• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1173-1179
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• 2007

In recent years, research to machine large-surface micro-features has become important because of the light guide panel of a large-scale liquid crystal display and the bipolar plate of a high-capacity proton exchange membrane fuel cell. In this study, in order to realize the systematic design technology and performance improvements of an ultra-precision machine for machining the large-surface micro-features, a structural characteristic analysis was performed using its virtual prototype. The prototype consisted of gantry-type frame, hydrostatic feed mechanisms, linear motors, brushless DC servo motor, counterbalance mechanism, and so on. The loop stiffness was estimated from the relative displacement between the tool post and C-axis table, which was caused by a cutting force. Especially, the causes of structural stiffness deterioration were identified through the structural deformation analysis of sub-models.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.43-50
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• 2016

This research proposal is based on a novel non-contact technique of micro-sized bead injection process for fabrication of electronic paper display. This non-contact injection process is based on the principle of electrostatic force and uses micro-sized metal-coated beads dispersed in a solution. The dispersion retention times of three different solutions with viscosities of 10 cps, 100 cps, and 1000 cps were measured by optical equipment showing the retention times of 5 mins, 10 mins, and 30 mins respectively. The dispersion retention rate dropped as the time passed. The dispersion retention characteristic of 1000 cps solution was more stable as compared to those of 10 cps and 100 cps meaning that higher viscosity has better retention properties. The experimental results of bead injection at different viscosity levels of the solution were also measured and a stable injection result was achieved by using 1000 cps solution. This results show that stable injection is dependent on solution viscosity and dispersion.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.171-176
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• 2001

Plasma Display Panel(PDP) is a type of flat panel display utilizing the light emission produced by gas discharge. Barrier Ribs of PDP separating each sub-pixel prevents optical and electrical crosstalks from adjacent sub-pixels. Mold for forming barrier ribs has been newly researched to overcome the disadvantages of conventional manufacturing process such as screen printing, sand-blasting and photosensitive glass methods. Mold for PDP barrier ribs have stripes of micro grooves transferring glass-material wall. In this paper, Stripes of grooves of which width 48${\mu}{\textrm}{m}$ and 270${\mu}{\textrm}{m}$, depth 124${\mu}{\textrm}{m}$, pitch 274${\mu}{\textrm}{m}$ was acquired by machining hard and brittle materials of WC, Silicon, Alumina with dicing saw blade. Maximum roughness of the bottom and sidewall of the grooves was respectively 120nm, 287nm in grooving WC. Maximum tilt angle caused by difference between upper-most width and lower-most width was 2$^{\circ}$. Maximum Radius of bottom curvatures was 7.75${\mu}{\textrm}{m}$. This results satisfies the specification for barrier ribs of 50 inch XGA PDP if the groove form of mold was fully transferred to the barrier ribs. Barrier ribs were formed with Silicone rubber mold, which is transferred from grooved hard materials. Silicone rubber mold has elasticity accommodating the waveness of lower glass plate of PDP.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.161-166
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• 2005

The plasma ion density in AC-PDP has shown to be increased from $5.6{\times}10^{11}cm^{-3}$ to $9.0{\times}10^{11)cm^{-3}$ as the Xe mixture ratio to neon increase from 1 % to 10 %, respectively, at fixed pressure of 400 Torr, by using the micro-Langmuir probe. It is noted that the plasma ion density is density increases as the gas pressure increases in this experiment. The electron temperature decreases from 2.3 to 1.2 eV as the Xe mole fraction increases from 1 % to 10 % at fixed pressure of 400 Torr, which is measured by the micro Langmuir probe and high-speed ICCD camera in this experiment. It is noted that the electron temperature decreases as the gas pressure increases from 150 to 400 Torr in this experiment. It is also observed that the exited Xe atom density and the plasma ion density are in strong correlation sharp between each other in this experiment. It is noted that $5.2{\times}10^{12}cm^{-3}$ in the $1s_5$ metastable state and $1.2{\times}10^{12}cm^{-3}$ in the $1s_4$ resonance state for the PDP cell with gap of 50 um distances under the fixed gas pressure of 400 Torr and Xe content ratio of 10 %.

• Journal of Powder Materials
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• v.20 no.5
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• pp.355-358
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• 2013

Micro trench structures are applied in gratings, security films, wave guides, and micro fluidics. These micro trench structures have commonly been fabricated by micro electro mechanical system (MEMS) process. However, if the micro trench structures are machined using a diamond tool on large area plate, the resulting process is the most effective manufacturing method for products with high quality surfaces and outstanding optical characteristics. A nonferrous metal has been used as a workpiece; recently, and hybrid materials, including polymer materials, have been applied to mold for display fields. Thus, the machining characteristics of polymer materials should be analyzed. In this study, machining characteristics were compared between nonferrous metals and polymer materials using single crystal diamond (SCD) tools; the use of such materials is increasing in machining applications. The experiment was conducted using a square type diamond tool and a shaper machine tool with cutting depths of 2, 4, 6 and 10 ${\mu}m$ and a cutting speed of 200 mm/s. The machined surfaces, chip, and cutting force were compared through the experiment.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.596-601
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• 2004

In this paper, we describe a study on the influence of the frequency variation of normal vibration using an integrated tactile display. It is necessary to consider this study because we want to find a method of displaying finer texture and know that the perception of fine textures is heavily influenced by temporal variation. Our tactile display system used in this experiment can simulate the micro shapes and roughness of surface textures by individual drives of a 6x8 pin array. Two experiments are performed. The first is a psychophysical experiment on the definition and range decision of roughness, and through the experiment, we clear up the meaning of roughness. The second is the main experiment about the frequency variation of normal vibration. We find the correlation between the vibration frequency and the texture and the condition for better display and perception of fine surfaces. The experimental results yielded two pieces of information. One is that lateral movement affects texture discrimination, and another is that normal vibration can make the perceived texture feel finer than real texture. That is, the vibrating stimulus is more effective for displaying a fine surface than static pressure, and it makes possible to display finer texture, exceeding the physical limit of the device.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.392-392
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• 2011

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission.$^{1,2}$ CNT yarns have demonstrated its potential as excellent field emitters.$^3$ Extensive simulations were carried out in designing a CNT yarn-based cathode assembly. The focal spot size dependence on the anode surface of the geometric parameters such as axial distance of the electrostatic focus lens from the cathode and the applied bias voltages at the cathode, grid mesh and electrostatic focus lens were studied. The detailed computer simulations using Opera 3D electromagnetic software$^4$ had revealed that a remarkable size of focal spot under a focusing lens triode type set-up design was achieved. The result of this optimization simulation would then be applied for the construction of the CNT yarn based micro-focus x-ray tube with its field emission characteristics evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.674-680
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• 2017

Touch Screen Panel (TSP) is a widely used personal handheld device and as a large display apparatus. This study examines micro bump fabrication technology for TSP test process. In the testing process, as TSP is changed, should make a new micro bump for probing and modify the testing program. In this paper we use a maskless lithography system to confirm the potential to fabricatemicro bump to reducecost and manufacturing time. The requiredmaskless lithography system does not use a mask so it can reduce the cost of fabrication and it flexible to cope with changes of micro bump probing. We conducted electro field simulation by pitches of micro bump and designed the lithography pattern image for the maskless lithography process. Then we conducted Photo Resist (PR) patterning process and electro-plating process that are involved in MEMS technology to fabricate micro bump.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.552-554
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• 2004

Barrier ribs of plasma display panel (PDP) are glass matrix composite reinforced with alumina particles. Mechanical properties of the ribs are very crucial for the improvement in reliability of the panel as the ribs might fracture during transportation and service. In this study, therefore, the effects of filler type and content on the mechanical properties of the ribs were investigated. The fillers used include $Al_2O_3$, $TiO_2$, $ZrO_2$ and fused silica. The content of the filler was changed from 0 to 40 vol.%. The mechanical properties of the ribs measured were hardness, Young's modulus, fracture toughness, and 3-point bending modulus. The fracture toughness evaluated by micro-Vicker's indentation of the composites, in general, was measured to increase with the content of the filler until the sintered density does not decrease significantly. The improvement, however, was dependent on the type of filler employed.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.2009-2015
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• 2017

A two-dimensional lens is required to reproduce both the horizontal and vertical parallax through an autostereoscopic 3D display. Among the two-dimensional lenses, a hexagonal micro lens array (MLA) having good optical efficiency is mainly used. However, the hexagonal MLA has complex geometric features. The first feature is that the lens cells are zigzagged in the vertical direction, which should be reflected in the view number calculation for each sub-pixel. The second feature is that the four sides of a hexagonal lens cell are tilted, requiring a more careful view index assignment to the lens cell. In this paper, we propose a sub-pixel multiplexing scheme suitable for the features of the hexagonal MLA. We also propose a view-overlay algorithm based on a two-dimensional lens and compare subjective image quality with existing view-selection through autostereoscopic 3D display implementation.