• Tribology and Lubricants
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• v.16 no.2
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• pp.121-125
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• 2000

Silicon nitride ceramic has been verified as an excellent rolling bearing material because of its high strength and outstanding rolling fatigue life properties. However under some corrosive circumstances it showed drawbacks such as hardness reduction and severe wear caused by corrosion. In this work, the variations of the rolling wear and hardness of three kinds of ceramics were studied for the specimen aged 15 days in alkali water (90 $\pm$ 2$\^{C}$,25 wt% NaOH ). All of the specimens, ① Si$_3$N$_4$, ② 3Y-TZP and ③ 3Y-TZP alloyed with 5 wt% CeO$_2$, were sintered and post-HIPed, and then polished up to 0.02 $\mu$mRa of surface roughness. Rolling wear tests were conducted by MJ type rolling fatigue life tester under the initial theoretical maximum contact stress of 3.16 GPa and the spindle speed of 1,000 rpm. Spindle oil was used as a lubricant. The specimens were not worn before aging. For the specimen aged in alkali water, Si$_3$N$_4$ and 3Y-TZP were worn by rolling wear tests, and hardness was decreased. While aging the specimens, the phase was transformed from tetragonal to monoclinic in 3Y-TZP and the microstructure change occurred in Si$_2$N$_4$. 3Y-TZP specimens alloyed with 5 wt% CeO$_2$ were not worn after aging and no phase transformation occurred while aging.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.154-159
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• 1999

Silicon nitride ceramic has been verified as an excellent rolling bearing material because of its high strength and outstanding rolling fatigue life properties. However under some corrosive circumstances it showed drawbacks such as hardness reduction and severe wear caused by corrosion. In this work, the variations of the rolling wear and hardness of three kinds of ceramics were studied for the specimen aged 15 days in alkali water (90$\pm$2$^{\circ}C$, 25 wt% NaOH). All of the specimens, \circled1Si$_3$N$_4$, \circled23Y-TZP and \circled33Y-TZP alloyed with 5 wt% CeO$_2$, were sintered and post-Hipped, and then polished up to 0.02 ${\mu}{\textrm}{m}$Ra of surface roughness. Rolling wear tests were conducted by MJ type rolling fatigue life tester under the initial theoretical maximum contact stress or 3.76 Gra and the spindle speed of 1,000 rpm. Spindle oil was used as a lubricant. The specimens were not worn before aging. For the specimen aged in alkali water, Si$_3$N$_4$and 3Y-TZP were worn by rolling wear tests, and hardness was decreased. While aging the specimens, the phase was transformed from tetragonal to monoclinic in 3Y-TZP and the microstructure change occurred in Si$_3$N$_4$. 3Y-TZP alloyed with 5 wt% CeO$_2$specimens were not worn after aging and no phase transformation occurred while aging.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.200-207
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• 1999

A new method for the calculation of a wear amount was suggested. The amount of wear was calculated by the comparison of worn out profile with an estimated original profile. An original profile of wear track was estimated by comparing with outside of wear track. An estimated surface profile was well fitted to the original profile assumed unknown.

• The Journal of the Korean dental association
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• v.54 no.6
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• pp.438-446
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• 2016

Severe tooth wear may cause the pathologic change of the TMJ and masticatory muscles, unesthetic facial appearance, pathogenic pulp and occlusal disharmony. Treating patients with severely worn dentition often requires full mouth rehabilitation with increasing vertical dimension. Proper diagnosis and treatment planning are important for esthetic and functional definitive restorations and the long term stability of the neuromuscular system and the TMJ. In this case, 66 year-old female presented with generalized worn dentition. Based on assessment, pathologic destruction of teeth structure on entire dentition was caused by masticatory force and diet habit without loss of vertical dimension. Subsequently, 3 mm increase of vertical dimension that based on incisor for tooth restoration and esthetic improvement was determined. After 8 weeks stabilization period with temporary fixed prostheses, definitive prostheses were fabricated. After 6 months follow up period, satisfactory outcomes were attained both functional and esthetic aspects through this procedure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.975-979
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• 2002

This paper studies the indirect parameters when the new and worn end mill working in the machining center. The parameter output methods are cutting force, current values and AE signals. In the result, when the worn end mill operating, cutting forces increase the 14.71〔N〕, current values increase the 2.917〔A〕 and 1.168〔A〕 according to the spindle mote. and feed motor, and AE signals increase the 0.588$\times$10$^{-5}$ 〔A〕. We can use these parameters in the detection of end mill wear.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.69-77
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• 2001

Wear and Friction characteristics of plasma-sprayed Cr$_2$O$_3$ coating and Cr$_2$O$_3$ coating included SiO$_2$ and TiO$_2$ against SiC ball have been investigated under different loads. Worn surfaces were observed by SEM and worn surfaces were analyzed by EDS. The Friction coefficient and the Wear resistance of Cr$_2$O$_3$-5SiO$_2$-3TiO$_2$coating was less than that of Cr$_2$O$_3$ coating. The main mechanisms were plastic deformation and brittle fracture. The film on surface were made by plastic deformation and compacted wear debris. This film protect wear of coating

• Korean Journal of Materials Research
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• v.15 no.1
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• pp.61-65
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• 2005

The titanium $diboride(TiB_2)$ has high strength(750MPa), high melting point $(3225^{\circ}C)\;and\;10\%$ IACS electrical conductivity. On this account, the dispersion hardening $Cu-TiB_2$ composites(MMCs) are a promising candidate for applications as electrical contact materials. MMCs for electrical contact materials can reduce material cost and resource consumption caused by wear, due to its good mechanical and electrical property. In this study, we attempt to prepare MMCs with various volume fraction and particle size of $TiB_2$ by means of hot extruded and cold drawn process. Dry sliding wear tests were performed on a pin-on-disk type wear tester, sliding against SM45C under the different applied loads. After wear testing, the microstructures of the worn surfaces were observed by SEM and the microhardnesses of the subsurface zone were measured.

• Journal of the Korean Society of Costume
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• v.34
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• pp.169-182
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• 1997

Focusing on khotan located in the southern Silk Route which was one of the most important kingdoms in the Tarim Basin this study attempts to examine the changes of costume in Khotan by compar-ing the costumes in the painted panel showing the story of silk princess with the excavated costumes from ancient tombs. Furthermore this study attempts to inves-tigate the impacts of cultural exchange be-tween China and its western neighboring country Eastern and Western Turkestan on costume. Excavated costumes from the Shanpula ancient tomb in the region of Khotan and from ancient Niya in the esat-ern border of Khotan and discoveries from Rawak and Dandan-oilik near by Yotkan the ancient capital of Khotan are exam-ined. Basic Khotan's costume was the two piece style of tops and trousers. Over the basic costume wearing a top wear with half sleeves was popular. Skirt was worn by women. Even though there were many kinds tops were classified into the two types kaftan and tunic. Thouth Khotan maintained a association with China for a long time the style of Khotan costume had imbued to China. Top wear with half sleeves was worn frequently in Khotan. Also in China top wear with half sleeves was worn as over-wear which was called ban-xiu ban-bi bei-zi Costume style of China is covering the body profoundly and wrapping front edge toward the right. The types of chi-nese top wear with half sleeves for exam-ple round-neck·confronting front edge crossing-neck·confronting front edge tu-nic type discord with the traditional chi-nese costume style There were many cas-es that half sleeved top wear was worn as over wear in T'ang dynasty. The phenom-enon was due to the prevalence of 'ho' (foreign) and half sleeved top wear was introduced by the countries to the west of China Khotan. A round neck garment was a general type for the men of cuntries to the westof China. Also Chinese wore round neck garment since South and North Dynasty The type of Chinese round neck garment was not tunic but kaftan. From costume relics and ancient paintings the type of Khotan's round neck garment was tunic which was recorded on the Chinese histori-cal documents as " guan-tou-shan" that is tunic the type of persian costume, Even thgough the painted panel showing the sto-ry of silk princess was made in the it me when Turks was a dominion on Central Asia Khotan's costume style was not changed toward Turk's costume style and remained tunic style.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.66-71
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• 2006

A geometric contact conditions of wheel/rail affect the dynamic behavior of rolling stock. Mechanical force acted on the wheel/rail causes excessive wear and increase the maintenance cost. In this study, we have studied the dynamic behavior of the urban railway vehicle with new and worn wheel by VAMPIRE program. And we have tested the accelerations of wheelset on the conventional line. The results of simulation are compared with the measuring data of field test. It shows that the acceleration of worn wheel is greater than the acceleration of new wheel in the straight track line but on the contrary, the acceleration of new wheel is greater than the acceleration of worn wheel in curved track. That results explain that the new wheel is worn out greater than the worn wheel in curved track line and need to be maintained more seriously when running in curved track line.

• Fashion & Textile Research Journal
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• v.18 no.4
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• pp.399-411
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• 2016

This research reviewed the developmental process of domestic outdoor wear and later analyzed the images given out by men's outdoor wear. The research results are as follows. First, military supplies left by American soldiers were dyed or reformed and then worn, and daily wear were mainly worn in the 1960s. Wears made from light and waterproof materials were worn and equipments were used in the 1970s. High functioning materials which allowed simultaneous breathability, waterproof and thermal insulation functions were used for wears in the 1980s. For the jacket especially, functionality was enhanced sith zippers, snaps and velcro to prevent cold air penetration in the 1990s. Florescent piping decorations and logo decorations, and prints and colors which reflected the trend, were used to emphasize fashionity and decorativeness in the 2000s. Second, Sophisticated image emphasized urban feeling with toned-down windbreaker jackets without much detail, with down jacket and pants. Casual image expressed a relaxed feeling with windbreaker jacket, shirts, jumper, vest and pants made of cotton, mesh knit and denim. Active image emphasized functionality by brightly colored windbreaker jackets, down jacket and pants. Ethnic image expressed an exotic mood with windbreaker jackets with stylized prints, with jumper, down jacket and pants. Military image showed a strong masculine feeling with jackets adorned with epaulettes, khaki colors and camouflage prints, with jumper, T-shirts, vest, shorts and pants. Avantgarde image exuded an experimental and unique feeling with jackets made of various colors and materials, such as cotton, jersey and glossy materials, with down jacket and jersey pants.