• 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)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.04a
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• pp.20-24
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• 2002

농산물은 기후와 시장동향에 따라 물량, 품질, 가격이 변동하고 산지에 따라 상품규격이나 품종이 다양하기 때문에 적기에 수출물량을 공급하고 지속적으로 확보하는 것이 어려운 문제로 대두되고 있다. 따라서 앞으로 농산물의 국제 경쟁력은 상품의 고품질화와 시장의 변화에 따른 상품의 안정적 공급에 달려 있다고 할 것이다. 연구결과에 의하면 작물이 안정적으로 생장하고 고품질의 수확물을 지속적으로 생산하기 위해서는 적정 일일적산 광합성유효광양자속을 균일하게 공급할수 있어야한다. (중략)

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.314-320
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• 2014

Three leaf vegetables, namely green lettuce, red lettuce (Lactuca sativa) and red-veined chicory (Cichorium intybus) were grown in minigreenhouses covered with two new functional films and conventional polyethylene film (PE). Seedlings of leaf vegetables were transplanted in a plastic troughs filled with soil-perlite mixture. Two functional films were made from polyolefin (PO) material. Measurement of optical characteristics showed that polyolefin films have better transmittance for the photosynthetic active radiation (PAR, 400-700nm) and higher absorptance for the ultraviolet radiation (UV, 300-400nm) in comparison with the conventional PE film. After three months of utilization higher loss in PAR transmittance was observed for conventional PE film. Leaf vegetables growth was enhanced and yield was increased in greenhouses covered by new functional films.

• 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.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.495-496
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• 2001

저서 해조류의 수직분포에 대한 광의 영향은 주로 유효 광에 대한 종간의 상이한 반응의 결과에 의한다. 특히 조하대의 Kelp군집의 형성은 배우체나 어린 포자체와 같은 부착단계에 있어서의 서식처의 광조건에 의해 중요하게 영향을 받는다(Luning, 1981; Drew, 1983). 이것은 광이 이들의 광합성의 에너지원으로써, 광량, 광질, 광주기의 변화가 조류의 생장을 시ㆍ공간적으로 제한하고 있기 때문이다. (중략)

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.144-151
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• 2020

Agrivoltaic systems (AVS) is defined as combining farm-grown crops with photovoltaic panels (PV) installed several meters above the ground. Solar radiation (W/㎡), photosynthetic photon flux density (PPFD, µmol/㎡/s), air temperature (℃), vapor pressure (kPa), soil moisture (㎥/㎥), soil temperature (℃), wind direction (˚), and wind speed (m/s) were measured under the AVS in Boseong-gun during winter barley season. Data was collected by 5 minute interval. All data can download at Github site (https://github.com/chojaeil/AVS_Boseung). To gap-filling missing solar radiation data during about two weeks, the conversion coefficient from solar radiation to PPFD was estimated as 0.41. Further, according to the ratio of diffuse radiation to direct radiation, the maximum value among the twenty PPFD sensors under the AVS was related to the PPFD value of filed.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.400-406
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• 2018

In this experiment the effect of supplemental lighting on the growth and yield of cucumber (Cucumis sativus L. 'Fresh') plants during low radiation period of winter season were investigated in glasshouses using common high-pressure sodium (HPS) lamps and newly developed plasma lighting system (PLS) lamps. Plants grown without supplemental lighting were considered as a control. Supplemental lighting was provided from November 20th, 2015 to March 15th, 2016 to ensure 14-hour photoperiod (natural+supplemental light), also lamps were operated automatically when the outside sun radiation levels were less than $100W{\cdot}m^{-2}$. Spectral analysis showed that HPS lamp had a discrete spectrum, lacked of the radiation in the 400-550 nm wave band (blue-green light), but had a high output in the orange-red region (550-650 nm). A higher red light output resulted in an increased red to far-red (R/FR) ratio in HPS lamp. PLS had a continuous spectrum and had a peak radiation in green region (490-550 nm). HPS has 12.6% lower output in photosynthetically active radiation (PAR) but 12.6% higher output in near infra-red (NIR) spectral regions compared to PLS. Both HPS and PLS lamps emitted very low levels of ultra-violet radiation (300-400 nm). Supplemental lighting both from HPS and PLS lamps increased plant height, leaf number, internode number and dry weight of cucumber plants compared to control. Photosynthetic activity of cucumber plants grown under two supplemental lighting systems was comparable. Number of fruits per cucumber plant (fruit weight per plant) in control, PLS, and HPS plots were 21.2 (2.9 kg), 38.7 (5.5 kg), and 40.4 (5.6 kg), respectively, thereby increasing yield by 1.8-1.9 times in comparison with control. An analysis of the economic feasibility of supplemental lighting in cucumber cultivation showed that considering lamp installation and electricity costs the income from supplemental lighting increased by 37% and 62% for PLS and HPS lamps, respectively.

• Korean Journal of Medicinal Crop Science
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• v.14 no.4
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• pp.244-249
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• 2006

This study was carried out to determine leaf photosynthetic capacity and growth characteristics of Kalopanax picturs Nakai seedlings under the different light condition. The seedlings grown under low light condition showed larger leaf area and petiole, and higher relative growth rate than those grown under high light condition. Chlorophyll contents as chlorophyll a, chlorophyll b, and chlorophyll a + b were high in the seedlings grown under highlight condition compared to those grown in low light conditions. The mean absorption value of shade leaf within photosynthetically active radiation (400-700 nm) was slightly higher than that of sun leaf, Leaf photosynthetic capacity of seedling was variable under the different light conditions. Seedling grown under high light condition had the higher photosynthetic capacity. Leaf photosynthetic rates under forestry and nursery were 700 and $300\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. However, leaf photosynthetic rates under high and low light conditions were 500 and $300\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively.

• 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.