• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.110-112
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• 2006

Membrane electrode assembly (MEA) for polymer electrolyte fuel cell (PEFC) are commonly prepared in the research laboratory by spraying, screen-printing and brushing catalyst slurry onto membrane or other support material like carbon paper or polyimide film in a batch style. These hand applications of the catalyst slurry are painstaking process with respect to precision of catalyst loading and reproducibility. It has been generally mentioned that the adoption of continuous process is very helpful to develop the reliable product. In the present work, we report the results of using continuous type coater with doctor-blade to coat catalyst slurry for preparing the MEA catalyst layers In a faster and highly reproducible fashion. We show that while expectedly faster than batch style, the machine coater requires the use of slurry of appropriate composition and a properly selected transfer decal material in order to achieve superior MEA plat lnw loading reproducibility. To make highly viscous catalyst slurry that is imperative for using coater, we use 40wt.% Nafion solution and minimize the content of organic solvent. And the choice of proper high surface area catalyst is important in the viewpoint of making well-dispersed slurry. After catalyst coating onto the support material, we transferred the catalyst layer to both sides of Nafion membrane by hot-pressing In this case, the degree of transfer was Influenced by hot-pressing condition including temperature, pressure, and time. To compare the transferring ability, we compared so many films and detaching papers. And among the support, polyethylene terephthalate(PET) film shows the prominent result.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.276-279
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• 2004

Plasma enhanced chemical vapor deposition (PECVD) of silicon nitride (SiN) is a proven technique for obtaining layers that meet the needs of surface passivation and anti-reflection coating. In addition, the deposition process appears to provoke bulk passivation as well due to diffusion of atomic hydrogen. This bulk passivation is an important advantage of PECVD deposition when compared to the conventional CVD techniques. A further advantage of PECVD is that the process takes place at a relatively low temperature of 300t, keeping the total thermal budget of the cell processing to a minimum. In this work SiN deposition was performed using a horizontal PECVD reactor system consisting of a long horizontal quartz tube that was radiantly heated. Special and long rectangular graphite plates served as both the electrodes to establish the plasma and holders of the wafers. The electrode configuration was designed to provide a uniform plasma environment for each wafer and to ensure the film uniformity. These horizontally oriented graphite electrodes were stacked parallel to one another, side by side, with alternating plates serving as power and ground electrodes for the RF power supply. The plasma was formed in the space between each pair of plates. Also this paper deals with the fabrication of multicrystalline silicon solar cells with PECVD SiN layers combined with high-throughput screen printing and RTP firing. Using this sequence we were able to obtain solar cells with an efficiency of 14% for polished multi crystalline Si wafers of size 125 m square.

• Journal of Korean Library and Information Science Society
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• v.50 no.3
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• pp.1-22
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• 2019

Western society has depreciated the Middle Ages as the 'Darkness'. However, if Islam, which led the medieval millennium, had not spread paper and art of papermaking, and Arabic translations to the Western countries, translating and interpreting Arabic manuscripts into Greek and Latin, Gutenberg's printing press, Reformation, and Renaissance could not take place. They were not destructors of ancient knowledge and civilization, but were the protagonists of restoration and resurrection. The base camp is the Mosque and Islamic library(the House of Wisdom), which was referred to as a Muslim community. This study traced Islamic libraries that emerged in the process of establishing the Islamic dynasties and controlling Arabian Peninsula, Africa, Iberian Peninsula. For this purpose, the Islamic library was divided into the caliph library led by the royal families, the public library attached to the mosques, and the private library established by the viziers and scholars, etc. Then, the researcher analyzed history and development, roles and functions, impact and Importance on human civilization, and stagnation and decline, focusing on major libraries that existed in the Islamic cities of Damascus, Mecca, Baghdad, Aleppo, Cordoba, Cairo, Fes, Tunis, etc.

• Advances in aircraft and spacecraft science
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• v.4 no.3
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• pp.281-296
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• 2017

The axial-injection end-burning hybrid rocket proposed twenty years ago by the authors recently recaptured the attention of researchers for its virtues such as no ${\zeta}$ (oxidizer to fuel mass ratio) shift during firing and good throttling characteristics. This paper is the first report verifying these virtues using a laboratory scale motor. There are several requirements for realizing this type of hybrid rocket: 1) high fuel filling rate for obtaining an optimal ${\zeta}$; 2) small port intervals for increasing port merging rate; 3) ports arrayed across the entire fuel section. Because these requirements could not be satisfied by common manufacturing methods, no previous researchers have conducted experiments with this kind of hybrid rocket. Recent advances in high accuracy 3D printing now allow for fuel to be produced that meets these three requirements. The fuel grains used in this study were produced by a high precision light polymerized 3D printer. Each grain consisted of an array of 0.3 mm diameter ports for a fuel filling rate of 98% .The authors conducted several firing tests with various oxidizer mass flow rates and chamber pressures, and analysed the results, including ${\zeta}$ history, using a new reconstruction technique. The results show that ${\zeta}$ remains almost constant throughout tests of varying oxidizer mass flow rates, and that regression rate in the axial direction is a nearly linear function of chamber pressure with a pressure exponent of 0.996.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.941-946
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• 2021

This paper is a study on the design and implementation of a rehabilitation wearable robotic hand that reduces weight and volume by using a 3D printer and a motor. Rehabilitation wearable robots are important not only for the effect of rehabilitation but also for ease of use. However, most of the currently researched and developed rehabilitation exoskeleton robots are heavy in volume and weight, or they have to be used in place. Therefore, a wearable robot that is easy to wear and does not burden the user is required, so a lightweight electric rehabilitation wearable robot hand is proposed. A 3D printer was used to reduce the weight and volume and to make it easier to wear. In addition, to increase portability, the structure was simplified by adopting an electric method rather than a pneumatic method. Finally, the effectiveness was examined through the experiment of the lightweight electric rehabilitation wearable robot hand.

• The Korean Journal of Archival Studies
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• no.2
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• pp.129-168
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• 2000

$Chos{\check{o}}n$ Dynasty was governed by the words of king, however, if they were not announced by the form of public document, they were useless. Therefore, the form of public document was the symbol of governing activity, and it was very important to manage the public record in operating the nation affairs. However, the point we should consider is that $Chos{\check{o}}n$ Dynasty, in the case of managing the public record, edited 'the original' instead of preserving them. And so, the preservation of the public record was deeply related to the editing of history. In Late Korea dynasty, the management of the public record got into utter confusion and so many troubles were occurred. In order to resolve these problems, the movements which innovated the public record managements system was gradually extended. This movements were continued in $Chos{\check{o}}n$ Dynasty. Finally, through the several modification procedures, the rules of public record management were legislated by 'Kyong Kuk Dae Jeon'(經國大典). Especially, by laws of 'Kyong Kuk Dae Jeon', not only the daily records of Secretary Department(承政院) but also the important documents which was related to the government branch should be booked in the last decade of the year and the number of the books had to be reported to the king. This rule made certification of the fact that the king was the last confirmer of the public record management. In addition, through the procedure of printing the record of the national affairs, and the diplomatic once in three years, and then preserving that public record in the National Department(議政府), other departments responsible and the archives, the National Department practically took part in the public record management. The management system was also changed in order that the public record was virtually used and consulted before taking the procedure of immortal preservation. All public documents were classified by the definite rule and filed in a same volume. After classifying and filing, certainly, for making convenience of reference and application of public record, records were indicated by the paper card. It may be that, after the step of reference, application and indicating, the public documents were gradually transferred to the next step. In these procedures, Early $Chos{\check{o}}n$ public documents system was confirmed.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.142-144
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• 2016

Recent promising technologies of the manufacturing sector interest, and the interest in 3D printing that is expected to cause a huge ripple effect rapidly, and various types of products advertised in accordance with the falling price of 3D printers is spreading. However, the personal 3D printers that are currently being advertised is used for Injection output of the simple type that does not require a high processing precision in accordance with the limitation of technical performance, and consumer satisfaction is very low. In this paper, we propose a 3D printer, 3D precision to overcome existing limitations in the way the printer's high SLA 3D printer that combines injection method and the LSU (Laser Scanning Unit) in the office laser printer polygon mirror scanning method. 3D printers which are proposed to improve the accuracy and manufacturing speed is expected to replace the existing entry-level 3D printer.

• International Journal of Advanced Culture Technology
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• v.7 no.1
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• pp.243-247
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• 2019

The most commonly used 3D modeling file formats are OBJ (Wavefront file format specification) and STL (STereoLithography). Although they have a common point of view in 3D on the screen, detailed functions are different according to purpose of development. OBJ is the most commonly used 3D file format and STL is mainly used as 3D file format for 3D printing. However, in the field of Scientific Visualization, precise analysis is required. There is a difference in accuracy depending on the type of 3D file format. OBJ and STL are not suitable for delicate surface description because they form meshes in the form of triangular polygons. And if you increase the number of triangle polygons, it will be smoother, but the file size also increases exponentially and causes excessive CPU usage. In contrast, VTK provides a variety of polygon structures, including triangular polygons as well as rectangular polygons and cube polygons. Thus, delicate surface depiction is possible. Delicate surface rendering is possible and file size is not large. This paper describes the concept and structure of VTK. We also compared the load times and file sizes between VTK, STL, and OBJ in the Chrome browser. In addition, the difference in surface rendering ability between VTK, STL, and OBJ is intuitively viewed based on the screen in which each 3D file format is implemented under the same conditions. This study is expected to be helpful for efficient 3D file format for precise implementation of Web - based Scientific Visualization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.58-62
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• 2019

The printing environment for output is commonly referred to as computers and printers using local connections in 1: 1 format. However, the local connection environment has spatial, temporal, and financial physical limitations. Therefore, a network-based output environment has been proposed and utilized as a way to supplement this.A network printer receives data in packets for document output, and generally does not support a security protocol. Therefore, when a network printer is used, there is a possibility that the content of a document being printed is stolen by being exposed to a network attack such as a meson attack or spoofing against a printed matter. In this paper, we define and define the requirements to cope with the meson attack on printed materials in a network printer environment where security protocol is not supported.