• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.216-219
• /
• 2005

In precision length measurements using optical interferometry based on homodyne or heterodyne principles, it is crucial to have frequency-stabilized monochromatic light sources. To the end, we investigate the possibility of utilizing the optical comb constituted by ultrashort femtosecond pulse lasers generated from a gain medium of titanium-doped aluminium oxide $(Ti:Al_2O_3)$. The optical comb is stabilized by locking to the caesium atomic clock, which allows all the modes of the comb to maintain an extremely high level of frequency stabilization to precision of one part in $10^{16}$. Then, high precision length measurements are realized by extracting a single or group of particularly wanted optical frequency components or by adopting a third-party light source locked to the comb. Required measurement system setup will be presented in detail along with experimental results.

• Advances in nano research
• /
• v.10 no.1
• /
• pp.91-99
• /
• 2021

Silicene is an emerging two-dimensional (2D) semiconductor material which has been envisaged to be compatible with conventional silicon technology. This paper presents a theoretical study of uniformly doped silicene with aluminium (AlSi3) Field-Effect Transistor (FET) along with the benchmark of device performance metrics with other 2D materials. The simulations are carried out by employing nearest neighbour tight-binding approach and top-of-the-barrier ballistic nanotransistor model. Further investigations on the effects of the operating temperature and oxide thickness to the device performance metrics of AlSi3 FET are also discussed. The simulation results demonstrate that the proposed AlSi3 FET can achieve on-to-off current ratio up to the order of seven and subthreshold swing of 67.6 mV/dec within the ballistic performance limit at room temperature. The simulation results of AlSi3 FET are benchmarked with FETs based on other competitive 2D materials such as silicene, graphene, phosphorene and molybdenum disulphide.

• Journal of Technologic Dentistry
• /
• v.43 no.1
• /
• pp.6-12
• /
• 2021

Purpose: This study aimed to compare the shear bond strength between zirconia cores and veneer ceramics as per the sand blasting and liner treatments. Methods: The following 4 groups of zirconia-veneering ceramic specimens were prepared: (1) Group I, untreated; (2) Group II, with 110 ㎛ aluminium oxide (Al2O3) sandblasting; (3) Group III, with liner (IPS e.max ZirLiner; Ivoclar Vivadent); and (4) Group IV, with 110 ㎛ Al2O3 sand blasting and liner. Surface roughness was measured for all the prepared specimens, and the surface morphology was observed using a scanning electron microscope. All the samples (n=40) were fixed with measuring jigs, and shear bond strengths were obtained using a universal testing machine with a crosshead speed of 0.5 mm/min. The shear bond strength data were analyzed using one-way analysis of variance and t-test. The post hoc comparison was performed using the Tukey's test (α=0.05). Results: A significant difference in the surface roughness was observed between the specimens of groups I and II (p<0.05). Surface treatment with liner and sandblasting showed higher shear bond strength between zirconia core and veneering ceramic (p<0.05). Conclusion: The sand blasting and liner treatment increased the shear bond strength between zirconia core and veneering ceramic.

• Korean Journal of Materials Research
• /
• v.10 no.5
• /
• pp.375-381
• /
• 2000

Aluminium foil for electrolytic capacitors was anodized at the voltage of 100V and 140V for 10 minutes in ammonium adipate solution to form aluminum oxide layer on aluminum substrate as an dielectric film. The thickness, the stoichiometry and the crystal structure of the layer were investigated by using RBS and TEM . In addition EIS technique was employed to study the effects of addition of sulfuric acid on the increment of the foil surface area. It was found that the thickness values of the layers anodized at 100V and 140V were about 130 nm and 190 nm respectively and the stoichiometry of the elements of aluminum and oxygen was 2:3. The anodic oxide layer was shown to be amorphous. but the structure irradiated with electron beam resulted in the transformation into crystalline structure of $${\gamma}$-Al_2$$O_3$ . From a comparison of the impedance results and the capacitance variation to investigate the ef- fects of sulfuric acid addition to the etching bath of hydrochloric acid, the EIS techinque could be useful to analyze the capacitance variation.

• The Journal of Korean Academy of Prosthodontics
• /
• v.28 no.2
• /
• pp.53-76
• /
• 1990

The purpose of this study was to evaluate the tensile bond strength of adhesive resins to successively recast Rexillium III and Degudent-U. Recasting was done 4times successively. Specimen $A_1$, were cast by new metal, and $A_2$ by surpus of $A_1$, $A_3$ by surplus of, $A_2$ $A_4$ by surplus of $A_3$, $A_5$ by surplus of $A_4$ plus 50% new metal. The types of surface treatment for resinbonded restoration in this experiment were electrolytic etching by OXY-ETCH(Oxy dental products, Inc., Hillside, New Jersey, U.S,A.), aluminum oxide blasting, anodic oxidation by EZ-OXISOR( Towagiken Co., Kyoto, Japan), electrotinplating by Kura Ace(Kuralay Co., Kyoto, Japan). Three kinds of cementing resin used in this study were Comspan(K.P. Cauil Co, Milford Delaware, U.S.A.), Super Bond C&B(Sun-Medical Co. Ltd., Kyoto,Japan), Panavia EX(Kuralay Co., Ltd., Osaka, Japan). Tensile bond strength was measured by Instron Universal testing machineModel 1125) and all the specimen were observed with SEM(JEOL, JSM-T2000) and mode of bond failure were recorded. The obtained results were as follows : 1. In electrolytic etched group, tensile bond strength was decreassed when recast alloy was used, and tensile bond strength of Compan and panavia EX were not significantly different(P>0.05). 2. In remaining group treated by aluminum oxide blasting, EZ-OXIOR, Kura Ace, tensile bond strength were not changed when recast alloy were used, and tensile bond strength of SuperBond(C&B and Panavia EX were not significantly different(P>0.05). 3. IN SEM evaluation, electrolytic etched group and electrotinplated group exhibited different image when recast alloy was used, and remaining groups treated by aluminum oxide blasting, EZ-OXISOR exhibited the same. 4. IN observation of bond failure, electrolytic etched group exhibited adhesive failure and remaing groups treated by aluminium oxid blasting, EZ-OXISOR, Kura Ace exhibited adhesive and cohesive failure.

• Journal of the Korean Ceramic Society
• /
• v.33 no.3
• /
• pp.285-292
• /
• 1996

The effect of AlN on the thermal conductivity of aluminum oxide pressurelessly sintered at nitrogen atmos-phere was investigated. Increasing aluminium nitride content up to 1~10 mol% the thermal conductivity of $Al_{2}O_{3}$-AlN system was singnificantly decreased and was constant with adding 20 and 25 mol% aluminium nitride. The thermal conuctivity of $Al_{2}O_{3}$ containing 1~10 mol% the thermal conductivity of $Al_{2}O_{3}$-AlN system was singificantly decreased and was constant with adding 20 and 25mol% aluminum nitride. The thermal conctivity of $Al_{2}O_{3}$ containing 1~10 mol% AlN showed a maximum at $1700^{\circ}C$ and decrea-sed with increasing sintering tempertures. This phenomenon was attributed to $\alpha$-$Al_{2}O_{3}$ and ALON formed by reacting $Al_{2}O_{3}$ with AlN up to $1700^{\circ}C$ and the secondary phases such as ${\gamma}$-ALON ($9Al_{2}O_{3}$.AlN)and $\Phi$($5Al_{2}O_{3}$.AlN) phase above $1750^{\circ}C$ The thermal conductivity of $Al_{2}O_{3}$ containing 20 and 25 mol% AlN showed maximum value at $1800^{\circ}C$ Both $\alpha$-$Al_{2}O_{3}$ and ALON existed up to $1600^{\circ}C$ value at $1800^{\circ}C$ Both $\alpha$-$Al_{2}O_{3}$ and ALON existed up to $1600^{\circ}C$ while only AlON phase existed above $1650^{\circ}C$.

• Journal of the Korean Ceramic Society
• /
• v.16 no.1
• /
• pp.31-37
• /
• 1979

The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.

• Journal of Sasang Constitution and Immune Medicine
• /
• v.22 no.3
• /
• pp.141-151
• /
• 2010

1. Objectives: Three herbal formulas (Yuldahanso-tang, Chungsimyonja-tang, and Taeeumjowi-tang) for Taeeumin were applied to investigate the immunological activities on antigen (Ag)-specific or Ag-non-specific immune responses in murine macrophage cell line (RAW 264.7) and ovalbumin (OVA)-immunized mice. 2. Methods: This study was carried out in nitric oxide (NO) synthesis in RAW 264.7 cells and cellular proliferation in mouse splenocytes according to three herbal formulas. C57BL/6 mice were immunized intraperitonially with OVA/aluminium ($100\;{\mu}g/200\;{\mu}g$/mouse) on day 1, 8, and 15. Three herbal formulas were administrated to mice orally for 3 weeks from day 1. On day 22, OVA-, lipopolysaccharide (LPS)-, and concanavalin A (Con A)-stimulated splenocyte proliferation and antibodies (OVA-specific antibodies of the IgG, IgG1, and total IgM classes) in plasma were measured. 3. Results: Yuldahanso-tang and Chungsimyonja-tang increased NO synthesis in RAW 264.7 cells. Three herbal formulas significantly enhanced cellular proliferation by LPS and Con A in splenocytes from OVA-immunized mice (p<.001). Three herbal formulas for Taeeumin also significantly enhanced plasma OVA-specific IgG, IgG1, and total IgM levels compared with the OVA/Alum group. 4. Conclusion: These results suggested that three herbal formulas for Taeeumin could be used as stimulator of immune response.

• Microbiology and Biotechnology Letters
• /
• v.11 no.1
• /
• pp.39-45
• /
• 1983

One of Streptomyces sp. was screened as an antibiotic producing strain against Gram positive bacteria specifically from about one hundred Actinomycetes collections. The isolated KM-48 strain, indexed in our collection, was secreted an anbitiotic in nutrient broth culture. The active principle was extracted with acetone from the lyophilized solid of cultured filtrate. The nonadsorbed elute in aluminium oxide was isolated as a purified homogeneity which revealed a sing1e spot under ultra-violet beam on avicel thin layer chromatography. The isolated antibiotic was sensitive specifically against the Gram positive bacteria and fungi. About fifty percent inhibition of the control growth on Bacillus amyloliquefaciens was 18$\mu\textrm{g}$/$m\ell$. The antibiotic was lavile against thermotreatment and stabled in acidic condition remarkably. The KM-48 was identified as a similar strain to Streptomyces tsusimaensis on its morphological and cultural characteristics.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.28 no.3
• /
• pp.319-326
• /
• 2012

For many years, ceramics have been used in fixed prosthodontics for achieving optimal esthetics. but, they have another use as well. Many studies today show ceramics can be used for biomaterials. In the beginning researchers made a start in the study of aluminium oxide and sapphire for biomaterial. The appearance of Zirconia began a new phase of research. Zirconia was introduced into implantology as an alternative to titanium, because of its white color, good mechanical properties and superior biocompatibility. But it is not easy to surface treatment in comparison with titanium. To overcome the limitation, interconnected porous bodies of zirconia were fabricated by sintering technique. And the technique of coating was developed. Therefore, some zirconia implants are currently available. It is thought that Research of biomaterials as a variety of puposes for the use of zirconia is looking very promising. The purpose of this paper reviews are to evaluation of zirconia as biomaterials.