• The Korean Journal of Ecology
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• v.18 no.4
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• pp.471-481
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• 1995

The weed population dynamics as affected by contrasting conventional tillege (CT) and no-tillage (NT) practices with a minimum herbicide application was studied in Athens, Georgia, U.S.A. Common chickweed (Stellaria media) was the most common spring weed while johnsongrass (Sorghum halepense), sicklepod (Cassia obtusifolia), and pigweed (Amaranthus retroflexus) accounted for 89∼97％ of net production during summers of 1983 and 1984. Total weed production in summer of 1984 was 2∼5 times greater than that of 1983. Weed production was greater in NT plots than in CT plots in summer of 1983, but reverse was the case in summer of 1984. In spring, net production in NT plots was greater than that in CT plots, especially, in 1985. Species diversity was consistently higher in NT plots, but in the wet summer of 1984 the pattern was different, with higher diversity in CT plots. Weed species diversity was higher in the spring rye crop than in the summer grain sorghum crop. The larger but less diverse weed populations in summer of 1984 indicated that these populations experienced competitive exclusion. Under the favorable summer moisture conditions the three dominant species grew so vigorously and quickly as to exclude many less common species that were able to survive under the drier conditions in 1983. The three dominant species not only excluded other weeds in 1984 but also greatly reduced crop production. The perennial johnsongrass was equally successful, or even more so, in CT plots as in NT plots. Plowing did not kill johnsongrass rhizomes but tended to break them up, thus increasing the number of individual plants that appear after the plowing. It means that johnsongrass was not controlled by the plowing. In summer of 1983, a moderate amount of weedy growth was maintained with a minimum amount of gerbicide application in NT and CT plots. It is possible that a small mixed weed population would be beneficial by providing cover for predatory and parasitic arthropods, and by reducing soil temperature and moisture losses.

• Journal of Biosystems Engineering
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• v.9 no.2
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• pp.37-47
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• 1984

Using the soil bin systems, this study was carried out to analyze the effects of the angular and tilling speed of the rotary shaft with the edge curves which were $30^{\circ}$ and $40^{\circ}$, and the edged blade which were single and double, on the torque requirement of rotary tillage. In the analyses, we developed the mathematical models for the torque requirments of rotary tillage, and analyzed the optimum conditions of each variable for the minimum tillage torque requriements. The results of the study were summarized as follows. 1. The required tilling torque by one rotary blade has the minimum value when the tilling speed of the rotary blade was low, and the revolution of the rotary blade was fast, in general. 2. The torque requirements of single edged blade was decreased to about 81% in comparing with that of double edged blade of which the edge curved angle was $40^{\circ}$ and the tilling speed was 29.40 cm/sec. But, for the mean values, the maximum torque requirements were decreased to 45%, and the mean torque requirements were decreased to 35%. 3. For the edge curved angle, the torque requirements of ${\theta}=40^{\circ}$ were 48% more than that of ${\theta}=30^{\circ}$ in the maximum tilling torque in case that the rotary blade were double edged blade. but, there was not a difference when the rotary blades were single edged blade. The mean tilling torques of ${\theta}=40^{\circ}$ were 6% more when the rotary blade was double edged blade, and were 11% less at single edged blade, than that of ${\theta}=30^{\circ}$. 4. In order to reduce the torque requirements for tilling, the optimum revolutions of the rotary shaft were analyzed as that 204-240 rpm for the double edged blade and 280-320 rpm for the single edged blade.

• Journal of Biosystems Engineering
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• v.38 no.1
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• pp.1-8
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• 2013

Purpose: Path planning and tracking algorithms applicable to various agricultural operations, such as tillage, planting, and spraying, are needed to generate steering angles for auto-guidance tractors to track a point ahead on the path. An optimal coverage path algorithm can enable a vehicle to effectively travel across a field by following a sequence of parallel paths with fixed spacing. This study proposes a path generation and tracking algorithm for an auto-guided Korean tractor with a tillage implement that generates a path with C-type turns and follows the generated path in a paddy field. A mathematical model was developed to generate a waypoint path for a tractor in a field. This waypoint path generation model was based on minimum tractor turning radius, waypoint intervals and LBOs (Limit of Boundary Offsets). At each location, the steering angle was calculated by comparing the waypoint angle and heading angle of the tractor. A path following program was developed with Labview-CVI to automatically read the waypoints and generate steering angles for the tractor to proceed to the next waypoint. A feasibility test of the developed program for real-time path tracking was performed with a mobile platform traveling on flat ground. The test results showed that the developed algorithm generated the desired path and steering angles with acceptable accuracy.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.3
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• pp.165-171
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• 2014

Assessment of sustainable production on a cropland can help to determine the most proper management practices. In this study, we evaluated the sustainable production on paddy field treated with green manure crops using sustainability index which based on nutrient index, microbiological index, and crop index related to nutrient-supplying capacity. Especially choosing appropriate indicators from a minimum data set (MDS) were used the principal components analysis (SI-2) as well as expert opinion (SI-1) usually used in sustainability index. Six treatments including the two tillage treatments and two green manure crops were investigated as follows; (i) moldrotary + rotary tillage without green manure crop (Con), with (ii) hairy vetch (Con-HV), and (iii) hairy vetch + green barely (Con-HV+GB), (iv) rotary tillage without green manure crop (Rot), with (ii) hairy vetch (Rot-HV), and (iii) hairy vetch + green barly (Rot-HV+GB). Con-HV and Rot-HV in SI-1 were maintained sustainability while Rot-HV and Rot-HV+GB in SI-2. Especially, treatments (Con and Rot) without green manure crops were more unsustainable than with green manure crops because of the low value of microbiological and crop index than with green manure crops. Meanwhile, sustainability indices and grain yield had the high correlation values ($R^2=0.756$ and 0.928 in SI-1 and SI-2, respectively). These results meant that application of green manure crops such as hairy vetch could improve both yield and soil quality in paddy.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.238-243
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• 2003

쌀은 전 세계에서 매년 약 4억 톤이 생산되어 세계인구의 약 45%에게 주식으로 제공되고 있다. 우리나라에서는 쌀 농사가 농업소득의 약 44%를 차지하는 농가의 주 소득원으로 경제적 비중이 크다. 또한 WTO 개방경제 체제에서는 쌀 생산농가가 생존하기 위해서는 생산비 절감을 통한 가격경쟁력 제고와 품질향상을 통한 소비자 선호도 확보가 가장 중요한 과제이다. 지금까지 우리나라의 벼농사는 생산비 절감이나 품질향상보다는 수량증대에 치중하여 쌀 산업의 국제경쟁력은 매우 취약한 실정이다. (중략)

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.270-275
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• 2013

Hairy vetch can fix nitrogen from the atmosphere as a leguminous cover crop. This research was carried out to determine optimum seeding method of hairy vetch and application effect in paddy. Field experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts) from Sep. 2011 to Oct. 2012 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Hairy vetch used in the study was 'Cheongpyungbora', developed by National Institute of Crop Science. Seeding methods of hairy vetch consisted of Broadcasting Before Rice Harvesting (BBRH), Partial Tillage Seeding (PTS), Minimum Tillage Seeding (MTS), No Tillage Seeding (NTS), and Drill Seeding (DS). Both MTS and NTS showed the highest biomass among the seeding methods. The rice yield of MTS and NTS significantly increased compared to conventional fertilization (CF). Also soil properties including organic matter and bulk density were improved by incorporation of hairy vetch. Therefore, we suggested that MTS and NTS could be used to produce hairy vetch and rice in paddy.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.95-101
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• 1986

A computer-controlled automatic vibratory tillage test equipment which attained minimum draft and power was developed. Three control program modes were developed and tested with this equipment. A computer simulation investigated the control performances of the above modes with the following primary results. 1) All of the three control modes converged to the same steady state when the velocity ratio was kept constant. 2) The control mode in which the blade frequency was twice of the soil shearing frequency (frequency control mode) showed optimum control with minimum draft and power, and also had greatest velocity convergence. 3) Results of the simulations showed the frequency control mode to have achieved the best control performance. The fluctuation of the draft reduction was less than 10% at various cutting depths and soil moistures.

• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.613-627
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• 2019

The purpose of this study was to design a powertrain for a 78 kW AWD (all wheel drive) electric tractor by analyzing the combination of various reduction gear ratios on a commercial motor using data from actual agricultural work and driving conditions. A load measurement system was constructed to collect data using wheel torque meters, proximity sensors, and a data acquisition system. Field experiments for measuring load data were performed for two environmental driving conditions (on asphalt and soil) and four agricultural operations (plow tillage, rotary tillage, loader operation, and baler operation). The attached implements and gear stages were selected through farmer surveys. The range of the reduction ratio was determined by selecting the minimum reduction ratio needed to satisfy the torque condition required for agricultural operations and the maximum reduction gear ratio to satisfy the maximum travel speed. The minimum reduction gear ratio selected was 57 in consideration of the working load condition and the maximum reduction gear ratio selected was 62 considering the maximum running speed. In the range of the reduction gear ratio 57 - 62, the selected motor satisfied all working torque conditions. As a result, the combination of the selected motor and reduction gear ratio was applicable for satisfying the loads required during agricultural operation and driving operation.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.688-695
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• 2011

This study was carried out for some survey about soil compaction in the multi-cropping system of paddy field. Investigated sites were 90 farmer's fields in south-eastern part of Korea. The tillage practices season was different according to cropping system of paddy; in spring for mono rice cultivation and in autumn for the multi-cropping field. The average tillage depth in investigated sites was about 25 cm, however, it is different between the farmer's tillage practices and soil characteristics. It is high correlation to tillage deep and minimum resistance of penetration. The reaching soil deep to maximum resistance of penetration was about 27 cm, and average penetration resistance of the deep is 1.8~2.0 MPa for moderately fine-textured soils and more than 3.0 MPa for moderately coarse-textured soils. The difference of penetration resistance between cultivating and compacted layer was in order to sandy loam > clayey loam > clayey, and the difference was lesser in poorly drained soils than somewhat poorly ones. In the rice mono cropping field, the maximum resistance in no-tillage for 15 years was 1.18~1.25 Mpa at 20~25 cm in soil deep, however, the resistance of field with every year tillage practices was 2.03~2.21 Mpa. In the extremely compacted sandy loam textured soils, the penetration resistance at 30 cm in soil depth was drastically reduced by the subsoil from 5.2 Mpa to 3.2 Mpa, and the watermelon root in plastic film house was deep elongated.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.3-8
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• 2002

쌀은 전 세계에서 매년 약 4억 톤이 생산되어 세계인구의 약 45%에게 주식으로 제공되고 있다. 우리나라에서는 쌀 농사가 농업소득의 약 44%를 차지하는 농가의 주 소득원으로 경제적 비중이 크다. 또한 WTO 개방경제 체제에서는 쌀 생산농가가 생존하기 위해서는 생산비 절감을 통한 가격경쟁력 제고와 품질향상을 통한 소비자 선호도 확보가 가장 중요한 과제이다. 지금까지 우리나라의 벼농사는 생산비 절감이나 품질향상보다는 수량증대에 치중하여 쌀 산업의 국제경쟁력은 매우 취약한 실정이다. 손 모내기에서 중묘 기계이앙 기계기술이 확립되어 확대보급 되었고 이보다 육묘비용 및 노력을 절감할 수 있는 어린 모 재배 기술이 보급되기 시작하였으나, 미국 등 선진국의 벼농사 노동 투하시간 3.5시간/㏊에 비하여 우리나라는 328시간/㏊ 쌀 생산비는 미국의 2,018천원/㏊에 비하여 우리나라는 5,105/천원㏊로 월등히 높아 노동 투하시간을 획기적으로 줄일 수 있는 기계기술 개발이 요구되고 있다. (중략)