• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.468-468
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• 2005

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.834-834
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• 2005

• Journal of Drive and Control
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• v.6 no.2
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• pp.26-33
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• 2009

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.547-554
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• 2004

The surface characteristics of restoration such as surface roughness and droplet contact angle are important part for the process of bacterial adhesion. The purpose of this study is to compare plaque adhesion by measuring roughness, droplet contact angle, and amount of accumulated plaque on the surfaces of composite resins. Four kinds of composite resins, Z-100(Z1), Durafil(DF), Filtek supreme(FS), Clearfil AP X(CA) were used. Ten samples were divided into unpolished and polished group. Surface roughnesses and droplet contact angles were measured by profilometer and goniometer. Plaque weight gains are measured. The results were as follows: 1. The experimental group were rougher than the control group. Surface roughnesses were decreased in the following order; (Z1, DF, CA)>FS in the control group, and CA>Z1>(FS, DF) in the experimental group(P<0.05). 2 The control group showed larger contact angle than the experimental group. Contact angles were decreased in the following order; CA>(FS, DF, Z1) in the control group, and (CA, DF)>(FS, Z1) in the experimental group(P<0.05). 3. The experimental group showed more much plaque than the control group. The amounts of plaque accumulation in vitro were decreased in the following order; Z1>(DF, FS)>CA in the control group, and Z1>FS>(CA, DF) in the experimental group. The latter showed more much plaque than the former(P<0.05). 4. There were stronger correlation between plaque deposition and contact angle (P<0.05) than that of plaque deposition and surface roughness.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.210-211
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• 2005

Desuperheater is a passive device to control the temperature of steam in various plants. However, in spite of its simple structure, the accurate prediction of a desuperheater is very difficult because there are many designed factors for the design of a desuperheater. In this study, the theory of heat transfer phenomena in a desuperheater was developed and the various design factors are evaluated. As a results, we confirmed that the droplet size of 30 - 200 is best effective for the performance of a desuperheater.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.205-213
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• 2005

The drop ejection process from a micro nozzle is investigated by numerically solving the conservation equations for mass and momentum. The liquid-gas interface is tracked by a level set method which is extended for two-fluid flows with irregular solid boundaries. Based on the numerical results, the liquid jet breaking and droplet formation behavior is found to depend strongly on the pulse type of forcing pressure and the contact angle at the gas-liquid-solid interline. The negative pressure forcing can be used to control the formation of satellite droplets. Also, various nozzle shapes are tested to investigate their effect on droplet formation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1441-1444
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• 2007

This paper presents a novel electrostatic drop-an-demand ejector with a conductive pole inside nozzle. The MEMS fabricated pole-type nozzle shows a significant improvement in the performance and reliability of forming meniscus and generating a micro dripping mode of droplet out of the meniscus. It is verified experimentally that the use of the pole-type nozzle. The liquid is used D20+SDS+SWNT (5 %wt). The gap between upper electrode and nozzle is about 600 um. Electrostatic drop-an-demand ejection is observed when a DC voltage of 1.5 kV is applied between the control electrode and ground electrode. Droplet diameter is $100{\mu}m$.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.577-585
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• 2015

We fabricated multi-scale such as macro-, micro-, and multi-scale wrinkles by using repetitive volume dividing (RVD) method and thermal curing process. Also wrinkle surface was modified with coating of a self-assembled monolayer (SAM). We measured the contact angle of each wrinkled surface, and observed the behavior of droplets on sloping surface. Through experimental study, we found out that the contact angle was much higher in case of multi-scale and SAM coated wrinkles. And micro-scale wrinkle showed a high contact angle comparing with that of macro-scale wrinkle. Dynamic behaviors of a water droplet like sliding velocity on diverse wrinkled surfaces were dependent on their static contact angles. These results showed that hydro-dynamic characteristics were changed depending on the wrinkle structure and the material forming the wrinkle. These dynamic characteristics can be utilized in bio-chip, microfluidics, and many others in order to control easily chemical reactivity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.82-88
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• 2003

Four kinds of low calorie mayonnaises containing 1.2% of sodium alginate, 1.0% of guar gum, 1.0% and 1.2% of xanthan gum and one control mayonnaise containing 78.5% of oil without gums were manufactured in pilot scale. Fresh control mayonnaise was higher in viscosity and turbidity than low calorie mayonnaise with gums. During storage at -1$0^{\circ}C$, viscosity and turbidity of control mayonnaise decreased sharply, whereas those of low calorie mayonnaise with gums decreased slightly. Scanning electron microscopy showed that fresh mayonnaise was composed of heterogeneous population of dispersed spherical oil droplets (<10 ${\mu}{\textrm}{m}$), and oil droplet size of control mayonnaise was smaller than any other low calorie mayonnaise. During storage at -1$0^{\circ}C$, a shift in oil droplet size toward larger oil droplets was frequently observed in control mayonnaise as a result of coalescence of oil droplets. Oil separation and turbidimetric study also confirmed that coalescence of oil droplets was occurring during this accelerated aging treatments.

• Journal of Bio-Environment Control
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• v.7 no.4
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• pp.298-310
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• 1998

This research was carried out to find out spray characteristics of 3 types of spray nozzle to be used for greenhouse cooling. Following results were obtained from this experimental study. Water amounts sprayed with each nozzle were increased with the spraying pressure. However the increment of sprayed amount with the increase of spraying pressure were not consistent regardless of nozzle types. For the whole tested spraying pressures of nozzle-type I, II, III, the minimum droplet sizes were about 1.7~2.5$\mu$m, 1.7~2.2$\mu$m and 1.7~2.2$\mu$m, respectively, and the maximum droplet sizes were about 44~60$\mu$m, 52~71$\mu$m and 45~61$\mu$m, respectively, and the average droplet sizes were about 23~38$\mu$m, 19~24$\mu$m and 17~25$\mu$m, respectively The most appropriate spraying pressures of nozzle-type I, II, III were analyzed to be 70kgf/$\textrm{cm}^2$, 30kgf/$\textrm{cm}^2$ and 30kgf/$\textrm{cm}^2$, respectively, and their sprayed amounts were about 124mL/min, 103mL/min and 84mL/min, respectively, and average droplet sizes were 22.6$\mu$m, 21.8$\mu$m and 20.6$\mu$m, respectively. Also, with the order of nozzle-type I, II, III, droplet size distributions less than 30$\mu$m were 95.4%, 85.7% and 79.0%, respectively, and the distributions larger than 40$\mu$m were 0.2%, 1.28% and 1.67%, respectively. However most all of the droplet size were less than 50$\mu$m.