• Journal of Power System Engineering
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• v.4 no.2
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• pp.25-30
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• 2000

The grinding process is very complex and relates many parameters to control the process. As this reason, a theoretical analysis and a quantitative estimation of the grinding process has not been well established. In this study, the in-process monitoring system was suggested by applying the neural network for monitoring and shooting the malfunction of cylindrical plunge grinding process. This system used the power signals from the electric power meter. This neural network was composed of processing elements [4-(5-5)-3] with 4 identified power parameters. Because sensitivity is blunted some minute vibration components, the simulation result of this system has appeared about 10% erroneous recognition in the uncertain pattern and the average success rate of the trouble recognition was about 90%. Consequently, the developed system, which applied to the power signals, can be recognize enough to monitor the grinding process as in-process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.720-725
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• 2013

Power MOSFET operate voltage-driven devices, design to control the large power switching device for power supply, converter, motor control, etc. We have analyzed trench process, field limit ring process for fabrication of unified trench gate power MOSFET. And we have analyzed electrical characteristics of fabricated unified trench gate power MOSFET. The optimal trench process was based on SF6. After we carried out SEM measurement, we obtained superior trench gate and field limit ring process. And we compared electrical characteristics of planar and trench gate unified power MOSFET after completing device fabrication. As a result, the both of them was obtained 500 V breakdown voltage. However trench gate unified power MOSFET was shown improved Vth and on state voltage drop characteristics than planar gate unified power MOSFET.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2327-2337
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• 2016

The mode-switching control of transient process is important to grid-connected 400 Hz solid-state power supply systems. Therefore, this paper analyzes the principle of on-grid and islanding operation of the system with or without local loads in the grid-connected process and provides a theoretical study of the effect of different switching sequences on the mode-switching transient process. The conclusion is that the mode switch (MS) must be turned on before the solid-state switch (STS) in the on-grid process and that STS must be turned off before the MS in the off-grid process. A strategy of mode-switching smooth control for transient process of the system is proposed, including its concrete steps. The strategy utilizes the average distribution of peak currents and the smooth adjustment of peak currents and phases to achieve a no-shock grid connection. The simulation and experimental results show that the theoretical analysis is correct and that the method is effective.

• Transactions of Materials Processing
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• v.9 no.3
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• pp.265-273
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• 2000

The conventional and new forging processes of the power steering worm blank are analyzed by the rigid-plastic finite element method. The conventional process contains three stages such as indentation, extrusion and upsetting, which was designed by a forming equipment expert. Process conditions such as reduction in area, semi-die angle and upsetting ratio are considered to prevent internal or geometrical defects. The results of simulation of the conventional forging process are summarized in terms of deformation patterns, load-stroke relationships and die pressures for each forming operation. Based on the simulation results of the current three-stage, the power steering worm blank forging process for improving the conventional process sequence is designed. Die pressures and forming loads of proposed process are within limit value which is proposed by experts and the proposed process is found to be proper for manufacturing the power steering worm blank.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.290-294
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• 2014

PID(Proportional, Integral, Derivative) controller is the most popular process controllers in nuclear power plants. The optimized parameter setting of the process controller contributes to the stable operation and the efficiency of the operating nuclear power plants. PID parameter setting is tuned when new process control systems are installed or current process control systems are changed. When the nuclear plant is shut down, a lot of PID tuning methods such as the Trial and Error method, Ultimate Oscillation method operation, Ziegler-Nichols method, frequency method are used to tune the PID values. But inadequate PID parameter setting can be the cause of the unstable process of the operating nuclear power plant. Therefore the results of PID parameter setting should be simulated, optimized and finally verified. This paper introduces the simulation method of PID tuning to optimize the PID parameter setting and confirms them of the actual PID controller in the operating nuclear power plants. The simulation method provides the accurate process modeling and optimized PID parameter setting of the multi-loop control process in particular.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.5-12
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• 2002

The grinding process has been mainly used fur finishing metal products as final machining stage. But chatter vibration and bum of a workpiece have a bad effect on the machined surface and should be detected in modern grinding process. This paper deals with a fault detection of the cylindrical plunge grinding process by power parameters. During the grinding process the power signals of an induced motor were sampled and used to determine the relationship between fault and change of power parameters. A neural network was used far detecting the grinding fault and an influence of power parameters to the grinding fault was analyzed.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1311-1317
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• 2010

A continuous time asymmetric power GARCH(1,1) model is suggested, based on a single background driving L$\'{e}$vy process. The stochastic differential equation for the given process is derived and the strict stationarity and kth order moment conditions are examined.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.128-131
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• 2004

In this study Bosch etching process repeating etch and deposition by STS-ICP ASEHR was evaluated. Fundamentally etch depth changes were affected by thickness of deposited PR, $SiO_2$ and depth, and pattern size on the substrate. However etch rates were observed to be changed by variable parameters such as platen power, coil power, and process pressure. Etch rate showed $1.2\mu{m}/min$ and sidewall profile showed $90\pm0.2^\circ$ with platen power 12W, coil power 500W, and etch/passivation cycle 6/7sec. It was confirmed that this result was very typical to Bosch process utilizing ICP.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.384-387
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• 1999

A new multi-seeding process for the growth of YBa$_2Cu_3O_x$ single crystals was developed. This process introduces an additional heating step to peritectic temperature and a subsequent slow cooling step to the growth temperature following the point when the crystals contacted. The crystal growth was resumed thereafter. The results obtained with this new process were compared with those of the conventional growth process, in which materials were only kept at the growth temperature. There was significant improvement in trapped magnetic field over the conventional multi-seeding process, which is believed to be due to complete elimination of liquid phase between crystals.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.154-158
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• 2004

Power inductor is usually used in the field of the power circuit of a cellular phone, TFT LCD module etc.. This paper presents the development process of Power Inductor Full Automation Winding/Welding System for TFT LCD. This process, the process algorithm, high precision welding current control, design of welding head, high speed, high precision feeding mechanism, and user interface process control program technologies are included.