• Journal of the Korean Graphic Arts Communication Society
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• v.6 no.1
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• pp.67-74
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• 1988

Absorption rates of oxygen in water soluble inks on the printing rollers were measured. As a results of experiments, could be obtained the data of rates of absorption of oxygen in 4 kinds of water soluble inks, and found the difference of absorption rate of oxygen on the parallel plates and rotating rolles.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.687-687
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• 2013

In rearpoint contact solar cell and the PERC (passivated emitter rear contact) type cell, surfaces were passivated by SiO2 or Al2O3 to increase solar cell efficiency. Therefore, we have investigated the effect of surface passivation for crystalline silicon solarcell using mass-production atomic layer deposited (ALD) Al2O3. The patttern which consists of cylinders with 100um diameter and 5um height was formed by PR patterning on Si (100) substrate and then Al2O3 of about 10nm and 20nm thickness was deposited by ALD. The pattern in 10 nm Al2O3 film was removed by dipping in aceton solution for about 10 min but the pattern in 20 nm Al2O3 film was not. The influences of process temperature and heat treatment were investigated using microwave photoconductance decay (PCD) and Quasi-Steady-State photoconductance (QSSPC). The solar cell process used in this work combines the advantage of using the applicability of a selective deposition associated with a ALD passivation and the use of low-cost screen print for the contacts formation.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.354-359
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• 2006

Recently, the interest in lithography without photo exposure has been increased compare to the conventional photolithography in nano meter and micrometer size patterning area. We studied a self aligned dipping of Ag solution through micro contact printing (${\mu}-CP$) with octadecyltrichlorosilane (OTS) treated polydimethylsiloxane (PDMS) soft mold. The OTS monolayer on the patterned PDMS was formed by dipping it into OTS solution. We transferred the OTS monolayer from PDMS mold to the glass. The OTS monolayer changed the surface energy from hydrophilic surface to hydrophobic surface, And then we made self aligned Ag solution patterns just after dipping the substrate, using adhesion difference of Ag solution between OTS treated hydrophobic area and non-OTS treated hydrophilic area. We finally get the Ag patterns through only dip-coating after the ${\mu}-CP$ process. And we observed surface energies on the glass substrate through the contact angle measurements as time goes on.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2075-2082
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• 2006

This paper presents modeling and optimization techniques for hish efficiency solar cell process on single-crystalline float zone (FZ) wafers. Among a sequence of multiple steps of fabrication, the followings are the most sensitive steps for the contact formation: 1) Emitter formation by diffusion; 2) Anti-reflection-coating (ARC) with silicon nitride using plasma-enhanced chemical vapor deposition (PECVD); 3) Screen-printing for front and back metalization; and 4) Contact formation by firing. In order to increase the performance of solar cells in terms of efficiency, the contact formation process is modeled and optimized using neural networks and genetic algorithms, respectively. This paper utilizes the design of experiments (DOE) in contact formation to reduce process time and fabrication costs. The experiments were designed by using central composite design which consists of 24 factorial design augmented by 8 axial points with three center points. After contact formation process, the efficiency of the fabricated solar cell is modeled using neural networks. Established efficiency model is then used for the analysis of the process characteristics and process optimization for more efficient solar cell fabrication.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.345-351
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• 2019

Recently, ink-jet printing technology has been applied for various industries such as semiconductor, display, ceramic tile decoration. Ink-jet printing has advantages of high resolution patterning, fast printing speed, high ink efficiency and many attempts have been made to apply functional materials with excellent physical and chemical properties for the ink-jet printing process. Due to these advantages, research scope of ink-jet printing is expanding from conventional two-dimensional printing to three-dimensional printing. In order to expand the application of ink-jet printing, it is necessary to optimize the rheological properties of the ink and the interaction with the substrate. In this study, photo curable ceramic complex ink containing nano silica particles were synthesized and its printability was characterized. Contact angle of the photo curable silica ink were modified by control of the ink composition and the surface property of the substrate. Effects of contact angle on printing resolution and three-dimensional printability were investigated in detail.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.1
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• pp.43-52
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• 2007

Offset printing is one of the well known printing technique of lithographic process and consists of image area and 'non-image area on a flat image carrier. The surface tension of dampening water can be controlled by adding IPA after mixing of raw water and etching solution. The etching solution contains a surfactant for reducing surface energy, a clean agent for non-imaging area, wetting agent for protecting non-imaging area from oil components like ink and also an emulsifying agent for controlling emulsification. In this study, the present situation of dampening water maintenance has examined by collecting dampening water using at domestic companies. The pH related to dampening water, conductivity, contact angle, emulsification curve are measured to define the current situation of dampening water control of each companies and to analyze the relationship among measured properties. In the study most of companies among 16 printing companies tested controlling dampening water through pH value. However, the quality of printing has varied depending upon conductivity, contact angle, IPA content, and emulsification value. The control of dampening water should be carry at the state of the standard when adding proper ratio of etching solution. It would be more effective when pH or conductivity control carries out in parallel with controlling dampening water. Therefore the concept that pH5.5 is correct is based concept. Based on these initial tests it is defined that the standardization of dampening water control is required.

• Electronic Materials Letters
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• v.14 no.6
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• pp.718-724
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• 2018

With the development of photovoltaic industry, the cost of photovoltaic power generation has become the significant issue. And the metallization process has decided the cost of original materials and photovoltaic efficiency of the solar cells. Nowadays, double printing process has been introduced instead of one-step printing process for front contact of polycrystalline silicon solar cells, which can effectively improve the photovoltaic conversion efficiency of silicon solar cells. Here, the relative cheap Cu paste has replaced the expensive Ag paste to form Ag/Cu composite front contact of silicon solar cells. The photovoltaic performance and the cost of photovoltaic power generation have been investigated. With the optimization on structure and height of Cu finger layer for Ag/Cu composite double-printed front contact, the silicon solar cells have exhibited a photovoltaic conversion efficiency of 18.41%, which has reduced 3.42 cent per Watt for the cost of photovoltaic power generation.

• Textile Coloration and Finishing
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• v.25 no.4
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• pp.287-291
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• 2013

Nowadays, terms such as 'Smart Textile', 'Intelligent Textile' and 'Wearable Computing' are commonly used in everyday contexts. And radio-frequency identification (RFID) is the use of a wireless non-contact system that uses radio-frequency electromagnetic fields to transfer data from a tag attached to an object, for the purposes of automatic identification and tracking. These products are required technologies which are textile treatments, printing, ink, etc. Durability of textile substrates is an essential marker for conductive ink printing process. Especially, heat stability is important, since conductive ink should be processable (annealing, curing) at temperatures below $150^{\circ}C$. This study was application of RFID on textiles. The textile pre-treatment processes should be carried out to use RFID antenna on textiles.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1457-1458
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• 2009

The fundamental parameters controlling ink-jet printing liquids are the viscosity and surface energy. The wetting contact angle determines the spread of a liquid drop on the surface and depends on the relative surface energy. The characteristics of silver ink-jet printing were studied with control of surface energy and head temperature. Polyethylene terephthalate(PET) film and Si-wafer(ptype) were used as substrates and atmospheric plasma was treated to control the surface energy. With silver ink, the hydrophilic surface treatment could reduce the radius of droplets due to the hydrophobic nature of silver ink.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.13.2-13.2
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• 2009

Electrostatic printing either it is drop-on-demand or continuous has immense applications in non-contact printing systems such as solar cells, flexible printed circuits, RFIDs and bio applications. In this paper a laboratory manufactured nozzle has been designed for the experimental investigation of electrostatic dripping and atomization of liquid. Dripping and atomization conditions such as voltage, nozzle tip diameter, distance between counter electrode and flowrate has been indentified for the designed nozzle. Furthermore it is also demonstrated that the diameter of a generated droplet could be reduced from a significantly large size to a narrow size distribution which can be controlled by volumetric flow rate and applied voltage. This study will help in classify the conditions between different electrostatic dripping mode such as drop-on-demand formation, jet mode and finally the atomization mode based on the laboratory fabricated nozzle head.