• Title/Summary/Keyword: Lawn

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Series Dam Failure Simulation in Lawn Lake Dam Watershed (Lawn Lake Dam 유역의 연속댐 붕괴 모의)

  • Park, Se-Jin;Choi, Hyun-Gu;Kim, Pan-Gu;Han, Kun-Yeun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2012.05a
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    • pp.607-607
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    • 2012
  • 국내에서는 최근 지구온난화에 따른 전 지구적 이상홍수의 발생으로 댐 붕괴 우려가 증대되고 있고, 이에 따른 주민들의 불안감도 고조되고 있는 상황이다. 특히 최근 집중호우의 증가와 태풍의 영향으로 대규모 수공 구조물의 설계빈도를 초월하는 폭우를 동반하고 있다. 실례로 20세기 들어 전 세계적으로 약 200건 이상의 댐 붕괴 사고가 발생하여 댐 하류 지역에 막대한 인명 및 재산피해가 발생하였다. 국내의 경우 "연천댐", "장현, 동막저수지" 붕괴 등과 외국의 경우 이탈리아의 Vaiont 댐과 미국의 Teton 댐 등의 사례가 있다. 이처럼 댐은 설계홍수량 이하의 경우에는 비교적 안전하게 홍수를 예방할 수 있으나 이보다 큰 규모의 홍수가 발생할 경우 그 피해 또한 엄청나다. 따라서 댐 붕괴 등의 비상상황이 발생하였을 때 하류 지역의 생명과 재산 손실을 최소화하고 댐의 물리적, 지형적, 구조적 특성에 따른 비상상황을 예상하고 이에 효율적으로 대처하기 위해 비상대처계획(Emergency Action Plan, EAP)과 같은 대책을 수립하게 되었다. 이에 본 연구는 댐의 비상대처계획 수립시 중요한 사항 중 하나인 홍수류 해석을 실시하였다. 현재 국내에서 댐 붕괴 홍수류 해석은 주로 그 안전성과 정확성이 검증된 Fread(1984)의 1차원 모형인 DAMBRK 모형을 이용하여 댐 붕괴 홍수류 해석을 실시하고 있다. 이 DAMBRK 모형을 이용하여 실제 붕괴 사례인 1982년 미국 콜로라도에서 발생한 Lawn Lake 댐의 붕괴 홍수류 해석을 실시하였다. Lawn Lake 댐은 콜로라도 록키 마운틴 국립공원에 위치한 약 8m 높이의 필댐으로 댐 붕괴로 인하여 830,000 의 물이 유출되었으며, 3명이 사망하고 3,100만달러의 손해를 일으켰다. 다음과 같은 실제 붕괴 사례를 댐의 제원과 홍수량을 이용하여 DAMBRK 모의를 실시하였으며 모의한 결과와 실측치와의 비교를 해보았다. 본 연구에서 모의한 결과는 댐 최대 붕괴 유출량은 잘 나타내었지만, 지점별 최대 유량 및 홍수파 도달시간에 관련해서는 다소 차이를 보였다. 이는 조도계수의 변화에 따라 지점별 최대 유량과 홍수파 도달시간, 그리고 홍수위가 달라지는 것임을 확인하였고 실제로 Lawn Lake 댐이 붕괴되어 흘러들어가는 Roaring 강의 댐 붕괴 잔해나 하상 변화를 모르기 때문에 조도계수의 실측치는 모의값 보다 훨씬 클 것으로 예상된다. 본 연구를 통해 비상대처계획 수립시 홍수류 해석을 할 때 조도계수의 변화에 따라 모의 결과 및 범람범위가 달라질 수 있으니 조도계수의 채택에 있어 신중하고 정확한 판단이 필요할 것으로 판단된다.

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Development of Selective Heribicide for Control of Weeds in Turf (잔디밭 잡초방제(雜草防除)를 위한 선택성(選擇性) 제초제(除草劑)의 개발(開發)에 관한 연구(硏究))

  • Han, Seong-Soo
    • Korean Journal of Weed Science
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    • v.7 no.2
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    • pp.186-199
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    • 1987
  • This study was carried out to investigate the growth of Korean lawn grass (Zoysia japonica Steud.), penncross bentgrass (Agrostis palustris Huda) and seaside bentgrass (Agrostis spp.) under application of 21 pre- and post-emergence herbicides and the weeding effect of 14 annual and 4 perennial weeds with them for the purpose of the systematic chemical weed control in turf. The results obtained were as follows; 1. Napropamide, napropamide + triclopyr and benefin were safe for Korean lawn grass and two kinds of bentgrasses when they were treated at 4 and 25 days after transplanting of turfgrasses. Simazine, lenacil and bentazon inhibited the growth of bentgrasses, but not Korean lawn grass. 2. The preemergence application of simazine, benefin and napropamide + simazine showed excellent control for Digitaria sanguinalis, Cyperus amuricus, Chenopodium album, Portulaca oleracea and Centipeda minima. Lenacil was excellent for control of all the tested weeds except Chenopodium album, napropamide excellent for them except Cyperus amuricus and Portulaca oleraces, and bentazon good for them except Digitaria sanguinalis. When simazine was treated with either napropamide or triclopyr at preemergence of weeds, weeding effect increased without inhibition of lawn growth. 3. The postemergence application of mecoprop, bentazon, benefin + dicamba and benefin + mecoprop was safe to bentgrasses. All the tested postemergence herbicides except simazine + atrazine did not inhibit the growth of Korean lawn grass. 4. Other postemergence herbicides mecoprop and triclopyr were excellent for the control of Echinochloa crusgalli and those except benefin and mecoprop excellent for Kummerovia striata. Digitaria sanguinalis was controlled by treating with all the tested post emergence herbicides and Cyperus amuricus controlled only by bentazon. 5. The growth rates of bentgrasses treated with simazine, lenacil and napropamide + simazine were lower than that of hand-weeded check, and those of benefin, bentazon, napropamide, napropamide + triclopyr, stomp, bensulide and triclopyr were higher than that one when applied at spring season. Korean lawn grass growth appeared to be good under application of all the tested preemergence herbicides at spring. Lanacil and bentazone showed poor control of Echinochloa crusgalli, and bensulide showed poor control of Erigeron canadensis. Also, napropamide and bentazon were not good for Kummerovia striata control. However, at the respective rates of all the tested herbicides, these three weeds were greatly controlled by 85-100% of weeding effect. 6. At the application of autumn season, bentazon, napropamide, pendimethalin, benefin, napropamide + triclopyr, bensulide and triclopyr seemed to be safe against three kinds of turfgrasses. But simazine, napropamide + simazine inhibited the growth of bentgrasses except Korean lawn grass. In terms of weed control performance, triclopyr was poor for controlling Echinochloa crusgalli and bentazon and stomp for Poa annua, napropamide, benefin and bensulide for Stellaria medico. Stellaria uliginosa and Cerastium caespitosum were well controlled by all the tested preemergence herbicides. 7. Korean lawn grass was safe when paraquat and glyphosate were treated at the dormanant season of turfgrass. These herbicides showed excellent controll of Poa annua but poor control of perennials in order of Trifolium repens < Miscanthus sinensis < Calystegia japonica < Artemisia asiatica. 8. In field test, all of 19 herbicides seemed to be safe when treated at Korean lawn grass. All of 10 preemergence herbicides were excellent for controlling annual weeds, but poor for perennial ones. All of 9 postemergence herbicides showed a excellent control for broad-leaf weeds.

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Changes of the Nutritive Value and in vitro Digestibility as the Cutting Stages of Korean Lawn, Zoysia Japonica Steud. (한국잔디(Zoysia japonica Steud.)의 예취시기별 영양가와 in vitro 소화율의 변동)

  • 김형기;맹원재;장남기
    • Asian Journal of Turfgrass Science
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    • v.3 no.1
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    • pp.34-38
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    • 1989
  • This research was carried out to elucidate on standing crops , dry matter yields , the nutritive value and in vitro digestihility according to mowing frequency and period during the growing season in the 3cm moving plot in Korean Lawn , Zoysia japonica Sheud . The increasing tendency in the standing crops was showed yield from May to Septemher . In the dry matter yield , there was a tendency of rapid increase from May to August ( maximum level ). Afterwards there appeared a tendency of decrease slight ( Table 3). The nutritive value and in vitro digestihility ; The crude protein and crude fat in the 3cm moving plot showed a tendency of slight decrease as a moving period and frequency . On the other hand , Neutral detergeat fiber , Acid detergent fiber and cellulose showed a tendency of slight increase as mowing period and frequency . in vitro digestibility appeared a rapid decreasing rate as a mowing period and frequency was delayed (table 2.4).

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A Seedborne Fungus Bipolaris spicifera Detected from Imported Grass Seeds

  • Chun, Se-Chul;Loo, Han-Mo;Lee, Sang-Hun;Jung, Il-Min
    • The Plant Pathology Journal
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    • v.19 no.3
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    • pp.133-137
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    • 2003
  • Seedborne fungus Bipolaris spicifera, which has not been previously reported in Korea, was detected from import-ed grass seeds in the country. The most frequently detected fungi from the seeds were Fusarium species, Ulocladium atrum, B. spicifera, Alternaria, and Cuvularia lunata among 17 different seed samples of the family Gramineae. Detection frequencies of B. spicifera were 11,8,5% in Bermuda grass, tall fescue, and mixed lawn grass imported from USA, respectively, and 9% in mixed lawn grass imported from Italy. This suggests that important seedborne pathogen could be spread between countries through seed sources. The pathogen was seed-transmitted causing damping-off of Bermuda grass seedlings and showed strong pathogenicity to vice, corn, Bermuda grass, sorghum, and tall fescue. However, it did not infect wheat and blue grass.

Advanced Weed Control and Soil Environmental Survey in Lawn (잔디밭의 효과적인 잡초 방제와 토양 환경 조사)

  • 문영희;김용휘;김영석;양희석
    • Asian Journal of Turfgrass Science
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    • v.10 no.3
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    • pp.177-186
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    • 1996
  • The effects of salt are studied on control of weeds and growth of Korean turfgrass(Zoysia japon-ica Steud.). And the mobility of salt were determined in a lawn field. At post-emergence stage, the growth of the 13 weeds such as Trifolium repens, Erigeron canadensis, Artemisia prieceps, Equi-setum arvense, etc were controlled by treatment of salt and salt water, Pea-annua and Equisetum arvense were tolerant to salt compared with the other 11 weeds. At pre-emergence stage, the salt controlled the germination of the weeds in soil. 300~500 kg /10a salt and 20~30 % salt waterwere enough for the control of weeds, However, salt water injuried the lawngrass except the dormancy stage. The mobility of salt in soil was increased by rainfall. After 160mm of rainfall, the salinity in the soil treated with salt 500kg /l0a was below 0.3 ms/cm in surface soil and about 0.1 ms /cm in soil 30 cm depth. Key words: Soil environmental survey, Korean turfgrass, Salt, Salt water.

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Studies on the Classification Chracteristic of Lawn Weeds (잔디밭 잡초의 분류학적 특성에 관한 연구)

  • 이명선
    • Asian Journal of Turfgrass Science
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    • v.2 no.1
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    • pp.59-64
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    • 1988
  • This study was carried out to investigate the classification and the growing charicteristics of weed species in a newly formed lawngrass land. The results obtained are summarized as follows: 1)Weed population in a newly formed lawn field consisted of 30% of Gramineae, 15% of Compositae, and 12% of Leguminosae family. 2)Percentage of weed emergence between April and May was 39.4%. The same amount of weed emergence was observed at the period of September and October, where as the percentage was 21.2% at the period of March and April. 3)The population ratio of flowering date of weed species was in order of 48.5% July and August, 30.3% in May and July, 12.1% in March and April, and 9.1% in September and October. 4)Weed classification by life cycle showed 39.4% of biennials, 33.3% of annuals, and 27.3% of perennials. 5)Weed species were grouped according to the plant height. The ratios of each group were 33.3% of 20~40cm group, 27.3% of 40~60cm group, 24.2% of shorter than 20cm group, and 15.2% of taller than 60cm group.

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New record of five ciliate species from temporary ponds on a grass lawn

  • Jung, Jae-Ho;Yeo, Jeong Hyeon
    • Journal of Species Research
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    • v.9 no.1
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    • pp.68-76
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    • 2020
  • We identified 22 ciliate species, including five unrecorded ciliate species, from temporary ponds on a grass lawn. The five unrecorded species are as follows: class Nassophorea - Pseudomicrothorax agilis Mermod, 1914, Nassula exigua Kahl, 1931, class Colpodea - Cyrtolophosis mucicola Stokes, 1885, Maryna ovata (Gelei, 1950) Foissner, 1993, and class Spirotrichea - Meseres corlissi Petz & Foissner, 1992. Most of these 22 ciliate species disappeared from a raw culture within a few days (probably encystment), and a few cells were available from some species that resulted in incomplete identifications (e.g., genus-level). About the unrecorded five ciliate species, they are small in size (<60 ㎛ in vivo), and two of them live in a hyaline dwelling-tube, which is easily deserted by a cell with a stress. Their taxonomic classification is summarized as three classes, five orders, five families, and five genera. Here, we provide brief descriptions, micrographs of their morphology, and some remarks.