• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.633-638
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• 2012

The maximum spreading is the maximum extent to which a drop can spread after impacting on a surface. It is one of the crucial factors determining the spraying performance in many applications. In this study, the existing maximum spreading models for a Newtonian liquid droplet impacting on a dry solid surface were reviewed and compared with the experimental results over the ranges of $4{\leq}Re{\leq}11700$, $23{\leq}We{\leq}786$, and $37.9^{\circ}{\leq}{\theta}_s{\leq}107.1^{\circ}$. The surface wettability was found to have only a minor influence on the maximum spreading, compared to the liquid viscosity and impact velocity. Among the models tested, the Roisman (2009) model showed the best agreement with the experimental results, matching 80% of the measured data within ${\pm}5%$.

• Food Science of Animal Resources
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• v.33 no.1
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• pp.67-74
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• 2013

The aims of this research were to produce oil-in-water ${\beta}$-lactoglobulin/alginate (${\beta}$-lg/Al) nanoemulsions loaded with coenzyme $Q_{10}$ and to investigate the combined effects of heating temperature and alginate concentration on the physicochemical properties and encapsulation efficiency of ${\beta}$-lg/Al nanoemulsions. In ${\beta}$-lg/Al nanoemulsions production, various heating temperatures (60, 65, and $70^{\circ}C$) and alginate concentrations (0, 0.01, 0.03, and 0.05%) were used. A transmission electron microscopy was used to observe morphologies of ${\beta}$-lg/Al nanoemulsions. Droplet size and zeta-potential values of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$ were determined by electrophoretic light scattering spectrophotometer and HPLC, respectively. The spherically shaped ${\beta}$-lg/Al nanoemulsions with the size of 169 to 220 nm were successfully formed. The heat treatments from 60 to $70^{\circ}C$ resulted in a significant (p<0.05) increase in droplet size, polydispersity, zeta-potential value of ${\beta}$-lg/Al nanoemulsions, and encapsulation efficiency of coenzyme $Q_{10}$. As alginate concentration was increased from 0 to 0.05%, there was an increase in the polydispersity index of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$. This study demonstrates that heating temperature and alginate concentration had a major impact on the size, polydispersity, zeta-potential value and encapsulation efficiency of coenzyme $Q_{10}$ in ${\beta}$-lg/Al nanoemulsions.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.308-312
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• 2022

3D printing technology, which creates a physical object by various material deposition, has been widely used in recent years in the manufacturing field because of its advantages. Among the various printing technologies, droplet-based 3D printing technology (e.g., Polyjet^®) enables a high-resolution printing using photocurable materials such as hydrogels. Depending on the degree of light exposure, ejected photocurable droplets may have different properties (e.g., viscosity) until they collide with the substrate and it leads to the different spreading behaviors of the droplets (i.e., impact, spreading, and recoiling) during deposition on the substrate. In this study, experimental observation and analysis of the changes in hydrogel droplet viscosity and spreading behavior according to the light exposure were carried out based on high-speed image processing.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1317-1322
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• 2004

In this report, the heat transfer model of spray cooling on hot surface was developed by focusing on the effect of rebound motion of droplets. In the model, it was assumed that droplets rebound repeatedly on the hot surface and heat transfer upon droplet impact is proportional to sensible heat which heats up the droplets to the saturation temperature. In addition, to take account of the contribution of th heat flux upon impact of rebound droplets, it was assumed that the rebound droplets are distributed following the Gaussian distribution from 0 to L, which distance L is determined by maximum flight distance $L_{max}$. Also the calculated results were compared with existing experimental results.

• Journal of ILASS-Korea
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• v.24 no.1
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• pp.8-14
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• 2019

The purpose of this study is to develop a packing-free wet scrubber to prolong the maintenance interval compared with the conventional packed bed wet scrubbers with which frequent operation stops are unavoidable to clean the packing materials. The main- and interaction-effects were quantitatively analyzed by regression analysis for the measured ammonia scrubbing data from the experiments prepared by experimental design. The scrubbing efficiency of the newly developed wet scrubber was found to be over 95% under the condition of flue gas flow rate of 90CMM and liquid-to-gas ratio $2l/m^3$ for all considered trials of experimental design. The interaction effect between the inlet duct spray and the filter was found to be important, which controls the droplet growth due to the droplet collisions between the duct- and scrubbing tower-spray. The presented methodology to analyze the impacts of operational and design factors on the scrubber efficiency showed potential for applications to optimize the future flue gas abatement process in semiconductor plants.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.93-99
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• 1998

The effects of welding conditions of gas metal arc welding on the elements loss of solid wire, oxygen content and impact toughness of weld metals were studied. Deoxidizing elements loss was increased with increase of arc voltage in both short-circuit transfer mode and globular transfer mode. It is believed that increase of arc voltage results in increase of reaction time between elements in the droplet and surrounding gas at the end of wire and in the arc column. Based on the thermodynamic equilibrium model, the oxygen content of weld metal can be predicted with the content of silicon and manganese as following : [%O] = $K([%Si][%Mn])^{-0.25}$, K = -15518/T+6.01. The equilibrium temperature was dependent on shielding gas, and it was 187$0^{\circ}C$ for $CO_2$ gas and 180$0^{\circ}C$ for 20%$CO_2$-80%Ar gas. The oxygen content of weld metal which shows maximum impact toughness was varied with deoxidizing alloy system of wires, 0.041 wt% for Si-Mn type wire and 0.026 wt% for Si-Mn-Ti type wire.

• Journal of ILASS-Korea
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• v.4 no.4
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• pp.30-37
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• 1999

The breakup characteristics of liquid sheet formed by the liquid rocket injector has a close relation with the combustion efficiency. In this paper, basic characteristics of droplet size and velocity distribution were measured with PDPA for the Like Doublet Impinging Injector. Test variables were the angle of impact, the diameter of orifice and jet velocity. Water was used as test fluid. As a result, for impingement angle less than 90 degree, following correlations were obtained between drop size and design parameters : $D_{32}({\mu}m)=295.0{\times}V^{-0.09}\times(2\theta)^{-0.1}{\times}d^{0.072}$. For impingement angle greater than 100 degree, drop sizes were increased but eventually converged to a certain limiting value.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.102-110
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• 2023

With the global shift from a carbon-based economy to a hydrogen-based economy, understanding the sloshing phenomenon and its impact on boil-off rate (BOR) in liquid hydrogen (LH2) tank trailers is crucial. Here, we analyze the primary breakup process under sloshing phenomena in a liquid fuel tank. We observe the growth of multiple holes on the sheet-like structures and the formation of ligament structures reminiscent of jet atomization. Through the extraction of three-dimensional liquid regions, we analyze the geometrical characteristics of these regions, enabling the classification of sheets, ligaments, and droplets. The present findings could contribute to understanding the breakup mechanism and hold potential for the development of strategies aimed at minimizing BOR.

• Journal of Genetic Medicine
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• v.20 no.2
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• pp.46-51
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• 2023

Exonic copy number variation (CNV), involving deletions and duplications at the gene's exon level, presents challenges in detection due to their variable impact on gene function. The study delves into the complexities of identifying large CNVs and investigates less familiar but recurrent exonic CNVs, notably enriched in East Asian populations. Examining specific cases like DRC1, STX16, LAMA2, and CFTR highlights the clinical implications and prevalence of exonic CNVs in diverse populations. The review addresses diagnostic challenges, particularly for single exon alterations, advocating for a strategic, multi-method approach. Diagnostic methods, including multiplex ligation-dependent probe amplification, droplet digital PCR, and CNV screening using next-generation sequencing data, are discussed, with whole genome sequencing emerging as a powerful tool. The study underscores the crucial role of ethnic considerations in understanding specific CNV prevalence and ongoing efforts to unravel subtle variations. The ultimate goal is to advance rare disease diagnosis and treatment through ethnically-specific therapeutic interventions.

• Journal of ILASS-Korea
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• v.29 no.2
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• pp.91-97
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• 2024

When investigating the droplet, spray, and impact of liquid on a solid plate, backlight imaging has been widely used to understand these phenomena. However, some previous studies have suffered from poor image quality. In this study, various combinations of image processing algorithms, such as white image correction, histogram equalization, CLAHE, Otsu's binarization, and multi-Otsu's binarization, have been applied to flash boiling spray images to enhance image quality for qualitative observation and semi-quantitative spray angle evaluation. To acquire images with high contrast for qualitative observation, applying CLAHE was effective, making small droplets and detailed shapes of the jet noticeable. However, when images were averaged to determine spray angle or penetration length based on intensity, this method induced artifact unphysical patterns, thus requiring careful consideration. Based on the algorithm proposed in this study, the spray angle variation according to injection pressure and temperature has been calculated, showing a reasonable trend.