• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.89-90
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.222-226
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• 1992

In this study, the technique of adaptive control based on certainty equibalence for input-output linerization of nonlinear system is investigated. It is shown that the upper bound of the parameter estimation error can be represented more explicitly than Teel et al's works. Another direct approach, which shows that the adaptive input-output linearing control laws using the normalized identifier yield bounded tracking is also presented.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.42-42
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• 1997

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.206-207
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• 2001

The photorefractive (PR) effect in liquid crystals sandwiched between photoconductive polymer layers was first studied by Ono et al. They reported that the PR effect vanished at steady state If there were not insulating layers because no charge trapping occurred in the photoconductive poly(N-vinylcarbazole) (PVK) layers. However we observed a significant PR effect in the polymer layered liquid crystal (PLLC) system where a liquid crystal layer doped with fullerene is sandwiched between two photoconductive PVK layers. (omitted)

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.67
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• pp.61-68
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• 2001

A study to analyze and solve problems of multi wire installation duct experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through ana1ysis of the experimental results using S/N ratio.

• The Korean Journal of Pharmacology
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• v.12 no.1
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• pp.15-22
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• 1976

The clinical abuse of C.N.S. stimulants during recent years has directed particular attention. Effect of various organs other than C.N.S. was also extensively investigated with those agents. It has been shown that, although there is a wide variation in sensitivity between species, caffeine stimulates gastric secretion in man, cat, guinea pig and dog. Roth and Ivy(1944) reported that caffeine and histamine acted synergistically in stimulating gastric secretion in the cat. Vaille et al(1966) studied that production of pancreatic juice in the rat was enhanced, but bile secretion was not affected by caffeine. In clinical study the effect of chlorpromazine on the external pancreatic secretion in the 24 subjects, the volume fell more than 20% in 7 subjects. (Skajaa et al 1960) It is widely known that C.N.S. stimulants enhanced spontaneous motor activity in the mice, while tranquilizers depressed the activity. Woo (1975) reported that the group of mice treated with chlorpromazine showed markedly inhibited motor activity and in the group of mice treated with amphetamine, there was a significant increase in the motor activity. The purpose of the present experiment was to study the effects of C.N.S. stimulants and depressant on the exocrine pancreas, and on the spontaneous motor activity in the rats. The results obtained are summarized as follows. 1. In animals treated with xanthine derivatives, the volume of pancreatobiliary secretion was markedly increased. 2. Total bilirubin output was elevated markedly in the xanthine derivatives and imipramine treated animals. The bilirubin concentration was increased in xanthine derivatives treated group. 3. The concentration of cholate in the bile was decreased in the chlorpromazine treated group. 4. The activity of lipase in the pancreatobiliary juice was elevated markedly in the xanthine derivatives treated group only. 5. In the all experimental groups, the activity of amylase in pancreatobiliary juice was significantly elevated. 6. In the caffeine treated group, spontaneous motor activity was markedly increased in $30{\sim}60$ minutes, and the amphetamine treated group showed the increased motor activity in first 30 minutes. 7. The group of rats treated with chlorpromazine showed markedly inhibited motor activity after 30 minutes, and the imipramine treated group showed similar result but less inhibition.

• Journal of the Korean Vacuum Society
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• v.11 no.1
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• pp.35-42
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• 2002

We fabricate thermally stable and low resistance Ru ohmic contacts to $n-ZnO:Al(3\times10^{18}\textrm{cm}^{-3})$, grown by specially designed dual target sputtering system. It is shown that the as-deposited Ru contact produces a specific contact resistance of $2.1{\times}10^{-3}{\Omega}\textrm{cm}^2$. Annealing of the Ru contacts leads to the improvement of current-voltage characteristics. For example, annealing of the contact at $700^{\circ}C$ for 1 min produces a contact resistance of $3.2{\times}10^{-5}}{\Omega}\textrm{cm}^2$. furthermore, the metallisation scheme is found to be thermally stable: the surface of the contact is fairly smooth with a rms roughness of 1.4 nm upon annealing at $700^{\circ}C$. These results strongly indicate that the Ru contact represents a suitable metallisation scheme for fabrication of high-performance ZnO-based optical devices and high-temperature devices. In addition, possible mechanisms are suggested to describe the annealing temperature dependence of the specific contact resistance.

• International Journal of Concrete Structures and Materials
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• v.8 no.3
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• pp.213-228
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• 2014

Alkali-activated binder (AAB) is recently being considered as a sustainable alternative to portland cement (PC) due to its low carbon dioxide emission and diversion of industrial wastes and by-products such as fly ash and slag from landfills. In order to comprehend the behavior of AAB, detailed knowledge on relations between microstructure and mechanical properties are important. To address the issue, a new approach to characterize hardened pastes of AAB containing fly ash as well as those containing fly ash and slag was adopted using scanning electron microscopy (SEM) and energy dispersive X-ray spectra microanalyses. The volume stoichiometries of the alkali activation reactions were used to estimate the quantities of the sodium aluminosilicate (N-A-S-H) and calcium silicate hydrate (CSH) produced by these reactions. The 3D plots of Si/Al, Na/Al and Ca/Si atom ratios given by the microanalyses were compared with the estimated quantities of CSH(S) to successfully determine the unique chemical compositions of the N-A-S-H and CSH(S) for ten different AAB at three different curing temperatures using a constrained nonlinear least squares optimization formulation by general algebraic modeling system. The results show that the theoretical and experimental quantities of N-A-S-H and CSH(S) were in close agreement with each other. The $R^2$ values were 0.99 for both alkali-activated fly ash and alkali-activated slag binders.

• Journal of IKEEE
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• v.26 no.4
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• pp.633-638
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• 2022

Rencently, neuromorphic systems of spiking neural networks (SNNs) that imitate the human brain have attracted attention. Neuromorphic technology has the advantage of high speed and low power consumption in cognitive applications and processing. Resistive random-access memory (RRAM) for SNNs are the most efficient structure for parallel calculation and perform the gradual switching operation of spike-timing-dependent plasticity (STDP). RRAM as synaptic device operation has low-power processing and expresses various memory states. However, the integration of RRAM device causes high switching voltage and current, resulting in high power consumption. To reduce the operation voltage of the RRAM, it is important to develop new materials of the switching layer and metal electrode. This study suggested a optimized new structure that is the Metal/Al₂O₃/HfO_x/SWCNTs/N+silicon (MOCS) with single-walled carbon nanotubes (SWCNTs), which have excellent electrical and mechanical properties in order to lower the switching voltage. Therefore, we show an improvement in the gradual switching behavior and low-power I/V curve of SWCNTs-based memristors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.19-22
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• 1996

GaN films were prepared on Al$_2$O$_3$(1120) substrates by hydride vapor phase epitaxy (HVPE) with HCl-NH$_3$-N$_2$ gas system. The growth rate was increased with increasing the substrate temperature below 1050$^{\circ}C$ and decreased over the temperature, increased with growth time. The X-ray diffraction patterns showed only (0002) GaN peak. The UV-Visible Spectrophotometer showed a good optical absorption and fundamental absorption occurred at 3700${\AA}$.