• Journal of Korean Society of Forest Science
• /
• v.98 no.6
• /
• pp.659-668
• /
• 2009

Time series data on forest resources and population over the period from 1927 to 2007 were constructed and analyzed in order to identify trends and characteristics of forest transition in Korea. Korean forest transition could be classified into three phases in terms of the average annual growing stock of forest; forest degradation period (1927-1952), forest stagnation period (1953-1972) and forest growth period (1973-2007). Over the past 80 years forest area decreased 0.05% each year. The decreasing rate was very low, especially considering rapid economic growth and increased population of Korea with over 60% of forest cover. Growing stock per hectare significantly increased from $5.6m^3$ in 1952 to $97.8m^3$ in 2007, or 17.5 times during 1952 to 2007. Despise of increasing population and rapid economic growth, in particular, growing stock per capita has increased from $1.7m^3$ in 1952 to $12.9m^3$ in 2005 and un-stocked forest area decreased from 3,315 thousand ha to 165 thousand ha during the same period. In this regard, Korea represents a case of modern forest growth. Among 56 countries with more than 10 million of population and 10% or more of forest cover over the period 1990 to 2005, Korea is classified as a country which has high forest cover but low deforestation rate. Also, Korea is the only developing country which has 50% or more of forest cover and shows a below average deforestation rate.

• Food Science and Industry
• /
• v.54 no.2
• /
• pp.102-114
• /
• 2021

In Korea, a sugar company was first established at Pyongyang in 1920. But the real sugar industry began in 1953 when CJ Cheiljedang produced sugar at its Busan plant. Currently, three companies, CJ Cheiljedang, Samyang Corp., and TS Corp. are participating in the sugar industry. Sugar production increased from 647 tons in 1953 to 1,423 thousand tons in 2019. This means that the sugar industry has been grown by 2,200 times compared to 1953. Before 1953, all sugar consumed in Korea was imported, but now about 300 thousand tons, a 20 percent of sugar produced annually is exported. Population increase, economic growth, and food industry development contributed to the growth of sugar industry. However, recently the sugar industry has been stagnated due to the decrease of population and economic growth rate, and campaign of sugars and calories reduction. To overcome it, the continued development of various sugar application using emerging biotechnology is needed.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.1 no.2
• /
• pp.259-266
• /
• 1993

This experiment was carried out to the effect of population densities on the growth reproduction, cast production of the earthworm and chemical composition of worm casts. The population densities of 50, 100, 150, 200 and 250 individuals of the earthworm fed with cow manure was studied in rearing box($6,400cm^3$) and fertility stage during a period of 60 days. The results were summarized as follows 1. Survival rates(SR) of the earthworms had significantly positive correlated with increasing rate(IR). But, survival rates(SR) and increasing rate(IR) had significantly negative correlated with reproductive efficiency(RE). 2. The ranges of optimum population densities estimated were $42.7cm^3-128.0cm^3/worm$. 3. The cast production estimated were 36.5mg-80.9mg/day/worm grown in optimum population densities(50-150 worms/$6,400cm^3$). 4. The earthworm castings are an excellent soil conditioning material with a high chemical composition and their physical properties.

• Korean Journal of Plant Taxonomy
• /
• v.53 no.1
• /
• pp.1-8
• /
• 2023

Sustainable habitats play a significant role in determining the survival and habitat preservation of endangered species. To conserve the endangered species Iris dichotoma Pall. and its habitat in Taeanhaean National Park, we collected seeds from a natural population and germinated and propagated them in a greenhouse. In 2019, the propagated individuals of I. dichotoma were transplanted at two study sites in Taeanhaean National Park. After conservation translocation, annual monitoring was conducted from 2020 to 2022, and factors related to the survival and growth of I. dichotoma (clonal propagation rate [%], the flowering rate [%], the population density [individual/m²], the maximum leaf bundle length [height; cm], the maximum leaf bundle width [cm], and the pedicel length [cm]) were measured. According to the results of the monitoring of the flowering and fruiting periods for three years after transplantation, 82.4% of individuals in total were found to have survived. During 2020 to 2022, the mean population density (individual/m²) increased from 0.36 to 0.42 and the size of the leaf bundle length and the width both decreased compared to the corresponding figures in 2019 (p < 0.05). According to the findings here, the transplanted population of I. dichotoma is considered to have adapted successfully to its new site in Taeanhaean National Park.

• Environmental Engineering Research
• /
• v.23 no.4
• /
• pp.406-419
• /
• 2018

In planning public service systems such as waterworks, the design population is very important factor. Owing to the limitations of the indirect method, two new models, which take into consideration urban characteristics, were developed to accurately predict external migration rate (EMR), which is an essential component in estimating reliably the design population. The root mean square error (RMSE) between the model values and observed values were 10.12 and 15.58 for the metropolitan cities and counties respectively and were lower compared to RMSE values of 27.31 and 28.79 obtained by the indirect method. Thus, the developed models provide a more accurate estimate of EMR than the indirect method. In addition, the major influencing factors for external migration in counties were development type, ageing index, number of businesses. On the other hand, the major influencing migration factors for cities were project scale, distance to city center, manufacturing size, population growth rate and residential environment. Future medium and long-term studies would be done to identify emerging trends to appropriately inform policy making.

• Journal of the Economic Geographical Society of Korea
• /
• v.8 no.2
• /
• pp.267-284
• /
• 2005

This study analyzes the effects of localities' competitiveness which can contribute to employment growth in industries, on economic development in the local jurisdictions. For this analysis, such competitiveness is measured by competitive shares calculated from the application of a shift-share method to the employment growth in industries each locality witnessed over the 1990s. And we use annual population growth rate and average annual per capita income (substituted by per capita head tax derived from income tax) of the early 2000s as variables of local economic development. The analysis targets 167 local jurisdictions in Korea for the employment growth in industries, and is mainly placed in a spatial econometric setting. The results of analysis are as follows : The competitive share of manufacturing has the effect of increasing annual population growth rate whereas that of construction has a negative effect on the population growth rate. As well, the competitive shares of manufacturing and of construction negatively influence average annual per capita income while that of community, social and personal services positively affects the income.

• Korean Journal of Health Education and Promotion
• /
• v.31 no.1
• /
• pp.45-56
• /
• 2014

Objectives: This study aimed to examine how the relationship between socioeconomic factors at the macro level and suicide mortality rate of Korea was different from that of other OECD countries. Methods: We created OECD panel data of 29 OECD countries from 1985 to 2006 and analyzed the relationship between socioeconomic factors and suicide mortality rate for separate age and sex groups using a fixed-effect model. Economic factors included per capita GDP, per capita GDP growth rate, unemployment rate, and women's economic participation rate. Social factors included birth rate, alcohol consumption, and the percentage of population 65 and older. Results: Unemployment rate had a positive relationship with suicide in other countries but it had a negative relationship in some groups of Korea. Women's economic participation rate was both positively and negatively related with suicide in Korea but it did not relate to suicide in others. The negative relationship of birth rate and the positive relationship of alcohol consumption with suicide were evident in Korea, which were not found in other countries. The percentage of population 65 and older was negatively correlated in some female groups in Korea, while no significant relationship was found in other countries. Conclusions: Korea was substantially different from other OECD countries in the relationship between socioeconomic factors and suicide mortality rate.

• Journal of applied mathematics & informatics
• /
• v.30 no.1_2
• /
• pp.183-200
• /
• 2012

A two-strain epidemic model with an age structure mutation and varying population is studied. By means of the spectrum theory of bounded linear operator in functional analysis, the reproductive numbers according to the strains, which associates with the growth rate ${\lambda}^*$ of total population size are obtained. The asymptotic stability of the steady states are obtained under some sufficient conditions.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.21 no.1
• /
• pp.85-93
• /
• 2013

The amount of salted food waste and non-salted food waste from household consisted of 4 family members was surveyed. And the feeding rate and growth rate of Eisenia fetida population upon the different food wastes such as vegetables, grains, fruits and salted food waste were investigated. Total amount of food waste from a household was 3,200g/week. i.e. 0.114kg/day/capita and non-salted food waste was 53.9% of food waste. Salt contents of vegetables, grains, fruits were 0.60, 0.36 and 0.33%, respectively, if they were assumed to have 70% water content. Salt content of salted food waste was 0.78%. Upon the non-salted vegetables and fruits, feeding rate of earthworm was high but growth rate was low. Upon the non-salted grains, feeding rate of earthworm was low but growth rate was high. Upon the food with 70% water content, earthworm could not feed and grow when salt content of food was over 0.6%, and earthworm could feed normally but showed low growth rate when salt content of food was 0.3%. These results indicated that earthworm could stabilize the non-salted food wastes with ease but could hardly stabilize the salted food wastes.

• Korean Journal of Environmental Biology
• /
• v.39 no.3
• /
• pp.390-398
• /
• 2021

In this study, the toxicity of chlorothalonil was investigated using survival rate and population growth rate of a marine rotifer, Brachionus plicatilis, typically used in live food in marine aquaculture systems. The survival rate of B. plicatilis was determined after 24 h of exposure to chlorothalonil (0.010-0.156 mg L^-1). Population growth rate of B. plicatilis was calculated after 72 h of exposure to chlorothalonil (0.078-1.250 mg L^-1). The survival rate and population growth rate of B. plicatilis exposed to chlorothalonil in single-dose toxicity assessment showed concentration-dependent reductions. Survival rates of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.020mg L^-1; LOEC, 0.039 mg L^-1; and EC₅₀, 0.057 mg L^-1. Population growth rate of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.156 mg L^-1; LOEC, 0.313 mg L^-1; and EC₅₀, 0.506 mg L^-1. When the residual concentration of chlorothalonil in the marine coastal area was more than 0.039 mg L^-1, it had a toxic effect on B. plicatilis, a zooplankton. This paper provides toxicity values that can be used as baseline data for organizing environmental standards of chlorothalonil. It also provides insight into toxic effects of chlorothalonil on other non-target organisms.