• Journal of the Semiconductor & Display Technology
• /
• v.22 no.4
• /
• pp.119-123
• /
• 2023

This study is normal orientation technology of slit coating equipment to improve the quality of curved displays. Currently, the demand for curved displays is increasing significantly due to advantages such as screen immersion or design in various industries. Accordingly, changes in the display coating process are essential. In the curved display coating process, unlike the existing flat coating process, the nozzle must be rotated along the curvature of the curved surface to spray the coating solution. The coating solution must be applied while maintaining a uniform thickness. If the thickness of the coating liquid applied to the target surface is non-uniform, the quality of the product may be degraded such as image quality deterioration and light spreading. This paper presents technology and experimental results for keeping the nozzle of slit coating equipment perpendicular to the curved surface and is expected to contribute to the quality improvement of curved displays.

• Tribology and Lubricants
• /
• v.30 no.1
• /
• pp.59-63
• /
• 2014

Laser Surface Texturing(LST) is a surface engineering process used to improve tribological characteristics of materials by creating patterned microstructures on the mechanical contact surface. In LST technology, a pulsated laser beam is used to create arranged dimples on a surface by a material ablation process, which can improve such as load capacity, wear resistances, lubrication lifetime, and reduce friction coefficients. In the present study, the effect of multi-scale LST on lubricant regime was investigated. A pulsed Nd:YAG laser was applied on the bearing steel(AISI 52100) to create arranged dimples. To optimize the surface texturing effect on friction, multi-scale texture dimples with some specific formula arrays were fabricated by combining circles, ellipses and the laser ablation process. The tribological testing of multi-scale textured surface was performed by a flat-on-flat unidirectional tribometer under lubrication and the results compared with that of the non-textured surface. Through an increase in sliding speed, the beneficial effect of multi-scale LST performance was achieved. The multi-scale textured surface had lower friction coefficient performances than the non-textured surface due to the hydrodynamic lubrication effect.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.217-220
• /
• 2009

This paper presents fabrication method of nano-structured PMMA substrates as well as evaluations of their optical transmittance. For anti-reflective surface, surface coating method had been conventionally used. However, it requires high cost, complicated process and post-processing times. In this study, we suggested the fabrication method of anti-reflective surface by the hot embossing process. Using the nano patterned master fabricated by anodic aluminum oxidation process. Anodic aluminum oxide(AAO) is widely used as templates or a molds for various applications such as carbon nano tube (CNT), nano rod and nano dots. Anodic aluminum oxidation process provides highly ordered regular nano-structures on the large area, while conventional pattering methods such as E-beam and FIB can fabricate arbitrary nano-structures on small area. We fabricated a porous alumina hole array with various inter-pore distance and pore diameter. In order to replicate nano-structures using alumina nano hole array patterns, we have carried out hot-embossing process with PMMA substrates. Finally the nano-structured PMMA substrates were fabricated and their optical transmittances were measured in order to evaluate the charateristivs of anti-reflection. Anti-reflective structure can be applied to various displays and automobile components.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1690-1697
• /
• 2002

The effects of re-peening on the fatigue damaged material are studied in this paper. The effects of re-peening process on surface hardness, surface roughness, surface compressive residual stress, and fatigue life are investigated. The results can be summarized in brief as follows: The depth of hardening layer was increased by re-peening process. There is no large variation of the surface roughness by re-peening process. The compressive residual stress of shot-peened specimen decreases under the fatigue loading and then increases again by re-peening process. Re-peening process increases the fatigue lifo of shot-peened and fatigue damaged specimen. The increase of fatigue lift under high stress level is much higher than under low stress level.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.8 no.2
• /
• pp.46-52
• /
• 2009

Drilling operation is such an important machining process, which has been wildly applied to the industry, occupied over 30% of whole industry. However, there are many aspects of drilling process should be improved, such as increases of thrust force, surface roughness, and roundness, ect. In this study, we are aiming to reduce the thrust force, surface roughness, and roundness in drilling process. For this purpose, multi facet drills (MFD) of three types that are modified from standard drill (STD) are developed. The first type is multi stair drill (MSD) with shape of stair on relief plane. The second type is rough facet drill (RFD) with shape of round on relief plane. The third type is rough flute drill (RFLD) with shape of round on flute plane. For three types of MFD, we were carried out performance evaluation from the perspective of thrust force, surface roughness and roundness of machined hole. From obtained result, we could confirmed that performance of rough flute drill (RFLD) type is most excellent.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.10a
• /
• pp.106-110
• /
• 2001

The ball-end milling process is widely used in the die/mold industries, and it is very suitable for the machining of free-form surfaces. However, this process is inherently inefficient process to compared with the end-milling or face milling process, since it relays upon the machining at the cutter/surface contact point. The machined part is the result of continuous point-to-point machining on the free-form surface. And cusps (or scallops) remain at the machined part along the cutter paths and they give the geometrical roughness of the workpiece. Thus, for the good geometrical roughness of the workpiece, it is required very tightly spaced cutter paths in this ball-endmilling process. However, with the tight cutter paths, the geometrical roughness of the workpiece is not regular on the workpiece since the cusp height is variable in the previously developed ISO-parametric or Cartesian machining methods. This paper suggests a method of tool path generation which makes the geometrical roughness of workpiece be constant through the machined surface. In this method, Ferguson Surface design Model is used and cusp height is derived from the instantaneous curvatures. And, to have constant cusp height, an increment of parameter u or v is estimated along the reference cutter path. In ball-end milling experiments, the cusp pattern was examined, and it was proved that the geometrical roughness could be regular by suggested tool path generation method.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.1
• /
• pp.15-21
• /
• 2002

We investigated effects of electrical, physical, and chemical parameters on energy transfer, NO conversion, and light emission in the dielectric barrier discharge (DBD) process. As gap distance between electrodes increased, discharge onset voltage increased. However, as gap distance between electrodes increased, electric field which initiates discharge showed approximately the same value, 30kV/cm. The discharge onset voltage of the coarse surface electrode was lower than that of the smooth surface electrode. And, energy transfer was slightly enhanced in the coarse electrode condition. However, NO conversion rate decreased with the coarse surface electrode because more uniform discharge can be obtained on the smooth surface electrode. The NO conversion rate increased with decreasing the initial concentration, so the DBD process is more feasible in the lower concentration condition. The variation of gas residence time tested at the same energy density in the experiment did not affect on the NO conversion. The result shows that the NO conversion rate mainly depends on the energy density. The DBD process is able to adjust on plasma-photocatalyst process because it emits the short wavelength light in the range of ultraviolet. The intensity of light emission increased with the increase of the energy transfer to the reactor and the gas flow rate.

• Journal of Korean Society for Quality Management
• /
• v.42 no.4
• /
• pp.685-700
• /
• 2014

Purpose: The purpose of this paper is to develop a systematic weighting procedure based on process capability indices method applying weighted mean squared error minimization (WMSE) approach to dual response surface optimization. Methods: The proposed procedure consists of 5 steps. Step 1 is to prepare the alternative vectors. Step 2 is to rank the vectors based on process capability indices in a pairwise manner. Step 3 is to transform the pairwise rankings into the inequalities between the corresponding WMSE values. Step 4 is to obtain the weight value by calculating the inequalities. Or, step 5 is to obtain the weight value by minimizing the total violation amount, in case there is no weight value in step 4. Results: The typical 4 process capability indices, namely, $C_p$, $C_{pk}$, $C_{pm}$, $C_{pmk}$ are utilized for the proposed procedure. Conclusion: The proposed procedure can provide a weight value in WMSE based on the objective quality performance criteria, not on the decision maker's subjective judgments or experiences.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.674-675
• /
• 2016

In this paper, we propose a manufacturing process model of Internet of Things devices using a Printed Circuit Board (PCB)-mounted RFID tag chip for reducing electronic wastes. Electrical and electronic products require a PCB surface mount and many examination. Also, conventional barcode systems cannot provide traceability management in PCB manufacturing before finishing Surface Mount Technology (SMT) process. The proposed process model does not require workers' attaching and detaching process unlike barcode systems. Also, RFID tag chip can record all the data in manufacturing steps. Thus, the number of connections to a database management system (DBMS) can be reduced.

• Korean Journal of Materials Research
• /
• v.29 no.8
• /
• pp.483-490
• /
• 2019

Currently, the Korean nuclear industry uses ZIRLO as material for nuclear fuel cladding(zirconium alloy). KEPCO Nuclear Fuel is in the process of developing a HANA alloy to enable domestic production of cladding. Cladding manufacture involves multistage heat treatments and pickling processes, the latter of which is vital for the removal of defects and impurities on the cladding surface. SMUT that forms on the cladding surface during such pickling process is a source of surface defects during heat treatment and post-treatment processes if not removed. This study analyzes ZIRLO, HANA-4, and HANA-6 alloy claddings to extensively study the SEM/EDS, XRD, and particle size characteristics of SMUT, which are second phase particles that are formed on the cladding surface during pickling processes. Using the analysis results, this study observes SMUT formation characteristics according to Nb concentration in Zr alloys during the washing process following the pickling process. In addition, this study observes SMUT removal characteristics on cladding surfaces according to concentrations of nitric acid and hydrofluoric acid in the acid solution.