• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.66-72
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• 2006

The old technique of sandblasting which has been used for paint or scale removing, deburring and glass decorating has recently been developed into a powder blasting technique for brittle materials, capable of producing micro structures larger than $100{\mu}m$. In this paper, we studied on the predictive modeling of material removal and surface roughness in powder blasting of glass by design of experiments. The surface characteristics and surface shape of powder blasted glass surface were tested under different blasting parameter. Finally, we proposed a predictive model for powder blasting process, and compared with experimental results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.435-440
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• 2000

In this study, we aims to develop the machining technology for the ultra precision surface and profile accuracy. For this purpose, we construct the electrolytic in process grinding system (ELID grinding) and apply to the cylindrical and internal grinding. Through the various machining experiments such as SCM steel., ceramics, tungsten carbide etc., we have obtained nanometer surface roughness. And we have applied this mirror grinding technique to hydraulic manual valve and mold core of mini disk optical pick-up base. For the development of fine mechanical part machining technology, e have made multi fiber optical connector using fine grinding technology. And constructed micro drilling system with process monitoring system which is possible to drill 50${\mu}{\textrm}{m}$ diameter hole.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.387-392
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• 1999

The micro electronic control technology with developing microcomputers make great contribution to electrohydraulic control systems. The electrohydraulic pulse control simplifies in conjunction with power electronic amplifier and high speed operated solenoid valves. It is necessary to valves to convert electronic pulse signal to hydraulic pulse flow as fast as possible. This study deals with the speed control of an oil hydraulic motor operated by two way high speed solenoid valves. The valves acts as converters of electronic-pulse signals to hydraulic power. By constructing systems in which a hydraulic motor is operated by two solenoid valves, the pulse with modulation method (PWM) has adopted as the speed control of hydraulic motor systems. The static and dynamic characteristics of the systems are investigated by the experiment. It is clarify that a hydraulic motor operated PWM show good performance as a control component, achieving accurate velocity control.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.519-524
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• 1999

To manufacture alumina products, sintering and grinding process are needed. In Al2O3 grinding, macro/micro surface fracture and cracks are easily occurred on the ground surface because of its high brittleness. In view point of fatigue fracture, surface profile produced by grinding is considered as notches. Therefore, it was reasonable that magnitudes and shapes of surface profiles effects on fatigue strength and life. Particularly, surface finish of Al2O3 which have high hardness and brittleness have an effect on fatigue strength. In this paper, some experiments are carried out to examine influence of grinding conditions to magnitude and shape of surface profile as well as the relationships of Ra, Rmax, Rmax/Ra, and Ku. Through the experimental results, It is found that Ra and Rmax was affected by grinding conditions, but Rmax/Ra and Ku was not. There are linear relations between Ra and Rmax, and between Rmax/Ra and Ku.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.585-590
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• 2000

Recently, It is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic Signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of Ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research, considering a thin film below the limit of ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic Signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness, sound velocity, and step height, regardless of interference phenomenon. Numeral information was deduced and quantified effective information from the image. Also, pattern recognition of a defected input image was performed by neural network algorithm. Input pattern of various numeral was composed combinationally, and then, it was studied by neural network. Furthermore, possibility of pattern recognition was confirmed on artifical defected input data formed by simulation. Finally, application on unknown input pattern was also examined.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.335-341
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• 2005

The development of Shadow Moire in many kinds of methods for acquiring 3-dimensional information from an object is written in this paper. The fringe is appeared, when a grating mask makes its shadow on the object. The object is moved along x-axis more then 3 times to get phases from its fringe that contains data of the object's height. PMP{Phase Measuring Profilometry) is used for analyzing these images from a CCD camera. The calculated phase is remedied for expending the restricted results due to range of the $tan^{-1}$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.19-23
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• 2005

In order to develop a high brightness ion source using plasma, the ion beam extraction system with an aperture of $100{\mu}m$ in diameter has been designed and constructed. It is observed that over 500nA of He ion beam current can be extracted. With such an optimized condition, $\~10^3\;A/cm^2sr$ beam brightness can be measured by emittance scanner, which is believed to be a promising result for developing next generation FIB.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.40-44
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• 2005

Recently PZT is used in ultra precision mechanism field. PZT itself has a small driving range although it has a high resolution. Many methods, such as inchworm, impact driving, inertial sliding method, etc., have been applied for moving range expansion. In this study, a new actuating mechanism for rotational motion with two driving PZT is proposed. The Fixed-Fixed beam support is applied for compensation of the difference in driving force between expansion and contraction of PZT. The behavior and design parameters of the proposed mechanism are analyzed for improving performance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.3-8
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• 2005

We introduced mechanical stimuli and micropatterned substrate with micro fibers to investigate the effects of those on neurite outgrowth along with nerve growth factor (NGF) in vitro. Microfiber substrates were fabricated using an electrospinning process. And PC-12 cells cultured on substrates were simulated with nerver growth factor and laminar flow shear stress in a fluid flow system The results suggest that microfiber substrates and fluid-induced shear stress are promising for simulating neuronal regeneration in a desired direction.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.52-60
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• 2005

Ultra-precision positioning systems basically require high natural frequency and sufficient workspace. To cope with this requirement, flexure hinge mechanisms have been developed. However, previous designs are difficult to satisfy the functional requirements of the system due to difficulty in modeling and optimization process applying fur the independent axiomatic design. Therefore, this paper suggests a new design and design procedure based on semi-coupled, axiomatic design. A spatial 3-DOF parallel type micro mechanism is chosen aa an exemplary device. Based on preliminary kinematic analysis and dynamic modeling of the system, an optimum design is conducted. To check the effectiveness of the optimal parameters obtained by theoretical approach, simulation has been performed by FEM.