• Elastomers and Composites
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• v.41 no.3
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• pp.194-204
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• 2006

The effects of the particle size and the structure of carbon blacks on the friction and the wear behavior of filled natural rubber were investigated in this study. The particle size and the structure of carbon black had a significant effect on the wear rates and the worn surface pattern, and the effect of them on abrasion resistance should be considered for the optimum design of desired wear properties. Ten carbon blacks with various sizes and structures are mixed with natural rubber in order to investigate the effects on the wear rate ($W_R$). The friction and the wear behavior were examined by self-made blade type friction-wear abrader, and the ,elation with characteristic parameter (${\psi}=\sqrt{{N_2^2}+{DBP^2}}$), obtained from the particle size and the structure, was studied. The wear rate ($W_R$) had a Power Law relation with the frictional work ($W_f$) and it was inversely proportional to the characteristic parameter of carbon black. It means that smaller particle size and better structure development of carbon black resulted in improved abrasion resistance.

• Journal of Fashion Business
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• v.13 no.2
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• pp.78-86
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• 2009

When scouring and contraction finishing at $90^{\circ}C$ using Relaxer or Rotary Washer contraction and weight loss ratio in warp and weft directions were excellent. Also surface state of fabric after drying or sanding treatment was excellent without crease. Low melting polyester fabric showed a complete melting bond by heat setting(P/S) at above $160^{\circ}C$. The alkali hydrolysis reaction of polyester showed the breakpoint in the weight loss behavior test, polyester yarn showed a breakpoint ranging from 25% to 28%. This is due to the difference of the hydrolysis rate between regular polyester and soluble polyester. Initially the soluble polyester was eluted and micro-fibrillized 5 times faster than a regular polyester. At a later time, a regular polyester was reduced weight to impart a proper flexibility and drape property to the fabric. As a result of surface sanding finishing, the surface of interior fabric showed a surface state most stabilized when using Mesh No. 220 in mono 0.2d after elution finishing. When the rotation direction of sanding roller was pro-, pro-, pro-, and retro-direction, a directional effect of tuft was not shown, a writing effect as suede was exhibited and a surface state was even. Sublimation fastness was 3-4 class for polyester and 2-4 class for nylon. Light fastness 3-4 class after lapse of 100 hours and 2-4 class after lapse of 160 hours. Abrasion fastness was 3-4 class on wet and 4-5 class on dry Laundry fastness was 2-4 class. As such, the abrasion fastness is slightly reduced upon wetting and the use thereof for interior is excellent, whereas laundry fastness is slightly lowered.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.51.2-51.2
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• 2011

A novel electrospun nanofiber membrane was fabricated using combined poly (vinylphosphonic acid) (PVPA) and polyvinyl alcohol (PVA) intended for bone tissue engineering applications. PVPA is a proton-conducting polymer used as primer for bone implants and dental cements to prevent corrosion and brush abrasion. The phosphonate groups of PVPA have the ability to crosslink and attach itself to the hydroxyapatite surface facilitating faster integration of the biomaterial to the bone matrix. PVA was combined with PVPA to provide hydrophilicity, biocompatibility and improve its spinnability. To improve its mechanical strength, PVPA/PVA and neat PVA mixtures were combined to produce a multilayer scaffold. The physical and chemical properties of the of the fabricated matrix was investigated by SEM and TEM morphological analyses, tensile strength test, XRD, FT-IR spectra, swelling behavior and biodegradation rates, porosity and contact angle measurements. Biocompatibility was also examined in vitro by cytotoxicity and cell proliferation studies with MTT assay and cell adhesion behavior by SEM and confocal microscopy.

• Journal of Welding and Joining
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• v.28 no.4
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• pp.61-66
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• 2010

Silicon nitride is widely used as an engineering ceramics because it has high strength, abrasion resistance and corrosion resistance even at high temperature. However, machining of silicon nitride is difficult due to its high hardness and brittleness. Laser assisted machining(LAM) allows effective cutting using CBN tool by locally heating the cutting part to the softening temperature of YSiAlON using the laser beam. The effect of preheating depending on process parameters were studied to find out the oxidation mechanism. If silicon nitride is sufficiently preheated, the surface is oxidized and $N_2$ gas is formed and escapes from the material, thereby making the cutting process more advantageous. During laser preheating process before machining, high temperature results in strong oxidation which makes the bloating, silicate layers and micro cracks. Using the results of these experiments, preheating characteristics and oxidation behavior were found out.

• Fibers and Polymers
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• v.7 no.3
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• pp.295-304
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• 2006

High-bulk worsted yams with different shrinkable and non-shrinkable acrylic fibers blend ratios are produced and then single jersey weft knitted fabrics with three different structures and loop lengths are constructed. The physical properties of produced yams and compression properties of produced fabrics at eight pressure values (50, 100, 200, 500, 1000, 1500 and $2000 g/cm^2$) were measured using a conventional fabric thickness tester. Then, weft-knitted fabric compression behavior was analyzed using a two parameters model. It is found that at 40 % shrinkable fibre blending ratio the maximum yam bulk, shrinkage, abrasion resistance and minimum yarn strength are obtained. It is also shown that high-bulk acrylic yarn has the highest elongation at 20 % shrinkable fibre blend ratio. The statistical regression analysis revealed that the compression behavior of acrylic weft-knitted fabrics is highly closed to two parameter model proposed for woven fabrics. It is also shown that for weft-knitted structure, there is an incompressible layer (V') which resists against high compression load. Acrylic weft-knitted fabrics with knit-tuck structure exhibit higher compression rigidity and lower softness than the plain and knit-miss structures. In addition, at 20 % shrinkable fibre blend ratio, the high-bulk acrylic weft-knitted fabrics are highly compressible.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.2
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• pp.223-231
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• 1986

During the past decade, the Quick Tool-Life Testing Method has been studied. However, a generalized theory and testing method for the quantitative measurement of tool wear have not been developed yet. Among many factors to affect the tool wear, the flank wear is regarded as a main factor. In this study, the behavior of the flank wear for carbide tool was studied as a preceding step to present a simple method for Quick Tool-Life Testing, and it was found that the flank wear varies in direct proportion to cutting time, and the following general equation is obtained for the flank wear curves with respect to cutting time and velociety.

• Journal of the Korean Society of Combustion
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• v.16 no.1
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• pp.58-65
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• 2011

Thermal spray technology has been used in many industrial application. Especially, thermal spray coating have been employed with the purposes of achieving better resistances in abrasion, heat and corrosion. In the previous studies on the thermal spray coating, thermal spray characteristics from the perspective of combustion engineering have not been investigated sufficiently, while the material characteristics of the coated substrates have been investigated widely. In this study, the effect of spray particles on the flame behavior was experimentally investigated. The amount of the injected particles was measured using the light scattering method and the temperature of the particles was estimated using a two-color method. Various flame-spray interactions were observed and it was found that the high temperature zone near the flame is elongated by particles density. Based on these results, the applicability of the light scattering method and the two-color method was discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1720-1729
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• 2001

Wear characteristics of Nylon and acetal pinions against steel gears for different pitch line velocities was studied with a power circulating gear test rig under unlubricated condition. Specific wear rate was measured as a function of tooth number, module, tooth width and total revolution. The worn tooth surfaces were examined with a profile projector. The Nylon pinion showed lower specific wear rate than the acetal pinion. However, the Nylon pinion was fractured at high tooth loads, whereas the acetal pinion exhibited a steady wear behavior. The wear characteristics of Nylon pinion varied significantly with the Pitch line velocity. Wear occurred most severely at the tooth tip and the region immediately below the pitch line of pinion. The dominant wear mechanisms were adhesion and abrasion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.44-52
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• 2010

Recently, with the high performance and efficiency of machine, there have been required the multi-functions in various machine parts, such as the heat resistance, the abrasion resistance and the stress resistance as well as the strength. Fatigue crack growth tests were carried out to investigate the fatigue characteristics of high carbon steel (SM53C) experienced by high-frequency induction treatment. The influence of high-frequency induction treatment on fatigue limit was experimentally examined with the specialfocus on the variation of surface microstructure and the fatigue crack initiation and propagation through fractography. Also, the shape of hardening depth, hardened structure, hardness, and fatigue-fracture characteristics of SM53C composed by carbon steel are also investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.786-793
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• 2000

Nylon, Polyacetal and PTFE were studied to gain a better understanding of their tribological behavior. Wear tests were conducted with reciprocating motion under dry sliding conditions. Friction coefficient and specific wear rate were measured as a function of sliding distance. The worn surfaces were examined with a Scanning Electron Microscope(SEM). Polyacetal showed lowest specific wear rates and PTFE exhibited lowest friction coefficient. The dominant wear mechanism found were adhesion and abrasion.