• International Journal of High-Rise Buildings
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• v.13 no.1
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• pp.85-95
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• 2024

A composite member made of concrete-filled steel tubes (CFT columns) has been recognized for its fire resistance due to the thermal mass effect of concrete inside the steel tube, as shown in various studies. In this study, the fire resistance performance of reinforced CFT columns under constant axial load was evaluated using finite element analysis with ABAQUS. For this purpose, the variables including cross-section size, steel tube thickness, and concrete cover thickness were set, and the temperature distribution in the column cross-section exposed to a standard fire was investigated using heat transfer analysis. Ultimately, a P-M interaction curve was obtained by evaluating the overall residual strength of columns, and the fire resistance time was determined by evaluating axial displacement-time responses due to the reduction in load capacity during fire through stress analysis.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.655-663
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• 2008

In this research, the fire resistance of Concrete-Filled Circular Steel Tube Columns (CFT) was evaluated by numerical analysis. As the materials of CFT columns, the steel of SPSR 400 grade and the concrete of 27.5MPa, 37.8MPa strengths were used. Significant parameters,such as concrete strength, axial load, and cross-sectional dimensions were determined. To verify the accuracy of the numerical analysis,the analysis results were compared with the former experiment results. The effect of the fire resistance time, axial load ratio, cross-sectional dimensions and concrete strength was evaluated by comparison with the fire resistance of the square CFT columns. This research showed that the structural behavior and fire resistance from the findings of numerical parametric studies showed a similarity to that of the experimental results. Therefore, this numerical analysis is reasonable in estimating the fire resistance of the circular CFT column.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.703-714
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• 2007

The aim of this research is to evaluate the fire resistance of concrete-filled steel square tube columns (square CFT columns) under constant axial loads by numerical analysis. The authors examined the experimental results on the fire resistance of concrete-filled steel square tube columns without fire protection. As the materials of CFT columns, steel of SPSR 400 grade and concrete of 27.5MPa and 37.8MPa strengths were used. The significant parameters were determined, such as load ratio, cross-sectional dimensions, and concrete strength. Detailed analytical simulations of fire resistance and axial deformation showed good agreement with the experimental observations. Therefore, this numerical analysis exhibited a reasonable estimation of fire resistance of the square CFT column. Results of the numerical parametric studies showed that the fire resistance of the CFT columns increased with the decrease of the concrete strength and the increase of the cross-sectional dimensions about the constant axial load ratio ($N/N_c$).

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1106-1111
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• 2014

This paper has a purpose to find out the characteristics of pressure distribution according to the POD shape installed in the Hydrofoil vessel, using the CFD. The results showed that as we cut the POD cross-section's basic shape along the x-axis from 0 to 8cm, the viscous resistance had decreased, but then the pressure resistance had increased modestly. However, the cutoff length of POD cross-section shape has close to 9cm, the viscous drag had increased and the pressure drag had decreased. As a result, we found out that the pressure resistance made more effects in POD shape than the viscous resistance, and the total resistance decreased near the 9cm of cutoff length.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.74-80
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• 1994

The german cockroach, Blattello germanica L, populations were successively selected with dlchlowos for 11 generations. The resulting selected shin was investigated the resistance development. the cross resistance and the esterase actim@. In the dichlowos-selected(Rd) strain, the values of LCs increased 858 times more compared to the susceptible (S) strain. In the dich!o~vos-selected (Rd) strains, the cross-res~stance to chlorpyrifos, propoxur, fenvalerate and pemethnn showed 3.35. 4.09. 283 and 2.00 times. Esterase.activity of the Rd strain showed 1.33 times higher than that of the S strain in the filter paper test. In comparison of zymogram paitems of the estemse isoryme by thin agarose gel electrophoresis against the german cockroach, the S strain was separated by 4 bands uf esterase 3, 5, 6 and 8 bands and the Rd strain was separated by 6 bands of esterase 1, 2, 4, 5, 7 and 8 bands, and the resistant mechanisms of the Rd strain were considered as the 4 bands of esterase-1.2.4 and 7 bands except the common 2 bands of esterase.6 and 8 bands.

• Korean journal of applied entomology
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• v.10 no.2
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• pp.121-125
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• 1971

• Journal of Microbiology
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• v.45 no.1
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• pp.64-68
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• 2007

In this study we examined the multi-drug resistance profiles of the tetracycline (TC) resistant genus Vibrio to determine its susceptibility to two ${\beta}-lactams$, ampicillin (ABPC), and mecillinam (MPC), as well as to macrolide, erythromycin (EM). The results showed various patterns of resistance among strains that were isolated from very close geographical areas during the same year, suggesting diverse patterns of drug resistance in environmental bacteria from this area. In addition, the cross-resistance patterns suggested that the resistance determinants among Vibrio spp. are acquired differently within the sediment and seawater environments.

• BMB Reports
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• v.42 no.8
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• pp.475-481
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• 2009

Emerging data demonstrate pivotal roles for brain insulin resistance and insulin deficiency as mediators of cognitive impairment and neurodegeneration, particularly Alzheimer's disease (AD). Insulin and insulin-like growth factors (IGFs) regulate neuronal survival, energy metabolism, and plasticity, which are required for learning and memory. Hence, endogenous brain-specific impairments in insulin and IGF signaling account for the majority of AD-associated abnormalities. However, a second major mechanism of cognitive impairment has been linked to obesity and Type 2 diabetes (T2DM). Human and experimental animal studies revealed that neurodegeneration associated with peripheral insulin resistance is likely effectuated via a liver-brain axis whereby toxic lipids, including ceramides, cross the blood brain barrier and cause brain insulin resistance, oxidative stress, neuro-inflammation, and cell death. In essence, there are dual mechanisms of brain insulin resistance leading to AD-type neurodegeneration: one mediated by endogenous, CNS factors; and the other, peripheral insulin resistance with excess cytotoxic ceramide production.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.195-205
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• 1989

Development of drug resistance in tumors during treatment is a major factor limiting the clinical use of anticancer agents. When tumor cells acquire resistance to anticancer drug, they show cross-resistance to other antitumor agents. In the present study, SNU-1 cell was induced adriamycin $10^{-7}M$ drug resistance, SNU-1/ADR, in vitro culture system. We got the doubling time and number for viability test during 96 hours by MTT assay. To investigate the cross resistance of various anticancer drugs in human stomach cancer cell SNU-1 and SNU-1/ADR. We compared $IC_{50}$ (drug concentration of 50% reduction) and the relative resistance(RR). SNU-1/ADR was expressed multidrug resistant with vinblastine(RR ; 31.62), vincristine(RR ; 29.50), dactinomycin(RR ; 21.37), epirubicin(RR ; 17.78), daunorubicin(RR ; 14.12), adriamycin(RR ; 7.76), and etoposide(RR ; 4.46), and other drugs, 5-fluorouracil, cisplatin, cyclophosphamide, methotrexate, and aclarubicin, have not cross resistant with adriamycin. There was double minute chromosome in SNU-1/ADR by karyotyping although this change was not seen in SNU-1.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.1-15
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• 2017

In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, herbicide resistance in weeds should be minimized because it is a major limiting factor for food security. Cross resistance can occur with herbicides within the same or in different herbicide families and with the same or different sites of action. Multiple resistance refers to evolved mechanisms of resistance to more than one herbicide (e.g., resistance to both ALS-inhibitors and ACCase-inhibitors) and this resistance was brought about by separate selection processes. Target site resistance could occur from changes at the biochemical site of action of one herbicide. Non target site resistance occurs through mechanisms which reduce the number of herbicide molecules that reach the herbicide target site. There are currently 480 unique cases (species ${\times}$ site of action) of herbicide resistance globally in 252 plant species (145 dicots and 105 monocots). To date, resistance in weeds has been reported to 161 different herbicides, involving 23 of the 26 known herbicide sites of action. Finally, it can be concluded that we can protect crops associated to herbicide resistant weeds by applications of biochemical, genetic and crop control strategies.