• Title/Summary/Keyword: disappearing

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Causal Loop-Based Structural Analyses of Marginal Ageing and Critical Mass Simulations for Demographic Extinction Scenarios in Eup and Myeon Regions (읍·면지역 한계고령화의 인과순환적 구조분석과 인구소멸 임계점에 대한 시뮬레이션)

  • Choi, Nam-Hee
    • Korean System Dynamics Review
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    • v.17 no.1
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    • pp.107-134
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    • 2016

  • Accelerated ageing with low fertility is one of the most critical problems in Korea. Because of ageing via low fertility, Korea will face a serious demographic cliff. This research primarily focus on the analyzing the dynamics of the marginal ageing state and decreasing population especially in Eup and Myeon region. This study based on the system dynamics approaches for finding causal loop structure of marginal ageing and critical mass of population disappearing. The results of this study are summarized as follows. First, demographic marginalization trends have already begun in the Eups and Myons of Gun. Second, marginal aging speed in Eup/Myeon areas is causing an population disappearing in the near future. Third, critical mass of population disappearing will begin when the rate of marginal aging is exceed 82% after 2023.

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The Role of Phosphorus on Plant Succession of Grassland in Andosol Region II. Accumulation and decomposition of litter in natural grassland community (강산성 화산회토양에 있어서 초원의 천이에 미치는 인산의 역할 II. 야초군락에 있어서 Litter의 집적과 분해)

  • Chung, Chan;Sugawara, Kazuo
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.13 no.1
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    • pp.23-30
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    • 1993

  • This study was investigated about decomposition process of litter that is reduction pathway of phosphorus from plant body to soil That is, in each community of Miscanthus sinensis, SaSa palmalta. Artemisia princeps and Polygonum thunbergii, disappearing speed was calculated from total fallen leaves yield supplied as litter and litter existant yield. Besides, setting up litter bag that put litter in nylon mesh bag. calculated disappearing speed from decreasing speed of the weight of contents and then was compared and examined. The results obtained are summarized as follows : 1. Maximum litter yield was sequently Miscanthus sinensis＞SaSa palmalta＞Artemisia princeps＞Polygonum thunbergii, but, supplied litter yield was sequently Artemisia princeps＞Miscanthus sinenis＞Polygonum thunbergii＞SaSa palmalta. 2. Reduction speed of phosphorus from plant body to soil was Polygonum thunbergii＞Artemisia princeps＞Miscanthus sinensis＞SaSa palmalta. 3. Caculated disappearing speed using litter bag method was shown latter tendency than that of natural condition. 4. It was significantly negative relationship between N contents of litter and disappearing speed of litter.

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Toxicity of Fungicides in vitro to Cylindrocarpon destructans

  • A.Monique Ziezold;Robert Hall;Richard D.Reeleder;John T.A.Proctor
    • Journal of Ginseng Research
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    • v.22 no.4
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    • pp.223-228
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    • 1998

  • As part of a study on the ability of fungicides to control disappearing root rot of ginseng (Panax quinquvdius) caused by Cylindruarpn destmtans, 15 fungicides were screened for toxicity to the fungus in vitro. Highly toxic fungicides were Benlate (benomyl), Thiram (thiram), and Orbit (propiconazole). EC5O values (mg a.i./L) were less than 1 and EC95 values were less than 10. Crown (carbathiin and thiabendazole), ASC-66835 (fluazinam), and UBI-2584 (tebuconazole) were moderately toxic, with EC5O values in the range 1-10 and EC95 values in the range 32-45. Weakly toxic fungicides (EC5O in the range 20-80, EC95 in the range 35-140) included UBI-2643 (thiabendazole), UBI-2565 (cyproconazole), and Vitaflo-280 (carbathiin and thiram). Anvil (hexaconazole), Vitaflo-250 (carbathiin), UBI-2383 (triadimenol), Daconil (chlorothalonil), CGA-173506 (fludioxonil), and CGA-169374 (difeno- conazole) were considered nontoxic to C. destmtan (EC5O 1.29->600, EC95>500). Relations between proportional inhibition of growth and concentration of fungicide were linear on arithmetic plots (Benlate, UBI-2643, UBI-2565, Vitaflo-280) or logarithmic plots (all other fungicides). Based on toxicity in vitro and formulation, it is recommended that Benlate, Orbit, and ASC-66835 be tested as soil drenches, and Benlate, Thiram, UBI-2584, and Crown be tested as seed treatments for controlling disappearing root rot.

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Effect of Drenching Soil with Benomyl, Propiconazole and Fluazinam on Incidence of Disappearing Root Rot of Ginseng

  • A.Monique Ziezold;Robert Hall;Richard D.Reeleder;John T.A.Proctor
    • Journal of Ginseng Research
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    • v.22 no.4
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    • pp.237-243
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    • 1998

  • Three fungicides, Orbit (propiconazole), Benlate (benomyl) and ASC-66835 (fluazinam), were tested as soil drenches to control disappearing root rot (DRR) of ginseng (Panax quinquefolius) in gardens artificially infested with Cylindrocarpon dsstrutans. The incidence of DRR was low (0∼3.5%) in uninfected plots and significantly higher in infested plots (2.6∼19.9%). Significant reductions in the incidence of DRR were observed in 1-year-old and 2-year-old gardens that were treated and assessed for disease in the same year Significant control was not obtained in 3-year-old gardens treated and as secede in the same year, or in 1-year-old or 2-year-old gardens assessed in the year following information. Disease incidence was significantly reduced by 49-77% by low and high rates of benomyl (45 and 1,250 mg a.1./L) and propiconazole (10 and 40 mg a.i./L) and by fluazinam at 150 mg a.i./L. These fungicides seem to be worthy of further investigation as soil drenches to control DRR of ginseng.

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