• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.5-14
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• 2015

Recently, the use of wood resources has been limited due to global environmental change, like global warming and desertification. It is very critical in Korea's paper industries because lots of virgin pulp are dependant on direct import from abroad for printing grade of paper. In this work, the alternatively best available technique for reducing the import amounts of BKP (bleached Kraft pulp) was considered by mixing DIP (deinked pulp) and TMP (thermomechanical pulp) for the manufacture of high quality paper. Generally known, the sheet prepared from fibrous raw materials of DIP and TMP has lower strength and optical properties than that prepared from BKP. This study was aimed to improve the sheet quality by using DIP and TMP. 4 kinds of polyelectrolytes were approached to find out the best effects on physical strength and optical brightness improvements, and high retention behaviors with GCC (ground calcium carbonate). In conclusion, amphoteric PAM with 1,000,000 molecular weight (g/mol) and 0.5 charge density (meq/g) was best for the improvement of strength properties with the mixture of DIP and TMP. GCC retention rate was also the highest with cationic-PAM of above 2,000,000 molecular weight (g/mol) and about 2.0-3.0 charge density (meq/g) of strengthening agent.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.218-224
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• 2020

PURPOSE. The objectives of this study were to evaluate the fracture strength and fracture patterns of provisional crowns fabricated from different materials and techniques after receiving stress from a simulated oral condition. MATERIALS AND METHODS. A monomethacrylate-based resin (Unifast Trad) and a bis-acryl-based (Protemp 4) resin were used to fabricate provisional crowns using conventional direct technique. A milled monomethacrylate resin (Brylic Solid) and a 3D-printed bis-acrylate resin (Freeprint Temp) were chosen to fabricate provisional crowns using the CAD/CAM process. All cemented provisional crowns (n=10/group) were subjected to thermal cycling (5,000 cycles at 5°-55℃) and cyclic occlusal load (100 N at 4 Hz for 100,000 cycles). Maximum force at fracture was tested using a universal testing machine. RESULTS. Maximum force at fracture (mean ± SD, N) of each group was 657.87 ± 82.84 for Unifast Trad, 1125.94 ± 168.07 for Protemp4, 953.60 ± 58.88 for Brylic Solid, and 1004.19 ± 122.18 for Freeprint Temp. One-way ANOVA with Tamhane post hoc test showed that the fracture strength of Unifast Trad was statistically significantly lower than others (P<.01). No statistically significant difference was noted among other groups. For failure pattern analysis, Unifast Trad and Brylic Solid showed less damage than Protemp 4 and Freeprint Temp groups. CONCLUSION. Provisional crowns fabricated using the CAD/CAM process and the conventionally fabricated bis-acryl resins exhibited significant higher fracture strength compared to conventionally fabricated monomethacrylate resins after the aging regimen. Therefore, CAD/CAM milling and 3D printing of provisional restorations may be good alternatives for long term provisionalization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.10
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• pp.623-629
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• 2014

For the semiconductor device safety from over current in the digital electronic circuit system must be surely designed that it's surface mount type micro fuse device. In this paper, We has analysed to the fusing character of micro fuse as a function changed thickness of thermosetting ink epoxy. To the change of thermosetting ink epoxy thickness with in production lot, in the electrically character (fusing test in the 2 multiple over current and 10 multiple over current, surface temperature test in the 1.25 multiple over current) of micro fuse has been tested. According to the electrically character result, changed thickness of thermosetting ink epoxy in designed micro fuse withheld direct effect in both end resistance changes. Also, because high thermal energy in the micro fuse test of over current was occurred to effect such as thermal runaway and explosion. Therefore, screen printing process in the design of micro fuse using thermosetting ink epoxy is very important for production quality improvement.

• Polymer(Korea)
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• v.28 no.4
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• pp.305-313
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• 2004

A vacuum pressure-difference technique for making a nano-precision replica is investigated for various applications. Master patterns for replication were fabricated using a nano-replication printing (nRP) process. In the nRP process, any picture and pattern can be replicated from a bitmap figure file in the range of several micrometers with resolution of 200nm. A liquid-state monomer is solidified by two-photon absorption (TPA) induced by a femto-second laser according to a voxel matrix scanning. After polymerization, the remaining monomers were removed simply by using ethanol droplets. And then, a gold metal layer of about 30nm thickness was deposited on the fabricated master patterns prior to polydimethylsiloxane molding for preventing bonding between the master and the polydimethylsiloxane mold. A few gold particles attached on the polydimethylsiloxane stamp during detaching process were removed by a gold selecting etchant. After fabricating the polydimethylsiloxane mold, a nano-precision polydimethylsiloxane replica was reproduced. More precise replica was produced by the vacuum pressure-difference technique that is proposed in this paper. Through this study, direct patterning on a glass plate, replicating a polydimethylsiloxane mold, and reproducing polydimethylsiloxane replica are demonstrated with a vacuum pressure-difference technique for various micro/nano-applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.346-351
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• 2018

Metal three-dimensional (3D) printing technologies are mainly classified as powder bed fusion (PBF) and direct energy deposition (DED) methods according to the method of application of a laser beam to metallic powder. The DED method can be used to fabricate fine and hard 3D metallic structures by applying a strong laser beam to a thin layer of metallic powder. The PBF method involves slicing 3D graphics to be a certain height, laminating metal powders, and making a 3D structure using a laser. While the DED method has advantages such as laser cladding and metallic welding, it causes problems with low density when 3D shapes are created. The PBF method was introduced to address the structural density issues in the DED method and makes it easier to produce relatively dense 3D structures. In this paper, thin lines were produced by using PBF 3D printers with stainless-steel powder of roughly $30{\mu}m$ in diameter with a galvano scanner and fiber-transferred Nd:YAG laser beam. Experiments were carried out to find the optimal conditions for the width of a line depending on the processing times, laser power, spot size, and scan speed. The optimal conditions were two scanning processes in one line structure with a laser power of 30 W, spot size of $28.7{\mu}m$, and scan speed of 200 mm/s. With these conditions, a minimum width of about $85.3{\mu}m$ was obtained.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.913-918
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• 2005

It is expected that the inkjet technology offers prospect for reliable and low cost manufacturing of FPD (Flat Panel Display). This inkjet technology also offers a more simplified manufacturing process for various part of the FPD than conventional process. For example, recently the novel manufacturing processes of color filter (C/F) in LCD, or RGB patterning in OLED by inkjet printing method have been developed. This elaborates will be considered as the precious point of manufacturing process for the mass production of enlarged-display panel with a low price. On this point of view, we would like to review the status of inkjet technology in FPD, with some results on forming micro line by inkjet patterning of suspension type silver nano ink as below. We have studied the inkjet patterning of synthesized aqueous silver nano-sol on interface-controlled ITO glass substrate. Furthermore, we designed the conductive ink for direct inkjet patterning on bare ITO glass substrate. The first, the highly concentrated polymeric dispersant-assisted silver nano sol was prepared. The high concentration of batch-synthesized silver nano sol was possible to 40 wt%. At the same time the particle size of silver nanoparticles was below $10{\sim}20nm$. The second, the synthesized silver nano sol was inkjet - patterned on ITO glass substrate. The connectivity and width of fine line depended largely on the wettability of silver nano sol on ITO glass substrate, which was controlled by surfactant. The relationship was understood by wetting angle. The line of silver electrode as fine as $50{\sim}100\;{\mu}m$ was successfully formed on ITO glass substrate. The last, the direct inkjet-patternable silver nano sol on bare ITO glass substrate was designed also.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.16-21
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• 2008

The key component of a direct methanol fuel cell (DMFC) is the membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane and catalyst layers (anode and cathode electrode). Generally the catalyst layer is coated on the porous electrode supporter (e.g. carbon paper or cloth) using various coating methods such as brushing, decal transfer, spray coating and screen printing methods. However, these methods were disadvantageous in terms of the uniformity of catalyst layer thickness, catalyst loss, and coating time. In this work, we used bar-coating method which can prepare the catalyst layer with uniform thickness for MEA of DMFC. The surface and cross-section morphologies of the catalyst layers were observed by SEM. The performances and resistance of the MEAs were investigated through a single cell evaluation and impedance analyzer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.176-176
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• 2007

Flat-panel direct conversion detectors used in compound substance of semiconductor are being studied for digital x-ray imaging. Recently, such detectors are deposited by physical vapor deposition(PVD) generally. But, most of materials (HgI2, PbI2, TlBr, PbO) deposited by PVD have shown difficult fabrication and instability for large area x-ray imaging. Consequently, in this paper, we propose applicable potentialities for screen printing method that is coated on a substrate easily. It is compared to electrical properties among semiconductors such as $HgI_2$, $PbI_2$, PbO, HgBrI, InI, and $TlPbI_3$ under investigation for direct conversion detectors. Each film detector consists of an ~25 to $35\;{\mu}m$ thick layer of semiconductor and was coated onto the substrate. Substrates of $2cm{\times}2cm$ have been used to evaluate performance of semiconductor radiation detectors. Dark current, sensitivity and physics properties were measured. Leakage current of $HgI_2$ as low as $9pA/mm^2$ at the operation bias voltage of ${\sim}1V/{\mu}m$ was observed. Such a value is not better than PVD process, but it is easy to be fabricated in high quality for large area x-ray Imaging. Our future efforts will concentrate on optimization of growth of film thickness that is coated onto a-Si TFT array.

• Journal of Conservation Science
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• v.34 no.6
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• pp.471-479
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• 2018

Seonunsa Temple is a site of Dancheong cultural significance in Daewoongjeon. Three-dimensional (3D) scanning can be used to create a simulation in 1:1 ratio without touching the Dancheong patterns directly. The traditional method of recreating Dancheong was paining with tracing paper using a fix pin. However, manual direct copy processes can cause and damage to the objects. This study shows the results of a simulation of a tranditional Dancheong patterns as an alternative; the simulation was able to reduce dimensional errors and prevent damage by using 3D scanning. As a result, objective and precise proportions of the simulation were acquired. The 3D scanning method may be applied for work such as the replication and restoration of the drawing, 3D fabrication of the original data, and printing of the additional drawing. In addition, with the production of 3D materials, a virtual museum is possible.

• Journal of the Korea Fashion and Costume Design Association
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• v.8 no.3
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• pp.35-47
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• 2006

This study aims to suggest the Deconstruction theory that is changing and developing by being converted into visual from as cultural code which reflects the spirit of the times and art style as well as to analyze the phenomenon of deconstruction expressed in the Fashion photographs. Fashion photographs are historical documents presenting us with the evidence of the ideal body types and culture throughout time. Fashion photographs is direct information about the fashion itself, and at the same time, it transmits various circumstances of the times. Fashion photographs has opened a new aspect called visual communication, when it's seen in new, more profound way, instead of being locked in its visible frame. Photograph is no longer a mere means to preserve documentation or pursue artistic expression. Instead, it's now regarded as a way to pursue visual transmission owing to its cognitive psychology, and this is a remarkable step toward new thing. In this study, the possible visual information function of photograph was explored from diverse aspects, such as the combination of photo and design, its linking to printing technology's mass production function, or the development of its imagery symbolism. This study shows that the nature of deconstruction can be explained as deconstruction of the sexes, deconstruction of the time and space, and deconstruction of the genre.