• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.115-120
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• 2000

Increasing demands on precision machining of free-form surface have necessitated that the tool to move not only position error as small as possible, but also with smoothly varying feedrates. This paper presents new algorithm for high precision 3D(3-dimensional) NURBS(Non-Uniform Rational B-Spline) interpolation in the reference-pulse technique. Based o the minimum path error strategy, interpolation algorithm was designed to follow the NURBS curve. Using this algorithm a real-time 3D NURBS interpolator was developed in software. The algorithm implemented in a PC showed promising results in interpolation error and speed performance. It is expected that this can be applied to the CNC systems for the high precision machining of complex shapes.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.94-100
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• 1999

This study adopted the ultra precision machining system which was composed of an air bearing spindle, a granite bed, air pad and a linear feeding mechanism. It also applied the cutting experiment on the aluminum alloy. To evaluate the safety of high speed machining, we examined the surface roughness according to the changes of cutting speed and obtained the speed limit. This paper also studied the effect of cutting condition such as feed rates and depths of cut on the surface roughness within the speed limit. This provided practical information regarding ultra precision machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.156-160
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• 1997

This paper introdues the development of hydraulic cylinder with magnetic sensor detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position witha little displacement by using algorithm for recognizing datum points, 1/4 divider algorithm and high precision algorithm improved position precision and robustness to noise etc. The solenoid valve and PWM control using saw-toothed wave are used for absolute position control of cylinder, respectively

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1032-1035
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• 2000

Increasing demands on precision machining with computerized numerical control (CNC) machines have necessitated that the tool to move not only position error as small as possible, but also with smoothly varying feedrates in space. This paper presents a new high precision interpolation algorithm for 3-dimensional (3D) Non-Uniform Rational B-Spline (NURBS) curve in the reference-pulse CNC technique. Based on the minimum path error strategy, real-time NURBS interpolator was developed in software and this was implemented with a PC-NC milling machine. The several experimental results have shown that the proposed NURBS interpolator is useful for the high precision machining of complex shapes. It is expected that this algorithm can be applied to the CNC machines for the machining of 3D free-form surfaces.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.708-717
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• 2003

With the development of precision manufacturing technologies, the importance of precision positioning devices is increasing. Conventional actuators, dual stage or mechanically contacting type, have limitation in coping with performance demands. As a possible solution, magnetic suspension technology was studied. Such a contact-free system has advantages in terms of high accuracy, low production cost and easy adaptability to high precision manufacturing processes. This paper deals with magnetically suspended multi-degrees of freedom actuator which can realize large linear motion. In this paper, the operating principle is explained with the magnetic force analysis, and the equations of motion are derived. Experimental results of the implemented system are also given.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.859-866
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• 2010

Generally, a fixed type guide-bush system is installed during machining miniature work-pieces with high precision in the multi-task CNC lathe. But a conventional guide-bush system does not provide a constant clamping force under the condition of varying work-piece diameters. It is important to maintain a constant clamping force for guaranteeing machining precision. This paper proposes a new guide-bush system with a pneumatic clamping device for the CNC Swiss-turn lathe to keep constant clamping force with changes in work-piece diameters. Through performance tests, new clamping system developed in the study showed better machining precision at the cost of a small increase in the temperature of the system than conventional systems due to an increase in the frictional heat and a change in the heat transfer route.

• Journal of Korean Association for Spatial Structures
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• v.15 no.4
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• pp.57-64
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• 2015

The construction of vinyl greenhouses are increasing because of economic feasibility, construction period, and construction regulations. However, the vinyl greenhouses are apt to collapse by snow load since they have a small member as a temporary structure. The 3 types of buckling such as global, member and nodal buckling could be occurred to arched structures according to characteristics of cross section. To examine the member buckling, the precision of analysis need to be enhanced. In that case, we can examine the characteristics of the those buckling. The purposes of this study are to verify buckling characteristics of structures using the method of high precision analysis with a center node of member. The results of high precision analysis bring member buckling, and in the analysis method having the center node of member, the value of strength is getting lower than a previous study.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.68-75
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• 2003

This paper introduces the development of hydraulic cylinder with magnetic sensors detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position with a little displacement by using algorithm for recognizing datum points, 114 divider algorithm and high precision algorithm improved position precision. We alse evaluate the developed system under the load disturbance and add band pass filter to the previous's signal process circuit for the protecting magnetic sensors's saturation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.72-78
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• 2001

Roundness measurement method using three displacement sensors makes in-process roundness measurement possible on the NC machine because it eliminates the vibration signal and eccentricity signal from measured roundness signal from the workpiece. But there are noises in measured signals, it isn't possible to measure the roundness with high precision. In this study, a high precision in-process roundness measurement system is development, which can eliminate vibrations of the spindle by using three displacement sensors and which can also estimate the noisy roundness measurement signals by applying Kalman filter.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.491-495
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• 2014

We developed a compact high-precision slot-die coating machine for thin-film deposition on a flexible substrate. For smooth and precise coating, air-bearing and linear motor system were employed to minimize velocity ripple. The gap control mechanism is specially designed to have repeatability of gap between nozzle and substrate under 1 ${\mu}m$. Due to extremely precise gap control, the machine can coat thin-films down to 50 nm with $200mm{\times}100mm$ size. A thin film of Ag nano-particle ink is coated for demonstration.