• 한국세라믹학회지
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• 제53권1호
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• pp.75-80
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• 2016

Ink-jet printing has become a widespread technology with the society's increase in aesthetic awareness. Especially, ink-jet printing using glazed ceramic ink can offer huge advantages including high quality decoration, continuous processing, glaze patterning, and direct reproduction of high resolution images. Recently, ceramic ink-jet printing has been rapidly introduced to decorate the porcelain product and the ceramic tiles. In this study, we provide an effective method to apply ceramic ink-jet decorations on the glass substrates using a oleophobic coating with perfluorooctyl trichlorosilane. The ink-jet printed patterns were much clearer on the oleophobically coated glass surface than the bare glass surface. The contact angle of the ceramic ink was maximized to the value of $64.0^{\circ}$ on the glass surface, when it was treated with 1 vol% PFTS solution for 1 min. The effects of the printing conditions and firing process on the ink-jet printed patterns on the oleophobically coated glass were also investigated.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1341-1345
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• 2006

An electrostatic interaction is responsible for the attachment of gold seeds of 1-3 nm onto APTMS (3-aminopropyl trimethoxysilane)-coated silica cores in the formation of gold clusters. A surface plasmon resonance and morphology of gold clusters were significantly affected by the pH of gold colloids prepared by THPC reducing agent. Gold colloids of alkaline pH induced the heterogeneous deposition of gold seeds onto the silica nanoparticles, probably due to the continuous reduction of residual gold ions during the attachment process. Gold colloids of acidic pH induced the monodisperse deposition of gold seeds, consequently leading to the formation of smooth gold layer on the silica nanoparticles surface. The gold nanoshells (core radius = 80 nm) prepared by gold colloids of pH 3.1 exhibited the more red-shift and relatively stronger intensity of plasmon absorption bands, compared with gold nanoshells prepared by alkaline gold colloids of pH 9.7.

• Corrosion Science and Technology
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• 제17권2호
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• pp.74-80
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• 2018

The electronic industries require environmentally-friendly and highly functional materials to enhance the quality of human life. Home appliances require insect repellent steels that work to protect household microwave ovens from incurring damage by insects such as fire ants and cockroaches in tropical regions. Thus, POSCO has developed new types of functional steels, coated with an array of organic-inorganic hybrid composites on the steel surface, to cover panels in microwave ovens and refrigerators. The composite solution uses a fine dispersion of hybrid solution with polymeric resin, inorganic and a pyrethroid additive in aqueous media. The hybrid composite solution coats the steel surface, by using a roll coater and is cured using an induction curing furnace on both the continuous galvanizing line and the electro-galvanizing line. The new steels were evaluated for quality performances, salt spray test for corrosion resistance and biological performance for both insect repellent and antimicrobial activity. The new steels with organic-inorganic composite coating exhibit extraordinarily biological functionalities, for both insect repellent and antimicrobial activities for short and long term tests. The composite-coating solution and experimental results are discussed and suggest that the molecular level dispersion of insecticide on the coating layer is key to biological functional performances.

• 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.

• 한국기계가공학회지
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• 제13권3호
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• pp.77-82
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• 2014

In this study, we carried out the interrupted cutting of carbon steel for a machine structure (SM45C) with a CVD-coated tool and conducted an ANOVA test and a confidence interval analysis to find factors influence the surface roughness and to obtain a regression equation. We found that factor which mostly affects the surface roughness during interrupted cutting was the feed rate. The cutting speed and depth of the cut only had small effect on the surface roughness. From the result of a multi-regression analysis during an interrupted cutting experiment, we obtained regression equation. Its coefficient of determination was 0.918, indicating that the regression equation was predictable. Compared to continuous cutting, if the feed rate increases, the surface roughness will also increase during interrupted cutting.

• 한국기계가공학회지
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• 제15권4호
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• pp.40-45
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• 2016

Interrupted cutting has different cutting characteristics compared with continuous cutting. In interrupted cutting, the workpiece has a groove that regularly impacts the cutting tool and workpiece. Therefore, tool damage occurs rapidly, and this increases the cutting force and surface roughness. In this study, we performed interrupted cutting of carbon steel for machine structure (SM45C) using a coated carbide tool (TT7100). To predict the cutting force, we analyzed the experimental results with a regression analysis. The results were as follows: We confirmed that the factors affecting the principal force and radial force were cutting speed, depth of cut, and feed rate. From the multi-regression analysis, we deduced regression equations, and their coefficients of determination were 89.6, 89.27, and 28.27 for the principal, radial, and feed forces, respectively. This means that the regression equations were significant for the principal and radial forces but not for the feed force.

• 한국초전도ㆍ저온공학회논문지
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• 제25권4호
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• pp.28-31
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• 2023

This study presents a comprehensive procedure for the low cycle fatigue test of ultrasonically welded (UW) coated conductor (CC) lap-joints. The entire process is examined in detail, from the robust fabrication of the UW REBCO CC joints to the reliability testing under a low number of repeated cycle fatigue conditions. A continuous I_c measurement system enables real-time monitoring of I_c variations throughout the fatigue tests. The study aims to provide a step-by-step procedure that involves joint fabrication, electromechanical property (EMP) tests under uniaxial tension for stress level determination, and subsequent low-cycle fatigue tests. The joints are fabricated using a hybrid method that combines UW with adding In-Sn soldering, achieving a flux-free hybrid welding approach (UW-HW flux-free). The selected conditions for the low cycle fatigue tests include a stress ratio of R=0.1 and a frequency of 0.02 Hz. The results reveal some insights into the fatigue behavior, irreversible changes, and cumulative damage in the CC joints.

• 한국생산제조학회지
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• 제22권4호
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• pp.665-672
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• 2013

With the development of advanced processing technology, laser processing systems, which require high-quality precision processing, have attracted considerable attention. Although laser equipment is expensive, it enables quick processing and less deformation of materials. This technology is often applied to secondary batteries, which has thus farinvolved the use of argon tungsten inert gas (TIG) welding. However, the welding characteristics of argon TIG welding are not yet good, and a laser is used for welding to address this problem. In this study, lap-joint welding was conducted, and the desired welding characteristics were obtained when the laser power was 1800W and the laser beam travel speed was 1.8 m/min. Lap-joint welding was conducted on Ni-coated SS41. Two cases were compared. No pores were observed in the Ni-coated SS41 lap-joint welding part, and cracks appeared from the lap-joints. Moreover, the pole rod and tap were welded together in a T-joint form to improve the output of the secondary battery. T-joint laser welding showed better welding characteristics than TIG welding.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권5호
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• pp.1-10
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• 2015

FeS, as a natural reduced iron mineral, has been recognized to be a viable reactive material for As(III) sequestration in natural and engineered systems. In this study, FeS-coated sand packed columns were tested to evaluate the As(III) removal capacities under anaerobic conditions at pH 5, 7 and 9. The column obtained As(III) removal capacity was then compared with the capacity result obtained from batch reactors. In the comparison, two different approaches were used. The first approach was used the total As(III) removal capacity which method was proved to be useful for interpreting pH 5 system. The second approach was used to consider sorption non-linearity and proved to be useful for interpreting the pH 9. The results demonstrated that a mechanistic understanding of the different removal processes at different pH conditions is important to interpret the column experimental results. At pH 5, where the precipitation of arsenic sulfide plays the major role in the removal of arsenic, the column shows a greater removal efficiency than the batch system due to the continuous dissolution of sulfide and precipitation of arsenic sulfide. At pH 9, where adsorption mainly governs the arsenic removal, the sorption nonlinearity should be considered in the estimation of the column capacity. This study highlighted the importance of understanding reaction mechanism to predict column performance using batch-obtained experimental results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.282-283
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• 2005

Ion beam assisted deposition(IBAD) technique was used to produce biaxially textured polycrystalline MgO thin films for high critical current YBCO coated conductor. Hastelloy tapes were continuous electropolished with very smooth surface for IBAD-MgO deposition, RMS roughness of Hastelloy tape values below 2 nm and local slope of less than $1^{\circ}$. After the polishing of the tape an amorphous $Y_2O_3$ and $Al_2O_3$ are deposited Biaxially textured MgO was deposited on amorphous layer bye-beam evaporation with a simultaneous bombardment of high energy ions. We had developed the RHEED to measure in-situ biaxial texture of film surface as thin as tens angstrom. And also ex-situ characterization of buffer layers was studied using XRD and SEM. The full-width at half maximum(FWHM) out of plane texture of IBAD-MgO template is $4^{\circ}$.