• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.26-30
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• 2023

Interaction of a droplet and substrate is important to determine the coating and final deposition pattern in inkjet printing system. In particular, an accurate deposition of the droplet should be guaranteed for high-resolution patterning. In this study, we performed high-speed shadowgraph experiments on droplet train impact in inkjet system. From the high-speed images, we observed an unexpected bouncing phenomenon. We have found two factors affecting bouncing regime; the Weber number and the curvature of deposited droplet. Experimental results indicate that there is a critical curvature diameter of deposited droplet, which splits into bouncing and merging regime. From this result, we obtained a power-law behavior between the Weber number and the curvature. The understanding of bouncing phenomena helps to improve the accuracy and productivity of inkjet printing.

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.97-106
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• 2019

This study aims to investigate geomorphological and geological landscapes in the Taeanhaean National Park to ensure they are well-preserved. This study discovered 390 geomorphological and geological landform resources distributed in the coastal zone of Taeanhaean National Park. Representative geomorphological and geological landforms include : sea cliffs, sea caves, wave-cut platforms, sea-stacks, pebble beaches, sand beaches, tidal flats, coastal dunes, coastal dune wetlands and folds (or micro folds) landforms. Deposition landforms are developed more and erosion and weathering landforms are less on the land zone than island zone. These landform resources vary from district to district and can be developed for geo-tourism resources. Combined efforts from the Taeanhaean National Park authorities and residents are essential to manage ecological programs using geomorphological and geological resources.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.567-572
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• 2013

In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem, it is difficult to apply to a continuous process such as a R2R(roll to roll) printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, an electrostatic atomizer sprays micro-drops from the solution injected into the capillary with electrostatic force generated by electric potential of about several tens kV. The organic solar cell based on a P3HT/PCBM active layer and a PEDOT:PSS electron blocking layer prepared from ESD method shows solar-to-electrical conversion efficiency of 1.42% at AM 1.5G 1sun light illumination, while 1.86% efficiency is observed when the ESD deposition of P3HT/PCBM is performed on a spin-coated PEDOT:PSS layer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.670-677
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• 1999

An analysis of generation and growth of multicomponent particles has been carried out to predict the size and composition distributions of particles generated in the Modified Chemical Vapor Deposition(MCVD) process. In MCVD process. scale-up of sintering and micro-control of refractive index may need the Information about the size and composition distributions of $SiO_2-GeO_2$ particles that are generated and deposited. The present work solved coupled steady equations (axi-symmetric two dimensions) for mass conservation, momentum balance. energy and species(such as $SiCl_4$, $GeCl_4$, $O_2$, $Cl_2$) conservations describing fluid flow. heat and mass transfer in a tube. Sectional method has been applied to obtain multi-modal distributions of multicomponent aerosols which vary in both radial and axial directions. Chemical reactions of $SiCl_4$ and $GeCl_4$ were included and the effects of variable properties have also been considered.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.123-130
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• 2009

This study presents the application of a polymer behavior model that considers fluid mechanics and heat transfer effects in a deposition system. The analysis of the polymer fluid properties is very important in the fabrication of precise microstructures. This fluid behavior model involves the calculation of velocity distribution and mass flow rates that include the effect of heat loss in the needle. The effectiveness of the proposed method was demonstrated by comparing estimated mass fluid rates with experimental values. The mass fluid rates under various process conditions, such as pressure, temperature, and needle size, reflected the actual deposition state relatively well, and the assumption that molten polycaprolactone(PCL) is a non-Newtonian fluid was reasonable. The successful fabrication of three-dimensional microstructures demonstrated that the model is valid for predicting the polymer behavior characteristics in the microstructure fabrication process. The results of this study can be used to investigate the effect of various parameters on fabricated structures before turning to experimental approaches.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.24-25
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• 2006

In this paper, ZnO thin films were prepared on p-Si(100) by RF magnetron sputtering. Before the depostion, the substrates were pre-heated to 500, 400, 300, $200^{\circ}C$ or not. During the deposition, the substrates were cooled down naturally or kept and then the films were investigated by XRD(X-ray diffraction) and SEM (scanning micro scope). It is showed the most outstanding result that the film was prepared on the substrate were cooled from $400^{\circ}C$. When the substrate was cooled from a certain temperature during deposition, it could be improve the c-axis orientation and useful for application of SAW(surface acoustic wave) filter and FBAR(film bulk acoustic wave resonator) device.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.80-85
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• 2001

$Hg_{1-x}Cd_xTe$(MCT) thin films were grown onto ITO glass and titanium plate by stationary cathodic electrodeposition in aqueous solution contained $CdSO_4$, $TeO_2$, and $HgCl_2$. During deposition two main fabrication parameters were taken into account deposition potential and growth temperature. MCT films deposited by varying two parameters were studied by X-ray diffraction, electron probe micro analyser(EPMA) and scanning electron microscope measurements. It was shown by XRD and EPMA measurements that the structure of MCT films was zinc blonde and the composition of MCT films can be controlled with the deposition potential.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.264-264
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• 2007

$B_2Mg_{2/3}/Nb_{4/3}O_7\;(B_2MN)$ thin films and $Bi_{3/2}MgNb_{3/2}O_7\;(B_{1.5}MN)$ thin films were deposited as a function of various deposition temperatures on Pt/$TiO_2/SiO_2$/Si substrates by radio frequency magnetron sputtering system. Both of their thin films are shown to crystalline phase at $500^{\circ}C$, deposition temperature, using 100W RF power. The composition of them and structural micro properties are investigated by RBS spectrum and SEM, AFM. 200 nm-thick $B_2MN$ thin films were deposited at room temperature had capacitance density of $151nF/cm^2$ at 100kHz, dissipation factor of 0.003 and had capacitance density of $584nF/cm^2$ at 100kHz, dissipation factor of 0.0045 at $500^{\circ}C$ deposition temperature. Both of their dielectric constant deposited at room temperature and at $500^{\circ}C$ were each approximately 40 and 100.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.140.2-140.2
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• 2013

Strong metal-support interaction effect is an important issue in determining the catalytic activity for heterogeneous catalysis. In this work, we report the catalytic activity of $Au/TiO_2$, $Au/Al_2O_3$, and $Au/Al_2O_3-CeO_2$ nanocatalysts under CO oxidation fabricated by arc plasma deposition (APD), which is a facile dry process with no organic materials involved. These catalytic materials were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and $N_2$-physisorption. Catalytic activity of the materials has measured by CO oxidation using oxygen, as a model reaction, in a micro-flow reactor at atmospheric pressure. Using APD, the catalyst nanoparticles were well dispersed on metal oxide powder with an average particle size (3~10 nm). As for catalytic reactivity, the result shows $Au/Al_2O_3-CeO_2$ nanocatalyst has the highest catalytic activity among three samples in CO oxidation, and $Au/TiO_2$, and $Au/Al_2O_3$ in sequence. We discuss the effects of structure and metal-oxide interactions of the catalysts on catalytic activity.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.98-102
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• 2008

The ferroelectric properties of UV irradiated and non-irradiated PZT films prepared via photochemical metal-organic deposition using photosensitive precursors were characterized. Fourier transform infrared spectroscopy showed that complete removal of organic groups was possible through UV exposure of the spin-coated PZT precursor films at room temperature. The measured remnant polarization values of UV-irradiated and non-irradiated PZT films after annealing at $650^{\circ}C$ were 29 and $23\;{\mu}C/cm^2$, respectively. The UV irradiation was found to be effective for the enhancement of the <111> growth orientation and ferroelectric property of PZT film and in the direct patterning in the fabrication of micro-patterned systems without dry etching.