• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.7-12
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• 2017

This experiment was conducted to analyze the effect of drainage reuse rate on the growth and fruiting of summer paprika in closed hydroponic cultivation. The experiment was carried out for 25 weeks from March to September 2015 with 0, 20, 30, 50% mixing ratio of waste nutrient solution using non - recycling hydroponic cultivation as a control. As a result, stem diameter of the test was different in the groups 1 and 2, but no difference showed as the group progressed more than 3 groups. L.A.I tended to decrease with increasing drainage mixing ratio. The number of nodes in the 50% reuse test group was 1.4 compared to the control group, but there was no significant difference. The number of harvested nodes was significantly different in the control group (11.1 nodes) and the 50% reuse test group (8.7 nodes), and the harvested nodes tended to decrease as the drainage was reused. The ratio of harvest was also the same as that of the harvesting node, and the control was the highest at 33.2% and the lowest at the 50% reuse test at 27.6%. Relative yields were reduced by 30%, 35% and 45% in the control group in the first group, and this tendency was also observed in the second and fourth groups. However, in the 3 and 5 groups, the production of 50% test group increased by 13% and 5%. The ratio of unmarketable fruit was increased 2%, 4%, 4%, and 7% in 0%, 20%, 30% and 50% reuse test, respectively. In conclusion, if the decrease in yield due to the decline in early growth is carefully managed, even if the imbalance of inorganic ions occurs after the mid-term growth, the growth of the crop will enter into a stable period and the re-use will not be worried about the growth and the yield decrease.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.31-38
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• 2019

In this study, amine derivatives and ion exchange resins were selected to actively control penetration ions ($SO{_4}^{2-}$, $Cl^-$) as the element technology of repair materials for concrete structures in drainage environments. Ions ($SO{_4}^{2-}$, $Cl^-$) adsorption performance and corrosion resistance of calcium hydroxide solution with amine derivative and ion exchange resin were confirmed by ion chromatography and potentiostat analysis. As a result of the experiment, it was confirmed that the amine derivative is excellent in the adsorption of chlorine ion and the ion exchange resin is excellent in the adsorption of sulfate ion. It has been confirmed that corrosion resistance can be increased by proper combination of two materials in the calcium hydroxide solution containing sulfate ion and chloride ion simulating sewage environment.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.15-24
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• 2014

This study was performed to investigate the removal characteristics of heavy metals in Acid Mine Drainage (AMD) using pellet-type Zeolite-StarFish ceramics (ZSF ceramics), in which natural zeolite and starfish were mixed and calcined with wood flour. Kinetic experiment showed the removal reaction of heavy metals by ZSF ceramics reached the equilibrium status within 3 hours. The optimal calcination temperature range for removal of heavy metals was measured to be $800{\sim}1,000^{\circ}C$. The calcination time had little effect on the removal of heavy metal in AMD. The adequate dose of ceramics was shown to be 1.0~1.2 % for removal of heavy metals in AMD. High removal efficiencies of heavy metals (Al, As, Cd, Cu, Fe, Mn, Zn) in AMD, more than 95 % except for Pb, were obtained under the condition of dose of ceramics more than 1.0 %. The removal efficiencies of heavy metals increased with increasing mixing concentration of wood flour. The adequate mixing concentration of wood flour was observed to be 10 %. The batch experimental results exhibited that the ZSF ceramics could act as an efficient ceramics for removal of heavy metals in AMD and the wood flour could provide porous ZSF ceramics with enhanced removal efficiency of heavy metals.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.31-41
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• 1986

Knowledge of the degree of yield reduction due to water stress at different crop growth stages in rice production is important for rational scheduling of irrigation during periods of insufficient water supply. Previous studies to determine the degree of yield reduction duo to water stress suffered from interruptions by rain during experiment. Also the findings did rot relate the degree of water stress to the soil water potential and water deficit status of rice plants. In this study, two years experiments were conducted using the high yielding rice varieties, an Indica x Japonica (Nampoong) and a Japonica variety(Choochung). These were grown in 1/200$^{\circ}$ plastic pots placed under a rainfall autosensing, sliding clear plastic roof facility to control rainfall interruptions. The results obtained were as follows. 1.The two varieties differed in the growth stage most sensitive to water stress as well as the degree of yield reductions. When rice plants were stressed to the leaf rolling score 4 and soil water potential of about - 20 bar at major crop growth stages which included heading, booting, non-effective tillering, panicle initiation and early tillering stages, the yield reductions in the Indica x Japonica variety were 58%, 34%, 27%, 22%, and 21%, respectively, whereas in the Japonica vairety they were 23%, 36%, 1%, 13% and 22%, respectively. This result show that the recommended drainage during non-effective tillering is valid only for the Japonica variety. Sufficient irrigation at booting, heading and early tillering stages are necessary for both varieties. 2.The two varieties showed visible wilting symptoms when the soil water potential dropped to about - 3.0 bar. The Japonica variety showed more leaf rolling than the Indica X Japonica. However, it had a higher retention of leaf water content and greater stomatal diffusive resistance. When the soil water potential dropped, the Japonica variety showed leaf rolling score (LRS) 1 at 0 soil-5. 0 bar and LRS 2 at 0 soil -6.0 bar while the Indica X Japonica showed LRS 1 at 0 soil - 5.5 bar and LRS 2at 0 Soil - 9.0 bar. The stomatal diffusive resistance was maximum at the second top leaf blade in both varieties at intermediate water stress of 0 soil - 4.5 bar. 3.The number of days that was required for the soil water potential to drop to-3. 0 bar and to - 20.0 bar after drainage of irrigation water from the 20cm deep silty clay loam soil in the pots were 6 and 13 days, respectively for booting stage, and 7 and 11 days, respectively for heading stage, 9 and 12 days, respectively for panicle initiation stage, and 12 and 19 days, respectively for early tillering stage. 4.Water stress during the early tillering stage recorded the longest delay in beading time, the largest reduction in panicle numbers and a substantial yield decrease of 20%. This calls for better water management to ensure the availability of water at this stage, particularly during drought periods. In addition, a reexamination of the conventional inter-drainage practice during the non-effective tillering stage is necessary for the high yielding Indica X Japonica varieties.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.303-312
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• 2020

An underground deep tunnel system is a facility in form of a reverse siphon for an under flood defense structure. In this study, the 'Shinwol rainwater storage and drainage system', which is under construction for the first time in South Korea, in order to confirm the effects of undular bore and pressurized air on the hydraulic stability of the facility in various flood scenarios a hydraulic model experiment was performed. As a result of this study, it was analyzed that the undular bore generated downstream pushed the pressurized air collected in the facility while moving upstream, and the pressure inside the pipe increased at this time. It was analyzed that the pressure during the passage of the undular bore was greater than the sum of the static pressure and dynamic pressure at the time and overflow occurred when the cross-sectional size of the pressurized air was more than 40% of the cross sectional area of the tunnel. It is determined that this is correlated with the volume of pressurized air collected in the facility, and it is determined that it is necessary to study the relationship between velocity of undular bore and the volume of pressurized air in the future.

• Journal of Korea Water Resources Association
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• v.50 no.2
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• pp.129-138
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• 2017

In this study, the hydraulic model test was performed for the 3 vertical inlets of the Shinwol rainwater storage & drainage system that Seoul City plans to install, and the control discharge value actually measured was analyzed comparing to the value obtained using the theoretical control discharge equation suggested by Yu and Lee (2009). In the results, it was 66~69% compared to the value obtained from theoretical equation showing that the control discharge value according to the theoretical equation is calculated excessively. The sensitivity analysis by design factor was performed using 3 models conducted in this study and 15 hydraulic experiment models conducted in existing research Yu and Lee (2009). The sensitivity analysis of control discharge equation was performed by dividing $Q_{cm}/Q_{cp}$ into 3 ranges. The suggested equation considered only the influence on the tangential intake structure design factor B, z, ${\beta}$, e/B, so ${\theta}$, L considered complex influence suggested equation needed to be more improved.

• Horticultural Science & Technology
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• v.29 no.1
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• pp.23-28
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• 2011

Experiments were conducted to investigate the optimum concentration of the nutrient solution in strawberry 'Sulhyang' with hydroponics in relationship between root activity and nutrient concentrations. Nutrient solutions for strawberry, made by Yamazaki, were supplied EC 0.5, 1.0, 2.0 $dS{\cdot}m^{-1}$ during experiment period. Growth of shoot and root of strawberries grown in visible plastic pot was observed during experiment. Petiole length was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 2.0 and 0.5 $dS{\cdot}m^{-1}$. Leaf width was longest in plants grown in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Fruit length, fruit diameter, fruit weight and yield were higher in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ than 2.0 $dS{\cdot}m^{-1}$ treatment but, soluble solids of the fruit did not show statistical differences among treatments. Shoot dry weight was heaviest in EC 1.0 $dS{\cdot}m^{-1}$, followed by 0.5 and 2.0 $dS{\cdot}m^{-1}$. Root dry weight was heavier in EC 0.5 and 1.0 $dS{\cdot}m^{-1}$ but significantly light in 2.0 $dS{\cdot}m^{-1}$. pH of the drainage solution was elevated in low nutrient concentration and lowered in high concentration. Also root activity was high in low nutrient concentration and low in high concentration. As a result, the optimum EC for strawberry 'Sulhyang' was EC 1.0 $dS{\cdot}m^{-1}$ in this experiment. It was confirmed that there was high relationship between root activity and pH of drainage solution. This result will be utilized as an indicator for strawberry hydroponics.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.4
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• pp.301-306
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• 2008

This experiment was conducted to compare the agronomic characteristics, productivity of silage com and barley cropping, forage sorghum and barley cropping in accordance with Drainage Culvert Spacing at poorly drained paddy field in National Institute of Animal Science, at Seonghwan in Korea, March 2006 to May 2007. The emergency and flowering date were no different among treatments. Emergency rate and flowering date were 90% and July 26 in silage com, 91% and July 21 in forage sorghum, 92% and April 27 in barley, respectively. Dry matter yield was high in line with 3 m drainage culvert spacing (24,389 kg/ha) > 5 m (23,543 kg/ha) > 7 m (21,527 kg/ha) > 0 m (14,132 kg/ha). In cropping systems, dry matter yield of forage sorghum and barley (22,111 kg/ha) was higher than silage com and barley (19,684 kg/ha). Crude protein and TDN yield were high in line with 3 m (2,365 and 15,394 kg/ha) > 5 m (2,255 and 14,513 kg/ha) > 7 m (1,884 and 13,747 kg/ha) > 0 m (995 and 8,682 kg/ha). In cropping systems, crude protein and TDN (total digestible nutrients) yield of forage sorghum and barley cropping system (2,165 and 13,582 kg/ha) was higher than silage com and barley cropping system (1,576 kg/ha and 12,482 kg/ha), respectively. Consequently proper drainage culvert Spacing at poorly drained paddy field was 5 m with forage sorghum and barley cropping system.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.444-451
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• 2022

Recently, long-term cultivation is becoming more common with the increase in tomato hydroponics. In hydroponics, it is very important to supply an appropriate nutrient solution considering the nutrient and moisture requirements of crops, in terms of productivity, resource use, and environmental conservation. Since seasonal environmental changes appear severely in long-term cultivation, it is so critical to manage irrigation control considering these changes. Therefore, this study was carried out to investigate the effect of irrigation volume on growth and yield in tomato long-term cultivation using coir substrate. The irrigation volume was adjusted at 4 levels (high, medium high, medium low and low) by different irrigation frequency. Irrigation scheduling (frequency) was controlled based on solar radiation which measured by radiation sensor installed outside the greenhouse and performed whenever accumulated solar radiation energy reached set value. Set value of integrated solar radiation was changed by the growing season. The results revealed that the higher irrigation volume caused the higher drainage rate, which could prevent the EC of drainage from rising excessively. As the cultivation period elapsed, the EC of the drainage increased. And the lower irrigation volume supplied, the more the increase in EC of the drainage. Plant length was shorter in the low irrigation volume treatment compared to the other treatments. But irrigation volume did not affect the number of nodes and fruit clusters. The number of fruit settings was not significantly affected by the irrigation volume in general, but high irrigation volume significantly decreased fruit setting and yield of the 12-15th cluster developed during low temperature period. Blossom-end rot occurred early with a high incidence rate in the low irrigation volume treatment group. The highest weight fruits was obtained from the high irrigation treatment group, while the medium high treatment group had the highest total yield. As a result of the experiment, it could be confirmed the effect of irrigation amount on the nutrient and moisture stabilization in the root zone and yield, in addition to the importance of proper irrigation control when cultivating tomato plants hydroponically using coir substrate. Therefore, it is necessary to continue the research on this topic, as it is judged that the precise irrigation control algorithm based on root zone-information applied to the integrated environmental control system, will contribute to the improvement of crop productivity as well as the development of hydroponics control techniques.

• Korean journal of applied entomology
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• v.22 no.1 s.54
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• pp.1-6
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• 1983

The survey on the occurrence and distribution of barley stripe disease was conducted in the farmer's field of 19 gun (county) throughout Yeongmm area in May of 1982, in order to obtain a basic information on the breeding of resistant varieties, and for control of the disease. The percent of infected culms of barley stripe disease in Gyeongnam province (Southern Yeongnam) was higher $(13.7\%)$ them in Gyeong-bug $(6.9\%)$, northern Yeongnam, and especially, Ham-an, Milyang, Eui-chang and Weol-seong were severly occurred. The cultivar of Millyang 6 was slightly infected while the cultivars Olbori and Oweolbori were severely infected by the disease. Among soil conditions, the barley plant grown in the loam, clay and clay loam texture which have more availble moisture, and that of the plant cultivated in the poorly drained soils were shown to have severe infection. The barley plant grown in the soils in local valley $(18.8\%)$ where is frequently over saturated with water showed the more infection the barley plant grown in plains $(9.5\%)$. Generally, the poorer the soil drainage the more severeinfection occurred. Among cultivation conditions, the earlier the sowing dates of the barley, the less the percent of infected culms was observed. The heavier or lighter application of N fertilizer than the optimum to barley plant seemed to cause more infection.