• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.74-79
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• 2001

A one-dimensional flood routing model was formulated to simulate the flood flow of drainage sub-canal using the continuity equation of paddy field and the momentum and continuity equation of drainage sub-canal. The model was applied for evaluating the hydraulic characteristics of drainage sub-canal at large-sized paddy fields. The model applicability was evaluated with field data and the simulated results were in good agreement with the observed data.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.3
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• pp.3-14
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• 2004

A two-dimensional numerical model based on a finite volume method was formulated to solve the shallow water equations and applied for evaluating drainage characteristics at large-sized paddy fields. Manning roughness coefficient was calibrated using the observed inundating depths at drainage tests, and used for validating the model with the results from another drainage test. The simulated results were in good agreement with the observed inundating depths. The result of surface drainage showed that the longer width of the outlet was or the more the number of drainage outlet was, the shorter the drainage time was taken, and the larger the size of the field become, the longer the drainage time was taken, and the field shape had little effect on drainage time. To reduce the drainage time to 24 hours, the outlet is located lower than the elevation of the basin and small drainage ditch is constructed at the field. The results showed that the drainage time was taken short as the small drainage ditch was constructed. The comparison of drainage time as to the size of field constructed small drainage ditch showed the field, 100m ${\times}$ 200 m, can be drained in 24 hours.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.4
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• pp.3-11
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• 2004

A finite volume model is developed to simulate the surface irrigation at a paddy field. The model's capabilities are validated through comparison with the simulafed results and the observed data obtained by various experimental tests, and the simulated results are in good agreement with the observed pending depth. The result of surface irrigation simulation shows that the longer the paddy field's the length of long-sided becomes, the longer the advance and storage time is taken. To analyze surface irrigation performance with variable inflow rate, three patterns of flow variation-constant rate, initially high then low, and initially low then high-were studied. The results show that at the pattern with initially high followed by low during the latter half of the irrigation the advance time is shortest, but the pending depth of irrigation completion and irrigation effiency are the little difference between irrigation patterns.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.2
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• pp.1-9
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• 2014

A modeling system is constructed by integrating an one-dimensional unsteady flow simulation model and a hydrologic model to simulate flood flows in drainage channel networks of paddy field districts. The modeling system's applicability is validated by simulating flood discharges from a paddy field district, which consists of nine paddy fields and one drainage channel. The simulation results are in good agreement with the observed. Particularly, in the verification stage, the relative errors of peak flows and peak depths between the observed and simulated hydrographs range 8.96 to 10.26 % and -10.26 to 2.97 %, respectively. The modeling system's capability is compared with that of a water balance equation-based model; it is revealed that the modeling system's accuracy is superior to the other model. In addition, the simulations of flood discharges from large-sized paddy fields through drainage channels show that the flood discharge patterns are affected by drainage outlet management for paddy fields and physical characteristics of the drainage channels. Finally, it is concluded that to efficiently design drainage channel networks, it is necessary to analyze the results from simulating flood discharges of the drainage channel networks according to their physical characteristics and connectivities.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.343-356
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• 1996

The plot geometry of the paddy land is directly related to the performance of machines, especially those having a large size and high speed. The study was to investigate the optimum plot geometry from the standpoint of mechanization. A simulator, Field-Plot-Structure-Evaluation-System(FPSES) was developed for evaluation of the field performance of machines according to the plot geometry. The efficiency and capacity of different sizes of machinery used for rice farming functions were analyzed for a various combination of plot geometry, which could be used as reference for the land reclamation planning and mechanization programming. It is shown that the plot size of about two hectares having a length of 200m and width of loom may be optimum, considering the efficiency and capacity of large sized machinery available currently and in near future.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.2
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• pp.85-96
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• 2022

The study is aimed to investigate the features and socio-economic background of farmland consolidation project with medium-sized paddy plot at irrigation associations during the Japanese colonial period in Korea. Most of farmland consolidation works in the 1940s was composed of independent irrigation and drainage ditches along the short side of field plot. However, the number of farm roads at farmland consolidation zone was much smaller than number of irrigation ditches to decrease reduction in farmland area. The standard field plot was medium-sized (about 20-40 ares) in Korea but small-sized (about 10 ares) in Japan in this period. As the result of farmland consolidation works, the unit water requirement was increased to 0.0035 m³/s/ha, and the unit area drainage discharge was over 2.0 m³/s/km² in many cases. The farmland consolidation with medium-sized plot have been spread under the colonial landlord system, where major landlords occupied a large share of farmland and managed corporate farming to gain more benefit. The reasons for spread of farmland consolidation with medium-sized plot may be as follows: high net profit ratio, an increase in land price, and labor savings in rice farming. The farmland consolidation with medium-sized plot in the colonial period showed intermediate features between the farm consolidation with small-sized plot for an increase in land productivity in Japan and the farm consolidation with medium-sized plot for an increase in labor productivity after the 1960s.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.999-1008
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• 1996

The development and improvement of the originally designed direct rice sowing machine were carried out for the specific purpose of saving labor and increasing the efficiency of field operations in rice cultivation in the northern part of Japan. the prototype super wide spreader has a unique mechanism which propels rice seeds by compressed air and spreads them from the pivoting nozzle while the machine is in motion. The effective field capacity of sowing operation is about 6 ha/h. This spreader can also handle granular chemicals such as fertilizers, herbicides, pesticides and insecticides.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.2
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• pp.3758-3762
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• 1975

In order to find out the optimum size of nozzle of the power sprayer in the paddy field, four different sized hole of nozzles were tested on its discharge volume per unit time and its effective covering distance. 1. The discharge rate of each nozzle is proportional to square root of the transmitted internal pressure of liquid, and the discharge coefficient ranges from 0.82 to 0.86 at the pressure of 20 to 30 kg/$\textrm{cm}^2$. 2. The effective covering distance is increased as the size of the hole is larded and also the pressure is increased under under the limited pressure. Generally, the effective covering distance is not greatly increased at the pressure of above 25kg/$\textrm{cm}^2$. The distance from the nozzle to the spot where the largest amount of droplets are dropped is about 14.5m for 3.05mm nozzle and 16m for 4.05mm nozzle in the pressure range from 20 to 25kg/$\textrm{cm}^2$. 3. From the above results it is concluded that the 3mm nozzle with the power sprayers, which are now being supplied to the farmers, can be used for disease and insect control on the paddy field of which block size is 30m${\times}$100m, and operators need not to enter the field for spraying. For the 40m${\times}$100m block, 4mm nozzle should be used with large size of pump which discharge capacity is 60l/min or more.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.401-407
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• 2006

This study was conducted to investigate the effect of onion cultivation under paddy and upland condition on the yield and storage of onion bulbs. In comparison of soil conditions, nitrogen, phosphate, potassium content and average temperature in upland condition were higher than those of paddy condition, but calcium, magnesium, sodium and water content in paddy condition were higher than those of upland condition. The growth of aerial part was better in upland cultivated condition. It showed that bulb formation in paddy cultivated condition was faster during in early growth stage, but was slower during in late growth stage. Average bulb size and weight were higher in upland cultivated condition, but dry weight per 100 g fresh weight and bulb hardness were higher in paddy cultivated condition. Sugar contents, inorganic compounds, nitrogen, phosphate and potassium content of onion were higher in upland cultivated condition, but calcium, magnesium and sodium content of onion were higher in paddy cultivated condition. In distribution of onion bulb size, most of large sized onions were produced in upland cultivated condition. Average bulb production for seed harvesting were $63{\sim}70%$ higher in paddy cultivated condition than that of upland cultivated condition. The rotted rate of onion was about $27.2{\sim}34.6%$ in paddy, $37.5{\sim}51.4%$ in upland cultivated condition respectively, showed favorable result as the difference of $8.7{\sim}24.2%$ in paddy cultivated condition.

• Journal of Korean Society on Water Environment
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• v.32 no.2
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• pp.183-190
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• 2016

Monitored data (rainfall runoff and water quality) from 4 different paddy sites over 3 years were compared to analyze the effect of irrigation water management on irrigation supply and rainfall runoff quality in Korea. The system of rice intensification water management was adopted at one site (SRI) while the conventional water management method was used for rice culture at the other three sites (CT, SD and HD). The soil texture at SRI, CT and SD was sandy loam while that at HD was silt loam. The average reduction of irrigation supply at SRI compared with CT, SD and HD during the 3 years studied was 49%, 51% and 55%, respectively. The average event mean concentration (EMC) at SRI compared with that at CT, SD and HD was decreased by 35% (BOD), 44% (COD), 47% (SS), 19% (TN) and 38% (TP). The correlation between rainfall runoff and the measured non-point source (NPS) pollutants was very good in general. The comparison revealed that SRI water management significantly reduced both irrigation supply and EMC in rainfall runoff. Paddy NPS pollution was closely related to factors that induce runoff such as rainfall and irrigation supply. It was concluded that SRI management could be an effective and practical option to cope with both water shortage due to climate change and water quality improvement in rural watersheds. However, further studies are recommended in large irrigation districts for use in the development and implementation of NPS pollution policies since the data was collected from field sized paddies.