• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.3_4
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• pp.539-545
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• 2004

In this study, the effect of washing, bleaching, and abrasion on tactile and the water absorption properties of the split-type Nylon/Polyester (N/P) microfiber pile-knit was investigated under various enduse conditions. We examined the water absorption and surface properties of PET microfiber which will be very useful in the future. We also studied the variations of their performance during usage caused by friction and repeated washing, regard to all kinds of physical, chemical changes which will appear while using those textiles. Progress in further splitting of PET microfiber fabric is observed with increases in the number of washing and bleaching cycles, and treatment temperature. Initial water absorption (%) was increased with progress in splitting, which provided efficient capillary channel. Surface properties were varied with additional splitting by washing and abrasion. Formation of pilling and splitting by abrasion increase surface roughness, diminishing tactile property, and reduced water absorption property. The current results from this study is expected to provide the appropriate washing management guide to consumers, and to inform end-use performance of product to a producer for improving product quality.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.125-131
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• 2002

Surface defects in injection molded parts are due to the unsteady flow of polymer melt which are related to the geometries of cavity and gate, the operational conditions of injection and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for three kinds of PCs which have different molecular weight and structure, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes that are tensile, flexural and impact test specimens with various gate and cavity thicknesses. Through this study we have observed that the formation of surface defect associated with jetting during filling stage in injection molding is strongly related to die swell. This means that the jetting is strongly affected by the elastic property rather than the viscous property in viscoelastic characteristics of molten polymer. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mold design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting and associated surface defects regardless of magnitude of elastic property. It also enlarges process window that can produce steady flow of polymer melt in injection molding.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.04a
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• pp.1-6
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• 2003

In injection molding of an optical disk, a toric lens, etc., their performance depends on the transcription preciseness of fine surface structure of a mold. However, transcription behavior has not been made clear yet, because transcription is made in very short time and the structure is very small. In this paper, transcription properties have been examined, by using V-grooves of various sizes. machined on mold surfaces, and the following results are obtained. (1) Transcription properties have been made clear experimentally and it was found that the mold temperature $T_D$ makes great influence on the transcription property and that compression applying time $t_c$ should be taken more than 2.0s for fine transcription. (2) A mechanical model of transcription process, in consideration with strain recovery due to viscoelastic property of polymer. is proposed. (3) Simulation results agree with experimental ones fairly well. It means that the transcription model is useful for estimation of transcription property in advance of an actual. injection molding.

• Tribology and Lubricants
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• v.21 no.6
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• pp.302-305
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• 2005

Various carbon nanotubes (CNTs) are added into the epoxy matrix as reinforcements to investigate the effect on the wear behavior. Effects to the tribological properties of different loading concentrations and types of surface modification are investigated by using a linear reciprocal wear tester. As increasing the concentration of CNTs shows the reduction of the wear loss. Moreover, surface modified CNTs give better tribological property than as produced CNTs. It is due that the functional groups on the surface of CNTs increase the interfacial bonding between CNTs and epoxy matrix through chemical bonding. Changes in worn surface morphology are observed by optical microscope and SEM to investigate the wear behavior. CNTs in the epoxy matrix near the surface are exposed and it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the CNTs.

• Corrosion Science and Technology
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• v.13 no.5
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• pp.170-177
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• 2014

Polyurethane coating was designed to give a hydrophobic property on its surface by modifying it with hydroxyl terminated polydimethylsiloxane and then effects of surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified polyurethane coating were examined using FT-IR/ATR spectroscopy, contact angle measurement and electrochemical impedance test. As results, the surface of polyurethane coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between polyurethane and modifier by the modification. The phase separation tendency is more appreciable when modified by polydimethylsiloxane with higher content. Water transport behavior of the modified polyurethane coating decreased more in that with higher hydrophobic surface property. The decrease in the impedance modulus ${\mid}Z{\mid}$ at low frequency region in immersion test for polyurethane coatings was associated with the water transport behavior and surface hydrophobic properties of modified polyurethane coatings. The corrosion protectiveness of the modified polyurethane coated carbon steel generally increased with an increase in the modifier content, confirming that corrosion protectiveness of the modified polyurethane coating is well agreed with its water transport behavior.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.3-8
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• 2007

Nonlinear property and contact matter are analyzed about the pipe applied with internal pressure through this study. The weakest part and its safety can be examined. Maximum equivalent stress is shown at the contact surface between bolt and nut. The value of contact stress with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The maximum contact pressure is shown at the clamp corner of the external surface on pipe. The value of contact pressure with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The radial deformation with no pressure is also increased greatly at the middle part of internal surface on pipe. But this maximum deformation on pipe with the pressure of 12MPa is shown at the part far away the support of pipe. This value is increased 5.7 times as large as that value with no pressure. As contact status, the sticking occurs most at the external surface of pipe. It also tends to occur at the contact surface between bolt and nut. At the external surface of pipe, the sticking in case of the pressure of 12MPa occurs more than that in case of no pressure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.1
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• pp.6-9
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• 2010

Surface properties of polytetrafluoroethylene(PTFE) films fabricated by rf-magnetron sputtering system with UV surface treatment were investigated to increase water contact angle for their hydrophobic property. We found that the surface morphology and water contact angles of PTFE film modified as a function of the UV treatment times using UV-irradiation were influenced. The water contact angle of PTFE film with optimized UV treatment time for 15 minute showed a high hydrophobicity compared with the film without any surface treatment. We thought that it was due to the energy change of PTFE surface with an adhesion improvement to the glass surface as a smoothing a rough surface with needle-shape and/or the enhancement of an interface property as a removing some defects on the surface like a cleaning effect.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.89-91
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• 2012

The purpose of this study is to investigate the mechanical property and carbonation resistance of concretes using surface treated lightweight aggregate. In order to evaluate mechanical property and carbonation resistance, slump, compressive strength, and carbonation depth are tested. Slump of concretes using surface treated lightweight aggregate measured 120~125mm, which are lower than slump of NWAC. Compared to compressive strength of NWAC, compressive strength of concretes using surface treated lightweight aggregate showed a level of 82.8~95.9%. In carbonation resistance test, carbonation depth of concretes using surface treated lightweight aggregate measured 10.2~11.3mm, which are lower than carbonation depth of NWAC. As a result, it is found that compressive strength is decreased slightly but carbonation resistance is improved, in case of using surface treated lightweight aggregate.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.1
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• pp.61-70
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• 2001

As important factors determining human sensorial comfort, liquid moisture management and surface properties of heat resistant workwear materials were examined. To figure out liquid moisture management properties of the test materials, absorption capacity, rate of absorption, and evaporation properties were assessed. A modified GATS(Gravimetric Absorbency Testing System) was used to measure the liquid moisture accumulation associated with the wicking of liquid moisture from sweating skin. The GATS procedure measures demand wettability of materials to take up liquid in a direction perpendicular to the fabric surface and it was modified to incorporate a special test cell and cover to assess absorption behavior in the presence of evaporation. Fabric stiffness, smoothness, number and the length of surface fibers, and an estimate of the contact area between the skin and fabric surface were measured to characterize the mechanical and surface properties of the test materials. Also an estimate of the force with which a fabric clings to moist skin was made using as wet-cling index.

• Corrosion Science and Technology
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• v.11 no.1
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• pp.15-19
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• 2012

Both electrogalvanized and hot-dip galvanized steel sheets have been finally produced via organic-inorganic surface coating process on the zinc surface to enhance corrosion resistance and afford additional functional properties. Recently, POSCO has been developed a variety of chromate-free coated steels that are widely used in household, construction and automotive applications. New organic-inorganic hybrid coating solutions as chromate alternatives are comprised of surface modified silicate with silane coupling agent and inorganic corrosion inhibitors as an aqueous formulation. In this paper we have prepared new type of hybrid coatings and evaluated quality performances such as corrosion resistance, spot weldability, thermal tolerance, and paint adhesion property etc. The electrogalvanized steels with these coating solutions exhibit good anti-corrosion property compared to those of chromate coated steels. Detailed components composition of coating solutions and experimental results suggest that strong binding between organic-inorganic hybrid coating layer and zinc surface plays a key role in the advanced quality performances.