• Corrosion Science and Technology
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• v.18 no.5
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• pp.212-219
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• 2019

This paper reviews recent approaches to develop composite polymer-containing coatings by plasma electrolytic oxidation (PEO) using various low-molecular fractions of superdispersed polytetrafluoroethylene (SPTFE). The features of the unique approaches to form the composite polymer-containing coating on the surface of MA8 magnesium alloy were summarized. Improvement in the corrosion and tribological behavior of the polymer-containing coating can be attributed to the morphology and insulating properties of the surface layers and solid lubrication effect of the SPTFE particles. Such multifunctional coatings have high corrosion resistance ($R_p=3.0{\times}10^7{\Omega}cm^2$) and low friction coefficient (0.13) under dry wear conditions. The effect of dispersity and ${\xi}$-potential of the nanoscale materials ($ZrO_2$ and $SiO_2$) used as electrolyte components for the plasma electrolytic oxidation on the composition and properties of the coatings was investigated. Improvement in the protective properties of the coatings with the incorporated nanoparticles was explained by the greater thickness of the protective layer, relatively low porosity, and the presence of narrow non-through pores. The impedance modulus measured at low frequency for the zirconia-containing layer (${\mid}Z{\mid}_{f=0.01Hz}=1.8{\times}10^6{\Omega}{\cdot}cm^2$) was more than one order of magnitude higher than that of the PEO-coating formed in the nanoparticles-free electrolyte (${\mid}Z{\mid}_{f=0.01Hz}=5.4{\times}10^4{\Omega}{\cdot}cm^2$).

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.495-505
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• 2008

With the high proportion of zinc coated steels in body-in-white assembly, newly developed surface roughness textured galvannealed steel sheets have been introduced. In this study, zinc coated and surface roughness textured steel sheets were welded by resistance spot welding to investigate its weldability including electrode wear test. Based on the results of tensile-shear test, nugget diameter changes, and electrode tip growth test, it was clear that both surface roughness textured steels (GA-T and GA-E) showed good weldability. Also, there was no large difference in weldability and electrode wear behavior between GA-T and GA-E steels which have different surface roughness morphology. An analysis of electrode degradation showed Fe and Zn penetration through the electrode tip surface at 2400 welds reached $55{\sim}60{\mu}m$ and $75{\sim}80{\mu}m$, respectively. Therefore, there is no significant effect of surface roughness morphology on spot weldability of surface roughness textured galvannealed steel sheets. However, slight difference in thickness of alloying layers existing on electrode tip was found between GA-T and GA-E steels.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.47-56
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• 2015

In this paper, the Thermal behavior and reliability characteristics of carbon CCL (Copper Claded Layer), which can be used as the core of HDI (High Density Interconnection) PCB (Printed Circuit Board) are evaluated through experiments and numerical analysis using CAE (Computer Aided Engineering) software. For the characterization of the carbon CCL, it is compared with the conventional FR-4 core and Heavy Cu core. From research results, the deformation amount of the flexure strength of PCB is the highest with pitch grade carbon and thermal behavior of PCB is lowest as temperature increases. In addition, TC (Thermal Cycling), LLTS (Liquid-to-Liquid Thermal Shock) and Humidity tests have been applied in the PCB with carbon core and the reliability of PCB with carbon core is confirmed through reliability tests. Also, possibility of uneven surface of the via hole and wear of the drill bit due to the carbon fibers are analyzed. surface of the via hole is uniform, the surface of the drill bit is smooth. Therefore, it is proved that the carbon CCL has the drilling workability of the same level as conventional core material.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.7
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• pp.1038-1049
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• 2009

A hat is an important fashion accessory item for a total fashion coordination and the number of millineries is increasing in the current accessory market. This research provides basic information about the millinery in relation to consumer consumption behavior, preference, and satisfaction with hat products. A survey was conducted among 395 individuals age 20 and over who were quota sampled according to age and gender to investigate the differences between genders and different age groups. The collected data were statistically treated with the SPSS 12.0 program in terms of frequency, percentage, mean, standard error, cross tabulation, t-test, one-way ANOVA, and a Duncan-test. The results are as follows: 1. Respondents wear hats for ornamental purposes regardless of the season. They discard hats when they become out of style 2 to 3 years after the purchase. 2. In general, consumers prefer the baseball cap design among various hat product categories. Achromatic colors were the favorite color tone and the preferred material was woven cloth. 3. Consumers were most satisfied with colors and most dissatisfied with deformation after laundering. 4. There was a significant difference in preferences among the different age groups. Younger consumers were more concerned about individual image and style. Older consumers considered hats as a functional means such as protecting themselves from the sun. 5. There was a significant gender difference. Compared to males, female consumers were more concerned about the quality of sewing and colorfastness than male consumers.

• Journal of the Korea Fashion and Costume Design Association
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• v.7 no.2
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• pp.11-24
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• 2005

The purpose of this study was to obtain and offer useful information on innerwear industry through an analysis of consumer purchasing behavior and preference of their between the 20's and 60's. From 310 questionnaires that were distributed, 310 with usable data were coded for further statistical analysis including descriptive statistics(frequency and chi-square test), by using SPSSWIN 10.0. The results were as follows: The results show that since the surveyed women's purchasing patterns were varied according to their ages it is necessary to develop new items and designs tailored for particular needs and wants of each age group. For those in their 20's, it is suggested that the innerwear design may consider reflecting the trend of the young women nowadays as characterized by a major fashion-led group who regard fashion as a way of expressing themselves and are not hesitant to wear clothing designed to be exposed their body. The innerwear products for women in their 30's and 40's should emphasize on the aspects of customizing and satisfying these women's different lifestyles. The study also reveal that for age groups of the 50's and 60's women these products should be developed in a way to intensify functions of thermal property and absorbency coupled with a classic design rather than daring styles. In conjunction with material developments it is necessary to establish a sizing system for the knitted innerwear products which reflect the specific characteristics of women's body type in their middle-and later years.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.1
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• pp.71-82
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• 2001

In this study, Internet users were separated into 3 groups(clothing shoppers, clothing non-shoppers, non-shoppers). Shopping behavior of clothing shoppers(those who used the internet channel for clothing shopping) and the attitude to internet clothing shopping were examined. And characteristics of clothing shoppers were compared with characteristics of clothing non-shoppers(those who purchased goods except clothing on internet) and non-shoppers(those who purchased nothing on internet). The reason why clothing non-shoppers and non-shoppers didnt purchase clothing on internet was also investigated. Questionaire was used as method of gathering data. Mean, ANOVA, Duncan-test, t-test and $\chi$$^2$-test were used for data analysis. 1. Clothing shoppers considered carefully design, exchange & refund, quality and price and purchased generally T-shirt, underwear, jeans and sports wear. 2. Clothing shoppers thought clothing in internet shopping malls was not various in item, design, color, size and price. But they were satisfied with shopping convenience. 3. Clothing shoppers were more conscious of the shopping cost compared with clothing non-shoppers and non-shoppers Recreational shopping orientations and fashion leader orientations were low in both groups. Self-confidence in connection with clothing purchase were high in each groups, but that of clothing shoppers were relatively higher than clothing non-shoppers and non-shoppers. 4. The reason why clothing non-shoppers and non-shoppers didnt purchase clothing in internet shopping malls was that they wanted to buy after trying on clothing in a store, didnt believe the quality of clothing, didnt need to purchase clothing in internet shopping malls, and worried about exchange & refund.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.503-510
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• 2009

Latex modified concrete (LMC) is a successful polymer-portland cement concretes, which have been developed and used for many years, in overlaying bridge decks and resurfacing industrial floors. The excellent bond strength to substrate, easy application and high resistance to impact, abrasion, wear, aggressive chemicals and freeze-thaw deterioration have made this material used widely. The objective of this study was to determine experimentally the load-deflection response and ultimate strength of reinforced RC beams. The cracking patterns and the mode of failure were observed. Because of excellent bond strength and repairing effects, the RC beams repaired by LMC at compression or tension zone showed over 100% recovery from damaged structures. The RC beams overlaid by LMC showed significant improvement at load carrying capacity as overlay thickness increases. However, the beams repaired of tension zone without shear stirrups almost showed no strengthen effect, and indicated an interfacial failures. The interfacial behavior was estimated by numerical method adopting the concept of shear flow.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.231-239
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• 1999

The microstructure of ceramic composite has been found to be governed by the type and amount of the secondary phase, the sintering aid, and the sintering conditions such as sintering temperature, pressure and holing time. Moreover, tribological properties are strongly dependent on microsturcture of composite and operating conditions. In this study, silicon nitride with various amount of magnesia as a sintering aid were prepared and sintered by a hot pressing (HP) technique. Microstructure, mechanical properties (hardness, strength, and fracture toughness), and tribological properties in different environments of $Si_{3}N_{4}$ (in air, water, and paraffine oil) were investigated as a function of MgO content in $Si_{3}N_{4}$. As increasing the amount of MgO in $Si_{3}N_{4}$, the glassy phase in the grain boundaries enlarged the $\beta$-phase elongated grains, and also degraded the Hertzian contact damage resistance. Tribological behaviors in air was seemed to be determined by fracture toughness of $Si_{3}N_{4}$, and those in water and paraffin oil was seemed to be determined by hardness as well as strength. Since glassy grain-boundary phase (MgO) in $Si_{3}N_{4}$ expected to be reacted with water during sliding, such tribochemical reaction reduced wear. In paraffin oil under a higher applied load, the initial sliding dominated wear rate because of Hertzian contact damage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.329-337
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• 2019

We synthesized potassium titanates having splinter and plate shape and evaluated frictional and wear properties of brake pad using them as reinforcements in friction materials. For splinter-shaped potassium titanates, potassium tetratitanate (K₂O·4TiO₂, PT4) with plate shape was prepared, then K ion of the titanate was leached by acid to make potassium hexatitanate (K₂O·6TiO₂, PT6), which was transformed to splinter-shaped PT6 by thermal treatment at 800℃. Plate-shaped potassium magnesium titanate (K_0.8Mg_0.4Ti_1.6O₄, PMT) was prepared by adding Mg in the potassium titanate using KCl as a flux. Using PT6 and PMT as reinforcements in friction materials of brake pad, we evaluated frictional and wear properties using 1/5-scale dynamometer. According to dynamometer test results, both reinforcements shows similar friction coefficient and fade & recovery behavior to conventional material and plate-shaped PMT exhibits higher wear resistance than splinter-shaped PT6.

• Elastomers and Composites
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• v.46 no.1
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• pp.45-53
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• 2011

The effect of the silane coupling agent, bis(triethoxysilypropyl)tetrasulfide (TESPT), on mechanical properties of a silica-filled NBR compound for oilseal was investigated. Curing behavior and crosslinking density of the compounds were measured using ODR (oscillating disk rheometer) and swelling ratio in toluene. UTM (universal testing machine) and shore A hardness tester were used in order to study the characteristics of mechanical properties of original vulcanizates and aged ones with heated air and ASTM No. 3. oil. Recovery of elasticity which influences the performance and service life of oilseal was investigated by giving bending deformation to vulcanizates in aging condition. After bending aging test, recovery distance was measured and calculated angle of recovery from it. TR (temperature retraction) test was performed on these vulcanizates to determine the low temperature recovery behavior. Wear resistance was measured by Taber type abrasion tester. In addition, SEM was used to characterize the morphology of the worn surface of vulcanizates. The result showed that addition of TESPT into silica-filled compound improves not only compound flow-ability, interaction between NBR and silica and crosslinking density, but also hardness, 100% modulus, recovery of elasticity, wear resistance, heat resistance and ASTM No.3 oil resistance of vulcanizates.