• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.53-56
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• 2004

Recently the interferometric synthetic aperture radiometer with sub-Y-type antenna array was suggested to improve the spatial resolution than that of conventional Y-type with the same number of antenna elements. The sub-Y-type performance has been reported under a point source target. In this paper, the performance of sub-Y-type is evaluated under contiguous objects. The angular resolution of sub-Y-type with 52 antennas was compared with that of Y-type with the 40 antennas. The images of sub-Y -type and Y-type array were simulated under the contiguous objects. The sub-Y-type showed higher resolution than Y-type in the simulation and experiments. The sub-Y-type has high spatial resolution than Y-type in case of contiguous source as well as single point source.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.577-580
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• 2004

To overcome with large size noise source distribution network design difficulty in interferometric radiometer system, especially for sub-Y-type array, a new on-board calibration technique using noise re-radiation is proposed in this paper. The suggested calibration technique is using noise re-radiation effect of center antenna after noise source injection from matched load. This approach is especially proper to sub-Y-type array interferometric synthetic aperture radiometer in mm-wave frequency band. Compared with noise injection network of a conventional synthetic aperture radiometer, the system mass, volume, and hardware complexity is reduced and cost-effective. Only one internal noise source, matched load, is used for injection using noise re-radiation technique a small set of sub-Y receiver channels is calibrated. Detailed calibration scenario is discussed and simulation results about noise re­radiation effect are presented.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.887-891
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• 2013

Human rights at poor working condition is the severe problem in modern manufacturing system. The industrial dual-arm robot is being developed to meet these social issues fundamentally. The dual-arm robot can work instead of human workers. We developed the new dual-arm robot for manufacturing mobile phone and TV. It has advantages such as the solo controller for both arms, the human sized body and arms. The software platform for the industrial dual-arm robot is being developed which has strength in its convenience and intelligence compared to conventional the robot software platforms. Here the development of the dual-arm robot software platform is introduced.

• Journal of Industrial Technology
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• v.40 no.1
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• pp.19-23
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• 2020

In this paper, we proposed a PC-based CNC control system using EtherCAT-based servo drive and I/O device. The default communication of LinuxCNC is a parallel port, and data processing with high bandwidth is impossible. However, it is possible to apply various bandwidth devices through the application of EtherCAT, one of the industrial Ethernet communications with high bandwidth. Therefore, the hardware control method of LinuxCNC was applied through EtherCAT communication from the existing parallel port. Finally, through HAL configuration, I/O device operation check and 3-axis motion control proved the LinuxCNC system with EtherCAT.

• Journal of Aerospace System Engineering
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• v.14 no.2
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• pp.36-43
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• 2020

Many countries and international organizations have carried out rover missions to explore planetary surfaces. Accordingly, the demand for mechatronics education, which is closely related to building exploratory robots, is also steadily increasing. However, due to the complexity in understanding the background information needed for mechatronics, it is hard for pre-college students to study such process. In this study, we suggest an educational platform for mechatronics using a combined robot kit with a spherical robot and a smartphone application. To provide a visual understanding, the dynamic model of the robot is constructed while analyzing the error between actual driving and a simulation, and the educational algorithm of the game and a feedback method are proposed to improve the learning efficacy by considering the user's level of knowledge of mechatronics. We use this educational spherical robot to develop a curling game platform that can impart engineering education even when students lack significant knowledge.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.359-362
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• 2006

This study develops an automatic berthing control algorithm for ships with a bow thruster and a stern thruster as well as a rudder. A nonlinear mathematical model for low speed maneuvering of ships is used to develop a MIMO(multi-input multi-output) nonlinear control algorithm. The algorithm consists of two parts, which are forward velocity control and heading angle control. The control algorithm is designed based on the longitudinal and yaw dynamic models of ships. The desired heading angle is obtained by the so called "Line of Sight" method. An optimal control force allocation method of the rudder and the thrusters is suggested. The nonlinear control algorithms are tested by numerical simulations using MATLAB, and shows good tracking performances.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.369-371
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• 1999

A torque ripple minimization technique is proposed for high power induction motors driven by 3-level inverters with switching frequency of inverter switching elements limited around 500Hz level. It is noted that conventional DTC algorithms with torque ripple minimization scheme are devised for applications with relatively high switching frequency above 2-3kHz. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation results show effectiveness of the proposed control algorithm, and associated experimental works will be presented in the final paper.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.381-383
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• 1999

In this paper a remote monitoring and control system using SNMP(Simple Network Management Protocol) for UPS (Uninterruptible Power Supply) systems is proposed. The local remote system by RS-232 or RS-485 communication code or the wide remote system by modems is used for conventional remote monitoring & control system for UPSs. But recently because of communication cost and long distance the system is changed to remote control systems through internet and information communication network. And serial communication method by RS-232 or RS-485 is used between agent and UPSs. In this study. we designed and developed the system which is able to control UPSs and to monitor errors. statuses and actual values transmitted from UPS through internet.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.492-497
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• 2016

Teaching an industrial robot is still a dangerous and time-consuming process. It is expected that a robot can track a trajectory that is repeatedly taught by a human operator. Teaching a robot in joint space is easier than that in Cartesian space or a work space because the robot will never lose its stability when it is taught and operated in a joint space. However, it is very easy for a robot to lose its stability when it is taught in a work space. This is because of the singular points problem in kinematics for manipulators. Thus, experts should teach a given task to a robot in a careful manner. A new algorithm that avoids the problem of singular points is proposed. Using this proposed method, a user can freely teach a robot without the chance of instability in an entire work space.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.511-516
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• 2016

Guaranteeing the safety of human workers around robots has become an important issue with the increasing demand for human-robot collaboration in industrial production lines. This study proposes a robot manipulator equipped with a counterbalancing mechanism that reduces the power of actuators required to drive the robot, thus keeping a human worker safer in a human-robot collaborative environment. A counterbalancing torque that exactly cancels out the gravitational torque in the proposed mechanism is generated by restoring the force of a spring in the counterbalancing mechanism. A prototype design and experimental results are presented to verify the effectiveness of the proposed method.