• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.373-375
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• 2008

In this paper the arc behavior in spiral type vacuum interrupter was analyzed by observing taken photographs from high-speed digital camera(10000frame/second) and current-voltage waveform from oscilloscope. As a result, the influence of twisting angle between contacts on arc behavior could be analyzed by matching and comparing arc voltage and photographs simultaneously.

• Textile Coloration and Finishing
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• v.12 no.2
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• pp.79-88
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• 2000

Draw textured yarns have many differences with yarn quality as well as wearing, due to the bulkiness, thermal and physical properties according to the false twist texturing system. In order to improve such property, many studies have been accomplished for developing good textured yarns and their fabrics, but these have been essentially obtained by experimental data or mathematical analysis. This study surveyed various properties of DTY produced by false twist texturing system, namely pin and crossed-belt false twist insertion systems. And 6 yarn specimens of 2 group(pin twisting type, belt twisting type) were measured and analysed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.31-34
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• 2004

A new extrusion process of the circular section product with helical fins could be developed by using rotating extrusion dies. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion dies, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion dies is needed to rotate itself instead of twisting billet. And in order to rotate dies, the shape of inside contour of extrusion dies must have conical type with twisted Inclined die surface connecting the die entrance section and the die exit section linearly. The results of experiments show that, in spite of using twisted extrusion dies, twisting of the billet should not happen because of rotating dies in the opposite direction of twisting direction of billet during extruding billet, and, from the results, it shows that it can decrease the power of extrusion pressure and could prevent crack of teeth for fin forming.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.803-810
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• 2009

Micromirrors have a wide range of applications such as optical switches, laser scanners, and digital projection displays. Due to their low performances and high costs, however, practical applications of micromirrors are quite limited. At present micromirrors demand not only a better design but also a simple fabrication process. In this study a twisting-type micromirror that can be driven by two thermal bimorph actuators bending in opposite directions is designed from electro-thermo-mechanical theories and fabricated through a simple MEMS process. Each actuator consists of $SiO_2$ and gold thin-film layers. Simplified analytical model has been built to optimize the performance of micromirror. Due to unexpected resistance increase of metal film and alignment mismatch during fabrication process, experimental rotation angles of micromirrors are about $11^{\circ}$ at applied voltages less than 0.6V. From numerical simulation and analytical studies, however, the next design can provide rotation angles over $20^{\circ}$ at the same applied voltage.

• Journal of Acupuncture Research
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• v.35 no.4
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• pp.238-243
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• 2018

Background: Various factors can alter the efficacy of acupuncture treatment, such as the location of points, manipulations, depth of insertion, needle retention time, and needle type. In this study, the effect of needle diameter on the efficacy of acupuncture treatment was quantitatively evaluated. Methods: Five acupuncture needles of different diameters used in clinical practice were compared. Force on the porcine tissue phantom was measured using a sensor. Lifting-thrusting and twisting-rotating movements were performed using a needle insertion-measurement system. After repeated measurements, force magnitude was calculated and compared. Following this, we correlated needle diameter and force magnitude during lifting-thrusting and twisting-rotating movements. Results: The force magnitude was significantly altered between needle diameters during lifting-thrusting movements, as shown by a significant positive correlation between needle diameter and force magnitude. In contrast, there was no difference in force magnitude with different needle diameters during twisting-rotating movements. Conclusion: Needle diameter can significantly affect stimuli and force magnitude dependent upon the type of manipulation. Research into the effect of other needle type characteristics and stimulation method is necessary to fully elucidate the role of acupuncture needle choice in treatment efficacy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.333-341
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• 2009

In this paper arc behavior in spiral type vacuum interrupter(VI) was analyzed by means of arc images, arc voltages and finite element method(FEM). As a result of experiment, the difference of arc voltage was observed under different twisting angles. It was found that the reason of the difference was the difference of arc resistance from simultaneous analysis of arc images and arc voltages. and the difference of arc resistance was explained by Lorentz force calculation with FEM. And the results of calculation were sufficient to explain the experimental results.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.75-83
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• 2001

The characteristics of structural behavior for a cable dome shows a strong nonlinearity and very sensitive by the initial imperfection. The instability phenomenon of Geiger-type cable dome structure is generated due to the in-plane twisting near the critical load level. In this study, therefore, the effect of bracing reinforcement resisting to the in-plane twisting is investigated for the Geiger-type model reinforced by bracing. The effect of initial imperfection is also studied because the structural instability phenomenon of shell-like structure is very sensitive according to the initial condition.

• Textile Coloration and Finishing
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• v.16 no.1
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• pp.1-4
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• 2004

This research surveys the twisting and untwisting tensions according to the various processing conditions of belt type texturing such as draw ratio, 1st heater temperature and velocity ratio. The 1st heater temperature was changed from 1606{\circ}C\; to\; 220^{\circ}C$, draw ratio was changed from 1.6 to 1.9 and velocity ratio was changed from 1.4 to 1.8. The twisting and untwisting tensions are measured with the variation of these processing conditions, in addition, the untwisting tension(T2) and tension ratio(T2/Tl) according to the various processing conditions are analysed with the false twist mechanism which is affected to the physical properties of draw textured yams.

• Journal of Biomedical Engineering Research
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• v.31 no.1
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• pp.56-66
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• 2010

The various total replacement artificial discs have developed because spinal fusion has shown a lesser mobility of an operated segment and an accelerated degeneration at adjacent discs. But almost artificial discs have not yet been reached on the substitute surgery of fusion because many problems such as those clinical success rates were not more than them of fusion have not solved. In this paper, vertically inserted assemble-screw fixture in vertebrae was proposed to improve the fixed capability of artificial disc. And also, to evaluate the design suitability of newly designed screw-type, including fixtures of commercial discs such as wedge and plate type, the 1/4 finite element model with a vertebra and various implanted fixtures were generated, and next, 3 bending motions such as flexion, bending and twisting under the moment of 10Nm and compression under the force of 1000N were considered, respectively and finally, FE analyses were performed. Results of three fixture types were compared, such as Range of Motion and maximal stress, and so on. For ROM, the screw type was average 58% less than the wedge type and was average 42% less than the plate type under all loading conditions. For average stress ratio at closer nodes between vertebra and each fixture, the wedge type was the lowest as minimum 0.02 in twisting, screw types were the highest as maximum 0.28 in compression. As the results of using cement material, it was predicted that the instability problem of the wedge type was better solved. The screw type which could be increased by implanting depth according to the number of assembling mid screws, showed that the decreased tendency of ROMs and maximal cancellous bone stresses. In further study, controlling the number of assembling screws that was suitable for a patient's bone quality, development of surgical tools and keeping on design supplementations, which will be able to develop the competitive artificial disc.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.165-175
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• 1996

the process of strip twisting is practiced for the manufacture of some commercial parts such as elements for tube type line mixers. A thin metal strip with rectangular cross section is twisted thru an angle greater than 180。. Initial geometry is altered in to a complex one with dimen-sional changes. In practice several tryouts are necessary to obtain required dimensional accu-racies. A simple analysis model is proposed to predict the dimensional changes forming torque and axial force.