• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.22-29
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• 2001

Plasma-sprayed coatings were prepared using by spray-dried Cr$_2$O$_3$ powder with and without MoO$_3$ addition. A reciprocal type tribe-tester was employed to examine friction and wear behavior of the specimens at room temperature. The worn surfaces of plasma spray coated specimens were observed by SEM. The results showed that friction coefficient of the MoO$_3$-added coatings were lower than those without MoO3 addition. However pure Cr$_2$O$_3$ coating showed the lowest wear loss at the self-mated test. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with MoO$_3$ addition.

• International Journal of Railway
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• v.3 no.1
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• pp.19-27
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• 2010

In the present study, the electrical sliding wear and corrosion resistance of pure copper (Cu) and six age-hardened copper alloys (CuCr, CuZr, CuCrZr, CuNiSiCr, CuBe and CuBeNi) were investigated by a pin-on-disc tribometer and electrochemical measurement. Various copper-based alloys in the form of cylindrical pin were forced to slide against a counterface stainless steel disc in air under unlubricated condition at a sliding velocity of 31 km/h under normal load up to 20 N with and without electric current. The worn surface of and wear debris from the specimens were studied by scanning electron microscopy. Both mechanical wear and electrical arc erosion were the wear mechanisms for the alloys worn at 50 A. Owing to its good electrical conductivity, high wear and corrosion resistance, CuCrZr is a promising candidate as the overhead catenary material for electric traction systems.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.3
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• pp.105-113
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• 1991

The practicability of Ion-Sputter machining renders it possible to make diamond stylus for surface roughness measurement with micro stylus tip radius less than 2${\mu}mR$, and to measure surface roughness of fine-machined surface. In this study, we researched the wear or Ion-Sputtered stylus with 0.1${\mu}mR$ and 0.5${\mu}mR$ for micro-figure measurement and polished stylus with 0.5${\mu}mR$ according to measurement distance. As a result, we know that the case of Ion-Sputtered stylus is worn down easilier the case of polished stylus. And we know that in the evaluation of stylus wear, it is more useful method that examine the wear by measuring the variation of stylus tip radius than by evaluating the variation of Ra values.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.128-134
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• 1993

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions and lubrication. The tests were performed to find the effects of rolling materials under the same lubrication conditions. The obtained results are as follfws; 1) The decrease in surface roughness of work roll is more rapid in that case of continuously cast A1-killed steel strip than ingot cast steel strip. In rolling of continuously cast A1-killed steel strip, worn powder rich in A1$\_$2/O$\_$3/sticks to the work roll surface, and so it makes the mirror surface of work roll accelerate. 2) Amount of work roll wear is small in rolling of continuously cast A1-killed strip. 3) In rolling of continously cast A1-killed steel strip, it is necessary to put up the intial surface roughness of work roll in order to prevent work roll slip.

• Journal of the Korean Society of Clothing and Textiles
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• v.9 no.2
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• pp.45-55
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• 1985

The main purpose of this study is to investigate the suitability of Boesun (the Korean Socks) to the foot. In order to find the problem of Boesun, I made up the questionnaire. The suitabltity of Boesun to the foot was experimented by 'the replica method', 'the fuse method' and 'the deform painting method'. The pressure of Boesun to the foot was measured by utilizing a human sensitivity as a sensor. The results were as follows. 1. In the questionnaire, the fore part of Boesum was uncomfortable by the pressure. 2. The surface area of Boesun was generally smaller than the surface area of the foot, but the ratio of two surface area related closely to the individual. 3. At the cross-sections from No. 1 to No. 10, the breadth of the worn Boesun was smaller than the breadth of the foot. Because of the smaller breadth of the worn Boesun, the foot was get the pressure at the fore part of Boesun. This result accorded with the result of the questionnaire. 4. The location of the deformation by 'deform painting method' was almost the fore part of Boesun. 5. The pressure of Kwon's Boesun was 2.57$\~$2.99kg, the pressure of Kim's Boesun was 1.31$\~$1.74 kg and the pressure of Lee's Boesun was 3.42$\~$3.88kg. Compared with the distribution chart of the pressure, Kwon's Boesun was involved the back part of 'slightly pressured' and the fore part of 'pressured', Kim's Boesun was involved the fore part of 'slightly pressured' and Lee's Boesun was involved the middle part of 'pressured'.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.271-278
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• 2006

We used polymers of alternating cationic and anionic nature to build up shells on fiber surfaces, strengthen the worn-out fibers and improve paper properties made from such fibers. OCC and ONP pulps were either dipped or salted out in the cationic polyallylamine, polyacrylamide and starch solutions. After centrifugal drying, these were followed by treatments in anionic polyacrylic acid, poly-acrylamide, and starch solutions, respectively. The shell-enhanced fibers were formed into handsheets and their physical properties evaluated. The results show that building multiple shells on worn-out fiber surfaces can strengthen the fibers and paper. The simpler and more practical impregnation-centrifuging treatment provided the desired effects, whereas salting out the polymers produced somewhat superior fibers. The latter process, were impractical, however. The first pair of polymeric shells imparted marked strength improvement, whereas later layers had diminishing efficacies. Overall, the methods can improve fiber quality, attaining paper strength requirements without resorting to expensive measures. Alternate cationic polymer and filler powders were also deposited on fiber surface based on the micriparticle system in an anticipation of stiffness gains. Platy minerals, such as montmorillonite, bentonite, sericite, clay and talc were added following cationic PAM. After dewatering of polymer-pigment shelled fiber of one to 3 pairs of layers, handsheets either calendered or uncalendered were evaluated. The results indicate that regardless of calendaring, stiffness of the handsheets did not improve appreciably while certain other strength properties showed gains. We also attempted the novel starch gel filler addition method wherein tapioca starch and filers (PCC, sericite or clay) were mixed at high solids content of 50% and cooked until gelatinized. The filled handsheets were dried under various conditions and then tested for their properties. Improvements in strengths of modified filled paper were observed.

• The Journal of Korean Academy of Prosthodontics
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• v.19 no.1
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• pp.47-54
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• 1981

Dental porcelains are widely used for restorative material because of its excellent esthetic property. But according to contact with natural teeth or metal in oral cavity, the porcelain may be worn and may effect on masticatory physiology and prosthetic function. The purpose of this experiment was to study on wear of porcelain surface which treated in different method. Using the abrasion device which was designed and constructed by myself, the different porcelain surface were abraded by gold alloy, nickel-chrome alloy and natural teeth in order to compare roughness. Results were as follows. 1. The group of porcelain abraded by gold alloy showed less surface roughness change (t=2.92, p<0.05), and the group of porcelain abraded by natural teeth had high surface roughness. change (t=6.84, p<0.05). 2. According to the method of surface treatment, the surface roughness were very significant (F=9.12, p<0.05). 3. After abrading, the porcelain surface roughness change was very significant (F=54.49, p<0.05). 4. There was no significant between surface treatment method and the kind of abrading materials. (F=1.01, p>0..05). 5. The group of natural glazing had the most smooth surface ($2.1{\pm}1.13{\mu}m$).

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.721-725
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• 1998

In this study solid-phase sintered silicon caribide samples composed of SiC powder having boron and car-bon black as additives were prepared by pressureless sintering at $1950^{\circ}C$. The bending strength the frac-ture toughness and the specific werar rate of the samples were examined and the micro structures of the broken and the worn surface were observed by SEM to understand the relationship between the tri-bological charcteristics and the micro structure. Additionally the relationship between the micro struc-tures and the tribological characteristics of the samples for the frictional opponents SiC and $Al_{2}O_{3}$ pins were investigated Conclusions are as follows ; 1. The specific were rate of the samples for the SiC pin was larger than that for the $Al_{2}O_{3}$ pin. HOwever the specific wear rate for the $Al_{2}O_{3}$ pin was increased about 6,45 times as that for the SiC pin under the load increasing. 2. The specific wear rate of the SiC pin was larger than that of the $Al_{2}O_{3}$ pin. owever the specific wear rate of the $Al_{2}O_{3}$ pin was increased about 4 times as that of the SiC pin under the load increasing 3. The micro stucture of the worn surface showed a flat face without cracks in the case that the frictional opponents has the low friction coefficient but in the case of without cracks in the case that the frictional opponents has the low friction coefficient but in the case of the high friction coefficient the micro structure of the worn surface showed an uneven face having spread-ed cracks. 4. The tribological characteristics of thesolid-phase sintered SiC samples was similar to that of li-quid-phase sintered ones when the pin having the high friction coefficient was used.

• Korean Journal of Human Ecology
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• v.19 no.6
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• pp.1045-1052
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• 2010

Effects of the ease of pattern on the thermal conditions of clothing were investigated through the measurement of clothing surface temperatures using infrared thermography. Four vests with different pattern ease were worn by five male subjects. Surface temperature distribution on the clothing were then examined using a thermogram to view thermo-regulating characteristics affected by the ease of pattern. Representative surface temperatures were calculated based on the percentage of the surface area within a certain temperature range and the midpoint value of the corresponding area. Representative surface temperatures matches well to the thermal insulation value measured by thermal manikin. Results indicated that representative surface temperature could be a useful quantitative value if some simple calculations were to be used alongside accurate image processing.