• Tribology and Lubricants
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• v.36 no.5
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• pp.267-273
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• 2020

This study experimentally investigates hydrophobic surfaces fabricated via additive manufacturing. Additive manufacturing, commonly known as 3D printing, is the process of joining materials to fabricate parts from 3D model data, usually in a layer-upon-layer manner. Digital light processing is used to fabricate hydrophobic surfaces in this study. This method uses photo-curable resins and ultraviolet (UV) sources. Moreover, this technique generally has faster shaping speeds and is advantageous for the fabrication of small components because it enables the fabrication of one layer at a time. Two photo-curable resins with different compositions are used to fabricate micro-patterns of hydrophobic surfaces. The resins are composed of a photo-initiator, monomer, and oligomer. Experiments are conducted to determine suitable process conditions for the fabrication of hydrophobic surfaces depending on the type of resin. The most important factors affecting the process conditions are the UV exposure time and slice thickness. The fabrication capability according to the process conditions is evaluated using the side and top views of the micro-patterns observed using a microscope. The micro-patterns are collapsed and intertwined when the exposure time is short because sufficient light (heat) is not applied to cure the photo-curable resin with a given slice thickness. On the other hand, the micro-patterns are attached to each other when the exposure time is prolonged because the over-curing time can cure the periphery of a given shape. When the slice is thicker, the additional curing area is enlarged in each slice owing to the straightness of UV light, and the slice surface becomes rough.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.4
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• pp.235-251
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• 2011

The aim of this article is to outline the history and importance of the Korean rare books in Coll$\grave{e}$ge de France. With this purpose in mind, the historical background and the process of how these books came to Coll$\grave{e}$ge de France were studied through cataloguing the list, and then analyzing them by subject, printing type, and timeline. We examined the relationship between the private collections of Maurice Courant(1865-1935) and the Korean rare books held in Coll$\grave{e}$ge de France. The Bibliographie Cor$\acute{e}$enne written by Maurice Courant is the most important reference book for studying the publication of the late Joseon dynasty and finding the whereabouts of the Korean books in France. Also, we tried to figure out the best way to implement and make use of a bibliographic database, and contribute to the exploration and study of Korean Cultural Heritage scattered outside Korea.

• Journal of the Korean Home Economics Association
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• v.45 no.2
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• pp.91-103
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• 2007

The purpose of this study is to investigate the types and functions of brand labels on clothing. We surveyed the materials and manufacturing methods for brand labels by visiting the label stores and label manufacturers. 200 pieces of children's wear were surveyed. The label attributes that were studied were: the number of labels, the location of the labels, the attachment system for the labels, the color of the labels, the materials used to make the labels, manufacturing methods, and the size of the labels. From this investigation a brand label was classified into a main label and a point label. The main results were: 1. Materials such as fabrics, nonwovens, leather, suede, rubber, PVC, silicone, and metals are used for brand labels. The manufacturing methods for brand labels are weaving, printing, high frequency, heating, and molding. 2. More than 54% of clothes have more than two brand labels attached. This percentage exceeds the attaching of only one brand label in rate. An inside brand label is located at a certain place. This inside label uses only fabric material reflecting inherent brand color and design. The outside brand label is located at several places with consideration of the clothes design. This label uses various materials, colors, and characters matching with the clothes. As for the size, an inside label is mainly medium in size, whereas an outside label is small. 3. A brand label is classified into a main label (first label) and a point label (second label), which are defined as follows. A main label indicates the brand name and is located inside at a certain place using an inherent brand design and a fabric material. A point label is an additional label to express brand image and is located outside at various places for decoration using various characters and design and materials.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.245-248
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• 2011

Many researches have been carried out to improve light absorption in the crystalline silicon solar cell fabrication. The rear reflection is applied to increase the path length of light, resulting in the light absorption enhancement and thus the efficiency improvement mainly due to increase in short circuit current. In this paper, we manufactured the silicon solar cell using the mono crystalline silicon wafers with $156{\times}156mm^2$, 0.5~3.0 ${\Omega}{\cdot}cm$ of resistivity and p-type. After saw damage removal, the dielectric film ($SiN_x$)on the back surface was deposited, followed by surface texturing in the KOH solution. It resulted in single-side texturing wafer. Then the dielectric film was removed in the HF solution. The silicon wafers were doped with phosphorus by $POCl_3$ with the sheet resistance 50 ${\Omega}/{\Box}$ and then the silicon nitride was deposited on the front surface by the PECVD with 80nm thickness. The electrodes were formed by screen-printing with Ag and Al paste for front and back surface, respectively. The reflectance and transmittance for the single-sided and double-sided textured wafers were compared. The double-sided textured wafer showed higher reflectance and lower transmittance at the long wavelength region, compared to single-sided. The completed crystalline silicon solar cells with different back surface texture showed the conversion efficiency of 17.4% for the single sided and 17.3% for the double sided. The efficiency improvement with single-sided textured solar cell resulted from reflectance increase on back surface and light absorption enhancement.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.77-82
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• 2004

The purpose of this study is to establish a reference for image acquisition for completion of a standard brain for diverse Korean population, and to develop a management system that saves and manage database of the acquired brain image and personal information of those who were tested. 3D MP-RAGE technique, which has excellent SNR and CNR and reduces the times for image acquisition, was selected for anatomical Image acquisition, and parameter values were obtained for the optimal image acquisition. The database management system was devised to obtain not only anatomical image data but also subjects' basic demographic factors, medical history, handedness inventory state-trait anxiety inventory, A-type personality inventory, self-assessment depression inventory questionnaires of Sasang Constitution Mini-Mental State Examination, intelligence test, and personality test via a survey questionnaire and to save and manage the results of the tests. In addition, this system was designed to have functions of saving, inserting, deleting, searching, and Printing of image da a and personal information of subjects, and to have accessibility to them as well as automatic connection setup with ODBC. This newly developed system may have major contribution to the completion of a standard brain of diverse Korean population in that it can save and manage their image date and personal information.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1436-1441
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• 2004

Abnormal current-voltage characteristics of an oxide semiconductor have been investigated and a novel method of detecting reducing gases utilizing self-heating mechanism of sensing layer without an additional heater has been developed. Planar-type sensors based on WO3-doped SnO2 were fabricated using a screen-printing technique. The applied voltage across the sensing layer caused heating of the sensing layer and the current abruptly varied upon exposure to a gas mostly as a result of surface reactions. A unique and fascinating aspect of the gas sensing scheme is that no additional heater is necessary for detection. The new sensing method has been applied to C2H5OH gas in this preliminary work.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.635-638
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• 2018

The Cost for introducing smart factory will decrease and the service type will change from a large scale to small quantity manufacturing, when 3D printing technologies have actively applied and smart factory related technologies have more stably developed. If customers have to provide private information, the availability of developed technology may cause slow progress. We propose a new protocol for custom manufacturing service of smart factory. The proposed approach is designed for smart contract based IoT convergence network. We analyzed the requirements of the proposed approach which provides anonymity, privacy, fairness, and non-repudiation. We compared it with closely related studies to show originality and differences.

• Elastomers and Composites
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• v.6 no.1
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• pp.71-81
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• 1971

The intention of this study is to investigate the properties of polymer blend, NBR/PVC vulcanizates and blending procedures such as roll-mixing temperatures and sequences for polymer blending of NBR and PVC(resin type). The results obtained are as follows: 1. The roll temperature applied for polymer blending is around $150^{\circ}C$. At this temperature region, the degradation of rubber stock, which may be caused by heat, can be minimized and mill processing in practical application in industries can also be facilitated. 2. It is obviously necessary that a small amount of plasticizers should be added to the stock for improving processibility of roll mixing and physical properties. 3. On roll-mixing sequence, it is more effective that PVC compounded with plasticizer is added to NBR milled on hot roll. 4. The vulcanizates of the blends with different degree of polymerization of PVC ale similar to one another in properties. 5. NBR/PVC(70/30) blends shows the better physical characters than eve,-made foreign latex blend except abrasion-resistance. 6. As PVC addition ratio is increased, the physical properties such as resistance to ozone, tear, heat and oil and tensile strength, modulus, hardness have also improved, on the other hand, tension set and rebound character decreased. 7. The curve of ultimate elongation have point of inflection at the ratio of $30\sim40$ part of PVC. 8. While CR is blended, the physical properties such as brittle point, rebound and resistance to oil in high temperature have improved. 9. Polymer blend of NBR and domestic PVC is applied for the industrial utility such as rubber sole and heel, electric wire cover and oil-resistant packing, coating and gasket, printing roll, film for food packing etc.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.146-154
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• 2011

The adhesive-tape of a liquid leak film sensor including the alarm system is developed. The sensing film is composed of three layers such as base film layer, conductive line layer, and protection film layer. The thickness of film is 300~500 um, the width is 3.55 cm, and the unit length is 200 m. On the conductive line layer, three conducting lines and one resistive line are formulated by the electronic printing method with a conducting ink of silver-nano size. When a liquid leaks for the electricity to be conducted between the conductive line and the resistive line, the position of leakage is monitored by measuring the voltage varied according to the change of resistance between two lines. The error range of sensing position of 200 m film sensor is ${\pm}1m$.