• 한국정밀공학회지
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• 제26권5호
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• pp.57-63
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• 2009

Interface friction in blanking dies, cold forging and extrusion of aluminum alloys is a major cause of inefficient process. This paper describes an investigation of femtosecond laser texturing for reduction of interface friction on sliding surfaces in forming process. Femtosecond direct writing technology was used to fabricate a laser micro-machined die and to create microgroove patterns with varying size and density on metal forming dies. A systematic approach to find the optimum parameters and computer simulation comparison of friction coefficients are provided to study the relation of friction coefficients and die profiles. In metal forming tests, the effectiveness of various laser-machined patterns for enhancing interface lubrication is determined.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1145-1150
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• 2005

The aim of this paper is to investigate the effect of surface texturing on metal surface and to understand the potential of friction reduction through micro-scale dimple to fabricate by photolithography on pin-on-disk test using flat-on-flat contact geometry. It was verify that the friction property with respect to the same pitch has been influence on the size of dimple under lubricated sliding contact. Also, we can recognize from Stribeck curve that the friction property has a connection with the size of dimple. It can explain a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. The friction property has been an effect on the size of surface texture on reduction friction, not only because the density of dimple, but also because the ratio of diameter/pitch. This ratio of approximately 0.5 is recommend under the tested friction condition. It suggested that the ratio of d/p is an important parameter for surface texture design.

• Tribology and Lubricants
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• 제26권1호
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• pp.1-6
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• 2010

In the last decade, laser surface texturing (LST) has emerged as a viable option of surface engineering. Many problems related with mechanical components such as thrust bearings, mechanical face seals and piston rings, etc, LST result in significant improvement in load capacity, wear resistance and reduction in friction force. It is mainly experimentally reported the micro-dimpled bearing surfaces can reduce friction force, however, precise theoretical results are not presented until now. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the lubrication characteristics of a parallel thrust bearing having 3-dimensional micro-dimple. The results show that the pressure, velocity and density distributions are highly affected by the location and number of dimple. The numerical method and results can be use in design of optimum dimple characteristics, and further researches are required.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.127.2-127.2
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• 2011

본 연구에서는 RF Magnetron Sputtering System을 이용하여 ZnO계 투명전도막 증착시 Vaporization된 MeOH를 유입함으로써 박막증착과 동시에 표면의 Roughness를 제어하여 이에따른 전기적 특성 및 광학적 특성의 개선에 대하여 연구하였다. 실험방법으로 기존의 RF Magnetron Sputtering System에 Vaporization이 가능한 Ultrasonic을 이용하여 MeOH를 Vaporized시켜 MFC Controll을 통해 챔버에 유입하여 ZnO계 투명전도막의 박막증착과 동시에 표면 Texturing을 하였다. ZnO계 투명전도막의 박막증착시 Vaporized MeOH의 유입에 따른 광학적 특성변화를 UV-visible-nIR spectrometry로 조사하였으며, 전기적 특성 변화를 4-Point-Probe로 조사하였으며, 표면적 특성 변화를 Atomic Force Microscope(AFM), Scanning Electron Microscopy(SEM)를 조사하였으며, 박막의 결정성장특성 변화를 X-ray Diffraction(XRD)으로 조사하였으며, Vaporized MeOH 유입에 따른 박막의 성분분석을 Secondary Ion Mass Spectrometry (SIMS)로 조사함으로써 최적의 조건 및 공정을 확립하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.17-24
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• 2004

Surrface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

• Fibers and Polymers
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• 제5권1호
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• pp.19-24
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• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• 한국세라믹학회지
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• 제30권2호
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• pp.164-168
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• 1993

Grinding of 3mol% Y-TZP enhanced the texturing of t-ZrO2, which is represented by the increased I(002)t/I(200)t peak intensity ratio, and an asymetric broadening of (111)t peak. The degree of texturing and asymetric broadening depended on a seversity of grinding. The asymetric (111)t peak broadening was resulted by the formation of r-ZrO2. When aged at 25$0^{\circ}C$ for 120h, r-ZrO2 transformed to t-ZrO2 due to the relief of stressed surface area and the amount of tlongrightarrowm transformation inversely varied with the I(002)t/I(200)t. The inverse dependence was interpreted by that the degree of texturing determines the magnitude of residual surface stress and the lattice relaxation of t-ZrO2, which causes the low temperature degradation, is retarded as the residual stress becomes greater.

• 한국기계가공학회지
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• 제12권1호
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• pp.28-34
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• 2013

For the senses of beauty and texture, internal components of small passenger cars are manufactured by texturing plastic with drawplate but those of deluxe passenger cars are manufactured by bonding pre-embossed skin to the surface of drawplate. As the pre-embossed skin is bonded at high temperature and pressure, the pattern of skin is distorted. The corner part is hardened and its dimension tolerance is changed by resulting in the increase with its defective rate. This study provides the method to design and manufacture the door trim track by vacuuming the non-patterned skin to upper-side drawplate which forms the pattern of descending skin. It is pressed to the plastic product with hot-press method and the damage of bossed-pattern is prevented. Valuation in this study has been done by analyzing, designing and experimenting method.

• 감성과학
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• 제10권3호
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• pp.367-372
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• 2007

본 연구에서는 유체시스템을 이용한 나일론 필라멘트의 실크감성화 기술을 연구하였다. 이를 위해서 타스란 텍스쳐링 ATY 기계를 개조하였으며, 4가지의 40d/12f 나일론 소재가 개조된 ATY기계에서 기능성 약제를 이용하여 만들어졌다. 이들 소재사를 사용하여 4가지 직물이 제조되어 염색 가공 공정을 진행시켰다. 그리고 이들 직물시료의 수분율, UV차단성, 직물태등과 같은 여러 가지 물성을 측정하였으며, 이들 물성을 ATY텍스쳐링 조건과 기능제 처리조건과 비교 분석하였다.

• Tribology and Lubricants
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• 제25권3호
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• pp.141-149
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• 2009

The effect of micro-cavities fabricated using laser surface texturing (LST) technique on polyoxymethylene (POM) surface was studied in terms of heat affected zone (HAZ), cavity geometry, surface roughness, deformation of cavity along with sliding cycles, and tribological characteristics. Cavity process parameters were lamp current, process time, and the stream of air used to minimize the flow of molten polymer into cavity. Especially, the deformation of cavity geometry was extensively studied to provide deep insight into morphological analysis of the cavities. Also, this paper presents the behavior of friction and wear of POM specimens as a function of sliding cycles.