• 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.

• Journal of Bio-Environment Control
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• v.11 no.2
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• pp.88-92
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• 2002

The study was conducted to estimate stimulation of plant growth of blue and red leaf lettuce (Lactuca sativa L.) as affected by covering methods with vinyl materials containing concentrated PO film. Plants were grown in direct, direct and tunnel, and tunnel covering with 'Pasraido materials' from October 13 to 31. With the covering mean air temperature, soil temperature, leaf temperature and relative humidity remarkedly increased. Higher temperature was observed in the order of direct and tunnel, direct, tunnel covering and the control. Photosynthetic photon flux (PPF, $\mu$mol m$^{-2}$ . s$^{-1}$ ) was observed in reverse order of temperature. Concentration of $CO_2$ was higher during night than during day under the light. Accumulation of highest $CO_2$ at night was obtained from direct coverings followed by direct and tunnel, tunnel covering and the control. Plant height, leaf number and leaf area of blue and red lettuces were stimulated by direct covering. However, there was no significant difference.

• Korean Journal of Medicinal Crop Science
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• v.13 no.6
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• pp.287-292
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• 2005

To investigate the effects of heat conservation materials on freeze damage and weed occurrence during overwintering in Saururus chinensis, Temperature difference was $6.9^{\circ}C$ in chaff, and was lower than those ranged from 9.7 to $14.4^{\circ}C$ in other materials. Heat conservation index, calculated from average temperatures below $-10^{\circ}C$ of earth's surface during the winter, was higher $1.7^{\circ}C\;and\;1.5^{\circ}C$ in chaff and lagging, respectively than in straw. Preservation of water is greater $9.6{\sim}26.1%$ in covering than in open field, and it increased in the order of lagging > chaff > straw among heat conservation materials. The survival rate of rhizome was increased in the order of 99% in lagging > 75% in chaff > 58% in straw, 32% in open field after overwintering, budbreak began fast, and the numbers of total budbreak per unit area were greater 22 times in lagging than 35.0 units in open field. Weeds occurrence was decreased in covering, i.e., $12.0{\sim}33.2\;units/m^2,\;7.3{\sim}10.7\;kg/10a$ of dry weight, and $5.6{\sim}6.4\;hours/10a$ of labor input compared with $157.2\;units/m^2,\;28.9\;kg/10a$ of dry weight, and 65.7 hours/10a of labor input in open field. Growth of top part was better in covering than in open field, and the number of tillers per unit area showed $347{\sim}396$ compared with 293 in open field. Marketable yields of dried stem and leaves and rhizome were higher $69{\sim}87%\;and\;58{\sim}88%$, respectively in covering than in open field, and among heat conservation materials, those were highest in lagging.

• 어항어장
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• s.78
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• pp.39-43
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• 2007

1976년에서 2006년까지 30여년 간의 피해사례자료에 의하면 총 38개항에 시설 피해가 발생하였는데, 피해시설물 대부분이 방파제이다. 피해형태를 보면 사면 피복재 및 사설 유실이 대부분으로 나타났으며, 패해가 2회 이상 발생한 항이 전체발생횟수의 약 70%로 반복 피해사례가 많았다.

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.8-13
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• 2011

This research was carried out to investigate relationship between underground part environment control and growth or yield of sweet pepper in greenhouse as affected by covering materials. Daily amount of applied nutrient solution for research period in the greenhouse of plasticfilm house was more 1.6 times than that in glass house. But daily absorptance rate of nutrient solution and specific electrical conductance of rockwool between two greenhouses were not different in the range of 71.3-73.3% and $4.17{\sim}4.23dS{\cdot}m^{-1}$ respectively. Leaf area of sweet pepper, in leaf growth characteristics in two greenhouses, were $123.0cm^2$/leaf (in glass house) and $119.5cm^2$/leaf (in plasticfilm house), but the another (fresh and dry weight, dry matter) were not different. But weekly yield per square meter in glass house was more 1.3 times than that in plasticfilm house as $850g{\cdot}m^{-2}$ and $650g{\cdot}m^{-2}$, respectively. Effect of slab EC and absorptance rate of nutrient solution on leaf growth characteristics and yield between two greenhouses were not different. The results show when sweet pepper is cultured in greenhouse as affected by covering materials and above ground part environment, the plant growth and yield are little affected by underground part environment.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.312-316
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• 2012

This study evaluated the effect of polyolefine greenhouse covering film on growth of lettuce and cucumber. The growth of lettuce and cucumber plants under conventional film (polyethylene plus ethylenevinyl acetate, PE + EVA) and polyolefine (PO) film were evaluated in a greenhouse. The physical qualities of PO film, such as tensile strength and tear strength, were stronger than conventional PE + EVA film. PO film showed 4% higher transmission performance in photosynthetic active radiation (PAR) than PE + EVA film. The average day and night temperature in greenhouse under PO film were $1.5^{\circ}C$ and $0.8^{\circ}C$ higher but there was no significant difference in relative humidity compared with conventional film. Chlorophyll content of lettuce and cucumber plants grown under PO film were higher than conventional film. Growth characteristics; plant height, leaf area, fresh weight and dry weight of cucumber was shown better for PO film. The yields of cucumber and lettuce was increased 14.0% and 13.6% respectively, when the crops were grown under PO covering film greenhouse.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.11a
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• pp.96-101
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• 2001

동계의 노지 및 무가온 시설재배시에 상추와 시금치 등의 엽채류 재배는 생육이 거의 정지되는 온도에서 재배되고 있다. 이와 같은 저온기의 불량환경조건을 개선하기 위하어 저온성 엽채류에 직접 피복할 수 있는 통기성 피복자재가 개발되어 생육촉진이나 품질향상을 위한 연구가 지속되어 왔으나 피복방법의 개선에 관한 연구는 아직도 미흡한 실정이다. (중략)

• Journal of Korea Technology Innovation Society
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• v.20 no.4
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• pp.939-969
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• 2017

The interest in social regulation and its influence on innovation are increasing as the society concerns more for environment and safety. There have been plenty of literature about the impact of social regulation on innovation and its mechanism. Majority of research have been influenced by or based on the famous Porter's hypothesis. However, majority of the literature focus on internal factors such as expected benefits from change of regulations, and it is hard to find one studying social regulation's influence on innovation through external factors such as market or industrial structure. This study addresses this issue of the impact of social regulation on innovation by analyzing the case of fire-retardant coating material for steel structure industry in Korea. It scrutinizes the impact of social regulation which affects competition and innovation on substitute competing market, and tries to reveal that there might exist the other path to innovation, besides the way that the expected benefit from compliance of regulation directly drives innovation. As a result of the case study, we have found that changes in social regulation may act like economic regulation and restructure the market segment and this effect may lead to innovation. It can be explained by the fact that expected benefits from compliance of regulation can be a direct source of innovation, as Porter suggested, but the change of industry structure and competitive strength caused by the change in social regulation can also act as a driving force of innovation.

• 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.

• Korean Journal of Environmental Agriculture
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• v.8 no.2
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• pp.142-147
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• 1989

In this report, we set up a simple device which enabled us to obtain data useful to estimate the relative capacity of thermal energy retention of greenhouse built with various plastic coverings. A box($20cm{\times}20cm{\times}30cm$) framed with flexiglass at the edges and covered with thin plastic films was made, in which were placed a thermostat-controlled nichrom wire heater and a thermal probe made of thermister to monitor temperature changes. A wheaston-bridge type transducer and a chart recorder were used to record the changes of temperature inside the box The data obtained by using the device showed that the relative rate of heat toss through plastic films with identical thickness decreased in the order of PE film>EVA film>PVC film and that IR additives such as fine silica gel improved the insulating power of plastic films. This observations are in well accord with general information, demostrating the feasibility of the device in usefulness for the purpose of screening of various commercial plastic coverings.