• Korean journal of applied entomology
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• v.18 no.1 s.38
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• pp.15-21
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• 1979

To determine the population regulation mechanism of the Green rice leafhopper (Nephotettix cincticeps Uhler), the responses of the population increase to initial densities and the effect of host conditions and temperatures during developmental period were investigated. In the out door experiment, the increasing ratio of population density of this pest was reduced as initial density increased and this density-dependent effect was differ in accordance with host condition. Host conditioning through feeding resulted in reduction in numbers of eggs produced and it seemed to be affected by some inhibiting materials secreted by the pest during feeding. though the direct effect of feeding can't be excluded. The population growth was related with population density and host stage. Thus in late planted units, the host stage was favourable to the growth of population at low initial insect density but unfavourable at relatively high initial insect density and in early planted units, vice versa. The temperature during developmental stages definitely affected the determination of sex ratio of adult population and reduced numbers of eggs produced. The most favourable temperature to the population increase was $290^{\circ}C$, and at high temperature, $33^{\circ}C$, severe reduction of fecundity was shown ana it seemed to be caused by the simple reduction in numbers of eggs produced.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.134-144
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• 2001

This study was conducted to investigate physicochemical and microbiological properties during composting process when pig manure was composted with some bulking agents(Saw dust, Rice hull, Crushed wood). The pig manure consisted of 2.95% total nitrogen, 4.55% $P_2O_5$, 2.07% $K_2O$, 81.2% organic matter and 14.0 C/N, dry base. The inorganic content of bulking agents were similar one another, and C/N ratio was Saw dust 392. Rice hull 91.5, Crushed wood 266. The temperature of Saw dust composting slowly increased at initial stage, whereas one of Rice hull and Crushed wood rapidly increased and stabilized similarly to outdoor temperature after about 2 month. The pH of compost increased during initial 1 month after decreasing, but thereafter decreased rapidly. The C/N ratio rapidly decreased at initial stage, and it slowly decreased after 1 month. Total nitrogen somewhat increased according to composting process. Ammonium-nitrogen increased until 60th day, and thereafter it was rapidly inclined to decrease. The population of aerobic bacteria, Bacillus spp., actinomycetes and fungi increased up to > $10^{10}cfu\;g^{-1}$ fresh weight, > $10^7$, > $10^8$ and > $10^6$, respectively in Rice hull and Crushed wood composting, and more than ones in Saw dust composting, and specially actinomycetes. The persuasive Bacillus spp. isolated from composting process were B. lentimorbus, B. licheniformis, B. pumilus, B. megaterium, etc.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.1
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• pp.69-84
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• 1993

In order to determine the optimum operational paramsters in cow manure composting, 4 laboratory scale composters were established. The cow manure was mixed with certain amount of saw dust to adjust the initial C/N ratio to 24, initial pH to 6.9 and composting was performed with varying operational conditions. It was found that the optimum aeration rate was 1000 ml/min kg. VS, the optimum moisture content 50% and no significant difference was found with different initial pH condition. Microorganisms were counted under the optimum conditions determined in this study. At the end of the experimental period, the number of bacteria, actinomycetes and fungi was $1.5{\times}10^9$ cells, $1.1{\times}10^8$ cells and $3.0{\times}10^8$ cells/g dry compost, respectively. At day 0, the number of coliforms, fecal coliforms and fecal streptococci was $3.1{\times}10^3$ cells, $7.5{\times}10^2$ cells and $5.6{\times}103$ cells/g dry composting material, respectively. Their population was decreased with time lapse, However, their survival time was longer than those reported by other researchers. Microorganisms were identified at the end of the experiment. Genus Bacillus was the most dominant comprising 89.3% of the total population. Among the Genus Bacillus, B. circulans compoex was the most abundant, followed by B. Stearothermophilus, B. Sphericus, B. licheniformis and B, brevis.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.4
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• pp.104-112
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• 2006

Population growths of earthworm were investigated when the earthworm populations with different levels of initial densities per unit area were fed with cow dung mixed with paper mill sludge. The tested levels of earthworm densities were as follows; $1kg/m^2$, $2kg/m^2$, $3kg/m^2$, $5kg/m^2$. There were no significant differences in population growth rates 60 and 90 days after feed supply among the tested densities of earthworm. Therefore, it was suggested that initial densities of earthworm populations per unit area higher than $3kg/m^2$ should not be favorable because of the cost for purchasing earthworm. Vermicomposting rates of earthworm on feed were also investigated when different amounts of feed were supplied repeatedly to unit area of nursery bed with $5kg/m^2$ of initial densities earthworm populations. The tested amounts of feed at each supplying time were as follows; $16kg/m^2$, $24kg/m^2$, $32kg/m^2$, $40kg/m^2$. The more the amount of feed at each supplying time, the higher vermicomposting rate and population growth rate. Therefore, it should be more favorable for earthworm breeders to supply more than $40kg/m^2$ of feed at each supplying time, because it would reduce time and labor cost.

• Korea journal of population studies
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• v.28 no.2
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• pp.219-243
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• 2005

This paper reviews research outputs in Korea Journal of Population Studies (KJPS) and the changes in their contents during the period of 1977-2004. In the early years of KJPS, various types of outputs were published, but changes have been made into a direction that research articles compose the main context of the journal. As the journal published twice a year, the total number of articles of the journal shows a trend of marked rise. An analysis of the themes of articles shows that the trend of research in Korean demography has changed hand in hand with transformations of the Korean society. The traditional topics such as population policy, fertility, mortality, and migration were popular before. Labor force, nuptiality, family, aging, regional studies are found to be more popular themes of research recently. Reflecting academic and social demands, KJPS has a broaden range of authors, such as professor, researcher, a government employee, post-doc, and graduate students. The articles written by those working in universities have increased continuously, while research outputs of research institutes have decreased recently. The data for analysis used in articles are varied from but concentrated in some materials - census, vital statistics and various survey data. In early years of KJPS, relatively simple techniques of analysis were adopted in the majority of articles. However, more sophisticated techniques including applied regression analysis, logistic analysis and analysis of survival ratio turn out to be more popular recently. Finally, several suggestions for the future research are presented in this paper.

• Journal of the Economic Geographical Society of Korea
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• v.24 no.4
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• pp.411-424
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• 2021

The purpose of this study is to analyze the location characteristics of convenience stores, a consumption industry that forms a new retail environment and implements unattended, and reveals the geographic factors that affect its location. For this purpose, we first examine the growth and regional distribution of manned convenience stores and then construct a gamma generalized linear regression model that explains the distribution of the unmanned convenience stores as well as the manned and unmanned combined convenience stores. As the result, it was observed that the unmanned convenience stores and the unmanned discount stores are located close to public transportation facilities and they have relatively little movement of the population but they are distributed in areas with a higher density of young residential population and densely distributed retail stores and restaurants. The effects of demographic factors on the location of the unmanned convenience stores and the unmanned discount stores differed according to the scope and characteristics of their sales items. Our findings provide an empirical basis for subsequent academic research as an initial study that identified geographic factors influencing the selection of opening locations for unmanned stores.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1B
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• pp.27-32
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• 2003

This paper presents the Genetic Algorithm based Task Scheduling (GATS) method for the scheduling of programs with diverse embedded parallelism types in Distributed Parallel Systems, which consist of a set of loosely coupled parallel and vector machines connected via high speed networks The distributed parallel processing tries to solve computationally intensive problems that have several types of parallelism, on a suite of high performance and parallel machines in a manner that best utilizes the capabilities of each machine. When scheduling in distributed parallel systems, the matching of the parallelism characteristics between tasks and parallel machines rather than load balancing should be carefully handled with the minimization of communication cost in order to obtain more speedup. This paper proposes the based initialization methods for an initial population and the knowledge-based mutation methods to accommodate the parallelism type matching in genetic algorithms.

• Research in Plant Disease
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• v.18 no.4
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• pp.361-369
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• 2012

A population density model for bacterial wilt, which is caused by Ralstonia solanacearum, in hot pepper was developed to estimate the primary infection date after overwintering in the field. We developed the model mechansitically to predict reproduction of the pathogen and pathogensis on seedlings of the host. The model estimates the pathogen's populations both in the soil and in the host. In order to quantify environmental infection factors, various temperatures and initial population densities were determined for wilt symptoms on the seedlings of hot pepper in a chamber. Once, the pathogens living in soil multiply up to 400 cells/g of soil, they can infect successfully in the host. Primary infection in a host was supposed to be started when the population of the pathogen were over $10^9$ cells/g of root tissue. The estimated primary infection dates of bacterial wilt in 2011 in Korea were mostly mid-July or late-July which were 10-15 days earlier than those in 2010. Two kinds of meterological data, synoptic observation and field measurements from paddy field and orchard in Kyunggi, were operated the model for comparing the result dates. About 1-3 days were earlier from field data than from synoptic observation.

• Journal of Applied Biological Chemistry
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• v.62 no.2
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• pp.181-186
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• 2019

The optimum design of LED device for irradiation of 460 nm blue light on extruded rice cake using simulation and the effect of the blue light on the inactivation of Bacillus cereus (B. cereus) group on the rice cake were investigated. The irradiated light intensity patterns on the surface area of the sample were simulated with three different LED arrays (centered, cross, and evenly spaced) and at various distances (22, 32, 42 mm) between the LED modules and the sample. In addition, the uniformity was calculated as Petri factor. The evenly spaced array resulted the most uniform light intensity pattern in the simulation, and the Petri factor of 32 and 42 mm of the distances showed higher than 0.9, which represents the ideal uniformity of LED device. The bacterial population of the rice cake decreased to less than the initial bacterial population during exposure to LED blue light, whereas the bacterial population of the control sample increased. The bacterial count of the rice cake after blue light irradiation for 24 h was 1.21 log CFU/g lower than the control sample. Petri factor increased with increase of the distance between the light source and sample, however, the reduction rate of B. cereus group decreased. Therefore, the design of LED device, that represented the Petri factor higher than 0.9 and inactivated the population of B. cereus group, with evenly spaced and 32 mm of distance between the light source and sample was suitable for extending shelf-life of rice cake.

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.27-35
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• 2021

Artificial life is used in various fields of applied science by evaluating natural life-related systems, their processes, and evolution. Research has been actively conducted to evolve physical body design and behavioral control strategies for the dynamic activities of these artificial life forms. However, since co-evolution of shapes and neural networks is difficult, artificial life with optimized movements has only one movement in one form and most do not consider the environmental conditions around it. In this paper, artificial life that co-evolve bodies and neural networks using predator-prey models have environmental adaptive movements. The predator-prey hierarchy is then extended to the top-level predator, medium predator, prey three stages to determine the stability of the simulation according to initial population density and correlate between body evolution and population dynamics.