• Journal of the Society of Naval Architects of Korea
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• v.45 no.3
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• pp.303-308
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• 2008

The induction heating is more efficient for a plate bending because of its easy operation and control of working parameters, compared with the heating by a gas torch. The existing axis symmetric analysis method could neither handle initial curved plates nor be used in the optimization of coil shapes because of its limit of an axis symmetric coil shape. But the proposed method using some discrete part models and analysis processes could overcome these difficulties and show more accurate results in temperatures and deflections of flat or curved plates with initial curvature than those in the existing axis symmetric analysis method. This method is composed of the multi-disciplinary analyses such as an electro magnetic analysis, a heat transfer analysis and a deformation analysis based on inherent strain approach per each step. Traditionally, the coil shape in the induction heating is circular shape and it needs the moving process along heating lines. To overcome this, the 'Long Type Coil' with some linear parallel coils was proposed. It did not need the moving process along heating lines and reduced the heating process time. The results of experiments were compared with those of the simulation.

• Wind and Structures
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• v.29 no.1
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• pp.15-32
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• 2019

Much advancement has been made in wind power due to modern technological developments. The wind energy technology is the world's fastest-growing energy option. More power can be generated from wind energy by the use of new design and techniques of wind energy machines. The geographical areas with suitable wind speed are more favorable and preferred for wind power deployment over other sources of energy generation. Today's wind turbines are mainly the horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). HAWTs are commercially available in various sizes starting from a few kilowatts to multi-megawatts and are suitable for almost all applications, including both onshore and offshore deployment. On the other hand, VAWTs finds their places in small and residential wind applications. The objective of the present work is to review the technological development, available sizes, efficiencies, structural types, and structural stability of VAWTs. Structural stability and efficiencies of the VAWTS are found to be dependent on the structural shape and size.

• Journal of Welding and Joining
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• v.13 no.4
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• pp.122-131
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• 1995

An automatic welding equipment for thick plates requires the capability of the seam tracking of the weld line which often includes misalignment of the workpiece and variation of groove width. In this study, an automatic welding equipment and control algorithms based on the arc sensor were proposed for the GMA welding of thick plates which had misalignment and gap variation. The developed system being constituted with 5 axis can be automatically controlled by computer and also automnatically set the welding conditions such as welding current, and voltage. The proposed algorithms for the seam tracking in multi-pass welding of the thick plates were constituted as follows : the detection of weaving-end point for findng the variation of groove width, the control of welding velocity for acquiring a constant thickness deposition of weld metal, and the calculation of groove width and height of an arbitrary pass in the multi-pass weld. As results of the application of the system, it was revealed that the system had a good capability in seam tracking and made an excellent weld quality in V groove butt joint.

• Journal of Biomedical Engineering Research
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• v.36 no.6
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• pp.271-275
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• 2015

The aim of this study was to develop a multi-nozzle based bioprinting system for fabrication of three-dimensional (3D) biological structure. In this study, a thermoplastic biomaterial that has relatively high mechanical stability, polycaprolactone (PCL) was used to make the 3D structure. A multi-nozzle bioprinting system was designed to dispense thermoplastic biomaterial and hydrogel simultaneously. The system that consists of 3-axes of x-y-z motion control stage and a compartment for injection syringe control mounted on the stage has been developed. Also, it has 1-axis actuator for position change of nozzle. The controllability of the printed line width with PCL was tested as a representative performance index.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.1
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• pp.1-10
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• 2017

Recently, with the ever-increasing complexity of industrial robot systems, it has been greatly attention to adopt a multi-core based motion controller with high cost-performance ratio. In this paper, we propose a software architecture that aims to utilize the computing power of multi-core processors. The key concept of our architecture is to use shared memory for the interplay between threads running on separate processor cores. And then, we have integrated our proposed architecture with an industrial standard compliant IDE for automatic code generation of motion runtime. For the performance evaluation, we constructed a test-bed consisting of a motion controller with Preempt-RT Linux based dual-core industrial PC and a 3-axis industrial robot platform. The experimental results show that the actuation time difference between axes is 10 ns in average and bounded up to 689 ns under $1000{\mu}s$ control period, which can come up with real-time performance for industrial robot.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.126-132
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• 2002

Robot manipulator has highly nonlinear dynamics. Therefore the control of multi-link robot arms is a challenging and difficult problem. In this paper an independent joint adaptive fuzzy sliding mode scheme is developed leer control of robot manipulators. The proposed scheme does not require an accurate manipulator dynamic model, yet it guarantees asymptotic trajectory tracking despite gross robot parameter variations. Numerical simulation for independent joint control of a 3-axis PUMA arm will also be included.

• KIEAE Journal
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• v.11 no.1
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• pp.9-14
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• 2011

Currently, the multi-residential apartments used in Korea are mostly bearing wall apartments which don't satisfy consumers for the lack of architectural plan flexibility. And due to remodelling-incompatible, bearing wall apartments have to be reconstructed. It is, thus, necessary to develop multi-residential apartments utilizing composite beam that can replace the conventional bearing wall-type apartment buildings. Composite beams proposed in this paper ensure modification of space and quality control, while the floor heights are maintained at the same floor height as in bearing wall structures. This study analyzes the experimental behavior of composite beams with proper combination of structural steel, reinforced concrete, and precast concrete. By comparing with the theoretical analysis and experimental results, the accuracy of flexural moment capacity and neutral axis was evaluated. The experiments were performed by two simply-supported specimens using loading and unloading. When the analysis results were compared with the experimental results, the flexural moment capacity of the composite beam was shown with an error of approximately -0.5 to 0.1% at the maximum load limit state.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.52-56
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• 2006

This paper presents a cross-eye characteristics of multi-path wave scattering. Cross-eye method uses the phase differences of multi signals and is used fur electronic protection. When a signal is propagated from transmitter to receiver on the ground surface, direct wave and reflected wave signals are combined in front of the receiving antenna with different phases. To calculate and control the amplitude and phase of reflected signal, we have developed a cross eye electronic protection method for radar system and studied the variation of electric power density.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.168-175
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• 2011

Contouring accuracy of CNC machine tools is very important for high-speed and high-precision machining. In particular, large contour error may occur during corner tracking. In order to reduce the corner contouring error, acceleration and deceleration control or tool-path planning methods have been suggested. However, they do not directly control the corner contouring error. In the meantime, network servo systems are widely used because of their easiness of building and cost effectiveness. Communication latency between the master controller and servo drives, however, may deteriorate contouring accuracy especially during corner tracking. This paper proposes a control strategy that can accurately calculate and directly control the corner contouring error. A prediction control is combined with the above control to cope with communication latency. The proposed control method is evaluated through computer simulation and experiments. The results show its validity and usefulness.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.55-61
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• 2003

Control of multi-link robot arms is a challenging and difficult problem because of the highly nonlinear dynamics. Independent joint adaptive scheme is developed for control of robot manipulators based on Sugeno-type of fuzzy logic. Fuzzy logic system is used to approximate the coupling forces among the joints, coriolis force, centrifugal force, gravitational force, and frictional forces. The proposed scheme does not require an accurate manipulator dynamic, and it is proved that closed-loop system is asymptotic stable despite the gross robot parameter variations. Numerical simulations for three-axis PUMA robot are included to show the effectiveness of controller.