• Journal of Korean Society of Rural Planning
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• v.11 no.2 s.27
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• pp.9-19
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• 2005

The purpose of this study is to analyze the potential soil loss and hazard zone by the Revised Universal Soil Loss Equation(RUSLE) for preservation and management of land resources which is the base of ecosystem, and to grasp the relationship between RUSLE factors in the Nakdong River Basin. All thematic maps used in RUSLE are constructed through GIS and spatial analysis method derived from digital topographic maps, detailed soil maps, land-cover maps, and mean annual precipitation of 30 years collected respectively from National Geographic Information Institute, National Institute of Agricultural Science and Technology, and Ministry of Environment. The slope length of LS-factor that takes much times by the study area's wideness was calculated automatically through AML(Arc Macro Language) program developed by Van Remortel et al.(2001, 2003). The results are as follows; First, according to the soil loss estimation by the RUSLE, it shows that approximately 82% of the study area have relatively lower possibility of soil loss which is the 1 ton/ha in annual soil loss. While, 9.4% ($2,228km^2$) needed intensive and continuous management for soil loss. Because the amount of their annual soil loss was greater than 10 ton/ha that is optimum level suggested by Morgan(1995). For these areas, the author believe that a new approach which can minimize environmental impacts from soil loss through improvement of cultivation process and buffer forest zone should be applied. Second, according to the relationship between the RUSLE factors, topographical(LS-factor) and cover management(C-factor) conditions have a lot of influence on soil loss in case of the Nakdong River Basin. However, because of RUSLE factor's influence that affect to soil loss might be different based on the variety of spatial hierarchy and extent, it is necessary to analyze and evaluate factor's relationship in terms of spatial hierarchy and extent through field observations and further studies.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.257-265
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• 2015

This experiment was carried out to determine the optimum planting density for rice pot seedling cultivation in wheat-rice double cropping system in Honam plain area. A mid-late maturing rice variety 'Chinnong' was raised in pot seedling tray and conventional tray for 30 days, and then transplanted on June 25 in 2012 and 2013. Four different planting densities (15.2, 18.9, 21.6, and 25.3 hills per $m^2$) in pot seedlings were applied as treatment. Conventional tray seedling was implicated as control at a single planting density of 27.8 hills per $m^2$. In this experiment, the number of effective tillers was increased as planting density increasing, but stem diameter was decreased. Pot seedling showed higher stem diameter and effective tillers than the control. Heading dates of pot seedling plots were not significantly different between the planting densities but 2 days faster than the control. Culm length, number of panicles, panicle length, and ripening grain ratio were higher in pot seedling compared to the control, but 1000-grain weight showed no significant difference. Milled rice yields in pot seedlings ranged from 5.19 to $5.43\;t\;ha^{-1}$, and the highest yield was observed in 21.6 hills per $m^2$. Head rice ratios in pot seedlings and the controls were not significantly different. Above results on planting density of rice pot seedling cultivation would be applicable to wheat-rice double cropping and also to late transplanting cultivation of rice single cropping.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.4
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• pp.82-95
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• 1980

This paper complies the results of the studies so far made on the subsoil improvement of subsurface drainage systems for wet paddy fields (those were located in the Gum-Ho area in Kyung Buk province) which had poor permeability and a high water table. In general, a drainage problem is an excess of water on the ground surface which can effect the productivity and bearing capacity of the soil. With drain pipe systems, (According to their depths and spacing) it may be possible to correct that problem. The experimentation consisted of three test plots, two of which included drain pipe systems with varing depths and width spacing of the pipes. The third plot (C) was an ordinary plot being exempt of a drain pipe system. In detail, the depth of plot A was 80 cm, and the width spacings began at 2. Om and increased by 2. Om up to 10. 0m. The depth of plot B was 60cm and the width spacing was the same as plot A. These tests were performed to research specific details; such as crop yeild, bearing capacity of the soil, the amount of underdrainage, surface cracks, root distribution, the water table level, the consumptive water depth and the soil moisture content. The test period lasted three years, from 1977 thru 1979. The results obtained were as follows: 1. During the test period, the weather conditions for the area tested were in accordance with the annual average for that area. Furthermore the precipitation factor during the spring cultivation season, the intermediate drainage period and the harvest drainage period was of optimum conditions for controling surface cracks, because of less precipitation than evaporation. 2. The difference in the level of the ground water table in plots A and B was hardly noticable, but the difference in the test plots and the ord. plot was greatly noticable. The test plots (A, B) were 30 to 40cm lower than the ordinary plot. On the whole, the ground water table of the ord. plot always stayed at a level of 15-20cm beneath the surface of the soil, the ground water table of the test plot A showed The difference in the depth of the pipe lower than the test plot B, while the test plots showed a remarkable descending effect. 3. The soil temperature in plot A was slightly core than in plot B with a difference of 0. 47$^{\circ}$C, but plot A was 1. 6$^{\circ}$C higher than the ord. plot during the flooding period, but after drainage the temperature difference climed to 2. 0$^{\circ}$C. 4. During the 3rd test year, the values of the cracks were recorded with the values of 59cm in plot A, 42cm in plot B and 15cm in the ordinary plot. Plots A and B had increased 2.5 times the value of the first year while the ordinary plot had remained the same. 5. The root weight of the rice was measured at a value of 77.2 gr. for plot A, 73.5 gr. for plot B and 65.3 gr. for the ord. plot. Therefore, the root growths in plots A and B were much more energetic than in the ord. plot. 6. The consumptive water depth measured during the 3rd year resulted in the values of 26. 0mm per day for plot A, and 24.9 mm per day for plot B, respectively. Therefore, both plot A and plot B maintained the optimum consumptive water depths, but the ordinary plot only obtained the value of 12.3 mm per day, which clearly showed less than the optimum consumptive water depth which is 20 to 30 mm/day. 7. The soil moisture content is in direct relationship to the ground water level. During drainage, test plot A decreased in its ground water level much more rapidly than the other two plots. Therefore, plot A had a much less soil moisture content. But this decreased water level could be directly effected by the weather conditions. 8. The relationship between the bearing capacity and the soil moisture content were directly inversely proportional. It can be assumed that the occurence of soil creaks is limited by the soil moisture content. Therefore, the greater the progress of the surface creaks resulted in a greater bearing capacity. So, tast plot A with a greater amount of surface cracks than the other test plots resulted in a greater bearing capacity. But, the bearing capacity at the harvest season could be effected by the drainage during the intermediate drainage period and by the weather conditions. 9. Comparing the production of the test plots to the ord. plot; there was an increased value of 840kg for plot A, 755kg for plot B and 695kg for the ord. plot in the rough rice. Therefore, plot A had an increase of 20% over the ordinary plot. The possibility of producing double crops was investigated. The effects on barley production in the test plots showed a value of 367kg per 10 acres, which substantiated the possibility of double crops because that value showed an increased value over the average yearly yield for those uplands. 10. So as a result, it can be recommended that by including a drain pipe system with the optimum conditions of an (80cm centimeter) depth and a (l0m) spacing will have a definite positive effect on the over all production capacity and quality of wetpaddy fields.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.333-342
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• 2010

For the energy-saving production of fresh vegetables in poor environment such as the Antarctic, a container-type plant factory was designed and developed. To maximize space usage of the 20 feet container ($L5.9m{\times}W2.4m{\times}H2.4m$), a three-level hydroponic cultivation system was installed and the nutrient solution was supplied by bottom watering. Using this system, 3 lettuce cultivars were grown under different the light source (light intensity). After 2 weeks from the transplanting, fluorescent lamp ($145\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed the best fresh weight of top part and leaf area. However, After 4 weeks, fluorescent lamp plus metal halide lamp ($150\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) led to the optimum growth of the each lettuce cultivar. The cultivar, 'Cheongchima', showed the best fresh weight of top part and leaf area, followed by 'Jeokchukmyeon' and 'Lollo rosa'. The chlorophyll concentrations (SPAD) showed no significant difference among the sources of lights. However, 'Cheongchima' showed relatively high chlorophyll concentration. With the above results, we found that the growth of lettuce is depend on light intensity and even at same intensity, the growth is different among the cultivars. Therefore, the selection of optimum cultivar should be considered in the plant factory system that has only weak light density.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.12
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• pp.31-36
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• 1972

These studies were carried out to find out the proper plant spacing and the optimum amount of nitrogen for maximum yield, on the occasion of early planting with creen vegetable (soybean for cook with rice) at the low temperature in early spring. The plant spacing were applied in 5 levels (50cm$\times$5cm, 50cm$\times$10cm, 40cm$\times$10cm, 30cm$\times$10cm and 30cm$\times$20cm) and the amount of nitrogen were applied in 4 levels (non, standard, twice and triple-amount), The triple super phosphate and potassium chloride were applied only in standard amount. The promotion of flowering was practised by the short-day treatment for 10 days (11 hr. a day). The variety examined was the early maturing one, HOKKAI # 1. and the results are as follow. 1. The plant spacing for maximum yield by the promotion of branch, pod and garin per a plant recognized the fact that there were 2 levels (50cm$\times$10cm and 30cm$\times$20cm planting method) and the maximum yield by the promotion of pod and grain per area showed the fact that there were 2 levels (50cm$\times$5cm and 30cm$\times$10cm planting method) in narrow planting method. 2. The optimum amount of nitrogen applied for maximum yield of pod and grain per area recognized w hat was sufficient as standard amount.

• Journal of agriculture & life science
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• v.51 no.3
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• pp.19-27
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• 2017

This study was conducted to investigate the optimum transplanting method for increasing the rice yield and quality by early transplanting cultivation in Gyeongnam plain area. This examination used of the transplanting method of planting distance($30{\times}14$ and $30{\times}18cm$) with number of seedlings(3, 5 and 7 plants). In high planting density($30{\times}14cm$), the number of tillers was increased while plant height was decreased as the planting number increases. On the other hand, the plant height and number of tillers were increased as planting number increases in low planting density($30{\times}18cm$). However, the number of grain per panicle was increased while the number of panicle was decreased as the planting number decreases. The number of panicle and the number of grain per panicle was increased as the planting distance increase. The yield of rice, when transplanted in the distance of $30{\times}14cm$ with 3 plants, was higher than the other treatment. Head rice ratio and head rice yield was the highest when transplanted in the distance of $30{\times}18cm$ with 3 plants(403 kg/10 a). The protein content was decreased and Toyo taste value was improved when transplanted in the distance of $30{\times}18cm$. Taken together, the best transplanting method for early transplanting cultivation was low planting density($30{\times}18cm$) with 3 plants in Gyeongnam plain area.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.123-131
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• 1999

To get the basic information for the improvement of the optimum levels of upland soil fertility and fertilizer application, the soil samples in two hundred fifteen site were collected from the major condiment vegetable cultivation areas such as red pepper, garlic and onion fields. Physico-chemical properties of the soil samples were investigated. Soil texture distribution of soil samples in red pepper, garlic and onion cultivation areas was in order of loam (L), sandy loam (SL), silt loam (SiL) and clay loam (CL) (35.4, 31.6, 14.9 and 7.0%, respectively). The average pH of soil in garlic and onion cultivation areas were over pH 6.0, whereas in red pepper was under pH 5.5. The frequency distribution of soil pH in total sampling sites were 58.7% in under pH 6.0 and 21.4% in below pH 5.0, in contrast to 10.3% in over pH 7.0. The organic matter contents were in the range of $20{\sim}30g\;kg^{-1}$, and the onion field soils was a little higher than those in red pepper or garlic. The available phosphate contents were in the range of $719{\sim}746mg\;kg^{-1}$ and were not different among in red pepper, garlic and onion. The frequency distribution of available phosphate in total sampling sites were found 62.8% of above $600mg\;kg^{-1}$, which was over the standard level for upland soil improvement, and then 22.3% was exceeded $1,000mg\;kg^{-1}$, especially. In the exchangeable cations, the K and Ca contents in garlic (1.27 and $9.11cmol\;kg^{-1}$) and onion (1.20 and $8.39cmol\;kg^{-1}$) were higher than in red pepper (0.96 and $5.87cmol\;kg^{-1}$), respectively. The Mg contents in garlic field soils ($2.17cmol\;kg^{-1}$) were higher than those in red pepper and onion (1.51 and $1.80cmol\;kg^{-1}$). This exchangeable K, Ca and Mg contents were higher than the standard level for upland soil improvement. The contents of microelement were ranged in $54.3{\sim}60.1mg\;kg^{-1}$ for Fe, $31.3{\sim}42.3mg\;kg^{-1}$ for Mn, $1.7{\sim}2.3mg\;kg^{-1}$ for Cu and $4.8{\sim}5.5mg\;kg^{-1}$ for Zn, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.285-290
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• 1983

Two methods were tested to establish the cropping period for rice cultivation using the meteorological data. The Hanyu-Uchijima method was based on the normal average temperature to select the earliest possible transplanting date (ETD), the earliest heading date (EHD), the optimum heading date (OHD) and the latest maturing date (LMD). The probability method was based on the temperature occurrence probability. The cropping period based on the probability method gave higher stability than H-U method for year variability. The ETD by the probability of 75 to 90 percents was May 12 to 22 for northern part of Korea, May 15 to 25 for east coastal area and May 4 to 16 for southern part, respectively. In Chuncheon area, the rice varieties requiring more than 1700 degree-days from transplanting to heading might not be appropriate due to low temperature condition and those requiring 1900 degree days were not allowable in Kangreung area. The OHD was July 30 to August 8 in northern part of the country and August 11 to 16 in southern part for Tongil varieties which demand higher temperature than common Japonica varieties. The OHD for Japonica varieties were 5 to 7 days later than Tongil varieties. The LMD was September 30 to October 2 in northern part, October 13 to 14 in east costal area and October 7 to 14 in southern part, and was earlier than the first frost date.

• Applied Biological Chemistry
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• v.37 no.3
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• pp.161-167
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• 1994

Soluble solids $(^{\circ}Brix)$, acid content and vitamin C content of Citrus miyakawa unshiu and C. okitsu unshiu juice harvested middle of November 1993 in Seuho-Dong and Topyung-Dong, Seogwipo-si, south area of Cheju were $10.7{\sim}11.0$, 1.04% and $41.19{\sim}44.94\;mg/100\;g$ juice, respectively. Carbohydrate was consisted of about 1/2 sucrose, 1/4 glucose, and 1/4 fructose. Fruit weight, peel thickness, soluble solids, pH, acid content and Brix/Acid ratio had a good correlation in linear function with increasing fruit size, respectively. However, hardness and edible part ratio were not showed correlation with increasing fruit size. Middle size of citrus fruit was favorable to panelists, and the citrus peel color of red yellow was more favorable than pale yellow color in sensory evaluation. Sensory evaluation score showed a linear correlation among citrus fruits of C. okitsu unshiu produced in Namwon-ri, Seuho-Dong, Seogwipo-si, south area of Cheju, and that of Chochun-ri, Ara-Dong, Cheju-si, north area of Cheju, and the score was higher according to citrus fruit produced in optimum cultivation area. With increasing Brix/Acid ratio of citrus juice, high sensory evaluation score was gained in panelists. These data obtained are supposed to be applied to the quality evaluation of Citrus unshiu produced in Cheju.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.1
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• pp.75-84
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• 2012

Mechanized operation model and mechanical cultivation technology for winter barley, rye, Italian ryegrass and sudan grass wrap silage production system at the paddy field for cropping system was developed. Also, a series of experiment were performed and lots of data were collected and analyzed to develope mechanical technology, coverage area, and optimum size of the farm (break-even point) for wrap silage production system. The coverage area for winter barley or rye wrap-silage production system is determined around 61.9, 73.4, 77.5, 88.2 ha in the case of drill seeding and different ripening species by tractor power 50, 75, 100, 130 ps, respectably. The break-even point of the farming size is analyzed as 20 ha and its production cost is estimated around 367, 383, 430, 443 won/TDN-kg in the case of winter barley wrap-silage by tractor power 50, 75, 100, 130 ps, respectably. The break-even point of the farming size is analyzed as coverage area and its production cost is estimated around 237, 215 won/TDN-kg in the case of winter barley wrap silage and sudan grass by the tractor power 50, 100 ps, respectably.