• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.16-21
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• 2005

The cutting characteristics of hardened steel(AISI 52100) by PCBN tools is investigated with respect to cutting force, workpiece surface roughness and tool flank wear by the vision system. Hard Owning is carried out with various cutting conditions; spindle rotational speed, depth of cut and feed rate. Backpropagation neural networks(BPNs) are used for detection of tool wear. The input vectors of neural network comprise of spindle rotational speed, feed rates, vision flank wear, and thrust force signals. The output is the tool wear state which is either usable or failure. The detection of the abnormal states using BPNs achieves $96.8\%$ reliability even when the spindle rotational speed and feedrate are changed.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.3
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• pp.514-523
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• 1998

The purpose of this study was to compare the wear characteristics of Type III Gold Alloy (Degular C : Degussa AG), VMK 95 (Vita Zahnfabrik), Vitadur Alpha (Vita Zahnfabrik), IPS Empress (Ivoclar-Vivadent) and Targis (Ivoclar- Vivadent). Ten samples of each material were abraded against enamel of extracted incisors for 160,000 cycles on the wear machine. The depth of wear scars on enamel was analized with profilometer (Alpha-step 200;Tencor). And the wear of material specimen was determined with micrometer (PB-IB;Mitutoyo Co. Japan). The results obtained were as follows : 1. Type III gold alloy ($2.47{\mu}m$) and Targis ($5.89{\mu}m$) caused less wear of enamel specimens compared to VMK 95 ($75.59{\mu}m$), IPS Empress ($78.60{\mu}m$) and Vitadur Alpha ($78.89{\mu}m$) (p<0.05). 2. The wear of material specimen when opposing enamel was the lowest in type III gold alloy ($3.0{\mu}m$), followed by Targis ($69.8{\mu}m$), IPS Empress ($148.4{\mu}m$). VMK 95 ($298.0{\mu}m$) and Vitadur Alpha ($300.8{\mu}m$ exhibited the most severe wear against enamel (p<0.05).

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.96-103
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• 2002

The objective of this study is to adjust the roll gap fur the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes fur round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental from and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.1
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• pp.56-62
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• 2003

The objective of this study is to adjust the roll gap for the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes for round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1036-1041
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• 1997

The objective of this study is to adjust the roll gap for the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes for round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• The Research Journal of the Costume Culture
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• v.24 no.6
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• pp.788-802
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• 2016

Sportswear transforms itself into a new fashion item to satisfy desires for beauty in addition to having functionality and movability for sports activities. Sportswear is not in fashion just temporarily but comes in various forms along with sociocultural phenomenon that put emphasis on well-being and leisure. This research aims to study the needs of the bikers who ride bicycles or cycles has become a popular outdoor activity, and give suggestions for high functional sports design that can satisfy the needs of the highly demanding taste of athletes. To understand the design development direction and design preference, practical consumer needs were derived through a survey analysis on bike wear purchasing satisfaction and actual wearing state by bike riders. For consumer needs analysis, focus group interview, in-depth interview and questionnaire method were used. Based on analysis of those researches, athleisure bike wears appropriate for urban sports activities were categorized into sports, life, fitness and leisure 4 styles for athleisure bike wear design development. It is believed that this study will contribute to in the category expansion of sports wear market and satisfy the consumer demands for functional and specialized casual bike wears as well as fashion factors optimized to life style of modern people.

• Transactions of Materials Processing
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• v.32 no.5
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• pp.247-254
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• 2023

This study conducted the wear tests on bending punches coated with PVD CrN and examined the surface quality of the product formed by each punch in the forming of uncoated TRIP1180 sheets. The study quantitatively estimated the surface quality of the product by measuring the roughness and imaging the product surface. The correlation between the punch wear depth and the product surface roughness was quantitatively analyzed. The results showed that before failure occurs, the product roughness was comparable with that of the as-received, and the product surface was smooth without scratches and defects. However, after failure, the punch wear is caused by fretting wear mechanism, and a punch whose coating is not completely peeled plows the product surface, resulting in severe scratches with grooves and ridges on the product surface. Severe wear on the punch surface caused by fretting wear can rapidly degrade the product surface quality as it is directly affected by the punch surface condition, and the product surface quality accurately reflects the punch wear condition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2581-2589
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• 2002

In this research, fretting tests were conducted in air to investigate the wear characteristics of fuel cladding materials with the fretting parameters such as normal load, slip amplitude, frequency and the number of cycles. A high frequency fretting wear tester was designed for this experiment by KAERI. After the experiments, the wear volume and the shape of wear contour were measured by the surface roughness tester. Tribologically transformed structures(TTS) were analysed by means of optical and scanning electron microscopes to identify the main wear mechanisms. The results of this study showed that the wear volume were increased with increasing slip amplitude, and the shape of wear contour was transformed V-type to W-type. Also, it was found that the critical slip amplitude was 168${\mu}{\textrm}{m}$. These phenomena mean that wear mechanism transformed partial slip to gross slip to accelerate wear volume. The wear depth increased with an increase of friction coefficient due to increase of normal load and frequency. The fretting wear mechanisms were believed that, after adhesion and surface plastic deformation occurred by relative sliding motion on the contact between two specimens, TTS creation was induced by surface strain hardening and wear debris were detached from the contact surface which were produced by the micro crack propagation and creation.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.217-225
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• 2002

When we use the flowable resin on the primary molars for quick handling, one of the most important property is the wear resistance. This study was performed to compare the wear resistance characteristics of four flowable composite resins [Arabesk flow (group 1), Tetric flow (group 2), Aeliteflow (group 3), Filtek flow (group 4)] to that of one control composite resin [Z100 (group 5)]. Specimen discs(n=10), 10mm wide and 2mm thick, were stored in distilled water at $37^{\circ}C$ for 7 days prior to testing. The specimens were subjected to 50,000 strokes at 2 Hz on the MTS system. During the test, the following parameters were maintained: the lateral excursion at 0.4mm, occlusal force at 2-100N with a force profile in the form of a half sine wave. The measurements of volume loss, depth of wear, and Vicker's hardness number of composite resins, and SEM observations of the polished and abraded surfaces were established. One-way ANOVA and Scheffe's multiple comparison test were employed to detect statistically significant differences among the flowable composite resin groups and the control composite group at P<.05. The following results were obtained: 1. Group 3 showed the least volume loss, while group 4 showed the greatest. The mean volume loss increased in the following order: group 3

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.221-226
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• 2002

One of the serious challenges in developing rotary compressor with HFC refrigerant is the prediction of scuffing times and wear amounts between vane and roller surfaces. In this study, the tribological characteristics of sliding surfaces using vane-roller geometry of rotary compressor were investigated. The sliding tests were carried out under various sliding speeds, normal loads and surface roughness. During the test friction force, wear depth, time to failure and surface temperature were monitored. Because severe wear was occurred on vane surface, TiN coating was applied on sliding surfaces to prolong the wear-life of vane-roller interfaces. From the sliding test it was found that there was the optimum initial surface roughness to break in and to prolong the wear life of sliding surfaces. Depending on the load and speed, the protective layers, which were composed of metallic oxide and organic compound, were formed on sliding surfaces. Those would play an important role in role amounts of friction and wear between miler and vane surfaces.