• Elastomers and Composites
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• 제25권2호
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• pp.112-116
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• 1990

In this study, as one way of developing the new cross-linking method that is curable in water, kinetic analysis of solution reaction between CR and silane coupling agents was attemped. First, CR was reacted with silane coupling agents in solution state. According to the time, reaction quantity was pursued by gas chromatography. Also, reaction rate coefficient and activation energy were calculated from the reaction quantity. Silane coupling agents which were used in this study were MPS, CPS and VES.

• 대한화학회지
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• 제15권4호
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• pp.199-203
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• 1971

The adsorption method for the determination of the formation constants of the metal complexes with organic acids was developed by using membrane filters. The adsorption method involved the measurements of radioactivities of the adsorbed metal on membrane filters and the filtrate solution after the radioactive metal ion were filtered through membrane filters in the presence of organic ions of varying concentration. Comparing the adsorption method with the ion exchange method, it was seen that the adsorption method was simpler and faster than the ion exchange method. As an example of the metal complex with organic acid yttrium citrate complex was chosen, and the formation constant of the complex obtained by the adsorption method showed $K_f=2.0{\times}10^{-4}(l. mole^{-1})$ at a pH of 7. Also the present study revealed that the carrierfree state of yttrium in aqueous solution was present in the completely ionized state.

• Korean Chemical Engineering Research
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• 제53권5호
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• pp.632-637
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• 2015

Mesoporous $TiO_2$ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. $TiO_2$ granules obtained showed about 400 nm in size, the specific surface area of $74-77m^2/g$, and average pore size of 13-17 nm. The chemical modification of $TiO_2$ granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (${\eta}=6.72%$) was enhanced about 14% higher than primitive nanoparticles.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.78-84
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• 2012

An in-situ optical monitoring method for real-time process monitoring of electrochemical copper deposition (CED) is presented. Process variables to be controlled in achieving desired process results are numerous in the CED process, and the importance of the chemical bath conditions cannot be overemphasized for a successful process. Conventional monitoring of the chemical solution for CED relies on the pH value of the solution, electrical voltage level for the reduction of metal cations, and gravity measurement by immersing sensors into a plating bath. We propose a nonintrusive optical monitoring technique using three types of optical sensors such as chromatic sensors and UV/VIS spectroscopy sensors as potential candidates as a feasible optical monitoring method. By monitoring the color of the plating solution in the bath, we revealed that optically acquired information is strongly related to the thickness of the deposited copper on the wafers, and that the chromatic information is inversely proportional to the ratio of $Cu$ (111) and {$Cu$ (111)+$Cu$ (200)}, which can used to measure the quality of the chemical solution for electrochemical copper deposition in advanced interconnection technology.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.107-114
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• 2003

This study investigated the effect of 2-methoxy ethanol (2-Me) non-solvent as additive included in casting solution. Macroporous polymer membranes were prepared by using polyethersufone (PES)/N-methyl-2-pyrrolidone (NMP)/2-Me casting solution and water coagulant. The phase separation co-process of the vapor-induced phase separation (VIPS) and liquid-induced phase separation (LIPS) were used by means of membrane preparation method. The pore size and pore size distribution were controlled with additive (non-solvent), and measured with Automated Perm Porometer. By increasing additive (non-solvent) in the casting solution, the membranes produced changed from finger structure to sponge structure. That is due to the different diffusion rates. At slow diffusion process, sponge-like structure was formed and at fast diffusion process, finger-like structure was formed. Also relative humidity, evaporation time, temperature of casting solution and coagulation bath etc. had effects on the pore size distribution and the porosity of the membrane.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3483-3485
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• 2011

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.233-233
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• 2006

[ $Y_{2}O_{2}S:Eu$ ], a red phosphor, coated with silica nanoparticles or nanocomposites composed of silica nanoparticles and polymeric materials such as PMMA and PVP was prepared via sol-gel process. Samples were prepared from four different methods coded P1, P2, P3, and P4. P1 includes a conventional sol-gel process and a dip-coating method while P2 has the same procedure with P1 except that nanocomposites containing both silica nanoparticles and polymer prepared by sol-gel process were used as coating materials. In P3 method, phosphors were dispersed in a solution containing silica precursor, i.e., TEOS and then polymerization was performed to coat onto the phosphors surface while P4 followed the same procedure with P3 except that a solution containing both TEOS and organic monomer were used in preparing coating materials. Among various coating methods examined in this study, uniform coating of phosphor could be achieved by using method P4, i.e., phosphor surface coating in a solution containing hydrophobic monomer and TEOS. Furthermore, $Y_{2}O_{2}S:Eu$ red phosphor coated with nanocomposite composed of PMMA matrix and silica nanoparticles exhibited enhanced PL intensity and long-term stability.

• 분석과학
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• 제15권2호
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• pp.180-183
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• 2002

The new useful method for the direct determination of trace boron in iron matrix was studied by applying the precipitation of $Fe(OH)_3$ and ICP-AES. Optimum pH range was 11 ~ 12.5. Linear concentration range of boron was $0.01{\sim}1.0{\mu}g/m{\ell}$ in $5000 {\mu}g/m{\ell}$ solution as iron.

• 전기화학회지
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• 제15권2호
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• pp.90-94
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• 2012

We report nanostructure electrodes with $TiO_2$ as a core and carbon as a shell ($TiO_2$@C) for oxygen reduction in alkaline solution. The structure of core-shell electrodes is characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction method, and X-ray photoelectron microscopy. The electrochemical properties of the $TiO_2$@C electrodes are characterized using a potentiostat and compared with those of carbon supported Pt catalyst. In particular, the core-shell electrode with dominant pyridinic-N component exhibits an imporved electrocatalytic activity for oxygen reduction reaction in alkaline solution.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.