• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.125-129
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• 1996

In this study, a method is proposed for the cutting force prediction of Ball-end milling process using Z-map is proposed. Any types of cutting area generated from previous cutting process can be expressed in z-map data. Cutting edge of a ball-end mill is divided into a set of finite cutting edges and the position of this edge is projected to the cross-section plane normal to the Z-axis. Comparing this projected position with Z-map data of cutting area and determining whether it is in the cutting region, total cutting force can be calculated by means of numerical integration. A series of experiments such as side cutting and upward/downard cutting was performet to verify the simulated cutting force.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1267-1273
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• 2009

Hot press forming can produce high-strength components by rapidly cooling between closed punch and die after hot forming using quenchable boron steel austenized in a furnace. In the hot press forming process, the cooling rate is influenced by the size, position and arrangement of the cooling channel and the file condition of cooling water in the die. Also, mechanical properties of the final components and operation time are related to cooling rate. Therefore, the design of optimized cooling channel is one of the most important works. In this paper, the effect of position and size of the cooling channel on the cooling rate was investigated by using design of experiment and FE analysis in hot press bending process. Therefore the optimum cooling channel ratio was presented in the HPB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.736-741
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• 2004

In high-capacity disk drives with ever-growing track density, the allowable level of position error signal (PES) is becoming smaller and smaller. In order to achieve the high TPI disk drive, it is necessary to improve the writing accuracy during the STW(servo track writing) process through the reduction of TMR sources. Among the main contributors of the NRRO(Non-Repeatable Run-out) PES, the disk vibration and the HSA(head-stack assembly) vibration is considered to be one of the most significant factors. Also the most contributors of RRO(Repeatable Run- out) come from the contributors of NRRO which is written-in at the time of STW(servo track writing) process. In this paper, the experimental test result shows that the effect of NRRO on servo written-in RRO effectively can be reduced through a STW process under low dense medium condition such as semi-vacuum.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.1
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• pp.7-14
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• 2006

In this paper, an in-process diagnosis method for performance of position control servo system was studied, which was based upon null bias, slew-rate ratio and delay time measurement. Slew-rate ratio and delay time were analyzed by theoretical analysis, computer simulation and experiment. As a result of these analysis, when spool of servovalve was weared, slew-rate ratio was decreased and delay time was increased.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.263-268
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• 2001

A new control scheme s proposed for the control of reactive batch distillation (RBD) column. A nonlinear wave model captures the essential dynamic behavior of the RBD process. The proposed control scheme is based on both Generic Model Control(GNC) and nonlinear wave model. The control scheme uses a profile position of the column as a controlled variable. Ethanol esterification process using RBD is chosen as an example process. Tight control of the distillate purity is obtained with the use of the proposed control scheme.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.1-6
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• 2009

This paper presents a geometrical error compensation of tool alignment for sharp edge bite on B axis controlled machine. In precision micro patterning, bite alignment is crucial parameter for machined surface. To decrease bite alignment error, plus tilted bite from B axis center is touched to reference work piece(pin gauge) and checked the deviation from original position. Same process is repeated for maximum touch deviation value. From this touched position value, wheel alignment error in X axis and Z axis can be calculated on B axis center. Experimental results show that this compensation method is efficient to correct sharp edge bite alignment.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.9
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• pp.417-422
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• 2001

The brushless DC motor(BLDCM) is widely used in many applications. One of the application of the BLDCM is the stage which is one of process in the semiconductor manufacturing processes. Very high performance is required in the stage process. In this paper, the 1 degree of freedom positioning system for the basic technology of the stage is studied. The linearization method is proposed to make the controller design procedures easy by measuring the thrust force ripple using the strain gauge. And through the experiments, it is proved that the inner velocity control loop is necessary to make more precise positioning control system.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.238-239
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• 2006

Nozzle geometry influences gas dynamics making sprayed particle behavior one of the most important parameters in cold spray process. Gas flows at the entrance convergent section of the nozzle takes place at relatively high temperature and are subsonic. Thus, this region is a very suitable environment for heating spray particle. In this study, numerical simulation and experiments were conducted to investigate the effect of nozzle contour, entrance geometry of nozzle and powder injection position at nozzle on the cold spray process. The process changes were observed through numerical simulation studies and the results were used to find a correlation with coating properties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1380-1383
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• 2004

The scanning type XY stage is frequently used these days as precision positioning system in equipment for semiconductor or display element. It is requested higher velocity and more precise accuracy for higher productivity and measuring performance. The position accuracy of general stage is primarily affected by the geometric errors caused by parasitic motion of stage, misalignments such as perpendicular error, and thermal expansion of structure. In the case of scanning type stage, H type frame is usually used as base stage which is driven by two actuators such as linear motor. In the point view of scanning process, the stage is used in moving motion. Therefore, dynamic variation is added as significant position error source with other parasitic motion error. Because the scanning axis is driven by two actuators with two position detectors, 2 dimensional position errors have different characteristic compared to general tacked type XY stage. In this study 2D position error of scanning stage is analyzed by 1D heterodyne interferometer calibrator, which can measure 1D linear position error, straightness error, yaw error and pitch error, and perpendicular error. The 2D position error is evaluated by diagonal measurement (ISO230-6). The yaw error and perpendicular error are compensated on the base stage of scanning axis. And, the horizontal straightness error is compensated by cross axis compensation. And, dynamic motion error in scanning motion is analyzed.