• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1025-1028
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• 2002

In this paper, a micro-turning lathe is introduced for micro machining of aluminum rod. To give feed motion, stepwise motion[2] actuators are used instead of the conventional inchworm mechanism. These are consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The guide is V-form. The linearity and positional accuracy of the actuators is good enough far high precision motion. Since the system is more compact than the conventional system using three Piezoelectric ceramics, it is applicable for the micro-machine or MEMS unit. To fabricate the lathe, a small spindle unit with ball bearings of diameter of 10 millimeter is built-up on the top the slider. The motion is feed backed with miniaturized linear encoder attached each axis slider. The diamond tool bite is used for cutting tool. The machining is tried to make small diameter rod. The possible diameter that can be machined in this machine is presented as well as chip formation, surface roughness, and machinability.

• Journal of Ginseng Research
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• v.24 no.4
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• pp.188-195
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• 2000

Using Ginseng saponins (crude saponin and total saponin) and ginsenoside Rbl Rb2, Rc, Rd, Re, Rhl, and Rh2 in this study, we have examined the effects of the compounds on the induction of differentiation in normal rat mammary epithelial cells and 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor cells in culture. When normal rat mammary organoids were cultured in 100-mm culture plates in the presence or absence of ginseng saponins, there were four different cell colonies after two weeks in culture: cobble stone, spindle, honey comb, and senescence type colonies. Ginseng saponins showed different effects on the development of each colonies. Scrape-loading dye transfer tech-nique was performed to measure the effects of total saponin, Rhl, and Rh2 on intercellular junctional communication. Intercellular communication was not observed at short cultilral time, e.g., four or seven days, but when it cultured it up to two weeks, cell to cell communication was observed in saponin-treated cells. Reconstituted basement membrane, Matrigel, supported the growth and development several different multicellular structures from normal mammary organoids (e.g., ductal, webbed, stellate, and squamous colonies) or DMBA-induced mammary tumor (e.g., alveolar unit, foamy alveolar unit, squamous metaplasia, lobule-ductal, stellate, and webbed colony). In ginseng saponin-treated groups, webbed colonies were more and squamous colonies were less than control group. Moreover, the ductal colonies, marker tructure of well-differentiate mammary epithelial cells, were developed more in saponin-treated group than in control group. In conclusion, ginseng saponins affected on the differentiation of normal rat mammary epithelial cells and DMBA-induced mammary tumor cells in culture.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.214-219
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. In this study, the compensation device and temperature-based algorithm have been presented in order to compensate thermal error of machine tools under the real-time. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.120-128
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of $\pm$2${\mu}{\textrm}{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be improved by using the developed measurement system when the spherical ball artifact is mounted on the modular fixture.

• Advances in materials Research
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• v.2 no.4
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.329-334
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• 2004

This paper proposes Internet-based checking scheme for machine-tools with a variant CNC. Checking points defined in this research are classified into two categories such as structured point and operational point. The formal includes the vibration of bearing, temperature of spindle unit and another periodical management. And the latter includes oil checking, clamp locking/unlocking and machining on/off status. Through this research, for the global management of variant CNC machines interspersed with CAC and OAC in manufacturing system, the suitable environment for Internet-based checking of variant CNC machines was designed and the checking methods for CAC and OAC machines were compared with each other.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.99-104
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• 2004

Micro/meso cutting is getting more important in the fields of precision machining technology. A micro-turning lathe is one of parts to consist the Micro Factory. It accepts stepwise motion actuators that are used for feeding system instead of the conventional mechanism. It is consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The linearity and positional accuracy of the actuators are good enough for high precision motion. The spindle unit is operated with DC motor on the top of the slider. The motion is communicated with miniaturized linear encoder attached on each side of axis. A mono crystal diamond tool is used for cutting tool. This micro-lathe has been made a machining experiment to see the characteristics of micro-machining.

• Transactions of Materials Processing
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• v.16 no.2 s.92
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• pp.132-137
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• 2007

A double roll rotary forming equipment is presented in this paper. The equipment is developed for joining the socket with the ball of a concave piston assembly with its geometrical tolerance requirements satisfied. The equipment is composed of a lathe, a double roll system and a roll pressing unit driven by the hydraulic system. The workpiece rotates by spindle chuck of the lathe while the double roll system approaches perpendicularly to the central line of the workpiece. The equipment is successfully applied to precision joining of the ball and the socket fur the concave piston assembly of a high pressure hydraulic pump.