• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.356-362
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• 2004

Using multi wrapped copper by polyimide film for HTS transformer, the breakdown and V-t characteristics of two type models for turn-to-turn, one is point contact model, the other is surface contact model, were investigated under ac and impulse voltage at 77 K. A material that is Polyimide film (Kapton) 0.025 mm thickness is used for multi wrapping of the electrode. Statistical analysis of the results using Weibull distribution to examine the wrapping number effects on V-t characteristics under at voltage as well as breakdown voltage under ac and impulse voltage in $LN_2$ was carried. Also, survival analysis was performed according to the Kaplan-Meier method. The breakdown voltages for surface contact model are lower than that of the point contact model, because the contact area of surface contact model is wider than that of point contact model. At the same time, the shape parameter of the point contact model is a little bit larger than the of the surface contact model. The time to breakdown tn is decreased as the applied voltage is increased, and the lifetime indices slightly are increased as the number of layers is increased. According to the increasing applied voltage and decreasing wrapping number, the survival probability is increased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.10a
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• pp.157-164
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• 1994

Finite element analysis of material deformation is successfully utilized to understand metal forming processes such as forging, extrusion and deep drawing. However, such analysis involves contact problems; a free node touches a die surface and a contact node slips along the die surface. In the present investigation, appropriate contact algorithms were developed assuming that a three dimensional surface can be divided into bilinear patches and that nodal velocities are linear during an incremental time. The algorithms were coded into a computer program and tested for a simple surface. Comparison of the test result with that obtained from a commercial code is presented and discussed.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.139-142
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• 1996

This paper presents a method of controlling contact force for deburring tasks. The cope with the nonlinearities and time-varying properties of the robot and the environment, a neural network control theory is applied to design the contact force control system. We show that the contact force between the hand and the contacting surface can be controlled by adjusting the command velocity of a robot hand, which is accomplished by the modeling of a robot and the environment as Mass-Spring-Damper system. Simulation results are shown.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.501-505
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• 1996

In CMM system, a contact probe is not applicable to very small, or flexible elements. There is need to develop non-contact probes of CCD camera. But non-contact probes have some technical problems, including distortion, user interface and time delay. This development gives the foundation of the non-contact probe system and some useful solutions for the problems. The results can be useful for industry application.

• Food Science and Preservation
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• v.20 no.6
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• pp.846-853
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• 2013

We investigated the effect of the cell-wall-degrading enzyme and its skin contact time on the brewing characteristics of Cheongsoo grape. The easy of juice extraction was excellent at the cell-wall-degrading enzyme and skin contact treatments, and the aroma was best after five days of skin contact treatment. Furthermore, the juice yields of the Chengsoo grape were more dramatically increased by the cell-wall-degrading enzyme and skin contact treatments than by the control. The data on the pH, total acidity, and soluble solids did not significantly differ among the treatments, and the pH range from 3.1 to 3.4; the total acidity from 0.5% to 0.6% (as tartaric acid); and the soluble solids, from 6.7 to 7.1 $^{\circ}Brix$. The alcohol content of cell-wall-degrading enzyme treatment was highest with 13.3%. The total polyphenol was gradually increased with the longer skin contact time, and was highest after 10 days of skin contact treatment, at 306.4 mg/L. The main organic acids detected in the Cheongsoo wine were malic and tartaric acid, and citric, succinic and lactic acid were also detected. Our results show that the cell-wall-degrading enzyme and skin contact treatments were better in terms of the easy of juice extraction and significantly increased the juice yield and the volatile compound of the Cheongsoo wine.

• Journal of Welding and Joining
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• v.32 no.6
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• pp.35-40
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• 2014

The contact tip for gas metal arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. If the contact tip is damaged, it is a cause of lowering the welding productivity due to removal of welding defects and replacement of contact tip. In case of the use of a contact tip for a long time the arc is unstable because the processed hole in the contact tip center is larger, and the variation of aiming position of the welding wire causes a seam tracking error. In this study, gas metal arc welding experiments using contact tip of three different materials were performed. The contact tips with Cu-P, Cu-Cr, and Cu-ODS were used at the experiments, and the welding characteristics by each contact tip were evaluated. After welding contact tip appearance, welding spatter adhesion amount of the nozzle, and weld bead appearance were evaluated. The welding current and welding voltage were measured to verify arc stability during arc welding.

• Progress in Superconductivity and Cryogenics
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• v.20 no.3
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• pp.15-20
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• 2018

No-insulation (NI) pancake magnets are fabricated using Rare earth-Barium-Copper Oxide (REBCO) coated conductor (CC) tapes, which enabled a very compact magnet in the aspects of high critical current density ($J_c$) and high mechanical strength by removing insulation and allowing thinner stabilizer. They have also advantages such as self-quench protection. Therefore, it does not need quench detection and protection that can be very challenging in a high critical temperature ($T_c$) superconducting magnet technology. Recently, it was reported that the NI REBCO CC magnets have some drawbacks of long charging time and high field ramp loss which will be a concern in the operation of cryocooled magnets. These issues are related to the turn-to-turn contact resistivity and can be released by managing it. This is also closely related to the activity of reducing the contact joint resistance in the case of CC joints for long length CC fabrication. Therefore, in this study, the turn-to-turn contact resistance ($R_c$) at the CC contact part of differently stabilized CC tapes was measured. The behaviors of $R_c$ at CC contact parts according to the applied contact pressure were investigated. The range of $R_c$ measured for CC tapes adopted will provide fundamental data for design and fabrication of the CC NI coils.

• Journal of Korean Academy of Nursing
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• v.35 no.5
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• pp.842-849
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• 2005

Purpose: The main purpose of this study was to establish a nursing intervention data base to improve maternal attachment. Method: The first group of mothers( control group), experienced their first physical contact with their infants after being discharged from the hospital. The second group (experimental group) practiced early initial mother-infant postpartum contact known as the most sensitive period for founding maternal-infancy attachment. The subjects of this study gave birth to normal infants at M hospital from Aug.25 to Sept.30, 2004. During the same time, data was collected through direct observation, with instruments designed by Cropley et al., to assess the behaviors of normal attachment. The statistical methods for data analysis were percentage, mean, standard deviation and t-test with an SPSS program. Result: The group practicing initial mother-infant contact, showed a higher degree of physical and functional bonding than the group experiencing the first contact after discharge from the :10spital (control group)(p<.0l). The group practicing initial mother-infant contact, showed higher degrees of bonding attachment assessments than the group experiencing their first initial contact after their discharge from the hospital(p<.01). Conclusion: The group practicing early mother-infant contact, showed more maternal-infant interaction than the group experiencing their initial contact after their discharge from the hospital. These results show that maternal attachment behavior increases according with an early initial mother-infant contact.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.1
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• pp.52-58
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• 2007

We propose a new contact detection algorithm for fine pitch wire bonding. Fast and stable contact detection of the z-axis in wire bonding is extremely important to maintain the quality of fine pitch gold wire bonding processes, which use a small pad less than $70{\mu}m$ in diameter. A small perturbation in the contact detection time causes a large difference in the size of the formed squashed ball. The new detection method is based on a statistical approach and designed for a discrete Kalman filter. It is faster and has smaller detection time variations than conventional detection methods. Experimental results are presented to demonstrate the advantages of the proposed algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1376-1391
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• 2015

In bus delay-tolerant networks, the route of bus is determinate but its arrival time is indeterminate. However, most conventional approaches predict future contact without considering its uncertainty, which makes a limitation on routing performance. A novel approach is proposed by employing interval algebra to characterize the contact's uncertainty and time-varying nature. The contact is predicted by using the Bayesian estimation to achieve a better routing performance. Simulation results show that this approach achieves a good balance between delivery latency and delivery ratio.