• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.1-6
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• 2013

The ecosystem is the complex system consisting of various biotic and abiotic factors and the factors interact with each other in the hierarchical predator-prey relationship. Since the competitive relation spatiotemporally occurs, the initial state of population density and species distribution are likely to play an important role in the stability of the ecosystem. In the present study, we constructed a lattice model to simulate the three-trophic ecosystem (predatorprey- plant) and using the model, explored how the ecosystem stability is affected by the initial density. The size of lattice space was $L{\times}L$, (L=100) with periodic boundary condition. The initial density of the plant was arbitrarily set as the value of 0.2. The simulation result showed that predator and prey coexist when the density of predator is less than or equal to 0.4 and the density of prey is less than or equal to 0.5. On the other hand, when the predator density is more than or equal to 0.5 and the density of prey is more than or equal to 0.6, both of predator and prey were extinct. In addition, we found that the strong nonlinearity in the interaction between species was observed in the border area between the coexistence and extinction in the species density space.

• The Korean Journal of Ecology
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• v.24 no.6
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• pp.341-348
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• 2001

Population dynamics of the oldest relic stand of Pinus densiflora for. erecta which remains as a status of patch in Sokwang-Ri area, Uljin-Gun, was studied to provide the basic data for conservation of the oldest pine stand in Korea. The upper slope site and ridge site including total 12 plots mainly represented Pinus densiflora for. erecta and Quercus mongolica. These two tree species showed reverse J-shaped distribution. From this information, it was concluded that intensive interspecific competition between two species could be occurring. Age distribution of P. densiflora for. erecta on the sites above middle slope area was indicated bi-modal type or tri-modal type which was known as an age structure of climax forest. Therefore, it was estimated that Pinus densiflora for. erecta population could be continuously maintained in the each patch above middle slope area. In the valley sites, hardwood species such as Q. mongolica, Q. variabilis, Styrax obassia and Acer pseudosieboldianum occupied most part of the under crown-cover area and their seedlings and saplings were developing into the closed upper layer crown because the height of upper layer crown reached about 35 meters and such a high crown height was more suitable for light utilization by plants of under layer. The growth patterns were mainly fluctuated for the entire life time of the oldest tree caused by frequent disturbance. And the initial growth curves of the mature trees and suppressed juvenile trees showed different tendencies along the sites.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1525-1535
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• 2020

Synthetic dyes are widely used in various industries and their wastage causes severe environmental problems while being hazardous to human health, leading to the need for eco-friendly degradation techniques. The split-gill fungus Schizophyllum commune, which is found worldwide, has the potential to degrade all components of the lignocellulosic biomass and is a candidate for the treatment of synthetic dyes. A systematic molecular analysis of 75 Korean and 6 foreign S. commune strains has revealed the high genetic diversity of this population and its important contribution to the total diversity of S. commune. We examined the dye decolorization ability of this population and revealed 5 excellent strains that strongly decolorized 3 dyes: Crystal Violet, Congo Red and Methylene Blue. Finally, comparison of dye decolorization ability and the phylogenetic identification of these strains generalized their genetic and physiological diversity. This study provides an initial resource for physiological and genetic research projects as well as the bioremediation of textile dyes.

• The Korean Journal of Ecology
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• v.11 no.2
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• pp.55-64
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• 1988

The seasonal pattern of pool size and withdrawal from senescing or stroage organ, and the annual magintude of internal-and plant-soil cycles for nitrogen and phosphorus in a Glyceria leptolepis Ohwi population in a marsh of the Mt. Geumoh were investigared. The population pool changed from initial size of 6.8 to the maximum of 16.1gN$m^{-2}$ for N and from 1.7 to 3.9g Pm$m^{-2}$ for P, maintaining far higher relative pool size during the first half of the growth period as compared with that for biomass. A sharp increase in N and P pool was noticed in early spring before the biomass growth was recognized, The major process supplying the demand for N and P changed as the growth progressed showing the order; absorption-withdrwal-absorption-with-drawal. The annual magnitude of plant-soil cycle for N and P was 18.0-19.1 and 2.9-3.3gm$m^{-2}$, accounting for 3 and 5% of each nutrient pool in 0-20 cm humus layer, respectively. The higher exent of internal cycle and the lower rate of annual turnover for P(1.08) as compared with those for N may suggest that this population conserves and reuses P more efficiently than N.

• 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 Korean Society of Grassland and Forage Science
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• v.15 no.4
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• pp.253-258
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• 1995

'Ihis experiment was carried out to select a carrier as rhizobium inoculant for alfalfa. The Rhizobium inoculants were produced in main materials(organic and inorganic materials) and submaterial(Ca$CO_3$, and sucrose), and than the changes of Rhizobium population of inoculants were scrutinized from directly after the production to 12 months at $4^{\circ}$C and $25^{\circ}$C. Directly after the production of inoculants, their Rhizobium numbers were 4-9 $\times$ $10^9$/ginoculant in organic materials and 1-8 $\times$ $10^8$/g inoculant in inorganic materials. When they were stored at $25^{\circ}$C, most of inoculants was being started in reduction of rhizobium numbers after 2 months and was reduced by tenfold of initial rhizobium number after 4-6 months, but inoculant of bentonite+ vermiculite+sucrose 1% was not reduced by tenfold after 12 months. When they were stored at $4^{\circ}$C, most of inoculants was being started in reduction of rhizobium numbers after 4 months but was not reduced by tenfold of initial rhizobium number after 12 months, and the effect of sucrose addition to bentonite+ vermiculik did nearly not appear. Preservation of Rhizobium inoculants was more effective at 4C than 25 C . 'Ihe Rhizobium inoalant produced in bentonite+vermiculite(l:3 w/w)+ sucrose 1% was not only high Rhizobium population(8.3 $\times$ $10^8$/g inoculant) but also survival effect of rhizobium in being stored at $25^{\circ}$C.

• Korean journal of applied entomology
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• v.27 no.1
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• pp.35-40
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• 1988

The control efficiency of the nematicides, aldicarb and carbofuran, in the population dynamics of the soybean cyst nematode(Heterodera glycines)was evaluated. Nematode viability, penetration and reproduction were examined in greenhouse experiments. Nematode viability(movement) was greatly reduced by aldicard, but mot by carbofuran. Penetration was inhibited by both chemicals. Percentages of Pentration relative to the untreated check 3 days after treatment were 0.4% and 1.7% for aldicarb and carbofuran, respectively. Systemic effect ot the nematicides were observed with both nematicides but effect was greater with aldicarb than with carbofuran. The total effect of the nematicides, applied ay the time of planting soybean in infested soil, appeared to be less than the sum of the contact and systemic effects on the initial population dynamics of H. glycines.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.115-120
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• 1997

The purpose of thesis was to investigate the removal efficiency of surfactants and commercial detergents by Oenanthe javanica that is one of aquatic plants in Korea. The experiment is concerned with measuring the concentrations of surfactants and commercial detergents in different media: 1) in pure water, 2) in water containing Oenanthe javanica, 3) in water containing Oenanthe javanica and commercial nutrients. The surfactants used in this research include linear alkylbenzene sulfonates (LAS), $\alpha$-sulfo fatty acid methyl esters(MES), and alkylbenzene sulfonates(ABS). Two commercial detergents designated as A and B were in the forms of power and liquid. The results showed that LAS and MES were more effectively removed by Oenanthe javanica probably because these have a chain of linear carbon than on ABS with a branched carbon structure. In the case of commercial detergents, when the except was performed on the basis of surfactants proportion, the removal trends were similar to LAS and MES. The 5-day cultivating test with initial concentration of 0.5-1.0 ppm surfactants showed that less than 10% was removed if no nutrients an Oenanthe javanica were added. When Oenanthe javanica was added into the sample solution containing surfactants, the removal efficiency was increased 100% for the solution containing 0.5-1.0 ppm 60-70% for 5-10 ppm. In addition, chlorisis on Oenanthe javanica was observed due to surfactants and commercial detergents for all three cases. To test the dependence of population density on nutrients, the initial population density was made 300 g/0.4 m$^2$. Throughout the 5-day experiment, the on Oenanthe javanica grew 20-25% with 0.5-1.0 ppm without the synthetic nutrients but by 5% with a high concentrations of 5-10 ppm. The population density was appeared to be independent of synthetic nutrients. The leaves were to be grown with synthetic nutrients, while roots were grown without synthetic nutrients. Based on this research, the fundamental data concerning cultivation and an adequate adjustment of the water condition can provide for the utilization of Oenanthe javanica in real water treatment system.

• Physical Therapy Rehabilitation Science
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• v.3 no.2
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• pp.86-92
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• 2014

Objective: Whole body vibration (WBV) and plyometrics are common training techniques which increase strength, blood flow, and lower body force and power. The effects these techniques have on sedentary population is unknown. It is our aim to assess the effectiveness of WBV and plyometrics on sedentary population. Design: Experimental study. Methods: Twenty-seven sedentary subjects were assigned to either the control group, jumping only group, or jumping with vibration group. Jump height (myotest or vertec), velocity, force, blood lactates, and rating of perceived exertion (RPE). Subjects were measured on the initial, seventh, and eighteenth visits. Control group attended measurements only. Jumping only and jumping with vibration groups performed jumping from a vibrating platform to a surface 7 1/2 inches higher for 3 bouts of 20 seconds. Each subject in jumping only and jumping with vibration groups attended three times per week for six weeks. Vibration was set at 40 Hz and 2-4 mm of displacement. Results: There was no significant change among groups in force, velocity, vertec height, and myotest height. However there was a significant increase in vertec height from initial to final measure (p<0.05) for jumping with vibration group. RPE was significantly higher between control group and jumping with vibration group after intervention (p<0.05). Conclusions: WBV with vibration increased jump height. Jumping with vibration group experienced increased exertion than for controls. WBV with plyometrics had no effect on force, velocity, blood lactates, or calculated jump height. Further studies controlling for initial measure of blood lactates and using an external focus may be necessary to elicit velocity, force and jump height changes.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.2
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• pp.181-186
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• 2017

Objective: Leucaena leucocephala (Leucaena) is a perennial tropical legume that can be directly grazed or harvested and offered to ruminants as hay, silage, or fresh. However, Leucaena contain phenolic compounds, which are considered anti-nutritional factors as these may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects of Leucaena silage (LS) feeding levels on rumen microbial populations, N-balance and microbial protein synthesis in dairy steers. Methods: Four, rumen fistulated dairy steers with initial weight of $167{\pm}12kg$ were randomly assigned to receive dietary treatments according to a $4{\times}4$ Latin square design. Treatments were as followings: T1 = untreated rice straw (RS; Control), T2 = 70% RS+30% LS, T3 = 40% RS+60% LS, and T4 = 100% LS. Dairy steers were fed rice straw and LS ad libitum and supplemented with concentrate at 0.2% of body weight/d. Results: Results revealed that the rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers that received 60% of LS (p<0.05), whereas the amylolytic bacteria population was not affected by treatments (p>0.05). Protozoal population was linearly decreased with increasing level of LS (p<0.05). Moreover, N-balance and microbial protein synthesis were enhanced by LS feeding (p<0.05) and were the highest in 60% LS group. Conclusion: Based on this study, it could be concluded that replacement of RS with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.