• KSBB Journal
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• v.13 no.4
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• pp.383-390
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• 1998

Bacillus subtilis DT134 was resistant to 50-fold higher concentration of cadmium ions (Cd2+) than cadmium-sensitive B. subtilis BD224 in Luria Broth (LB) medium. Minimal inhibition concentration test in LB agar plates also showed similar results. The elevated cadmium resistance of B. subtilis DT134 strongly suggested a possible existence of cadmium resistance gene in it. Southern blot with Staphylococcus aureus cadA gene fragment (757 bp NlaIV-XmnI cadA DNA fragment) as probe was carried out to test the existence and similarity of the gene. In high stringency condition, there was no detectable signal, but in low stringency, a strong signal specific to the cadA probe could be detected. These results strongly suggested that there was some similarity between total DNA of B. subtilis DT134 and S. aureus pl258 in terms of cadmium resistance gene and the resistance mechanism might be an efflux mechanism. The subsequent efflux experiment showed that the cadmium resistance mechanism of B. subtilis DT134 was also due to the efflux of cadmium.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.43-45
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• 2000

Resistance Spot Welding has been one of the important process in the sheet metal fabrication of auto-body industry It is well known that the nugget formation of RSW is the major factor for the strength of the body. A high speed camera was used to consider initial melting and growth of the weld nugget in order to find out the nugget formation mechanism. It was observed that such mechanism had an effect on the dynamic resistance, which was a process parameter of resistance spot welding. Also, the relationship between the mechanism and process parameter was considered for the industrial application.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.379-384
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• 1996

The H2S sensing mechanism of CuO-SnO2 was confirmed by analyzing the electrical-resistance variation with temperature under an H2S atmosphere. While the resistance of CuO-SnO2 thick film at N2+H2S atmosphere was almost invariant with change in temperature it increased with increasing temperature for air +H2S atmos-phere. This behavior was analyzed using an equation derived from a basic assumption based on the H2S sensing mechanism proposed before. the experimental results are sufficiently explained with the equation derived which showed that the H2S sensing mechanism was reasonable. The equation also gave a detailed analysis and physical meaning to the behavior of the resistance variation with change in H2S concentration.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3033-3038
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• 2012

The hydrogen storage mechanism of graphite was studied by measuring the electrical resistance change. Graphite was expanded and activated to allow for an easy hydrogen molecule approach and to enlarge the adsorption sites. A vanadium catalyst was simultaneously introduced on the graphite during the activation process. The hydrogen storage increased due to the effects of expansion, activation, and the catalyst. In addition, the electrical resistance of the prepared samples was measured during hydrogen molecule adsorption to investigate the hydrogen adsorption mechanism. It was found that the electrical resistance changed as a result of the easy hydrogen molecule approach, as well as of the adsorption process and the catalyst. It was also notable that the catalyst improved not only the hydrogen storage capacity but also the speed of hydrogen storage based on the response time. The hydrogen storage mechanism is suggested based on the effects of expansion, activation, and the catalyst.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.99-102
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• 2006

This paper reviews the relevant literatures and investigates spalling mechanism of high strength concrete, in order to clearly inform spalling problem in fire. Firstly, we studies literatures on spalling occurrence and resistance methods. Secondly chemical change of concrete components in elevated temperature was presented. Finally, mechanism of the spalling occurrence and spalling resistance were carried out with fiber content. In addition, our research team introduced spalling mechanism, being different from other points of view, which has been generally accepted. To secure this mechanism theory, we investigate spalling properties of certain specimens fabricated by roller spindle and made with mortar or concrete condition.

• Geotechnical Engineering
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• v.12 no.6
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• pp.21-36
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• 1996

The stress transfer mechanism between soil and grid reinforcements involves two basic mechanism : frictional soil resistance and passive soil resistance. However the mechanism of the passive soil resistance is very complex to understand. To study the failure mechanism of ribbed reinforcement, the direct shear tests which are dominated by passive soil resistance are analyzed by using the finite element method. The finite element method is used to examine the effects of ribs on this passive soil resistance development and the met hanism of failure. The calculated behavior of the ribbed reinforcement is compared with the measured behavi or. Comparisons between the measured and the simulated strain pat terns, failure modes and load displacement relationship are presented. The behavior of the ribbed reinforcements in a cohesive soil is predicted on the basis of a good agreement between the measured and the Predicted behavior of the Ottawa sand.

• YAKHAK HOEJI
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• v.42 no.2
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• pp.175-180
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• 1998

Bifidobacterium bifidum OFR9 that exhibits acquired resistance to rifampicin and fluoroquinolones was selected by MNNG and multi-step mutation method. To investigate the resistance mechanism to rifampicin in the strain, RNA polymerase from B. bifidum parent strain and rifampicin-resistance OFR9 was partially purified and its sensitivity to rifampicin was assayed. The profile of RNA polymerase preparation of B. bifidum parent and B. bifidum OFR9 is similar to that of E. coli RNA polymerase that includes the basic subunits of ${\beta}$`, ${\beta},\;{\sigma},\;{\alpha}$ but which are a little different in size when they are compared with E. coli RNA polymerase subunits. RNA polymerase isolated from the parent strain was inhibited by 1${\mu}$g/ml rifampicin but that from B. bifidum OFR9 was not affected by 100${\mu}$g/ml concentration of rifampicin. RNA polymerase activity of B. bifidum OFR9 was maintained over 90% through that rifampicin concentration. This result is consistent with MIC values of in vitro test. It can be concluded that the mechanism of rifampicin resistance in B. bifidum OFR9 is due to an alteration of RNA polymerase.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.43-51
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• 2003

The resistance mechanism of anchor changes according to the types of anchor. Friction anchors are classified into tension and compression types. In this study, the characteristics and mechanism of pullout are analysed, and the design method of anchor and computer program for design are developed through compression test results of anchor body grout. The characteristics of compression anchor, compared with tension anchor, are summarized mainly as follows: (1) The effect of progressive failure of compression anchor body are much smaller than those of tension anchor during pullout of anchor: (2) The skin friction resistance is increased by Possion effect of grout (anchor body) during pullout of compression anchor.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.447-454
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• 1994

Wear resistance and wear mechanism of hypereutectic Al-($15{\sim}40$)wt%Si alloys were investigated. Primary Si particles under $20{\mu}m$ size were formed in hypereutectic Al-Si alloy powders due to rapid solidification. But the Si particles of extruded bars were finely distributed in smaller size than that of atomized powders. The wear mechanism of hypereutectic Al-Si alloys was divided into three types of wear phenomena, which were abrasive wear, delamination wear and severe adhesive wear according to sliding speed and load. At low sliding speed and load, wear mechanism was abrasive wear, so Al-15wt%Si alloy showed the best wear resistance. At high sliding speed and load, wear mechanism was adhesive wear, and Al-40wt%Si alloy showed the best wear resistance.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1995.06b
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• pp.97-117
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• 1995

Copper resistance in Pseudomonas syringae pv. tomato is determined by copper-resistance operon (cop) on a highly conserved 35 kilobase plasmid. Copper-resistant strains of Pseudomonas syringae containing the cop operon accumulate copper and develop blue clonies on copper-containing media. The protein products of the copper-resistance operon were characterized to provide an understanding of the copper-resistance mechanism and its relationship to copper accumulation. The Cop proteins CopA (72 kDa), CopB (39 kDa), and CopC (12 kDa) were produced only under copper induction. CopA and CopC were periplasmic proteins and CopB was an outer membrane protein. Leader peptide sequences of CopA, CopB, and CopC were confirmed by amino-terminal peptide sequencing. CopA, CopB, and CopC were purified from strain PT23.2, and their copper contents were determined. One molecule of CopA bound 10.9${\pm}$1.2 atoms of copper and one molecule of CopC bound 0.6${\pm}$0.1 atom of copper. P. syringae cells containing copCD or copBCD cloned behind the lac promoter were hypersensitive to copper. The CopD (32 kDa), a probable inner membrane protein, function in copper uptake with CopC. The Cop proteins apparently mediate sequestration of copper outside of the cytoplasm as a copper-resistance mechanism.