination therapies with other therapies such as antibiotic therapy were also introduced. It is expected that the possibility of treatment of chronic wound infection using the knowledge of the biofilm dispersal mechanisms presented in this paper will be higher.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.15 no.4
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• pp.291-306
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• 2011

We consider the second order Strang splitting method to approximate the solution to the KdV equation. The model equation is split into three sets of initial value problems containing convection and dispersal terms separately. TVD MUSCL or MUSCL scheme is applied to approximate the convection term and the second order centered difference method to approximate the dispersal term. In time stepping, explicit third order Runge-Kutta method is used to the equation containing convection term and implicit Crank-Nicolson method to the equation containing dispersal term to reduce the CFL restriction. Several numerical examples of weakly and strongly dispersive problems, which produce solitons or dispersive shock waves, or may show instabilities of the solution, are presented.

• The Plant Pathology Journal
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• v.19 no.4
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• pp.205-209
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• 2003

Dispersal of citrus bacterial canker caused by Xanthomonas axonopodis pv. citri on Unshiu orange was investigated in naturally infested nursery plot at Seogwipo in Jeju island, Korea. Based on phage detection, over 2% of the bacterial pathogen over-wintered in canker lesions and started to multiply in late May. However, symptoms were first observed 1 month after the phage detection. The disease dispersed non-directionally to nearby plants possibly because of indirect dissemination of the bacterium by rain splashes. The disease increased from late June to late August and decreased thereafter. Population of phage increased constantly, however, disease occurrence somewhat fluctuated due to environmental factors. Disease incidence and severity were correlated with rainfall with wind that occurred 14-32 days earlier from late May to late August.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.367-370
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• 2005

The risk from genetically modified (GM) plants results from the possibility of gene contamination producing adverse effects on biological diversity by introducing herbicide or insect resistance into related plants or weeds (NAS 2002). The concern about the leakage of genes from GM plants into the environment has primarily focused on pollen that could be wind-borne for long distances. During the period of fisk assessment in Japan, physical containment is applied as a measure of reducing gene flow via the dispersal of pollen from GM plants into the surrounding environment In this study, we tried to estimate the effect of physically contained greenhouse covered by 1-mm fine mesh to reduce pollen dispersal by researching cross pollination rate between non-GM yellow maize in a greenhouse and silver maize outside the greenhouse.

• Journal of Environmental Impact Assessment
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• v.27 no.3
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• pp.291-306
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• 2018

This study was designed to predict potential habitat of Japanese evergreen oak (Quercus acuta Thunb.) in Korean Peninsula considering its dispersal ability under climate change. We used a species distribution model (SDM) based on the current species distribution and climatic variables. To reduce the uncertainty of the SDM, we applied nine single-model algorithms and the pre-evaluation weighted ensemble method. Two representative concentration pathways (RCP 4.5 and 8.5) were used to simulate the distribution of Japanese evergreen oak in 2050 and 2070. The final future potential habitat was determined by considering whether it will be dispersed from the current habitat. The dispersal ability was determined using the Migclim by applying three coefficient values (${\theta}=-0.005$, ${\theta}=-0.001$ and ${\theta}=-0.0005$) to the dispersal-limited function and unlimited case. All the projections revealed potential habitat of Japanese evergreen oak will be increased in Korean Peninsula except the RCP 4.5 in 2050. However, the future potential habitat of Japanese evergreen oak was found to be limited considering the dispersal ability of this species. Therefore, estimation of dispersal ability is required to understand the effect of climate change and habitat distribution of the species.