• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.91-92
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• 2012

• 한국생산제조학회지
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• 제22권1호
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• pp.15-21
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• 2013

In this paper, a high-speed imaging and an image processing technique have been applied to detect the position of a meniscus as a function of time in the micro capillary flows. Two fluids with low and high viscosities, ethylene glycol and glycerin, were dropped into the entrance well of a circular capillary tube. The filling times of the meniscus in both cases of ethylene glycol and glycerin were compared with the theoretical models - Washburn model and its modified model based on Newman's dynamic contact angle equation. To evaluate the model coefficients of Newman's dynamic contact angle, time-varying contact angles under the capillary flows were measured using an image processing technique. By considering the dynamic contact angle, the estimated filling time from the modified Washburn model agrees well with the experimental data. Especially, for the lower-viscosity fluid, the consideration of dynamic contact angle is more significant than for the higher-viscosity fluid.

• 대한기계학회논문집A
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• 제38권8호
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• pp.823-829
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• 2014

본 연구에서는 계면활성제를 첨가한 사각 PDMS(polydimethylsiloxane) 마이크로 채널에서의 모세관 흐름에 의한 충전 길이를 예측하기 위한 모델들을 제안하였다. 일반적으로 PDMS 의 소수성 특성 때문에 모세관 힘만을 이용한 PDMS 마이크로 채널에서의 물의 이동에는 어려움이 따르게 된다. 따라서 본 연구에서는 계면활성제를 첨가하여 친수성을 가지는 PDMS 표면을 제작하고, 이 표면에서의 물의 접촉각 변화 측정 및 단순 모델을 수립하였다. 또한 친수성 PDMS 마이크로 채널에서의 모세관 힘에 따른 충전 길이를 예측하기 위해서 Washburn 방정식을 바탕으로 한 단순 모델을 수립하였다. 그 결과 유체의 충전 길이는 접촉각의 초기변화속도의 영향을 받는 것을 확인할 수 있었다. 이를 바탕으로 대표적인 세가지 경우에 대한 모델을 제안하였으며, 이들은 MIMIC(MIcroMolding In Capillaries)과 같은 마이크로 유체 기반의 생산공정의 설계와 개발에 유용하게 적용될 수 있을 것이다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.524-526
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• 2007

Polymer dispersed liquid crystal (PDLC) films consist of micro-droplets of liquid crystals dispersed in a polymer matrix. To make wide area PDLC filled devices, it is necessary to develop reliable method of vacuum injection of PDLC solution instead of the capillary injection. However, well-known 2-ethylhexylacrylate (EHA), main element of a prepolymer, exhibits the volatility problems, when the PDLC solution is placed under the low pressure. In this study, we developed the vacuum injection process to fill a wide area cell. Experimental results indicate that the $V_{90}$(turn-on voltage) of the PDLC cell made by a vacuum injection method are lower than that of the PDLC cell made by a capillary injection method.

• 동력기계공학회지
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• 제17권6호
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• pp.47-53
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• 2013

The article focuses on the Temperature characteristics inside single loop oscillating heat pipe (OHPs). In this paper, heat pipe is experimentally studied thereby providing vital information on the parameter dependency of their thermal performance. The impact depiction has been done for the variation of tube model of the device. OHPs are made of copper capillary tubes of outer diameter 6.25 mm, inner diameter 4 mm heated by constant temperature water bath cooled by ambient temperature. Using four types of OHPs of copper capillary tubes length of 1500mm and HP length 650mm inside tubes working fluid is R-22 Pressure 8 bar and mass 34g,32g,28g,16g. The results indicate a strong influence of filling ratio on the performance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.449-449
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• 2011

We reported the direct effect of intrinsic surface energy of dry adhesive material to the Van der Waals and capillary forces contributions of the total adhesion force in an artificial gecko-inspired adhesion system. To mimic the gecko foot we fabricated tilted nanohairy structures using both lithography and ion beam treatment. The nanohairy structures were replicated from Si wafer mold using UV curable polymeric materials. The control of nanohairs slanting angles was based on the uniform linear argon ion irradiation to the nanohairy polymeric surface. The surface energy was studied utilizing subsequent conventional oxygen ion treatment on the nanohairy structures which resulted in gradient surface energy. Our shear adhesion test results were found in good agreement with the accepted Van der Waals and capillary forces theory in the gecko adhesion system. Surface energy would give a direct impact to the effective Hamaker constant in Van der Waals force and the filling angle (${\varphi}$) of water meniscus in capillary force contributions of gecko inspired adhesion system. With the increasing surface energy, the effective Hamaker constant also increased but the filling angle decreased, resulting in a competition between the two forces. Using a simple mathematical model, we compared our experimental results to show the quantitative contributions of Van der Waals and capillary forces in a single adhesion system on both hydrophobic and hydrophilic surfaces. We found that the Van der Waals force contributes about 82.75% and 89.97% to the total adhesion force on hydrophilic and hydrophobic test surfaces, respectively, while the remaining contribution was occupied by capillary force. We also showed that it is possible to design ultrahigh dry adhesive with adhesion strength of more than 10 times higher than apparent gecko adhesion force by controlling the surface energy and the slanting angle induced-contact line of dry adhesive the materials.

• 한국염색가공학회지
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• 제18권5호
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• pp.61-71
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• 2006

This paper addresses the factors hindering the image quality of lines in inkjet printed on polyester fabric as printing media. Lines were printed onto different types of polyester fabrics in warp and filling directions. Line image quality including line width, edge blurriness, and edge raggedness was assessed. The effect of capillary wicking on line image quality of printed spun polyester fabric is discussed. The factors on the image quality include printing position(top of the yam or between the yarn), printing direction(warp or filling), yarn structures(filament or spun), thread size(yam or fiber), finishing, and ink properties(evaporation rate). More than 30% differences in image quality results were observed by changing the printing location on the spun polyester fabric. The best results of the image quality were obtained with the printed plain and spun polyester fabrics. The fiber sizes may affect capillary size; therefore, the image quality can be dissimilar. Types of finishing materials and inks greatly improve the line image quality on spun polyester fabrics.

• Computers and Concrete
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• 제4권2호
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• pp.157-166
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• 2007

The paper considers a theoretical model to study sulfate ion diffusion in saturated porous media - cement based mineral composites, accounting for simultaneous effects, such as filling micro-capillaries (pores) with ions and chemical products and liquid push out of them. Pore volume change and its effect on the distribution of ion concentration within the specimen are investigated. Relations for the distribution of the capillary relative radius and volume within the composite under consideration are found. The numerical algorithm used is further completed to consider capillary size change and the effects accompanying sulfate ion diffusion. Ion distribution within the cross section and volume of specimens fabricated from mineral composites is numerically studied, accounting for the change of material capillary size and volume. Characteristic cases of 2D and 3D diffusion are analyzed. The results found can be used to both assess the sulfate corrosion in saturated systems and predict changes occurring in the pore structure of the composite as a result of sulfate ion diffusion.

• 성인간호학회지
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• 제16권2호
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• pp.222-232
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• 2004

Purpose: The purpose of this study was to identify the change in foot care knowledge, self care behavior, and physiologic indexes after foot reflexomassage education program, and the related factors. Method: Data were collected from 20 patients who were visited out patients clinic. The change and difference were analyzed with non-parametric statistics. Result: There were significant differences in foot care knowledge(P=.001), self care behavior(P=.000), dosalis pedis blood flow volume (P=.011), skin temperature of foot(P=.001), dorsalis pedis pulse(P=.000), capillary filling time of foot (P=.000) between pre and post. The level of changes of foot care knowledge was significant differences according to admission experience (P=.049), and negative related to systolic blood pressure(P=.028). The level of changes of self care behavior was related to age(P=.049), that of dosalis pedis blood flow was significant difference according to smoking(P=.042), that of skin temperatureof foot(P=.002) and dosalis pedis pulse(P=.038) were significant difference according to weight. The level of changes of capillary filling time of foot was related to diagnosis period(P=.014). Conclusion: Foot-Reflexo-Massage education program is an effective nursing intervention to promote foot care in diabetic patients. And the related factors can be recommended for the management of diabetic patients.

• 대한기계학회논문집A
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• 제27권5호
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• pp.657-665
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• 2003

Several interesting results were obtained from the flow visualization experiment in the accompanying paper, Part I. in the present study, Part II, a numerical study has been carried out to explain the detailed flow phenomena in micro-channel filling process. Hele-Shaw flow approximation was applied to the micro-channel geometry based on the small characteristic length. And surface tension effect has been introduced on the flow front as the boundary condition with the help of a dynamic contact angle concept between the melt front and the wall. A dimensional analysis for numerical results was carried out and a strong relationship between dimensionless pressure and Capillary number is obtained. The numerical analysis results are compared with the flow visualization experimental observations. And the numerical system developed in the present study seems to be able to predict the interesting micro-channel filling flow characteristics observed from experiments.