• Structural Engineering and Mechanics
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• v.29 no.1
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• pp.55-75
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• 2008

In this paper, the behavior of two collinear Mode-I cracks in piezoelectric/piezomagnetic materials subjected to a uniform tension loading was investigated by the generalized Almansi's theorem. Through the Fourier transform, the problem can be solved with the help of two pairs of triple integral equations, in which the unknown variables were the jumps of displacements across the crack surfaces. To solve the triple integral equations, the jumps of displacements across the crack surfaces were directly expanded as a series of Jacobi polynomials to obtain the relations among the electric displacement intensity factors, the magnetic flux intensity factors and the stress intensity factors at the crack tips. The interaction of two collinear cracks was also discussed in the present paper.

• Fashion & Textile Research Journal
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• v.7 no.5
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• pp.472-480
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• 2005

It was proved the practical use of the unique traditional Korean paper through the previous researches. The purpose of this study was to suggest the adequate application which is making various applied patterns in the fashion products so as to contribute to textile, fashion, and Korean paper industry. Six kinds of vests with the same fashion material using the Korean traditional paper were manufactured in order to investigate the images of materials in case of wearing them on the actual human bodies. As the results of image assessment for the materials and the factor analysis, 'classical', 'natural', 'Korean traditional', 'rural' and 'luxury' images were presented as the representative image of the Korean traditional paper material. Making repeated patterns of stripes and zigzag by sewing-machine stitches showed the natural effect on Korean traditional paper. Well-matched harmony was shown between holes made by the needle in sewing and slits torn by the tension to the needle and the thread. Especially, transparency by irregular holes formed by artificial frictional washing could shown special formative arts harmoniously with semi-transparency of Korea traditional paper and touch of sewing yarn. After the unripe persimmon dyeing, holes made by the needle became more hard and tight. The changes were no longer shown by the artificial frictional washing and then fixed. As the result of applying the Korean traditional paper fashion materials with various patterns for the basic formed garments, it was shown that the common and simple garments were changed the garments with special formation which could be found on the art garments due to the creative touch and formative arts using the Korea traditional paper fashion material. A variety of formative application by means of the developed samples was suggested to enlarge the practicality. As the result of this study, it was discovered that the possibility and application of fashion goods through the developed samples made of Korean traditional paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.6
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• pp.58-69
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• 2012

As the meaning of dictionary terminology, scum refers to a layer of impurities that accumulates at the surface of a liquid. In papermaking process, scum indicates the floated solid waste generated by a flotation process during the primary wastewater treatment. In this study, different kinds of stocks and scums collected from newspaper, liner, tissue and fine paper were analysed in details. The purpose of this study was firstly to demonstrate the composition characteristics of different sources of scum, secondly the analysis of environmental hazardous materials, and thirdly the evaluation of reutilization ability of fibrous materials from collected scum. As mentioned the meaning of solid waste, scum was actually differ from the waste sludge in sources, compositions and recycling abilities. In the same manner of waste paper, the sludge which is generated within onsite of papermaking processes would be reused as a raw material. The general compositions of scum from waste water were mainly inorganic ash materials, fine fibre fractions, recycled fibre debries, and ink particles. If the scum is able to reuse as fibrous additives in papermaking process, it could contribute to the savings of running costs in both the subsidiaries of fibrous material and the solid waste treatment with even small quantity.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.5
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• pp.33-37
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• 2009

Hanji is a traditional Korean handmade paper, made of bast fibers of the paper mulberry. Its fiber furnish is much more expensive than wood fiber furnish. Hanji with a low basis weight requires additional opacity and smoothness for better writing and printing. Filler such as calcium carbonate can not be used to raise the opacity of Hanji because of its low retention in low basis weight paper and the high freeness of the Hanji fiber furnish. Addition of red algae pulp, which is prepared from marine red algae to the Hanji fiber furnish negated retention problems happening in the case of mineral filler addition, and produced a substantial improvement in the opacity and smoothness of Hanji. The higher retention was due to the much larger size of the red algae fibers compared to the mineral fillers. The improvement in opacity and smoothness were also due to the shape of the red algae fibers: that red algae fibers are narrower in widths and shorter in lengths than wood fibers results in increased surface area and smoothness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.5
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• pp.1-6
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• 2007

Formation which is one of the most fundamental characteristic of paper quality is affected by a number of variables. Fiber flocculation in the headbox has been recognized as the most important variable influencing formation. Consistency and crowding number of head box stock are known to represent the flocculation potential of stocks. The effects of consistency and crowding number on paper formation were studied by measuring the flocculation of fiber suspensions. Increasing consistency increased the degree of fiber flocculation. Especially the consistency of long fiber fraction was the most crucial factor of flocculation. Tensile strength of handsheets was furnish dependent rather than flocculation dependent. Crowding number of a furnish can be used for the characterization of stock flocculation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.476-486
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• 1995

In this paper, an attempt has been made to revise Raafat' s(1985) results on an inventory model for decaying raw materials and the finished product at a constant rate which was based on Goyal's integrated inventory model for a single product system. This paper is concerned with scheduling the frequencies of order quantity of several different raw materials on a production inventory model. The purpose of this paper is to present a simple method of deciding the frequencies of order quantity of raw materials, in the sense of minimizing the average total cost of the system. We describe on iterative procedure for directly determining near optimal frequencies of order quantity for the raw materials and the associated fundamental cycle time which can be used for constructing the production duration of the finished product. In cases where feasible schedules cannot be constructed using the values from the iterative procedure, the procedure provides a basis for changing the order quantity frequencies and the fundamental cycle time to obtain feasible schedules. An example is given to illustrate the derived results.

• ETRI Journal
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• v.39 no.1
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• pp.62-68
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• 2017

In this paper, we present the design and characterization analysis of a cascode GaN field-effect transistor (FET) for switching power conversion systems. To enable normally-off operation, a cascode GaN FET employs a low breakdown voltage (BV) enhancement-mode Si metal-oxide-semiconductor FET and a high-BV depletion-mode (D-mode) GaN FET. This paper demonstrates a normally-on D-mode GaN FET with high power density and high switching frequency, and presents a theoretical analysis of a hybrid cascode GaN FET design. A TO-254 packaged FET provides a drain current of 6.04 A at a drain voltage of 2 V, a BV of 520 V at a drain leakage current of $250{\mu}A$, and an on-resistance of $331m{\Omega}$. Finally, a boost converter is used to evaluate the performance of the cascode GaN FET in power conversion applications.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.26-33
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• 2014

Frankincense resin was applied to Hanji to improve its physical properties. The resin-treated paper showed the increasement of physical properties such as weight, thickness, and density. The highest increasement in weight and density of resin-treated paper were found at 30% treatment concentrations and the largest values of density were $41g/m^2$ Hanji. With the increasement of concentration, the brightness was decreased and transparency was improved. Of the mechanical properties of the paper, the tensile index and burst index showed the improved values. The tear index, however, was decreased. The frankincense resin showed the highest result in the tensile index of resin-treated paper and the basis weight of $41g/m^2$ Hanji. The air resistance of the resin-treated paper got improved with the increase of the concentration and $105g/m^2$ Hanji showed the highest values. The highest improvement in air resistance may make the resin-treated Hanji possible to use for semipermeable materials.

• 보존과학연구
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• s.17
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• pp.65-99
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• 1996

We exanmined the each effect of $NO_2$ and $SO_2$gas, the maincomponets of air pollutants, on the deterioration of 6 organic materials with Gasexposure cabinet. The organic materials were used 2 kind of papers(Korean paper, Oldbook paper) and 4 kind of textiles (Cotton, Silk, Hemp, ramie) in gas exposure experiments. In order to know how to change of physical conditions, the materials were exposed to 2000, 1000 ppm. h of $SO_2$dose, to 100 ppm. h of $NO_2$ dose at 65% RH. The color difference, tensile strength, elongation coeffient, mass reduction and fabric status of each materials were discussed the following below.1. The color difference of cotton and hemp was larger than that of silk and ramie in the presence of $SO_2$ gas. and the color difference of korean paper was less than that of the textile materials in the presence of $SO_2$ gas.2. The tensile strength of cotton fell suddenly at 100ppm.h of $SO_2$ dose and even became 56% of the unexposed cotton.3. The weight of 6 materials began to decrease in the presence of $SO_2$ gas.4. The tensile strength and elongation of the materials tended to decrease at 12.5ppm.h of $NO_2$ especially silk was the strongest tendency to decrease.5. Cotton, hemp and ramie were influenced by $SO_2$ gas more than by $NO_2$, but silk were influenced by $NO_2$ more thang by $SO_2$ at 10ppm.h of each noxious gas.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.385-392
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• 2016

Recently in the display industry, demands for high-luminance and resolution of display devices have been steadily increasing. Generally, micro linear patterns are applied to an optical film in order to improve its properties of light. However, these patterns are easily viewed to eyes and moire phenomenon can be occurred. Micro random patterns are proposed as a method to solve these problems, increasing light-luminance and light-diffusion. However, conventional pattern manufacturing technologies have long processing times and high costs making it difficult to apply to large area molds. In order to combat this issue, micro-random patterns are formed by using a roll to plate indentation method along with abrasive paper tools composed of AlSiO2, SiC, and diamond grains. Also, forming properties, such as size and fill-factor of random patterns, are analyzed depending on type, mesh of abrasive paper tools, and indentation forces.