• Journal of the Korean Society for Heat Treatment
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• v.23 no.5
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• pp.239-244
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• 2010

Influence of Zr addition on grain stability at elevated temperatures has been investigated for extruded pure Mg and Mg-0.25%Zr alloy. The grain size of pure Mg increases rapidly with increasing annealing temperature when isochronally annealed for 60 min from 573 to 773 K, whereas the grains are stable up to 723 K for the Zr-containing alloy. The activation energies for grain growth ($E_g$) at this temperature range were determined as 75.3 and 105.9 kJ/mole for the pure Mg and Mg-0.25%Zr alloy, respectively. TEM observations on the annealed Mg-Zr samples revealed that higher thermal stability and higher activation energy for grain growth resulting from Zr addition in Mg may well be associated with the restriction of grain growth by nano-sized Zr particles distributed in the microstructure.

• Advances in Energy Research
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• v.3 no.1
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• pp.1-10
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• 2015

In the past sidetracking was the means to bypass a damaged zone or to correct the direction of a wellbore. Nowadays, this method is very common and useful in relocating the bottom of a wellbore in a more productive zone and consequently enhancing the production of a reservoir by saving a significant amount of time and money. In this paper, the stability of the bend area is assessed considering varied conditions of stress regime and sidetrack orientation. In general, the stress regime and the orientation of the principal stresses have negligible effect on the stability of the sidetrack compared to sidetrack inclination. On the other hand, the sidetrack deviation angle from the vertical main well plays the major role in the stability of the bend area.

• Journal of Forest and Environmental Science
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• v.26 no.1
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• pp.31-36
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• 2010

Sixteen microsatellite markers (simple sequence repeat (SSR) markers) were employed to examine the genetic stability of 27 randomly chosen date palm (Phoenix dactylifera L.) plants produced through somatic embryogenesis with upto forty two in vitro subcultures. No microsatellite DNA variation was observed among all micropropagated plants. Our results indicate that the micropropagation protocol used for rapid in vitro multiplication is appropriate and suitable for clonal propagation of date palm and corroborated that somatic embryogenesis can also be used as one of the safe modes for production of true-to-type plants of date palm. This is the first report on the use of microsatellite DNA markers to establish the genetic stability in micropropagated date palm plants.

• Food Science and Preservation
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• v.11 no.2
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• pp.227-232
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• 2004

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.53.1-53.1
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• 2007

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• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.197-200
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• 1996

This paper considers feedback error learning neural networks for robot manipulator control. Feedback error learning proposed by Kawato [2,3,5] is a useful learning control scheme, if nonlinear subsystems (or basis functions) consisting of the robot dynamic equation are known exactly. However, in practice, unmodeled uncertainties and disturbances deteriorate the control performance. Hence, we presents a robust feedback error learning scheme which add robustifying control signal to overcome such effects. After the learning rule is derived, the stability is analyzed using Lyapunov method.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1705-1708
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• 2006

Nanocrystalline silicon (nc-Si) based TFTs were developed using a conventional PECVD production system. Devices exhibit very interesting characteristics, in particular when using a bi-layer structure which reduces leakage current and improves subthreshold area. Good stability and low leakage current make these devices suitable for the fabrication of low-cost and high performance AMOLED displays.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.481-483
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• 1998

The problem of production of new materials based on polyheteroarylenes and other polymers combining good mechanical and dielectric properties. radiation and chemical stability with heat- and thermal stability is related with the development of efficient synthesis technique of starting low-molecular compounds. Alicyclic dianhydrides are believed to be the promising monomers to synthesize various polymers.

• Journal of Plant Biology
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• v.36 no.4
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• pp.313-319
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• 1993

Photoproduction of hydrogen by free and polyvinylalcohol (PVA)-immobilized spinach chloroplasts was investigated. Immobilization of chloroplast with PVA increased the functional stability of the chloroplast during storage. PVA-immobilized chloroplasts preserved photosynthetic electron transport activity much better than free chloroplasts. The hydrogen production of free chloroplast decreased to 17% of initial activity after storage of six days. The hydrogen production of the PVA-immobilized chloroplast, however, showed 44% of initial activity after storage of 15 days. The maximal rate of hydrogen production was accomplished at 2$^{\circ}C$ under the light intensity above 116 $\mu$E.m-2.s-1. The amount of hydrogen produced was proportional to the chlorophyll concentration. The hydrogen production was inhibited by DCMU treatment, indicating hydrogen production is dependent on photosynthetic electron transport. These results suggest that PVA is a good candidate for the immobilization matrix of chloroplasts for the photoproduction of hydrogen.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1250-1256
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• 2011

In this study, Bacillus licheniformis cells were immobilized by entrapment in calcium alginate beads and were used for production of alkaline protease by repeated batch process. In order to increase the stability of the beads, the immobilization procedure was optimized by statistical full factorial method, by which three factors including alginate type, calcium chloride concentration, and agitation speed were studied. Optimization of the enzyme production medium, by the Taguchi method, was also studied. The obtained results showed that optimization of the cell immobilization procedure and medium constituents significantly enhanced the production of alkaline protease. In comparison with the free-cell culture in pre-optimized medium, about 7.3-fold higher productivity was resulted after optimization of the overall procedure. Repeated batch mode of operation, using optimized conditions, resulted in continuous production of the alkaline protease for 13 batches in 19 days.