• Horticultural Science & Technology
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• v.31 no.6
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• pp.726-731
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• 2013

Experiments were conducted to evaluate the effect of low temperature-darkness treatment on floral initiation in four kinds of Korean strawberry cultivars. Mother plants were planted on March 29 and daughter plants were raised for the experiment. Temperature treatment was done for 7, 14, and 21 days keeping $13^{\circ}C$ in cooling storage from August 29, September 5 and September 14 to September 21. After the treatment, flower bud initiation was examined by a microscope, and the seedlings were transplanted on hydroponic system with Yamazaki's strawberry solution of EC $0.8dS{\cdot}m^{-1}$ to check the flowering. 'Ssanta' and 'Maehyang' showed early flower bud initiation in 7 days treatment than 'Seolhyang' by microscope check. 'Ssanta', 'Daewang', and 'Maehyang' showed early flower bud initiation in 14 days treatment than 'Seolhyang'. There were no differences among the treatments in 21 days treatment. Percentage of flowering of 'Seolhyang' and 'Maehyang' by low temperature-darkness treatment didn't show any difference but 'Daewang' and 'Ssanta' showed high percentage of flowering. It suggested that low temperature-darkness treatment technique can be use for improving early flowering and yield of 'Ssanta' and 'Daewang' cultivars.

• Journal of Biosystems Engineering
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• v.15 no.4
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• pp.328-338
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• 1990

The objective of this study was to develop automatic systems of nutrient solution management for optimal nutrient solution environment and labor saving in water culture which enables factory crop production. In this study, an automatic control system and its driving program are developed to prepare, supply, and recover nutrient solution and to keep the optimal solution concentration level using microcomputers. Based on this study, the following conclusions are obtained: 1. The concentration measured by the system using oscillating circuit designed and built in this study, gave good agreements with the actual nutrient solution. 2. In water culture, the period of 12 hours for measuring concentration, pH, and temperature of the nutrient solution was optimum. Addition of control solution due to the decrease of the nutrient solution concentration is required in every 3 to 5 days. 3. It is estimated that the period of the whole solution change is 15 days, however, further research is needed to assure it. In addition, this period must be shortened in the future. 4. Both the hardware and software of the developed optimal nutrient solution control system in the water culture are working very well, however, it is necessary to develop a more economical one-chip micro controller to substitute for the microcomputer.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.153-160
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• 2015

The objectives of this study were to determine optimal length of off-time between irrigation cycles to improve irrigation efficiency using a frequency domain reflectometry (FDR) sensor-automated irrigation (FAI) system for tomato (Solanum lycopersicum L.) cultivation aimed at minimizing effluent from coir substrate hydroponics. For treatments, the 5-minute off-time length between 3-minute run-times (defined as 3R5F), 10-minute off-time length between 3-minute run-times (defined as 3R10F), or 15-minute off-time length between 5-minute run-times (defined as 5R15F) were set. During the 3-minute or 5-minute run-time, a 60mL or 80mL of nutrient solution was irrigated to each plant, respectively. Until 62 days after transplant (DAT) during the autumn to winter cultivation, daily irrigation volume was in the order of 3R5F (858mL) > 5R15F (409mL) > 3R10F (306mL) treatment, and daily drainage ratio was in the order of 3R5F (44%) > 5R15F (23%) > 3R10F (14%). Between 63 and 102 DAT, daily irrigated volume was in the order of 5R15F (888mL) > 3R5F (695mL) > 3R10F (524mL) with the highest drainage ratio, 19% (${\pm}2.6$), at the 5R15F treatment. During the spring to summer cultivation, daily irrigation volume and drainage ratio per plant was higher in the 3R5F treatment than that of the 3R10F treatment. For both cultivations, a higher water use efficiency (WUE) was observed under the 3R10F treatment. Integrated all the data suggest that the optimal off-time length is 10 minutes.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.248-255
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• 2013

This study examined an automated irrigation technique by a frequency domain reflectometry (FDR) sensor for scheduling irrigation for tomato (Solanum lycopersicum L. 'Starbuck F1') cultivation aimed at avoiding effluent from an open hydroponic system with coir substrate containing different ratios of chip-to-dust (v/v) content. Specifically, the objectives were to undertake preliminary measurements of irrigation volumes, leachate volume, volumetric water content and electrical conductivity (EC) in the substrate, plant growth, fruit yield, and water use efficiency resulting from variation in chip content as an initial experiment. Commercial coir substrates containing different percentages of chips and dust (0 and 100%, 30 and 70%, 50 and 50%, or 70 and 30%), two-story coir substrates with different percentages of chips in the lower layer and dust in the upper layer (15 and 85%, 25 and 75%, or 35 and 65%), or rockwool slabs were used. The results showed that a negligible or no leachate was found for all treatments when plants were grown under a technique for scheduling non-drainage irrigation using a frequency domain reflectometry (FDR) sensor. Daily irrigation volume was affected by chip content in both commercial and two-story slabs. The highest plant growth, marketable fruit weight, and water-use efficiency were observed in the plants grown in the commercial coir slab containing 0% chips and 100% dust, indicating that the FDR sensor-auto-mated irrigation may be more useful for tomato cultivation in coir substrate containing 0% chips and 100% dust using water efficiently and minimizing or avoiding leachate and thus increasing yield and reducing pollution. Detailed experiment is necessary to closely focus on determining appropriate irrigation volume at each of irrigation as well as duration of each individual irrigation cycle depending on different physical properties of substrates using an automated irrigation system operated by the FDR sensor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.780-790
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• 2015

Studies for a plants factory is progressing for cultivating various plants by the needs of the times and industry around world. However most studies is carried out only in lab sized plants factory. It does not consider an economic feasibility. The study for a large scale plants factory is very required to get an economic gain. In this paper we has been studying a smart farm factory based on ICT using the hydroponics ginseng. The smart farm factory is to extend a concept of the general plants factory to full automated factory. The factory can collect the information about growing of plants and automate operating and management of factory like the existing plants factory. Also it is the total plants factory management system, which analyzes the collected information for optimized growth and development of plants and applies the result to the system back.

• Journal of Bio-Environment Control
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• v.33 no.2
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• pp.114-119
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• 2024

Rockwool substrate has superior physicochemical characteristics and is often used in crop cultivation. However, rockwool substrate has the disadvantages of high purchase cost and difficulty in disposal. Reuse of substrate can compensate for these disadvantages. Substrate must be disinfected and rehydrated during reuse, and various physicochemical changes during this process must also be considered. This study was to compare the physical properties of two types of rockwool substrates (reused and unused) and to evaluate the reuse potential of rockwool substrate by analyzing the chemical properties of the reused rockwool substrate during the rehydration process. The experiment on substrate physicochemical properties comparison was conducted from March to August 2023 using used rockwool substrates in tomato cultivation and unused rockwool substrates. Drainage time, drainage volume, and substrate weight were measured using load cells installed at the top and bottom of the irrigation monitoring system. The reused rockwool substrate weight and density were higher than those of the unused rockwool substrate, while the average drainage time after irrigation was 1.5 times longer for the reused rockwool than for the unused rockwool. The salinity concentration in different parts of the reused rockwool substrate was found to be lower in the reused rockwool substrate compared to the unused rockwool substrate. The electrical conductivity of the drainage was at its peak at the beginning of the drainage and decreased exponentially as the drainage volume increased. Change in electrical conductivity of the drainage over the irrigation time showed an exponential decay pattern. Through the experiments, the potential reusability of the rock wool substrate was assessed by conducting a comparative analysis of its physicochemical properties.

• Korean Journal of Environmental Agriculture
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• v.37 no.4
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• pp.251-259
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• 2018

BACKGROUND: Various culture media have been used for hydroponic cultures of horticultural plants under the smart greenhouses with natural and artificial light types. Management of the culture medium for the control of medium amounts and/or necessary components absorbed by plants during the cultivation period is performed with ICT (Information and Communication Technology) and/or IoT (Internet of Things) in a smart farm system. This study was conducted to develop the cloud-based data analysis system for effective management of culture medium applying to hydroponic culture and plant growth in smart greenhouses. METHODS AND RESULTS: Conventional inorganic Yamazaki and organic media derived from agricultural byproducts such as a immature fruit, leaf, or stem were used for hydroponic culture media. Component changes of the solutions according to the growth stage were monitored and plant growth was observed. Red and green lettuce seedlings (Lactuca sativa L.) which developed 2~3 true leaves were considered as plant materials. The seedlings were hydroponically grown in the smart greenhouse with fluorescent and light-emitting diodes (LEDs) lights of $150{\mu}mol/m^2/s$ light intensity for 35 days. Growth data of the seedlings were classified and stored to develop the relational database in the virtual machine which was generated from an open stack cloud system on the base of growth parameter. Relation of the plant growth and nutrient absorption pattern of 9 inorganic components inside the media during the cultivation period was investigated. The stored data associated with component changes and growth parameters were visualized on the web through the web framework and Node JS. CONCLUSION: Time-series changes of inorganic components in the culture media were observed. The increases of the unfolded leaves or fresh weight of the seedlings were mainly dependent on the macroelements such as a $NO_3-N$, and affected by the different inorganic and organic media. Though the data analysis system was developed, actual measurement data were offered by using the user smart device, and analysis and comparison of the data were visualized graphically in time series based on the cloud database. Agricultural management in data visualization and/or plant growth can be implemented by the data analysis system under whole agricultural sites regardless of various culture environmental changes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.379-386
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• 2021

This study was undertaken to develop a cascade-type continuous culture system (CCCS) that combines both ICT and biotechnology (BT), for the mass production of microalgae. This system is capable of maintaining the essential culture conditions of pH, temperature, carbon dioxide, and illuminance control, which are key parameters for the growth of microalgae, and is economical for producing microalgae regardless of the season or location. It has the added advantage of providing stable and high productivity. In the current study, this system was applied to culture microalgae for 71 days, with subsequent analysis of the experimental data. The initial O.D. of the culture measured from incubator 1 was 0.006. On the 71st day of culture, the O.D.s obtained were 0.399 (incubator 1), 0.961 (incubator 2), 0.795 (incubator 3), and 0.438 (incubator 4), thereby confirming the establishment of continuous culture. Thus, we present a smart-farm based on ISMC (in-situ monitoring and control) for a mass culture method. We believe that this developed technology is suitable for commercialization, and has the potential to be applied to hydroponics-based cultivation of microalgae and cultivation of high-value-added medicinal plants as well as other plants used in functional foods, cosmetics, and medical materials.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.266-270
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• 2004

A rose factory type is a system that enables year-round, planned and mass production of high quality cut-rose. Conversion of a conventional system to a rose factory is essential to increase cut-rose export. Controlling root Bone in culled rose production factory is very important for economic and efficient production of rose. This study was conducted to determine optimum root zone temperature of nutrient solution in single-stemmed rose production system. The optimum temperature of the nutrient solution for growth, photosynthetic and transpiration rates for 'Red Velvet' was $15\~20^{\circ}C$. Whereas the optimum temperature for 'Vital' was $10\~15^{\circ}C$. However, growth was almost sloped at $30^{\circ}C$, resulting in concluding the adaptation of 'Vital' to high temperature was poor as compared with 'Red Velvet'.

• Journal of Bio-Environment Control
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• v.15 no.1
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• pp.53-68
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• 2006

This experiment was conducted to investigate the effects of diurnal alternation of nutrient solution salinity on growth and fruit quality of tomatoes (Lycoperisicon esculentum cv. 'House momotaro') hydroponically grown in root intercept bag-NFT (RIB-NFT) system. Plant height was the lowest in the high concentration during daytime (6/1 $dS\;m^{-1}$, day/night). Yield was very high in the concentration of 1/1 $dS\;m^{-1}$, it decreased with increasing the concentration of nutrient Yield was higher at low concentration (4/1 $dS\;m^{-1}$) at nighttime compared to the same concentration (4/4 $dS m^{-1}$) at daytime and nighttime, and the reverse (1/4 $dS\;m^{-1}$) was similar to the control (perlite culture). Yield was greatly reduced by higher concentration at daytime than nighttime, and the decrease was alleviated by lower concentration at nighttime. With increasing the concentration of nutrient solution during daytime, sugar content of tomato fruit was increased, but yield was decreased. In the other experiment, tomato plants were hydropoically cultured in NFT system diurnally alternated between Aichi's solution and $Ca(NO_3)_2$ solution. $Ca(NO_3)_2$ solution was supplied for 4 hours from 10:00 to 14:00 at daytime and from 22:00 to 2:00 at nighttime, respectively, and Aichi's solution was supplied for the time except the 4 hours. Ca content of leaves and sugar content of fruit were increased by supplying $Ca(NO_3)_2$ solution at daytime compared to nighttime, but plant growth was greatly suppressed by supplying $Ca(NO_3)_2$ solution with the concentration of 4 $dS\;m^{-1}(4/4^{Ca}\;dS\;m^{-1})$ at nighttime.