• Korean Journal of Materials Research
• /
• v.26 no.3
• /
• pp.130-135
• /
• 2016

To alloy high melting point elements such as boron, ruthenium, and iridium with copper, heat treatment was performed using metal oxides of $B_2O_3$, $RuO_2$, and $IrO_2$ at the temperature of $1200^{\circ}C$ in vacuum for 30 minutes. The microstructure analysis of the alloyed sample was confirmed using an optical microscope and FE-SEM. Hardness and trace element analyses were performed using Vickers hardness and WD-XRF, respectively. Diffusion profile analysis was performed using D-SIMS. From the microstructure analysis results, crystal grains were found to have formed with sizes of 2.97 mm. For the copper alloys formed using metal oxides of $B_2O_3$, $RuO_2$, and $IrO_2$ the sizes of the crystal grains were 1.24, 1.77, and 2.23 mm, respectively, while these sizes were smaller than pure copper. From the Vickers hardness results, the hardness of the Ir-copper alloy was found to have increased by a maximum of 2.2 times compared to pure copper. From the trace element analysis, the copper alloy was fabricated with the expected composition. From the diffusion profile analysis results, it can be seen that 0.059 wt%, 0.030 wt%, and 0.114 wt% of B, Ru, and Ir, respectively, were alloyed in the copper, and it led to change the hardness. Therefore, we verified that alloying of high melting point elements is possible at the low temperature of $1200^{\circ}C$.

• Korean Journal of Clinical Laboratory Science
• /
• v.50 no.4
• /
• pp.431-437
• /
• 2018

Acinetobacter baumannii is categorized as a red alert pathogen that is increasingly associated with a high mortality rate in infected patients because of its resistance to extensive antibiotics. This study evaluated the antibacterial activities of some essential oils (tee tree, rosemary, and lavender oils) against 18 clinical isolates of multidrug-resistant A. baumannii (MRAB). The carbapenemase screening Hodge test showed that all 20 strains of A. baumannii were resistant to imipenem. The identification of multidrug-resistant microbes was carried out using the VITEK system. The antimicrobial activity of essential oils was tested by a disk diffusion method against MRAB. In the disk diffusion method, tea tree showed the largest increase in inhibition size compared to lavender oil, and rosemary had no antibacterial effect. These results proved the antimicrobial effect of multidrug resistance A. baumannii. Tee tree oil would be a useful alternative natural product for the treatment and prevention of most common human pathogens and MRAB infections. This is expected to be used as an antimicrobial agent, such as hand disinfectant using natural essential oil in the future.

• Journal of the Korean Society of Radiology
• /
• v.81 no.3
• /
• pp.467-487
• /
• 2020

Anatomical imaging is the basis of the diagnosis and treatment response assessment of brain tumors. Among the existing imaging techniques currently available in clinical practice, diffusion-weighted imaging and perfusion imaging provide additional information. Recently, with the increasing importance of evaluation of the genomic variation and heterogeneity of tumors, clinical application of imaging techniques using radiomics and deep learning is expected. In this review, we will describe recommendations for magnetic resonance imaging protocols focusing on anatomical images that are still important in the clinical application of brain tumor imaging, and the basic principles of diffusion-weighted imaging and perfusion imaging among the advanced imaging techniques, as well as their pathophysiological background and clinical application. Finally, we will review the future perspectives of radiomics and deep learning applications in brain tumor imaging, which have been studied to a great extent due to the development of computer technology.

• Journal of Information Technology Applications and Management
• /
• v.18 no.4
• /
• pp.169-181
• /
• 2011

The study developed the ideas of innovation resistance attitude in view of innovation delay, rejection, and objection. Authors developed the idea of innovation resistance attitudes of customers in view of innovation diffusion process. The study categorized the idea of resistance such as delay, rejection, and objection. The study hired the structural equation modeling to evaluate the relationships among the consumers' subjective variables such as incongruence, uncertainty, perceived performance, peer usage, and tradition orientation those were factored out by the survey test. These measured variables were analyzed into the innovation resistance related latent variables. The study provides the basic treatment to introduce new technologies and products to the superficially resisting customers. Those resisting customers might be future late adopters. The research results provide the basic arguments for prerequisite treatment to introduce smart phone in the global market place.

• Journal of the Korean institute of surface engineering
• /
• v.31 no.6
• /
• pp.325-333
• /
• 1998

A duplex surface treatment process of simultaneous aluminizing-chromizing process followed by plasma nitriding was performed on AISI HI3 steel and STS 403 steel. The properties of these duplex-treated steels were investigated and were compared with those of steels treated by single process of either simultaneous aluminizing-chromizing or plasma nilriding, in terms of microstructure, microhardness and high temperature wear resistance. Sim~dtaneous alumizing-chromizing process was done using a 2-step coating cycle and plasma nitriding process was done at $530^{\circ}C$ for 1.5 hour. AISI HI3 steel and STS 403 steel showed a FeA1 compound layer of approximately 350$\mu\textrm{m}$ thickness on the surface after simultaneous diffusion coating and nitrided layer of approximately 70-80$\mu\textrm{m}$ formed after the subsequent plasma nitriding process. The microhardness was improved much more by the duplex surface heatment than only by plasma nitriding. In addition the duplex treated specimens showed an improved high temperature wear resistance.

• Journal of the Korean institute of surface engineering
• /
• v.34 no.6
• /
• pp.568-574
• /
• 2001

Mixed powders of Fe + 0.7% C, Fe + 0.7% C + 1.6% Cu, and Fe + 0.7% C + 0.3% MnS were pressed in a mold so that the green-compact densities were 6.3, 6.5, 6.7, and 6.9 g/㎤, respectively. Then, the compacts were sintered at $1125^{\circ}C$ for 30 minutes and subsequently steam treated at $600^{\circ}C$ for 60 minutes. From the results, it was found that the overall properties of the steam-treated compacts, such as the weight gain of the sintered compacts, the diffusion of oxides into the sintered compacts, the surface hardness, and the formation of surface oxide layer, were primarily influenced by the density of the compacts and the oxides that were formed on the surface of the compacts by the steam treatment.

• Journal of the Korean Society for Heat Treatment
• /
• v.7 no.4
• /
• pp.318-327
• /
• 1994

According to conventional nitriding of tool steels, it was very difficult to produce a high surface hardness. This study has been conducted to investigate the influence of initial structures on the nitriding characteristics of tool steels in gas-nitrided for the improvement in surface hardness. The specimens (SACM645, STD61 steels) have been quenching and tempering at various temperature and then gas-nitrided for 30, 45 and 60hr at 500, 530 and $550^{\circ}C$ respectively in gasatmosphere of 30%$NH_3-70%N_2$ As hardness of initial structure was higher, the nitriding layer was deeper and hardness of the nitriding layer was higher. Deeper nitriding layers was due to higher diffusion rate by fine initial microstructure. Also the reason of high surface hardness was associated with formation of dispersed fine carbonitrides of nitrides.

• Microbiology and Biotechnology Letters
• /
• v.25 no.2
• /
• pp.183-188
• /
• 1997

Antimicrobial activity of various extracts of Xanthium strumarium L. was tested against 25 strains of bacteria, yeast and fungus. The crude ethylacetate extract exhibited strong growth inhibition to the tested strains with the exception of partial Gram-negative bacteria. The property of antimicrobial compound was very stable under heat treatment at $120^{\circ}C$, but it was unstable in acid (pH 3.0) and alkali (pH 10.0) treatment. The antimicrobial compounds were purified by boiling water extraction, ethylacetate extraction, charcoal column chromatography, silica gel column chro- matography and reverse phase HPLC. The purified compound A and B were detected in a single peak (each above 98% purity) through the HPLC analysis. The compound A and B showed a strong growth inhibition against Gram-negative and positive bacteria in the agar diffusion method. When tested by the FDA method using the esterase, compound A mainly inhibited the growth of bacteria and compound B showed the growth inhibition of both bacteria and yeasts.

• The International Journal of Costume Culture
• /
• v.5 no.2
• /
• pp.53-65
• /
• 2002

Morphology of polyester fiber was physically modified by solvent treatment. PET fiber was treated with N,N-dimethylformamide (DMF) at 100, 120, $140^{circ}C$ for 10 minutes without tension. The structural changes in the morphology of DMF-induced modified PET fiber were FTIR and SEM analysis. Also dyeing behavior of DMF-treated polyester fibers with various disperse dyes was studied to detect changes of amorphous area in fine structure. DMF treatment resulted in increases in total void content, degree of crystallinity, trans isomer content, chain folding, segmental mobility and molecular packing, but it resulted in decreases in amorphous orientation, intermolecular forces and individual void size through longitudinal shrinkage, lateral welling and removal of oligomers. Void-size distribution could be estimated from the dye uptake with various sizes of disperse dyes. In contrast to the large increases in dye uptake with small dye molecules, there is no and little dye uptake with the bulkiest dye, which means that void size is bigger or smaller than the volume of each dye. Diffusion rates of dye molecules showed increases. This dyeing study revealed that the disperse dyeing is very effective method for characterizing the internal morphology of polyester fiber.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.352.2-352.2
• /
• 2014

In this present work, we report a Cu-Mn alloy as a materials for the self-forming barrier process. And we investigated diffusion barrier properties of self-formed layer on low-k dielectrics with or without UV curing treatment. Cu alloy films were directly deposited onto low-k dielectrics by co-sputtering, followed by annealing at various temperatures. X-ray diffraction revealed Cu (111), Cu (200) and Cu (220) peaks for both of Cu alloys. The self-formed layers were investigated by transmission electron microscopy. In order to compare barrier properties between Mn-based interlayer interlayer, thermal stability was measured with various low-k dielectrics. X-ray photoelectron spectroscopy analysis showed that chemical compositions of self-formed layer. The compositions of the Mn based self-formed barriers after annealing were determined by the C concentration in the dielectric layers.