• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.28-35
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• 2023

Moiré patterns emerge due to the interference between the non-emission area of the LED screen and the grid line in an image sensor of a video recording device when taking a video in the presence of the LED screen. To reduce the moiré intensity, we have fabricated an anti-moiré filter using hollow glass microspheres (HGMs) by slot-die coating. The LED screen has a large non-emission area because of a large pitch (distance between LED chips), causing more severe moiré phenomenon, compared with a display panel having a very narrow black matrix (BM). It is shown that HGMs diffuse light in such a way that the periodicity of the screen is broken and thus the moiré intensity weakens. To quantitatively analyze its moiré suppression capability, we have calculated the spatial frequencies of the moiré fringes using fast Fourier transform. It is addressed that the moiré phenomenon is suppressed and thus the amplitude of each discrete spatial frequency term is reduced as the HGM concentration is increased. Using the filter with the HGM concentration of 9 wt%, the moiré fringes appeared depending sensitively on the distance between the LED screen and the camera are almost completely removed and the visibility of a nature image is enhanced at a sacrifice of luminance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.36-42
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• 2024

Roll-to-roll processing holds an integral position within the manufacturing landscape, and its significance reverberates across numerous industries. This versatile technology platform encompasses a diverse array of process methods and accommodates a wide spectrum of material categories, making it a cornerstone of modern production. Within this expansive domain, two commonly employed coating techniques, namely the slot die and gravure coating methods, have earned their prominence for their precision and efficiency in delivering flawless coatings. Additionally, the realm of drying processes relies heavily on thermal drying, infrared (IR) drying, and ultraviolet (UV) drying methods to expedite the transformation of materials from their liquid or semi-liquid states to solid, ready-to-use products. The undeniable importance of roll-to-roll processing lies in its ability to streamline manufacturing processes, reduce costs, and enhance product quality. This article embarks on a comprehensive journey to fathom the depth of this importance by delving into the intricacies of these common roll-to-roll process methods. Through rigorous research and meticulous data collection, we aim to shed light on the pivotal role these techniques play in shaping various industries and advancing the world of manufacturing. By understanding their significance, we can harness the full potential of roll-to-roll processing and pave the way for innovation and excellence in production.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.178-182
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• 2006

Five model coils of 6.6 kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals. The voltage applied to the coils was 3.81 kV, 4.76 kV, 6.0 kV and 6.6 kV, respectively. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector(PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns are consistent with the result of measurement using PDD and TGA instruments. AC breakdown test was performed on five model coils in order to confirm the result of PD measurements. All the failures were located in a line-end coil at the exit from the core slot.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.685-688
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• 2008

Planar antennas are very efficient for the use of the out-door data transmission applications due to their low-profile characteristics. But the size of the antenna in UHF band blocks the practical usage. In this paper, a miniaturized planar antenna is investigated for the application of AMR system in UHF band. The designed antenna is fabricated in the form of the microstrip patch on the FR-4 substrate. The miniaturization is achieved by slot-loading on the patch. First, effects of simple slots on the size reduction are analyzed, followed by the design using more complex slots resulting in the reduction ratio of 37.9% in 425.6 MHz and bandwidth of 3.8 MHz. The effect of epoxy coating for the protection is also investigated.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.92-96
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• 2019

In the presence of ${\mu}-tip$ embedded in a slot-die head for stripe coatings, there arises the capillary flow that limits an increase of the stripe density, which is required for the potential applications in organic light-emitting diode displays. With an attempt to suppress it, we have employed a computational fluid dynamics software and performed simulations by varying the ${\mu}-tip$ length and the contact angles of the head lip and ${\mu}-tip$. We have first demonstrated that such a capillary flow phenomenon (a spread of solution along the head lip) observed experimentally can be reproduced by the computational fluid dynamics software. Through simulations, we have found that stronger capillary flow is observed in the hydrophilic head lip with a smaller contact angle and it is suppressed effectively as the contact angle increases. When the contact angle of the head lip increases from $16^{\circ}$ to $130^{\circ}$, the distance a solution can reach decreases sharply from $256{\mu}m$ to $44{\mu}m$. With increasing contact angle of the ${\mu}-tip$, however, the solution flow along the ${\mu}-tip$ is disturbed and thus the capillary flow phenomenon becomes more severe. If the ${\mu}-tip$ is long, the capillary flow also appears strong due to an increase of flow resistance (electronic-hydraulic analogy). It can be suppressed by reducing the ${\mu}-tip$ length, but not as effectively as reducing the contact angle of the head lip.

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.362-367
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• 2007

Stent is a tiny structure made with either ceramic coating and/or bare metal. Being approximately $1{\sim}2 mm$ in diameter, it consists of holes, slots, or void space and is designed to cover entire medical lesions. Stent implantation into patients' arteries has been practiced for a little more than a decade in order to widen the blocked artery. The adoption of the stent has significantly improved the efficacy when compared with the previous medical practice by balloon angioplasty alone. Yet better biomedical performance of the stent is being demanded in order to eliminate the still existing problem of artery restenosis, which means the artery becomes narrowed again. Recent literature survey shows researches on ceramic coatings onto the stent surface, or material design to improve the mechanical response of the stent. This study focuses more on the material design and mechanical analysis. The results showed that the void configuration within the stent affects the mechanical response significantly. The rectangular shape was found to yield expansion at a relatively lower pressure than the elliptical slot for a slotted tube stent. The present results, when combined with research on coating at the stent surface, may provide stents with improved bio-medical performance.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2091-2093
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• 2005

Five model coils of 6.6kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals, respectively The voltage applied to the coils was 3.81kV, 4.76kV, 6.0kV and 6.6kV. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector (PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns coincide with both PDD and TGA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.14-20
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• 2018

Electric vehicles are environmentally friendly because they emit no exhaust gas, unlike gasoline automobiles. However, since they are driven by the electric power from batteries, the distance they can travel based on a single charge depends on their energy density. Therefore, the lithium-ion battery having a high energy density is a good candidate for the batteries of electric vehicles. Since the electrode is an essential component that governs their efficiency, the electrode manufacturing process plays a vital role in the entire production process of lithium-ion batteries. In particular, the coating process is a critical step in the manufacturing of the electrode, which has a significant influence on its performance. In this paper, we propose an innovative process for improving the efficiency and productivity of the coating process in electrode manufacturing and describe the equipment design method and development results. Specifically, we propose a design procedure and development method in order to improve the core plate coating quality by 25%, using a technology capable of reducing the assembly margin due to its high output/high capacity and improving the product capacity quality and assembly process yield. Using this method, the battery life of the lithium-ion battery cell was improved. Compared with the existing coating process, the target loading level is maintained and dispersed to maintain the anode capacity (${\pm}0.4{\rightarrow}{\pm}0.3mg/cm^2r$ reduction).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.979-983
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• 2008

Planar antennas are very efficient for the use of the out-door data transmission applications due to their low-profile characteristics. But the size of the antenna in UHF band blocks the practical usage. In this paper, a miniaturized planar antenna is investigated for the application of AMR system in UHF band. The designed antenna is fabricated in the form of the microstrip patch on the FR-4 substrate. The miniaturization is achieved by slot-loading on the patch. First, effects of simple slots on the size reduction are analyzed, followed by the design using more complex slots resulting in the reduction ratio of 37.9% in 425.6 MHz and bandwidth of 3.8 MHz. The effort of epoxy coating for the protection is also investigated.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.79-84
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• 2020

Unlike a printing process, it is difficult to pattern organic thin films in the longitudinal (coating) direction using a coating process. In this paper, we have investigated the feasibility of patterning organic thin films using needles. To this end, we have slot-coated an aqueous poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) solution in the form of a fine stripe or large area and then applied the dual needle; one for discharging the main solvent of the underlying thin film and the other for sucking the dissolved thin film. We have found that the pattern width and depth increase as the moving speed of the plate decreases. However, it is observed that the sidewall slope is very gentle (the length of the slope is of the order of 200 ㎛) due to the fact that the discharged main solvent is widely spread and then isotropic etching occurs. With this scheme, we have also demonstrated that a fine stripe can be obtained by scanning the dual needle closely. To demonstrate its applicability to solution-processable organic light-emitting diodes (OLEDs), we have also fabricated OLED with the patterned PEDOT:PSS stripe and observed the insulation property in the strong light-emitting stripe.