• Journal of Ecology and Environment
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• v.38 no.1
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• pp.39-45
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• 2015

In this study, the dependence of local conspecific abundance on seed set and predation was examined, and determinates of population density of the temperate tree species Carpinus laxiflora (Betulaceae) in Inagi city, Tokyo, Japan were identified. During a good seed year (2013), seeds were sampled from 27 individuals and categorized as Sound, Empty, Predated, Immature, Decayed, or Broken. Empty seeds were identified as those that failed to fertilize and predation rates were defined as the proportion of seeds that were affected by predators. The proportion of the seed set that was fertilized was significantly positively correlated with local abundance of conspecific trees, while the proportion of seeds that escaped predation was significantly negatively correlated with local abundance of conspecific trees. Thereby, the production of Sound seeds was highest at sites with moderate local conspecific abundance. Although this phenomenon was only observed in a few cases, it clearly showed optimal reproductive success under conditions of moderate density of conspecific reproductive adults, suggesting a mechanism that controls the population density of this species.

• Journal of the Korean Statistical Society
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• v.36 no.2
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• pp.275-284
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• 2007

Confidence intervals for the population proportion in a double sampling scheme subject to false-positive misclassification are considered. The confidence intervals are obtained by applying Agresti and Coull's approach, so-called "adding two-failures and two successes". They are compared in terms of coverage probabilities and expected widths with the Wald interval and the confidence interval given by Boese et al. (2006). The latter one is a test-based confidence interval and is known to have good properties. It is shown that the Agresti and Coull's approach provides a relatively simple but effective confidence interval.

• Journal of the Korean Geographical Society
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• v.49 no.5
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• pp.747-760
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• 2014

This study presents the extent of disparity of human capital across regions, its trend, and the impact of aging on it, using Korean census data of years 1985, 1995, and 2005. Main results are as follows. First, the absolute level of human capital in cities and districts have increased, but the relative positions of those regions have not changed over time. Second, the proportion of college graduated tends to increase as the size of cities increases. Third, following Berry and Glaeser(2005), the increase in the proportion of college graduated is regressed on the initial proportion and the estimates indicate that the disparity of human capital across regions has increased over time. Fourth, the proportion of aging population is shown to have a negative relationship with the proportion of college graduated. Finally, using a counter-factual scenario that there were no differences in proportions of aging population across regions, it is shown that the disparity of human capital across regions could be reduced substantially.

• Korea journal of population studies
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• v.29 no.1
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• pp.241-268
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• 2006

This study aim to examine the optimum population in Korea, which has the lowest fertility rate in the world. This study has significance because this rapid decline in the fertility rate is expected to bring the decrease of the population and unbalance in the population composition in Korea. From the social welfare perspective, the optimum population is guided by maximization of the social welfare level per person or the social welfare level in a society. The optimum population can be defined as follows: The proportion of older adults 65 and over is 15-17%, the proportion of work force is 64-69%, the index of aging is 72-104. Within the current population and population composition, the optimum population is estimated as 4.85-4.95 million. These findings imply that we need to remove causes of low fertility rate and prepare for policies encouraging immigration of labor force from foreign countries. In addition, policies and programs where children can be grown up in good environments and women and older adults can participate in labor force should be established.

• Korean Journal of Community Nutrition
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• v.11 no.6
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• pp.808-813
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• 2006

Until now, South Korea does not have either fortification or enrichment program as intervention tools although the addition of micronutrients to foods is for the most part not regulated. The aim of this study was to determine which scenario would most effectively reduce the proportion of the population with low iron intake while not putting other population groups at risk of excessive intakes. In order to investigate potential dietary consequences of iron fortification we analyzed 2 day dietary record data (n=3,955) from the 2001 National Nutrition Surveys. The Proportion of the population consuming dietary iron less than the estimated average requirement (EAR) ranged from $12.4{\sim}87.5%$ depending upon gender and age group. Iron fortification at the level of 100% of Recommended Intake (RI) per 100g to breads and instant o. dried noodles was estimated to result in a 15% decrease of proportion of those with iron less than EAR, while putting 1.4 % of the population greater than the Upper Limit (UL). Iron fortification appeared to be the most effective for the $15{\sim}19$ year old age group, showing 39% reduction of iron intake insufficiency. The results suggest that carefully designed fortification or enrichment to staple foods may contribute to increase dietary iron intakes of Koreans, especially for the young population with a high prevalence of iron inadequacy. As the estimation in this study was based solely upon dietary intake data, iron intake from supplements should be considered in further studies.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.125-126
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• 2015

According to the provisions of the United Nations, the proportion was 65 years of age or older population is 7% more than in the total population aged society. Due to the rapid decrease fertility and medical technologies and the improvement of living standards, the average life expectancy has emerged as an aging society. In the case of our country, and in 2011 the proportion of the population aged 65 and over 11.4%, the future is even faster aging rate is expected to launch in 2026, the super aged society. The days went by relying on caring for personal piety. Nursing crime is often due to the patriarchal family culture and afford. To care for patients with severe human or plant in the home, not to assume that society. Expanding the scope of long-term care insurance service person and the family burden reduced through measures to apply for health insurance, nursing care can prevent crime.

• Journal of the Korean Statistical Society
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• v.8 no.1
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• pp.3-14
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• 1979

When we estimate the population proportion of the individuals in the population for the attribute or the characteristic, we consider the sample survey. We can consider many methods of the sample survey, as mail questionnaire, visits, personal calls, etc. When we have the list of units in the population, we usually make use of the mail questionnaire. It is economical and free from the investigator's effect on the respondent, but it has some objections. The principal objection is that it involves a large nonresponse rate that might cause a singificant bias in the result. The bias arises from the different in the characteristics under investigation between those who respond and those who do not respond.

• Journal of Environmental Health Sciences
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• v.45 no.3
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• pp.273-284
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• 2019

Objective: This study was performed to estimate the number of those who used humidifier disinfectants (HDs) and experienced health effects from exposure to HDs in Korea between 1994 and 2011. Methods: A nationwide interview survey was conducted for the representative sample to identify the proportion of those who used HDs among the general population (n=3,001). Another online survey was conducted for those exposed to HDs to find the proportion of those who experienced health effects among those who were exposed to HDs (n=3,993). Statistics for population size by region and year (1994-2011) were used to estimate the cumulative number of those exposed to HDs and those who experienced health effects. In terms of the proportion of those exposed to HDs, those less than 30 years of age were excluded due to an issue related to information bias. Various approaches for estimation included the capture-recapture method for estimation of those who experienced health effects. Results: The cumulative proportion of those exposed to HDs was 6.7% among the general population, and the proportion of those who experienced health effects among those who were exposed to HDs was 13.9%. Based on these factors, it was estimated that 3.5 to 4.0 million people were exposed to HDs and 350 to 400 thousand experienced health effects at least requiring visiting a hospital. Conclusion: It is suggested that a nationwide representative sample may be essential for population size estimation of those exposed to environmental risk factors and of those who experienced health effects.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.635-641
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• 2021

This article analyzes the factors affecting income inequality in Vietnam, with data from 63 provinces and cities collected from the Vietnam Household Living Standards Survey of the General Statistics Office of Vietnam from 2010 to 2018. The article will firstly build a research model to identify factors affecting income inequality. Then, it uses the Generalized Method of Moments (GMM) method to evaluate the effect of factors on income inequality in Vietnam. The empirical estimate result shows that, in the period from 2010 to 2018, the factors such as the proportion of the working employees, income per capita, and inflation have positive effects on the Gini coefficient. That is, when these factors increase, there will be negative effects on improving income inequality in Vietnam. Conversely, when the factors such as the proportion of the literate adults, the proportion of the urban population, and population density increase they will have a positive impact on improving income inequality in Vietnam during this period. The estimated coefficients satisfied the sign expectation except the proportion of the literate adults. It means that, in Vietnam, the increase and more equilibrium in educational attainment balance the distribution of income and bring an improvement in income inequality.

• Communications for Statistical Applications and Methods
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• v.9 no.2
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• pp.389-399
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• 2002

In order to examine whether the difference between two point estimates of population proportions is statistically significant, data analysts use two techniques. The first is to explore the overlap between two associated confidence intervals. Second method is to test the significance which is introduced at most statistical textbooks under the common assumptions of consistency, asymptotic normality, and asymptotic independence of the estimates. Under the null hypothesis which is two population proportions are equal, the pooled estimator of population proportion is preferred as a point estimator since two independent random samples are considered to be collected from one population. Hence as an alternative method, we could obtain another confidence interval of the difference of the population proportions with using the pooled estimate. We conclude that, among three methods, the overlapped method is under-estimated, and the difference of the population proportions method is over-estimated on the basis of the proposed method.