• Journal of the Korean Ceramic Society
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• v.45 no.8
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• pp.472-476
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• 2008

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film ($0.1{\mu}m$) and gold film ($1-2{\mu}m$) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with $0.1{\mu}m$ titanium film and $1{\mu}m$ gold film showed microstructure of grains of under 100 nm diameter. The external surface of the stainless steel plates deposited with $0.1{\mu}m$ titanium film and $2{\mu}m$ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.

• The korean journal of orthodontics
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• v.43 no.4
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• pp.186-192
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• 2013

Objective: To analyze the fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Methods: Roots of human mandibular central incisors were covered with silicone, mimicking the periodontal ligament, and embedded in polymethylmethacrylate. The specimens (N = 50), with two teeth each, were randomly divided into five groups (n = 10/group) according to the retainer materials: (1) Interlig (E-glass), (2) everStick Ortho (E-glass), (3) DentaPreg Splint (S2-glass), (4) Ribbond (polyethylene), and (5) Quad Cat wire (stainless steel). After the recommended adhesive procedures, the retainers were bonded to the teeth by using flowable composite resin (Tetric Flow). The teeth were subjected to 10,00,000 cyclic loads (8 Hz, 3 - 100 N, $45^{\circ}$ angle, under $37{\pm}3^{\circ}C$ water) at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (${\times}40$ magnification). Data were analyzed by one-way analysis of variance. Results: All the specimens survived the cyclic loading. Their mean debonding forces were not significantly different (p > 0.05). The DentaPreg Splint group (80%) showed the highest incidence of complete adhesive debonding, followed by the Interlig group (60%). The everStick Ortho group (80%) presented predominantly partial adhesive debonding. The Quad Cat wire group (50%) presented overlying composite detachment. Conclusions: Cyclic loading did not cause debonding. The retainers presented similar debonding forces but different failure types. Braided stainless steel wire retainers presented the most repairable failure type.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.7
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• pp.1121-1127
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• 2009

This study presents an eco-friendly and one-step finishing method for modifying fiber property that reduces fiber damage in wool/polyester blend fabrics. Lipase from aspergillus oryzae is used in this experiment. The enzymatic treatment condition is optimized by measuring the relative activity of lipase depending on pH level, temperature, concentration of lipase, and treatment time. The concentration of $CaCl_2$as an activator is determined by the characteristics including whiteness, water contact angle (WCA), and dyeing property. The modified properties of lipase treated fabrics are tested for pill resistance and surface morphology. The results are described as follows: the optimum condions for lipase treatment constitute a pH level of 8.0, treatment temperature of 40$^{\circ}$$_C$, concentration of lipase at 100% (o.w.f), and a treatment time of 90 minutes. $CaCl_2$helps in raising lipase activation, and the optimum concentration is 50mM. The whiteness, wet ability, and pill resistance of lipase treated fabrics improves as compared to the control. The dyeing property of lipase treated fabrics improved by 53.5% after using the one-bath dyeing method. This means that lipase treatment can save time and cost during the dyeing process since lipase treatment modifies wool and polyester fibers. The surface of lipase treated wool fibers do not exhibit any change, however voids and cracks manifest on the surface of lipase treated polyester fibers.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.35-39
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• 2015

Polyvinylchloride (PVC) thin films having a microporous structure could be prepared by using the solubility difference in solvents. PVC thin film with a water contact angle of $150^{\circ}$ or more was obtained from the PVC solution consisting of the mixture of tetrahydrofuran as a solvent and propanol as a non-solvent. In the drying process of dip-coated PVC film, the increase of drying temperature reduced the tendency of roughened surface, which led the decrease of surface hydrophobicity. As the addition of propanol in the solution with 1 wt% PVC increased, the uniformity of surface roughness was improved. In the case of oxygen plasma treatments, even though the surface structure of PVC thin film was not notably changed, the surface property of the film was changed from the super-hydrophobicity to hydrophilicity as a function of the plasma exposing time.

• Transactions of Materials Processing
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• v.22 no.1
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• pp.23-29
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• 2013

In this study, a micro/nano-random-pattern-structure surface was machined by electric discharge machining (EDM) followed by replicating the EDM surface with a silicone elastomer having low energy and greater hydrophobicity. The variation of hydrophobicity was of prime interest and was examined as a function of the surface roughness of the replicated silicone elastomer. The hydrophobicity was evaluated by the water contact angle (WCA) measured on the relevant surface. For the experiments, the original surfaces were machined by die sinking electric discharge machining (DS-EDM) and wire cutting electric discharge machining (WC-EDM). The ranges of surface roughness were Ra $0.8{\sim}19{\mu}m$ for the DS-EDM and Ra $0.5{\sim}4.7{\mu}m$ for the WC-EDM. In order to fabricate a hydrophobic surface, the EDM surfaces were directly replicated using a liquid-state silicone elastomer, which was thermally cured. The measured WCA on the replicated surfaces for DS-EDM was in the range of $115{\sim}130^{\circ}$ and for WC-EDM the WCA was in the range of $123{\sim}150^{\circ}$. Additionally, the dynamic hydrophobicity was evaluated by measuring an advancing and a receding WCA on the replicated silicone elastomer surfaces.

• Membrane Journal
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• v.26 no.6
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• pp.463-469
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• 2016

In this research, a new expectation in enhancing the PES (polyethersulfone) polymer phase inversion membrane performances with nanoparticles is proposed by using ZnO. This paper investigated the synthesis of PES phase inversion membranes including ZnO nanoparticles and evaluates the performance of these mixed matrix membranes. The PES-ZnO mixed matrix membranes were fabricated by phase inversion method using the PES-ZnO-NMP(N-methyl-1-pyrrolidone) casting solutions with low ZnO nanoparticles content of 0.375 wt%. The influence of ZnO nanoparticles on the characteristics of PES-ZnO mixed matrix membranes was investigated with scanning electron microscope observations of membrane cross-sections, contact angle measurements, tensile strength measurements, pure water flux measurements and ultrafiltration experiments of BSA solution. Those results showed that the performance advancements in comparison with the pure PES membrane without ZnO in terms of increasing hydrophilicity as well as reducing membrane fouling by adding ZnO nanoparticles even in low concentration.

• Polymer(Korea)
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• v.34 no.2
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• pp.89-96
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• 2010

Adhesive binders with core-shell structure of organic/organic pair were prepared by emulsion polymerization of acrylic monomers, such as methyl methacrylate(MMA), ethyl acrylate(EA), n-butyl acrylate(BA), and styrene(St). Ammonium persulfate (APS) was used as an water soluble initiator in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). Non-woven fabric and leather were impregnated with the adhesive binder. The surface of the impregnated fabric and leather were treated with plasma technique and then kinetics analysis and mechanical properties were measured. The conversions of the polymerization of core-shell binder (MMA/EA, MMA/BA) were greater than 90%. When the core-shell binder was prepared at equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the impregnated and plasma-treated non-woven/non-woven fabric has the order of MMA/St, EA/BA, BA/MMA, EA/St, and EA/MMA. When the core-shell binder was prepared at non-equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the non-woven fabric/leather has the order of MMA/BA, BA/EA, MMA/EA, St/MMA, and EA/St.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.17-25
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• 2010

We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2007-2013
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• 2017

In order to give hydrophobic surface properties on carbon steel, the fluorinated amorphous carbon films were prepared by using linear 2.45GHz microwave PECVD device. Two different process approaches have been tested. One is direct deposition of a-C:H:F films using admixture of $Ar/CH_4/CF_4$ working gases and the other is surface treatment using $CF_4$ plasma after deposition of a-C:H film with $Ar/CH_4$ binary gas system. $Ar/CF_4$ plasma treated surface with high $CF_4$ gas ratio shows best hydrophobicity and durability of hydrophobicity. Nanometer scale surface roughness seems one of the most important factors for hydrophobicity within our experimental conditions. The properties of a-C:H:F films and $CF_4$ plasma treated a-C:H films were investigated in terms of surface roughness, hardness, microstructure, chemical bonding, atomic bonding structure between carbon and fluorine, adhesion and water contact angle by using atomic force microscopy (AFM), nano-indentation, Raman analysis and X-ray photoelectron spectroscopy (XPS).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.2
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• pp.133-138
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• 2012

The purpose of this study was to examine the correlation between physical properties of dried coacervate films and dry feel for shampoo composition. Simple shampoo compositions were made of two different cationic charge density polymers in the same surfactant compositions. The simple shampoo compositions were diluted with distilled water to make coacervate. Formed coacervate was collected by centrifuge (3,000 rpm, 30 min). Coacervate was coated on the glass plates and dried in drying oven (for 1 h, $50^{\circ}C$) to make the thin film. We carried out an experiment on measurement of contact angle, moisture loss ratio and SEM image analysis of the dried coacervate film. Dry feelings of the shampoos were evaluated by panel using hair tresses. Results show that the properties of dried coacervate films affect the dry feel of the after shampooing.