• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.106-109
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• 2016

The YBaCuO superconducting bulks were prepared by the thermal diffusion process involving the peritectic reaction to investigate the effect on microstructure and superconductivity. All the diffused YBaCuO could be successively separated from superconducting 123 phase by applying the thermal diffusion process. Electromagnetic properties of treated and untreated YBaCuO superconductor were evaluated to investigate the pinning effect. It was confirmed experimentally that a large amount of magnetic flux was trapped in the thermal treated superconducting bulk than that in the untreated one, indicating that the pinning centers of magnetic flux are related closely to the occurrence mechanism of the magnetic effect.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.213-216
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• 2005

Salt attack and freezing & thawing test, one of the combined deterioration tests was performed to explore the mechanism of concrete structure deterioration under marine environment. Simple submerging test was proceeded to draw out its diffusion factor with salt water at the same time. Some of the mechanisms were driven with using three types of cements and four kinds of salt water concentrations. $\circ$ TBC was more durable than OPC or SRC for freezing and thawing action $\circ$ The higher chloride concentration of salt water was, the faster relative dynamic elastic modulus decreased and the higher the loss of weight was. $\circ$ The diffusion factor of TBC was smaller than those of TBC or SRC at simple submergence of concrete specimens into salt water.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.426-431
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• 1996

It is well known that the understanding of the complex mechanism of magnetoplasma is closely related with understanding of the collective behavior of discharge plasma parameters such as the cathode-sheath potential, cathode-sheath thickness, electron temperature, electron density, and ambipolar diffusion. In this paper, some of the relationships between these plasma parameters and magnetic field is investigated experimentally with a Langmuir probe in the magnetoplasma generated by D.C diode system. It is found that when magnetic field is increased, cathode-sheath potential, cathode-sheath thickness, and ambipolar diffusion are decreased. In addition, peak ion density obtained as a parameter of ionic signal voltage by Faraday cup method is independent of magnetic field. (author). 9 refs., 11 figs.,1 tab.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.128-131
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• 2004

The composite mesoporous ceramic membranes were prepared with ${\gamma}$-alumina and poly (2, 6-dimethyl-l, 4-pyphenylene oxide) (PPO) on the surface of the macroporous $\alpha$-alumina ceramic membranes and the permeation results were compared with those of the $\alpha$-alumina membrane for large-scale applications. In the results of the transport experiments, the ceramic membranes gave high gas permeances mainly due to Knudsen diffusion and surface diffusion as an additional mechanism. And, the polymer modification increased the permeances of the strongly adsorbing gas components. In this study the modifications of alumina ceramic membranes could increase the gas permeation performances especially for the strongly absorbing gas components.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.795-801
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• 1994

The BiPbSrCaCuO superconductor was fabricated by diffusion of The dual layer composed of SrS12TCaS11TCuS12TOS1xT in upper layer and BiS12TPbSI0.3TCuS12TOS1yT in lower layer, and varified growh-mechanism of BiPbSrCaCuO superconducting phase. And, we produced optimum conditions of spread volume and each stage of sintering time were upper layer:Lower layer=1:0.2, 1:0.4, 1:0.6 and 24hr., 120hr., 210hr. From the result, the optimum conditions are spread volume(Upper layer:Lower layer=1:0.6), sintering time(210hrs.) at 820$^{\circ}C$.The BiPbSrCaCuO superconductor, fabricated optimum condition, showed zero resistance at critical temperature of 70k.

• Journal of Pharmaceutical Investigation
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• v.29 no.3
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• pp.185-191
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• 1999

The polymeric films containing drug and various excipients were fabricated using aqueous-based $Eudragit^{\circledR}$ RS 30D dispersions. The diffusional behaviors and mechanism of the fabricated polymeric film were investigated using Keshary-Chien diffusion cell. The melatonin was used as a model drug. The diffusion behaviors of drug through the fabricated polymeric films were highly dependent on drug concentration in donor part, polymer contents and drug concentration, and the types of plasticizers and solubilizers. The fabricated polymeric films containing excipients and solubilizers could be applied for the controlled release of poorly water-soluble drug and for the preparation of drug-containing latex films for topical or oral drug delivery.

• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.21-25
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• 2009

Extinguishing limits of laminar ethylene/oxygen flames in both normal and inverse co-flow jet burner have been determined experimentally and computationally. An inert gas($N_2$, Ar, $CO_2$) was added into the oxidizer to find the critical concentration and the effectiveness of the agents on flame extinction. The experimental results showed that the physical aspect of inert gases was main mechanism for flame blow-out as same as cup burner test, but the flow effect should be considered to determine the extinction concentration. The numerical prediction was performed with modified WSR model and the result was in good agreement with the measurements. The experimental and numerical methods could be used for the assessment of various flame suppression agents such as minimum extinguishing concentration.

• Solar Energy
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• v.7 no.1
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• pp.35-41
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• 1987

This paper presents a comprehensive computer simulation of hydrogenated amorphous p-i-n silicon solar cells. The physical mechanism governing solar cell operation has been modeled and solved numerically by Runge-Kutta-Gill method. Effects of gap state density, dopant impurity, diffusion length and interface recombination velocity on solar cell performance are investigated. Numerical results show that the electric field in i-region is not uniform but depends strongly on voltage and position. A rather poor fill factor may be due to the electric field variation and short diffusion length. It is found out that the life time should be improved in order to increase a fill factor and a conversion efficiency.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.32-35
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• 1999

Poly(arylene ether phosphin oxide) (PEPO), Udel$^{\circledR}$ P-1700, Ultem$^{\circledR}$ 1000. poly(hydroxy ether) (PHE), carboxy modified poly(hydroxy ether)(C-PHE) and poly(hydroxy ether ethanol amine) (PHEA) were utilized for a coating of carbon fibers. Interfacial shear strength(IFSS) of polymers to carbon fibers was also evaluated in order to understand the adhesion mechanism. IFSS was measured via micro-droplet tests, and failure surfaces were analyzed by SEM. Diffusion between polymer and vinyl ester resin was investigated as a function of styrene content; 33. 40 or 50wt.% and the solubility parameters of polymers were calculated. The results were correlated to the interfacial shear strength. The highly enhanced interfacial shear strength (IFSS) was obtained with PEPO coating, and marginally improved IFSS with PHE, Udel$^{\circledR}$ and C-PHE coatings, but no improvement with PHEA and Ultem$^{\circledR}$ coatings.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.60-64
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• 2009

We investigated an operating characteristic of linear-type magnetic flux pump (LTMFP) as a current compensator under the various conditions. In order to explain the mechanism of the LTMFP, the magnetic behavior of superconducting Nb foil according to pumping actions should be understood. In this paper, the magnetic field analysis of superconducting Nb foil installed in LTMFP has been performed based on the three-dimensional finite element method (3D FEM). Through the simulation analysis, the normal spot region on the superconducting Nb foil is found to be enhanced swiftly over about 20 Hz. The simulated finding agreed with an analytical estimation based on the phenomenon of magnetic diffusion.