• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.170-176
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• 2006

The hard coatings on the polycarbonate plate were performed with the object of substitution the glass in the car to the polycarbonate plate. In this research, (3-glycidoxypropyl)trimethoxysilane (GPTMS), (3-aminopropyl)triethoxysilane (APS), and diethylenetriamine (DETA) were used to prepare the coatings by a sol-gel process. The optimum conditions and formulation to achiere the excellent physical properties of the coating were determined. In the case of using GPTMS and DETA, the smooth coating which had the 2 H class in pencil hardness was formed. In the case of using GPTMS and APS, the coating which had the 2 H class in pencil hardness was also formed. And the coatings with GPTMS and DETA showed an excellent abrasion resistant.

• Journal of Power System Engineering
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• v.16 no.2
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• pp.54-59
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• 2012

In the present study, process optimization for thermal-sprayed Ni-based alloy coating has been performed using Taguchi method and analysis of variance(ANOVA). Ni-based alloy coatings were fabricated by flame spray process on steel substrate, and the hardness test and wear test were performed. Experiments were designed as per Taguchi's L9 orthogonal array and tests were conducted with different Oxygen gas flow, Acetylene gas flow, Powder feed rate and Spray distance. Multi response signal to noise ratio (MRSN) was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi's parametric design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.38-45
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• 2018

Molybdenum flame spray coatings are widely used in industrial fields to enhance the performance of mechanical component parts such as pistons, shafts and clutches. This study investigates the surface characteristics of high tensile brass with molybdenum flame spray treatment using the clutch material for small ship. The surface characteristics after molybdenum flame spray treatment in high tensile brass were quantitatively analyzed for surface composition, coating layer thickness, friction coefficient, abrasion width and phenomenon, micro-hardness, and surface roughness.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.5-12
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• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.281-285
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• 2008

Effective use of available energy sources is of general concern along with the issues of global warming and unstable oil price. As one of the effort to recover waste heat from industrial facilities effectively, researchers have interest in a technology called organic Rankine cycle(ORC), in which the working fluid is some organic liquid instead of water. Known to have poor efficiency already, this old technology is considered to give an innovative solution to utilizing low grade energy sources, by improving the efficiency. Nano fluidics, coatings and the use of additives are the examples of these efforts. In the present study, we present simulated performance of a horizontal tube type condenser geometry. N-hexanr and isopentane are compared to water vapor case under 1 atm and the inet cooling water temperature of $20^{\circ}C$. EES(Engineering Equations Solver) is used for the present work.

• Polymer(Korea)
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• v.31 no.6
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• pp.485-490
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• 2007

Hard coating was made on a polycarbonate plate using a sol-gel process with a melamine derivative and silicates, and examined as potential substitutes for automobile glass. Methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and phenyltriethoxysilane were used to form a coating solution. The coatings on the polycarbonate plate were deposited using a sol-gel process. Poly(methyl methacrylate) was coated on the surface of polycarbonate in order to improve adhesion property. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Adding the melamine derivative to the coating solution, the pencil hardness of the coating was improved. The hardness of a 3H class pencil, excellent abrasion resistance, and surface uniformity were found in the coated polycarbonate surface.

• Corrosion Science and Technology
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• v.10 no.1
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• pp.1-5
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• 2011

The major purpose of the present study is to evaluate the performance of various galvanized (GI) or galvannealed (GA) mild steels and AHSS in stamping applications. Finite Element Analysis (FEA) of selected stamping operations was conducted to estimate the critical pressure boundary conditions that exist in practice. Using this information, laboratory tribotests, e.g. Twist Compression (TCT), Deep Drawing (DDT) and Strip Drawing (SDT) Tests, were developed to evaluate the performance of selected lubricants and die materials/coatings in forming galvanized steels of interest. The sheet materials investigated included mild steels and AHSS (e.g. DP600 GI/GA, DP780 GI/GA, TRIP780 GA and DP980 GI/GA). Experimental results showed that galvanized material resulted in more galling, while galvannealed material showed more powdering and flaking. The surface roughness and chemical composition of galvanized sheet materials affected the severity of galling under the same testing conditions, i.e. lubricants and die materials/coatings. The results of this study helped to determine the critical interface pressure that initiates lubricant failure and galling in stamping selected galvanized sheet materials. Thus, to prevent or postpone the critical interface conditions, the results of this study can be used to select the optimum combination of galvanized sheet, die material, die coating and lubricant for forming structural automotive components.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.475-480
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• 2015

Ultrasonic atomic force microscopy (Ultrasonic-AFM) has been used to investigate the elastic property of the ultra-thin coating layer in a thin-film system. The modified Hertzian theory was applied to predict the contact resonance frequency through accurate theoretical analysis of the dynamic characteristics of the cantilever. We coat 200 nm thick Aluminum and Titanium thin films on the substrate using the DC Magnetron sputtering method. The amplitude and phase of the contact resonance frequency of a vibrating cantilever varies in response to the local stiffness constant. Ultrasonic-AFM images were obtained using the variations in the elastic property of the materials. The morphology of the surface was clearly observed in the Ultrasonic-AFM images, but was barely visible in the topography. This research demonstrates that Ultrasonic-AFM is a promising technique for visualizing the distribution of local stiffness in the nano-scale thin coatings.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.6
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• pp.5-21
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• 2015

The common production methods of nanocellulosic (cellulosic nanofibrils, CNF) materials from wood are being reviewed, together with large scale applications and particularly papermaking applications. The high energy demand for producing CNF has been one particular problem, which has been addressed over the years and can now be considered solved. Another problem was the clogging of homogenizers/microfluidizers, and the different routes to decrease the energy demand. The clogging tendency, related to the flocculation tendency of fibres is discussed in some detail. The most common methods to decrease the energy demand are TEMPO-oxidation, carboxymethylation and mechanical/enzymatic pre-treatments in the order of increased energy demand for delamination. The rheology characteristics of CNF materials, i.e. the high shear viscosity, shear thinning and the thixotropic properties are being illuminated. CNF materials are strength adjuvants that enhance the relative bonded area in paper sheets and, hence increase the sheet density and give an increased strength of the paper, particularly for chemical pulps. At the same time papers obtain a lower light scattering, higher hygroexpansion and decreased air permeability, similar to the effects of beating pulps. The negative effects on drainage by CNF materials must be alleviated through the appropriate use of microparticulate drainage aids. The use of CNF in films and coatings is interesting because CNF films and coatings can provide paper/board with good oxygen barrier properties, particularly at low relative humidities. Some other high volume applications such as concrete, oil recovery applications, automotive body applications and plastic packaging are also briefly discussed.

• Journal of Adhesion and Interface
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• v.7 no.1
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• pp.10-15
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• 2006

The hard coatings on the polycarbonate plate were performed with the object of substitution the glass in the car to the polycarbonate plate. In this research, [3-(methacryloyloxy)propyl]trimethoxysilane were used to prepare the coatings by sol-gel process. Butanol was used as a solvent, HCl was used as a catalyst, and AIBN was used as an initiator. Polycarbonate plate was pretreated with PMMA, and final heating of the coating was done at $130^{\circ}C$ for 6 h. Pencil hardness of the coating was 2 H, abrasion resistance and adhesion of the coating were excellent.