• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1870-1875
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• 2003

Optimization has been used in many engineering problems and must be one of the essential components during design process now. It is the process of maximizing the performance called an objective function of a system while satisfying some constraints, so finite element method is generally required in order to obtain these values during optimization. However, there are some difficulties to obtain them by means of FEM, where the changes of design variables cause the distortion and the regeneration of mesh that may result in inaccuracy and inefficiency. In order to overcome this problem, this paper proposed an alternative that the eXtended FEM introduced and developed by Ted Belytschko was applied to the optimization process because the key points of the X-FEM lie in that the discontinuity can be represented independently on the mesh by a function called in an enrichment function.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1571-1576
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• 2010

Two bacterial strains designated as CT2 and CT5 were isolated from highly alkaline cement samples using the enrichment culture technique. On the basis of various physiological tests and 16S rRNA sequence analysis, the bacteria were identified as Bacillus species. The urease production was 575.87 U/ml and 670.71 U/ml for CT2 and CT5, respectively. Calcite constituted 27.6% and 31% of the total weight of sand samples plugged by CT2 and CT5, respectively. Scanning electron micrography analysis revealed the direct involvement of these isolates in calcite precipitation. This is the first report of the isolation and identification of Bacillus species from cement. Based on the ability of these bacteria to tolerate the extreme environment of cement, they have potential to be used in remediating the cracks and fissures in various building or concrete structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1194-1200
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• 1991

The FEM is a computer-aided mathematical technique for obtaining approximate solution to the differential equations. The pointwise convergence defines the relationship between the mesh size and the tolerance. This will play an important role in improving quality of finite element approximate solution. In the paper. We evaluate the convergence on a certain unknown point with a 1-irregular mesh refinement and spectral order enrichment. This means that the degree of freedom is minimized within a tolerance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.112-119
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• 2002

In this paper, an Extended Finite Element Method is proposed by adding discontinuity and singularity enrichment functions to the standard FEM approximation. In this method, the singularity and the discontinuity of the crack are efficiently modeled by using initial regular mesh without refining mesh near the crack tip, so that it enables express the asymptotic stress field near crack tip and crack surface successfully. The developed method was verified by evaluating crack tip stress profile and stress intensity factor of mode Ⅰ/mode Ⅱ fracture problems and the results showed the effectiveness and robustness for fracture problem.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.335-342
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• 2001

In this paper, an improved Element-Free Galerkin (EFG) method is proposed by adding enrichment function to the standard EFG approximation and a discontinuity function is implemented in constructing the shape function across the crack surface. In this method, the singularity and the discontinuity of the crack are efficiently modeled by using initial node distribution to evaluate reliable stress intensity factor, though the standard EFG method requires placing additional nodes near the crack tip. The proposed method enables the initial node distribution to be kept without any additional nodal d.o.f. and expresses the asymptotic stress field near the crack tip successfully. Numerical example verifies the improvement and the effectiveness of the method.

• Korean Membrane Journal
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• v.1 no.1
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• pp.73-80
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• 1999

The removal of trace chlorinated and aromatic hydrocarbons from water by a pervaporation technique has been carried out through poly (dimethylsiloxane) membrane which had been fabricated by the addition crosslinking reaction. This study dealt with the swelling and permeation behaviors of the PDMS membranes with dichloroethane trichloroethane and toluene aqueous solutions. The swelling ratio in the toluene aqueous solution was much higher than those in the chloroethane solutions at all of the operating temperatures and concentrations. The solubility parameter theory was introduced to interpret the affinity between permeates and a membrane material and in all cases this approach seemed to be proper. It was suggested that the existence of water clusters in the membrane due to the hydrophobic characteristics of the membrane made the size of the permeating water larger resulting in suppressing water permeation and increasing enrichment of the organic components. The permeation behaviors at different membrane thicknesses were indirectly interpreted in terms of the effect of concentration polarization.

• Korean Journal of Microbiology
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• v.21 no.4
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• pp.185-190
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• 1983

Twelve Microorganisms capable of utilizing diaminododecane were isolated from the soil by enrichment culture technique. Seven strains of these were identified as Corynebacterium. The isolated strains were tested for the ability to utilize as carbon source, 10 different kind of alkane derivatives containing CN, $NH_2$, Cl, and SH groups. Laurylcyanide, dicyanooetane, chlorodecane, and dichlorodecane were not utilized by any of the isolated strains; putrescine dihydrochloride, cadaverine dihydrochloride, diaminododecane, and n-dodecane were utilized by all of the isolated strains; and all of the isolated strains except DAD 2-3 could utilize dodecylmercaptan. The alkane derivatives that did not serve as ,growth substrates were tested further in oxidation tests using resting cell preparation. Alkane derivatives that are being oxidized by all of the isolated strains are laurylcyanide and dichlorodecane. Dicyanooctane was also oxidized by all of the isolated strains except DAD 30L, chlorodecane was the only oxidized by the three isolated strains. The most remarkable substrate that is being oxidized is dichlorodecane containing CN groups diterminally. Evidence obtained with thin layer chromatography of ,ethyl acetate extracts of culture broth of isolated strains grown in some alkane derivatives shows that these alkane derivatives are degraded.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.570-574
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• 2001

Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 bonded Merrifield peptide resin using an elution chromatographic technique. The capacity of the novel azacrown ion exchanger was 1.0 meq/g dry resin. The heavier isotopes of magnesium were enriched in the resin phase, while the lighter isotopes were enriched in the solution phase. The single stage separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assys. The separation factors of $^{24}Mg^{2+}$-$^{25}Mg^{2+}$, $^{24}Mg^{2+}$-$^{26}Mg^{2+}$, and $^{25}Mg^{2+}$-$^{26}Mg^{2+}$ were 1.008, 1.019, and 1.006, respectively.

• Fashion & Textile Research Journal
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• v.5 no.1
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• pp.17-24
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• 2003

Objet, which showed up with the art of 20C, is now an important element giving a creative idea to fashion designers in modern times. The purpose of the study is to review how the objet technique was paid attention and recreated in the fashion, through the analysis of works, and the formative features of each technique for fashion, in order to identify the connection of arts and fashion, and the position of fashion as art. The techniques using object appeared in the 20th century fashion are as follows: First, papier-colle, which is adding printed materials onto the surface, is such a technique that adds cut-feeling materials to impose a new texture, or arrange again the cloth-cuts to create a different clothing from the existing one, which went to the extension of materials in the fashion. Second, collage of daily materials expresses directly and emotionally through direct presentation of the objets. Especially, collage of patch-work is reproduced into a new fabric depending on the objet used, giving a standing over the form. Third, ready-made which presents the material meaning only of the objet expands the range of objets which could be used in the fashion by introducing the daily materials having a meaning itself as a fashion. Forth, an attempt to approach to the objets of popular image by designed techniques come out in modern fashion as a graffiti look or a typography look, making the clothing itself an objet to transmit a message directly to the masses. Introduction of various objets and development of expression technique brought out the diversification of materials, and enrichment and extension of expression sphere, which resultingly spreaded the freedom of expression and progressed into the art sphere, making a direct motif to solidify its standing as a formative art.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.304-311
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• 2012

Chlorinated ethylenes such as perchloroethylene (PCE) and trichloroethylene (TCE) are widely used as industrial solvents and degreasing agents. Because of improper handling, these highly toxic chlorinated ethylenes have been often detected from contaminated soils and groundwater. Biological PCE dechlorination activities were tested in bacterial cultures inoculated with 10 different environmental samples from sediments, sludges, soils, and groundwater. Of these, the sediment using culture (SE 2) was selected and used for establishing an efficient PCE dechlorinating enrichment culture since it showed the highest activity of dechlorination. The cathode chamber of bioelectrochemical system (BES) was inoculated with the enrichment culture and the system with a cathode polarized at -500 mV (Vs Ag/AgCl) was operated under fed-batch mode. PCE was dechlorinated to ethylene via TCE, cis-dichloroethylene, and vinyl chloride. Microbial community analysis with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) showed that the microbial community in the enrichment culture was significantly changed during the bio-electrochemical PCE dechlorination in the BES. The communities of suspended-growth bacteria and attached-growth bacteria on the cathode surface are also quite different from each other, indicating that there were some differences in their mechanisms receiving electrons from electrode for PCE dechlorination. Further detailed research to investigate electron transfer mechanism would make the bioelctrochemical dechlorination technique greatly useful for bioremediation of soil and groundwater contaminated with chlorinated ethylenes.