• Korea journal of population studies
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• v.4 no.1
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• pp.5-13
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• 1981

• Journal of Environmental Science International
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• v.8 no.5
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• pp.587-592
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• 1999

The purpose of this study was to identify the controlling factors to construct tidal flat ecosystems having similar characteristics as natural ones. We transplanted the soil in a constructed tidal flat to a natural one and vice versa. Parameters monitored after these transplantations were silt content, organic matter, bacterial population and oxidation-reduction potential. Moreover, the relationship among silt content, organic matter and bacterial population was investigated by laboratory column experiment. The silt content, organic matter, bacterial population and vertical profile of oxidation-reduction potential in the soil transplanted from the constructed tidal flat to the natural one changed to similar values to those in the natural one. On the contrary, all the parameters for the soil transplanted from the natural tidal flat to the constructed one changed to similar values as those in the constructed one. The silt contents in thses two transplanted solis were in proportion to the organic carbon contents and bacterial population. Similarly, the bacterial population in laboratory column experiment increased with the increase in silt and organic matter contents. It seemed to be important to select a place to enhance accumulative of silt and/or to maintain the silt content by hydrodynamic control of seawater in order to construct a tidal flat having similar characteristics as natural one.

• Korea journal of population studies
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• v.10 no.2
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• pp.82-98
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• 1987

The urban population in Asia more than doubled between 1960 and 1985, growing by 3.0 percent per annum on average. Yet during that period, the proportion of the total population living in urban areas increased only from 21 to 27 percent. This seeming paradox is explained by the relatively high rates of rural population growth in Asia, which averaged 1.8 percent over the same period. The Republic of Korea has experienced the most rapid rate of urbanization in Asia during the past century. The proportion urban jumped from 28 percent in 1960 to 65 percent in 1985. There is a clear association between economic growth and the pace of urbanization in Asia. Currently natural increase accounts for about 60 percent of urban growth, but the speed of urbanization is projected to increase after 1990, and migration, reclassification and annexation will comprise about half of urban growth, Seoul is currently the fourth largest urban agglomeration in Asia, and its population is projected to be over 13 million by the end of the century. It is argued that policies to deconcentrate urban population will not be generally successful in Asia and that governments should attempt to manage the growth of large metropolitan areas more efficiently.

• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.57-59
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• 2002

Because of the growing demand for protect and maintain one's health, population search for good water increase very rapid in recent. This study was performed to investigate the at 432 sites natural spring water quality in Seoul. Samples for analysis were collected form January to December in 2001. The quality of water was evaluated by analyzing fourty items of Korea drinking water criteria. The main results of this study were as follows 1. The rate of natural spring water was 26.6％ and the Total colony, E.Coli and Yersinia of the total incongruence cause was 67.9％ 2. The distribution of phisical-chemical item on the incongruence cause was Residues on evaporation 8.6％, Turbidity 4.3％, Nitrate nitrogen 2.5％, pH 2.5％ and F-1,2％ 3. The most population area of mean drinking population per one day was that man of Gangnam was 312.92 person. Next to Yangcheon Seocho Seodaemun and Dongjak was 229.6, 195.31, 190.50, 190,00 person. 4. The more person and the number of natural spring water, the more non passed drinking criteria natural spring water except for Gangnam and Gangbuk. 5. The corelationship of drinking population and results of the tests do not exist and the corelationship of results and Total colony, E.Coli, Color, Turbidity, KMNO4 consumption, Residues on evaporation, Fe, Mn, Zn and A1 are existed positive relationship.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.1-7
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• 2022

Background: In this study, we proposed that the population dynamics of non-native red-eared sliders (Trachemys scripta elegans) depends on the species' habitat extension and survivorship. We used a logistic equation with time-dependent habitat carrying capacity. In detail, the present carrying capacity depends on the red-eared slider population of the previous year. Anthropogenic activities such as the abandonment of previously captive red-eared sliders or the release due to religion customs would supply new habitats to the species. Therefore we assumed that anthropogenic spread increases the habitat carrying capacity. Based on the urbanization increase rate of 3% in Korea from 1980 to 2000, we assumed an annual spread of 3% to simulate the population dynamics of the red-eared slider. In addition, the effect on the population of an increase of natural habitats due to migration was simulated. Results: The close relationship between the distributions of non-native red-eared sliders and of urbanized areas demonstrates that urbanization plays an important role in providing new habitats for released individuals. Depending on the survivorship, the population of the red-eared slider in Korea increased 1.826 to 3.577 times between 1980 and 2000. To control population growth, it is necessary to reduce carrying capacity by reducing habitat expansion through prohibition of release into the wild ecosystem and careful managements of the wetland or artificial ponds. Changes in the habitat carrying capacity showed that the population fluctuated every other year. However, after several years, it converged to a consistent value which depended on the survivorship. Further, our results showed that if red-eared sliders expand their habitat by natural migration, their population can increase to a greater number than when they have a 99% survivorship in a fixed habitat. Conclusions: Further introductions of red-eared sliders into wetlands or artificial ponds should be prohibited and managed to prevent future spread of the species. Moreover, it is important to reduce the species' survivorship by restoring disturbed ecosystems and maintaining healthy ecosystems.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.267-273
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• 2000

In order to understand the impact for decomposition of blue-green algae Microcystis on water quality, the algae were cultivated with collection of natural population during approximately one month, when water-bloom of Microcystis dominated at August 31, 1999 in the lower part of the Okchon Stream. The enrichment of inorganic NㆍP nutrients didn't in algal assay and the effect of Microcystis on water duality was assessed from the variation of nutrients by algal senescence. Microcystis population seemed to play a temporary role of sink for nutrients in the water body. Initial algal density of Microcystis was 2.3×10/sup 6/ cells/㎖. When Microcystis population died out under light condition, algal NㆍP nutrients between 9∼12 days affected to increase of biomass after reuse by other algal growth as soon as release to the ambient water. However, cellular nutrients under dark condition were almost moved into the water during algal cultivation. NH₄, NO₃ and SRP concentration were highly increased with 160, 17 and 79 folds, respectively relative to the early. As a result, the senescence of Microcystis population seemed to be an important biological factor in which cause more eutrophy and increase of explosive algal development by a lot of nutrients transfer to water body. There are significantly observed an effort of reduce for production of inner organic matters such a phytoplankton as well as load pollutants from watershed in side of the water quality management of reservoir.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.85-92
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• 2000

The purpose of this study was to identify the controlling factors to construct tidal flat ecosystems having similar characteristics as natural ones. We transplanted the soil in a constructed tidal flat to a natural one and vice versa. Parameters monitored after these transplantations were silt content, organic matter, bacterial population and oxidation-reduction potential. Moreover, the relationship among silt content, organic matter and bacterial population was investigated by laboratory column experiment. The silt content, organic matter, bacterial population and vortical profile of oxidation-reduction potential in the soil transplanted from the constructed tidal flat to the natural one changed to similar values to those In the natural one. On the contrary, all the parameters for the soil transplanted from the natural tidal flat to the constructed one changed to similar values as those in the constructed one. The silt contents in these two transplanted soils were in proportion to the organic carbon contents and bacterial population. Similarly, the bacterial population in laboratory column experiment increased with the increase in silt and organic matter contents. It seemed to be important to select a place to enhance accumulative of silt and/or to maintain the silt content by hydrodynamic control of seawater in order to construct a tidal flat having similar characteristics as natural one.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.335-352
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• 2023

When solving multi-objective optimization problems, the blindness of the evolution direction of the population gradually emerges with the increase in the number of objectives, and there are also problems of convergence and diversity that are difficult to balance. The many- objective optimization problem makes some classic multi-objective optimization algorithms face challenges due to the huge objective space. The sine cosine algorithm is a new type of natural simulation optimization algorithm, which uses the sine and cosine mathematical model to solve the optimization problem. In this paper, a knee-driven many-objective sine-cosine algorithm (MaSCA-KD) is proposed. First, the Latin hypercube population initialization strategy is used to generate the initial population, in order to ensure that the population is evenly distributed in the decision space. Secondly, special points in the population, such as nadir point and knee points, are adopted to increase selection pressure and guide population evolution. In the process of environmental selection, the diversity of the population is promoted through diversity criteria. Through the above strategies, the balance of population convergence and diversity is achieved. Experimental research on the WFG series of benchmark problems shows that the MaSCA-KD algorithm has a certain degree of competitiveness compared with the existing algorithms. The algorithm has good performance and can be used as an alternative tool for many-objective optimization problems.

• Animal cells and systems
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• v.6 no.1
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• pp.19-22
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• 2002

Life table studies were conducted in the laboratory for the eulophid gregarious pupal parasitoid, Tetrastichus sp., on Hyphantria cunea Drury at a constant temperature of 28.2$\pm$2$^{\circ}C$, 50-60% RH to evaluate their impact on the host and their potential biological control. Development of immature stage took 20.1$\pm$2.7 d: adult females lived for 23.2$\pm$2.2 (range, 16-27)d and produced a mean of 53.6$\pm$26.6 adult progeny per female, with a sex ratio of 1: 9.5 (M:F). The intrinsic rate of natural increase (r$_{m}$) was 0.178/ female/day; the net reproductive rate (R$_{o}$), 46.74; the capacity for increase (r$_{c}$) 0.177; the finite rate of increase (λ) 1.19/female/day; thus each female contributed 46.74 individuals to the population in a mean generation time of 21.6 d. Biological factors in determining the life history trait variation of the parasitoid were discussed.d.d.d.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.3
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• pp.747-756
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• 2015

Brown alga Undaria peterseniana has been interested in the commercial scale aquaculture for warm water species development in southern coastal area of Korea. However, this species was classified an endangered species caused by a decrease in habitat and natural population. In this study, inhabit characteristics of U. peterseniana was investigated in their natural habitat of Ulleung Island, Korea. The U. peterseniana population was occurred dense patches at 20~30m depth. Total length of the alga reached 1.0~2.0m and the largest width ranged 10.0~35.0cm during the study. In 2013, habitats of this species increased two sites compared with the previous year and their distribution extended to low depth (10m) of coastal area. In long-term data, seawater temperature revealed a continuous increment by strong going north of East Korea Warm Current or Ulleung Warm Eddy turning around the coast of Ulleung Island. It suggested that habitat extension of U. peterseniana may be caused by suitable settlement condition and increase of warm water around the coastal area. Current studies of this species may be continuously required in the possibility of fisheries resources as aquaculture species and index species of increment of water temperature at the fixed monitoring site in East Sea. This is the first study to research ecological feature U. peterseniana population at the natural habitat of Ulleung Island.