• Journal of Conservation Science
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• v.37 no.5
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• pp.525-535
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• 2021

This study identified material properties through scientific analysis on Jikgeumdan(satin with gold threads) from Donggungbi-Wonsam and the gold threads used in the embroidery. The Donggungbi-Wonsam's base of gold threads were estimated to have used mulberry fiber's Korean paper(Hanji) because non-wood-based fibers were observed. The X-ray spectrometer showed that the Tongsuseulan of Donggungbi-Wonsam was a flat gold thread of pure gold and Jikgeumdan of flat silver thread of its Saekdong and Hansam. High sulfur levels were detected in the flat silver thread, which appeared to have formed silver sulfide by either manufacturing process using sulfur or conservation environment. he dragon insignia's embroidery is also described as two types twisted gold threads; pure gold and alloying-gold and silver. while dragon insignia's border line is decorated with a twisted gold thread of pure gold. In particular, it was investigated that adhesives such as an animal glue, a protein-based compound by gas chromatography mass spectrometry. Additionally, XRF and Raman spectroscopy analysis on the mixture substances between the metal surface and the base paper of gold threads identified talc and quartz in the gold threads and Seokganju(hematite) in the flat silver threads.

• Composites Research
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• v.30 no.6
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• pp.331-337
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• 2017

The composite lattice structures have advantages of high specific stiffness and strength and are mainly applied to the structures of launch vehicles that carry the compressive load. However, since these structures are manufactured by filament winding technology, there are some defects and voids found in the knots. For these reasons, the stiffness and strength of the lattice structures have to be compared with finite element model for predicting design load. But, the full scale test is difficult because time and space are limited and the shape of structure is complex, and hence the simple and reliable test methods for examination of stiffness are needed. In this paper, subelements of composite lattice structures were prepared and compressive and bending test were conducted for examination of stiffness of helical and hoop rib. Test methods for subelements of composite lattice structures that has curved and twisted shape were supposed and compared with finite element analysis results.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.6
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• pp.22-40
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• 2015

Cellulose fibers is one of the most abundant in nature. It has many distinctive features: abundant in nature, biodegradable, non-toxic, eco-friendly, sustainable, easy to fabricate, hydrophilic, and cost-effective. Cellulose fibers, known as pulp, is produced from cellulose-containing materials by the pulping process. As the raw material, wood has been most commonly used while recycled pulp has been also used to some degree. Thus, pulp usually refers to wood pulp. Generally, the pulp and paper industry is regarded as the commodity market where the cost should be much more important than the quality. It also belongs to a mature market where the growth is slow, or even in decline. Accordingly, technological development has been rather stagnant for the industry. Recently, however, the pulp and paper industry has faced very serious challenges. First, due to digital technology, there has been a steady decline in the need for pulp and paper products. The digital industry has continuously replaced printed products such as books, newspapers, and magazines. Second, there has been a trend initiated by developed countries to limit the use of wood as the raw material for the sake of environmental protection. This forces the industry to find a more efficient use of wood pulp as well as finding alternative, non-wood sources. Third, as an individual becomes wealthier and more conscious of health-care, the quality of a product becomes more important than the cost. Thus, a paradigm shift is needed from the cost-conscientious to the quality conscientious. The objective of this article is to review the technologies aimed at engineering cellulose fibers for producing high-value added paper products.

• Fibers and Polymers
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• v.7 no.3
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• pp.317-322
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• 2006

Reduction of yam hairiness by nozzles in ring spinning and winding is a new approach. Simulation of the airflow pattern inside the nozzles provides useful information about actual mechanism of hairiness reduction. The swirling air current inside the nozzles is capable of wrapping the protruding hairs around the yam body, thereby reducing yam hairiness. Since production rate of winding is very high and the process itself increases yarn hairiness any method to reduce the hairiness of yarns at this stage is a novel approach. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern inside the nozzles using Fluent 6.1 software. In this study, both S- and Z-type nozzles having an axial angle of 500 and diameter of 2.2 mm were used for simulation studies. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential to the inner walls of the nozzles. S- and Z-twisted yams of 30 tex were spun with and without nozzles and were tested for hairiness, tensile and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e. the S3 values) for yam spun with nozzle is nearly 49-51 % less than that of ring yams in case of nozzle-ring spinning, and 15 % less in case of nozzle-winding, while both the yarn types show little difference in evenness and tensile properties. Upward airflow gives best results in terms of hairiness reduction for nozzle-ring and nozzle wound yams compared to ring yarns. Yarn passing through the centre of the nozzle shows maximum reduction in S3 values.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1079-1082
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• 2015

In Article 23 of Technical regulations for Telecommunication Line and Facilities, we have criteria of separation distance between telecommunication lines and power lines, and its related exceptional conditions. However, this is a conflicts condition with Article 32 that provides the type of indoor telecommunication cables such as twisted-pair cables and optical fiber cables. Also, it is frequently raised that exceptional condition related the PoE cables with up to 15.4W is improved to accept PoE cables with up to 30W. In this paper, we have proposed improvement plans of Technical regulations for separation distance between telecommunication lines and power lines by analyzing the variety of standard specifications at home and abroad.

• Fashion & Textile Research Journal
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• v.5 no.3
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• pp.299-303
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• 2003

Some of historical textiles were analyzed to identify the imprinted textures on the metal remains of Haengyeup(a horse strap pendant) and Doja (a knife), which were excavated in the ruins of Hwangsung-dong, Kyungju city in the fifth century and textiles imprinted on the human bones that were excavated in the Pungnae 4th Area, Namyangju county in the sixteenth century. The results analyzed arc as follows ; It was confirmed that the imprinted textures of Haengyeup and Doja are white ramie since the structural characteristics of cellulosic bast fibers, partially projected long oval cross sections with large lumens and the imprinted textures of human bones are silk fabrics since the triangular cross sections of fibroin is showed. All of the textiles were designed in plain weaves. In the case of weaving yarns, the warp threads were thicker than the weft threads, that is, the imprinted textures of Haengyeup were measured by 1.35 mm for warp and 1.21 mm for weft, and the Doja by 1.16mm for warp and 1.11 mm for weft. In connection with the direction of the yarn twist, the Z-twist were observed in the imprinted textures of human bones, whereas it presented the S-twist in the case of Haengyeup and Doja. The warp yarns were mostly harder twisted than the weft yarns on the amounts of twist, that is, it was observed that the case of Haengyeup were amounted to 0.33 twists per centimeter for warp yarns and 0.25 twists per centimeter for weft yarns. Also it was showed 0.32 twists per centimeter for warp yarns and 0.26 twists per centimeter in the case of the textures of human bones. On the fabric counts, it was showed that the finer the yarns the higher the densities since it were $4.3{\times}5.1$ threads per sqaure centimeters and $7.6{\times}7.1$ threads per sqaure centimeters each in the case of Haengyeup and Doja, whereas it was $18.2{\times}33.7$ threads per sqaure centimeters in the case of the textures of human bones.

• Composites Research
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• v.12 no.6
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• pp.74-82
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• 1999

The static and fatigue characteristics of polyurethane foam cored sandwich structures are investigated. Three types of the specimens with the glass fabric faces and the polyurethane foam core are used; non-stitched. stitched, and stiffened sandwich specimen. Especially additional structural reinforcements with the twisted polyester and glass fiber for thickness direction are made to stitched sandwich structure panel to minimize the delamination of structure which is stitched the upper and lower faces through the core and the resin is impregnated Into stitched fiber with the characteristics of low viscosity of resin at resin flow temperature and cured together with during the curing process. Bending strength of stitched specimen which is 50 mm $50{\times}50{\;}mm$ pitched is improved by 50 % as com-pared with non-stitched specimen and stiffened specimen is improved 10 times more than non-stitched structure. After fatigue testing of $10^6$cycles by 20% of ultimate load under monotonic load, the bending fatigue strength of non-stitched specimen is decreased by 27% of monotonic bending strength, 39% for stitched structure and 20% for stiffened specimen. To verify the aging effect of polyurethane form core, Ultrasonic C-scanning equipment is used to detect the damage of skin laminate alone after fatigue test. From results of UT C-scan images, there is no defect that can be damaged occurred during fatigue test. It is concluded that the decrease of bending strength for foam cored sandwich specimen is caused by the decrease of stiffness due to the aging of polyurethane foam core during fatigue cycles.