• Tribology and Lubricants
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• v.38 no.1
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• pp.8-14
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• 2022

Amorphous carbon (a-C) has excellent wear resistance and, therefore is used as a coating to protect numerous mechanical components to prolong their lifetimes. Among the a-C coatings, diamond-like carbon (DLC) and DLC-containing silicon (Si-DLC) receive extensive attention owing to their enhanced wear resistance and low frictional characteristics. In this study, the friction and wear characteristics of DLC and Si-DLC coatings are analyzed. For comparative analysis, DLC-coated and Si-DLC-coated vanes are utilized with the counterpart of a roller for the friction tests. Since the lubricated mechanical components are generally vulnerable to wear when a lubricant film does not form properly, friction tests are conducted under boundary lubrication conditions to promote wear. A cylinder-on-cylinder type tribometer is used to perform the friction tests with various normal load conditions. After the friction test, a 3D laser confocal microscope is used for quantifying the wear volume to calculate the wear rate of each specimen. Consequently, the DLC-coated specimen shows a lower coefficient of friction (COF) and wear rate than the specimen without the coating, while the Si-DLC coating shows a higher COF than the bare specimen. The results of this study are expected to contribute to improving the efficiency and reliability of compressors.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.2
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• pp.136-145
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• 1986

The perfect and accurate methods to control the wear are not made clear so far. For this phenomenon only mating surface has been studied. In order to control the wear the essence of it has to be made clear. It is reported that adhesive wear might occure as a result of plastic deformation, the fracture and removal or transfer asperities on close contacting surfaces. On this view point the plastic flow was attempted to compare with fluid or electromagnetic flow. The partial differential equations of equilibrium for the plane strain deformation will make use of the method of characteristics. The characteristic curves or characteristics of the hyperbolic equation coincide with the slip lines by R. Hill's papers. By Hencky's stress equation, it is evident that if P and .phi. are prescribed for a boundary condition then it may be possible to proceed along constant .alpha. and .betha. lines to determine the value of the hydrostatic pressure everywhere in the slip line field net work. A wedge formation mechanism has been considered for an explanation of this matters. The analysis shows that there is a critical value, which depends on the hardness ratio and the shear stress on the interface, for the top angle of asperity is less than this critical value, the asperity can yield plastically despite of being harder than the mating surface.

• Journal of the Korean Society of Costume
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• v.38
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• pp.159-178
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• 1998

Genres of the modern arts are expanding the overlapping area between the arts ; ceramics and weaving considered as crafts are devel-oped to the ceramic art and the fiber art, re-spectively. This trend has been also applied to the clothing part, which produced several new terms such as‘art to wear’,‘unwearable art’,‘clothing sculpture’and so on. As following this tendency, the unwearable art is dwelling on the boundary of painting, fiber art and scul-pture, and the clothing sculpture comes from the combination of fiber art and sculpture. While Issey Miyake's dress made of bamboo and Foltuny's pleats dress associated with Greek stone-column introduce the sculpture to the functional fashion design, the works of clothing sculpture become the arts by applying the sculpture to the non-functional unwearable art. Although the clothing sculpture is an interesting subject to be studied continuously for its effect on the contemporary clothing part, it is valuable enough as an unwearable art and sculpture respresenting the artist's concept under the circumstance that the boundary between arts and design is no longer clear, i.e., the clothing and the sculpture come across their regions each other. Furthermore, the clothing sculpture has its own value as a metapor exposing idea, feeling and spirit of the artist in the genre of the unwearable art. With a view point of the abstract clothing concept, the clothing sculpture has been taking the role expanding the clothing to the world of fine art.

• Korean Journal of Human Ecology
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• v.24 no.5
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• pp.687-700
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• 2015

Lines of non-extension (LoNEs) on torso surface during arm abduction were investigated to provide appropriate location for inserting less-extensible yarns which can be used as seams for design and or clothing pressure variation. As experimental methods, reference points about 3 cm apart were marked on the skin and scanned at 30, $90^{\circ}$ and $135^{\circ}$ arm abduction. Skin deformation was measured by connecting reference points in horizontal, vertical and various angles of diagonal directions. Observation of skin deformation was made within the separated sections of the torso as well as integrated ones to cover the various occasions of design application. LoNEs of front and back torso were provided as mapping lines. Actual compression wear of three types was constructed with different pattern reduction rate at each separated section using LoNEs as boundary cutting lines. Clothing pressure and subjective evaluations of those three compression wear were evaluated by six subjects. LoNEs found in this study were useful as seam lines to differentiate clothing pressure at each part of the body, providing positive wear sensation. It is also expected that LoNEs can be paths for less strechable conductive yarns of IT-integrated upper garments.

• Tribology and Lubricants
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• v.24 no.3
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• pp.122-128
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• 2008

To reduce the friction losses and the wear amounts in the piston assembly two methods were proposed. One is the modification of surface profile of the skirt part. The surface coating is another method to protect the sliding surfaces. To modify the profile of the skirt surfaces the surfaces were ground to have three different shapes of profiles. Also, several coatings, such as graphite, TiN, and $MoS_2$, and DLC, were used to protect the surfaces of the piston skirts. The specimens of the skirt and the cylinder bores were tested with the reciprocating wear tester. SAE 5W40 engine oil was used in boundary lubrication regime. Among several coatings the graphite and DLC coatings were very effective to reduce the friction forces. Especially, DLC film represented much better tribological performances than the others. The friction coefficient of the graphite coating was the lowest, but the graphite coating was not effective to protect the surfaces.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.5
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• pp.856-877
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• 2020

This study examines how class differences are expressed through costumes based on the costumes of characters in Bong Joon-Ho's film . Based on Video on Demand (VOD), the main situations in which characters' costumes change in the play were captured and used as analysis data. Colors, textures, and color symbol were analyzed to find the formative properties shown in the characters' costumes. The results are as follows. The home wear of Kim's family were unsuitable for the top and bottom, faded clothes, and the vague boundary between outdoor and indoor clothes appeared. In comparison, Park's family's home wear was featured a modern and elegant design, a clear distinction that suited purpose and situation. Analysis of street wear showed that the Kim's family had a big difference before and after getting a job, and Park's family wore different costumes for the purpose of going out. Social class expressed in the film costumes were shown to have the characteristics of intrinsic class invariance, temporary class changes, differences in class expression by age, and differences in costume choice by class.

• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.685-692
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• 2001

This paper reports on the mixed lubrication characteristics between the cam and the tappet contact surface of direct acting type valve train systems. First, the dynamic characteristics are solved by using the lumped mass method to determine the load conditions at the contact point. Then, the minimum oil film thickness is calculated with consideration of elastohydrodynamic line contact theory and the friction force is obtained by using the mixed lubrication model which separates the hydrodynamic and the boundary friction. Finally, the average surface temperatures are calculated by using the flash temperature theory. The results show that, there are some peaks in the friction force due to the asperity contact friction, and flash temperature at the position of minimum oil film thickness. It is thought that there is a relationship between the surface temperature and cam surface wear, and therefore, the analysis on the worn cam profile has been performed.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.73-74
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• 2008

This paper analyses current densities induced inside a worker using AC arc welder when he wear a protective with double shielding cloth. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm] far from a power cable of AC arc welder. As results of study, we fined aa protective cloth, which has high permeability in inner layer and high conductivity in outer layer, can give a higher shielding efficiency.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.145-151
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• 1997

PAG(Polyalkylene Glycol) and esters are tested with HFC-134a as a refrigeration oil. This investigation enhances the testing method by taking the compressor's environment into account. A testing environment charged with refrigerant gas more closely simulates the conditions of a compressor. The friction coetTicient of the PAG/HFC-134a system is similar to that of the mineral oil/CFC-12 system at operating conditions. Ester oils are preferable at the start & stop condition in the lubricity aspect. PAG shows good lubricity in conditions of extreme contact pressure. Consequently, this test provides reliable results on compressor lubricity of refrigeration oils with HFC-134a. It suggests a methodological way for the proper selection of refrigeration oils that may improve the durability and performance of a compressor.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.4
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• pp.101-116
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• 2016

"Athleisure" indicates a new fashion style which takes advantage of the merits of both sportswear and outdoor clothing. This fashion style produces clothing we can wear very conveniently regardless of time and place. This paper, first, surveyed the concept of athleisure and the socio-cultural background of its appearance in modern fashion, and then, analyzed the growing processes and tendencies of athleisure in various fields of fashion. The three typical characteristics of athleisure can be summarized as Non-boudary, Functionality, and Sensualirty. It is hoped that this study has provided some theoretical evidences for the athleisure which is expanding broadly but vaguely as megatrends.