• Journal of Drive and Control
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• v.16 no.4
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• pp.1-8
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• 2019

The HPM (High-speed Power Matching) system is an electro-hydraulic control system. It directly controls the swash plate of the pump by selecting four-loop logic based on joystick signals, pump flow, and pressure signal to improve the efficiency and controllability of construction machines. In the NFC (Negative Flow Control) system, a typical pump control system using conventional open center type MCV, the loss is continuously generated by flow through the center bypass line even when the excavator is not in operation. Also, due to the slow response of the pump that indirectly controls the flow rate using the pressure regulator, peak pressure occurs at the start or stop of the operation. Conversely, the HPM system uses an MCV without center-by-pass flow path and the swash plate of a pump for the HPM is controlled by a high-speed proportional flow control valve. As a result, the HPM system minimizes energy loss in standby state of the excavator and enables peak pressure control through rapid electro-hydraulic control of a pump. In this paper, the concept of the HPM system algorithm is introduced and the hydraulic system efficiency is compared with the NFC system using the excavator SAT (System Analysis Tool).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.211-217
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• 2010

It is important to measure the mechanical properties of nanostructures because they are required to determine the lifetime and reliability of nanodevices developed for various fields. In this study, tensile tests for a multi-walled carbon nanotube (MWCNT) and a ZnO nanorod were performed in a scanning electron microscope (SEM). The force sensor was a cantilever type and was mounted in front of a nanomanipulator placed in the chamber. The nanomanipulator was controlled using a joystick and personal computer. The nanostructures dispersed on the cut area of a transmission electron microscope (TEM) grid were gripped with the force sensor by exposing an electron beam in the SEM; the tensile tests were the performed. The in situ tensile loads of the nanostructure were obtained. After the tensile test, the cross-sectional areas of the nanostructures were observed by TEM and SEM. Based on the TEM and SEM results, the elastic modulus of the MWCNT and ZnO nanorod were calculated to be 0.98 TPa and 55.85 GPa, respectively.

• Clean Technology
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• v.23 no.3
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• pp.248-255
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• 2017

In dismantling factories for recycling, it is important to input actual working data to a personal computer (PC) in order to monitor the work results and related recycling rate of the inputs. This should be performed with a keyboard, a mouse, or other devices. But when a worker is working in the factory, it could be bothersome or time consuming to go to the PC. Especially, workers who works at dismantling factories have a generally low education level are scared to use a PC, which could be used as a pretext for not using the PC. In some cases, data input is performed by a worker after the day's job. In this case, it could take additional time, the worker can make more mistakes, and the data could be unreliable. In this study, we developed a man-machine interface (MMI) device using a safety helmet. A joystick-like device, pushbuttons, and a radio frequency (RF) device for wireless communication is equipped in a safety helmet. This MMI device has functions similar to a PC mouse, and it has a long communication distance. RF is used because it consumes less battery power than Bluetooth. With this MMI device, workers need not go to a PC to input data or to control the PC, and they can control the PC from a long distance. The efficiency of PCs in a factory could be increased by using the developed MMI system, and workers at the dismantling factories could have less reluctance in using the PC.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.1
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• pp.17-27
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• 2012

This study provides development information on Omni-Wheel Drive Rider Robot, futuristic electric scooters, with autonomous driving systems that are used for people including the disabled and senior. Also, it is meaningful in suggesting alternatives to replace motorized wheelchairs or electric scooters for the future. Prior to development of Omni-Wheel Drive Rider Robot with autonomous driving systems, it surveyed 49 people, including 18 people who own electric scooters and 31 senior people who have not. The summary of the survey is as follows. First, inconveniences during riding and exiting and short mileage due and safety driving to problems of recharging batteries are the most urgent task. For these problems, the study shows that charging time of batteries, mileage, armrests, footrests, angle of a seat are the primary considerations. Second, drivers prefer joystick over steering wheels because of convenience in one-handed driving against dangers from footrest and carriageways sloping roads, paving blocks. One-handed driving can reduce driving fatigues with automatic stop systems. Moreover, the study suggests many design factors related to navigation systems, obstacle avoidance systems, omni-wheels, automatic cover-opening systems in rainy.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.32-44
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• 2015

In general, a series of ship steering motion is represented by the combination of translational motion and rotational motion of the ship. Especially, special-functioned ships such as large-scale cruises, ships for installing underwater optical cable, and diver ships must be able to reveal only a translational motion without the change of orientation. In this paper, a method to comprise an integrated control system based on the joystick as a command instrument for translational motion control is suggested. In order to realize the translational motion control system, several algorithms are suggested including the velocity command generation, the selection of motional variables, and the generation and tracking of reference inputs for the selected motional variables. A simulation bench is composed to execute simulations for several translational motion commands. At last, the effectiveness of the proposed method is verified by analyzing the simulation results.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.387-393
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• 2009

In this paper, a 3-D simulator was developed to estimate visually the performance of propelling and integrated control system of the underwater cleaning robot. Based on the dynamics analysis of the UCR, the 3-D model of the UCR was used in the simulator in which position and velocity are included Also, an input and control system using a joystick was developed, and the simulator was applied to the input and control of the simulator. Moreover, an integrated navigation control system was designed, and its performance was validated by a way-point simulator including a PI-based fuzzy control law.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.451-456
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• 2009

In this paper, a virtual force is generated and fed back to the operator to make the teleoperation more reliable, which reflects the relationship between a slave robot and an uncertain remote environment as a form of an impedance. In general, for the teleoperation, the teleoperated mobile robot takes pictures of the remote environment and sends the visual information back to the operator over the Internet. Because of the limitations of communication bandwidth and narrow view-angles of camera, it is not possible to watch certain regions, for examples, the shadow and curved areas. To overcome this problem, a virtual force is generated according to both the distance between the obstacle and the robot and the approaching velocity of the obstacle w.r.t the collision vector based on the ultrasonic sensor data. This virtual force is transferred back to the master (two degrees of freedom joystick) over the Internet to enable a human operator to estimate the position of obstacle at the remote site. By holding this master, in spite of limited visual information, the operator can feel the spatial sense against the remote environment. It is demonstrated by experiments that this collision vector based haptic reflection improves the performance of teleoperated mobile robot significantly.

• Journal of the Korean Society of School Health
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• v.6 no.1
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• pp.78-92
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• 1993

The purpose of this study is to find out the stress causes of the primary students in Korea, through the three major methods, life event score, multiple regression about stress causes and G.H.Q. path-diagram. A survey was made of 889 students who were selected among students of six primary schools in seoul and Ka-pyeng, from Sep. 28 to Oct. 2. 1992. The results of this study are summarized as follows : 1. Life event score Among the children's life events, (deaths of family) (degrade of school record) (the increase of absence days) (divorce of parents) (trouble with relationship) are high ranking in life event score. Besides, (scolded by teacher and parents) (beginning of extracurricular work) are spread stress causes. In conclusion, these stress causes are shown by two aspects, home, school, and so children are under stress circumstance in both places. These stress causes vary with area and sex. 2. Multiple regression about stress causes and G.H.Q. This study analysed how a stress caused by home life affects the children's health of mind and body. The most influential factors are , and these factors vary with area and sex. 3. Path-diagram This study proved that socio-psychological school environment raises children to secede from school, and this secession that operates as a stress cause affects children's health of mind and body. This serial process is analysed by path analysis, and made out a path-diagram. In conclusion, as expected socio-psychological,school environment affects the children's health of mind and body. This is shown by two aspects : positive, negative. This stress causes vary with area and sex.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.117-124
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• 1989

The intelligent trajectory control method that controls moving direction and average velocity for a prosthetic arm is proposed by pattern recognition and force estimations using EMG signals. Also, we propose the real time trajectory planning method which generates continuous accelleration paths using 3 stage linear filters to minimize the impact to human body induced by arm motions and to reduce the muscle fatigue. We use combination of MLP and fuzzy filter for pattern recognition to estimate the direction of a muscle and Hogan`s method for the force estimation. EMG signals are acquired by using a amputation simulator and 2 dimensional joystick motion. The simulation results of proposed prosthetic arm control system using the EMf signals show that the arm is effectively followed the desired trajectory depended on estimated force and direction of muscle movements.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.585-589
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• 2016

Recently, the robotic assist system for cardiovascular intervention gets continuously growing interest. The robotic cardiovascular intervention systems are largely two folds, systems for cardiac ablation procedure assist and systems for vascular intervention assist. For the systems, the clinician controls the catheter inserted through blood vessel to the heart via a master console or master manipulator. Most of the current master manipulators have structure of joystick-like pivoting 2 degree of freedom (DOF) handle in the core, which is used in parallel with other sliding switches and input devices. It however is desirable to have customized and optimized design manipulator that can provide clinician with intuitive control of the catheter motion fully utilizing the advantage of the use of robotic structure. A 6 DOF kinematic mechanism that can capture the motion control intention of the clinician in translational 3 DOF and rotational 3 DOF is proposed in this paper. Also, a master-slave motion relationship specially designed for the cardiac catheter manipulation motion is proposed and implemented in an experimental prototype. Design revision for implementation of more efficient motion and experiment in combination with an experimental slave robot system for catheter manipulation are underway.