• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.654-661
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• 2015

Stairs are the most popular obstacles in buildings and factories. To enlarge the application areas of a field robotic platform, stair-climbing is very important mission. One important reason why a stair-climbing is difficult is that stairs are various in sizes. To achieve autonomous climbing of various-sized stairs, dynamic modeling is essential. In this research, an inverse dynamic modeling is performed to enable an autonomous stair climbing. Stair-climbing robotic platform with flip locomotion, named FilpBot, is analyzed. The FlipBot platform has advantages of robust stair-climbing of various sizes with constant speed, but the autonomous operation is not yet capable. Based on external constraints and the postures of the robot, inverse dynamic models are derived. The models are switched by the constraints and postures to analyze the continuous motion during stair-climbing. The constraints are changed according to the stair size, therefore the analysis results are different each other. The results of the inverse dynamic modeling are going to be used in motor design and autonomous control of the robotic platform.

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.48-54
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• 1999

For the high speed linear motor and the transportation device at clean room, a magnetic levitation rail without contact using the repulsive force of permanent magnets was newly developed. The characteristics of repulsive and lateral forces of the magnetic levitating system using permanent magnet was studied and the devised magnetic levitating system was evaluated by analytical and experimental approaches. This system is composed of two fixed guide rails with the rare earth permanent magnet array and a moving unit which is attached two magnet pairs at each sides. Because this system was forcedly levitated by the face to face repulsive forces, levitating air gap length can be repulsive force of an auxiliary magnetic repulsion system on the center of moving unit.

• Korean Parent-Child Health Journal
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• v.10 no.1
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• pp.77-90
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• 2007

Purpose: Motor vehicle crashes are the leading cause of death among children younger than 14 years old. The purposes of this study were to 1) provide a basic overview of child safety seats, 2) review car seat safety usage and misuse, 3) suggest interventions to motivate the usage of child safety seats. Method: The design was a descriptive study with literature review. Previous studies were searched of PUBMED, ProQuest and KERIS. Result: Child safety seats and automobile safety belts protect children in a crash if they are used correctly, but if a child does not fit in the restraint correctly, it can lead to injury. A child safety seat should be used until the child correctly fits into an adult seat belt. Conclusion: To improve child passenger's safety, educational, legislational and environmental enforcements are needed: educational interventions to promote use of child safety seats, strengtened legislation to mandate use of child safety seats, establishment of public acquirements.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.224-235
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• 2017

Purpose: Reliability is the most important factor to detect defects as wind turbines are deployed in large blades. The methods of detecting defects are various, such as non-destructive inspection and thermal imaging inspection. We propose the phased array ultrasonic testing method of non-destructive testing. Methods: We propose the active pressure mechanism for wind power blade. The phase array ultrasonic inspection method is used for fault detection inner blade surface. Controlled pressure of mechanism with respect to z-axis is important for guarantee the result of phase array ultrasonic inspection. The model based control and proposed mechanism are utilized for overall system stability and effectiveness of system. Result: The result of proposed pressure mechanism B is more stable than A. Convergence speed is also faster than A. Conclusion: We confirmed the performance of the proposed constant pressure mechanism through experiments. Non-destructive testing was applied to the specimen to confirm the reliability of detecting defects.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.6
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• pp.317-323
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• 2013

A multi-perforated tube indicates the existence of multiple holes of various shapes on the surface of a long cylinder-type or rectangular tube, and a hole installed on the surface is called an orifice, as it is relatively small in size, compared with the surface area of the tube. In this study, the flow characteristics of a circular multi-perforated tube with many orifices on the surface were investigated experimentally and numerically. The volume flowrate issuing from each orifice, discharge angle, effective flow area ratio, and the flow fields around the orifices were measured and visualized, with the variation of the orifice area ratio, at the same blockage ratio. The volume flowrate distributions along the flow direction of the multi-perforated tube tends to be more uniform, as larger orifices were positioned at the inlet side of the multi-perforated tube, compared with no orifice area change along the flow direction.

• Physical Therapy Rehabilitation Science
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• v.2 no.1
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• pp.1-6
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• 2013

Objective: The aim of this review is to explore the latest intervention trends and effects of EMG-triggered functional electrical stimulation on the upper extremity functions in stroke patients. Design: Systematic review on clinical trials. Methods: A systematic literature search was performed to identify clinical trials evaluating the effects of EMG-triggered functional electrical stimulation (EMG-FES) and task-oriented EMG-triggered FES on the hand functions in stroke patients. Literature review was conducted with the following key words: hand function, functional electrical stimulation, task-oriented, stroke. Results: Ten clinical trials were included; 8 of them were randomized controlled trial, 1 was block-randomized, and 1 was a pre-post comparison study. A positive effect of electrical stimulation was reported in the patient groups that were treated with functional electrical stimulation combined with specific tasks, and volitional muscle contraction-triggered stimulation that was synchronized with tasks. Motor capabilities of the hand and arm were improved after the rehabilitation. Conclusions: EMG-triggered electrical stimulation may be more effective than non-triggered electrical stimulation in facilitating the hand functions in stroke patients in terms of muscle strength and voluntary muscle contraction of the paretic hand and arm. Triggered electrical stimulation can be even more effective when it is combined with specific tasks.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.275-284
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• 2011

The accuracy simulation technology of linear motion system is introduced in this paper. Motion errors and positioning errors are simulated using informations on the design parameters of elements of linear motion system. 5 Degree-of-freedom motion error analysis algorithm utilizing the transfer function method and positioning error analysis algorithm which are main frame of accuracy simulation are introduced. Simulated motion errors are compared with experimental results for verifying the effectiveness. Then, using the proposed algorithms, simulation is performed to investigate the effects of ballscrew and linear motor on the motion errors. Finally, the influence of feedback sensor position on the positioning error is also discussed.

• 한국HCI학회:학술대회논문집
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• 2008.02c
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• pp.25-29
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• 2008

A virtual prototyping (VP) system provides realistic 3D images of product. A virtual prototype, however, can only be operated using traditional input device like keyboards or mice and cannot present physical interface of the product. This paper describes a haptic dial system for virtual prototyping, which integrates haptic effects with virtual user interface to facilitate product development. A user can interface the virtual prototype with the motor-driven haptic dial with feeling like operating mechanical dial. This system will help product designers sketch user interfaces during the whole stage of product design.

• The KSFM Journal of Fluid Machinery
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• v.7 no.5 s.26
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• pp.13-19
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• 2004

Centrifugal blowers are widely used for air handling units in industry applications. The blower has a centrifugal impeller and a scroll casing including a driving component such as an electric motor. The impeller takes forward or backward blades to induce flows into the blower, Comprehensive investigation according to the two kinds of blades is systematically carried out for a guidance of design for this kind research. It is observed that flow rate of the blower with forward blades is larger than that of the system with backward blades. Otherwise, the system noise is more pronounced in the case of the blower with forward blades. The reason is due to larger velocity from the rotating forward blades that pose obtuse angle with the circumferential direction. The distinguished characteristics are validated by a parallel experiments with a wind tunnel and in an anechoic chamber. Numerical analysis for the system shows detail information inside the blades and the casing. A series of figures to show the flow details offer deep understanding of the performance of a centrifugal blower with different blades.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.87-94
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• 2005

This paper investigates the constant-level luffing and time optimal control of jib cranes. The constant-level luffing, which is the sustainment of the load at a constant height during luffing, is achieved by analyzing the kinematic relationship between the angular displacement of a boom and that of the main hoist motor of a jib crane. Under the assumption that the main body of the crane does not rotate, the equations of motion of the boom are derived using Newton's Second Law. The dynamic equations for the crane system are highly nonlinear; therefore, they are linearized under the small angular motion of the load to apply linear control theory. This paper investigates the time optimal control from the perspective of no-sway at a target point. A stepped velocity pattern is used to design the moving path of the jib crane. Simulation results demonstrate the effectiveness of the time optimal control, in terms of anti-sway motion of the load, while luffing the crane.