• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.377-384
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• 2007

A backscatter Kikuchi diffraction attachment to an SEM enables the convenient investigation of grain orientations on bulk or micro surface. Their relation to micro structural features gives insight into many aspects of anisotropic materials properties. In micro area such as Micro Electro Mechanical Systems(MEMS) devices is required in order to improve understanding of how they may be expected to perform upon the micro scale. Electro Back Scatter Diffraction (EBSD) helps us to find uniform area as MEMS material. The ${\gamma}-TiAl$ has two different lamellar structures ${\gamma}/{\alpha}2-Ti_3Al$ phase which have shows $\{111\}{\gamma}//\{0001\}{\alpha}2$ plane indexing. The micro size testing specimen was successfully made by this structural relation. Interlamellar structure specimen averagely show $20{\sim}25%$ lower fracture toughness value compare with translamellar specimens Moreover micro fracture surface and micro crack progress were observed.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.94-103
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• 2003

In case of environment requiring safety such as human body and requiring flexible shape, a conventional mechanical actuator system does not satisfy requirements. Therefore, in order to solve these problems. a research of various smart material such as EAP (Electro Active Polymer), EAC (Electro Active Ceramic) and SMA (Shape Memory Alloy) is in progress. Recently, the highest preferring material among various smart material is EP (Electrostictive Polymer), because it has very fast response time, powerful force and large displacement. The previous researches have been studied properties of polymer and simple control, but present researches are studied a polymer actuator. An EP (Electostrictive Polymer) actuator has properties which change variably ils shape and environmental condition. Therefore, in order to coincide with a user's purpose, it is important not only to decide a shape of actuator and mechanical design but also to investigate a efficient controller. In this paper, we constructed the control logic with an adaptive fuzzy algorithm which depends on the physical properties of EP that has a dielectric constant depending on time. It caused for a sub-actuator to operate at the same time that a sub-actuator system operation increase with a functional improvement and control efficiency improvement in each actuator, hence it becomes very important to manage it effectively and to control the sub-system which Is operated effectively. There is a limitation on the management of Main-host system which has multiple sub-system, hence it brings out the Multi-Vehicle Control process that disperse the task efficiently. Controlling the multi-dispersion system efficiently, it needs the research of Main-host system's scheduling, data interchange between sub-actuators, data interchange between Main-host system and sub-actuator system, and data communication process. Therefore in this papers, we compared the fuzzy controller with the adaptive fuzzy controller. also, we applied the scheduling method for efficient multi-control in EP Actuator and the algorithm with interchanging data, protocol design.

• Progress in Superconductivity
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• v.14 no.1
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• pp.60-65
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• 2012

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. A 35 kWh class SFES module was designed and constructed as part of a 100kWh/1MW class SFES composed of three 35 kWh class SFES modules. The 35 kWh class SFES is composed of a main frame, superconductor bearings, a composite flywheel, a motor/generator, electro-magnetic bearings, and a permanent magnet bearing. The high energy density composite flywheel is levitated by the permanent magnet bearing and superconductor bearings, while being spun by the motor/generator, and the electro-magnetic bearings are activated while passing through the critical speeds. Each of the main components was designed to provide maximum performance within a space-limited compact frame. The 35 kWh class SFES is designed to store 35 kWh, with a 350 kW charge/discharge capacity, in the 8,000 ~ 12,000 rpm operational speed range.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.73-81
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• 2001

The MIAB welding uses a rotating arc as its heat source and is known as an efficient method fur pipe butt welding. The arc is rotated around the weld line by the electro-magnetic force resulting from the interaction of arc current and magnetic field. The electro-magnetic force is affected by magnetic flux density, arc current, and arc length. Especially, the magnetic flux density is an important factor on arc rotation and weld quality. This paper presents a 2D finite element model for the analysis of magnetic flux density in the actual welding conditions. The magnetic flux density is mainly dependent on gap between two pipes, the position of coil from gap center, exciting current, and relative permeability. Thus, the relations between magnetic flux density and main factors were investigated through experiment and analysis. Experiments were performed for the steel pipes(48.1mm O.D and 2.0mm thickness). The analysis results of magnetic flux density reveal that it increases with increasing exciting current, increasing relative permeability, decreasing distance from gap center to coil, and decreasing gap size. It is considered that the results of this study can be used as important data on the design of coil system and MIAB welding system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.154-154
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• 2006

Samsung Electro Mechanics ink jet has developed ultra high resolution alignment system. The alignment system has been developed for repeatable printing of conductive ink. The resolution of alignment system is 0.5um and the velocity of printing working plate is 1.5m/s. So far repeated printing results included sintering process have over 30um of drop mislocation data. In order to improve line thickness and conductivity of metal line, we need to develop the higher mechanical accurate align system. On the demand, this developed align system has under $1{\sim}2{\mu}m$ mispositioning performance and can measure of mechanical accuracy of inkjet printer, as well as the straightness of jetted drop from inkjet head. There is no kinds limit of substrate and ink to use SEM alignment system. By using this alignment system, we progress two experiment of reiterate printing drop and making conductive line on the glass and photo paper. Optical microscope and 3D profiler has been used for measurement of printed ink.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.71-78
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• 2002

This paper is concerned with the design and implementation of magnetic damper system to reduce the vibration of suspension system actively. Cylindrical type electro-magnetic actuator with permanent magnet is analyzed and effective controller design is made. Magnetic force analyzed and transfer function for the total system is determined by experimental data using error minimization method. For experiments, simple suspension structure system is utilized, in which a magnetic damper composed of permanent magnet and digital controller is attached. In order to drive the system, bipolar power amplifier of voltage control type is utilized. Stable and high speed control board is used to perform digital control logic for the given system. This paper shows that the magnetic damper system using phase-lead controller excellently reduces vibration of 1-D.O.F (degree of freedom) suspension system.

• Journal of Digital Contents Society
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• v.13 no.1
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• pp.129-139
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• 2012

Recently, the smart sensor technologies are rapidly developing in accordance with the technology of implementation in small-size, low-cost, and low power consumption. With these sensor technologies, especially with MEMS and NEMS, the researches on the WSN are actively performing. For the WSN, a network security function is essential even it requires high physical resource level. But the WSN with the smart sensor technologies could not be provided with enough resources for the function because of limited size, computing-power, low-power, and etc. In this paper, we introduce security and key-management protocols of WSN.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1988-1991
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• 2005

A micro fluid actuator driven by electromagnetic force at MEMS(Micro Electro Mechanical System) level has been designed. The operation of the actuator was simulated in three steps. First, fluid flow analysis has been performed to determine the actuator load. With the load, dynamic behavior of the actuator structure has been analysed. Finally, fluid-structure interaction analysis has been performed to predict the performance of the actuator. To avoid excessive amount of computation, axisymmetric and plane strain 2-D models were used.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.837-843
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• 2016

This paper presents a position control strategy for a pump-controlled electro-hydrostatic actuator (EHA) using feedforward control with disturbance compensation. As the disturbance observer is used to estimate nonlinear dynamics of EHA, which has valve-opening conditionals, as well as external disturbances, an additional feedforward control is adopted to achieve rapid response. The effectiveness of the proposed control strategy is verified through experiment using an EHA test bench. The proposed controller shows better tracking performance compared with a conventional PID controller.

• Smart Structures and Systems
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• v.12 no.6
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• pp.679-694
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• 2013

In this paper the application of the Interpolation Damage Detection Method to the numerical model of a suspension bridge instrumented with a network of Micro-Electro-Mechanical System sensors is presented. The method, which, in its present formulation, belongs to Level II damage identification method, can identify the presence and the location of damage from responses recorded on the structure before and after a seismic damaging event. The application of the method does not require knowledge of the modal properties of the structure nor a numerical model of it. Emphasis is placed herein on the influence of recorded signals noise on the reliability of the results given by the Interpolation Damage Detection Method. The response of a suspension bridge to seismic excitation is computed from a numerical model and artificially corrupted with random noise characteristic of two families of Micro-Electro-Mechanical System accelerometers. The reliability of the results is checked for different damage scenarios.