• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.164-167
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• 1997

The die wear is one of the main factors affecting die accuracy and tool lifetime. It is desired to reduce die wear by developing simulation method to predict wear based on process parameters, and then optimize the process. Therefore, this paper describes disign methodology of preform for minimizing wear of finisher die in multi-stage cold forging processes. The finite element method is combined with the routine of wear prediction and the cold forging processes. The finite element method is combined with the routine of wear prediction and the cold forging process is analyzed. In order to obtain preform to minimize die wear, the FPS algorithm is applied and the optimal preform shape is found from iterative deformation analysis and wear calculation.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.11
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• pp.591-598
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• 2000

In this thesis, a digital tracking controller is proposed for multi-axis position control system. Tracking and contouring error exist when the machine tool moves along a trajectory in multi-axis system. The proposed scheme enhances the tracking and contouring performance by reducing the errors. Also, an optimal tracking controller reduces the tracking error by the state feedback and the feedforward compensator reduces the effects of a nonlinear disturbance such as friction or dead zone. The proposed control scheme reduces the contour error which occurred when the tool tracks the reference trajectory. Finally, the performance of the proposed controller is exemplified by some simulations and by applying the real XY servo system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.124-131
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• 1996

The use of small hemispherical high-speed precision bearing has increased drastically these days in the field of computer disk driver, highteech devices as well as communication and electronic device drivers. It was suggested that the new polishing process adopting the diamond grinding wheel and polishing tool instead of multi stage lapping processes, which enables the mass production of the bearing by reduction of polishing time. Polishing mechanism was analysed and the results were applied to the design and manufacturing of the polishing system. Experiments for selection of optimal polishing conditions were carried out using the polishing system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.458-461
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• 2005

In this paper, a new type of inchworm motion actuator is developed in fabrication of actuators for micro-press machine. This is consisted of three piezoelectric actuators, one is for moving the tool guide and the other are for clamping the guide. The inchworm motor provides both high load and large displacement in small size actuator. PZT has compressive strength and often fails under tensile stress and pulling. Thus, in order to prevent failure, we have designed pre-load housing and accomplished FEM analysis. The pre-load housing was used for determining the optimal design condition by comparing the von-mises stresses with the change of hinge stiffness. Also, in order to predict the performance of the motor under certain conditions, the system model was simulated using MATLAB. This is open loop control actuator and driven by the period of input voltage.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.124-129
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• 2001

The experimental study was the cutting characteristics of non-ferrous metals. The experimental apparatus was used the turning machine and diamond tool. This aimed at lading the optimal cutting conditions by measuring surface farm and roughness. Used non-ferrous metals were aluminum, brass and oxygen-free copper. As well, according to changing cutting conditions such as feed rate by measuring cutting farce and surface roughness and according to cutting conditions the non-ferrous metals studied about cutting properties.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.229-234
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• 1999

This thesis presents the design method using CAE(Computer Aided Engineering) with the consideration of reliability for optimal gear driving system. The validity and feasibility of the proposed method are verified by the application to transmission of machine tool. The reliability and life analysis is based on the two-parameter Weibull distribution lives of the gears and bearings. Ninety-percent of reliability life is the life of the component or system in million output rotations or hours at which ninety percent of identical components or system would survive under the given loading conditions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.101-106
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• 2008

In the wire cut electrical discharge machining, the optimal machining parameters setting satisfying the requirements of both high efficiency and good quality is very difficult because its process involves a series of complex physical phenomena and the machining parameters are numerous over diverse range. In this paper, the experimental investigation has been performed to find out the influence of the machining parameters on the machining performance such as cutting speed and surface roughness. The selected experimental parameters are no load voltage, discharge peak current and pulse-off time. The experimental results give the guideline for selecting suitable machining parameters.

• Nuclear Engineering and Technology
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• v.29 no.1
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• pp.68-77
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• 1997

The reactor power control system is described in the fashion of the order increased LQR system. To obtain the optimal state feedback gain vectors, the weighting matrix of the performance function should be determined. Since the contentional method has some limitations, stochastic searching methods are investigated to optimize the LQR weighting matrix using the modified genetic algorithm combined with the simulated annealing, a new optimizing tool named the hybrid MGA-SA is developed to determine the weighting parameters of the LQR system. This optimizing tool provides a more systematic approach in designing the LQR system. Since it can be easily incorporated with any forms of the cost function, it also provides the great flexibility in the optimization problems.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.37-44
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• 2005

In this paper, wire electrochemical machining (Wire ECM) with ultra short pulses is presented. Platinum wire with $10{\mu}m$ diameter was used as a tool and 304 stainless steel was locally dissolved by electrochemical machining in 0.1M $H_{2}SO_4$ electrolyte. Wire ECM can be easily applied to the fabrication of arbitrarily shaped micro-grooves without tool wear. The change of machining gap according to applied pulse voltage, pulse on-time and pulse period was investigated and the optimal pulse condition for stable machining was obtained. Using this method, various micro-grooves with less than $20{\mu}m$ width were fabricated.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.75-81
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• 1999

In order to remain competitive, a manufacturing company needs to maintain the optimal condition of its manufacturing system. Machine tools as an important element of a manufacturing system consist of complex mechanical as well as electronic components. Therefore, diagnosing the troubles of machine tools is a tricky process which requires a lot of experience and knowledge. Since providing machine tool users with necessary services at the right time is very difficult and expensive, a remote diagnosis system is to be regarded as a good alternative, with which users can diagnose and fix the machine troubles. This paper presents a framework for a remote machine tools diagnosis system by combining the world wide web technology and backward reasoning expert system.