• 소성∙가공
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• 제27권1호
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• pp.37-47
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• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• The Korean Journal of Physiology and Pharmacology
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• 제21권4호
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• pp.371-376
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• 2017

The caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn; MDH) receives direct inputs from small diameter primary afferent fibers that predominantly transmit nociceptive information in the orofacial region. Recent studies indicate that reactive oxygen species (ROS) is involved in persistent pain, primarily through spinal mechanisms. In this study, we aimed to investigate the role of xanthine/xanthine oxidase (X/XO) system, a known generator of superoxide anion ($O_2{^-}$), on membrane excitability in the rat MDH neurons. For this, we used patch clamp recording and confocal imaging. An application of X/XO ($300{\mu}M/30mU$) induced membrane depolarization and inward currents. When slices were pretreated with ROS scavengers, such as phenyl N-tert-butylnitrone (PBN), superoxide dismutase (SOD), and catalase, X/XO-induced responses decreased. Fluorescence intensity in the DCF-DA and DHE-loaded MDH cells increased on the application of X/XO. An anion channel blocker, 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS), significantly decreased X/XO-induced depolarization. X/XO elicited an inward current associated with a linear current-voltage relationship that reversed near -40 mV. X/XO-induced depolarization reduced in the presence of $La^{3+}$, a nonselective cation channel (NSCC) blocker, and by lowering the external sodium concentration, indicating that membrane depolarization and inward current are induced by influx of $Na^+$ ions. In conclusion, X/XO-induced ROS modulate the membrane excitability of MDH neurons, which was related to the activation of NSCC.

• Smart Structures and Systems
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• 제26권5호
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• pp.619-629
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• 2020

Solar towers, which often has a large aspect ratio and low fundamental natural frequency, were extremely prone to large amplitude of wind-induced vibrations, especially Vortex-Induced Vibration (VIV). A tiny Tuned Mass Damper (TMD) with conveniently adjustable eddy current damping was specially designed and manufactured for elastic wind tunnel tests of a solar tower. A series of numerical simulations by using the COMSOL software were conducted to determine three key parameters, including the thickness of the back iron plate and the conductive plate (T_b and T_c), the distance between the magnet and the conductive plate (T_d). Based on the results of numerical simulations, a tiny TMD was manufactured and its structural parameters were experimentally identified. The optimized values of the tiny TMD can be conveniently realized. The tiny TMD was installed at the top of the elastic test model of a 243-meter-high solar tower, and a series of wind tunnel tests were carried out to examine the effectiveness of the TMD in suppressing wind-induced responses of the test model. The results showed that the wind-induced responses could be obviously reduced by the TMD, especially in the cross-wind direction. The cross-wind RMS and peak responses at the critical wind velocity can be reduced by about 86% and 75%, respectively. However, the maximum reduction of the responses at the design wind velocity is about 45%, obviously less than that at the critical wind velocity.

• 한국태양광발전학회지
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• 제4권2호
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• pp.14-24
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• 2018

The potential induced degradation (PID) phenomenon of crystalline silicon photovoltaic (PV) modules has been often found in outdoor PV systems until recently since firstly reported in 2010. Many studies have been conducted about the mechanism and the preventive methods, but systematic diagnosis of the PID has not been applied on-site. This paper focuses on analysis of 5 categories and 10 PID diagnosis methods using the monitoring data, light current-voltage, dark current-voltage, infrared and electroluminescence. We expect to contribute to improvement of power generation through PID diagnosis and troubleshooting in PV plants.

• Journal of Information Display
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• 제6권3호
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• pp.6-11
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• 2005

In this paper, a general performance of the PSS-LCD or Polarization Shielded Smectic Liquid Crystal Display is discussed. This smectic base LCD does not use any spontaneous polarization, but uses induced polarization just sa me with current nematic base LCDs. Specific initial molecular alignment as well as specific cell design realizes ext remely fast optical response speed with native wide viewing angle. Moreover, this performance is provided by full compatible electronics for current conventional LCDs. A general performance of the PSS-LCD is introduced herein.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.132-137
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• 1995

Numerical analysis is conducted on the deformation of free surface of magnetic fluid. Steady magnetic fields are induced by a circular current loop. Governing equations of magnetic fields are solved by using the concept of vector potential. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. The deformations of free surface of magnetic fluid are qualitatively clarified. And, the patterns of steady non-uniform magnetic fields induced by a circular current loop are quantitatively presented.

• ETRI Journal
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• 제35권6호
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• pp.1164-1167
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• 2013

We correlate the failure in miniature X-ray tubes with the field emission gate leakage current of gated carbon nanotube emitters. The miniature X-ray tube, even with a small gate leakage current, exhibits an induced voltage on the gate electrode by the anode bias voltage, resulting in a very unstable operation and finally a failure. The induced gate voltage is apparently caused by charging at the insulating spacer of the miniature X-ray tube through the gate leakage current of the field emission. The gate leakage current could be a criterion for the successful fabrication of miniature X-ray tubes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1265-1270
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• 2008

Electromigration is a one of a critical failure mechanism in microelectronic devices. Minimizing the thin film interconnections in microelectronic devices make high current densities at electrrical line. Under high current densities, an electromigration becomes critical problems in a microelectronic device. This phenomena under DC conditions was investigated with high temperature. The current density of 1.5MA/cm2 was stressed in interconnections under DC condition, and temperature condition $150^{\circ}C,\;175^{\circ}C,\;200^{\circ}C$. By increasing of thin film interconections, microelectronic devices durability is decreased and it gets more restriction by temperature. Electromigration makes electronic open by void induced, and hillock induced makes electronic short state.

• Journal of Magnetics
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• 제12권1호
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• pp.1-6
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• 2007

The spin transfer torque generated by a spin-polarized current can induce the shift of the magnetic domain-wall position. In this work, we study theoretically the current-induced domain-wall motion by using the collective coordinate approach [Gen Tatara and Hiroshi Kohno, Phys. Rev. Lett. 92, 86601 (2004)]. The approach is extended to include not only the domain-wall position and the polarization angle changes but also the domain-wall width variation. It is demonstrated that the width variation affects the critical current.

• Corrosion Science and Technology
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• 제12권6호
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• pp.288-294
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• 2013

When the automotive body enters an electrocoating tank while applying an electric current, its steel surface is exposed to a very low induced current. Consequently, surface defects of coating may arise if the steel surface has lack of electric uniformity due to local defects such as local oxide. In this study, we investigated the preceding assessment methods to evaluate steel susceptibility of the low induced current during electrocoating before mass production. Prior to general electrocoating, we applied low constant voltage such as 3V or low constant current densities such as $0.35mA/cm^2$ and $0.50mA/cm^2$. In result, we confirmed that such methods were efficient for assessing steel susceptibility of low induce current during electrocoating.