• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2000.11a
• /
• pp.703-710
• /
• 2000

기존의 비상구 표시등은 20-30(W) 정도의 많은 전력 소모와 2천시간 정도의 짧은 램프 수명 등으로 인해 전기에너지의 소모가 많으며, 부피가 커 시공 및 설치가 어렵다. 따라서, 본 논문에서는 도광판을 사용한 비상등의 개발에 관하여 연구하기 위하여 가시광선 투과율이 94%이상으로 높고 가공이 용이한 투명 PMMA(Poly Methyl Meth Acrylate)판에 광반사면을 광학적 시뮬레이션에 의해 설계된 V자형 홈선을 가공하여 비상등의 도광판으로 사용한다. 이 구조는 기존의 비상등에 비해 광이용 효율이 높고, 설계의 자유도가 높아질 것으로 기대된다. 또한, CCFT(Cold Cathode Fluorecent Tube) 램프, 광확산필름, 프리즘필름, 몰드프레임 등을 이용하여 광이용 효율을 극대화하는 구조를 고안하고, 인버터 구동을 위한 주변회로 시스템을 개발하여 초절전형 평판 비상등 시스템의 양산 기술을 확보함을 목적으로 한다. 이로부터 휘도 2000cd/$m^2$, 휘도균일도 90%이상의 특성과 기존의 비상등 대비 전기 에너지 50%이상이 절감 가능한 비상등이 개발될 수 있다.

• Horticultural Science & Technology
• /
• v.34 no.1
• /
• pp.84-93
• /
• 2016

Plant factories with artificial lights require a large amount of electrical energy for lighting; therefore, enhancement of light use efficiency will decrease the cost of plant production. The objective of this study was to enhance the light use efficiency by using filters to diffuse the light from LED sources in plant factory conditions. The two treatments used diffuse glasses with haze factors of 40% and 80%, and a control without the filter. For each treatment, canopy light distribution was evaluated by a 3-D ray tracing method and canopy photosynthesis was measured with a sealed acrylic chamber. Sixteen lettuces for each treatment were cultivated hydroponically in a plant factory for 28 days after transplanting and their growth was compared. Simulation results showed that the light absorption was concentrated on the upper part of the lettuce canopy in treatments and control. The control showed particularly poor canopy light distribution with hotspots of light intensity; thus the light use efficiency decreased compared to the treatments. Total light absorption was the highest in the control; however, the amount of effective light absorption was higher in treatments than the control, and was highest in treatment using filters with a haze factor of 80%. Canopy photosynthesis and plant growth were significantly higher in all the treatments. In conclusion, application of the diffuse glass filters enhanced the canopy light distribution, photosynthesis, and growth of the plants under LED lighting, resulting in enhanced the light use efficiency in plant factory conditions.

• Proceedings of the Korean Society for Bio-Environment Control Conference
• /
• 1994.05a
• /
• pp.108-110
• /
• 1994

시설에서 오이를 재배할 때 육묘방법과 정식조건 그리고 유인방법에 따라 재배환경에 대한 적응력이 다르기 때문에 그 때마다 생육, 수량 및 품질에 미치는 영향이 크다. 특히 이러한 재배환경 등은 오이의 조기안전다수확과 고품질을 꾀하기 위해서는 많은 연구가 요구되고 있는 것이 현실이다. 따라서 본 실험은 오이의 주지를 어떻게 유인하느냐에 따라 나타나는 광이용효율 등이 수량과 품질에 미치는 영향을 검토하고자 수행되었다. (중략)

• Horticultural Science & Technology
• /
• v.31 no.5
• /
• pp.565-572
• /
• 2013

The objective of this study was to describe and analyze the effect of high pressure sodium lamp lighting (HPS) on dynamics of growth and dry matter partitioning, and light use efficiency of sweet pepper crop grown over winter season. Young sweet pepper seedlings were planted at 3.75 plants per $m^2$ on September 29, 2010 and treated with HPS for 16 hours from December 14, 2010 until March 18, 2011. The number of leaves per plant were significantly increased with HPS, whereas the number of internodes and leaf area were less affected. HPS reduced the plant height with higher number of fruits per stem compared to those of without HPS lighting (CON). There were large differences in total dry mass production, stem and fruit dry mass between HPS and CON and those with HPS increased by 67.8%, 28.5%, and 97.1% compared to CON, respectively. Each organs of dry mass partitioning was calculated by leaf, stem or fruit growth rate divided by total plant growth rate. Dynamics of dry mass partitioning to leaf and stem between HPC and CON was measured in range of 45-47% at beginning of growth phase and drastically decreased after starting fruit growth in both treatments. Dry matter partitioning to vegetative organs was 4% higher compared to the plant grown under HPS lighting. Averaged dry matter partitioning to fruit with HPS, however, was largely increased by 14.2% compared to CON. Dynamics of the plant growth were well described by expolinear growth equation with three parameters of maximum relative growth rate, absolute growth rate and lost time to reach linear phase. The maximum growth rate of leaf, stem and fruit with HPS was increased by 18.6%, 74.7%, and 143.5% compared to CON. There was a linear relationship between intercepted light integral and vegetative organs (leaf and stem), fruit or total dry mass production. Light use efficiency (LUE, $g{\cdot}MJ^{-1}$) of total dry mass was $4.90g{\cdot}MJ^{-1}$ for HPS and $3.84g{\cdot}MJ^{-1}$ for CON, LUE of vegetative organs was $1.56g{\cdot}MJ^{-1}$ for HPS and $1.61g{\cdot}MJ^{-1}$ for CON and LUE of fruit dry mass was $3.34g{\cdot}MJ^{-1}$ for HPS and $2.23g{\cdot}MJ^{-1}$ for CON. The difference in LUE of total dry mass between treatments, therefore, occurred mainly from the different in LUE of fruit dry mass.

• Korean Journal of Environmental Biology
• /
• v.34 no.4
• /
• pp.264-271
• /
• 2016

The objective of this study was to determine the growth and light utilization efficiency of garden plants in shade area through chlorophyll fluorescence reaction analysis. Ten garden plants was grown for 75 days under 50% and 80% shading conditions. Under shading, $ET2_O/RC$, the fluorescence parameter related to electron-transport in photosystem II, was effectively enhanced. However, the electron transport flux until PSI acceptors per reaction center ($RE1_O/RC$) was reduced. These changes in photochemical parameters evoked a decrease in performance index (PI) and driving force (DF) of electron transport flux. In addition, some photochemical parameters such as $F_V$, $FV/F_O$, $RE1_O/RC$, $ET2_O/RC$, $PI_{TOTAL\;ABS}$, and $DF_{TOTAL\;ABS}$ were found to be important for shade tolerance. Three species (Pachysandra terminalis Siebold & Zucc, Physostegia virginiana L., and Carex maculata Bott) were found to be shade tolerant. Based on these results, shading factor index (SFI) deduced from photochemical parameters is useful for evaluating of shading stress of garden plants.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.21 no.4
• /
• pp.261-268
• /
• 2019

Climate change and drought stress are having profound impacts on crop growth and development by altering crop physiological processes including photosynthetic activity. But finding a rapid, efficient, and non-destructive method for estimating environmental stress responses in the leaf and canopy is still a difficult issue for remote sensing research. We compared the relationships between photochemical reflectance index(PRI) and various optical and experimental indices on soybean drought stress under climate change conditions. Canopy photosynthesis trait, biomass change, chlorophyll fluorescence(Fv/Fm), stomatal conductance showed significant correlations with midday PRI value across the drought stress period under various climate conditions. In high temperature treatment, PRI were more sensitive to enhanced drought stress, demonstrating the negative effect of the high temperature on the drought stress. But high CO₂ concentration alleviated the midday depression of both photosynthesis and PRI. Although air temperature and CO₂ concentration could affect PRI interpretation and assessment of canopy radiation use efficiency(RUE), PRI was significantly correlated with canopy RUE both under climate change and drought stress conditions, indicating the applicability of PRI for tracking the drought stress responses in soybean. However, it is necessary to develop an integrated model for stress diagnosis using PRI at canopy level by minimizing the influence of physical and physiological factors on PRI and incorporating the effects of other vegetation indices.

• Journal of Bio-Environment Control
• /
• v.31 no.3
• /
• pp.180-187
• /
• 2022

In order to select suitable light in a plant factory, electric energy use efficiency and light use efficiency should be considered simultaneously to consider operating costs as well as quantitative and functional aspects. The growth characteristics, electric energy use efficiency, light use efficiency by light intensity, LED ratio, and photoperiod conditions were compared together. Light intensity is 60, 130, 230, and 320 µmol·m^-2·s^-1 treatments, and light quality is the mixing ratio of red light and blue light 8:2, 6:4, 4:6, and 2:8 treatments. Photoperiod is 9, 12, 15, and 18 hours treatments based on the daytime. In the light intensity experiment, the growth rate increased as the light intensity increased, but there was no significant difference in the light use efficiency. When comparing the leaf fresh weight per power consumption, only the 320 µmol·m^-2·s^-1 treatment group showed significantly low efficiency, and there was no significant difference in the other treatments, so 230 µmol·m^-2·s^-1, which produced the most, was the most efficient. In the light quality experiment, the ratio of red light and blue light was measured to be high at the same time as the growth rate and light use efficiency in RB 8:2, and there was no significant difference in color difference and flavonoids content, so a Red:Blue ratio of 8:2 was the most suitable condition. In the photoperiod experiment, the longer the photoperiod, the higher the growth rate. However, there was no significant difference in the growth rate over 12 hours of daytime, so 12 hours considering the light consumption efficiency was a suitable condition. Based on the above results, LED light environmental conditions for perilla growth in plant factories were light intensity, light quality, and day length of 230 µmol·m^-2·s^-1 or more, 8:2, and 12 hours or more, respectively.

• Korean Journal of Remote Sensing
• /
• v.34 no.6_1
• /
• pp.1055-1066
• /
• 2018

Vegetation indices on the basis of optical characteristics of vegetation can represent various conditions such as canopy biomass and physiological activity. Those have been mostly developed with the large-scaled applications of multi-band optical sensors on-board satellites. However, the sensitivity of vegetation indices for detecting vegetation features will be different depending on the spatial scales. Therefore, in this study, the investigation of photochemical reflectance index (PRI), known as one of useful vegetation indices for detecting photosynthetic ability and vegetation stress, under the three spatial scales was conducted using multi-spectral camera installed in unmanned aerial vehicle (UAV),field spectrometer, and leaf reflectometer. In the leaf scale, diurnal PRI had minimum values at different local-time according to the compass direction of leaf face. It meant that each leaf in some moment had the different degree of light use efficiency (LUE). In early growth stage of crop, $PRI_{leaf}$ was higher than $PRI_{stands}$ and $PRI_{canopy}$ because the leaf scale is completely not governed by the vegetation cover fraction.In the stands and canopy scales, PRI showed a large spatial variability unlike normalized difference vegetation index (NDVI). However, the bias for the relationship between $PRI_{stands}$ and $PRI_{canopy}$ is lower than that in $NDVI_{stands}$ and $NDVI_{canopy}$. Our results will help to understand and utilize PRIs observed at different spatial scales.

• Korean Journal of Environmental Biology
• /
• v.41 no.3
• /
• pp.283-290
• /
• 2023

The Republic of Korea reclaimed land to increase its food self-sufficiency rate, but the yield was reduced due to abnormal climate. In this study, it was hypothesized that rapid and continuous monitoring technology could help improve yield. Using the vegetation index (VI) analysis, the drought stress index was calculated and the drought stress for corn grown in Hwaong, Saemangeum, and Yeongsan River reclaimed tidal land was predicted according to drying treatment. The vegetation index of corn did not decrease during the last 20 days of irrigation when soil moisture rapidly decreased, but decreased rapidly during the 20 days after irrigation. The reduction rate of the vegetation index according to the drying treatment was in the order of Saemangeum>Yeongsan River>Hwaong reclaimed tidal land, and normalized difference vegetation index(NDVI) decreased by approximately 50% in all reclaimed tidal lands, confirming that drought stress occurred due to the decrease in moisture content of the leaves. In addition, structure pigment chlorophyll index (SIPI) and photochemical reflectance index (PRI), which are calculated based on changes in light use efficiency and carotenoids, were reduced; drought stress caused a decrease in light use efficiency and an increase in carotenoid content. Therefore, vegetation index analysis was confirmed to be effective in evaluating and predicting drought stress in corn growing on reclaimed tidal land corn.

• Korean Journal of Environmental Biology
• /
• v.34 no.3
• /
• pp.161-168
• /
• 2016

In this study, growth enhancing effect of hatchery waste egg decomposed liquid fertilizer in pepper plant cultivation through chlorophyll fluorescence (O-J-I-P) analysis. In a whole growth period, egg decomposed fertilizer treated pepper grew well than non treated plant, though it was not statistically significantly different. Amount of chlorophyll fluorescence of non treated plant was higher thant that of fertilizer treated plant. It is determined that eventually lead to increased photosynthesis. In this study, six parameters, Fo, ABS/RC, RC/ABS, TRo/RC, DI0/RC, and DF Total ABS were the important factors represent efficiency of photochemical responses of pepper plant treated with hatchery waste egg decomposed fertilizer.