• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.413-416
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• 2007

In general, by means of the electrodepositing technique, a copper foil sample was prepared with a high purity and a high density. But the mechanical properties of the electrodepositing copper foil was lower than it's the rolling copper foil. However, the production of copper foil with approximately 36 microns thick in rolling process was very difficult. This paper describes the outline of the high accuracy cold rolling in 6 high mill which was developed for the purpose of rolling very thin accurate gauge copper foil(36 micron thick), and give several rolling characteristic of 600 mm wide copper foil. a) Large strain can be accumulated pass by pass in industrial multi-pass rolling processing to overcome large critical strain for thickness accuracy through optimization of rolling schedule. b) Also, permissible tension for rolling 0.45 $\sim$ 0.036 mm thick copper strip stably in accordance with the each pass work had been established by FEM simulation results. c) During the plate rolling process, considerable values of the forces of material pressure on the tool occur. These pressures cause the elastic deformation of the roll, thus changing the shape of the deformation region. A numerical simulation of roll deflection during cold rolling is presented in the paper. d) The proposed pass schedule can roll very thin copper foil of 36 micron thickness to a tolerance of ${\pm}1$ microns. The validity of simulated results was verified into rolling experiments on the copper foil.

• Transactions of Materials Processing
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• v.9 no.2
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• pp.112-119
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• 2000

The roll Pass design is one of the most important processes to design the whole equipment of the rods and bars rolling system. In this study, the roll pass design program named TollRo(Rolling Factory Organizer) was developed. conventional methods to design roll pass were analyzed and a new algorithm to design the dimension of the intermediate groove was introduced. Object oriented programming technology was implemented in this design program. It comprises GUI(Graphic User Interface), function of automatic pass design, function of modifying pass schedule and database of material properties. The developed program can be used to design roll pass with consistency for the rods and bars rolling system. The man-hours for the whole design can be drastically reduced. The design parameters of rolling system can be extracted quickly by this program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.813-814
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• 2008

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.666-673
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• 2008

To construct the accurate radio satellite navigation system, the efficient communication each satellite with the ground station is very important. Throughout the communication, the orbit of each satellite can be corrected, and those information will be used to analyze the satellite satus by the operator. Since there are limited resources of ground station, the schedule of antenna's azimuth and elevation angle should be optimized. On the other hand, the satellite in the medium earth orbit does not pass the same point of the earth surface due to the rotation of the earth. Therefore, the antenna pass schedule must be updated at the proper moment. In this study, Q learning approach which is a form of model-free reinforcement learning and genetic algorithm are considered to find the optimal antenna schedule. To verify the optimality of the solution, numerical simulations are conducted.

• Transactions of Materials Processing
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• v.14 no.9 s.81
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• pp.785-790
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• 2005

High-speed multi-pass wet wire drawing has become very common for production of high-carbon steel cord because of the increase in customer demand and production rates in real industrial fields. Although, the wet wire drawing process is performed at a high speed usually above 1000m/min, greater speed is required to improve productivity. However, in the high-carbon steel wire drawing process, the wire temperature rises greatly as the drawing speed increase. The excessive temperature rise makes the wire more brittle and finally leads to wire breakage. In this study, the variations in wire temperature during the multi-pass wet wire drawing process were investigated. A multi-pass wet wire drawing process with 21 passes, which is used to produce steel cord, was redesigned by considering the increase in temperature. Through a wet wire drawing experiment, it was possible to increase the maximum final drawing speed to 2000m/min.

• Transactions of Materials Processing
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• v.26 no.1
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• pp.28-34
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• 2017

Multi-pass shape rolling is performed to produce long products of arbitrary cross-sectional shapes. In the past, the multi-pass shape rolling process has been designed by the trial and error method or the experience of experts based on the empirical approach. Particularly, the design of roll caliber in shape rolling is important to improve product quality and dimensional accuracy. In this paper, the caliber design and pass schedule of multi-pass shape rolling were proposed for manufacturing piston ring wire. In order to design roll caliber, major shape parameter and dimension was determined by analysis of various caliber design. FE-simulation was conducted to verify effectiveness of proposed process design. At first, forming simulation was performed to predict shape of the product. Then, fracture of the wire was evaluated by critical damage value using normalized Cockcroft-Latham criteria. The experiment was carried out and the results are within the allowable tolerance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.427-430
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• 2005

Improving the productivity of steel cord is required due to the increase in demand for it, even though steel cord being used as a reinforcement of a tire has been produced at multi-pass wet wire drawing process over 1000m/min. To improve the productivity, if just increase drawing speed, it causes temperature rise, fracture arisen by embrittlement during drawing process. To increase drawing speed affecting productivity, the variation of wire temperature during multi-pass wet wire drawing process is investigated in this study. In result, the multi-pass wet wire drawing process is redesigned. The redesigned wet drawing process with 27 passes efficiently controls wire temperature during drawing process. It, therefore, enables drawing process to be possible at ultra high speed with 2000m/min. It becomes possible to improve the productivity of steel cord in this paper because the increase in drawing speed could be achieved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1844-1853
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• 2001

In the present investigation, it was attempted to design the rolling pass schedule fur a clean steel of 0.1C-1.5Mn-0.25Si with the objective of the austenite grain refinement. As the method of approach, a coupled mathematical modeling technique was proposed which consists of a recrystallization model and a flow stress modes. The validity of the coupled model was examined through comparison with results of continuous and discontinuous compression tests at various temperatures, strains and strain rates. The coupled model was incorporated with the finite element method to set up a systematic design methodology far the rolling path schedule for austenite grain refinement. Two path schedules were obtained and discussed in the paper with regard to rolling path time, average grain size, grain size deviation in thickness, etc.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.291-295
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• 2003

The occurrence of ductile fracture is the working limit of many metal forming processes. It is necessary to predict the criteria and to apply the condition in a process design. Over the years. the way for clarifying conditions have been studied and presented. However such a way needs lots of experiments and analysis. In this study, in order to determine the critical damage value of a used material Cu 4N, it was performed a tensile test and FEM analysis by using DEFORM 2D. For applying the obtained critical damage value it was also performed a upsetting test by using DEFORM 2D. The way of determining a critical damage value which is presented in this study will make possible to find easily it which is one of the working limit factor. And the way of determining a critical damage value will make possible to find in multi-pass drawing process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1095-1105
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• 1993

Shape rolling processes to produce H-section beams are numerically simulated by the simplified three-dimensional finite element method. The 2-dimensional finite element method, used for the generalized plane strain condition, is combined with the slab method. Computer simulation results of the 19-passes in H-section beam rolling in practice include the grid distortions, the cross-sectional area changes, the roll separating forces, and the roll torques. Also, the amount of side spread can be found during the multi-pass rolling simulations. The finite element mesh system is remeshed with I-DEAS whenever the billet distorts severely. This study would contribute to CAD/CAM of shape rolling process through the optimal roll pass schedule.