• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.51-58
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• 2005

The development of the high-efficiency machine-tools equipment and new cutting tool materials with high hardness, heat- and wear-resistance has opened the way to application of high-speed cutting process. The basic argument of using of high-speed cutting processes is the reduction of time and the respective increase of machining productivity. In this sense, the spindle units may be regarded as one of the most important units, directly affecting many parameters of high-speed machining efficiency. One of the possible types of spindle units for high-speed cutting is the air-bearing type. In this paper, we propose the mathematical model of the dynamic behavior of the air-bearing spindle. To provide the high-level of speed capacity and spindle rotation accuracy we need the adequate model of "spindle-bearings" system. This model should consider characteristics of the interactions between system components and environment. To find the working characteristics of spindle unit we should derive the equations of spindle axis movement under the affecting factors, and solve these equations together with equations which describe the behavior of lubricant layer in bearing (bearing stiffness equations). In this paper, the three influence coefficients are introduced, which describe the center of spindle mass displacement, angle of shaft rotation around the axes under the unit force application and that under the unit torque application. These coefficients are operated in the system of differential equations, which describes the spindle axis spatial movement. This system is solved by Runge-Kutta method. Obtained trajectories and amplitude-frequency characteristics were then compared to experimental ones. The analysis shows good agreement between theoretical and experimental results, which confirms that the proposed model of air-bearing spindle is correctis correct

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1112-1118
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• 1990

The end tip position control of a flexible robot arm has been presented by utilizing the feedback signal from the rate-gyro mounted at the end tip. Kalmann filter and the state feedback gains were determined by optimal sense based upon the parameter from the geometrical and electrical data of the flexible arm system. The simulation and experiment were performed and it has been proved that implementation of the rate-gyro drastically improves the performance.

• Smart Structures and Systems
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• v.15 no.4
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• pp.931-947
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• 2015

This paper focuses on the design of an intelligent control system. The used techniques are based on Neuro Fuzzy approaches applied to a magnetorheological damper in order to reduce the vibrations over footbridges; it has been applied to the Science Museum Footbridge of Valladolid, particularly. A model of the footbridge and of the damper has been built using different simulation tools, and a successful comparison with the real footbridge and the real damper has been carried out. This simulated model has allowed the reproduction of the behaviour of the footbridge and damper when a pedestrian walks across the footbridge. Once it is determined that the simulation results are similar to real data, the control system is introduced into the model. In this sense, different strategies based on Neuro Fuzzy systems have been studied. In fact, an ANFIS (Artificial Neuro Fuzzy Inference System) method has also been used, in addition to an alternative Neuro Fuzzy approach. Several trials have been carried out, using both techniques, obtaining satisfactory results after using these techniques.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.1039-1046
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• 2009

In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. By using modal analysis, the system model is reduced to guarantee the detectability which is a necessity for the static output feedback control design. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.

• The Journal of Korean Institute for Practical Engineering Education
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• v.5 no.1
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• pp.34-39
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• 2013

This paper suggests an input device that allows a user not only to naturally interact with education contents in virtual environment but also to sense haptic feedback according to his/her interaction. The proposed system measures a user's motion and then creates haptic feedback based on the measured position. To create haptic information in response to a user's interaction with educational contents in virtual environment, we develop a motion input device which consists of a motion controller, a haptic actuator, a wireless communication module, and a motion sensor. To measure a user's motion input, an accelerometer is used as the motion sensor. The experiment shows that the proposed system creates continuous haptic sensation without any jerky motion or vibration.

• Journal of KSNVE
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• v.8 no.5
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• pp.841-848
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• 1998

In the gear manufacturing, tooth modification is usually applied for the prevention of tooth impact during the loading. In contrary, tooth profile error causes amplifying the whine noise which is cumbersome to reduce in the automobile gear box. So optimum quantity of the modifications must be obtained for the good performance in the vibrational sense. In this paper, a formulation to define the tooth curve by considering the profile manufacturing error and loading deformation of the gear tooth is suggested and the transmission error and loading deformation of the gear tooth is suggested and the transmission error with modified tooth in the gear system is evaluated. A pair of gear set is mathematically modelled. The equivalent excitation in the gear vibratonal model is formulated. For the experimental evaluaton on the derived transmission error function, a simple geared system is set up in which the gears are designed to give pre-designed tooth profile modification and manufactured by CNC Wire Cutting Machine. Under slow speed operaton, the transmission error of the gear pair is measured by using two rotational laser vibrometers, compared with the calculated one of which the result shows good agreement.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.225-232
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• 2007

A tooth profile modification for loaded gears is used to avoid a tooth impact. Since a tooth profile error causes amplification of the cumbersome whine noise in automotive gear transmissions, an optimal quantity of tooth profile modifications must be obtained for good performance in the vibration sense. In this paper, a tooth profile modification curve considering profile manufacturing errors and elastic deformation of the gear tooth is formulated; in addition, transmission errors of the gear system with modified teeth are verified. The equivalent excitation due to transmission errors is formulated. For experimental evaluation of the transmission error, the transmission error for a simple gear system was measured by two rotational laser vibrometers. Finally, we perform a comparative analysis between the calculated and measured responses to the excitations due to the transmission error to verify the practicability of the application to automotive transmissions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.1-7
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• 2019

A chatter lobe analysis is frequently used to look at the chatter state. Even if there is a lot of research on chatter, chatter lobe characteristics are not well defined. In this study, the chatter lobe behavior according to several variables of vibration mode is verified for further clarity. The dynamic variables of the chatter model are defined and their behaviors on chatter lobe boundary are analyzed in detail. In this sense, the chatter model with 2-DOF (2-DOF) was used to analyze chatter stability characteristics. The discussed results are satisfying and these can be used for the prediction of chatter existence in machining processes of 2-DOF systems in several revolution range. These analyses indicate a better agreement for predicting an appropriate stability lobe over a wide detailed range of critical depths of cut in machining operation. The results allow an excellent prediction of chatter according to various static and dynamic variables in machining states. The behavior of chatter dynamic variables in machining were also discussed in detail. All these results can also be applied to other machining processes by establishing a chatter model in a 2-DOF system.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.1
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• pp.1-7
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• 2014

In this study, the effect of the automotive haptic-seat technology which can transmit the driving information by the vibro-stimulus from the seat was investigated to overcome previous system's limitation relied on the visual and audial method and to help handicap driving. A prototype haptic seat covers with 30 coin-type motors and driver module were developed for this sake. A driving simulator on the 6-DOF motion-base was used for driving situation and we executed the seat vibro-stimulus test with 10 young participants who have normal tactile sense. The haptic recognition ratio by 30 locations was measured and analyzed in the result. The intensity of vibro-stimulus was adjusted by input voltage of motors (1.5V,2.5V,3.5V). All vibro-stimulus locations at 2.5V and 3.5V could be recognized by all participants and even in the lowest recognition ratio of 1.5V. The results showed that the seat vibration stimulus could be useful to transfer the drivers' information while driving.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.191-200
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• 2021

Purpose : Chronic ankle instability can lead to problems in balance and gait due to weakness of the ankle muscles and decreased proprioceptive sensation. Balance training that stimulates proprioceptors is necessary to improve ankle stability. We aimed to compare the effects of unstable support balance exercises using whole body sonic vibration and an aero-step (TOGU) on proprioception and balance in individuals with unilateral functional ankle instability. Methods : Thirty-six participants with unilateral functional ankle instability were randomly recruited and divided into two groups (group 1 = sonic whole body vibration, group 2= TOGU). Individuals in each group participated in training for 5 weeks, 40 minutes per session, 5 times per week, and performed weight-bearing exercises in five postures on different unstable support surfaces. Proprioception was measured by digital inclinometer (Dualer IQ), and balance was measured by force platform (Biodex balance system). Results : Significant differences were observed in proprioception before and after intervention within both group (p<.05). Significant differences were also observed in the balance index before and after intervention within both groups (p<.05). Conclusion : As a result of this study, it is suggested that for individuals with ankle instability, unstable support surface training using a whole body sonic vibrator and TOGU can have a positive effects on proprioception and balance ability.