• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.16-18
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• 2012

LED lighting systems that combine lighting capability, emotional and physiological characteristics are required for lighting source and multifunctional applications. In this work, Simulation studies using optical analysis software packages, Light Tools, are presented. This is done to estimate the uniformity ratio of illuminance and photosynthetic photon flux density (PPFD) of the periodic 2D lattice arrangements, such as square, diamond, two-way bias quadrangular, hexagonal, and Kagome lattices, under the same transmissivity, absorptance and reflectivity. It has been found out that the two-dimensional Kagome lattice arrangement exhibited high uniformity ratio of illuminance and PPFD compared to other lattices. Accordingly, these results can be used to guide a design and improve the lighting environment which in turn would maximize the uniform distributions of illuminance.

• Korean Journal of Plant Resources
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• v.21 no.4
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• pp.299-303
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• 2008

Two-year-old seedlings of Ilex rotunda were grown under control (full sunlight) and three different shading condition. Those conditions were full sunlight (PPFD 1600${\mu}mol\;m^{-2}\;s^{-1}$), 30% (PPFD 400${\mu}mol\;m^{-2}\;s^{-1}$), 50% (PPFD 250${\mu}mol\;m^{-2}\;s^{-1}$) and 70% treatment (PPFD 100${\mu}mol\;m^{-2}\;s^{-1}$). Total chlorophyll contents were inverse proportion to light intensity. Seedlings under full sunlight showed the highest photosynthetic activity such as photosynthetic rate, intercellular $CO_2$ concentration and water use efficiency. Photosynthetic activity trend was increased at the higher light intensity than the lower treatment over PPFD 500${\mu}mol\;m^{-2}\;s^{-1}$. Especially, seedlings under 70% treatment showed the worst photosynthetic activity at high light intensity. That result was regular for adapted plant in low intensity environment. Leaf area was also inverse proportion to light intensity, while dry weight per leaf area was shown the opposite trend.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.361-365
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• 2013

To investigate factors determining peach fruit quality, chlorophyll content by leaf positions, chlorophyll content of foliated leaf, change of leaf area, and photosynthetic capacity were monitored. Photosynthetic rate in response to radiation intensity and $CO_2$ concentration, and change of sucrose content after shading treatment also were investigated. Chlorophyll content was similar in $5-12^{th}$ leaves after 10 days of foliation, while young $13-16^{th}$ leaves showed lower chlorophyll contents. Chlorophyll content was 2.56 ${\mu}g/cm^2$ on May $28^{th}$, just after foliation, and rapidly increased up to 6.35 ${\mu}g/cm^2$ on June $12^{th}$. After this point, chlorophyll content gradually increased during two months showing the highest value of 9.03 ${\mu}g/cm^2$ on August $14^{th}$. Leaf area was 27.1 $cm^2$ just after foliation and 37.7 $cm^2$ on $10^{th}$ day of foliation increasing 10.6 $cm^2$ during 10 days. Leaf area slowly increased by 3.9 $cm^2$ during next one month. Photosynthetic capacity increased rapidly until the $30^{th}$ day of foliation showing the highest capacity of 13.8 ${\mu}mol/m^{-2}/sec^{-1}$. After this point, photosynthetic capacity decreased sharply. Photosynthetic rate in response to radiation intensity increased rapidly until the PPFD reached to 600 ${\mu}mol/m^{-2}/sec^{-1}$ and increased gradually from 600 ${\mu}mol/m^{-2}/sec^{-1}$ to 1200 ${\mu}mol/m^{-2}/sec^{-1}$ of PPFD and stayed stable beyond this point. Photosynthetic rate in response to $CO_2$ concentration increased until 600 ppm of $CO_2$. At higher $CO_2$ concentration, photosynthetic rate stayed stable or decreased. Sucrose content in leaves was not significantly different between control and shading group until one hour of shading treatment while decreased in shading group after two hours of treatment.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.928-936
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• 2010

This study was conducted to select efficient foliage plants for improving indoor environment conditions through the investigation of physiological responses including photosynthetic rate according to temperature, light intensity, and $CO_2$ level. Eight popular foliage plants used in this study were $Hedera$ $helix$ L., $Cissus$ $rhombifolia$ Vahl, $Ficus$ $benjamina$ L. 'Hawaii', $Syngonium$ $podophyllum$ Schott 'Albo-Virens', $Dieffenbachia$ $sp.$ 'Marrianne', $Pachira$ $aquatica$ Aubl., $Spathiphyllum$ $wallisii$ Regel, and $Scindapsus$ $aureus$ Engler. Photosynthetic rate and transpiration rate of the plants subjected to various light intensities (0, 25, 50, 75, 100, 150, 300, and $600{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD), $CO_2$ levels (0, 50, 100, 200, 400, 700, and $1,000{\mu}molCO_2{\cdot}mol^{-1}$), and two different temperatures (16 and $22^{\circ}C$) were measured. In addition, various parameters in relation to photosynthesis were calculated from the measured data. As a result, the patterns of photosynthesis varied among 8 foliage plants according to light intensity, $CO_2$ level, and temperature. Most foliage plants except $Dieffenbachia$ had high levels of apparent quantum yield, which represents the photosynthetic rate under low light intensity (PPFD $0-100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). $Hedera$ $helix$, $Ficus$ $benjamina$, $Pachira$ $aquatica$, and $Spathiphyllum$ $wallisii$ exposed to high light intensity (PPFD $200-600{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed high levels of photosynthesis. $Cissus$ $rhombifolia$ and $Syngonium$ $podophyllum$ were low in $CO_2$ fixation efficiency compared to the other 6 foliage indoor plants. $Hedera$ $helix$ and $Spathiphyllum$ $wallisii$ showed high photosynthetic rate under high $CO_2$ level and vigorous photosynthesis was also observed in $Ficus$ $benjamina$ and $Pachira$ $aquatica$ grown under $22^{\circ}C$. Considering characteristics of indoor environment such as low light, high $CO_2$ level, and low relative humidity, therefore, $Hedera$ $helix$, $Spathiphyllum$ $wallisii$, $Ficus$ $benjamina$, and $Pachira$ $aquatica$ were efficient indoor foliage plants to improve indoor environmental conditions.

• Journal of Korean Society of Forest Science
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• v.90 no.4
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• pp.476-487
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• 2001

In this study, three tree species (Populus euramericana, Kalopanax pictus and Quercus serrata) exhibiting different levels of shade tolerance were employed to investigate photosynthetic responses to the lower light condition on forest floors. Chlorophyll contents, spectral properties and photosynthetic characteristics were examined by using the tree species grown under high light intensity (PPFD $920{\mu}mol\;m^{-2}s^{-1}$) or low light intensity (PPFD $80{\mu}mol\;m^{-2}s^{-1}$). Plants grown under the low light intensity tended to have reduced leaf area, chlorophyll content per unit leaf area, light absorption and respiration in the shade intolerant tree species of P. euramericana. However, the shade tolerant species K. pictus and Q. serrata showed increased leaf area, chlorophyll content and net apparent quantum yield. Therefore, light absorption and light utilization efficiency were improved under the low light intensity. Also shade tolerant species maintained activities of photosystems and $CO_2$ fixation systems with little changes in low light intensity condition.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.294-301
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• 2016

This study was conducted to analyze the seedling quality of korean melon and the growth after transplanting of korean melon nursed under the LED sources. LED sources were RB7 (Red:Blue=14:2), RB3 (Red:Blue=12:4) and Blue(B=16). Photosynthetic photon flux density(PPFD) was 50, 100 and $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The lighting treatment was started after graft-taken and was applied for 20 days at 4 hours(05:30 and 07:30, 17:30 and 19:30) per day. Plant height and stem diameter of scion were longer and thicker under a high ratio of blue light condition. Dry matter ratio and compactness were highest in RB3 compared to the other LED sources treatments. $CO_2$ exchange rate increased $5.44{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$ under RB7 $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and dropped to negative values under control. PPFD $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of RB3 resulted in the longest plant height by 132.3cm and flowering ratio also was the highest by 75%.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.328-333
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• 2006

This study was conducted to find the characteristics of photosynthesis, leaf and fruit by crown layers in Rubus coreanus Miq. Light compensation points were shown PPFD 33, 20 and $5{\mu}mol\;m^{-2}\;S^{-1}$ at upper, middle and lower layer, respectively. Light saturation points were appeared PPFD 1000, 500 and 200 and their net photosynthesis rate were 8.52, 5.25 and $3.60{\mu}mol\;CO_2\;m^{-2}S^{-1}$ at upper, middle and lower layer, respectively. Uiryeong 7 which was viny type showed higher net photosynthetic rate than others at upper layer. Songgye 6 which was upright type showed lower net photosynthetic rate than others at lower layer. Chlorophyll contents of middle layer had the highest value in the all layers and upper layer showed the lowest value. Most characteristics of leaf morphology were showed that middle and lower layer had higher value than upper layer. That trend was contrary to characteristics of photosynthesis by crown layers. However, dry weight per leaf area and most characteristics of fruit had the highest value at upper layer and that was similar to characteristics of photosynthesis by crown layers. Also, sugar contents of fruit showed the highest value at middle layer.

• Korean Journal of Environment and Ecology
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• v.26 no.1
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• pp.82-90
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• 2012

In this study, we investigated the environmental factors and growth characteristics of Sasa borealis community inside a temperate deciduous forest and reviewed its effect on the lower vegetation and natural regeneration. The S. borealis community in the Jungsan-ri region of Jirisan National Park was chosen as the study area, and the vegetation and the environmental factors were investigated. The dominance value, height and foliage layer thickness were investigated as the growth characteristics of S. borealis in the area. As the environmental factors, we investigated the photosynthesis photon flux density (PPFD) of the shrub and ground layers as well as the chemical characteristics of the soil. Additionally, we investigated the flora on the ground layer of the area as well as the number and height of woody plants. The result showed that the height and foliage layer thickness of the S. borealis was closely related to the light conditions but the distribution was not determined simply by the effect of the environment or vegetation of the particular area. This may be deeply related with the unique survival strategy of S. borealis, a vegetably propagated plant, that it can extensively distributed on a heterogeneous resources environment in a forest as multiple culm are interconnected with each other through the rhizomes. The dense dominance and great height of S. borealis reduced the plant species diversity in the ground layer by decreasing the PPFD on the ground surface.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.387-393
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• 2011

This study was conducted to find the effects of microclimates such as air and soil temperature, photosynthetic photon flux density (PPFD) on the berry development and physiological property between cultivation conditions (open field and rain shelter house) in 'Northland' blueberries (Vaccinium corymbosum). The rate of berry growth and development was stimulated in plants grown in rain shelter house, thus, berry reached to the ripe stage about one week earlier than those in open field. Berry weight and size at ripe stage seemed not affected by microclimates. However, total soluble solids content was higher in berries from open field whereas the titratable acidity was significantly higher in berries grown in rain shelter house. Berry firmness at ripe stage was little affected by growing condition. Total anthocyanin content of ripe berries was higher in berries harvested from rain shelter house. Total phenolics content and anti-oxidation activity of berries were higher in open field than those of rain shelter house during berry development but no differences were found at ripe berries.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.61-67
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• 2006

We examined seedlings of two species (Ilex rotunda and Illicium anisatum) which have a different level of shade tolerance and raised them under different light regimes (full sunlight and 50% shading). After 12 months, we investigated chlorophyll content (Chl. a, Chl. b and Chl. a+b), photosynthetic systems (photosynthetic rate, light compensation point, dark respiration rate and quantum yield), intercellular $CO_2$ concentration and water use efficiency to show acclimation reaction to different light conditions. Seedlings grown under full sunlight showed lower chlorophyll content than those in the shading regime. There was a significant difference between the full sunlight and shade treatments in I. anisatum (shade tolerance species). I. rotunda (intermediate species) showed high photosynthetic rate and water use efficiency over PPFD $1000\;{\mu}mol\;m^{-2}s^{-1}$ to full sunlight. Also, I. anisatum grown under full sunlight showed lower photosynthetic rate and water use efficiency over a range of all PPFD. This result showed that I. rotunda has a more flexible reaction system than that of I. anisatum.