• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2374-2385
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• 1994

SiCw/Al composite material is especially attractive because of their superior specific strength, specific stiffness, corrosion fatigue resistance, creep resistance, and wear resistance compared with the corresponding wrought Al alloy. In this study, Fatigue crack growth behavior and fatigue crack path morphology(FCPM) of SiC whisker reinforced Al 6061 alloy with 25% SiC volume fraction and Al 6061 allay were performed. Result of the fatigue crack growth test sgiwed that fatigue crack growth rate of SiCw/Al 6061 composite was slower than that of Al 6061 matrix therefore it was confirmed that Sic whisker have a excellent fatigue resistance. And Al 6061 matrix had only FCPM perpendicular to loading direction. On the other hand SiCw/Al 6061 composite had three types in fatigue crack path morphology. First type is that both sides FCPM of artificial notch are perpendicular to loading direction. Second type is that a FCPM in artifical notch has slant angle to loading direction and the other side FCPM is perpendicular to loading direction. Third type is that both sides FCPM of notch have slant angle to loading direction. It was considered that this kinds of phenomena were due to non-uniform distribution of SiC whisker and confirmed by SEM observation for fracture mechanism study.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.51-58
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• 2005

The development of the high-efficiency machine-tools equipment and new cutting tool materials with high hardness, heat- and wear-resistance has opened the way to application of high-speed cutting process. The basic argument of using of high-speed cutting processes is the reduction of time and the respective increase of machining productivity. In this sense, the spindle units may be regarded as one of the most important units, directly affecting many parameters of high-speed machining efficiency. One of the possible types of spindle units for high-speed cutting is the air-bearing type. In this paper, we propose the mathematical model of the dynamic behavior of the air-bearing spindle. To provide the high-level of speed capacity and spindle rotation accuracy we need the adequate model of "spindle-bearings" system. This model should consider characteristics of the interactions between system components and environment. To find the working characteristics of spindle unit we should derive the equations of spindle axis movement under the affecting factors, and solve these equations together with equations which describe the behavior of lubricant layer in bearing (bearing stiffness equations). In this paper, the three influence coefficients are introduced, which describe the center of spindle mass displacement, angle of shaft rotation around the axes under the unit force application and that under the unit torque application. These coefficients are operated in the system of differential equations, which describes the spindle axis spatial movement. This system is solved by Runge-Kutta method. Obtained trajectories and amplitude-frequency characteristics were then compared to experimental ones. The analysis shows good agreement between theoretical and experimental results, which confirms that the proposed model of air-bearing spindle is correctis correct

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.80-80
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• 2017

Titanium and its alloys that have a good biocompatibility, corrosion resistance, and mechanical properties such as hardness and wear resistance are widely used in dental and orthopedic implant applications. However, they do not form a chemical bond with bone tissue. Plasma electrolytic oxidation (PEO) that combines the high voltage spark and electro-chemical oxidation is a novel method to form ceramic coatings on light metals such as tita-nium and its alloys. This is an excellent re-producibility and economical, because the size and shape control of the nano-structure is relatively easy. Silicon (Si), manganese (Mn), and magne-sium (Mg) have a useful to bone. Particularly, Si has been found to be essential for normal bone, cartilage growth, and development. Mn influences regulation of bone remodeling be-cause its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. Pre-studies have shown that Mg plays very im-portant roles in essential for normal growth and metabolism of skeletal tissue in verte-brates and can be detected as minor constitu-ents in teeth and bone. In this study, Electrochemical behavior of plasma electrolytic oxidized films formed in solution containing Mn, Mg and Si ions were researched using various experimental in-struments. A series of Si-Mn-Mg coatings are produced on Ti dental implant using PEO, with the substitution degree, respectively, at 5 and 10%. The potentiodynamic polarization and AC impedance tests for corrosion behav-iors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to + 2000mV. Also, AC impedance was performed at frequencies anging from 10MHz to 100kHz for corrosion resistance.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.58-63
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• 2007

The relationship between GMA welding conditions and the bead shape of overlay weld was studied by using ${\Phi}1.6mm$ hypo-eutectic metal-cored wire designed for hardfacing against the severe metal-to-metal wear. As the welding voltage increased, the dilution also increased but the sudden drop of dilution was observed at $30{\sim}33V$. It was considered to be due to the decrease of penetration resulting from the change of transfer mode, from short circuit to spray. It was also found that the behavior of penetration with welding current was dependant on the transfer mode. The short circuit mode exerted the penetration to decrease while the spray mode did it to increase with increase of welding current. The former was considered to be responsible for the remarkable decrease in dilution at low welding voltage region. The change of transfer mode also had an effect on the behavior of bead width with welding current but it did not on the bead spreadability defined as W/H ratio. It was considered that the optimal welding conditions for multi-pass overlay welding could be obtained from the bead spreadability suitable for bead lapping and the dilution as low as possible in the spray transfer mode.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.624-635
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• 1990

Analytical study based on linear fracture mechanics was conducted on propagation behavior of inclined surface crack in semi-infinite elastic body. The analytical model was assumed to be inclined surface crack under plane strain condition upon which Hertzian stress was superimposed. Supposing continuous distribution of dislocation and applying Erdogan-Gupta's method to this crack problem, the stress intensity factors $K_{I}$ and $K_{II}$) at the crack-tip were obtained for various Hertzian contact positions. Analytic results have shown that driving force for crack growth is $K_{I}$ for non-lubricated condition and $K_{II}$ for fluid and boundary lubricated condition. The coefficient of friction at the hertzian contact and crack surfaces plays an important role in predicting the direction of crack propagation. It is also found that the maximum effective stress intensity factor exists at cracks of a certain specific length depending on lubricated condition.ion.n.

• Journal of the Korean Society of Clothing and Textiles
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• v.4 no.1_2
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• pp.11-18
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• 1980

This study attempts to discern the purchasing pattern of urban husbands' clothing in Korea. Studies on this subject in other cultures show that wives play lesser role in purchasing activities of their husbands' clothing in the industrial societies rather than in the pre-industrial ones. It would be interesting to know the way selecting and buying husbands' clothing in urban Korea. Specifically questions to be answered include: Who makes the decision in selecting in kinds of husbands' clothing and who buy them? Data for this study has been collected through structured questionaire survey for 606 married women in the City of Seoul including 192 mothers of elementary school students, 58 elementary school teachers, 210 mothers of middle and high school students, 56 mothers of undergraduate students, and 47 college professors. Since most women of our sample are relatively high in educational level and working for various educational institutions, the findings of this study should not be generalized as a general trend of urban Korea. Major findings of this study include: 1) Purchasing husbands' clothing is not entirely wives' domain. The degree of participation on the part of wives in selecting and buying of their husbands' clothing depends upon the kinds of clothings. If it is for such items as underwear, socks, handkerchief, or umbrella, which are relatively easy to choose in terms of size, outlook, and price, more wives do the job. Other- wise, however, husbands more actively participate in selecting and buying their own clothings such as shoes, overcoats, neck tie, and formal wear. 2) In terms of clothing behavior of husbands, it seems to be a general trend that husbands select their clothings, but wives buy them. 3) Variables related to socio-economic status seem to affect the clothing behavior of husbands. Those who more actively participate in selecting and buying their clothings include: husbands whose wives have a job outside thier family, younger in age, middle school or high school graduates rather than college graduate or husbands with far lesser education, and husbands who live in western style houses rether than in traditional Korean houses.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.6
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• pp.1155-1166
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• 2001

The purposes of this research were 1) to identify shopping orientation according to customer's personality type, 2) to examine perceived importance of service and satisfaction of service related to customer's personality type, 3) to find the relationships of evaluation of salesperson's service and re-purchase intention in each of customer's personality types. The data were collected via self-administered questionnaires from 434 female formal wear shoppers. and were analyzed by frequency, factor analysis, ANOVA, Chi-square test, and multiple regression analysis. The results of this study were as follows: Shopping orientations varied according to customer's personality type. E type had stronger Hedonic/self-confidence than I type, F type had higher Depending decision making than T type and P type had higher Quick decision making than J type. And service items satisfied the customers with a certain personality type. E type was satisfied with timely and proper A/S, not forcing to purchase and trustful behavior of salesperson more than I Type was. And also with expertise, individualized care, polite attitude, and merchandising promotion. N type was satisfied with individualized care more than S type was. A service evaluation criterion affected the re-purchase intention for a customer with a certain personality type. Customer's convenience in E. I. S, N, T, F, J types had a significant effect on re-purchase intention. And Expertise/ care in E, N, T, J types had a positive effect on re-purchase intention. also Politeness in E, I, S, N, T, J, P types did. But in only E type, Merchandising promotion affected re-purchase intention.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.1 s.49
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• pp.127-134
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• 2005

This study is to identify the psychological effect of make-up, to examine women's tendency toward make-up and to figure out relationships between their psychological properties and its functions. This study has verified that makeup has a positive effect on their interpersonal relationships, psychological reaction and self- confidence as well as it meets their fundamental aesthetic needs. And further studies about psychological reason why they wear makeup need to be made. Makeup has an effect on their looks and it has a psychological effect of being able to decorate and move their mind. finally, it is anticipated that the study for psychological approach to makeup could contribute on the study for positive makeup treatment.

• Fashion & Textile Research Journal
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• v.21 no.5
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• pp.564-573
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• 2019

Recently, purchasing expensive branded apparel became prevalent among adolescents as they consume conspicuously. People in their adolescence strongly tend to follow peers and are very likely to pay attention to how they wear look to others. Already a good deal of prior research about young people's conspicuous consumption have focused on variables related to these behaviors. The purpose of this study is to examine demographic characteristics of adolescents who show a conspicuous consumption and factors affecting this consumption which is related to peer relations. And we will examine how negative emotions arisen out of relations influence teenagers' conspicuous consumption of branded apparels ultimately. Being out of favor from peers has an effect on anxiety which is negative emotion in association with peer relations. According to the survey, adolescents did conspicuous consumption following others or following trends to get rid of anxiety. Also, if appears to be acting on clothing consumption as a means not to be marginalized. All these findings are expected to be useful information to adolescents to have a better habit of consumption life, and also anticipated to be valuable information for consumer behavior education. The cause of youth's show-off behavior, which is still incomplete in identity formation and immature in choice and judgement, will have to be analyzed and countermeasures taken against it.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.477-481
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• 2008

The secondary hardening and fracture behavior in P/M high speed steels bearing V content of 9 to 10 wt% have been investigated in terms of austenitizing temperature and precipitation behavior. Austenitizing was conducted at 1,100 and $1,175^{\circ}C$ of relatively low and high temperatures. Coarse primary carbides retained after austenitization were mainly V-rich MC type. They give a significant influence on hardeness and toughness, as well as wear resistance. Tempering was performed in the range of $500{\sim}600^{\circ}C$. The peak hardness resulting from the precipitation of the fine MC secondary carbides was observed near 520, irrespective of austenitizing temperature. Aging acceleration(or deceleration) did not occur with increasing austenitizing temperature because it mainly influences contents of V and C of matrix through the dissloution of coarse primary MC containing lots of V and C. The precipitation of secondary MC carbides, which also contain V and C, did not change the aging kinetics itself. In the 10V alloy containing much higher C content, the impact toughness was lower than 9V alloy, because of the larger amount of primary carbide and high hardness.