• 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.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.330-339
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• 2014

Growth and anthocyanins of lettuce (Lactuca sativa L., 'Mid-season') grown under LED lamps with blue light in the range of 430-470 nm or with red light in the range of 630-670 nm were analyzed in this study. Cool-white fluorescent light was used a s the control. P hotosynthetic photon flux, p hotoperiod, air temperature, relative humidity, and $CO_2$ concentration in a closed plant production system were $201{\pm}2\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 16/8 hours (day/night), $22/18^{\circ}C$, 70%, and $400{\mu}mol{\cdot}mol^{-1}$, respectively. At 21 days after light quality treatment, growth characteristics and anthocyanins content of lettuce as affected by the peak wavelength of blue or red LED were significantly different. Among peak wavelengths treated in this stusy, R1 treatment (peak wavelength 634 nm) and R6 treatment (peak wavelength 659 nm) were effective for increasing leaf width, leaf area, shoot fresh weight, and photosynthetic rate of lettuce. B5 treatment (peak wavelength 450 nm) and B4 treatment (peak wavelength 446 nm) increased the anthocyanins concentration and chlorophyll content in lettuce leaves, respectively. Anthocyanins in lettuce leaves increased linearly with decreasing hue value of leaf color and with increasing SPAD value of lettuce leaves. From these results, it was concluded that the red LED with peak wavelengths of 634 nm and 659 nm and the blue LED with peak wavelengths of 450 nm can be used as potential light spectra for increasing the yield and anthocyanins accumulation of leafy vegetable.

• 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.

• Journal of Korean Society of Forest Science
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• v.84 no.3
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• pp.306-318
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• 1995

To investigate the effect of low light intensities and the inoculation of Frankia and/or Alpova diplophloeus on the symbioses development and their host growth, red alder(Alnus rubra Bong.) seedlings were grown in an air - filtered walk - in growth chamber with either $N_2$ - fixing Frankia inoculation or N - fertilization and live or dead spore inoculation of the ectomycorrhizal fungus A. diplophloeus(Zeller & Dodge) Trappe & Smith. When they were 20 weeks old, the seedlings were grown under three levels of light intensities of 680, 320 and $220{\mu}mol/m^2/s$ PPFD(photosynthetic photon flux density) for three weeks. PPFD of 220 significantly decreased the development of A. diplophloeus mycorrhizae and nodules, the rates of $N_2$ - fixation and $CO_2$ exchange, and the growth of tile seedlings. PPFD 320 significantly decreased the $CO_2$ exchange rate only. Frankia inoculation significantly increased mycorrhiza formation and seedling growth. Alpova inoculation significantly increased seedling growth but not nodule development and $N_2$ - fixation. None of the symbionts affected $CO_2$ exchange rates. Frankia was more critical for seedling growth and mycorrhizal development than the mycorrhizal fungus for seedling growth and nodule development.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.105-109
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• 2020

This study was conducted to the improvement of solar light-based artificial light supply system and effect of lettuce cultivation. The artificial light supply system was consisted of units such as light source, power, system measurement and controller. The light source supply was composed of a solar transmitter and an LED lamp. The power supply consisted of an leakage breaker, SMPS, LED controller and relay. The solar transmitter was made of a quartz optical fiber with optimal light transmission. Artificial light used white lamp among LEDs. System measurement and control consisted of touch screen, Zigbee communication module and light quantity sensor. The results of test confirmed that the LED light is automatically activated when the intensity measured by the light intensity sensor is 200 μmolm^-2s^-1 or less. Moreover, the leaf length, root length, chlorophyll content and root fresh weight of optical fiber treatment was hight than LED lamp treatment. Therefore, it can be inferred that the energy-saving solar light collector device can be effective in the indoor lettuce production. However, the use of LED lamp is also recommended to assure the availability of sufficient sunlight in cloudy and rainy days.

• Korean Journal of Environmental Agriculture
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• v.38 no.1
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• pp.61-67
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• 2019

BACKGROUND: Many studies on artificial lighting have been recently performed to investigate its effect on agricultural products with good quality. This review was aimed at comparing the effects of artificial light on functional metabolites of the plants that were grown in greenhouses and growth chamber. METHODS AND RESULTS: It has been summarized that artificial lighting both in growth chambers and greenhouses caused different functional metabolites patterns depending on light quality. Even though the same light quality was applied, different patterns in metabolites were observed in different plant species. For the same species, supplementation of the same light quality in both growth chambers and greenhouses did cause different functional metabolites patterns. CONCLUSION: Artificial lighting caused different patterns in functional metabolites of plants grown in greenhouses and growth chambers, depending on the light quality and/or plant species. The manipulation of plant growth and functional metabolites would be possible by engineering the light qualities, but knowledge on proper lighting condition depending on plant species and growth places would be necessary.

• 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.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.127-127
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• 2003

Haptophyta(이하 하프토조로 표기)는 그 일부종이 toxin을 가지며, 더욱이 이들 종들이 원인 생물로 발생하는 bloom으로 인한 경제적 피해 발생 등으로 인해 최근 여러 나라에서 활발한 연구가 이루어지고 있다. 남해안 일대의 몇몇 어ㆍ패류 양식장에서 이용하고 있는 식물먹이생물 및 동물먹이생물의 배양수조 내에서 배양을 목적으로 하는 먹이생물 이외의 혼재 생물의 종류를 조사하던 중 Haptophyta의 Prymnesium속 생물이 혼재하고 있는 것을 발견하였으며, 혼재된 Prymnesium은 양식 패류의 인공 종묘 생산 과정에서 사육 치패의 먹이로 이용되는 식물먹이생물 Isochrysis galbana의 증식을 크게 억제하였고, 더욱이 Prymnesium이 혼재된 Isochrysis galbana를 인공 종묘생산 중이던 치패에 투이한 결과 치패 모두가 폐사에 이르는 것을 관찰하였다. 이에 Isochrysis galbana의 배양 수조내에 Prymnesium이 혼입 하였을 경우 Isochrysis galbana의 증식양상을 알아보기 위해, Isochrysis galbana의 세포밀도를 5,440,000cells/ml로 하고 Prymnesium의 세포밀도를 10,000cells/ml로 하여 혼합 배양한 결과 배양개시 1일 후의 각 세포밀도는 Isochrysis galbana가 1,040,000cells/ml로 급격히 저하하였으며, 이와는 달리 Prymnesium은 50,000cells/ml로 증가하였다. 이들 종 각각의 증가 및 감소추세는 계속되어 배양개시 5일 후에는 Isochrysis galbana가 530,000cells/ml로 처음 배양당시 세포수의 90% 이상 감소하였고, Prymnesium은 43,333cells/ml로 4배 이상 증가하였다. 이 실험에서 Isochrysis galana의 세포수가 감소하는 이유는 정확히 알 수는 없으나, 하프토조의 일부 종에서는 광합성을 통한 유기물합성 이외에도 외부로부터의 DOC(dissolved organic carbon)를 직접 배양수로부터 취하거나 또는 영양염 제한 조건에서는 food particle을 섭취하는 경우가 있는 것으로 보고되고 있다. 한편, 이들 Haptopyta가 양식장에서 이용되어지는 해수를 통해 유입되는지를 알아보기 위해 모래여과조를 통과한 해수를 플랑크톤 배양용 배지의 첨가 없이 배양한 결과, Haptophyta의 Prymnesium, Chrysochromulina 및 Phaeocystis 둥의 수 종이 출현하였으며, 일부 종의 경우는 일정기간 지속적으로 배양되어짐을 알 수 있었다.

• Korean Journal of Remote Sensing
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• v.28 no.4
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• pp.435-448
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• 2012

Evapotranspiration (ET) including evaporation from a land surface and transpiration from photosynthesis of vegetation is a sensitive hydrological factor with outer circumstances. Though both direct measurements with an evaporation pan and a lysimeter, and empirical methods using eddy covariance technique and the Bowen ratio have been widely used to observe ET accurately, they have a limitation that the observation can stand for the exact site, not for an area. In this study, remote sensing technique is adopted to compensate the limitation of ground observation using the Moderate Resolution Imaging Spectroradiometer (MODIS) multispectral sensor mounted on Terra satellite. We improved to evapotranspiration model based on remote sensing (Mu et al., 2007) and estimated Penman-Monteith evapotranspiration considering regional characteristics of Korea that was using only MODIS product. We validated evapotranspiration of Sulma (SMK)/Cheongmi (CFK) flux tower observation and calculation. The results showed high correlation coefficient as 0.69 and 0.74.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.1-10
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• 2006

This study was carried out to develope new zoysiagrass cultivar 'Millock'(Patent registration No. : 10-2005-0110051). Artificial selfing of collected line of MJ8 was conducted to develope F1 plant (MJ8S). Among the inbred progenies, MJ8S-9 (Millock) showed superior performance in color, density, and rust resistance. 'Millock' showed genetically dark green color, with medium-textured leaf ($4.2{\pm}0.44$ mm), short internode length ($3.5{\pm}0.28$ cm), and wide leaf angle ($52.5{\pm}10.8$ degree). Height to the lowest leaf blade of this cultivar was $1.9{\pm}0.91$ cm, which may allow low mowing height. 'Millock' has a yellowish green stolen. Also, specific bands with primer number OPB 8 by RAPD analysis can be used for a cultivar identification.