• Corrosion Science and Technology
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• v.4 no.1
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• pp.23-28
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• 2005

Several plasma-sprayed ceramic coatings with two- and three-layers were characterized and tested for the application of cooling tube coatings of oxygen convert gas recovery system (OG cooling system) in the steel making plant. Thermal cycling tests using a torch heating with compressed air cooling were carried out and characterized before and after the tests. The effects of metallic bond coat as well as ceramic top coat were also studied. Possible failure mechanisms with low carbon steel substrate were assessed in term of microstructure, porosity, bond strength, thermal expansion coefficient, and the phase transformation. Finally, the results of field tests at the OG cooling system are presented and discussed their microstructural degradation. Test results have shown that three-layered coatings perform better than two-layered coatings.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.730-735
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• 1996

The layered perovskite oxide, KSr2Nb3O10, was synthesized. The interlayer potassium cations were readily exchanged by protons in hydrochloric acid solution to give the protonation compound, HSr2Nb3O10·0.5H2O. The intercalation compounds, [NH3(CH2)nNH3]xSr2Nb3O10, were also obtained by acid-base reactions between the protonation compound and organic bases, 1,n-alkyldiamines. The interlayer distances in the intercalation compounds were linearly increased with the increase of the number of carbon (Δc/Δn=1.05 Å) in 1,n-alkyldiamines. The intercalated alkyldiammonium ions formed a paraffin-like monolayer with average tilting angle (θ) of ca. 56°. The intercalation reactions occurred stoichiometrically. The thermal decomposition process of the intercalation compounds showed distinct three steps due to the desorption of hydrated water, the decomposition of organic moiety, and the decomposition of Sr-related compounds.

• Carbon letters
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• v.25
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• pp.43-49
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• 2018

This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

• Journal of the Korean Vacuum Society
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• v.22 no.6
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• pp.277-284
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• 2013

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition system. The Ni layer on the $SiO_2$ substrate was used as a catalyst for the formation of the carbon coils. The characteristics (formation densities, morphologies, and geometries) of the as-grown carbon coils on the substrate with or without the $H_2$ plasma pretreatment process were investigated. By the relatively short time (1 minute) $H_2$ plasma pretreatment on the Ni catalyst layered-substrate prior to the carbon coils synthesis reaction, the dominant formation of the carbon microcoils on the substrate could be achieved. After the relatively long time (30 minutes) $H_2$ plasma pretreatment process, on the other hand, we could obtain the noble-shaped geometrical nanostructures, namely the formation of the numerous carbon nanocoils along the growth of the carbon microcoils. This noble-shaped geometrical nanostructure seemed to play a promising role as the good catalyst support for holding the very tiny Ni catalyst grains.

• Journal of the Korean Ceramic Society
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• v.43 no.10 s.293
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• pp.607-612
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• 2006

In VARTM (Vacuum Assisted Resin Transfer Molding) process, the permeability generally controls the filling time of the resin and it also affects the void characteristics of the fiber composite. In this study, carbon and glass fiber inter-layered hybrid composites (carbon fiber centered stack) with an epoxy matrix were fabricated by VARTM process and evaluated the resin flow and macro void characteristics. The permeability of glass fiber was higher than that of carbon fiber used in this study. Using Darcy's equation, the permeability of hybrid composites could be predicted and experimentally confirmed. After curing, the macro void content of hybrid composites was investigated using image analyzer. The calculated filling time was well agreed with experimental result and the void content was significantly changed in hybrid composites.

• Clean Technology
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• v.7 no.1
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• pp.51-63
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• 2001

In this study, PSA, known as the most economic process, was used to recover $CO_2$ from the power-plant flue gas. Activated carbon and zeolite molecular sieve 13X were used as adsorbent. Activated carbon has been deemed inadequated adsorbent for separating $CO_2$ from the flue gas. However, highly concentrated $CO_2$ could be obtained as a product on the activated carbon adsorbent using the new operating cycle modifying the rinse step. Also, the recovery of $CO_2$ was improved using double-layered adsorption column packed with the activated carbon and the zeolite 13X simultaneously. Adsorption column was filled with the activated carbon in the feed-end side, and the zeolite 13X in the product-end side. The recovery of $CO_2$ increased about 40% with only 25% zeolite, and increased 67% with 50% zeolite at the experimental conditions of 13% $CO_2$ concentration, 10 SLPM flow rate and 2.2 atm adsorption pressure.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.447-450
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• 2006

Hydrogen separation from multi-component mixture gases by the four-bed PSA process was studied experimentally and theoretically using layered bed of activated carbon and zeolited 5A. Effects of the adsorption time, the linear velocity on the process performance were investigated. The adsorption time and linear velocity affected the purity and recovery of the product $H_2$ purity is increases according as the adsorption time and linear velocity decrease; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 50sec adsorption time, 3cm/s linear velocity might be optimal values to obtain more than 99.999% purity and 65% recovery hydrogen.

• Rubber Technology
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• v.12 no.1
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• pp.1-7
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• 2011

Nanotechnology is the fast becoming key technology of the $21^{st}$ century. Due to its fascinating size-dependent properties, it has gained significant important in various sectors. Myths are being formed on the proverbal nanotechnology market, but the reality is the nanotechnology is not a market but a value chain. The chain comprises of - nanomaterials (nanoparticles) and nanointermediates (coatings, compounds, smart fabrics). Elastomer based nanocomposites reinforced with low volume fraction of nanofillers is the first generation nanotechnology products and it has attracted great interest due to their fascinating properties. The incorporation of nanofillers such as nanolayered silicates, carbon nanotubes, nanofibers, metal oxides or silica nanoparticles into elastomers improves significantly their mechanical, thermal, barrier properties, flame retardency etc., Extremely small particle size, high aspect ratio and large interface area yield an excellent improvement of the properties in a wide variety of the materials. Uniform dispersion of the nanofillers is a general prerequisite for achieving desired properties. In this paper, current developments in the area of elastomer based nanocomposites reinforced with layered silicate and carbon nanotube fillers are highlighted.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.234-237
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• 2003

The absorption and the interference shielding of the electromagnetic wave problem have been a very important issue for commercial and military purposes. This study dealt with the simulation reflection loss for electromagnetic absorbing sandwich type structures in X-band(8.2Ghz~12.4GHz). Glass/epoxy composites containing conductive carbon blacks were used for the face sheets and styrofoams were used for the core. Their permittivities in X-band were measured using the transmission line technique. Simulation results of 3-1ayered sandwich type structures showed the reflection loss using the theory about transmission and reflection in a multi-layered medium.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.442-448
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• 1997

An analytical method based on the nonlinear layered finite element method is developed to simulate the load-dsflection behavior of strengthened beams. Beams considered in this study are the ones strengthened either with external steel plate or Carbon Fiber Sheets(CFS) bonded to the overlay soffit. The theoretically obtained load-deflections and strains of the strengthened beams are compared to the corresponding experimental values. Parametric studies are, then. performed using the developed model to investigate the effects of design variables on the flexural behavior of the strengthened beams. Simply supported beams under monotonically increasing loads sre considered exclusively.