• Textile Coloration and Finishing
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• v.19 no.2
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• pp.24-31
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• 2007

This paper addresses factors of line image quality on grain leather printed via inkjet printer. Lines were printed onto coated leather media, and line width, edge blurriness, and edge raggedness were evaluated for line image quality. Various factors influenced to wetting and capillary wicking were studied and found out that wicking through capillary between fibers causes significant feathering on leather surface similar with pulp capillary in copy Paper. Polyurethane and acrylic resin coating resulted good image qualify by reducing capillary wicking. The mixture of polyurethane and acrylic resin applied on grain leather satisfied with both image quality and surface hand. $AllWrite^{TM}$ ink brought best results of image quality, comparing with $VeraPrint^{TM}$ ink and $JetWrite^{TM}$ ink.

• Journal of the Korean institute of surface engineering
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• v.35 no.4
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• pp.218-231
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• 2002

As the environmental regulation worldwide emerges, most notably in Europe and Japan, the elimination of Pb usage in electronic assemblies has been an important issue for microelectronics assembly due to the inherent toxicity of Pb. This has provided an impetus towards the development of Pb-free solders. A major factor affecting alloy selection is the melting point, since this will have a major impact on the other polymeric materials used in microelectronic assembly and encapsulation. Other important manufacturing issues are cost, availability, and wetting characteristics. Reliability related properties include mechanical strength, fatigue resistance, coefficient of thermal expansion and reactivity with substrate. In this article, Pb-free solder alloys have been proposed so far have been reviewed and are summarized.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.1042-1048
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• 2001

When a liquid is supplied through a nozzle onto a relatively non-wetting inclined solid surface, a narrow rivulet forms. This work provides novel physical insights into the following phenomena in the rivulet flow that have not been well understood to date. Firstly, the fundamental mechanism behind the transition of a linear rivulet to a droplet flow is investigated. The experiments show that the droplet flow emerges due to the necking of a liquid thread near the nozzle. Based on the observation, it is argued that when the axial velocity of a liquid is slower than the retraction velocity of its thread, the bifurcation of the liquid thread occurs, and this argument is experimentally verified. Secondly, a discussion on the curled motion of a meandering rivulet is given. This study proposes the contact angle hysteresis as a primary origin of the centripetal force that enables the rivulet\`s curved motion. A simple scaling analysis based on this assumption predicts a radius of curvature which agrees with the experimental observation.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.904-909
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• 2008

Most of current slope safety analysis consider only the effect of the rise of underground water level. However, because the infiltration of surface water into the ground is believed to have signification effect on slope stability, the present study performed slope safety analysis in case of the rise of underground water level, infiltration of surface water, and both resulting from rainfall, and examined their effect.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.47-51
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• 2011

Main issues in the automotive industry are the reduction of vehicle body weight for energy savings and improvement of crashworthiness for passenger safety. In order to address both these issues, there has recently been increasing application of galvannealed advance high strength steel (GA AHSS) sheets for automobiles. However, GA AHSS sheets have some surface defects such as coating bare spots due to the addition of solid-solution strengthening elements, which result in the deterioration of the galvannealing reaction. In this study, the effects of galvannealed manufacturing conditions on surface and mechanical properties, resistance spot weldability on a laboratory scale, and GA 980 MPa steel sheets produced by commercial continuous galvannealing line (CGL) were investigated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.192-192
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• 2011

본 연구에서는 LED lead frame을 위한 Sn-3.5Ag 솔더의 젖음 특성과 반사율에 관하여 조사하였다. 금속기판과 액체금속간의 젖음성은 wetting balance tester를 이용하여 평가하였으며, 최대인출력, 최대인출시간 등을 측정하고 표면장력을 계산하였다. Sn-3.5Ag 솔더를 $250{\sim}290^{\circ}C$의 온도에서 젖음성을 측정하였는데 온도가 증가함에 따라 젖음성이 향상되는 것을 확인할 수 있었다. 또한 솔더가 도금된 Cu-coupon의 반사율을 측정하였는데 $270^{\circ}C$에서 가장 높은 반사율을 나타냈다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.187-187
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• 2011

지르코니아 ($ZrO_2$) 표면에 금속 (Au)으로 표면 코팅한 후 Ti-6Al-4V와 진공 브레이징 접합을 행하였다. 표면에 코팅한 Au 층의 영향을 비교 분석하기 위하여 Au를 코팅하지 않은 지르코니아도 모재로 사용하였다. 접합소재로는 Ag-Cu-Ti계 active filler를 사용하였다. $ZrO_2$/Ti-6Al-4V 브레이징 결과, active filler는 양측 모재 표면에 wetting 되었으며, Ti-6Al-4V 내부로 filler 확산으로 인하여 두 모재의 direct joint가 관찰되었다. 접합 계면 사이에 접합부 결함은 관찰되지 않았다.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.79-90
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• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.444-449
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• 2010

In this study, the petroleum sulfonate(PS) was synthesized from pyolyzed fuel oil by sulfonation reaction with sulfuric acid. The PS synthesized had surfactant behaviors relating to the interfacial properties such as surface tension, surface adsorption, and wetting, etc. These interfacial properties were affected by the sulfonation ratio in the synthesis. As the sulfonation ratio increased, the surface tension of the PS aqueous solution decreased. However, when the ratio was too high, the surface tension was increased due to the extremely higher value of hydrophilicity of PS. At the optimum sulfonation ratio, the PS had a good wettability on the cement particles and a good fluidity of the cement mortar with a high adsorption.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.38-44
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• 2020

Surface texturing of micro-dimples has been used in many manufacturing industries to reduce friction between two sliding contacted surfaces. Surface texturing decreases the frictional force owing to minimizing of the sliding contact area. In this paper, micro-dimples have been fabricated on an Al6061-T6 surface using a two-frequency elliptical vibration texturing (TFEVT) method. A high-frequency of 18 kHz and low-frequency of 250 Hz were applied to an elliptically-vibrated tool holder. The Stribeck curve was plotted to analyze the friction coefficient trends. Furthermore, the representative wetting index, such as the water contact angle (WCA), was measured by considering the friction coefficient. WCA is associated with micro-dimple density and associated parameters. Consequently, the dimpled surfaces with a low friction coefficient exhibited a relatively high WCA in the feed direction. According to the Stribeck curve, the dimpled surfaces demonstrate superior friction performance for mixed-film lubrication compared to the non-textured surface.