• Journal of Bio-Environment Control
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• v.11 no.2
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• pp.56-60
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• 2002

Since the transmittance of solar radiation directly affected by the structural frames of greenhouse can be changed according to the ratio of diffuse to direct radiations, it is necessary to investigate the transmittance of greenhouse at the different weather conditions. We can easily get the data of total solar radiation from the Meteorological Administration, but we have to personally measure the photosynthetic photon flux (PPF). If the relationship between total solar radiation and PPF is established, the PPF can be simply acquired from the relationship. Sol it is required to develop the equation to calculate PPF depending on weather condition. This study was conducted to determine the transmittance of PPF at canopy level in glasshouse and the correlation between total solar radiation and PPF at clear and cloudy days. The variation phase of greenhouse transmittance at clear day was very different from that at cloudy day. It was concluded that the proper transmittance, depending on the weather condition, should be adopted to calculate the accurate total solar radiation and PPF in greenhouse. The transmittance of solar radiation was the same as that of PPF in greenhouse. It was confirmed that the ratio of PPF to total radiation increased as the amount of cloud increased. The correlation between the hourly total solar radiation and PPF was derived.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2000.10b
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• pp.19-22
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• 2000

접목을 실시할 때 접수와 대목의 적정한 생육은 접목을 용이하게 할 뿐만 아니라 활착 후 접목묘의 묘소질 지속에도 커다란 영향을 미칠 수 있다. 자연광 조건에서 육묘를 실시하면 묘의 생육이 불균일하여 묘소질이 일정치 않게 된다. 그러므로 인공광을 이용한 폐쇄된 환경 조건에서 육묘가 바람직하나, 대목용 박에 대한 적정 광합성 유효광량자속 또는 광주기가 제시되지 않고 있다. 본 연구의 목적은 대목용 박의 초기 생육에 미치는 광합성 유효광량자속과 광주기의 영향을 구명하는 데 있다. (중략)

• 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.1
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• pp.40-44
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• 2002

A prototype of closed-type transplant production system(CTTPS) with fully environmental control was developed to produce massively quality transplants. Four photosynthetic photon flux(PPF) levels of 200,300,400 and 500$\mu$mol . m$^{-2}$ .s$^{-1}$ , four photoperiod levels of 1816 h,12/12h, 9/15 h and 6/18 h were provided to analyze the growth and development of cucumber plug seedlings(Cucumis sativus L., cv. Kyuewosalichungiang) as affected by PPF and photoperiod in a CTTPS. Effect of photoperiod on the growth and development of cucumber plug seedlings produced in a CTTPS was higher than PPF, Stem diameters dry weight of shoot and roots number of leaves, leaf with and length, and SPAD value of cucumber plug seedlings produced in a CTTPS were significantly high as compared to the control. But stem length of plug seedlings produced in a CTTPS was shorter than those of the control. Growth characteristics of cucumber plug seedlings raised at photoperiod of 6/18 h and PPF of 200$\mu$mol . m$^{-2}$ .s$^{-1}$ were similar to the those of the control. These results suggest that cucumber quality transplant can be produced at relatively short photoperiod and low PPF, It means that the electric energy consumed for the production of cucumber plug seedlings in a CTTPS can be saved.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.535-539
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• 2010

The formation and elongation of runners, growth of runner plants, and transplant propagation rates of 'Maehyang' strawberry were investigated at various photosynthetic photon flux (PPF) levels. Strawberry plants having $3.1{\pm}0.4$ leaves and $7.0{\pm}1.1mm$ of crown diameter were used as propagules and were cultured for 35 days in 9 transplant production modules using fluorescent lamps as artificial lighting sources. Applied PPF levels were $137.4{\pm}2.1$, $217.0{\pm}1.0$, and $274.7{\pm}8.4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as measured on the surfaces of empty shelves. The numbers of runners and runner plants per propagule were the greatest at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPF. The runner plant propagation rate was 0.27 plant/day/propagule at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, which was significantly greater than that of conventional propagation methods. Results indicate that high PPF levels promotes the formation of runners and runner plants of strawberry and that the rapid propagation method with high PPF levels can be feasible for production of vigorous transplants in a closed transplant production system.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.11a
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• pp.40-45
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• 2001

최근 들어 육묘시설의 양적 증가와 육묘 기술 수준의 향상에 힘입어 플러그묘의 보급이 확대되고 있다. 더구나 육묘와 재배의 분업화가 진행되고, 고품질 묘의 안정된 수급이 대한 관심이 늘어나면서 육묘 산업에 대한 비중이 점차 증가하고 있다. 국내에 설치되어 있는 모든 육묘시설은 개방형 묘생산 시스템으로서, 육묘시설 내의 환경이 외부 기상 조건과 밀접한 관계를 이루며 변화하는 특성을 갖는다. (중략)

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.45-53
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• 2003

The object of this study was to develop the control technology of daily integral photosynthetic photon flux (PPF) by the artificial lighting and shading screen in greenhouse. The shading time needed to get the target PPF by using two types of shading screens having shading ratio of 55% and 85% was analyzed. The results showed the shading ratio of screen to be installed in greenhouse should be different depending on the amount of target PPF to be controlled. The PPF control experiment by using the 55% shading screen in July and August showed that the maximum difference between measured and calculated value was about 5 mol$.$ $m^{-2}$ $.$ $d^{-1}$ in no shading condition. This difference is satisfactory result because the daily integral PPF is quite different depending on the weather condition. The simulation result about PPF distribution pattern shortened the time needed to find the proper arrangement of artificial lightings in greenhouse. But the further study was required to find the supplemental lighting arrangement to be able to provide the exactly uniform distribution of target light intensity. The supplemental irradiation time needed to acquire the target daily integral PPF for different supplemental light intensities, weather conditions, and months was analyzed. The result showed that the supplemental light intensity should be decided depending on the amount of target PPF to be controlled. The result of PPF control experiment conducted by using 55% shading screen and 300 $\mu$mol$.$ $m^{-2}$ $.$ $s^{-1}$ supplemental light intensity from the end of May to the beginning of June showed that the maximum difference between target and measured value was about 3 mol$.$ $d^{-1}$ $.$ $m^{-2}$ . If we consider that the difference of the daily integral PPF depending on weather condition was the maximum 30 mol$.$ $m^{-2}$ $.$ $d^{-l}$, the control effect was acceptable. Although the result of this study was the PPF control technology to grow lettuce, the data and control method obtained could be employed for other crop production.n.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.231-238
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• 2018

Chlorophyll fluorescence, chlorophyll content, graft-taking and growth of grafted cucumber seedlings as affected by photosynthetic photon flux (PPF) of LED lamps were analyzed in this study. Four PPF levels, namely 25, 50, 100, $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ were provided to investigate the effect of light intensity on the chlorophyll fluorescence, chlorophyll content, graft-taking and growth of grafted cucumber seedlings. Air temperature, relative humidity, and photoperiod for graft-taking were maintained at $25^{\circ}C$, 90%, $16h{\cdot}d^{-1}$, respectively. Maximum quantum yield (Fv/Fm) of rootstock as affected by PPF was found to be 0.84-0.85 and there was no significant change in Fv/Fm. Even though Fv/Fm of scion measured at 2 days after grafting was lowered to 0.81-0.82, after then it gradually increased with increasing PPF. At 4 days after grafting, the chlorophyll content extracted from scion increased with increasing PPF. Graft-taking ratio of grafted cucumber seedlings was 90-95% as PPF was ranged from $25{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ to $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. However, the graft-taking ratio of grafted seedlings healed under PPF of $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was decreased to 80%. Maximum PPF measured required for smooth joining of rootstock and scion was assumed to be $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. At healing stage of grafted cucumber seedlings, Fv/Fm of scion decreased and at least two days after grafting were required for rooting of grafted seedlings. Chlorophyll fluorescence response of rootstock and scion was linked to light irradiation. Therefore, it was concluded that physical environment including light and humidity during healing process of grafted seedlings should be controlled more precisely to facilitate root formation and to prevent scion from lowering Fv/Fm. Further studies are required to investigate the effects of root development and joining of vascular bundles of grafted seedlings on the chlorophyll content of scion.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.704-707
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• 2011

본 논문은 ZigBee 기반의 통합센서 네트워크 구축 및 모니터링 시스템 구현을 통해 계절과 시각, 그리고 천기상태에 따라 변화하는 태양광의 광합성유효광량자속밀도를 태양광병용형 식물공장 내부의 각 영역별로 측정 및 분석하고자 한다. 통합센서를 통해 수집된 정보는 식물의 생육에 필요한 적정 태양광 에너지가 유입되는 시간대와 보광을 필요로 하는 시간대 및 그 양을 파악하는데 활용되며, 이를 통해 조명 및 냉난방 기기를 지능적으로 제어함으로써 전체 에너지 소비를 절감하고자 한다.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.253-257
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• 2011

This study was carried out to investigate the effect of different light emitting diode (LED) irradiation on the growth of paprika (Capsicum annuum 'Cupra'). The plants were irradiated by red (660 nm), blue (460 nm) and red + blue (4 : 1) light emitting diodes above 50 cm for 5 hours after sunset. Photosynthetic photon flux (PPF) irradiated by red, blue and red + blue LED were $79{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $75{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and $102{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ respectively. Leaf temperature of paprika grown under blue LED irradiation was the highest of $18.6^{\circ}C$. Fruit temperature was the highest under in the control (no irradiation) but it was lower than leaf temperature. There was influence of LED irradiation on the paprika plants height; under blue irradiation the plant height was the shortest, while under in the control plant height was the highest. The leaf size of under different LED irradiation was bigger than that of in the control. Mean fruit weight under different LED irradiation was significantly increased; however number of fruits and marketable yield per plant were significantly decreased as compared to the control.