• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2005년도 동계 학술대회 논문집
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• pp.165-169
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• 2005

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.427-438
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• 1998

In Korea, rotary implements are mainly utilized in the tillage operation. The attitude control system for rolling phenominon of tractors, which in caused due to uneven ground surfaces and sinkage of tractor wheels, is one of the most important control systems in agricultural tractors. The attitude control system of a rotary implement, attached on tractors, was designed and fabricated in this study. The control system was largely composed of four main units; a setting unit, a detection unit, a controller and a hydraulic unit. The implement was controlled by control signals from a computer proportional to controlled errors, on/off action of two directional solenoide valve and lift cylinder on the right lift rod. Response characteristic experiments for the control system fabricated in this study were carried out indoors and outdoors. The results of experiments showed the response characteristics sufficient to use as the attitude control system of rotary implements for agricultural tractors.

• 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.

• 한국기계가공학회지
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• 제16권3호
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• pp.45-53
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• 2017

Disc harrow-type composite working implements of tractors are able to work almost 15km/hr. Soil reversing and plowing of agricultural fields are thereby faster than the existing rotavator speed of 2.5 km/h. In Korea, its supply process is being delayed because of the traditional tillage method of rotavator plowing operations. To develop products suitable for the domestic environment, an analysis and inspection was performed on the products of advanced specifications. 3D modeling was performed on main parts and frames using 3D scanner.

• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.22-27
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• 2003

An autonomous tractor requires not only automatic steering (automatic guidance) but also automated control of tractor functions and implement operations. Examples of tractor functions include engine throttle, transmission speed, and 3-point hitch position. Implement operations include tillage, planting, and cultivating. This article provides an overview of a map-based methodology used for the implementation of autonomous field operations of agricultural tractors. The procedure for developing autonomous field operation maps were presented, and several important issues in the implementation of map-based autonomous operations were discussed. These issues included combining field operation maps, position offset, and real-time sensing and update of field operation maps.

• Journal of Biosystems Engineering
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• 제38권1호
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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.

• 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.

• Journal of Biosystems Engineering
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• 제16권2호
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• pp.118-123
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• 1991

This study was conducted to investigate the influences of virtual hitch point (VHP) positions of a three-point hitch on the steering stability of agricultural tractors. The VHP locations were determined analytically from the linkage geometry and implement posture during the normal tillage operations. The maximum force applicable to the VHP was also determined under the given soil and power constraints. From these possible ranges of the VHP locations, a safe region for steering control was determined theoretically by using maximum applicable forces for the given tractor and implement combinations. With VHP positions within the safe region, tractor can maintain the minimum soil reaction forces, assumed 20% of the total tractor weight in this study, at the front wheels which is required for the steering control under the maximum traction conditions. This paper mainly concerns with mathematical developments for the determination of VHP locations and maximum forces applicable to the VHP for steering control. Experimental validation of the theory developed here follows as the second part of this study.

• 농업과학연구
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• 제48권3호
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• pp.617-627
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• 2021

In the field of on-road motor vehicles, the level for autonomous driving technology is defined according to J3016, proposed by Society of Automotive Engineers (SAE) International. However, in the field of agricultural machinery, different standards are applied by country and manufacturer, without a standardized classification for autonomous driving technology which makes it difficult to clearly define and accurately evaluate the autonomous driving technology, for agricultural machinery. In this study, a method to classify the autonomy levels for autonomous agricultural machinery (ALAAM) is proposed by modifying the SAE International J3016 to better characterize various agricultural operations such as tillage, spraying and harvesting. The ALAAM was classified into 6 levels from 0 (manual) to 5 (full automation) depending on the status of operator and autonomous system interventions for each item related to the automation of agricultural tasks such as straight-curve path driving, path-implement operation, operation-environmental awareness, error response, and task area planning. The core of the ALAAM classification is based on the relative roles between the operator and autonomous system for the automation of agricultural machines. The proposed ALAAM is expected to promote the establishment of a standard to classify the autonomous driving levels of self-propelled agricultural machinery.

• 환경영향평가
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• 제31권6호
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• pp.423-437
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• 2022

환경영향평가서 작성 및 검토 매뉴얼에 따라 훼손되는 수목의 일부를 이식하고 있다. 수목이 원래 서식하고 있는 산림에서 가이식장과 최종 이식장으로 이식하는 과정에서 고사하거나 생육이 불량한 등의 문제점이 지속적으로 제기되고 있다. 이 연구의 목적은 가이식장과 최종 이식장의 토양 특성을 파악하여 기존에 서식하던 산림 토양과의 차이를 분석하고, 이식한 수목의 생육에 적합한 토양으로 개선하는 방안을 제시하는 것이다. 10개의 환경영향평가 사업을 대상으로, 원래의 서식지인 주변의 산림지역, 훼손수목의 일부를 임시로 이식하고 있는 가이식장, 공사가 완료된 후 최종 이식을 하게 되는 공사장을 대표하는 지점에서 각각 2개씩, 총 60개의 토양을 샘플링하여 물리적 특성과 화학적 특성을 분석하였다. 물리적 특성 중에서 투수계수, 유효수분율, 경도, 화학적 특성 중에서 산도, 유기물함량, 전질소, 유효인산에서 집단 간 유의한 차이가 있는 것으로 나타났다. 공사장의 토양은 공사 장비로 인한 답압으로 주변의 산림보다 경도가 높고, 모래 함량이 많아 투수계수는 높으며 유효수분율은 낮아 식물이 필요한 토양 내 수분을 보유하지 못하고 배수되는 양이 많다. 경도가 높은 토양의 공극량을 증가시키고 물리적 구조를 개선하기 위하여 경운을 실시할 필요가 있다. 또한 토양의 물리성과 화학성을 함께 개선하기 위하여 토양 내 부숙된 유기물을 첨가한 후 우드칩이나 낙엽으로 표면을 덮어주는 것이 필요하다.