• Journal of Aquaculture
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• v.21 no.1
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• pp.47-53
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• 2008

The purpose of this study was to suggest that selecting method of rotifer with high activity of digestive enzymes for the enrichment effect of rotifer and the increasing of digestive enzymes of fish larvae. the populations assayed the activities of the digestive enzymes were randomly selected out of several population communities cultured with freshwater condensed Chlorella. The relationship with the population density and the growth rate of selected populations was shown to RD=5865 SGR-350.08(P<0.001). The relationships with fecundity of the growth rate and the population density were shown to F=-36.147 SGR+61.652(P<0.05) and F=-0.0085 RD+66.38(P<0.001), respectively. The relationships of the growth rate and the individual activities of digestive enzymes in rotifer were assayed to Amyl=-1.6482 SGR+3.2498(P<0.05), TAP=-0.8115 SGR+1.1361(P<0.001) and TGL+0.0055 SGR+0.0079(P=0.239), respectively. But in TG-lipase was not related significantly with the growth rate. Also the relationships of the fecundity and the individual activities of digestive enzymes in rotifer were shown to Amyl=0.0296 F+1.0981(P<0.001), TAP=0.0252 F+0.0975(P<0.001) and TGL=-6E-06 F+0.0113(P=0.915), respectively. But in TG-lipase was not related significantly with the fecundity. And the relationships with the specific activity of TG-lipase of the fecundity, the growth rate and the population density were TGL=-0.024 F+0.2332(P=0.132), TGL=0.1267 SGR+0.005(P<0.01) and TGL=0.0002 F-0.0594(P<0.001), respectively. In this case, specific activity of TG-lipase was shown the significant relationship with the population density and the growth rate, but it was not related significantly with fecundity. Therefore, Because a population shown the high activity of digestive enzymes for increasing a lipid enrichment effect of a rotifers and receiving the many exogenous digestive enzymes to fish larvae was the population of high fecundity than the population of high rotifer density, to select the population of a high fecundity was suggested to benefit than a high growth rate for fish larvae.

• The Korean Journal of Ecology
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• v.17 no.4
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• pp.453-461
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• 1994

Size class structure and vegetative growth of a perennial herb of the temperate deciduous forests, Symplocarpus renifolius Schott, were studied from 1991 to 1994 in Namhansansung, Kyonggi Province, Korea. The size class structures of leaf number and leaf area per individual followed bell-shape curve, i.e. frequency of middle class was relatively high. The leaf area increased from the late-March to mid-May. At the end of the growing season, leaf area(length X breadth) was proportional to biomass, especially aboveground biomass. The leaf number and leaf area per individual increased at the rate of 0.08 leaf/year and 9.7 $cm^2/year$, respectively. The size of the individuals in large-sized classes, in leaf number and leaf area, decreased in next year, while the size of the individuals in small-sized classes increased. Therefore, it was concluded that the size class structure of S. renifolius population was largely determined by the growth form.

• Management Science and Financial Engineering
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• v.16 no.3
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• pp.49-70
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• 2010

Customer population management models can be classified into three categories: the first category includes the models that analyze the customer population at cohort level; the second one deals with the customer population at aggregate level; the third one has interest in the interactions among the customer populations in the competitive market. Our study proposes a model that can analyze the dynamics of customer population in consumer-durables market at aggregate level. The dynamics of customer population includes the retention curves from the purchase or at a specific duration time, the duration time expectancy at a specific duration time, and customer population growth or decline including net replacement rate, intrinsic rate of increase, and the generation time of customer population. For this study, we adopt mathematical ecology models, redefine them, and restructure interdisciplinary models to analyze the dynamics of customer population at aggregate level. We use the data of previous research on dynamic customer population management at cohort level to compare its results with those of ours and to demonstrate the useful analytical effects which the precious research cannot provide for marketers.

• Korean Journal of Environment and Ecology
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• v.27 no.4
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• pp.417-428
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• 2013

The red fox (Vulpes vulpes), listed as a Class I endangered species by the Ministry of Environment of Korea, has been considered to be extinct in South Korea since the 1980s, and an intensive restoration project has been underway in Sobaeksan national park. This study was carried out to develop a suitable model for the red fox reintroduction program based on Population viability analysis (PVA) by using the VORTEX program. If 10 animals (5 females and 5 males) were continuously released into the initial zero population every year for 10 years, population growth rate and extinction probability over the next 50 years after the introduction of the population were $0.018{\pm}0.204$ and 0.354, respectively; the maximum population size was 116.34 at the 16th year after the first release, and a reduction rate of 1.22 every year from the 17th year was inferred. We found that additional releases would be needed from the 17th year after the initial release to maintain a positive growth rate and to prevent the extinction of the released red foxes, and releasing more than 12 individuals every year would be needed for the long-term, continuous existence of red foxes. By contrast, if fewer than 6 red fox individuals were released the extinction probability over the next 50 years was more than 80%. To maintain the minimum population growth rate, the release of more than 8 individuals were needed for positive population growth. The population growth rate was more stable when 10 animals in the change of their sex rate every year from the set value were released as the female-to- male sex ratio of 6:4 rather than 1:1. However, if the female-biased sex ratio was increased by more than 7:3, a negative population growth was expected. The occurrence rate of roadkill and poaching are important factors in the red fox restoration project. The extinction probability was decreased to 30% if each factor was decreased to 3% based on the standard baseline; however, if each factor was increased to more than 3%, an extinction rate of about 90% was reached over the next 50 years.

• Korea journal of population studies
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• v.28 no.2
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• pp.1-32
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• 2005

The optimum population of a society or country can be defined as 'the population growth path that maximizes the welfare level of the society over the whole generations of both the present and the future, under the paths allowed by its endowments of production factors such as technology, capital and labor'. Thus, the optimum size or growth rate of population depends on: (i) the social welfare function, (ii) the production function, and (iii)demographic economic interrelationship which defines how the national income is disposed into consumption(birth and education of children included) and savings on the one hand and how the demographic and economic change induced thereby, in turn, affect production capacities on the other. The optimum population growth path can, then, be derived in the process of dynamic optimization of (i) under the constraints of (ii) and (iii), which will give us the optimum population growth rate defined as a function of parameters thereof. This paper estimates the optimum population growth rate of Korea by: specifying (i), (ii), and (iii) based on the recent development of economic theories, solving the dynamic optimization problem and inserting empirical estimates in Korea as the parametric values. The result shows that the optimum path of population growth in Korea is around TFR=1.81, which is affected most sensitively, in terms of the size of the partial elasticity around the optimum path, by the cost of children, share of capital income, consumption rate, time preference, population elasticity of utility function, etc. According to a survey implemented as a follow up study, there are quite a significant variations in the perceived cost of children, time preference rate, population elasticity of utility across different socio-economic classes in Korea, which implied that, compared to their counterparts, older generation and more highly educated classes prefer higher growth path for the population of Korea.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.359-374
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• 2012

This paper intends to examine spatial patterns and regional variations of aging population in Korea based on census data for 163 areas during 1980~2010. It briefly investigates general characteristics of aging population in Korea from previous studies and clarifies spatial patterns of aging process at regional level with reference of population growth rate at different time periods. Cities in Korea are classified into several stages including aging society, aged society and super-aged society according to the percentages of aging population out of total population every five years. At the regional scale, the stage of aging society was revealed from 1980, while the stage of aged society was shown from 1995 and super-aged society was entered from 2000 in Korea. Eighty cities in the analysis were shown at the stage of super-aged society in 2010. The portions of aging population are highly related to city size and population growth rate. For instance, the cities both in small size and with low population growth rate are revealing high percentage of aging population. As of 2010, most rural areas are staged into super-aged society, while most cities within Seoul metropolitan area and mid-sized cities are kept in the stage of aging society. At regional scale, there are no significant statistical correlations between total fertility rate and aging population.

• East Asian Journal of Business Economics (EAJBE)
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• v.2 no.2
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• pp.58-67
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• 2014

If we compare the GDP per Capita for the last 20 years between Philippines and other ASEAN countries, Philippines remains in the lowest on GDP per Capita. This paper is trying to find out the possible reasons for the low growth rate of the GDP per Capita in the Philippines. 53 years data from the World Bank are used explore the relationships between the GDP per Capita and eight economic indicators to run three time series models and one to one regression. Three indicators, namely, consumer price index, gross capital formation as a percentage of GDP and population are remarked with possible contribution to the low growth rate of the GDP per capita of the Philippines.

• Korean Journal of Mathematics
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• v.13 no.2
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• pp.161-176
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• 2005

We consider a model of population dynamics whose mortality function is unbounded. We note that the regularity of the solution depends on the growth rate of the mortality near the maximum age. We propose Gauss-Legendre methods along the characteristics to approximate the solution when the solution is smooth enough. It is proven that the scheme is convergent at fourth-order rate in the maximum norm. We also propose discontinuous Galerkin finite element methods to approximate the solution which is not smooth enough. The stability of the method is discussed. Several numerical examples are presented.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.664-671
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• 2006

Modeling the growth kinetics of lactic acid bacteria (LAB), one of the most valuable microbial groups in the food industry, has been actively pursued in order to understand, control, and optimize the relevant fermentation processes. Most modeling approaches have focused on the development of single population models. Primary single population models provide fundamental kinetic information on the proliferation of a primary LAB species, the effects of biological factors on cell inhibition, and the metabolic reactions associated with cell growth. Secondary single population models can evaluate the dependence of primary model parameters, such as the maximum specific growth rate of LAB, on the initial external environmental conditions. This review elucidates some of the most important single population models that are conveniently applicable to the LAB fermentation analyses. Also, a well-defined mixed population model is presented as a valuable tool for assessing potential microbial interactions during fermentation with multiple LAB species.

• Journal of the Society of Disaster Information
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• v.16 no.3
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• pp.479-492
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• 2020

Purpose: The purpose of this study is to analyze the impact of regional characteristics on population movement on the Seoul metropolitan areas. Method: To this end, 66 basic entities in the Seoul metropolitan area were divided into three regions by analyzing the demographic movement data from 2010 to 2016 and the factors for determining population movement within and between regions were identified by applying a stepwise regression technique. Result: The major analysis confirmed that the increase in the number of apartments in all areas of the Seoul metropolitan area, the increase in the number of single-family homes, the increase in the number of employees, the increase in manufacturers, the growth rate of knowledge, culture, and leisure industries, the increase rate of GRDP, and the opening of new subway stations. In particular, the growth rate of the number of apartments, the growth rate of the knowledge, culture and leisure industries, the increase rate of GRDP, and the opening of new subway stations played a positive role in increasing population inflow. Conclusion: The result showed that by region, the growth rate of knowledge, culture and leisure industries contributed greatly to the inflow of population in the first region, and that the opening of new subway stations and the increase of GRDPs were the main factors. The increase in the number of apartments and subway stations were the main factors in the three areas.