• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.31-37
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• 2000

In the case of metal-induced lateral crystallization (MILC) for low temperature poly-Si TFT, offset length between Ni-thin film and the sides of gate could be modified to control the location of MILC boundary. Electrical characteristics were compared to analyze the effect of MILC boundary that was located either in or out of the channel region of the TFT. By removing the MILC boundary from channel region, on current, subthreshold slope and leakage current properties could be improved. When MILC boundary was located in the channel region, leakage current was reduced with electrical stress biasing. The amount of reduction increased as the channel width increased, but it was independent of the channel length.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.26-31
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• 2007

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both real density and grain refinement of metallic powders. ECAP (Equal Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method. Effects of processing parameters on densification and density distributions were investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.849-852
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• 2007

We studied ZnO thin films deposited with DC magnetron sputtering for channel layer of TFTs. After analyzing of the basic physical and chemical properties of ZnO thin films, we fabricated a TFTunit test cell. The field effect mobility of $1.8\;cm^2/Vs$ and threshold voltage of -0.7 V were obtained.

• Design & Manufacturing
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• v.16 no.3
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.415-420
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• 2006

Nanostructured metallic materials are synthesized by bottom-up processing which starts with powders for assembling bulk materials or top-down processing starting with a bulk solid. A representative bottom-up and top-down paths for bulk nanostructured/ultrafine grained metallic materials are powder consolidation and severe plastic deformation (SPD) methods, respectively. In this study, the bottom-up powder and top-down SPD approaches were combined in order to achieve both full density and grain refinement without grain growth, which were considered as a bottle neck of the bottom-up method using conventional powder metallurgy of compaction and sintering. For the powder consolidation, equal channel angular pressing (ECAP), one of the most promising method in SPD, was used. The ECAP processing associated with stress developments was investigated. ECAP for powder consolidation were numerically analyzed using the finite element method (FEM) in conjunction with pressure and shear stress.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.88-88
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.05a
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• pp.26.1-26.1
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.896-898
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• 2009

The printed electrodes of organic thin-film transistors (OTFTs) were fabricated by screen printing using nanoparticle silver pastes. The screen printed OTFT corresponds to channel lengths between 7.6 to 82.6 ${\mu}m$ (designed L=10 to 80 ${\mu}m$) on the $150{\times}150mm^2$ paper. The channel length deviations for 40 to 80 ${\mu}m$ patterns were less than 5 %. However, the channel lengths for 10 to 30 ${\mu}m$ patterns were increased by 20 %. The screen printed bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) OTFTs obtained had a field-effect mobility as large as 0.08 (${\pm}0.02$) $cm^2$/Vs, an on/off current ratio of $10^5$ and a subthreshold slope of 1.95 V/decade.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.692-696
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• 2006

Micro fabrication of polymeric materials becomes increasingly important. And it is considered as a low-cost alternative to the silicon or glass-based Micro Electro-Mechanical System(MEMS) technologies. In the present study, micro channels were fabricated via LiGA(Lithographie, Galvanoformung, Abformung) process used for Capillary Electrophoresis(CE) chip. Taguchi method was applied to investigate the effects of process conditions in injection molding(melt temperature, injection speed, mold temperature and packing pressure) on the transcription characteristics of the micro channel. It was found that the skin layer disturbs a formation of micro channel. Furthermore, mold temperature and injection speed were two important factors to affect the replication characteristics of micro channel.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.276-279
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• 2002

A problem formulation and solution for design optimization of laminated composite channel section beam is presented in this study. The objective of this study is the determination of optimum section dimensions of composite laminated channel section beam which has equivalent flexural rigidities to flexural rigidities of steel channel section beam. The analytical model is based on the laminate theory and accounts for the material coupling for arbitrary laminate stacking sequence configuration. The model is used to determine the optimal section dimensions of composite channel section beam. The web height, flange width and thickness of the beam are treated as design variables. The solutions described are found using a global search algorithm, Genetic Algorithms (GA).