• Journal of Environmental Science International
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• v.5 no.5
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• pp.579-583
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• 1996

This study is involved to develop new catalysts to decompose plastics, detergents and surfactants containing synthetic peptide bonds. As the first year research, the catalytic-hydrolysis of amide bond in copper complex was accomplished. The hydrolysis reaction in aqueous solution was monitored by UV/VIS spectroscopy. As the pH of the solution Is increased and the temperature is raised, the reaction rate increases. The reaction rate is observed as the first order kinetic behavior for the copper complex. The metal catalyzed hydrolysis mechanism is proposed cia metal-hydroxide in the pH region of 5.5 to 6.3. The results of characterization of the catalytic reaction mechanism can be applied to develop new catalysts for peptide bond degradation in further research.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.35-40
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• 2004

In order to understand alloying effects on the corrosion resistance of Ti-(10$\sim$20)%Zr-(2$\sim$8%)Nb-0.2%Pd alloys, Polarization curves were measured at 5%HCI solution. The results were interpreted in terms of two parameters obtained by the molecular orbital calculation ; one is the bond order($B_{\circ}$) and the other is the metal d-orbital level($M_{d}$). $B_{\circ}$ is a measure of the strength of covalent bonds between titanium and alloying elements. $M_{d}$ is correlative with the electronegativity of elements. It was found that increasing of Zr and Nb with higher $B_{\circ}$ values showed a lower critical anodic current density in the polarization curve and hence higher corrosion resistance. On the other hand, increasing of Zr and Nb with higher $M_{d}$ values showed a higher corrosion resistance.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.191-205
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• 1993

In order to compare the strength of soldered joints relative to the various sol dering method, soldering processes were performed using Palladium based ceramo-metal alloy(Bond-on 4)and Nickel-cromium alloy(Vera Bond). The obtained data include difference in strength between presoldering and postsoldering The data also contain difference among postsoldered groups for 3 difference soldering methods(torch, infrared. Oven) The following results were obtained : 1. For postsoldering with Pd alloy, the oven-using group showed the highest strength while the difference in strength between the torch-using group and the infrared machine group was negligible. 2. For Pd alloy with the torch method, postsoldering resulted in the higher strength than presoldering. 3. There was a negligible difference in strength between presoldering and postsoldering when Ni-Cr alloy with torch method is used. 4. Through microscopic study of the fractured surfaces, the torch-using group showed more porosity than both the oven-using and the infrared machine groups. 5. In terms of fracturing patterns, the oven-using group showed adhesive failure while both the torch and the infrared machine groups showed cohesive failure and cohesive-adhesive failure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1016-1022
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• 2001

This study presents the microstructure-electrical property relationship of reactive-sputtered Ta$_2$O$_{5}$ MIM capacitor structure processed by annealing in a vacuum and $O_2$ ambience. A microstructural investigation showed the existence of amorphous phase in as-deposited condition and the formation of preferentially oriented-Ta$_2$O$_{5}$ in $700^{\circ}C$ annealing. On annealing under the $O_2$ atmosphere, the Ta$_2$O$_{5}$ film exhibited the trend of its composition\`s approaching to stoichiometry from off-stoichiometry, analyzed by EPMA, the leakage current decrease and the enhanced temperature-capacitance characteristic stability. In the case of low temperature vacuum-annealing treatment, the leakage current behavior was stable irrespective of applied electric field. In the high temperature-annealed film at a vacuum condition, the electrical properties was observed to deteriorate. The results state that in Ta$_2$O$_{5}$ film annealed at $O_2$ atmosphere, gives rise to improvement of electrical characteristics in the capacitor were improved by reducing oxygen-vacancy and dandling Ta-O bond.-O bond.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.93-98
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• 2002

The effect of bonding misfit on single crystallization of transient liquid phase (TLP) bonded joints of single crystal superalloy CMSX-2 was investigated using MBF-80 insert metal. The bonding misfit was defined by (100) twist angle (rotating angle) at bonded interface. TLP bonding of specimens was carried out at 1523K for 1.8ks in vacuum. The post-bond heat treatment consisted of the solution and sequential two step aging treatment was conducted in the Ar atmosphere. The crystallographic orientation analysis across the TLP bonded joints was conducted three dimensionally using the electron back scattering pattern (EBSP) method. EBSP analyses f3r the bonded and post bonded heat treated specimens were conducted. All bonded joints had misorientation centering around the bonded interface for as-bonded and post-bond heat treated specimens with rotating angle. The average misorientation angle between both solid phases in bonded interlayer was almost identical to the rotating angle at bonded interface. HRTEM observation revealed that the atom arrangement of both solid phases in bonded interlayer was quite different across the bonded interface. It followed that grain boundary was formed in bonded interface. It was confirmed that epitaxial growth of the solid phase occurred from the base metal substrates during TLP bonding and single crystallization could not be achieved in joints with rotating angle.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.533-538
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• 1996

A study of shear bond strength between porcelain and alloy pretreated with sandblasting, sputter etching, and sputter etching after sandblasting was established by Instron universal testing machine. 1. Sputter etched group after sandblasted(group IV) and sandblasted group(group II) were stronger than control group(group I) (P<0.05). 2. Sputter etched group(group III) and control group(group I) were not different(P>0.05).

• Steel and Composite Structures
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• v.49 no.1
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• pp.19-30
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• 2023

Steel-concrete composite slabs represent a very efficient floor solution combining the key performance of two different materials: the steel and the concrete. Composite slab response is governed by the degree of the interaction between these two materials, mainly depending by chemical and mechanical bond. The latter is characterized by a limited degree of confinement if compared with the one of the rebars in reinforced concrete members while the former is remarkably influenced by the type of concrete and the roughness of the profiled surface, frequently lubricated during the cold-forming manufacturing processes. Indeed, owing to the impossibility to guarantee a full interaction between the two materials, a key parameter governing slab design is represented by the horizontal shear-bond strength, which should be always experimentally estimated. According to EC4, the design of the slab bending resistance, is based on the simplified assumption that the decking sheet is totally yielded, i.e., always in plastic range, despite experimental and numerical researches demonstrate that a large part of the steel deck resists in elastic range when longitudinal shear collapse is achieved. In the paper, the limit strain for composite slab, which corresponds to the slip, i.e., the debonding between the two materials, has been appraised by means of a refined numerical method used for the simulation of experimental results obtained on 8 different composite slab types. In total, 71 specimens have been considered, differing for the properties of the materials, cross-section of the trapezoidal profiled metal sheets and specimen lengths.

• Journal of Surface Science and Engineering
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• v.30 no.4
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• pp.272-280
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• 1997

The Thermal Barrier Coation(TBC) to improve the that barrier and wear resistant propenrty in high temperature ofthe aircraftength between the accumlation of the aircraft engine and the automobile engine has usually the two layer structure. One is a creamic top layer for heat insulation and the other is a metal bond layer to facilitate the bond strength between the top ceramic layer and the substrate. But, the coated layers should be peeled off because of the accumulation of the thermal stress by the differance of the thermal expantion coefficient between metal and ceramics in a hrat cyclic environment. In this study, the intermediate layer by plasm spray process was introduced to reduce the thermal stress. The powders of plasm spray coating were the Yttria Stabilized Zirconia (YSZ), the Magnesia Stabillized Zirconia(MSZ) and NiCrAlY. the intermediate layer was sprayed with the powders of the bond cast for the purpose of test were executed. The high temperature wear resistance tends to decreasnceee wear and thermal shock test were exeucuted. The high temperature were resistance of the YSZ TBC is better that of the MSZ TBC. The wearrsistance tends to decrease accoring to incresing the temperature between $400^{\circ}C$to $600^{\circ}C$. The thermal shock life of the 3 layer TBC with YSZ top casting was the most outstanding thermal shock rsisstasnce. This means that the intermediate layer should play an importnat roll to alleviate the diffrerence of the thermal expansion coef frcients between metallic layer and cermics layer.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.47-50
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• 2002

This paper presents the results of fire resistance properties of high performance concrete varying with fiber kinds and the size of metal lath in order to verify the validities of fiber on the spatting resistance by fire. Metal lath, glass fiber and carbon fiber are used to confine the concrete. According to test results, plain concrete without lateral confinement and confined concrete with glass fiber and carbon fiber show entire failure after exposed to fire, while confined concrete with metal lath take place in the form of slight surface spatting by fire, which has favorable spatting resistance of concrete. As for the effect of the size of metal lath, when the size of metal lath is more than 1.2mm of thickness, the residual strength of concrete exposed to fire maintains more than 80% of its original strength. However, glass fiber and carbon fiber does not perform desirable spatting resistance by fire due to loss of lateral confinement of fiber exposed to fire caused by melting of fiber and reducing bond strength between concrete and fiber.

• Journal of Pharmaceutical Investigation
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• v.36 no.6
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• pp.371-375
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• 2006

Neomycin coupled to a polymer matrix via a metal linker was prepared and evaluated for prolonging antibacterial activity. Microcrystallized cellulose was chemically modified to cellulose xanthate(MCX) to afford metal binding sites. MCX was treated with Cu(II), Fe(III) or Zn(II) followed by reaction with neomycin (Ne). The release of Ne from MCX-Zn(II)-Ne was investigated and its activity duration was measured by ditch plate method. The amount of metal bound to MCX was 0.36 mmol/g matrix, 0.26 mmol/g matrix and 0.56 mmol/g matrix for Cu(II), Zn(II) and Fe(III), respectively. Ne bound to MCX-metal chelates was 0.006 mmol, 0.07 mmol and 0.01 mmol per g MCX for Cu(II), Zn(II) and Fe(III), respectively. The Ne release from MCX-Zn(II)-Ne was sustained even after seven washes, whereas Ne from MC/Zn(II)/Ne mixture was almost completely released in two washes. Antibacterial activity was prolonged with MCX-Zn(II)-Ne and MCX-Fe(III)-Ne, but not with MCX-Cu(II)-Ne when compared with that of free Ne. Taken together, these results suggest that neomycin coupled to MCX via a proper metal linker has a potential as a polymeric antibacterial agent with sustained activity.