• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.210-214
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• 1996

The measuring system was developed for automation of hydroponic culture. It runs in Windows 3.1 and 95. Main window contains greenhouse screen and menu bars such as system setting, sensor calibration, greenhouse status, actuator control, file management, view, and help. Users can use pop-up menu, tool bar and status bat as well as menu bar for manipulation. Especially it was designed to retain flexibility for researchers, who changed detecting sensors frequently. Users can change storage intervals of files, of which 3 types were prepared to use in other software like as statistical programs, graphic programs and/or spread sheets. This system was adopted to deep flow culture system and evaluated to be appropriate for any kind of hydroponic systems.

• The Plant Pathology Journal
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• v.20 no.4
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• pp.277-282
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• 2004

Amendments of a recirculating nutrient solution with potassium silicate were evaluated as a means to control Phytophthora capsici infections on pepper plant(Capsicum annuum L.). Supplying the solutions with 100 or 200 ppm of silicate significantly reduced motility, root decay, and yield losses attributed to infection of P. capsici. Treating inoculated plants with potassium silicate increased root dry weights and number of fruit, especially high-grade fruit. Results were slightly superior to non-inoculated controls. The two varieties, PBC 137 and PBC 602, responded similarly to the treatments. No significant differences were observed between the 100- and 200 ppm silicate treatments. Results were better when greenhouse conditions favored the spread of P. capsici. Silicon alone did not increase pepper yield, suggesting that it acts as a disease suppression agent rather than as a fertilizer, The phenomena by which silicon confers protection against P. capsici infection and disease development are not fully understood, but our results indicate that mechanisms other than a mechanical barrier to fungal penetration are involved.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.584-590
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• 1993

The constructed closed recycling system discussed in this technical report will be economically viable in future for the production of fish and vegetable in earth, space station and space colony, further, it will contribute a lot in the prevention of pollution in the world's ecological system. To make combined system, water management (Nitrification) is required, and it took 45 days to breed microorganism which facilitates this process. After this period , the recycle was confirmed to be working .Using derived equations, the expected nutrient characteristics of waste water were determined and it was found that the resulting nutrient balance was almost same as that in hydroponic solution when KOH was added to maintain pH level. Reverse osmosis (RO) system could solve the problem of the low nutrient concentration . It was found that plants grow well in fish waste water which was produced using RO system. RO system could combine fish and plant production through the advantageous use of separated high concentration water for plant and permeated water for fish in integrated combined system.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.348-353
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• 2007

A solid state ion sensor module has been developed and evaluated for hydroponic nutrients analysis. The sensor module consisted of five ion-selective electrodes (ISE) fabricated by screen-printing technology. The electrochemical responses of ion sensors for nitrate, ammonium, potassium, calcium, and pH were measured with specially designed 7-channel low voltage signal transducers. The analytical characteristics of the sensors were comparable with those of conventional ISE sensors. The solid state ion sensors exhibit linear relationships over five concentration decades. Detection limit of the sensors were $5.6{\times}10^{-5}{\sim}1.6{\times}10^{-7}M$ depends on ions. Performance test results showed that relative errors of measured ion concentrations were less than 5% for $NO_3{^-},\;K^+,\;Ca^{2+}$ ion, and pH. The concentration of $NO_3{^-},\;NH_4{^+},\;K^+,\;Ca^{2+}$, and pH ion in standard solution and nutrient solutions could be determined by direct potentiometric measurements without any conditioning before measurements.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.412-416
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• 2006

A magnetic field oscillator was designed and made. The oscillator was installed around a water pipe and radiated into water which was provided for vegetables cultivation. The oscillator was made with a helmholtz coil and installed a magnetic field sensor inside. The class E amplifier circuit with frequency variance was also used. Hydroponic and soil cultural methods were used for cultivation of lettuce and chinese cabbage with magnetic field water and without. Vitamin C ingredients in the lettuce and chinese cabbage which were grown with magnetic field water were 2.8 times and 1.2 times higher than without the magnetic water. Moreover, the growth acceleration effect of vegetables was shown in lettuce cultivated with the magnetic field water.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.4
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• pp.345-350
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• 1997

Using modified Lincoln solution, hydroponic system was developed to compare simultaneously a range of pasture species in terms of relative growth rate(RGR), rate of roots to shoots, and relative root volume and root area. Modified Lincoln solution achieved optimum growth of nineteen forage species tested, and was proved to be a good method for studying plant root characteristics. RGR was measured sucesshlly showing reasonably consistant values over time. There was a much differences in rootkhoot ratio between species within groups as between groups. Root tissue density was lower in grasses than legume or herb group. Root area index was very high for grasses and herbs, and this index should be useful for evaluating the comparative root system of different species.

• Journal of Bio-Environment Control
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• v.1 no.2
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• pp.175-180
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• 1992

Cherry tomatoes(Lycopersicon esculentum) were grown in circulating deep flow hydroponic system. The pH of the nutrient solution was increased and the EC was decreased with time. The clusters of ‘Mini Carol’ were branched severely, whereas those of ‘Chelsea Mini’ and ‘Popo’ were a little branched or not. The vegetative growth was similar between cultivars. But the yield of fruits was by far the largest in ‘Mini Carol’ compared to other cultivars, and not different between ‘Chelsea Mini’ and ‘Popo’. Internal qualities of fruits, like as sugar, sugar/organic acid, and vitamin C, are good in ‘Mini Carol’. As the result of panel test, ‘Mini Carol’ is good for softness, easeness of eating, toughness of skin and so on, so it is believed that ‘Mini Carol’ is the most acceptable to consumers in hydroponic culture.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.53-57
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• 1993

This study was carried out to investigate the appropriate hydroponic system when cherry tomatoes were grown in summer. The base diameter of the trunk, leaf length, leaf width, and the length of cluster were good in deep flow culture(DFC), and not different between NFT and rockwool culture. The first time of flowering and the fruit coloring per cluster were not different among cultural systems, but the marketable yields were good in DFC. In DFC, ％ dry weight, firmness, the content of organic acid and sugar were low, and the ratio of sugar/organic acid and vitamin C were high. So DFC is recommended for the summer cultivation of cherry tomatoes.

• Elastomers and Composites
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• v.35 no.3
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• pp.227-235
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• 2000

This study focused on the recycling technology and application of waste polyurethane scrap($5{\sim}7mm$) and waste urethane form from the footware scrap. Firstly we suggest the waste polyurethane can be used as a component of medium for hydroponic rose culture. Secondly, recycled thermoplastic polyurethane(RTPU) was produced and blended it with high impact polystyrene(HIPS). And also, in order to extend application of recycling field, the former was produced with adding the amine foaming agent to RTPU/HIPS alloy. The main purpose of this study is to diverse of the recycling of the waste polyurethane.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.103-111
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• 2019

Gray mold caused by Botrytis cinerea on strawberry plants is an economically significant disease in Korea. The rates for diseased fruits are high during the strawberry harvesting period from December to February, especially in hydroponic cultivation. This study assessed the effect of the nitrogen type in the soil culture and the electrical conductivity (EC) of the nutrient solution in a hydroponic culture on the gray mold incidence in 'Seolhyang' strawberry plants. The nitrogen sources assayed included calcium nitrate tetrahydrate (CN4), calcium nitrate decahydrate (CN10), ammonium sulfate (AS), and commercial fertilizer 213 (213). The effect of the EC was tested at 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$. The occurrence of gray mold varied according to the nitrogen type. The disease incidence and nitrogen content for the main nitrogen type were higher compared to the non-treated control. The AS treatment showed the highest occurrence of tipburn and gray mold. The incidence of gray mold as well as the nitrogen and phosphorus content of the leaves increased as the EC level was increased. These results indicate that the incidence of gray mold in strawberry plants is related to the nitrogen content of the leaf and the EC of the nutrient solution.