• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.518-522
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• 2001

The main problem of the calibration of robots is to measure the position and orientation of a robot end effector. The calibration methods can be used as tool to improve the accuracy of robots without change of the arm or control architecture or robots. But such calibration methods require accurate measurements. Dynamic measurement of position and orientation provides a solution for this problem and improves dynamic accuracy by dynamic calibration of robots. This paper describes the development of the laser tracking system capable of determining the static and dynamic performance of industrial robots. The structure and systems components are presented and basic experimental results are included to demonstrated the instrument performance. The system can be applied to the remote controlled mobile robots as well s the calibration of robots.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.532-539
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• 2001

In robot teleoperation, much research has been carried out to control the slave robot from remote site. One of the essential devices for robot teleoperation is the masterarm, which is a path command generating device worn on human arm. In this paper, a new masterarm based on human kinematics is proposed. Its controller is based on the distributed controller architecture composed of two controller parts: a host controller and a set of satellite controllers. Each satellite controller measures the corresponding joint angle, while the host controller performs forward and inverse kinematics calculation. This distributed controller architecture can make the data updating faster, which allows to implement real-time implementation. The host controller and the satellited controllers are networked via three-wire daisy-chained SPI(Serial Peripheral Interface) protocol, so this architecture makes the electrical wiring very simple, and enhances maintenance. Analytical method for finding three additional unknown joint angles is derived using only three measured angles for each shoulder and wrist, which makes th hardware implementation very simple by minimizing the required number of satellite controllers. Finally, the simulation and experiment results are given to demonstrate the usefulness and performance of the proposed masterarm.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.1-6
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• 2012

Purpose : This study is to investigate the modulatory effects to the ultraviolet induced erythema of pain processing system. Methods : Thirty six healthy volunteers were divided into none treatment group (n=6), indomethacine group (n=6), subsensory level electrical stimulation group (n=6), sensory level electrical stimulation group (n=6), motor level electrical stimulation group (n=6), noxious level electrical stimulation group (n=6). Subjects were induced erythema for three times minimal erythema dose (MED) at upper arm of dermatome C6 level. Each experimental group had mechanical pain threshold (MPT), electrical pain threshold (EPT), thermal pain threshold (TPT). Results : This study revealed that we observed that pain thresholds were significantly correlated with each other in pain processing system. The effect of electrical stimulation levels evaluates were shown to be significant differences pain control effect in electrical stimulation group (sensory, motor level electrical stimulation groups) more than indomethacine group, subsensory level and control group. Conclusion : In this study, it was found that the effect of ultraviolet induced erythema of pain control by modulatory electrical stimulation.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1725-1734
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• 2016

This paper presents a novel seven-level (7L) voltage source converter for high-power medium-voltage applications. The proposed topology is an H-bridge connection of two nested neutral-point clamped (NNPC) converters and is referred to as an HNNPC converter. This converter exhibits advantageous features, such as operating over a wide range of output voltages, particularly for 10-15 kV applications, without the need to connect power semiconductors in series; high-quality output voltage; and fewer components relative to other classic seven-level topologies. A novel sinusoidal pulse width modulation technique is also developed for the proposed 7L-HNNPC converter to control flying capacitor voltages. One of the main features of the control strategy is the independent application of control to each arm of the converter to significantly reduce the complexity of the controller. The performance of the proposed converter is studied under different operating conditions via MATLAB/Simulink simulation, and its feasibility is evaluated experimentally on a scaled-down prototype converter.

• Journal of Korean Physical Therapy Science
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• v.19 no.4
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• pp.1-6
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• 2012

Purpose : The current research examines the muscle activity that happens during scaling practice subject to 20 dental hygienic students with musculoskeletal pain and then propose a basic data according to the working attitude of the Dental Hygienist. Method : The Nordic-style questionnaire is used to define experimental group with musculoskeletal pain and control group. During the scaling the surface EMG device is used to measure the muscle activity of experimental and control group. Study design : The surface EMG is measure RMS(root mean square) of suboccipital muscle, biceps brachii, upper trapezius, and brachioradialis muscle activity. Results : In the experimental group, the RMS of upper trapezius and brachioradialis is increased during scaling practice(p<0.05), but the control group's RMS is not changed(p>0.05). Conclusion : Musculoskeletal pain may contribute to increase muscle activity of neck & arm during scaling practice. In the future we think there is a need to raise the office efficiency by subjecting to dental hyginiest that are in the clinics and performing experiments.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.451-462
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• 2016

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.176-183
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• 2009

This paper proposes command signal generating method for a wearable robot using the force as the input signal. The basic concept of this system pursues the combination of the natural and sophisticated intelligence of human with the powerful motion capability of the robot. We define a task for the command signal generation to operate with the human body simultaneously, paying attention to comfort and ease of wear. In this study, we suggest a basic exoskeleton experimental system to evaluate a HRI(Human Robot Interface), selecting interfaces of arm braces on both wrists and a weight harness on the torso to connect the robot and human. We develop the HRI to provide a command for the robot motion. It connects between the human and the robot with the multi-axis load-cell, and it measures the relative force between the human and the robot. The control system calculates the trajectory of end-effector using this force signal. In this paper, we verify the performance of proposed system through the motion of elbow E/F(Extension/Flexion), the shoulder E/F and the shoulder Ab/Ad (Abduction/Adduction).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1015-1018
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• 2005

This study intended to demonstrate a general system as an web server implemented by pure software solution and focused on collecting data by remote control through Internet and constructing its' control frame. To achieve these, this study suggested an optimized, low-power, ultra tiny embedded web server. When unpredictable accidents, such as heat sensor or industrial disasters, happen, it will connect sensors collecting building information each other by network and obtain final results via web porting, web hardware control or porting, or hardware test process in a boot loader on the basis of StrongARM SA-1110 processor.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1659-1669
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• 2018

An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.44-51
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• 2011

In this paper, an easy-to-use measurement device for illumination distribution is developed. The device consists of a sensor array module, a control module, and a PC interface. The sensor array module incorporates CIE 1931 color sensors and the ARM-based 96 MHz microcontroller in the control module for measurement and data processing. The sensor array module contains 64 color sensors arranged in a $16{\times}4$ array. The sensitivity of the sensor array module can be adjusted depending on the illumination level to be measured. The measurement data and control signals are exchanged via USB 2.0 standard. To demonstrate the performance of the device, the illumination distribution is measured for colors of red, green, and blue and is graphically shown. The device can be used for measurement of the illumination distribution, design and adjustment of LED illumination.