• Tribology and Lubricants
• /
• v.36 no.3
• /
• pp.133-138
• /
• 2020

In this paper, we present an experimental investigation of the friction coefficient and wear area change of carbon/epoxy and E-glass/epoxy composites depending on the fiber direction (0°/90°). We compared the results of the case where the sliding direction is parallel to the fiber direction (0°) with that of the case where it is perpendicular to the fiber direction (90°). The ball-on-plate wear test equipment was used to cause wear in both directions. Two types of specimens were prepared with thicknesses of 3 mm-one made of carbon fiber reinforced plastic composite (CFRP) and the other of glass fiber reinforced plastic composite (GFRP). A normal force of 20 N was applied to the specimen and the sliding speed was 10 mm/s and the sliding distance was set to 20 m to perform the wear test. The CFRP demonstrates superior tribological characteristics compared to the GFRP. This outcome is attributed to graphitization of carbon, which serves as solid lubricating particles. In addition, both CFRP and GFRP are worn more in the 90° direction than in the 0° direction. This is due to the greater occurrence of fiber breakage and separation in the 90° direction than in the 0° direction. This study is expected to be utilized as basic data for understanding the friction and wear characteristics of CFRP and GFRP composites along the fiber direction and to apply the appropriate material.

• Tribology and Lubricants
• /
• v.36 no.2
• /
• pp.88-95
• /
• 2020

In this study, we investigate the mechanical properties of high manganese steel, and the friction and wear characteristics of brake friction material containing this steel, for passenger car application, with the aim of replacing copper and copper alloys whose usage is expected to be restricted in the future. These steels are prepared using a vacuum induction melting furnace to produce binary and ternary alloys. The hardness and tensile strength of the high manganese steel decrease and the elongation increases with increase in manganese content. This material exhibits high values of hardness, tensile strength, and elongation; these properties are similar to those of 7-3 brass used in conventional friction materials. We fabricate high manganese steel fibers to prepare test pad specimens, and evaluate the friction and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The brake pad material is found to have excellent friction stability in comparison with conventional friction materials that use 7-3 brass fibers; particularly, the friction stability at high temperature is significantly improved. Additionally, we evaluate the wear using a wear test method that simulates the braking conditions in Europe. It is found that the amount of wear of the brake pad is the same as that in the case of the conventional friction material, and that the amount of wear of the cast iron disc is reduced by approximately 10. The high manganese steel is expected to be useful in the development of eco-friendly, copper-free friction material.

• Journal of Fashion Business
• /
• v.4 no.2
• /
• pp.51-67
• /
• 2000

The purpose of the study was to investigate general characteristics of brand images of men's wear manufacturers and differences in their brand images according to characteristics of their brands and their merchandise. Thus, this study was to be an exploratory study to search apparel niche-market in men's wear market for the marketers by exploring trends of brand images of men's wear manufacturers. The questionnaire consisted of questions on brand images and characteristics of men's wear manufacturers and their merchandise. The subjects were to evaluate their brand images and rated on 5 point Likert-type scales of 36 adjectives. For the survey, the subjects were 100 employees (62 merchandisers, and 24 designers, etc.) who are employed by men's wear manufacturers which have national brands, designer brands, license brands, import brands or private brands. The SAS PC+ package was used to calculate factor analysis, mean, ttest, ANOVA, Duncan's test, and Tukey's test. The results from the study were as follows: 1) High scores of mean of brand images were simple, prestigious, mannish, and dynamic. 2) The brand images of men’s wear manufacturers were divided into 10 factors which explain 73.91% of the whole image. 3) There were significant differences in brand images according to types of brands, price lines of merchandise and ages of target consumers. 4) There were significant differences in brand images according to categories of apparel (suits vs. casual clothing), types of suits, and types of casual clothing. 5) There were significant correlations between brand images, such as simple image to conservative image, prestigious image and chic image, prestigious image to conservative image, chic image and simple image, etc.

• Journal of Fashion Business
• /
• v.3 no.4
• /
• pp.93-101
• /
• 1999

The purpose of this study is to provide for the basic data useful to the effective production and thereby, help them improve their apparel life. For this purpose, 180 Korean mothers who bring up from newborns to fouryear-old babies were sampled to survey their practices of purchasing the infant's wear and positively identify the factors affecting the practices. Data is processed by a computer(SAS) and analyzed by using frequency, percentage, $\chi^2$-test, Duncan's Multiple Range test. The main results of this study are as follows; 1. The mothers tend to gather the information from the items displayed(50.6%) in the stores. The criteria for purchasing considerably depends on the 2. The places of purchasing on which the mothers rely most for infant's wear are department stores(35.2%) and stores nearby their house(28.5%). The frequency of infant's wear depend on the change of season and necessity. 3. It had been disclosed that the brand favored most by the mothers is AGABANG(48.6%). The most influential factors for the popularity of brands are Design(53.1%). The most important reference affecting the mother's choice of infant's wear is size(51.1%) followed by functionality and price(26.7%). After the purchase, mothers are discontent with the high prices of infant's wear. In all, it has been found through this study that the behavior of number in purchasing infant's wear was influenced by many external factors. Therefore, manufacturers and retailers should manufcture and sell products that are of the highest quality. This must be their utmost concern for the satisfaction of their customers.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.117-117
• /
• 2016

Total ankle replacement (TAR) is a visible option in the surgical treatment of degenerative or inflammatory diseases of ankle joint. it is attributed to the current TAR which has improvements in surgical technique, uncemented implant fixation and minimally constrained articulation. In the clinical result, they can show promised surgical result when compared to earlier attempts in TAR. However, TAR is still not as successful as total knee replacement (TKR) or total hip replacement (THR), it needs to be note that there are limitations in concerning of long term performance of TAR, the high failure rate still associated with wear of the PE (polyethylene) component that has related with their material property and surface roughness. The aim of this study was to introduce the tribology characteristics of total ankle joint prosthesis with one of TDR model which was fabricated to try multi-axis wear test as a region of motion in ankle joint. The wear specimen of TDR was prepared with Ti-6Al-4V alloy and UHMWPE (ultra-high molecular weight polyethylene) for tibia-talus and bearing component, respectively. A wear test was carried out using a Force 5 (AMTI, Massachusetts, US) wear simulator which can be allowed to move in three axis to flexion-extension ($+3^{\circ}{\sim}-6^{\circ}$), internal-external axial rotation (${\pm}5^{\circ}$), as well as sinusoidal compressive load (1.6 kN, R=10). All tests were performed following standard ISO 14243, wear rate was calculated with weight loss of UHMWPE bearing while the specimen has tested at certain cycles. As based on the preliminary results, wear rate of UHMWPE bearing was $7.9{\times}10^{-6}mg/cycles$ ($R^2=0.86$), calculated loss weight until $10^7cycles$ was 79 mg, respectively.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.1
• /
• pp.43-52
• /
• 2016

PURPOSE. This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS. There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P<.05). RESULTS. The Leucite group ($2.670{\pm}1.471mm^3$) showed the greatest amount of antagonist tooth wear, followed by in decreasing order by the Lithium ($2.042{\pm}0.696mm^3$), Zirconia ($1.426{\pm}0.477mm^3$), and Steel groups ($0.397{\pm}0.192mm^3$). Mean volume losses in the Leucite and Lithium groups were significantly greater than in the Steel group (P<.05). No significant difference was observed between mean volume losses in the Zirconia and Steel groups (P>.05). CONCLUSION. Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia.

• Tribology and Lubricants
• /
• v.38 no.4
• /
• pp.136-142
• /
• 2022

This paper investigates the enhanced wear performance of a CrAl coated accident tolerant fuel (ATF) cladding. In the wake of the Fukushima accident, extensive research on ATF with respect to improving the oxidation resistance of cladding materials is ongoing. Since coated Zr claddings can be applied without major changes to the criteria for reactor core design, many researchers are studying coatings for claddings. To improve the quality of the CrAl coating layer, optimization of the manufacturing process is imperative. This study employs arc ion plating to obtain improved CrAl coated claddings using CrAl binary alloy targets through an improved coating method. Surface roughness and adhesion are improved, and droplets are reduced. Furthermore, the coated layer has a dense and fine microstructure. In scratch tests, all the tested CrAl coated claddings exhibit a superior resistance compared to the Zr cladding. In a fretting wear test, the wear volume of the CrAl coated claddings is smaller compared to the Zr cladding. Furthermore, the coated cladding manufactured through the improved process exhibits better wear resistance than other CrAl coated claddings. Based on these results, we suggest that fine microstructure is attributed to a mechanically and microstructurally robust CrAl coating layer, which enhances wear resistance.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.20 no.3
• /
• pp.129-136
• /
• 2007

Purpose: We intended to observe the usefulness of far-infrared radiation functional under inner-wear for dysmenorrhea. Methods: We introduced far-infrared radiation functional under inner-wear to women in childbearing-age by internet portal site. Then, we preliminarily examined dysmenorrhea severity by VAS(visual analogue scale) questionnaire to women interested in far-infrared radiation functional under inner-wear. We selected women scored 5 and above of 10 measurement VAS score. Finally, 121 women were the subject of study and used far-infrared radiation functional under inner-wear for one menstrual cycle. Before and after use of far-infrared radiation functional under inner-wear, we conducted a questionnaire survey of dysmenorrhea severity by VAS. After that, we compared VAS score before and after use. Also, we studied correlation between frequency of far-infrared radiation functional under inner-wear use and ${\Delta}VAS$(VAS score before use minus VAS score after use). For statistics, we used Paired samples test and Spearman's rho correlations, SPSS 13.0 for windows. Results: Before and after use of far-infrared radiation functional under inner-wear, VAS score means were different. Frequency of far-infrared radiation functional under inner-wear use was correlated to ${\Delta}VAS$. Statistically they showed significant result (p<0.05>. Conclusion: The results showed that dysmenorrhea severity by VAS decreased after far-infrared radiation functional under inner-wear use. As frequency of use increased, ${\Delta}VAS$ increased. So we can consider far-infrared radiation functional under inner-wear effects dysmenorrhea severity.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.722-727
• /
• 2004

This paper includes the comparative study between Cr plating and nitriding process with an aim at improving corrosion, wear and maintainability for KNR(Korean Next Generation Rifle) 5.56mm barrel. The endurance test was conducted to compare the performance of standard barrel, Cr plating barrel and nitriding barrel. Main activities are described as follows; optimal Cr plating and nitriding process set-up for KNR 5.56mm barrel; durability test of each barrel(20,000 rounds); salt water immersion test; dispersion, initial velocity, inner diameter data acquisition. According to the results of this firing test, Cr plating barrel is superior to standard barrel and nitriding barrel in view of corrosion, wear and maintainability

• Journal of the Korean institute of surface engineering
• /
• v.47 no.1
• /
• pp.13-19
• /
• 2014

The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, ion nitriding, DLC coated, DLC coated after nitriding for 3 hrs and 6 hrs were investigated to evaluate the beneficial effect for plastic mold steel. Micro Vickers hardness tester was used to estimate nitriding depth from the hardness profile and to measure hardness on the surface. Elastic modulus and residual stress were measured by a nanoindentator. Scratch test and SP (small ball punch test) were utilized to assess the adhesive strength of DLC coating. The depth of nitriding layer was measured as $50{\mu}m$ for the condition of 3 hrs nitriding and $90{\mu}m$ for that of 6 hrs nitriding. Hardness, elastic modulus, residual stress of DLC coating were 20.37 GPa, 162.78 GPa and -1456 MPa respectively. Residual stress on the surface of DLC coating after nitriding could increase to -3914 MPa by introducing nitriding before DLC coating. During the 'Ball-On-Disc' test ${\gamma}^{\prime}$ particles pulled out from the surface of nitrized layer tend to enhance abrasive wear mode since the fraction of ${\gamma}^{\prime}$ (Fe4N) in ion-nitrized layer is known to increases with nitriding time. Thus the specific wear rate of the nitriding layer increased. Comparing with nitriding the specific wear rate in work piece disc as well as ball decreased prominently in DLC coating due to the remarkable reduction in friction coefficient.