• Title/Summary/Keyword: Direct writing Process

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Droplet Ejection and Experimental Study on the Application of Industrial Inkjet Printhead (산업용 잉크젯 프린트헤드 액적 토출현상의 실험적 해석)

  • Park, Sung-Jun
    • Journal of Institute of Convergence Technology
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    • v.1 no.1
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    • pp.34-40
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    • 2011
  • In this paper, a hybrid design tool combining one-dimensional(1D) lumped model and three-dimensional computational fluid dynamics(CFD) approach has been developed in order to evaluate the performance of inkjet print head and droplet control process are studied to reduce the deviations between nozzles which affect the size of the printed line for the industrial application of direct writing on printed circuit boards(PCB). 1D lumped model analysis shows that it is useful tool for evaluating performance of an inkjet head by varying the design parameters. The differences in ejected volume and droplet velocity between analytical and experimental result are within 12%. Time sequence of droplet generation is verified by the comparison between 3D analysis result and photographic images acquired by stroboscopic technique. In addition, by applying DPN process, velocity and volume uniformity between nozzles is dramatically improved that the tolerance achieved by the piezoelectric inkjet printhead across the 64 nozzles is 5 to 8%. A printed line pattern is successfully obtained using the fabricated inkjet print head and droplet calibration system.

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Development of Real-time Process Management System for improving safety of Shop Floor (생산현장의 안전성 향상을 위한 실시간 공정관리 시스템 개발)

  • Lee, Seung Woo;Nam, So Jeong;Lee, Jai Kyung;Lee, Hwa Ki
    • Journal of the Korea Safety Management & Science
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    • v.15 no.4
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    • pp.171-178
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    • 2013
  • Workers are avoiding production/manufacturing sites due to the poor working environment and concern over safety. Small and medium-sized businesses introduce new equipment to secure safety in the production site or ensure effective process management by introducing the real-time monitoring technique for existing equipment. The importance of real-time monitoring of equipment and process in the production site can also be found in the ANSI/ISA-195 model. Note, however, that most production sites still use paper-based work slip as a process management technique. Data reliability may deteriorate because information on the present condition of the production site cannot be collected/analyzed properly due to manual data writing by the worker. This paper introduces the monitoring and process management technique based on a direct facility interface to secure safety in the field by improving the poor working environment and enhance there liability and real-time characteristics of the production data. Since the data is collected from equipment in real-time directly through the SIB-based interface and PLC-based interface, problems associated with workers' manual data input are expected to be solved; safety can also be improved by enhancing workers' attention to work by minimizing workers' injuries and disruption.

Fabricating a Micro-Lens Array Using a Laser-Induced 3D Nanopattern Followed by Wet Etching and CO2 Laser Polishing

  • Seung-Sik Ham;Chang-Hwam Kim;Soo-Ho Choi;Jong-Hoon Lee;Ho Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.4_1
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    • pp.517-527
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    • 2023
  • Many techniques have been proposed and investigated for microlens array manufacturing in three-dimensional (3D) structures. We present fabricating a microlens array using selective laser etching and a CO2 laser. The femtosecond laser was employed to produce multiple micro-cracks that comprise the predesigned 3D structure. Subsequently, the wet etching process with a KOH solution was used to produce the primary microlens array structures. To polish the nonoptical surface to the optical surface, we performed reflow postprocessing using a CO2 laser. We confirmed that the micro lens array can be manufactured in three primary shapes (cone, pyramid and hemisphere). Compared to our previous study, the processing time required for laser processing was reduced from approximately 1 hour to less than 30 seconds using the proposed processing method. Therefore, micro lens arrays can be manufactured using our processing method and can be applied to mass productionon large surface areas.

Enhancing Electrical Properties of N-type Bismuth Telluride Alloys through Graphene Oxide Incorporation in Extrusion 3D Printing

  • Jinhee Bae;Seungki Jo ;Kyung Tae Kim
    • Journal of Powder Materials
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    • v.30 no.4
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    • pp.318-323
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    • 2023
  • The thermoelectric effect, which converts waste heat into electricity, holds promise as a renewable energy technology. Recently, bismuth telluride (Bi2Te3)-based alloys are being recognized as important materials for practical applications in the temperature range from room temperature to 500 K. However, conventional sintering processes impose limitations on shape-changeable and tailorable Bi2Te3 materials. To overcome these issues, three-dimensional (3D) printing (additive manufacturing) is being adopted. Although some research results have been reported, relatively few studies on 3D printed thermoelectric materials are being carried out. In this study, we utilize extrusion 3D printing to manufacture n-type Bi1.7Sb0.3Te3 (N-BST). The ink is produced without using organic binders, which could negatively influence its thermoelectric properties. Furthermore, we introduce graphene oxide (GO) at the crystal interface to enhance the electrical properties. The formed N-BST composites exhibit significantly improved electrical conductivity and a higher Seebeck coefficient as the GO content increases. Therefore, we propose that the combination of the extrusion 3D printing process (Direct Ink Writing, DIW) and the incorporation of GO into N-BST offers a convenient and effective approach for achieving higher thermoelectric efficiency.

The study of optimal reduced-graphene oxide line patterning by using femtosecond laser pulse (펨토초 레이저 펄스를 이용한 환원된 그래핀의 최소 선폭 패턴 구현에 관한 연구)

  • Jeong, Tae-In;Kim, Seung-Chul
    • Journal of the Korea Convergence Society
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    • v.11 no.7
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    • pp.157-162
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    • 2020
  • In recent years, laser induced graphene process have been intensively studied for eco-friendly electronic device such as flexible electronics or thin film based energy storage devices because of its simple and effective process. In order to increase the performance and efficiency of an electronic device using such a graphene patterned structure, it is essential to study an optimized laser patterning condition as small as possible linewidth while maintaining the graphene-specific 2-dimensional characteristics. In this study, we analyzed to find the optimal line pattern by using a Ti:sapphire femtosecond laser based photo-thermal reduction process. we tuned intensity and scanning speed of laser spot for generating effective graphene characteristic and minimum thermal effect. As a result, we demonstrated the reduced graphene pattern of 30㎛ in linewidth by using a focused laser beam of 18㎛ in diameter.

Polymer Inkjet Printing: Construction of Three-Dimensional Structures at Micro-Scale by Repeated Lamination

  • Yun, Yeon-Hee;Kim, Jae-Dong;Lee, Byung-Kook;Cho, Yong-Woo;Lee, Hee-Young
    • Macromolecular Research
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    • v.17 no.3
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    • pp.197-202
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    • 2009
  • Solution-based, direct-write patterning by an automated, computer-controlled, inkjet technique is of particular interest in a wide variety of industrial fields. We report the construction of three-dimensional (3D), micro-patterned structures by polymer inkjet printing. A piezoelectric, drop-on-demand (DOD) inkjet printing system and a common polymer, PVA (poly(vinyl alcohol)), were explored for 3D construction. After a systematic preliminary study with different solvent systems, a mixture of water and DMSO was chosen as an appropriate solvent for PVA inks. The use of water as a single solvent resulted in frequent PVA clogging when the nozzles were undisturbed. Among the tested polymer ink compositions, the PVA inks in a water/DMSO mixture (4/1 v/v) with concentrations of 3 to 5 g/dL proved to be appropriate for piezoelectric DOD inkjet printing because they were well within the proper viscosity and surface tension range. When a dot was printed, the so-called 'coffee-ring effect' was significant, but its appearance was not prominent in line printing. The optimal polymer inkjet printing process was repeated slice after slice up to 200 times, which produced a well-defined, 3 D micro-patterned surface. The overall results implied that piezoelectric DOD polymer inkjet printing could be a powerful, solid-freeform, fabrication technology to create a controlled 3D architecture.

Improvement of Conductive Micro-pattern Fabrication using a LIFT Process (레이저 직접묘화법을 이용한 미세패턴 전도성 향상에 관한 연구)

  • Lee, Bong-Gu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.5
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    • pp.475-480
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    • 2017
  • In this paper, the conductivity of the fine pattern is improved in the insulating substrate by laser-induced forward transfer (LIFT) process. The high laser beam energy generated in conventional laser induced deposition processes induces problems such as low deposition density and oxidation of micro-patterns. These problems were improved by using a polymer coating layer for improved deposition accuracy and conductivity. Chromium and copper were used to deposit micro-patterns on silicon wafers. A multi-pulse laser beam was irradiated on a metal thin film to form a seed layer on an insulating substrate(SiO2) and electroless plating was applied on the seed layer to form a micro-pattern and structure. Irradiating the laser beam with multiple scanning method revealed that the energy of the laser beam improved the deposition density and the surface quality of the deposition layer and that the electric conductivity can be used as the microelectrode pattern. Measuring the resistivity after depositing the microelectrode by using the laser direct drawing method and electroless plating indicated that the resistivity of the microelectrode pattern was $6.4{\Omega}$, the resistance after plating was $2.6{\Omega}$, and the surface texture of the microelectrode pattern was uniformly deposited. Because the surface texture was uniform and densely deposited, the electrical conductivity was improved about three fold.

A Comparative Study of the Nurse Licensure Exam Systems between the United States and South Korea (미국과 한국의 간호사 국가면허시험 문항개발과정 비교)

  • Kwak, Chanyeong;Yun, Soon-Nyoung;Kim, Shin-Jeong
    • Korean Journal of Adult Nursing
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    • v.25 no.6
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    • pp.622-632
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    • 2013
  • Purpose: This study was conducted to compare the nurse licensure examination system in Korea with that of the United States (US). Methods: Focus interviews with the administrative staff of the National Council of State Boards of Nursing (NCSBN) were held. two areas were explored in the interviews: the item development process and the general administrative operating procedures. Results: NCLEX-RN items are designed for entry-level practice. The items are subjected to a series of 12 steps including a item writing panel, a content and editorial review, a sensitivity panel, a pre-test, a Differential item functioning panel and a committee review. NCSBN is responsible for the test for registered nurses and one for practical nurses. In contrast the Korean National Health Personnel Licensing Board (KNHPLB) is responsible for nursing is and 21 other health related licensure. Another difference is that in Korea there is no consistent and specialized staff to develop question items. Items are developed by educators who are not active nurses (this last statemtne is not a finding but a point of view usually not given in findings.). Conclusion: Korean nurses form the largest group of health related job categories and the most direct to health care consumers. Therefore, the nursing licensure exam should be acknowledged as the most influential licensure exam in health care services. We recommend a nursing specialized licensing institution to be established with active nurse' participation in item development process to reflect clinical practice into licensure exam.

Laser-induced chemical vapor deposition of micro patterns for TFT-LCD circuit repair (레이저 국소증착을 이용한 TFT-LCD 회로수정 패턴제조)

  • Park Jong-Bok;Jeong Sungho;Kim Chang-Jae;Park Sang-Hyuck;Shin Pyung-Eun;Kang Hyoung-Shik
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.657-662
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    • 2005
  • In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

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Laser-induced chemical vapor deposition of tungsten micro patterns for TFT-LCD circuit repair (레이저 국소증착을 이용한 TFT-LCD회로 수정5 미세 텅스텐 패턴 제조)

  • Park Jong-Bok;Kim Chang-Jae;Park Sang-Hyuck;Shin Pyung-Eun;Kang Hyoung-Shik;Jeong Sung-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.8 s.173
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    • pp.165-173
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    • 2005
  • This paper presents the results for deposition of micrometer-scale metal lines on glass for the development of TFT-LCD circuit repair-system. Although there had been a few studies in the late 1980's for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and W(CO)s was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 m depending on laser power and scan speed while the width was controlled between 50um using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below $1{\Omega}{\cdotu}um$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.