• 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.

• Korea journal of population studies
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• v.14 no.2
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• pp.1-17
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• 1991

While various fiscal measures have been used to influence regional capital inflow or industrial location, the effect of fiscal variables on labor mobility has been little understood. Understanding the relationship between the composition of local public and urban migration would enhance the city govenment's ability to pursue an appropriate population policy. In order to examine the potential for local public finance to be utilized as a policy tool in directing urban population growth, this paper analyzes the impact of local government financial structure on urban migration. In examining the data on local government finance and the changes in population of Korean cities during the last ten years, it was found that cities with high per capita expenditure in regional development have experienced high population growth rates. In this study migration equations were constructed using various fiscal variables such as the proportion of special account expenditures which are mostly spent for local development purposes, per capita regional development expenditure, degree of local financial independence and per capita net fiscal benefit, along with other explanatory variables. The results of regression analysis showed that city government's regional development expenditure variables have a positive effect on urban net migration and a negative effect on outmigration. Fiscal independence and per capita net fiscal benefit had mixed effects on in and out migration variables, implying that local tax burden does not consistently deter inmigration or induce outmigration. Based on the results of this study some important policy implications can be found regarding local government's fiscal policies. Those cities seeking to attract higher population inflow should make a greater effort in appropriating local expenditures for regional development purposes such as infrastructure, housing, and transportation. city governments should not be too concerned about high local tax burden or necessarily seek to enhance financial independence for these factors do not exert a clear influence on urban population growth or labor supply.

• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1185-1202
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• 2010

In this paper, we have studied the dynamical behaviour such as boundedness, local and global stabilities, bifurcation of a single species population affected by environmental toxicant and population toxicant. We have also studied the effect of discrete delay of the environmental toxicant on the instantaneous growth rates of the population biomass and population toxicant due to incubation period. The length of delay preserving the stability is also estimated. Computer simulations are carried out to illustrate our analytical findings.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.227-234
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• 2010

A comparative analysis of size and age structures of coastal subfossil shell assemblages of the shortnecked clam Ruditapes philippinarum from open and protected bays of Cheju Island (Korea) was carried out. On the whole, taking into account the damage of small fragile shells, size and age structures of the shell assemblages corresponded to the classical curve of bivalve population distribution when its mortality diminishes with age increase up to a certain threshold. It was found that shell samples from open bays of the western, southern and eastern coasts included shells of smaller and younger individuals (L ${\leq}$ 40 mm, ${\leq}$ 4 years) than samples from the eastern protected bay (L ${\leq}$ 54.5 mm, ${\leq}$ 6 years). Evidently, strong wave activity was the reason for a short life-span of the clams from the open areas. Growth was investigated retrospectively by annual growth rings on the shells. Growth rates of the clams from the various coasts of Cheju Island differed. However, growth rates of the clams from different biotopes at the same (eastern) side of the Island were similar. Shell height/length and width/length ratios statistically significantly increased with the clam age increase. Most likely, the reason for such shell shape alteration is that more conglobated individuals more survive being more energy-optimal than oblong specimens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.144-150
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• 2003

Reproductive biology and population dynamics of Latreutes planirostris were investigated on the south western waters of Korea from June 2001 to May 2002. This paper describes sex ratio, population growth, and reproductive aspects of Latreutes planirostris. Brood size was an isometric function of female carapace length. Based on dry weight, reproduction effort (mass of eggs/mass of female) averaged 0.23. Ovarian examination showed that there was significantly higher gonadosomatic index from May to September, with a peak in June. Statistical analysis revealed that the ovarian dry weight of females with eyed eggs was significantly higher than that of those with non-eyed eggs. This suggests that females were potentially consecutive breeders. Sex ratio showed that female is more numerous than male. Growth parameters mortality and recruitment were estimated by monthly length-frequency data. Growth parameters were estimated, using the seasonalized von Bertalanffy growth function model $(L\infty\;=\;12.70\;mm\;CL,\;K\;=\;0.87yr^{-1},\;C\;=\;0.96,\;WP\;=\;0.59)$. The recruitment pattern was twice a year.

• Journal of Plant Biology
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• v.20 no.3
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• pp.119-126
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• 1977

The maximum relative growth rate of algae treated with Zinc was shown as follows: 15, 8, 6, 3 and -5% per day for the rather sensitive Chlorella sp. populations, or 14, 7, 5 and 4% per day for the Pleurococcus sp. populations, and 22, 20, 13, 9 and 7% per day for the more resistant Scenedesmus spinosus populations, respectively for the culture medium with 0, 1, 5, 10 and 20 ppm of Zinc treatment. With mixed cultures of Chlorella sp. and Scenedesmus spinosus populations, the growth of the Chlorella sp. population overcame that of the S. spinomsus population from the cultures treated with relatively low concentration of Zinc. On the contrary, the population growth of the latter resistant species overcame that of the former sensitive species when the concentration of Zinc was above 5 ppm Zn of the medium. This paper describes the results of further investigations of the effects evaluated by direct cell counts method, optical density comparisons, oxygen production and consumption determinations and the measurements of the fate of Zinc treated in the solutions.

• Journal of the Korean housing association
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• v.21 no.4
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• pp.11-22
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• 2010

In the urban area where rapid suburbanization trend continues, the role of mixed use building is controversial. It is argued that the mixed use building is an effective tool to recover residential function of urban core(urban regeneration). It is also argued that the building is a cause of serious urban problems, such as congestion, public service shortages. The fundamental purpose of this study is to examine the role of mixed use building in terms of urban growth management in Seoul. For this purpose, data of mixed use building from 1981 to 2007 are collected and analysed. The results show that most of mixed use buildings are located in either sub-centers or population losing areas, rather than traditional urban core. Therefore, it is hard to accept that the two controversial arguments. The mixed use building noncore areas in most cases. However, it dose help to increase population inflow in non-core areas. it is difficult to accept the public service assertion which states that super-high rise mixed use building causes public service congestion, because the building is built in population losing or demand decreasing area. Based on these findings this study suggests some policy alternatives such as urban service boundary or concurrency program to management urban growth.

• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.30-36
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• 2018

This study investigates the relationship between economic growth, energy consumption, trade openness, population density, and carbon dioxide ($CO_2$) emissions in Bangladesh for the period of 1975 to 2013. It applies the Autoregressive Distributed Lag (ARDL) bounds testing approach to cointegration for establishing the existence of a long-run relationship. The bounds tests suggest that the variables of interest are bound together in the long-run when $CO_2$ emissions is the dependent variable. The results indicate that energy consumption has statistically significant positive effect on $CO_2$ emissions both in the short-run and long-run. The effect of population density is significant in long-run, but not in short-run. The estimated coefficients for economic growth and trade liberalization are negative and insignificant both in short-run and long-run. The paper suggests that the government of Bangladesh should undertake the policy actions to develop alternative energy sources which would not emit much $CO_2$.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.9
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• pp.1369-1377
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• 2020

Objective: The main objectives of the present study were to assess the genetic diversity, population structure and to appraise the efficiency of ongoing selective breeding program in the closed nucleus herd of Nellore sheep through pedigree analysis. Methods: Information utilized in the study was collected from the pedigree records of Livestock Research Station, Palamaner during the period from 1989 to 2016. Genealogical parameters like generation interval, pedigree completeness, inbreeding level, average relatedness among the animals and genetic conservation index were estimated based on gene origin probabilities. Lambs born during 2012 and 2016 were considered as reference population. Two animal models either with the use of F_i or ΔF_i as linear co-variables were evaluated to know the effects of inbreeding on the growth traits of Nellore sheep. Results: Average generation interval and realized effective population size for the reference cohort were estimated as 3.38±0.10 and 91.56±1.58, respectively and the average inbreeding coefficient for reference population was 3.32%. Similarly, the effective number of founders, ancestors and founder genome equivalent of the reference population were observed as 47, 37, and 22.48, respectively. Fifty per cent of the genetic variability was explained by 14 influential ancestors in the reference cohort. The ratio f_e/f_a obtained in the study was 1.21, which is an indicator of bottlenecks in the population. The number of equivalent generations obtained in the study was 4.23 and this estimate suggested the fair depth of the pedigree. Conclusion: Study suggested that the population had decent levels of genetic diversity and a non-significant influence of inbreeding coefficient on growth traits of Nellore lambs. However, small portion of genetic diversity was lost due to a disproportionate contribution of founders and bottlenecks. Hence, breeding strategies which improve the genetic gain, widens the selection process and with optimum levels of inbreeding are recommended for the herd.

• Journal of Animal Environmental Science
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• v.1 no.1
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• pp.65-75
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• 1995

This experiment was carried out to the effects of population density and C/N ratios of feed on the growth, reproductive effciency and cast producation of the earthworm(Eisenia foetida). The population densities of 50, 100, 150, 200 and 250 individuals of the earthworm fed with different C/N ratios of 25, 35, 45 and 55 cow manures were studied in rearing box($6,400cm^3$), and at the fertility stage during a period of 60 days. The results were summarized as follows; The survial rate(SR), increasing rate(IR), reproductive efficiency(RE) and cast production of the earthworms showed highest values in C/N ratio of 25. These results may indicate that C/N ratio of 25 is a very favourable feed for the growth of the earthworms. The survial rate(SR) indicated significant positive correlation with reproductive efficiency(RE) in different C/N ratios of feeds. The survial rate(SR) showed highest values in population densities of $50{\sim}100$ worms/$6,400cm^3(64.0{\sim}128.0cm^3/worm$). On the contrary, increasing rate(IR) tended to decreased with the increased population densities. The survival rate(SR) indicated significant negative correlation with reproductive efficiency(RE) in different population densities of the earthworms. The cast production estimated were $31.6mg{\sim}67.4mg/day/worm$ grown in optimum population densities($50{\sim}100\;worms/6,400cm^3$). The earthworm casting are an excellent soil conditioning material or organic fertilizer sources with a high chemical composition and their physical properties.