• Proceedings of the KWS Conference
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• 2009.11a
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• pp.29-29
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• 2009

On this research, laser welding technology for manufacturing automobile body is studied. Laser welding technology is one of the important technologies used in the manufacturing of lighter, safer automotive bodies at a high level of productivity; the leading automotive manufacturers have replaced spot welding with laser welding in the process of car body assembly. Korean auto manufacturers are developing and applying the laser welding technology using a high output power Nd:YAG laser and a 6-axes industrial robot. On the other hand, the robot-based remote laser welding system was equipped with a long focal laser scanner system in robotic end effect. Laser system, robot system, and scanner system are used for realizing the high speed laser welding system. The remote laser welding system and industrial robotic system are used to consist of robot-based remote laser welding system. The robot-based remote laser welding system is flexible and able to improve laser welding speed compared with traditional welding as spot welding and laser welding. The robot-based remote laser systems used in this study were Trumpf's 4kW Nd:YAG laser (HL4006D) and IPG's 1.6kW Fiber laser (YLR-1600), while the robot systems were of ABB's IRB6400R (payload:120kg) and Hyundai Heavy Industry's HX130-02 (payload:130kg). In addition, a study of quality evaluation and monitoring technology for the remote laser welding was conducted. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity and temperature by using UV and IR detectors. Over the past years, Trumf's 4kW Nd:YAG laser and ABB's IRB6400R robot system was used. Nowadays, the new laser source, robot and laser scanner system are used to increase the processing speed and to improve the efficiency of processes. This paper proposes the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.269-274
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• 2004

Current delivery system, in which the analog current produced by a unique DAC circuit is stored into a current-memory circuit and delivered in a time-divided sequence, shows variation of output current as low as 4% in a current source data-driver IC for AM-OLED driven by a current-programmed method without any fuse repairing after fabrication. This driver IC has 54 outputs and can sink constant current as low as 3 ${\mu}A$ with 6-bit analog levels. Such a low current level without variation can hardly be obtained by an ordinary MOS transistor because the current level is in the sub-threshold region and changes exponentially with threshold voltage variation. Thus we adopted a current mirror circuit composed of bipolar transistors to supply well-controlled current within a nano-ampere range.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.5
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• pp.831-836
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• 2013

This study demonstrates the process of fabricating patterns using tribonanolithography (TNL),with laboratory-made micro polycrystalline diamond (PCD) tools that are attached to an atomic force microscope (AFM). The various patterns are easily fabricated using mechanical scratching, under various normal loads, using the PCD tool on single crystal silicon, which is the master mold for replication in this study. Then, polydimethylsiloxane (PDMS) replica molds are fabricated using precise pattern transfer processes. The transferred patterns show high dimensional accuracy as compared with those of TNL-processed silicon micro molds. TNL can reduce the need for high cost and complicated apparatuses required for conventional lithography methods. TNL shows great potential in that it allows for the rapid fabrication of duplicated patterns through simple mechanical micromachining on brittle sample surfaces.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.45-50
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• 2006

This paper shows a new precision actuator of MUTM(miniature universal testing machine) for the testing of compression and tensile load on the MEMS materials and structures. The MUTM consists of a sample holder, an ultraprecision precision actuator(tranlation stage) and load sensor. The precision actuator has been developed for generating displacements with nanometer accuracy and a dynamic range of 1mm simultaneously. In this paper, it can be made by using the displacement property of bi-morph type PZT, which is able to extend the long range(stroke) according to cantilever size. However, it is not enough to be generated for compression and tensile load in miniature universal testing machine. Therefore, three dozen bi-morph type PZTs are used for generating the load. The load and displacement of the precision actuator are 35g and 0.4mm respectively.

• Advances in nano research
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• v.6 no.2
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• pp.93-112
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• 2018

An analytical solution of the buckling governing equations of functionally graded piezoelectric (FGP) nanobeams obtained by using a developed third-order shear deformation theory is presented. Electro-mechanical properties of FGP nanobeam are supposed to change continuously in the thickness direction based on power-law model. To capture the small size effects, Eringen's nonlocal elasticity theory is adopted. Employing Hamilton's principle, the nonlocal governing equations of a FG nanobeams made of piezoelectric materials are obtained and they are solved using Navier-type analytical solution. Results are provided to show the effect of different external electric voltage, power-law index, nonlocal parameter and slenderness ratio on the buckling loads of the size-dependent FGP nanobeams. The accuracy of the present model is verified by comparing it with nonlocal Timoshenko FG beams. So, this study makes the first attempt for analyzing buckling behavior of higher order shear deformable FGP nanobeams.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.94-100
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• 2010

Nowadays, several nontraditional machining(NTM) processes are widely used to machine a complex and accurate shape part of hard materials, such as titanium, ceramics, high strength temperature resistant and refractory materials which are difficult to machine and having high strength, hardness, toughness. Machining of these complex shapes in such materials by traditional machining processes are very difficult. The NTM processes is important in the areas of micro- and nano scale machining, where high accuracy and superior surface characteristics are required, which can only be achieved using these NTM processes. So, for effective selection of different NTM processes, careful decision making for a given NTM application is often necessary. An appropriate NTM process for a given material and shape condition is very difficult for the novice engineers. In this paper, an expert system based on an analytic network process(ANP) is suggested for a best selection of NTM process in a NTM application considering an prior interdependency effect among various factors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.313-317
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• 2005

Precision motor dynamometer is requiring for nano positioning control performance recently. Particularly, linear motor is using rapidly and the dynamometer needs is increasing. In this study, a precision control dynamometer is designed using MR (Magnetic Rheological) damper. The ultra precision motor system including the driver and controller is tested using the MR damper dynamometer. This dynamometer is able to measure torque for rotary motor or traction force with linear positioning accuracy for linear motor system.

• Advances in nano research
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• v.5 no.1
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• pp.35-47
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• 2017

This paper deals with free vibration analysis of nanosize rings and arches with consideration of surface effects. The Gurtin-Murdach model is employed for incorporating the surface effect parameters including surface density, while the small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. An analytical Navier solution is presented to solve the governing equations of motions. Comparison between results of the present work and those available in the literature shows the accuracy of this method. It is explicitly shown that the vibration characteristics of the curved nanosize beams are significantly influenced by the surface density effects. Moreover, it is shown that by increasing the nonlocal parameter, the influence of surface density reduce to zero, and the natural frequency reaches its classical value. Numerical results are presented to serve as benchmarks for future analyses of nanosize rings and arches.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.78-81
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• 2003

Polishing Processes are widely used in the glass, optical, die and semiconductor industry and are conventionally carried out using abrasive slurry and a polishing pad. But abrasive slurry process has a weak point that is high cost of handling of used slurry and hard controllability of slurry. Recently, some researches have attempted to solve these problems and one method is the development of a fixed abrasive pad. FAP has a couple of advantages including clean environment, lower CoC, easy controllability and higher form accuracy. But FAP also has a weak point that is need of dressing because of glazing and loading. The paper introduces the basic concept and fabrication technique of FAP using hydrophilic polymers with swelling characteristics in water and explains the self-conditioning phenomenon. Experimental results demonstrate to achieve nano surface roughness of soda lime glass for optical application

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1207-1210
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• 2003

This paper deals with experiments for dynamic characteristics and performance evaluation of the 3-axis fine positioning stage developed in [1]. The features of the developed fine positioning stage are the long stroke due to the magnetically preloaded PZT actuators, the minimum motion crosstalk due to the use of a ball contact mechanism and the compact design. The dynamic characteristics of the actuator and the stage are tested with the preload changed in order to validate the actuator and the stage design. Performance evaluation is also made for the PZT actuators as well as the stage positioning accuracy. Experimental results show that the developed stage is accurate enough to be used for nanometer positioning.