• Title/Summary/Keyword: Covering material

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Effects of different covering material on stable winter survival management with edible leaf in ramie (Boehmeria nivea L.).

  • Kim, Myeong Seok;An, Ho Sub;Kim, Gil Ja;Kim, Yong Soon;Choi, Jin Gyung;Kim, Dong Kwan;Park, Heung Gyu;Kim, Hyun Woo;Kim, Seong Il
    • Proceedings of the Korean Society of Crop Science Conference
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    • pp.226-226
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    • 2017
  • This study was to evaluate methods to high quality food ramie rice cake, thereby increasing farm income. This study investigated the effects of different covering material on stable winter survival management with edible leaf in Ramie(Boehmeria nivea L.). The method of winter survival with covering material were conducted under three condition compose to Non covering, Rice straw cutting covered with 500kg.10a-1, Rice husks covered with 1,000kg.10a-1(covered 4~5 cm thickness in the soil surface). Method of application were standard application(N-P-K-Compost applied at 27-9-27-600kg.10a-1. Compost and fused phosphate applied at 100% of basal fertilizer in March 25. 20% of top dressing were four times application in March 25 - October 5. Planting year were March 15, 2011. Plants were spaced 60 cm apart in rows 25 cm apart with open cultivation. According to non covering < Rice husks covered with 1,000kg.10a-1 < Rice straw cutting covered with 500kg.10a-1 cultivation this order, aerial part as a result were plenty amount of growth. Sprout time and winter survival rates was uncovering control plot compared to 2 - 5 days quickly, 45-57% highly by rice husks and rice straw covering. Green leaf yields is untreated control plot (12,44 kg.10a-1) compared to rice husks covering 7% higher, and rice straw covering increased to 18% of the most.

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An Experimental Study on the Corrosion Characteristics of Reinforcement Concrete According to Types of Surface Covering Material (표면피복재 종류에 따른 철근콘크리트의 철근 부식특성에 관한 실험적 연구)

  • 김갑수;장종호;김재환;김용로;오시덕;김무한
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.39-43
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    • 2003
  • Chloride ions are considered to be the major cause of steel corrosion in concrete structures exposed to seashore environments and also permeation of chloride is controlled by chloride diffusion. Therefore, the study on chloride diffusion of concrete have been done so far by many researchers. It is reported that coating material as surface covering material is effect about deterioration of salt damage and carbonation, therefore these materials are important in durability of concrete structure. In this study, corrosion characteristics of reinforcement concrete according to types of surface covering material were evaluated by water-cement ratio, chloride penetration by age on the corrosion area rate and mass decrement of reinforcement. And it is considered that the result of this study on application of the corrosion characteristics of reinforcements under salt damage environmental will be suggested as fundamental data of control performance of salt damage. It is performed that comparison and examination of control performance of salt damage by the corrosion characteristics under salt damage environmental.

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Study on the Mechanical Properties of Lightweight Mortar for Fire Protection Covering Material in High Strength Concrete (고강도콘크리트용 내화피복재로 활용하기 위한 경량모르타르의 역학적 성상)

  • Lim, Seo-Hyung;Yoo, Suk-Hyung;Moon, Jong-Woog
    • Fire Science and Engineering
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    • v.25 no.5
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    • pp.8-13
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    • 2011
  • High strength concrete is the occurrence of explosive spalling associated with high temperature such as a fire. The spalling causes the sever reduction of the cross sectional area with the exposure of the reinforcing steel, which originates a problem in the structural behaviour. The purpose of this study is to investigate the mechanical properties of lightweight mortar using perlite and polypropylene fiber for fire protection covering material. For this purpose, selected test variables were the ratio of water to cement, the ratio of cement to perlite, contents of polypropylene fiber. As a result of this study, it has been found that addition of perlite and polypropylene fiber to mortar modifies its pore structure and reduces its density. And it has been found that a new lightweight mortar can be used in the fire protection covering material.

Properties of Temperature History of Lightweight Mortar for Fire Protection Covering Material in High Strength Concrete (고강도 콘크리트 내화피복용 경량 모르터의 온도이력 성상)

  • Lim, Seo-Hyung
    • Fire Science and Engineering
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    • v.26 no.6
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    • pp.45-50
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    • 2012
  • The spalling causes the sever reduction of the cross sectional area with the exposure of the reinforcing steel, which originates a problem in the structural behaviour. By coating surface of high strength concrete with fireproof mortar, the high strength concrete is protected from the spalling in fire and the method to constrain the temperature increase of steel bar within the concrete. The purpose of this study is to investigate the temperature history properties of lightweight mortar using perlite and polypropylene fiber for fire protection covering material. For this purpose, selected test variables were the contents and length of polypropylene fiber. As a result of this study, it has been found that addition of polypropylene fiber to mortar modifies its pore structure and this causes the internal temperature to rise. And it has been found that a new lightweight mortar can be used in the fire protection covering material.

Variation of Photosynthetic Photon Flux in Commercial Plastic Greenhouses (상업용 플라스틱 온실의 광합성유효광량자속 변화)

  • Lee, Hyun-Woo;Kim, Young-Shik
    • Current Research on Agriculture and Life Sciences
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    • v.30 no.1
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    • pp.27-33
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    • 2012
  • This study was conducted to provide data necessary for clearing up the way to be able to improve covering and management method of covering material in commercial plastic greenhouse. The photosynthetic photon flux(PPF) in representative 4 different commercial tomato greenhouses was measured and analyzed. The variation trend of daily integral PPF was in agreement with that of the duration of sunshine. Each of daily integral PPF for 4 different experimental greenhouses was quite dissimilar, and was less than the amount of PPF necessary to grow tomato. October to November of beginning of winter was a good season to replace covering material in order to secure more PPF during insufficient winter season in greenhouse. The main inside factors to interrupt PPF incidence were thermal screen, inside covering material, condensation receiver in greenhouse. The single wide span greenhouse covered with PO film was superior to the other experimental greenhouses in the aspect of PPF transmittance.

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Effects of Greenhouse Covering Material on Environment Factors and Fruit Yield in Protected Cultivation of Sweet Pepper (파프리카 재배 온실의 피복재 종류에 따른 환경요인과 수량성)

  • Kim, Ho-Cheol;Jung, Sek-Gi;Lee, Jeong-Hyun;Bae, Hyang-Jong
    • Journal of Bio-Environment Control
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    • v.18 no.3
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    • pp.253-257
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    • 2009
  • To analysis effect of environment factors on productivity of sweet pepper according to greenhouse covering material (glass, plastic film), this was investigated. In glasshouse, outside light was positively correlated with yield as that $100MJ{\cdot}m^{-2}$ of outside light increased $300{\sim}500g{\cdot}m^{-2}$, also cumulative temperature was same tendency. On possibility of model development for yield estimate cumulative temperature was high than outside light. According to covering material, leaf photosynthesis, productivity per out-side light and term in glasshouse was more high 13%, 46%, and 47% compared with plastic film house, respectively. Result of analysis of effect of light, temperature, and $CO_2$ on yield, relative yield coefficient, yield increment coefficient, and yield reduction coefficient in glasshouse were more high 25%, 73%, and 34% compared with plastic film house, respectively. Hence, sweet pepper's growing in glasshouse compare with plastic film house had more productivity, but that had more sensitivity to charge of environment factors.

Buckling Characteristics of Rigidly-jointed Single-Layer Latticed Domes with Square Network -Comparison between Experiment and Analysis- (사각형네트워크 단층래티스돔의 좌굴특성 -실험과 이론과의 비교-)

  • Jung, Hwan Mok
    • Journal of Korean Society of Steel Construction
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    • v.10 no.3
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    • pp.463-472
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    • 1998
  • The purpose of this paper is to analyze the buckling characteristics of rigidly-jointed single-layer latticed domes with square network by using the experimental and the theoretical techniques in order to develop a reasonable method of theoretical analysis for these domes. Two methods of theoretical analysis are applied; one is based on the Yamada's method of shell analogy and the other is based on the frame analysis method using the finite element method. The effects of the nonuniformity of rigidity-distribution in the circumferential direction and the rigidity of the covering material on both the prebuckling and the buckling characteristics are examined. The results indicate that these effects should be considered reasonably in the theoretical analyses.

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Effect of Canopy Covering on Thermal Insulation and Freezing Tolerence of 'Shiranui' Hybrid Mandarin Cultivated in Field During Winter Season (수관 피복이 노지재배 '부지화' 감귤나무의 보온과 내한성에 미치는 영향)

  • Joa, Jae-Ho;Kang, Seok-Beom;Moon, Young-Eel;Lee, Hae-Jin
    • Journal of Bio-Environment Control
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    • v.30 no.4
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    • pp.441-447
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    • 2021
  • It were investigated changes in internal and external temperature, relative humidity using tyvek, weedstop, and 35% shading net as covering material to reduce the freezing damage of 'Shiranui' hybrid mandarin grown in open field. It were also evaluated canopy covering effect and LT50 of leaves by covering material when it was cold at -2℃. In tyvek, temperature difference between inside and outside was low at the height of 1.5m and was high at 0.4m. The relative humidity differed greatly between day and night, and was high at 6-8 a.m. At -2℃, Sum of temperature at the height of 1.5m of canopy for 24-hour after covering were at 3.4℃ higher in tyvek than in control. The LT50 of leaves was at 1.51℃ in tyvek, 1.33℃ in withstop, and 1.61℃ in 35% shading net lower than in control. Considering thermal insulation and relative humidity in canopy, tyvek is expected to reduce low temperature damage when covering after making a fine hole for ventilation.