• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.229-234
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• 2008

An AC-DC transfer standard(TS) is used for the AC voltage standard in the range of 2 mV to 1000 V below 1 MHz. Micro-potentiometer(${\mu}Pot$) is used to evaluate the ac-dc transfer difference(ADD) of the TS below 200 mV range. The ADD of the TS were changed by the loading effect caused from the input impedance change of the TS depend on frequency. An input impedance evaluation technique of the TS using ${\mu}Pot$ has been developed.

• Journal of Biosystems Engineering
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• v.14 no.2
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• pp.85-93
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• 1989

This study was intended to develop the system which controls header height of combine automatically by means of sensing the difference between the header and the ground surface. A micro-computer was used for the controller. The sensing unit designed for the study was composed of potentiometer, oscillating link, and gage wheel. An electric-hydraulic circuit was driven by microcomputer to control header height of combine. Performance of the control system was tested by computer simulation, stationary operation of header, and traveling on the simulated ground.

• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.123-130
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• 2010

A steering control system based on CAN(Controller Area Network) for autonomous tractor was developed to reduce duty of a central processing computer and to improve performance of steering control in terms of reduced control interval and error. The steering control system consisted of a SCU (Steering Control Unit), an EHPS system, and a potentiometer. The SCU consisted of an MCU (Micro Controller unit), an A/D converter, and a DC-DC converter, and a PID controller was used to control steering angle. The steering control system was communicated with the computer by CAN-bus. Each actuator and implement was connected to a multi-function board interfacing with the computer through a USB cable. Without CAN, control interval of the autonomous tractor was 1.5 seconds. When the CAN-based steering control system was combined with the autonomous tractor, however, control interval of the integrated system was reduced to those less than 0.05 seconds. When the autonomous tractor was operated with 1.5-s and 0.05-s control cycles at a 0.63-m/s travelling speed, the trajectories were close to straight lines for both of the control cycles. For a 1.34-m/s traveling speed, tractor trajectory was close to sine wave with a 1.5-s control cycle, but was straight line with a 0.05-s control cycle.