• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.12
• /
• pp.2121-2133
• /
• 1997

A finite element code is developed for 3-D self-contact problems, using continuum elements with a SRI(Selective Reduced Integration) scheme to prevent locking phenomenon by the incompressibility of rubber. Contact treatment is carried out in two ways : using the displacement constraints in case of rigid contact ; and imposing the same contact forces on two contact boundaries in case of self-contact. The finite element code developed is applied to the deformation analysis of C.V.joint boots which maintain lubrication conditions and protect the C.V.joint assembly from impact and dust. The boot accompanies large rotation depending on the rotation of the wheel axis and leading to the self-contact phenomena of the boot bellows. Since this contact phenomenon causes wear of the product and has great influence on the endurance life of the product, it is indispensable to carry out stress analysis of the rubber boots. In case of self-contact, various methods for determining contact forces have been suggested with an appropriate contact formulation. Especially, the types of penetration in self-contact are modularized to accelerate conputation with a contact algorithm.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.8
• /
• pp.1179-1189
• /
• 2008

The purpose of this study is to investigate the satisfaction of the adolescents' school backpack bag and the important criteria when purchasing for developing comfort and functional backpack. The questionnaire was composed and surveyed with 245 middle school students and the data were analyzed through SPSS 13.0. Purchasing criteria were grouped into 5: practical, shop environment, comfort, aesthetic and maintenance. Satisfaction factors were function/comfort, fashion/aesthetic and durability/A.S. 50.2% of students recognized the inappropriate wearing backpack might cause the deformation of body shape. And the wrong habit of wearing bag was found to affect the body posture of students. Main symptoms caused by wearing it for long time are ‘sweating around shoulder and back' and ‘feeling stiff in shoulders and waist'. Needs arise to develop the bag which could prevent them and to educate students how to wear bags. According to the result from MDS of purchasing criteria, one axis is product vs. environment, and other is functional vs. psychological aspects. According to the result from MDS of bag satisfaction, one axis is function/durability vs. fashion/appearance, and other is gestalt quality vs. part quality. They wanted the improvement in the aspects of shape/design, material, maintenance, comfort and usability of the bags. Specially it is required that we research the adolescent customer-oriented way and develop the new materials or shapes pursuing both shoulder comfort and characteristics.

• The Research Journal of the Costume Culture
• /
• v.26 no.3
• /
• pp.450-470
• /
• 2018

This study examined the risk components and risk types perceived in the context of purchasing decisions of paper fashion products. This study also identified the levels of perceived risk by consumers and the differences between age groups in risk perception. First, qualitative data were collected through a focus group interview with 7 Korean females in their 20s to 50s. The interviewees were presented with two types of paper materials (undyed and dyed Jumchi-Hanji) and products (bags and wallets) made with the papers. The interviewees mentioned 11 risk components which were classified into five types of risks: performance (easily torn/lack of durableness, lint/pilling/wear-out, lack of water-resistant, no washability, and deformation and discoloration over time), social-psychological (old and traditional image), aesthetic (lack of design diversity, unsatisfactory appearance due to repair), financial (expensive price, lack of usability in daily life) and time/convenience (difficulty in handling) risks. Based on the results of the interview, a measurement for evaluating the risk perception of paper fashion products was developed. Second, quantitative data were collected from 64 Korean women in their 20s to 50s using the measurement. Respondents who were presented with the paper materials and the products perceived the performance risk more strongly than the social-psychological risk and aesthetic risk. In addition, differences between age groups were found: younger respondents perceived performance risk and social-psychological risk more strongly than older respondents, but older respondents perceived financial risk more than younger respondents. Based on this study, strategies for the risk reduction of paper fashion products were proposed.

• Journal of Fashion Business
• /
• v.19 no.5
• /
• pp.1-16
• /
• 2015

The appearances and geometry structures of knitted fabrics have important effects on their functions as textile fabrics. Structural design of the woven fabric, prior to the manufacturing processes in the weaving mill, often leads to a similar predictable appearance in the final outcome with the corresponding weave design. The increase of the employment of elastic textile yarns in knitting fabrics for comfort stretch or outdoor sports wear knit products has, however, resulted in difficulties in predicting the final appearance of the knit structure design. Due to the stretchability and exceptional recovery behavior of the elastic yarns such as polyurethane elastomeric yarns, the appearance of the final product often differs from the initial knit design. At textile CAD program for preparing tricot knit designs has been employed in this study to predict the two dimensional appearance of the design. The similarities between the designs and corresponding knit products seem to be acceptable for the two-dimensional textile CAD program in this study. However, when elastomeric yarns are partially employed in the polyester filament tricot product, a considerable amount of departure from the design is apparent due to the constriction and/or deformation of property differences in the elastomeric yarns and polyester filament yarns. Therefore, another purpose of this study is to measure the departure of the final tricot product from the initial tricot design, especially in the case employing elastomeric yarns in the knit structure together with regular polyester filament yarns. For measuring the three-dimensional departure, a 3D scanning system has been used for the mesh reconstruction of the fabric specimen. Hopefully, the result from this study will be used as a guide to modify and improve the current textile CAD program proposed for the two-dimensional simulation of the tricot.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.20 no.4
• /
• pp.117-130
• /
• 2018

As women wear shoes for a long time due to aesthetic elements and working environment, many women experience discomfort and deformation in their feet due to their shoes and the production of comfortable shoes is becoming an important issue. The purpose of this study is to investigate the factors affecting the grip of shoes by foot type, shoe design, and wearing attitude of shoes. Through this, we suggest solutions for foot discomfort due to wearing shoes and help to prevent foot related diseases. The study results are as follows; first, a wide foot, square-type, and high or low arch (hollow foot or flat foot) among foot shapes influenced the fatigue and pain of feet, and big feet over 250mm-long, wide feet, square-type feet, and high-arch feet (hollow foot) had an influence on distortion and side effects. Second, among the characteristics of wearing shoes influencing foot discomfort, the higher the shoe heels were, the narrower the surface covering the feet was (pumps and mule), and the shoes with high front heels and narrow back heel area, the shoe wearer had a higher possibility of experiencing fatigue and pain and even had not only fatigue and pain but also side effects when she wore pointed shoes. Third, a shoe wearer experiences fatigue and pain if she wears shoes for a shorter period of time, stay stood while wearing shoes for a short time, and wears shoes that are bigger or smaller than the actual shoe size. Fourth, fatigue and pain experiencers and distortion and side effects experiencers all responded that they change into other shoes to deal with foot discomfort and that they directly massage their feet.

• Elastomers and Composites
• /
• v.52 no.2
• /
• pp.114-130
• /
• 2017

Enhancing the properties of rubber, such as the tensile strength, modulus, and wear abrasion, by the addition of carbon black and silica as fillers is very important for improving the performance of rubber products. In this review, we summarize the general features of 'the reinforcement of rubber by fillers' and the equations for representing the reinforcement phenomena. The rubber reinforcement was attributed to enhancement of the following: the rubber, bound rubber, formation of networks, and combination between rubber chains and silica followed by entanglement. The reinforcement capability of silica species with different surface and networked states demonstrated the importance of the connection between the silica particles and the rubber chains in achieving high reinforcement. The model involving combination followed by entanglement can provide a plausible explanation of the reinforcement of rubber by carbon black and silica because the combination facilitates the concentration of rubber chains near the filler particles, and entanglement of the rubber chains around the filler particles enforces the resistance against deformation and breakage of rubber compounds, resulting in high reinforcement.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.1
• /
• pp.61-68
• /
• 2010

Purpose: This article attempted to determine the factors affecting the preload and screw loosening. Methods: Available clinical studies from 1981 to 2008 from the PUBMED that presented screw loosening data and review articles regarding screw joint stability were evaluated. Eleven studies dealing the biomechanical principles of the screw mechanics were reviewed. Moreover, the results of our data were included. Results: The frequency of screw loosening was consequently reduced due to the advancement in torque tightening with torque wrench, screw material, coating technique for reducing the frictional force, and thread design, etc. If preload in the screw falls below a critical level, joint stability may be compromised, and the screw joint may fail clinically. The types of fatigue failure of screw were divided to adhesive wear, plastic deformation, and screw fracture. Conclusion: An optimum preload is essential to the success of the implant-abutment complex. To maintain optimum preload, using a torque wrench and re-tightening at recall time were needed.

• Journal of the Korean Institute of Gas
• /
• v.23 no.4
• /
• pp.40-45
• /
• 2019

This paper is a purpose to study the failure example for heavy-duty vehicle fire. The first example, the researcher found the engine over-heating phenomenon causing a coolant leakage by the sealing poor of head-gasket because of D-ring part deformation contacting with cylinder liner top-part and cylinder head. He certified a fire breakout by short transferred to surrounding wiring of air-cleaner. The second example, a brake lining by return fault of break operating S cam causing with much wear of a rear 4 wheel brake lining repeatably was worn by friction. In the long run, it became the cause of fire. The third example, the researcher knew the fire cause was came about the short of wire by overload of tilting motor when the driver tilted up the cap to inspect a engine. Therefore, a heavy-duty fire must minimize the fire occurrence by thorough controlling.