• 한국유기농업학회지
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• 제7권2호
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• pp.153-161
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• 1999

No-till direct-sown rice-wheat relaying cropping system has major advantages such as labor and cost saving by eliminating tillage and preparation of seed bed and transplanting. In this system, rice sowing was done simultaneously wheat harvesting. A paddy field experiment was conducted to evaluate effects of no-till years on soil microbial changes and soil physico-chemical characteristics with rice growth and development. Chemical fertilizers and agricultrual chemicals was not applied in no-till system. As the year in no-till direct-sown system the air permeability was increased and after water submerging soluble nitrogen was released Aerobic microbial-n was highest in May and then decreased after water irrigation. The population of aerobic soil microorganisms were steeply decreased after water submerging Soil microorganisms was decreased with the increased the soil depth. A month was needed for the seedling establishment in a no-tillage rice-wheat cropping system. Increased cropping years improved leaf greenness and leaf area index(LAI). But stomatal conductance(Gc) was higher in conventional cultivation system than no-till system. Stomatal conductance at panicle initiation stage was increased higher in conventional condition of leaves but the difference between conventional and no-till system was increased at heading stage. In no-till 4 years condition rice grain yield was spikelet numbers per panicle.

• 농업과학연구
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• 제49권4호
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• pp.937-948
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• 2022

Agricultural operations are performed in uneven environments by attaching an implement on the 3-point hitch of a tractor. A high load is thus placed on the 3-point hitch, and fatigue and failure of the hitch may occur during agricultural operations. In this study, a dynamic simulation model was developed to predict the load occurring on the eyebolt of a 3-point hitch, which is the main damaged component. The simulation model was developed and validated using agricultural data as simulation input and validation data. The dynamics model was developed using the specifications of a 78 kW class tractor. A measurement system was constructed to measure the simulation input and validation data. The simulation model was validated using a traction load on an eye bolt, which was measured during plow tillage operation. The measurement results showed that the average traction load on the left and right lower link and the top link were 8,099.97, 4,943.06, and 636.11 N, respectively. The simulation results and the measured traction load on the left eyebolt were respectively 610.30 and 597.15 N. The simulation results and measured traction load on the left eyebolt were respectively 1,179.78, and 1,145.06 N. The error between the simulation and measurement data was roughly 2% on the left eyebolt and 3% on the right eyebolt.

• 농업과학연구
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• 제50권3호
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• 한국작물학회지
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• 제44권2호
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• pp.97-101
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• 1999

No-till direct seeding cultivation of rice has major advantages such as saving of labor and cost by eliminating tillage, preparation of seed bed and trans-planting procedure compared to the conventional transplanting cultivation. A field experiment was conducted to evaluate the effects of straw treatment and nitrogen levels on the rice growth in no-till direct-seeding cultivation. Rice straw, vetch straw, and the mixture of both of the straws were mulched on the surface of soil before seeding while 4 levels of nitrogen fertilizer, 0, 7, 9, and 11 kkg/10a respectively, were applied at 3 split times, 3-weeks after sowing, 5-weeks after sowing and the panicle initiation stage. Mulching of vetch straw significantly reduced seedling establishment of rice which may be attributed to low oxidation-reduction potential of soil by vetch mulching treatment. Vetch straw increased the concentration of soil ammonium leading to an extension of the greenish leaf to panicle initiation stage. Agronomic nitrogen use efficiency (AD $E_{N}$) in heavy-mixed straw mulching plots was lower than other treatments. Grain yield and AU $E_{N}$ in the vetch treatment were less affected by fertilized N levels. Conclusively, it is suggested that heavy straw mulching was not efficient for rice seedling establishment and nitrogen usage.e.

• 한국토양비료학회지
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• 제35권1호
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• pp.1-11
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• 2002

옥수수 뿌리 성장에 미치는 토양통과 경운의 영향을 구명하기 위하여 3년 동안 일리노이 중부지방의 몇 개 토양통이 다른 옥수수 포장에서 뿌리 분포를 관찰하였다. 무경운과 경운된 포장에서 깊이 75 cm Minirhizotron 기술에 의하여 Video로 촬영을 한 후 뿌리 분포를 관찰하였다. 토양 경작층의 뿌리 분포는 생육 초기 증가하였고, 이후 늦은 여름에는 수분이 고갈되면서 감소하였다. 본 실험에서 뿌리 분포가 토양통에 따라 차이는 보이지 않았으나 토양통에 따른 분포의 차이는 토양의 유효수분 저장용량에 따라 차이를 보였다. 토양의 투수 속도가 빠른 무경운에서의 뿌리분포가 경운에서의 분포보다 많았다. 생육기간 중 심토 층에서의 옥수수 뿌리는 경운포장보다 전 작물의 뿌리통로를 이용하여 생장하는 무경운 포장에서 2-3주 일찍 관찰되었다. 결론적으로 옥수수 뿌리 분포는 토양통보다는 경운에 의한 영향이 클 것으로 생각되었다.

• 농업과학연구
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• 제46권4호
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• pp.723-735
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• 2019

The power-train is the most important component of an agricultural tractor. In this study, the strength of the driving gear transmission of an 82 kW-class tractor was analyzed using equivalent torque during plow tillage. The load measurement system consisted of an engine revolution speed sensor, torque-meters, revolution speed sensors for four axles, and pressure sensors for two hydraulic pumps. The load data were measured during plow tillage for four speed stages: F2 (2.78 km/h), F5 (5.35 km/h), F7 (7.98 km/h), and F8 (9.75 km/h). Aspects of the gear-strength such as bending stress, contact stress, and safety factors were analyzed under two torque conditions: the equivalent torque at the highest plow load for the F8 speed stage and the maximum engine torque. The simulation results using KISSsoft showed that the maximum engine torque conditions had a lower safety factor than did the highest equivalent torque condition. The bending safety factors were > 1 at all gear stages, indicating that gear breakage did not occur under actual measured operating conditions, nor under the maximum torque conditions. However, the equivalent torque condition in the contact stress safety factor was > 1, and the maximum torque condition was < 1 at the first gear pair. The method of analysis using the equivalent torque showed lower stress and higher safety factor than did the method using maximum torque. Therefore, when designing a tractor by applying actual working torque, equivalent torque method would support more reliable product development.

• 한국작물학회지
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• 제53권4호
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• pp.413-416
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• 2008

The cultivation of green manure crop is considered as a good management practice by increasing soil organic matter and fertility levels. This experiment was conducted to improve the soil environment under rice-based cropping system at paddy soil (fine loamy, mixed, nonacid, mesic, family of Aeric Fluventic Haplaquepts) in National Institute of Crop Science (NICS), Korea in 2006 to 2007. The variation of soil temperature in green manure plots was lower than without green manure (control) during spring season (April to May). The temperature variation of no tillage plot (broadcast before rice harvest) was the lowest among treatments. After green manure cropping, the soil bulk density and porosity ratio were improved at the top soil. The production of green manure was the highest athairy vetch and barley mixture plot by partial tillage. However, mixture treatment had no improvement on soil organic matter. After rice cropping with green manure application, soil quality was improved such as soil physical properties except mixture treatment. Therefore, we suggest that soil quality should be improved by green manure cultivation under rice-based cropping system.

• 농업과학연구
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• 제43권4호
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• pp.665-669
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• 2016

Analysis of the load on the tractor during field operations is critical for the optimal design of the tractor. The purpose of this study was to do a load analysis of an agricultural tractor during plowing and harrowing. First, a load measurement system was developed and installed in a 71 kW agricultural tractor. Strain-gauges with a telemetry system were installed in the shaft located between the axles and the wheels, and used to measure the torque of the four driving axles. Second, field experiments were conducted for two types of field operations (plowing, harrowing), each at two gear levels (M2, M3). Third, load analysis was conducted according to field operation and gear level. At M2 gear selection for plowing, the maximum, minimum, and average (S. D.) torque values were 13,141 Nm; 4,381 Nm; and 6,971 Nm (${\pm}397.8Nm$, respectively). For harrowing, at M2 gear selection, torque values were, 14,504 Nm; 1,963 Nm; and 6,774 Nm (${\pm}459.4Nm$, respectively). At M3 gear selection for plowing, the maximum, minimum, and average (S. D.) torque values were,17,098 Nm; 6,275 Nm; and 8,509 Nm (${\pm}462.4Nm$, respectively). For harrowing at M3 gear selection, maximum, minimum, and average (S. D.) torque values were, 20,266 Nm; 2,745 Nm; and 9,968 Nm (${\pm}493.2$). The working speed of the tractor increased by approximately 143% when shifted from M2 (7.2 km/h) to M3 (10.3 km/h); while during plow tillage and harrowing, the load of the tractor increased approximately 1.2 times and 1.5 times, respectively.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.141-151
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• 2020

The aim of this study was to analyze the safety factor of range-shift gear pairs on multi-purpose agricultural implement machinery for an optimal design of a transmission system. Gear-strengths such as bending and contact stress and safety factors were analyzed under three load conditions: an equivalent engine torque at plow tillage, a rated engine torque, and the maximum engine torque. Root and contact safety factor were calculated to be 3.88, 5.14, 2.24, 2.11, 2.21, 0.99 and 0.78, 0.94, 0.65, 0.68, 0.84, 0.85, respectively, under equivalent engine torque condition at the plow tillage. The root and contact safety factor were calculated to be 1.91, 2.53, 1.10, 1.04, 1.07, 0.48 and 0.55, 0.66, 0.46, 0.48, 0.59, 0.59, respectively, under rated engine torque condition. The root and contact safety factor were calculated to be 1.60, 2.11, 0.92, 0.87, 0.90, 0.40 and 0.51, 0.61, 0.42, 0.44, 0.54, 0.54, respectively, under the maximum engine torque condition. The multi-purpose agricultural implement machinery could be conducted under plow tillage operation. However, gear specifications for tooth surface need modification because the gear surface would be broken at all driving conditions as safety factors are lower than 1.

• 한국초지조사료학회지
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• 제29권3호
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• pp.211-216
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• 2009

본 연구는 옥수수 재배지에서 경운방법과 가축분뇨의 시용이 사료용 옥수수의 생산성 및 질소의 용탈에 미치는 영향을 알아보기 위하여 국립축산과학원 초지사료과 시험포장(천안)에서 lysimeter를 이용하여 2008년 4월부터 8월까지 실시하였다. 시험구 배치는 분할구배치법으로 경운방법(경운과 무경운)을 주구로 하였으며, 가축분뇨의 종류(화학비료, 우분퇴비 및 돈분퇴비)를 세구로 하였다. 가축분뇨의 시용은 화학비료구는 표준시용량(N-$P_2O_5-K_2O$)으로 200, 150 및 150kg/ha을 시용하였으며, 우분퇴비와 돈분퇴비의 경우 화학비료구의 질소대비 100%를 전량 기비로 시비하였다. 경운방법에 따른 옥수수의 건물생산성과 뿌리의 무게를 측정한 결과 경운 처리구에서 무경운 처리구보다 높게 나타났으나 유의적인 차이는 없었다. 가축분뇨 시용에 따른 옥수수의 건물생산성은 화학비료 > 우분퇴비 > 돈분퇴비 순으로 유의적으로 높게 나타났으며 (p<0.05), 뿌리 무게는 화학비료구와 우분퇴비구에서 돈분퇴비구 보다 유의적으로 높게 나타났다(p<0.05). 가축분뇨 시용에 따른 경직경, 당도는 화학비료구와 우분퇴비구에서 돈분퇴비구 보다 유의적으로 높았다(p<0.05). 옥수수의 생산성과 생육특성에 있어 경운방법과 가축분뇨 시용에 따른 유의적인 교호작용은 나타나지 않았다. 경운방법에 따른 평균 $NO_3$-N의 용탈은 경운 처리구에서 무경운 처리구보다 약간 높았으나, 통계적인 유의차는 없었다. 하지만 가축분뇨 시용에 따른 $NO_3$-N의 용탈은 화학비료구에 비해 유의적으로 낮게 나타났다(p<0.05). 본 시험의 결과 사료작물을 재배에서 경운방법이 옥수수의 생산성 및 $NO_3$-N 용탈에 미치는 영향은 크지 않았으며, 화학비료의 질소 대비 100%의 가축분뇨를 시비하였을 경우 용탈되는 $NO_3$-N의 농도가 높지 않아 수질에 미치는 영향이 미미하였다.