• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.421-426
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• 2015

Need to develop human body's posture supervised robots, gave the push to researchers to think over dexterous design of exoskeleton robots. It requires to develop quantitative techniques to assess human motor function and generate the command to assist in compliance with complex human motion. Upper limb rehabilitation robots, are one of those robots. These robots are used for the rehabilitation of patients having movement disorder due to spinal or brain injuries. One aspect that must be fulfilled by these robots, is to cope with uncertainties due to different patients, without significantly degrading the performance. In this paper, we propose chattering free sliding mode control technique for this purpose. This control technique is not only able to handle matched uncertainties due to different patients but also for unmatched as well. Using this technique, patients feel active assistance as they deviate from the desired trajectory. Proposed methodology is implemented on seven degrees of freedom (DOF) upper limb rehabilitation robot. In this robot, shoulder and elbow joints are powered by electric motors while rest of the joints are kept passive. Due to these active joints, robot is able to move in sagittal plane only while abduction and adduction motion in shoulder joint is kept passive. Exoskeleton performance is evaluated experimentally by a neurologically intact subjects while varying the mass properties. Results show effectiveness of proposed control methodology for the given scenario even having 20 % uncertain parameters in system modeling.

• Journal of Auto-vehicle Safety Association
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• v.5 no.2
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• pp.24-31
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• 2013

This paper describes a coordinated control algorithm for rear-side collision avoidance. In order to assist driver actively and increase driver's safety, the proposed coordinated control algorithm is designed to combine lateral control using a steering torque overlay by Motor Driven Power Steering (MDPS) and differential braking by Vehicle Stability Control (VSC). The main objective of a combined control strategy is twofold. The one is to prevent the collision between the subject vehicle and approaching vehicle in the adjacent lanes. The other is to limit actuator's control inputs and vehicle dynamics to safe values for the assurance of the driver's comfort. In order to achieve these goals, the Lyapunov theory and LMI optimization methods has been employed. The proposed coordinated control algorithm for rear-side collision avoidance has been evaluated via simulation using CarSim and MATLAB/Simulink.

• Journal of IKEEE
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• v.24 no.1
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• pp.147-153
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• 2020

Conventional lane detection algorithms have problems in that the detection rate is lowered in road environments having a large change in curvature and illumination. The probabilistic Hough transform method has low lane detection rate since it exploits edges and restrictive angles. On the other hand, the method using a sliding window can detect a curved lane as the lane is detected by dividing the image into windows. However, the detection rate of this method is affected by road slopes because it uses affine transformation. In order to detect lanes robustly and avoid obstacles, we propose driving assist system using semantic segmentation based on deep learning. The architecture for segmentation is SegNet based on VGG-16. The semantic image segmentation feature can be used to calculate safety space and predict collisions so that we control a vehicle using adaptive-MPC to avoid objects and keep lanes. Simulation results with CARLA show that the proposed algorithm detects lanes robustly and avoids unknown obstacles in front of vehicle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1205-1211
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• 2011

In this paper, we developed a pacemaker that can increase the efficacy of a left ventricular assist device (LVAD) and increase the survival rate for patients suffering end-stage heart failure. Because LVAD patients can experience arrhythmia, the pacemaker incorporated into the LVAD has the important role of sustaining sufficient blood circulation during arrhythmia. The electrode of the pacemaker is located at the apex of the left ventricle, where the VAD's inlet cannula is connected. This is efficient placement, in that the electrode can transmit electrical stimulation directly to the Purkinje fibers of the myocardium. The pacemaker can change the stimulation rate from 0 bpm to 191.4 bpm when a button is pressed on the external control module, and the pacemaker normally stimulates the heart at 60 bpm with 0.25 J of energy. We performed animal experiments to evaluate the performance and reliability of the combination of the LVAD and pacemaker. At pacemaker stimulation rates of 86.4 bpm, 100.2 bpm, 126.6 bpm, we recorded the ECGs, aortic pressures, and flow rates to analyze the heart loads.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.771-782
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• 2017

This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4595-4603
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• 2015

The purpose of this study was to examine the effects of a mentoring program designed to assist nursing students adjust to life in college and strengthen their leadership abilities. The mentoring program consisted of nine sessions including information on basic mentorship functions, as well as the results of similar previous studies. This was a quasi-experimental study with a non-equivalent control group pre-post test design in order to evaluate the results of this program. Mentoring and data collection were performed from March 3 to May 30, 2014. The experimental group participants included 20 mentee students (in grades 1 and 2), and 20 mentors (in grades 3 and 4). Both pre and post tests were administered before and after the mentoring program. The score for "adjust to life in college" was more significantly increased in the mentee student experimental group as compared with the control group. Similarly, the post test score for "leadership" was more significantly increased from the pre test score in the mentor student experimental group. However, no statistically significant differences were found for the post-pre test "leadership" score between the mentor student experimental group and the control group. These results suggested that mentoring had a significant effect on the ability of nursing students to adjust to life in college, as well as to strengthen their leadership abilities, and the program needs more developed contents for leadership.

• Journal of Drive and Control
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• v.17 no.1
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• pp.37-43
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• 2020

An intelligent excavator can be divided into Machine Guidance (MG), semi-automatic, and unmanned by technology. The MG technology excavator is equipped with a tilt sensor on each link of the excavator and a GPS is installed on the excavator body to inform the user of the position of the excavator bucket end. Machine control (MC) technology that assists the user's work can be divided into semi-automatic and fully automatic technology. The semi-automatic MC equipment has already been commercialized by Komatsu and Caterpillar. The MC excavator is equipped with an electro-hydraulic system, sensors and controllers to control the excavator bucket end according to the user's needs. In this study, the semi-automated excavator modified based on manual excavator, is equipped with an electro-hydraulic system, a controller system, multi-sensors and a control algorithm is developed to assist in excavation work such as leveling and grading. By applying the developed technology, it was possible to confirm productivity improvement compared to manual digging and leveling work. In the future, further research to improve the accuracy of the hydraulic precision control and collaborative work with heterogeneous construction equipment such as dump truck and automated collaboration tasks technology could be developed.

• Smart Structures and Systems
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• v.21 no.3
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• pp.359-371
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• 2018

Strong seismic events commonly cause large drift and deformation, and functionality failures in the superstructures. One way to prevent functionality failures is to design structures which are ductile and flexible through yielding when subjected to strong ground excitations. By developing forces that assist motion as "negative stiffness forces", yielding can be achieved. In this paper, we adopt the weakening and damping method to achieve a new approach to reduce all of the structural responses by further adjusting damping phase. A semi-active control system is adopted to perform the experiments. In this adaptation, negative stiffness forces through certain devices are used in weakening phase to reduce structural strength. Magneto-rheological (MR) dampers are then added to preserve stability of the structure. To adjust the voltage in MR dampers, an inverse model is employed in the control system to command MR dampers and generate the desired control forces, where a velocity control algorithm produces initial required control force. An extensive numerical study is conducted to evaluate proposed methodology by using the smart base-isolated benchmark building. Totally, nine control systems are examined to study proposed strategy. Based on the numerical results of seven earthquakes, the use of proposed strategy not only reduces base displacements, base accelerations and base shear but also leads to reduction of accelerations and inter story drifts of the superstructure. Numerical results shows that the usage of inverse model produces the desired regulated damping, thus improving the stability of the structure.

• Toxicological Research
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• v.28 no.3
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• pp.143-149
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• 2012

To prepare measures for practical policy utilization and the control of heavy metals, hazard control related institutions by country, present states of control by country, and present states of control by heavy metals were examined. Hazard control cases by heavy metals in various countries were compared and analyzed. In certain countries (e.g., the U.S., the U.K., and Japan), hazardous substances found in foods (e.g., arsenic, lead, cadmium, and mercury) are controlled. In addition, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) recommends calculating the provisional tolerable weekly intake (PTWI) of individual heavy metals instead of the acceptable daily intake (ADI) to compare their pollution levels considering their toxicity accumulated in the human body. In Korea, exposure assessments have been conducted, and in other countries, hazardous substances are controlled by various governing bodies. As such, in Korea and other countries, diverse food heavy metal monitoring and human body exposure assessments are conducted, and reducing measures are prepared accordingly. To reduce the danger of hazardous substances, many countries provide leaflets and guidelines, develop hazardous heavy metal intake recommendations, and take necessary actions. Hazard control case analyses can assist in securing consumer safety by establishing systematic and reliable hazard control methods.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.152-159
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• 2004

The Grid system is an emerging computing infrastructure that will substitute for existing distributed systems. However end users have a difficulty in using the Grid because of its complicated usage, which is an inherent characteristic from the heterogeneous mechanism of the Grid. In this paper, we present the JCML(Job Control Markup Language) and its GUI-based editor, which not only provide users with ease of use, improved working environment, but assist users to execute their jobs efficiently The JCML is a job control language that improves the RSL of Globus, which defines global services in Grid. The JCML is designed to support flexibility among various Grid services using standard XML. And it makes use of a graph representation method, GXL(Graph eXchange Language), to specify detailed job properties and dependencies among jobs using nodes and edges. The JCML editor provides users with GUI-based interface. With the JCML editor, a complicated job order can be easily completed using very simple manipulations with a mouse, such as a drag-and-drop.