• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.169-172
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• 2004

The effect of the process parameters on the stable lifetime in rapid thermal firing(RTF) was investigated in order to optimize the process for the Cz-silicon. The process temperature was varied between $700^{\circ}C\;and\;950^{\circ}C$ while the process time was chosen 1 s and 10 s. At below $850^{\circ}C$ the stable lifetime for 10 s is higher than that for 1 s and increases with increasing by the process temperature. However, at over $850^{\circ}C$ the improved stable lifetime is not dependent on the process time and temperature. On the other hand, two high temperature processes in solar cell fabrics are combined with the optimized process and the non-optimized process. The last process determines the stable lifetime. Also, the degraded stable lifetime could be increased by processing in optimized process. The decreased lifetime can increase using the optimized oxidation process, which is a final process in solar cells. Finally, the optimized and non-optimized processes are applied solar cells.

• Transactions of Materials Processing
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• v.29 no.4
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• pp.218-228
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• 2020

The prediction of final mass and optimized process conditions of injection molded products using Artificial Neural Network (ANN) were demonstrated. The ANN was modeled with 10 input parameters and one output parameter (mass). The input parameters, i.e.; melt temperature, mold temperature, injection speed, packing pressure, packing time, cooling time, back pressure, plastification speed, V/P switchover, and suck back were selected. To generate training data for the ANN model, 77 experiments based on the combination of orthogonal sampling and random sampling were performed. The collected training data were normalized to eliminate scale differences between factors to improve the prediction performance of the ANN model. Grid search and random search method were used to find the optimized hyper-parameter of the ANN model. After the training of ANN model, optimized process conditions that satisfied the target mass of 41.14 g were predicted. The predicted process conditions were verified through actual injection molding experiments. Through the verification, it was found that the average deviation in the optimized conditions was 0.15±0.07 g. This value confirms that our proposed procedure can successfully predict the optimized process conditions for the target mass of injection molded products.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.39-45
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• 1999

The procedure of robotic Gas metal Arc (GMA) welding in order to achieve the optimized bead geometry needs the selection of suitable process parameters such as arc current, welding voltage, welding speed. It is required the relationships between process parameters and bead geometry. The objective of this paper is to develop the algorithm that enables the determination of process parameters from the optimized bead geometry for robotic GMA welding. It depends on the inversion of empirical equations derived from multiple regression analysis of the relationships between the process parameters and the bead dimensions using the least square method. The method not only directly determines those parameters which will give the desired set of bead geometry, but also avoids the need to iterate with a succession of guesses employed Finite Element Method(FEM). These results suggest that process parameter from experimental equation for robotic GMA welding may be employed to monitor and control the bead geometry in real time.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.113-119
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• 2010

Hydroforming is the technology that utilizes hydraulic pressure to form tube or sheet materials into desired shapes inside die cavities. Tube hydroforming provides a number of advantages over the conventional stamping process, including fewer secondary operations, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength. In many case, hydroformed parts have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study for the numerical process design FE analysis was performed with DYNAFORM 5.5. Die parting angle and circumferential expansion ratio was optimized. With optimized condition, bulge and hydroforming experiments to form flange were performed. Forming characteristic at various pressure conditions was analyzed and optimized internal pressure condition was evaluated. The results show that flanged parts can be successfully produced by tube hydroforming process.

• Design & Manufacturing
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• v.15 no.2
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• pp.17-22
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• 2021

The shape of the blank greatly affects the formability and quality of the product after the stamping process. In this study, the geometry of the B-Pillar blank in the stamping process was optimized using design of experiments. The geometry of the blank for the B-pillar was simplified with the two length values and two radius values. The effects of design variables were studied through the Design of experiments. The stamping process of the B-pillar was predicted with the Finite Element Analysis (FEA). The optimized blank geometry was obtained. It results in the reduced maximum equivalent plastic strain. The local necking and the wrinkling did not occurred with the optimized blank geometry.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.169-171
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• 2003

In this paper, the prediction for the optimized bead geometry such as bead width, height, penetration and bead area in the Gas Metal Arc (GMA) welding with Taguchi method is presented. An orthogonal array, and the Signal-to-Noise (S/N) ratio employed to investigate the welding quality characteristics together in the selection of process parameters in the GMA welding process, to analyze the effect of each process parameter on the bead geometry and to finally determine the process parameters with the optimal bead geometry. Experimental results fi-om this research show that the Taguchi method provides an effective tool to enhance the accuracy of the optimized bead geometry.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.303-311
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• 2012

In this study, we introduce a dynamic process model as well as the design methodology of optimized fuzzy controller for its efficient application to vacuum production system to produce a semiconductor, solar module and display and so on. In a vacuum control field, PID control method is widely used from the viewpoint of simple structure and preferred performance. But, PID control method is very sensitive to the change of environment of control system as well as the change of control parameters. Therefore, it's difficult to get a preferred performance results from target system which has a complicated structure and lots of nonlinear factors. To solve such problem, we propose the design methodology of an optimized fuzzy PID controller through a following series of steps. First a dynamic characteristic of the target system is analyzed through a series of experiments. Second the process model is built up and its characteristic is compared with real process. Third, the optimized fuzzy PID controller is designed using genetic algorithms. Finally, the fuzzy controller is applied to target system and then its performance is compared with that of other conventional controllers(PID, PI, and Fuzzy PI controller). The performance of the proposed fuzzy controller is evaluated in terms of auto-tuned control parameters and output responses considered by ITAE index, overshoot, rise time and steady state time.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.1-6
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• 2014

PID(Proportional, Integral, Derivative) controller is one of the most used process controllers in nuclear power plants. The optimized parameter setting of process controller contributes to the stable operation and efficiency in the operating nuclear power plants. PID parameter setting is tuned when new process control system is established or process control system is changed. It is a burdensome work for I&C(Instrument and Control) engineers to tune the PID controller because it requires a lot of experience and knowledge. When the plant is in operation, inadequate PID parameter setting can be the cause of the unstable process of the plant. Therefore the results of PID parameter setting should be compared, simulated, verified and finally optimized. The practical PID tuning methods used in process controller are tuning operation calculation(Ziegler-Nicholes, Minimum TIAE, Lambda, IMC), exclusive tuning program based on computer and Matlab application. This paper introduces the various tuning methods and suggests an optimized PID tuning process in the operating nuclear power plants.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.17-18
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• 2022

In Korea, asbestos removal has been actively carried out nationwide since 2015 when asbestos was completely banned as a first-class carcinogen. Since scattering dust generated in the process of removing asbestos causes fatal diseases such as asbestos lung disease and lung cancer, concerns are growing over the safety of construction workers and building users undergoing dismantling. For this reason, regulations on asbestos sites have been strengthened and prior studies on safety and risk assessment have been conducted, but research on actual site data collection and process planning is insufficient even though safety is reduced due to delay in site construction period. Therefore, it is necessary to analyze the work and delay factors of the asbestos dismantling process and develop an optimized process plan model for workers. This study is an initial step to develop an optimized process plan model that considers the safety and productivity of asbestos dismantling work, and aims to help establish an optimized process plan for asbestos dismantling process using website clone simulation.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.106-110
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• 2001

A effective and accurate method of hot-forging process is essential to the design of optimized dies as well as workpiece of intial shape. the former is achieved by a proper forging sequence with invokes serious problem like excessive load and die wear, die failure, underfilling and lap defects. the latter is achieved by a proper preform design of case I, case II, case III. metal forming processes of aluminum-alloy forged at an effective strain and temperature are analyzed by the finite element method. the non-isothermal analysis have been compared with optimized in terms of preform shape.