• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.1-11
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• 2000

Relining and rebasing are essential for long-term success and oral health in removable prosthodontics. Major features of failures between metal base and relining resins are adhesive failure due to lack of chemical bonding. The purpose of this study was to find a better metal primer and metal surface treatment method that enhance the bonding strength with relining resin materials. The surfaces of ticonium alloys were treated with $25{\mu}m$ sandblasting (Group A), stone wheel(Group B), stone wheel and EZ oxisor(Group C), $75{\mu}m$ sandblasting(Group D) and EZ oxisor application after $75{\mu}m$ sandblasting(Group E). They were subdivided into no primer application (Group I), MR bond application(Group II) and Metafast bonding liner (Group III). Then specimens were completed though being bonded with relining resins. The specimens were stored in $38^{\circ}C$ water for 48 hours and tensile strength was measured using the universal testing machine. The results were as follows, 1. Primer application groups showed higher bond strength than no primer application group(p<0.05). 2. In comparison with primer application groups, MR bond group showed higher bond strength than Meta fast bonding liner application group(p<0.05). 3. In comparison with surface treatment methods, Bond strengths of group A and B were significantly different with group C, D, and E, and group C were significantly different with group D, and E in no primer application group()(0.05). In primer application groups, group A, B, C were significantly different with group D and E(p<0.05). According to results of this study, Metal primer application and metal surface roughening were considered to be advantageous for relining of metal base dentures.

• Transactions on Electrical and Electronic Materials
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• v.7 no.3
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• pp.149-153
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• 2006

An attempting to produce a p-type diluted magnetic semiconductor (DMS) using $Ti_{1-x}Co_xO_{2-\delta}-based$ thin films was made by suitable control of the deposition parameters including deposition temperature, deposition pressure, and doping level using a pulsed laser deposition method. T$Ti_{0.97}Co_{0.03}O_{2-\delta}-based$ (TCO) films deposited at $500^{\circ}C$ at a pressure of $5\times10^{-6}$ Torr showed an anomalous Hall effect with p-type characteristics. On the other hand, films deposited at $700^{\circ}C$ at $5\times10^{-6}$ Torr showed n-type behaviors by a decreased solubility of cobalt. The charge carrier concentration in the p-type TCO films was approximately $7.9\times10^{22}/cm^3$ at 300 K and the anomalous Hall effect in the p-type TCO films was controlled by a side-jump scattering mechanism. The magnetoresistance (MR), measured at 5 K in p-type TCO films showed a positive behavior in an applied magnetic field and the MR ratio was approximately 3.5 %. The successful preparation of p-type DMS using the TCO films has the potential for use in magnetic tunneling junction devices.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.283-294
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• 1987

One hundred and fifty-seven strains of staphylococci isolated from various clinical specimens and 80 of Gram-negative bacilli from urine of patients with urological diseases were tested for resistance to antimicrobial drugs by microdilution broth method. Among staphylococci, 50 to 89% of the strains were resistant to gentamicin(Gm), kanamycin(Km), erythromycin(Em), nalidixic acid(Na), and tetracycline. Ninety per cent MIC was lowest in ciprofloxacin(Cp), followed by vancomycin(Vc), trimethoprim(Tp), enoxacin(Ex), and norfloxacin(Nf) with the values of two ${\mu}g/ml$ or lower. Twenty-seven strains were resistant to methicillin(MR), with 24 strains of Staphylococcus aureus and 3 of S. epidermidis. All strains of MR S. aureus were resistant to oxacillin, rifampin(Rf), Gm, Km, Em, Na, and Tc, and no strain was resistant to Vc and Tp. Almost all staphylococci isolated from urine were S. epidermidis and sensitive to most drugs tested without MR strain. Among Gram-negative bacilli from urine, Escherichia coli(43 strains) was most frequently isolated, and followed by Klebsiella spp.(11), Proteus spp.(10), Serratia spp.(10), and Pseudomonas aeruginosa(6) in the decreasing order. The majority of E. coli and Serratia spp. were resistant to chloramphenicol(Cm), Tc, streptomycin, sulfisomidine(Su), ampicillin(Ap), Km, and carbenicillin(Cb), and 50 and 90% MICs of these drugs were also high. In Klebsiella spp., 54% or more were resistant to Cm, Su, Ap, cephalothin, and Cb. Proteus spp. were susceptible to most drugs tested, but Pseudomonas were resistant to nearly all drugs tested except Rf, amikacin, and moxalactam(Mx). All Gram-negative bacilli tested were found to be susceptible to Mx. New quinolone carboxylic acid compounds, such as Nf, Ex, and Cp showed very high antimicrobial activities against the majority of organisms tested except Pseudomonas, and 50 and 90% MICs of Nf and Ex were always equal or 2 to 4 times higher than Cp. Organisms multiply resistant to drugs were noted in almost all isolates tested. Twenty-seven strains of staphylococci were multiply resistant to 11 or more drugs, and 6 of Klebsiella spp. to 8 to 11 drugs. The most frequent multiplicity of durg resistance were 7 and 8, 12, and 13 in E. coli, Serratia spp., and Pseudomonas, respectively. No strain was resistant to more than 5 drugs in Proteus spp..

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.513-519
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• 2021

Metallic suture anchors are very useful and common fixation devices that are inserted into the target bone to sustain the tendon of a patient with musculus supraspinatus tendon ruptures. On the other hand, the presence of a metallic material prosthesis, such as a metal suture anchor, causes severe MR imaging artifacts, including field distortion, signal loss, and failure of fat suppression. The difference in magnetic susceptibility between metal and other organic materials causes magnetic field distortion surrounding the prosthesis. The resulting magnetic field inhomogeneity makes the images with a lower signal-to-noise ratio and distortion. For a patient with a suture anchor implanted, MR imaging is the golden standard for determining the postoperative prognosis, and a fat-saturation sequence is one of the imaging methods most affected by metal-induced artifacts. In this study, three fat-saturation sequences were compared. Artifact quantification and contrast comparison between the supraspinatus tendon and the surrounding muscle were presented. The images obtained using the STIR pulse sequence showed fewer susceptibility artifacts and better visibility in the supraspinatus tendon and the tissue area. Therefore, the STIR sequence is the most appropriate fat-saturation imaging method for patients with a metallic prosthesis.

• Korean Journal of Materials Research
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• v.2 no.2
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• pp.126-132
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• 1992

Experiment has been performed to investigate the thermal and magnetic properties of Mn-ferrite by electrolysis. Using the 0.2%C mild steel as soluble anode and SUS 304 stainless steel as cathode, Mn-ferrite could be made from the sulfuric acid leaching of the wasted manganese dry cell and $MnSO_4$reagent by electrolysis. As the result of X-ray diffraction, thermal analysis and magnetic measurement, Mn-ferrite was the spinel type in $Mn_{x}Fe_{3-x}O_4$ (X=1), the weight loss rate of $Mn_{x}Fe_{3-x}O_4$ were linearly increased up to the $200^{\circ}C$. Ms, Mr and Hc values were decreased with increasing Mn content and heating temperature. When Mn-ferrite was formed by $MnCl_2$reagent electrolysis, Ms values were higher than those formed from the sulfuric acid leaching of the wasted manganese dry cell and $MnSO_4$reagent by electrolysis. In Mn-ferrite, which was formed from the sulfuric acid leaching of the wasted manganese dry cell by electrolysis, Ms and Mr values were higher, Hc values were lower than which was formed by $MnSO_4$ reagent electrolysis at $200^{\circ}C\;and\;300^{\circ}C, while the same values at $100^{\circ}C$. The shape of particles was spherical type, the sizes of them were about $0.1{\mu}m$ sub-micron in $MnSO_4$reagent electrolysis, $0.5{\mu}m$ in the sulfuric acid leaching of the wasted manganese dry cell by electrolysis.

• Korean Journal of Materials Research
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• v.10 no.6
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• pp.437-444
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• 2000

We investigated the effect of substrate temperature, chemical composition and post-deposition heat-treatment on the crystal structure and electrical transport of $La_{1-x}Sr_xMnO_{3-{\delta}}$(0.19${\leq}x{\leq}$0.31) thin films. As-prepared $La_{1-x}Sr_xMnO_{3-{\delta}}$ films grown at $500^{\circ}C$ by sputter techniques were found to have the pseudo-tetragonal system(a/c=0.97) and a highly preferential <001> orientation. The films were changed to be of the cubic system by post-deposition annealing at around $900^{\circ}C$. A main target of $La_{0.67}Sr_{0.33}MnO_3$ as well as auxliary targets of $La_{0.3}Sr_{0.7}MnO_3$ ceramics were co-sputtered to control the chemical composition of the film. The Sr content(x) of the film ranged from 0.19 to 0.31, depending on the number of the auxiliary target. When x increased from 0.19 to 0.31, the electrical resistivity of the film decreased and the transition temperature between metal and semiconductor shifted to higher temperature. With a magnetic field of 0.18 T, the magneto-resistance ratio (MR(%) = (${\rho}_o-{\rho}_H/{\rho}_H$) of the $La_{0.69}Sr_{0.31}MnO_3$ thin film was about 390%.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.652-660
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• 1993

It was investigated to obtain the relationship between magnetic properties and conditions of forming $Fe_{3}C$ single phase from acicular goethite by heat treatment under the atmosphere of CO and $N_{2}$ mixed gas. X-ray analyses, TEM and VSM measurements were imployed for the characteristics of the carbide. Acicular goethite was sinthesized under proper process parameters. $Fe_{3}C$ single phase was obtained above $550^{\circ}C$, 60min. and $Fe_{5}C_2$ was formed with $Fe_{3}C$ below that temperature. The soturation magnetization of $Fe_{3}C$ single phase was about 100emu/g regardless of the reaction temperature. The coersive force and the ratio of Mr/Ms decreased respectively from 780 to 400 Oe. and from 0.35 to 0.13 with increasing reaction temperature.

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.737-741
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• 2003

Polycrystalline $Ti_{l-x}$ $Co_{x}$ $O_2$thin films on $SiO_2$ (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed $Ti_{l-x}$ $Co_{x}$ $O_2$thin films with $x\leq$0.05 showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the X$l-x_{l-x}$ $Co_{x}$X$O_2$phases. On the other hand, in case of thin films above x = 0.05, Co-rich clusters formed in a homogeneous $Ti_{l-x}$ $Co_{x}$ $O_2$phase, and the overall ferromagnetic (FM) properties depended on both FMTCO and FMCo. Co-rich clusters with about 10-150 nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.21.2-21.2
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• 2011

$Fe_3O_4$ having half metallic property is one of the efficient spin filtering materials which are widely used in spintronic research field and ZnO is wide band gap semiconductor which can be used by tunnel barrier or semiconductor channel in spin MOSFET. We investigated the magnetic and the electric properties of $Fe_3O_4$/ZnO multilayer fabricated on c-$Al_2O_3$ substrate by pulsed laser deposition (PLD). For multilayer films, PLD was performed at variable temperatures such as $200{\sim}750^{\circ}C$ and at target distance from 40 to 80 mm, KrF eximer laser of 1.5 $J/cm^2$ and a reputation rate of 2Hz. $Fe_3O_4$/ZnO multilayers were deposited at $4{\times}10^{-6}$ Torr. After fabricating $Fe_3O_4$/ZnO multilayers, $Fe_3O_4$/ZnO multilayers were treated by RTA(Rapid Thermal Annealing) at various temperature to change magnetic phase. The magnetism of the multilayer is changed by thickness of the ZnO tunnel barrier. Magnetic phase of FexOy showed a very small magnetism due to $Fe_2O_3$ ${\alpha}$-phase, but large magnetism from $Fe_3O_4$ or $Fe_2O_3$ ${\gamma}$-phase was observed. In the present study, effect of the ZnO thickness on the MR (magnetoresistance) ratio was investigated in detail.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.613-618
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• 2003

The magnetic heating effect of $SiO_2$coated $ \Upsilon-Fe_2$$O_3$nanocomposite particle due to magnetic relaxational loss of superparamagnetic regime was investigated by measuring the generated heat from nanocomposite particles in alternative applied magnetic fields. The commercial $ \Upsilon-Fe_2$$O_3$nanoparticles were coated by SiO$_2$in water solution with TEOS and the synthesized nanocomposite powders and its magnetic properties were characterized and compared with the raw$ \Upsilon-Fe_2$$O_3$nanoparticles. The 10∼30 nm sized $ \Upsilon-Fe_2$$O_3$. nanoparticles were coated by 5 nm thickness of amorphous $SiO_2$film. The nanocomposite particle has very low Mr and Hc value showing superparamagnetic behavior The magnetic heating effect of nanocomposite particle on surface coating phase of $SiO_2$was discussed in terms of superparamagnetic behaviors of each particles, and their potential for hyperthermia application was evaluated.