• 소성∙가공
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• 제16권4호
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• pp.299-303
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• 2007

Dry sliding wear behavior of ultra-fine grained(UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

• 한국의류학회지
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• 제30권4호
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• pp.582-594
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• 2006

The purpose of this study were to develop snow-board lower wear with improved functionality. The study consisted of figure out appropriate ease amount of snow-board lower wear and make products by applying it to pattern design. The results of this study were as follows: On the basis of the analysis of snow-board lower wear on market, 2 pieces of experimental snowboard lower wear were designed, produced, and evaluated the patterns of with different ease, and snowboard lower B for experiment was proved to be better. Snowboard lower wear was produced and evaluated for experiment 2 by giving additional ease to specific parts. Therefore experiment 2 was presented pattern, ease, and size of snowboard lower wear with improved functionality. Sizes and ease of snow-board lower wear for presentation. waist circumference - 96.0cm(l6.4cm, 17.1%); hip circumference - 127.0cm(31.3cm, 24.4%); pants length - 112.0cm(9.6cm, 8.6%); crotch length - 90.0cm(26.8cm, 36.4%); thigh circumference - 78.0cm(23.4cm, 30.0%); knee circumference - 62.0cm(24.7cm, 39.8%); turnup circumference - 62.0cm(36.0cm, 58.1%). Above mentioned sizes and ease of lower wear are medium size(M) for male.

• 한국의상디자인학회지
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• 제10권2호
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• pp.179-191
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• 2008

This study investigated Korean image preferences in casual wear of women consumers and the effects of demographic characteristics on Korean image preferences in casual wear. The subjects of the study were 653 women consumers who lived in Seoul. Data were collected during July, 2007. Statistical analyses used in the study were frequency, ANOVA and Duncan test. The results showed that respondents preferred to express Korean image by color in their casual wear. When it comes to specific preferences for pattern, fabric, and color, circular shape was most preferred as pattern, cotton was most preferred as fabric, and white color was most preferred as color. In addition, there were demographic differences in regard to preferences for pattern, fabric, color, and types of casual wear. The results showed that there were differences in age, occupation, income, and residence. For example, in regard to age, there were differences in the preferences for fabric, color, and types of casual wear. The older respondents preferred natural fabrics more while the younger respondents seemed to accept synthetic fabrics in their casual wear. Also, women aged over 40 preferred cotton pants for their casual wear. This study showed that demographic characteristics are important variables in segmenting the preferences of Korean image for casual wear market.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.411-414
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• 2005

It is reported that $\varepsilon$ (HCP) and $\gamma$ (FCC) phases of a Fe-17Mn alloy transform to $\alpha'$ phase, which has BCC structure, under a deformation condition. In this study, we investigated the effect of strain-induced-transformed $\alpha'$ phase on sliding wear of the Fe-17Mn alloy that originally had e and y phases. Wear tests of the materials were carried out using a pin-on-disk wear tester at various loads of 0.5N-50N under a constant sliding speed condition of 0.38m/s against glass $(83\%\;SiO_2)$ beads. The sliding distance and radius were loom and 9 mm, respectively. Wear rate of the Fe-17Mn alloy was calculated by dividing the weight loss, measured to the accuracy of $10^{-5}g$ by the measured specific gravity and sliding distance. Worn surface and wear debris of the specimens were examined using an SEM and XRD. During the wear, $\alpha'$ phase of BCC structure was formed by strain-induced transformation when the applied wear load exceeded critical values. The $\alpha'$ phase formed by the strain induced transformation increased the wear rate of the Fe-17Mn alloy.

• 대한기계학회논문집A
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• 제32권11호
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• pp.924-929
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• 2008

The rate of wear of cam followers in a valve train system is mainly a function of contact stress between the cam and the follower, sliding velocity and hydrodynamic film thickness between the two mating surfaces. The wear or surface fatigue can be reduced by maximizing the elastohydrodynamic film thickness. In this paper, an attempt has been made to estimate the optimal specific film thickness of cam-follower system quantitatively. A general TES polynomial function with real values of exponents is developed and genetic algorithm (GA) is used as optimization techniques for maximizing the minimum specific film thickness. The optimization programs enumerate values of the exponents for synthesis of cam displacement curves. The results show that the minimum film thickness can be increased considerably, e.g. approximately 7% in this paper.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.213-214
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• 2002

WC cemented carbide are used as many die material to improve abration resistance. Mechanical properties of the cemented carbide were influenced by Co content and WC grain size. In this study, effects of Co content and WC grain size of WC cemented carbide on wear were examied. We prepared 13 cemented carbides with different Co content and WC grain size. Wear test was carried out against S45C under dry condition at 98N and 232mm/s. From the results, we found that wear increased with both Co content and WC grain size. Specific wear rate was range $10^{-7}mm^3/Nm$.

• Tribology and Lubricants
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• 제15권1호
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• pp.83-89
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• 1999

The fretting wear behaviour of Zircaloy-4 tube used as the fuel rod cladding in PWR nuclear power plants has been investigated at the different test environment, in light water and in air as a function of slip amplitude, normal load, test duration and frequency. Zircaloy-4 tubes were used for both of oscillating and stationary specimens. A fretting wear tester was designed to be suitable for this fretting test. The wear volume and specific wear rate of Zircaloy-4 tube in water was greater than those in air under various slip amplitude. Delaminates and surface cracks were observed at low slip amplitude and high load of fretting test in water, but the traces of adhesion and plowing were observed at and above 200 Um. The water accelerates the wear of Zircaloy-4 tube at lower slip amplitude in fretting.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.35-41
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• 1999

Friction and wear test was performed for nylon, acetal resin, and PTFE(polytetrafluoroethylene) under reciprocating dry sliding conditions against a steel counterpart. Friction coefficient and specific wear rate were analysed as a function of sliding distance and applied load. The worn surfaces of plate and disc specimens were observed using SEM(Scanning Electron Microscopy). The experimental results show that acetal resin exhibited lowest wear rates whereas PTFE possessed lowest friction coefficient. The prominent wear mechanisms found were adhesion and abrasion.

• Journal of Welding and Joining
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• 제20권3호
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• pp.54-59
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• 2002

Overlays is a treatment of the surface and near-surface regions of a material to allow the surface to perform functions that are distinct from those frictions demanded far the bulk of the material. Welding, thermal spray, quenching, carburizing and nitration have been used as the surface treatment. Especially, weld overlay is a relatively thick layer of filler metal applied to a carbon or low-alloy steel base metal for the purpose of providing a wear resistant surface. In this study, weld overlay was performed by MAG welding on the base metal(SS400) with filler metal which contain composite powders($Cr_3C_2+Mn+Mo+NbC$) and solid wire(JIS-YGW11). Characteristics of hardness and wear resistance on overlays were analyzed by EDS, EPMA, XRD and microstructures. Carbide formations were $M(Cr, Fe)_7C_3$ and NbC phases. And carbide volume fraction, hardness and specific wear resistance of overlays were increased with increasing powder feed rate and decreasing wire fred rate. Hardness and wear resistance were almost proportioned to carbide volume fraction of overlay.

• 한국주조공학회지
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• 제11권6호
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• pp.482-490
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• 1991

This study presents the wear characteristics of Ti alloys (Pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn) fabricated by centrifugal precision casting in an Ohara dental titanium casting machine. It was found that the hardness of the surface region is higher than that of the interior region. It is considered that the oxygen adsorption in the surface region during casting, leads to the interstitial solid solution hardening. Wear resistance incerases in the order of pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn alloys. The interior hardness value increases in the same order. The specific wear rate increases with applied load and increases monotonously with sliding speed. The Fe transfer from the counterpart material was observed on the worn surface of the Ti-5Al-2.5Sn alloy. Oxidative wear occurs at low sliding speeds and mechanical fracture wear occurs at high sliding speeds.