• Journal of Conservation Science
• /
• v.33 no.5
• /
• pp.381-390
• /
• 2017

Desalination is the main focus of the stabilization of iron artifacts. However, drawbacks such as re-corrosion are noted due to the uncertainty in the elimination of the corrosive factors and artifacts. Several studies have been carried out on the effects of corrosion inhibitors to overcome these shortcomings. In this study, the effects of type 3 water treatment on corrosion inhibitors were investigated. Surfaces of samples that contained film corrosion inhibitors on their surfaces were analyzed. The results revealed that the surface rust was removed from the sample of type 1 No. 2 that was mainly composed of phosphate. The average weight reduction rates of re-corrosion samples were 0.58, 0.03, and 0.07% for type 1 No. 2, type 2 No. 2, and type 3 No. 2 respectively. The changes in the $Cl^-$ ion, a corrosive agent were found to be 28.60, -4.08, and -1.94 ppm for type 1 No. 2, type 2 No. 2, and type 3 No. 2 respectively. The water-treated films were analyzed by X-ray photoelectron spectroscopy (XPS). It was found that type 2 No. 2 had less Fe the basis metal, than that in type 3 No. 2 indicating much better film. Moreover, Si content was higher in type 2 No. 2, based on the silicate content, than in type 3 No. 2. They are speculated to be the reason or the formation of a better film. Type 1 No. 2, which is mainly composed of phosphate, would be inappropriate as a metal artifact conservation treatment. It was determined that type 2 No. 2 and type 3 No. 2 water treatments, which are mainly composed of silicate, provided excellent corrosion inhibiting effects. Corrosion inhibitors could be used as emergency treatment agents during the excavation of iron artifacts.

• Journal of Sensor Science and Technology
• /
• v.8 no.5
• /
• pp.414-420
• /
• 1999

The oxide sacrificial layer technology is one of the key technologies in surface micromachining. However, the commonly used aqueous HF solutions, including the $NH_4F$ buffered HF solutions (BHF), are known to attack the Al metal layers during the oxide sacrificial etch. A mixed $NH_4F$/HF/glycerine aqueous solution of 4:1:2 ratio is known to have the best etch selectivity between oxide and AI, but even this sacrificial etchant has a significant etch rate for AI. This paper reports an extensive experimental study on various concentration ratios for HF, $NH_4F$ and glycerine, and develops the optimal mixture ratio for sacrificial etching. At the $NH_4F$/HF/glycerine ratio of 2:1:4, the etch selectivity between PSG and Al improves by approximately 6 times over the previously known best selectivity, to a value of 7,700. At this condition, the measured etch rate of PSG film is approximately $2.1\;{\mu}m/min$, which is sufficiently fast. The developed sacrificial etchant allows the addition of a Al metal layer in surface micromachining, without the worry of Al layer erosion during sacrificial etch.

• Korean Journal of Materials Research
• /
• v.8 no.4
• /
• pp.345-353
• /
• 1998

Metal organic chemical vapor deposition (MOCVD) of copper using three Cu( I ) precursors. (hfac)Cu (VTMS) (hfac= hexafluoroacetylacetonate, VTMS= vinyltrimethylsilane), (hfac)Cu(VTMOS) (VTMOS= vinyltri¬methoxysilane) and (hfac)Cu(A TMS) (A TMS= allyltrimethylsilane) was studied. The thermal stability and the gase¬ous phase reaction mechanism of Cu( I ) precursors were identified using $^1H$-, $^I3C$-NMR and Fourier transform infra¬red spectroscopy. It was found out that thermal stability of liquid phase (hfac)Cu(VTMS) and (hfac)Cu(VTMOS) were better than that of (hfac)Cu(A TMS) using FT - NMR. From in-situ FT - IR experiments, the disproportion reaction of Cu(hfac). the decomposition reaction of Cu(hfac), and cracking of free hfac ligand were observed. Also the effect of gaseous phase reaction on the deposition rates and film properties was investigated. The minimum temperature that deposition of copper films from (hfac)Cu(A TMS) was as low as 60$^{\circ}$C and such a low deposition temperature compared with those of other Cu( I ) precursors is believed to be related with weaken Cu- A TMS bond.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.9 no.6
• /
• pp.711-718
• /
• 2019

Spectrum analyzer and electromagnetic field meter were used to investigate the EM generation behaviour in different types of home electrical appliances. During microwave oven operation, the EM power measured at a point 30cm apart was measured in the range of 8~11mW/㎡, the strength of the low frequency magnetic field was 60~80mG and the electric field strength was measured at 150~160V/m. For smart phone wireless charging pad, it was measured at an electromagnetic power of 0.4mW/㎡, an electric field of 160 V/m and a magnetic field of 1mG at a point 10cm away. For microwave oven and wireless charging pad, if used within 10cm, the size of the electric field has been measured at a large value that exceeds the human body protection standard and may be hazardous to humans. On the other hand, home appliances such as TVs, hairdryers and refrigerators all showed very low levels of electromagnetic waves, electric fields and magnetic fields, with no harmful effects seen. For electromagnetic shielding, the metal Cu fabric and metal foil had a high level of EM shielding, while polymer films had a low EM shielding characteristic.

• Journal of the Microelectronics and Packaging Society
• /
• v.30 no.2
• /
• pp.71-75
• /
• 2023

In this study, inorganic perovskite films with different compositions were grown by thermal chemical vapor deposition depending on the substrate and their optical properties were compared. Inorganic perovskite crystals were grown on SiO₂/Si and c-Al₂O₃ substrates using CsBr and PbBr₂, respectively, under the same growth conditions. Cs₄PbBr₆-CsPbBr₃ crystallites were grown on the SiO₂ with polycrystalline structure, while a CsPbBr₃ (100) dominant thin film was formed on the c-Al₂O₃ substrate with single crystal structure. From the photoluminescence measurement, CsPbBr₃ showed typical green emission centered at 534 nm with a full width at half maximum (FWHM) of about 91 meV. The Cs₄PbBr₆-CsPbBr₃ mixed structure exhibits blue-shifted emission at 523 nm with a narrow FWHM of 63 meV and a fast decay time of 6.88 ns. These results are expected to be useful for application in photoelectric devices such as displays, solar cells, and light sensors based on inorganic metal perovskites.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.1
• /
• pp.88-93
• /
• 2024

To evaluate the possibility as a multi-level memory medium for the Ge₂Sb₂Te₅/TiN/W-doped Ge₂Sb₂Te₅ cell structure, the crystallization rate and stabilization characteristics according to voltage (V)- and current (I)- pulse sweeping were investigated. In the cell structures prepared by a magnetron sputtering system on a p-type Si (100) substrate, the Ge₂Sb₂Te₅ and W-doped Ge₂Sb₂Te₅ thin films were separated by a barrier metal, TiN, and the individual thicknesses were varied, but the total thickness was fixed at 200 nm. All cell structures exhibited relatively stable multi-level states of high-middle-low resistance (HR-MR-LR), which guarantee the reliability of the multilevel phase-change random access memory (PRAM). The amorphousto-multilevel crystallization rate was evaluated from a graph of resistance (R) vs. pulse duration (T) obtained by the nanoscaled pulse sweeping at a fixed applied voltage (12 V). For all structures, the phase-change rates of HR→MR and MR→LR were estimated to be approximately t<20 ns and t<40 ns, respectively, and the states were relatively stable. We believe that the doublestack structure of an appropriate Ge-Sb-Te film separated by barrier metal (TiN) can be optimized for high-speed and stable multilevel PRAM.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.24 no.2
• /
• pp.65-71
• /
• 2018

Paper packs, glass bottles, metal cans, and plastic materials are classified according to packaging material recycling groups that are Extended Producer Responsibility (EPR). In the case of waste paper pack, the compressed cartons are dissociated to separate polyethylene films and other foreign substance, and then these are washed, pulverized and dried to produce toilet paper. Glass bottle for recycling is provided to the bottle manufacturers after the process of collecting the waste glass bottle, removing the foreign substance, sorting by color, crushing, raw materializing process. Waste glass recycling technology of Korea is largely manual, except for removal of metal components and low specific gravity materials. Metal can is classified into iron and aluminum cans through an automatic sorting machine, compressed, and reproduced as iron and aluminum through a blast furnace. In the case of composite plastic material, the selected compressed product is crushed and then recycled through melt molding and refined products are produced through solid fuel manufacturing steps through emulsification and compression molding through pyrolysis. In the recycling process of paper packs, glass bottles, metal cans, and plastic materials, the influx of recycled materials and other substances interferes with the recycling process and increases the recycling cost and time. Therefore, the government needs to improve the legal system which is necessary to use materials and structure that are easy to recycle from the design stage of products or packaging materials.

• Journal of Korea Foundry Society
• /
• v.14 no.3
• /
• pp.274-284
• /
• 1994

SiC fibers were coated with Cu, Ag and Ni metallic thin films by magnetron sputtering in order to improve wetting properties between Al matrix and SiC fiber. The wetting behavior of metal coated SiC fiber by pure Al has been studied at $670^{\circ}C{\sim}900^{\circ}C$ range for $10{\sim}90min$. under vacuum atmosphere. Besides, the effect of coated film thickness on the wettability has been investigated. The wetting behavior and interfacial reaction between Al and SiC fibers were analysed with optical microscope and SEM (scanning electron microscope). The wetting behavior of the as-received SiC fiber with Al melt was not uniform, indicated by the contact angles from less than $90^{\circ} to more Al melt was appeared in the initial stage of reation. It was considered that the metallic thin film played an important role in reducing the interfacial free energy and breaking down the aluminum oxide film by eutectic reaction with Al melt. However the wettability of Ni coated SiC fiber was not improved as much as that of Cu or Ag coated SiC fiber. The improvement of wettability by coating thickness is clearly showed in $1{\mu}m$ coated SiC fiber compared with $0.25{\mu}m$ coated SiC.

• Journal of the Korean Electrochemical Society
• /
• v.11 no.3
• /
• pp.176-183
• /
• 2008

Redox complexes to transport electrodes from bioreactors to electrodes are very important part in electrochemical biosensor industry. A novel osmium redox complexes were synthesized by the coordinating pyridine group having different functional group at 4-position with osmium metal. Newly synthesized osmium complexes are described as ${[Os(dme-bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dme-bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dmo-bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dcl-bpy)}_2{(ap-im)Cl]}^{+/2+}$. We have been studied the electrochemical characteristics of these osmium complex with electrochemical techniques such as cyclic voltammetry and chronoamperommetry. Osmium redox complexes were immobilized on the screen printed carbon electrode(SPE) with deposited gold nanoparticles. The electrical signal converts the osmium redox films into an electrocatalyst for glucose oxidation. Each catalytic currents were related with the potentials of osmium complexes.

• Journal of the Korean Magnetics Society
• /
• v.12 no.6
• /
• pp.231-234
• /
• 2002

Magnetic properties are investigated for top- and bottom-type spin valves of Si/SiO$_2$/NiO(60nm)/Co(2.5nm)/Cu(1.95nm)/Co(4.5nm)/NOL(t nm; Nano Oxide layer). The MR ratios of the bottom-type spin valves with NOL are larger than those of the top-type spin valves. However, the enhancement of the former is lower than the latter. Both of spin-valves also showed almost constant Ap and smaller p. Enhanced MR ratios of spin valves with NOL result mainly from small values of with constant Ap which due to specular diffusive electron scattering at NOL(NiO)/metal interfaces.