• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.195-202
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• 2000

This study was conducted to recognize a possibility that cone index can be used as a means of evaluating the tillage workability. Cone indexes were measured every 24 hours after rainfall at the experimental plots, and the rotary and plowing operations were conducted at the same time. The workability was evaluated on a basis of three categories of good, fair and poor depending on the quality of the performed works. Although the workability was affected by many factors such as soil type, moisture content ground slope and weather condition, the duration and amount of rainfall were of most influence. Results of the study showed that a good workability was resulted from the cone indexes greater than an average of 552 kPa for rotary operations and 671 kPa for plowing operations. Fair work was obtained with cone indexes greater than an average of 331 kPa for rotary operations and 459 kPa for plowing operations. The cone indexes less than an average of 171 kPa and 149 kPa resulted in poor workabilities for rotary and plowing operations, respectively. The experimental results may provide a general guideline for evaluating the tillage workability by cone index.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.127-133
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• 2015

The error motion of a machine tool spindle directly affects the surface errors of machined parts. Those are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions for rotary units such as a spindle and rotary table are suggested. To estimate the error motions of the rotary unit, waviness of bearings and external force model were used as input data. The estimation model considers geometric relationship and force equilibrium of the five degree of the freedom motions.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.277-283
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• 1993

The model of rotary tillers under side loads established here is statically in determinate system. By means of FEM method, the deformation of side gearbox and right side board are calculated. Therefore the side deformations of rotary tillers under different lateral loads are discussed systematically. The results show that the rotary tiller system would bear the loads and deform unequally. Author's calculation also indicates that the lateral deforming values of right side board and side gearbox are almost the same, and more than 98% of the loads is born by the side.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.2
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• pp.147-155
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• 2012

Wind power, which is one of the promising renewable energies, has shown the high growth rate of 35 % of the annual average in the recent 5 years and also windmill related equipment market has been fast-growing. Yaw & Pitch bearing are the key parts of windmill and are machined by huge vertical lathe which is monopolized by the advanced countries. The purpose of this study is to develop the multi-tasking vertical lathe for 5 MW grade windmill bearings, which might be mass produced 3 or 5 years later. In this study, the structure of the crossrail and rotary table, which are the key units of the huge multi-tasking vertical lathe, were optimized through the finite element analysis. Also the basic performance of the rotary table has been evaluated.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.07a
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• pp.22-28
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• 2000

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.608-613
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• 1997

This study discusses the developmentof hydraulic rotary actuator design technology for industriol machinery and earthmoving equipment. The lubrication and wear analysis of sliding components of the machinery are very important parameters to sterngth the design technique. The analysis and were test are performed for the selected materials of the above mentioned coupled sliding members using the experimental results. One can selsct the better combination of sliding components.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.9-14
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• 2002

우리나라 농용 트랙터의 농가보급 율은 2000년 현재 13.9%로 약 19만대 정도이며 연간 약 2만대 정도의 농용 트랙터가 보급되고 있다 농작업 중 동력이 가장 크게 소요되는 경운 작업은 1차 쟁기작업과 2차 쇄토작업으로 크게 나눌 수 있는데, 근래에는 이것을 동시 작업 화하여 작업시간과 에너지 및 경비를 절감할 수 있는 로타리 경운 작업만 실시하는 경향으로 발전하고 있다. (중략)

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.21-26
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• 2002

우리나라의 농가 인구는 1990년에 666만명으로 전체인구의 15.5%를 차지하였으나 점차 줄어들어 2000년에는 8.7%에 지나지 않게 되었다. 또한 그 인구조차 노령화되어 현재 50세 이상인 농가인구의 비율이 49.1%에 이르는 실정이다. 농업의 대부분을 차지하는 논농사에서 가장 많은 노동력이 소요되는 작업으로는 경운 작업을 들 수 있다. 경운 작업은 플라우 경운과 로타리 경운으로 나눌 수 있는데 최근에는 로타리를 이용하는 경운으로 대체 되고 있는 현실이다. (중략)

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.635-642
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• 2014

The large volume multi-tasking vertical lathe was developed for machining the bearing parts for a wind power generator. Although the machined part is large in size high precision tolerances are required recently. One of the most important components to achieve this mission is the rotating table which holds and supports the part to be machined. The oil hydrostatic bearing is adopted for the thrust bearing and the rolling bearing for the radial bearing. In this article experimental performance evaluation and its analysis results are presented. The rotational accuracy of the table is assessed and the frequency domain analysis for the structural loop is performed. And in order to evaluate the structural characteristic of table the moment load experiment is performed. The rotational error motion is measured as below 10 ${\mu}m$ for the radial and axial direction and 22,800 Nm/arcsec of moment stiffness is achieved for the rotary table.

• Korean Journal of Agricultural Science
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• v.42 no.1
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• pp.53-61
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• 2015

Development of highly efficient and energy-saving tractors has been one of the issues in agricultural machinery. For design of such tractors, measurement and analysis of load on major power transmission parts of the tractors are the most important pre-requisite tasks. Objective of this study was to perform pre-processing procedures before effective analysis of load data of agricultural tractors (30, 75, and 82 kW) during major field operations such as plow tillage, rotary tillage, baling, bale wrapping, and to select the suitable pre-processing method for the analysis. A load measurement systems, equipped in the tractors, were consisted of strain-gauge, encoder, hydraulic pressure, and radar speed sensors to measure torque and rotational speed levels of transmission input shaft, PTO shaft, and driving axle shafts, pressure of the hydraulic inlet line, and travel speed, respectively. The entire sensor data were collected at a 200-Hz rate. Plow tillage, rotary tillage, baling, wrapping, and loader operations were selected as major field operations of agricultural tractors. Same or different farm works and driving levels were set differently for each of the load measuring experiment. Before load data analysis, pre-processing procedures such as outlier removal, low-pass filtering, and data division were performed. Data beyond the scope of the measuring range of the sensors and the operating range of the power transmission parts were removed. Considering engine and PTO rotational speeds, frequency components greater than 90, 60, and 60 Hz cut off frequencies were low-pass filtered for plow tillage, rotary tillage, and baler operations, respectively. Measured load data were divided into five parts: driving, working, implement up, implement down, and turning. Results of the study would provide useful information for load characteristics of tractors on major field operations.