• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.12
• /
• pp.1680-1686
• /
• 1995

GAs, effective stochastic search algorithms based on the model of natural evolution and genetics, have been successfully applied to various optimization problems. When population size is not large, GAs often suffer from the phenomenon of premature convergence in which all chromosomes in the population lose the diversity of genes before they find the optimal solution. In this paper, we propose that a new heuristic that maintains the diversity of genes by adding some chromosomes with random mutation and selective mutation into population during evolution. And population size changes dynamically with supplement of new chromosomes. Experimental results for several test functions show that when population size is rather small and the length of chromosome is not long, this method is effective.

• Korean Journal of Organic Agriculture
• /
• v.15 no.3
• /
• pp.291-307
• /
• 2007

The objective of this article is to examine the structure of the composition of the population in rural area for the last 45 years, and to forecast mid and long term structure of the population in the near future. Moreover, forecast has been done whether the rapid increase by the inflow of foreigners has any offset on the structural change in rural population. According to the research result, the rural area is experiencing a rapid decrease in population, a rapid increase in the percentage of the aged, and foreigners. To resolve the problematic situation mentioned above, some effective counterplan has to be considered by all agencies concerned.

• KDI Journal of Economic Policy
• /
• v.45 no.2
• /
• pp.51-69
• /
• 2023

Korea's population is aging at a faster pace than any other major country, and the adverse impact of this trend on the economy is predicted to be significant. This paper focuses on the macroeconomic effects of population aging with particular attention paid to the pace of aging in Korea. According to our analysis, it is difficult to offset the decline in the labor supply driven by rapid population aging, even if the labor force participation rate of the working-age population rises to a significantly high level. We suggest a re-orientation of policy directions to correspond to the behavioral changes of economic agents. Policies must focus on promoting labor force participation among the elderly while pushing towards human capital advancement and higher productivity.

• Journal of Korean Home Economics Education Association
• /
• v.26 no.4
• /
• pp.147-164
• /
• 2014

This study aimed to explore the effects of population education on university male female students' recognition of population education and low fertility and aged society. The subjects were 71 university students(male: 36, female: 35) participating in population education program. The data were analyzed with descriptive statistics, paired t test and two-way ANOVA with repeated measures. The main results of this study were as follows. Firstly, population education led to positive changes in university students' recognition of population education and of low fertility and aged society. Specifically, after taking the population education courses, students' levels of knowledge on population education contents and on foreign domestic policies related to low fertility and aged society increased. Secondly, there were students' sex differences in the effect of population education on recognition of population education and low fertility and aged society. For only female students, there were significantly positive changes in realization of the seriousness of low fertility and aged society, in recognition of importance of population education, work-family reconciliation and child-care centers to solve the issues of low fertility and aged societies, in knowledge levels of foreign domestic policies related to low fertility and aged society, and in awareness of family of small members(ex. single families). Finally, based on the results, the roles of Home Economics Education were suggested in population education.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.26 no.4
• /
• pp.97-115
• /
• 2023

In recent years, the structure of the population has been changing rapidly, with a declining birthrate and aging population, and the inequality of population distribution is expanding. At this point, changes in population estimation methods are required, and more accurate estimates are needed at the subregional level. This study aims to estimate the population in 2040 at the 500m grid level by applying an explainable machine learning to Busan in order to respond to this need for a change in population estimation method. Comparing the results of population estimation by applying the explainable machine learning and the cohort component method, we found that the machine learning produces lower errors and is more applicable to estimating areas with large population changes. This is because machine learning can account for a combination of variables that are likely to affect demographic change. Overestimated population values in a declining population period are likely to cause problems in urban planning, such as inefficiency of investment and overinvestment in certain sectors, resulting in a decrease in quality in other sectors. Underestimated population values can also accelerate the shrinkage of cities and reduce the quality of life, so there is a need to develop appropriate population estimation methods and alternatives.

• Plant Disease and Agriculture
• /
• v.5 no.1
• /
• pp.41-45
• /
• 1999

Bacterial population densities on soybean pods from Chungnam province ranges 105~106 CFU/$\textrm{cm}^2$, whereas those of bacteria causing sprout rot ranged 0~103 CFU/$\textrm{cm}^2$. Erwinia chrysanthemi, Xanthomonas campestris pv. glycines, Staphylococcus sp., and Micrococcus sp. were identified as pathogenic bacteria causing soybean sprout rot. The population density of X. campestris pv. glycines was higher than those of other bacteria.

• Journal of Ecology and Environment
• /
• v.33 no.4
• /
• pp.317-323
• /
• 2010

Nutrient availability is a critical component of agroecosystems, and is relevant to both above- and below- ground interactions. The principal objective of this study was to determine how the cessation of fertilization affects the communities of weeds and soil organisms in a corn/wheat field. Changes in dominant weed species, substrate-induced respiration, and the population density of nematodes and microarthropods were evaluated. Microbial substrate-induced respiration (SIR) and the population density of microarthropods decreased following the cessation of fertilization and were partly correlated with the aboveground weed biomass. The cessation of organic fertilizer application but continuing application of inorganic fertilizer reduced the population density of nematodes. In response to the cessation of fertilization, weed communities were dominated by species with little dependency on fertilization. Amaranthus retroflexus was identified as the most dominant species in the corn field; however, it was replaced by Digitaria ciliaris after the cessation of fertilization. In the wheat field, the cessation of fertilization led to a rapid reduction in the biomass of most weeds, except for Vicia angustifolia, supposedly as the result of symbiotic nitrogen fixation. Additionally, the fact that weed biomass was partially correlated with SIR or the population density of microarthropods may reflect a mutual feedback between soil organisms and weeds. The results indicate that the cessation of fertilization alters communities of weeds and soil organisms through changes in weed biomass and interactions with symbiotic microorganisms.

• Journal of Environmental Health Sciences
• /
• v.49 no.6
• /
• pp.362-371
• /
• 2023

Background: PM_2.5 pollution has been a persistent problem in South Korea, with concentrations consistently exceeding World Health Organization (WHO) guidelines. The aging of the population in the country further exacerbates the health impacts of PM_2.5 since older adults are more susceptible to the adverse effects of air pollution. Objectives: This study aims to evaluate how the health impact (premature death) due to long-term exposure to PM_2.5 in South Korea could change in the future according to the trend of change in the country's population structure. Methods: The study employs a relative risk function, which accounts for age-specific relative risks, to assess the changes in premature deaths by age and region at the average annual PM_2.5 concentration for 2022 and at PM_2.5 concentration improvement levels. Premature deaths were estimated using the Global Exposure Mortality Model (GEMM). Results: The findings indicate that the increase in premature deaths resulting from the projected population structure changes up to 2050 would significantly outweigh the health benefits (reduction in premature deaths) compared to 2012. This is primarily attributed to the rising number of premature deaths among the elderly due to population aging. Furthermore, the study suggests that the effectiveness of the current domestic PM_2.5 standard would be halved by 2050 due to the increasing impact of population aging on PM_2.5-related mortality. Conclusions: The study highlights the importance of considering trends in population structure when evaluating the health benefits of air pollution reduction measures. By comparing and evaluating the health benefits in reflection of changes in population structure to the predicted PM_2.5 concentration improvements at the provincial level, a more comprehensive assessment of regional air quality management strategies can be achieved.

• Journal of Agricultural Extension & Community Development
• /
• v.12 no.1
• /
• pp.17-28
• /
• 2005

This study investigated structural changes of the Korea's agriculture and proposed the new direction of rural and agricultural policy in Korea after economic opening. The major results may be summarized as follows: Firstly, the study identified structural changes of the country's peasantry under the economic opening system. Korean agriculture has been deteriorated in population structure, arable land size, and income composition. Secondly, according to above analysis on these changes it suggested that the traditional rural communities were exposed to collapse and this unwanted disaster could result in serious adversities to the national economy. Thirdly, this study proposed preservation policies for small scale farming households and also administrative preparations of multi-dimensional approaches leading to successful rural and agricultural planning.

• Asian Journal of Business Environment
• /
• v.9 no.4
• /
• pp.23-28
• /
• 2019

Purpose - With rapid population aging in Korea, changes in the population structure will result in a rise in the fiscal burden. This paper investigates the effects of population aging on fiscal spending based on Korea's province data and country panel data from the OECD. Research design, data, and methodology - We use province-level fiscal data from Local Finance Integrated Open System and the Korean Statistical Information Service and also collect country panel data from the OECD. To investigate the relationship between population aging and fiscal expenditures, our analysis uses the fixed effects model. Results - The empirical analysis based on Korean local finance and country panel data show that population aging has a positive impact on social welfare expenditures and it also has a positive impact on spending related to children and the elderly, implying that population aging may lead to an increase in fiscal spending via an increase in social welfare expenditures and spending related to children and the elderly. Conclusion - These empirical results suggest that countries like Korea that expect to experience rapid population aging need to pay more attention to prepare for the expected increase in age-related spending in the near future.