• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.667-670
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• 2002

Uniform metal-droplet deposition using laser is analyzed. Using the variation principle and modeling the semi-solid phase as a non-Netwonian slurry, this model can greatly save the computational expenses that conventional numerical procedures have suffered from. The simulation results revealed that the developed model could reasonably describe the collision behavior of molten metal with solid surface. Simulations were made with variation of the falling distance and time.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.165-172
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• 2018

As an approach for estimation of the droplet size in the molten salt-liquid metal extraction process, a droplet formation experiment at room temperature was conducted to evaluate the applicability of the Scheele-Meister model with water-mercury system as a surrogate that is similar to the molten salt-liquid metal system. In the experiment, droplets were formed through the nozzle and the droplet size was measured using a digital camera and image analysis software. As nozzles, commercially available needles with inner diameters (ID) of 0.018 cm and 0.025 cm and self-fabricated nozzles with 3-holes (ID: 0.0135 cm), 4-holes (ID: 0.0135 cm), and 2-holes (ID: 0.0148 cm) were used. The mercury penetration lengths in the nozzles were 1.3 cm for the needles and 0.5 cm for the self-fabricated nozzles. The droplets formed from each nozzle maintained stable spherical shape up to 20 cm below the nozzle. The droplet size measurements were within a 10% error range when compared to the Scheele-Meister model estimates. The experimental results show that the Scheele-Meister model for droplet size estimation can be applied to nozzles that stably form droplets in a water-mercury system.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.187-193
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• 2005

The temperature distribution of the deposited droplet was predicted by using the finite element analysis and it was assumed that the droplet was axisymmetrical model. The analysis of residual stress was performed with the temperature data, which is obtained from the result. Axisymmetric droplet is deposited three times to consider the actual phenomenon of droplet deposition. The analysis of the temperature distribution is respectively performed whenever the axisymmetric droplet is laminated and the residual stresses of the laminated axisymmetric droplet are calculated with the value of the temperature distribution.

• Proceedings of the KWS Conference
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• 2000.04a
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• pp.105-108
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• 2000

• Proceedings of the Korean Society of Laser Processing Conference
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• 2003.05a
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• pp.122-126
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• 2003

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1550-1551
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• 2007

노즐 직경 $30\;{\mu}$인 MEMS 압전 잉크젯 헤드를 이용하여 Ag 나노 잉크를 PDMS 처리된 PI(Polyimide) 기판 위에 토출하였다. 구동주파수 5 KHz에서 액적부피 1.5 pl, 속도가 약 4.5 m/s인 액적이 토출 되었다. 인쇄된 액적의 크기는 직경 약 $12\;{\mu}m$이었다. 메니스커스의 거동에 맞춘 구동파형의 입력에 의해 새틀라이트 없는 매우 작은 액적을 토출할 수 있었다.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.214-219
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• 2001

In this study, numerical investigation has been performed on the spreading and solidification of a droplet impacting onto a solid substrate in the thermal spray process. The finite difference method with volume-of-fluid approach is used to analyze the free surface flow and the source-based enthalpy method is employed to model the latent heat release during the solidification. In this work, the numerical model is validated through the comparison of the present numerical result with experimental data available for the flat substrate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1597-1604
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• 2002

In this study, numerical investigation has been performed on the impingement, spreading and solidification of a coating material droplet impacting onto a solid substrate in the thermal spray process. The numerical model is validated through the comparison of the present numerical result with experimental data fer the flat substrate without surface defects. An analysis of deposition formation on the non-polished substrate with surface defects is also performed. The parametric study is conducted with various surface defect sizes and shapes to examine the effect of surface defects on the impact and solidification of the liquid droplet on the substrate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.689-693
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• 2005

Inkjet printing is a non-contact and direct writing associated with a computer. In the industrial field, there have been many efforts to utilize the inkjet printing as a new way of manufacturing, especially for electronic devices. For the application of inkjet printing to electronic field, one of the key factors is exact realization of designed images into printed patterns. In this work, micro patterning for conducting line has been studied using the piezoelectric print head and silver nano ink. Dimensions of printed images have been predicted in terms of print resolution and diameter of a single dot. The predicted and the measured values showed consistent results. Using the results, the design capability for industrial inkjet printing could be achieved.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.593-602
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• 2016

Numerical simulations on the close-coupled supersonic gas atomizer for metallic powder production were performed in this study. A proper turbulence model was chosen and then VOF(Volume of Fluid) and DPM(Discrete Phase Model) methods were sequentially applied for the simulations of primary and secondary break-up processes of liquid metal. Diameters of parent droplets were calculated by analyzing Level-Set function contour from the VOF result. Finally, the distribution of particle diameter was obtained from the DPM result at exit of the computational domain.