• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.44-49
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• 1999

This paper is concerned with the theoretical and experimental study on the force conrtrol of a miniature robotic gripper. The gripper is an uniform flexible cantilever equipped with a distributed set of compact force sensor. As an actuator piezoelectric acturator, piezoelectric acturator is fixed with cupper plate at which the beam is clamped. The mathematical model of the assembled electro-mechaincal system is developed. The force sensor is described by a set of concentrated mass-spring system. The formulated equations of motion are applied to he study of a control problem where the gripper is commanded to grip an object The usefulness of the PID control technique is verified by experiment.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.111-118
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• 2007

Hydroforming is a cost-effective way of shaping malleable metals such as steel into lightweight, structurally stiff and strong pieces. With the increased use of the hydroformed components in automotive and aerospace industries, it is important to know the variations of the mechanical properties in the hydroforming process far the safe and durable design purposes. The principal goal of this paper is to suggest a procedure to evaluate the variations of tensile and fatigue properties before and after a hydroforming process. A miniature specimen, which is 0.2 mm thick and 2.3 mm wide, is devised and tested to measure local mechanical properties. The effects of specimen size, defects, surface roughness, and hydroforming on the tensile and fatigue behaviors are discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.10a
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• pp.33-43
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• 1994

A series of tensile tests have been performed to investigate the hardening behavior of rolled steel sheets. Tensile tests consist of three stages. At the 1st stage, full size tensile specimens were prestrained in the direction of rolling, then mid-sized tensile specimens were cut from the gauge sections of the full size specimens at angles to the rolling direction. At the 2nd stage, mid-sized specimens were prestrained by predetermined magnitudes of strains and miniature tensile specimens were prepared from each of the mid-sized specimens at every 10 degrees. At the final stage, from tests on miniature tensile specimens the hardening behavior of the prestrained sheets has been investigated. According to the experimental results, orthotropic symmetry is reserved during tensile elongation, and one of the orthotropy axes is continuously rotated to specimen axis. Existing theories seem to fail to explain the rotation of orthotropy axis. A new phenomenological model is proposed to explain the strain induced rotation of orthotropy axes.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.89-96
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• 2007

In this paper, a new air bearing stage with magnetic preload and a linear motor has been developed for the small precision machine systems. The new air bearing stage is unique in the sense that permanent magnets attached bottom of the iron core of table are used not only for preloading air bearings in vertical direction but also for generating thrust force by current of the coil at base. The characteristics of air bearings using porous pads were analyzed with numerical method, and the magnetic circuit model was derived for linear motor for calculating required preload force and thrust force. A prototype of single axis miniature stage with size of $120(W){\times}120(L){\times}50(H)\;mm^3$ was designed and fabricated and examined its performances, vertical stiffness, load capacity, thrust force and positioning resolution.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.424-430
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• 2010

In coherent anti-Stokes Raman scattering (CARS) microscopy reported until now, conventional microscope objectives are used, so that they are limited for introduction into a living body. Gradient-index (GRIN) rod lenses might be a solution for miniaturized microscope objectives for in-vivo CARS microscopy. However, due to the inherent large amount of chromatic aberration, GRIN rod lenses cannot be utilized for this purpose. CARS imaging catheter, composed of miniaturized microscope objective and fiber bundle, can be introduced into a living body for minimally invasive diagnosis. In order to design the catheter, we have to first investigate design requirements. And then, the optical design is processed with design strategies and intensive computing power to achieve the design requirements. We report the miniaturized objective lens system with diffraction-limited performance and completely corrected chromatic aberrations for an in-vivo CARS imaging catheter.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.27-32
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• 2010

The OMM(On-Machine-Measurement) system has many advantages compare to conventional measurement in the way the time and cost. But, the sensor suitable to OMM system is restrictive use. Touch trigger probe sensor has long time for measurement and non-contact sensor has directional demerit. Because the long mechanical parts such as gear and lead screw for pump, injector and machine tools has big and heavy, unclamp and transferring for measurement in machining process is very difficult. This paper presents a development of ultra miniature eddy current displacement sensor with 3 axes for On-Machine-Measurement system. The accuracy of the sensor is experimentally proved in the grinding machine. In experimental results, the accuracy has under ${\pm}5\;{\mu}m$.

• Journal of the Korean Ceramic Society
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• v.30 no.8
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• pp.643-650
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• 1993

NdAl3(BO3)4 have been developed for miniature solid state laser material. Single crystals of NdAl3(BO3)4 were grown by TSSG technique using BaB4O7 flux. The effects of growth conditions such as cooling rate, seed orientation and rotation speed on crystal quality and the morphology were studied. At the cooling rate of 2.4$^{\circ}C$/day and the crystal rotation speed of 30~40rpm with the seed orientation in <201> or <100> directions, transparent and light violet colored crystals in size of 10$\times$15$\times$20㎣ with well developed {010}, {111}, {111}, {021}, {001}, {102}, {112}, {021} faces were obtained. By X-ray diffraction analysis, the space group was determined as C2/c, and the X-ray powder data was obtained.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.107-113
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• 2011

This study was performed for the application of the exposure limit in work field and the relative noxious gas concentration was estimated by using a miniature ship. The noxious gas concentration about light and shade number distribution of measuring subject field was estimated by using floating visualization image from a miniature ship in a large wind tunnel. About the concentration estimation, the correlation of concentration distribution drawn from the existing experimental results was used, the estimation result satisfied LTEL standard.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.31.2-31.2
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• 2005

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.22-22
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• 2004