• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.38-45
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• 2015

BACKGROUND: For commercial production of greenhouse crops under shorter day length condition, supplementary radiation has been usually achieved by the artificial light source with higher electric consumption such as high-pressure sodium, metal halide, or incandescent lamps. Light-Emitting Diodes (LEDs) with several characteristics, however, have been considered as a novel light source for plant production. Effects of supplementary lighting provided by the artificial light sources on growth of Kale seedlings during shorter day length were discussed in this experiment. METHODS AND RESULTS: Kale seedlings were grown under greenhouse under the three wave lamps (3 W), sodium lamps (Na), and red LEDs (peak at 630 nm) during six months, and leaf growth was observed at intervals of about 30 days after light exposure for 6 hours per day at sunrise and sunset. Photosynthetic photon flux (PPF) of supplementary red LEDs on the plant canopy was maintained at 0.1 (RL), 0.6 (RM), and $1.2(RH){\mu}mol/m^2/s$ PPF. PPF in 3 W and Na treatments was measured at $12{\mu}mol/m^2/s$. Natural light (NL) was considered as a control. Leaf fresh weight of the seedlings was more than 100% increased under the 3 W, Na and RH treatment compared to natural light considering as a conventional condition. Sugar synthesis in Kale leaves was significantly promoted by the RM or RH treatment. Leaf yield per $3.3m^2$ exposed by red LEDs of $1.2{\mu}mol/m^2/s$ PPF was 9% and 16% greater than in 3W or Na with a higher PPF, respectively. CONCLUSION: Growth of the leafy Kale seedlings were significantly affected by the supplementary radiation provided by three wave lamp, sodium lamp, and red LEDs with different light intensities during the shorter day length under greenhouse conditions. From this study, it was suggested that the leaf growth and secondary metabolism of Kale seedlings can be controlled by supplementary radiation using red LEDs of $1.2{\mu}mol/m^2/s$ PPF as well as three wave or sodium lamps in the experiment.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1995.04a
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• pp.79-80
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• 1995

원예작물의 재배에 있어서 인위적인 광질의 조절은 비현실적인 것으로 여겨져 왔으나, 시설피복자재의 발달과 인공광에 의한 보광재배 등은 시설원예에 있어서 광질조절의 가능성을 보여주고 있다. 본 실험은 광질에 따른 미나리의 생육반응을 조사하여 미나리 재배시 광질이용의 기초자료를 얻고자 실시하였다. (중략)

• 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.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.317-325
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• 2011

This study was conducted to examine the effect of supplemental lighting on the growth and yield of hydroponically grown sweet pepper (Capsicum annuum L. cv. sprit) under low levels of natural light in winter. The plants were treated with natural light only (control), 3-hour supplemental lighting before sunrise, after sunrise and after sunset with high pressure sodium (HPS, 400W). As the result of these three treatments, the supplemental lighting promoted photosynthesis in the low light intensity condition and particularly photosynthesis was more active right after sun rise in the morning, 1.5-$3.0{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$ comparing to those of supplemental lighting after sunset, 0.5-$1.5{\mu}molCO_2{\cdot}m^{-2}{\cdot}s^{-1}$. Transpiration rate and stomatal conductance sharply increased with supplemental lighting after sunrise then they decreased again after turning the lights off. Stomatal size was observed $32.2{\mu}m^2$ after supplemental lighting, whereas the size of the natural light was almost closed at $7.7{\mu}m^2$. The average plant height of sweet papper cv. spirit was 185 cm before sunrise, 188 cm after sunrise and 208 cm after sunset with supplemental lighting for 3hours while the control was 171 cm. With supplemental lighting a better number of fruit set per plant was measured 4.3 before and after sunrise, 3.7 after sunset but 2.6 in the control. Interestingly, there were no significant differences in the sugar content ($^{\circ}Brix$) degree between treatment of supplemental lighting, whereas slight differences between seasons were seen. The marketable fruit yield of sweet pepper (cv. spirit) was $116.0kg{\cdot}ha$ with supplemental lighting, whereas the control (natural light only) was $75.8kg{\cdot}ha$. Despite of spending electricity and depreciation cost, the economic analysis showed net income with supplemental lighting after sunrise was 51% higher than control treatment in cv. spirit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1419-1426
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• 2012

The heating and cooling energy load of the KNU plant factory was analyzed using the DesignBuilder. Indoor temperature set-point, LED supplemental lighting schedule, LED heat gain, and type of double skin window were selected as simulation parameters. For the cases without LED supplemental lighting, the proper growth temperature of lettuce $20^{\circ}C$ was selected as indoor temperature set-point together with $15^{\circ}C$ and $25^{\circ}C$. The annual heating and cooling loads which are required to maintain a constant indoor temperature were calculated for all the given temperatures. The cooling load was highest for $15^{\circ}C$ and heating load was highest for $25^{\circ}C$. For the cases with LED supplemental lighting, the heating load was decreased and the cooling load was 6 times higher than the case without LED. In addition, night time lighting schedule gave better result as compared to day time lighting schedule. To investigate the effect of window type on annual energy load, 5 different double skin window types were selected. As the U-value of double skin window decreases, the heating load decreases and the cooling load increases. To optimize the total energy consumption in the plant factory, it is required to set a proper indoor temperature for the selected plantation crop, to select a suitable window type depending on LED heat gain, and to apply passive and active energy saving technology.

• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.226-233
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• 2023

High solar radiation in summer season causes excessive respiration of crops and reduces photosynthesis. In addition, the rainy season, which mainly occurs in summer, causes a low light condition inside the greenhouse. A low light condition can reduce crop growth and yield. This study was conducted to evaluate the effect of shade and supplemental lighting on the growth and yield of cucumber during summer season. Cucumber grafted seedlings were transplanted in two plastic greenhouses on August 30, 2022. To reduce the light intensity inside the greenhouse, a 50% shading screen was installed in one greenhouse. Supplemental lighting was conducted from September 7, 2022 to October 20, 2022. HPS (high-pressure sodium lamp), W LED (white LED, red:green:blue = 5:3:2), and RB LED (combined red and blue LED, red:blue = 7:3) were used for supplemental lighting sources, and non-treated (nonsupplemental lighting) was as the control. The supplemental lighting was conducted before sunrise and after sunset for 2 hours with a photosynthetic photon flux density of 150 ± 20 µmol·m^-2·s^-1. The plant height, leaf length, leaf width, and SPAD value tended to increase in the shading group. RB LED increased stem diameter regardless of shading treatment. Fresh and dry weights of fruits were not significantly different in shading and supplemental lighting. Average fresh weight of fruits was not significantly different among supplemental lighting as the harvest date passed. In conclusion, in this study 50% shade treatment significantly improved the growth of cucumber during the summer season. In addition, the growth and fruit characteristics are better than the control without supplemental lighting. This study can be used as basic research data for applying supplemental lighting technology to cucumber cultivation.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.11a
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• pp.61-65
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• 1997

본 연구에서는 반사필름 멀칭과 북측면의 반사판설치에 의한 보광이 토마토의 광이용에 미치는 영향을 밝히기 위해 토양 및 수경재배를 통해 토마토의 엽온변화, 기공특성, 증산ㆍ광합성속도등의 변화들을 중심으로 검토하였다. 보광 처리에 의해 토마토엽의 기공밀도는 증가하였으나 기공의 크기와 면적은 차이가 없었다. (중략)

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.339-346
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• 1992

Self-and reciprocal-graftings were made between soybean varieties(cv.Hwangkeumkong, Paldalkong, Bokwangkong and Jangkyongkong) to assertain the relative role of shoot and root in soybean growth and yield determination. The influence of grafting per se on plant height and leaf number on main stem were negligible as evidenced by the insignificant differences between self-and reciprocal-graftings. The effect of grafting on flowering was different between different set of varieties grafted reciprocally. Self grafting delayed flowering 2 days and reciprocal grafting delayed another 2 days, in general. The effects of grafting on dry weights of different plant parts except pod were also insignificant. Reciprocal grafting increased pod dry weight in Hwangkeumkong and Paldalkong regardless whether they were used as scion or stock. Reciporcal grafting also influenced dry weights of Bokwangkong and Jangkyongkong significantly, but the response was different from those of Hwangkeumkong or Paldalkong. Jangkyongkong, when used as stock, decreased total dry weight of Bokwangkong significantly through the reduction of pod and stem dry weights. Stem diameter was increased by grafting, however, grafting decreased number of branches in all varieties. The average yields of self-and reciprocal-grafting were decreased by 11% and 24%, respectively, comparing to that of non-grafting, while average yield of reciprocal grafting was 14% lower than that of self grafting. Stem weight of grafted soybeans was decreased by 29-32% comparing to that of non-grafted soybeans, but the difference between self and reciprocal graftings was negligible. The genetic characteristics of scion was found to be more important than those of stock in determination of yield and stem weight. It was also indicated that varieties and characteristics are different in response to grafting.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.204-211
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• 2022

To produce a high quality crop, light is an essential environmental factor in greenhouse cultivation. In the winter season, solar radiation is weak than other season. Therefore, using supplemental light during a low radiation period can increase the crop growth and yield. This study was conducted to select the economical supplemental light source for greenhouse cultivation in pepper during the low radiation period. The green pepper (Capsicum annuum 'Super Cheongyang') was transplanted on 5 September 2019. Supplemental lighting treatment was conducted from 1 January 2020 to 31 March 2020. RB LED (red and blue LED, red:blue = 7:3), W LED (white LED, R:G:B = 5:3:2), and HPS (high-pressure sodium lamp) were used as the supplemental light source. Non-treatment was used as the control. The plant height, SPAD, and number of nodes of pepper plants have no significant differences by supplemental light sources. However, the number of ramifications plants was the greatest in RB LED light source. Moreover, supplemental lighting increased photosynthesis of the pepper plant, and especially, the RB LED had the highest photosynthesis rate during supplemental lighting period. Also, the yield of pepper increased in the supplemental lighting treatment than in the control, and the RB LED had the greatest yield than other light sources. The electricity consumption was the highest in W LED and the lowest in HPS light. Through the economic analysis, the RB LED had high economic efficiency. In conclusion, these results suggest that using RB LED for supplemental light source during low radiation in pepper greenhouse increase the yield and economic feasibility.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.569-572
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• 2012

식물공장의 다양한 건물형태에 따른 냉난방부하의 차이를 DesignBuilder를 이용하여 해석하였다. 엽채류 중 상추의 생육 적정온도인 $20^{\circ}C$를 실내온도로 설정하고 식물공장 외벽에 단일창호를 적용하여 온실형태에 따른 냉난방부하 변화를 계산하였다. 보광이 없는 건물자체의 냉난방부하를 계산한 결과 KNU 식물공장 단위유닛과 반원 온실형 식물공장이 냉방부하가 가장 적었다. 보광 적용 후에는 전반적으로 KNU 식물공장 단위유닛과 직사각형 식물공장이 양호한 냉난방 성능을 보여주었다. KNU 식물공장 창호의 면적이 와이드 스팬형보다 크기 때문에 건설비용의 증가가 예상되지만 회전형 스마트 조명 제어시스템을 적용하게 되면 재배면적을 넓히고 공간활용에 유리하다. 또한 LED 사용량을 줄일 수 있어 냉방부하와 보광에 드는 비용을 절감할 수 있다.