• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1222-1227
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• 2003

Pitting wear is a dominant form of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In this study, stress intensity factors, $K_{I}$ and $K_{II}$, were calculated for a surface crack in a polyethylene - CoCr - bone system under the rolling and/or sliding contact pressures. Crack length and load location were considered in determination of probable crack propagation mechanisms and fracture modes. Positive $K_{I}$ values were obtained for shorter cracks in rolling contact and for all crack lengths when the sliding load was apart from the crack. $K_{II}$, was the greatest when the load was directly adjacent to the crack $(g/a={\pm}1)$. Sliding friction caused a substantial increase of both $K_{I}^{max}$ and $K_{II}^{max}$. The effective Mode I stress intensity factors, $K_{eff}$, were the greatest at $g/a={\pm}1$, showing the significance of high shear stresses generated by loads adjacent to surface cracks. Such behavior of $K_{eff}$ suggests mechanisms for surface pitting by which surface cracks may propagate along their original plane under repeated rolling or sliding contact.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.68-74
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• 2015

Time domain response analysis for vibro-impact nonlinear behavior of multi-span tube with loose supports was performed using commercial FEA code and user subroutine. Support geometry of multi-span tube with a finite gap is realistically modeled by analytical rigid surface. Model of hydrodynamic force is based on the Qusai-steady model which accounts for the inclined angle of relative flow velocity and time delay between flow force and resulting tube motion. During tube vibration from flow loading, impact and friction at the support location is simulated using commercial FEA code with master slave contact algorithm. Analysis results has reasonable agreement with those of references and test experience. Plan of further refinement of analysis model and future test verification is briefly introduced.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.74-82
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• 2010

Fretting damage can be observed in automobile and railway vehicle, fossil and nuclear power plant, aircraft etc. In the present study, railway axle material RSA1 used for evaluation of fretting fatigue life. Plain and fretting fatigue tests were carried out using rotary bending fatigue tester with proving ring and bridge type contact pad. Through these test, the following results are obtained: 1) it is found that the fretting fatigue limit of standard specimen decreased about 37% compared to the plain fatigue limit. 2) The early crack of Shinkansen type specimens initiated in contact area and final fractured below samp=214 MPa. 3) The early crack of all TGV type specimens initiated in rounded area and fractured. 4) Tire tracks and rubbed scars were observed in the oblique crack region and fatigue crack growth region of fracture surface. 5) The wear debris is observed on the contact surface, and oblique cracks at an earlier stage are initiated in contact area. These results can be used as useful data in a structural integrity evaluation of railway axle.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.17-18
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• 2006

Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is 1400W of the laser power, 0.8m/min, 0.9m/min of welding speed and $4{\ell}$ in of pressure for shielding gas.

• 한국정밀공학회지
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• 제27권2호
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• pp.102-108
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• 2010

Recently, carbon fiber reinforced plastic(CFRP) composite materials have been widely used in various fields of engineering because of its advanced properties. Also, CFRP composite materials offer new design flexibilities, corrosion and wear resistance, low thermal conductivity and increased fatigue life. However CFRP composite materials are susceptible to impact damage due to their lack of through-thickness reinforcement and it causes large drops in the load-carrying capacity of a structure. Therefore, the impact damage behavior and subsequently load-carrying capacity of impacted composite materials deserve careful investigation. In this study, the residual strength and impact characteristics of plain-woven CFRP composites with impact damage are investigated under axial tensile test. By using obtained residual strength and Tan-Cheng failure criterion, residual strength of CFRP laminate with arbitrary fiber angle were evaluated.

• Journal of Biosystems Engineering
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• 제18권1호
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• pp.15-20
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• 1993

Wearness has been a major failure criterion in Korean-made rotary blade. However, few studies have been conducted to improve it. In this study, the fundamental data obtained from the measurement of wearness and failure of rotary blade were analyzed to provide a guideline for the design of rotary blades. For the straight part(about 20-23 em from bolt hole) from the bolt hole to bending point of rotary blade, modifications were proposed for improvements, however, for the portion from bending point to tip was made no design recommendations because the failure behavior of that portion was difficult to analyze with the experimental data. The results are summarized as follows. 1. The current V-shape section has to be moved about 5 em toward the bending point of rotary blade. 2. The section modulus at the portion about 5-7 em distant from bolt hole has to be increased about 15-20 %. 3. The V-shape section has to be changed into U-shape to reduce the on account of recieving initial stress in blades. 4. The radius of curvature of the neck(the portion about 5-7 cm apart from bolt hole) has to be made larger to decrease the stress concentration.

• 한국의류학회지
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• 제16권2호
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• pp.227-235
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• 1992

The purpose of this study was to identify the variables influential on Normative Clothing Conformity, Identificational Clothing Conformity, Clothing Anticonformity, and Clothing Independence. Four clothing-related variables (importance of clothing, confidence of clothing, recognition of clothing norm, and perceived risk of clothing), two personality variables (confer-mistic character and self-esteem) and six demographic variable (sex, age, years of education, job, income, and length of career) were included in the analysis. The responses of 714 fulltime employeed subjects from four different cities were analyzed. Business wear was used as the situational stimulus. As the results, career people conformed more identificationally when they felt clothing was important, had conformistic character, had low self-esteem, and felt psychological risk of clothing. They conformed more normatively when they felt social risk of clothing, recognized the clothing norms of the fim, had confoirnistic character, and recognized the clothing norms of the society. They anticonformed more when they felt clothing was important, were female, did not have conformistic character, had confidence of clothing, and felt less performance risk of clothing. And they acted more independently in clothing behavior when they had confidence of clothing, did not have conformistic character, felt peformance risk of clothing, and felt less social risk of clothing.

• 한국의류학회지
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• 제38권5호
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• pp.743-754
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• 2014

This study identified the internal motives for the purchase behavior of Korean male consumers in multi-brand fashion stores by conducting in-depth interviews with 8 men in their 20s and 30s. All respondents had significant experience with this type of store. Data were analyzed in an inductive way and compared with Bohemianism to interpret and described the results as a recent phenomenon of men's fashion. The five internal motives were extracted from analysis: the pursuit of freedom of expression, the counter-cultural resistance to department stores and domestic fashion brands, which tend to copy designs from international brands, the pursuit of mobility and adventure for trying to search and wear a new fashion style, the pursuit of pleasure through store experience, and the pursuit of artistic value by considering goods purchased in multi-brand fashion stores as artistic and cultural goods.

• 한국의류학회지
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• 제41권4호
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• pp.741-751
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• 2017

Adolescent girls experience significant breast growth is a significant secondary sexual characteristic development; their breasts are clearly different from adults' in volume, location and shape. This study was designed to understand brassiere wearing conditions and practices of adolescent girls aged between 15 and 18, as well as to identify problems and solutions so that it can serve as basic guidelines to develop patterns and sizes for adolescent brassieres. This researcher first studied brassiere wearing conditions and size fitness of adolescent girls. We analyzed the 439 collected responses from an online survey. The survey questionnaires encompassed brassiere wearing conditions and practices, brassiere size awareness, brassiere design preference, and brassiere purchase behavior. The survey found that 55.8% of the responders did not accurately understand their brassiere sizes, and those who understood their size showed a higher satisfaction and less discomfort than those who did not. This study found a requirement to educate adolescent girls on how to select and wear the right-sized brassieres. It is also necessary to promote different brassiere designs for adolescent girls' size and body shape.

• 산경연구논집
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• 제5권3호
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• pp.35-43
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• 2014

Purpose - This study aims to identify the reasons behind the conspicuous consumption of Veblen products, viz. fashion designer wear, diamond and gold jewellery, and high-end cars, to examine how conspicuous consumption varies between Aryan and Dravidian cultures. Research design, data, and methodology - The researchers meticulously review the relevant literature, administered a well-structured questionnaire, and conducted personal interviews on various influential factors relating to the consumption of Veblen products. The convenience sampling technique was used to gather data, with a total sample of 200, equally selected from eight cities of both North and South India the collected data was analyzed through ANOVA and Z-Proportion tests. Results - Indian consumers' conspicuous consumption significantly varies among the Veblen products selected for the study, between the Aryan and Dravidian cultures. Regarding conspicuous consumption of branded accessories, 65 percent of Aryan culture Indians responded positively as against only 45 percent of the Dravidian culture Indians. Conclusions - This ingenious study proffers valuable insights about the conspicuous buying behavior of affluent class consumers in India, which are lucrative for both the corporate sector and academia.