• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.04a
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• pp.169-169
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• 2003

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.11a
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• pp.233-237
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• 2004

• The Mathematical Education
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• v.50 no.3
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• pp.337-354
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• 2011

The purpose of the study was to investigate how students understand multiplication and division of fractions and how their understanding influences the solutions of fractional word problems. Thirteen students from 5th to 6th grades were involved in the study. Students' understanding of operations with fractions was categorized into "a part of the parts", "multiplicative comparison", "equal groups", "area of a rectangular", and "computational procedures of fractional multiplication (e.g., multiply the numerators and denominators separately)" for multiplications, and "sharing", "measuring", "multiplicative inverse", and "computational procedures of fractional division (e.g., multiply by the reciprocal)" for divisions. Most students understood multiplications as a situation of multiplicative comparison, and divisions as a situation of measuring. In addition, some students understood operations of fractions as computational procedures without associating these operations with the particular situations (e.g., equal groups, sharing). Most students tended to solve the word problems based on their semantic structure of these operations. Students with the same understanding of multiplication and division of fractions showed some commonalities during solving word problems. Particularly, some students who understood operations on fractions as computational procedures without assigning meanings could not solve word problems with fractions successfully compared to other students.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.575-581
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• 1988

To integrate the two-dimensional Navier-Stokes equations numerically in multiply-connected flow regions, the vorticity-stream function formulation is used. The steady stream function value at the surface of the multibody, initially unknown, has been determined interactively by introducing a line integral which requires the single-valuedness of pressure at each interaction step. This procedure is relatively simpler and more efficient than the primitive variable formulation which requires much more computing time and shows poor convergence. Three doubly-connected flow problems are defined and numerically analyzed by the present method. The results have been compared either with earlier existing ones or with the experimental interferograms to demon-strate the validity of the presented method.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.20-23
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• 2012

With continuous development of the 2nd generation HTS conductor, the critical current of the conductor is also increasing. However, many applications require more than 2 conductors in parallel to transport large current. Applications such as HTS power cables and some HTS current leads usually need much larger transport current than that provided by a single conductor and they require more than several tens of HTS conductors. In the case of parallel connection of multiple HTS conductors, the current distribution depends on the contact resistance of each conductor at the terminals for DC operation. The non-uniform distribution of the terminal resistances results in a non-uniform distribution of the current. The resultant current non-uniformity affects on the measurement of the I-V curve and the thermal performance of the multiple conductors. This paper describes the I-V curves obtained from multiply connected HTS conductors with different terminal contact resistances to investigate the relationship between the distorted I-V curve and heat generation.

• Journal of the Korean Society of Costume
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• v.51 no.8
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• pp.1-12
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• 2001

An empirical review on silk fabrics of the Chosen period showed that they varied in kind and design according to their uses. Thus the purpose of this study is to classify the fabrics into temple and excavated fabrics according to their uses and collected places and then to examine characteristics of each type. Concerning fabrics collected in temples. satin was most used, followed by twill, tabby, multiply, leno and gauze and clossing fabrics in order. Tabby and silk fabrics used Ju(紬) as their main material. Cho( ) was much more used in fabrics collected in temples than in excavated ones. This indicate that Cho( ), more luxurious than Ju(紬), had divine applications such as covering Buddha s bones of temples. Brilliant, colorful multiply fabrics using goldern and color threads had high effects of ornamenting altar covers, umbrellas, surplices and palanquins. Fabrics held in temples adapted composite designs, in which more than two shapes were used, rather than single ones. Single designs employed plant shapes in most cases. followed by treasures pattern, geometrical, cloud and animal shapes in order. Most composite designs used a combination of animal and plant shapes, followed by plant and geometry, treasures pattern and plant, cloud and animal, and animal, treasures pattern and plant in order. Few excavated fabrics used animal designs while fabrics collected in temples were often designed with shapes of propitious animals such as dragon. Treasures pattern. representing a good omen of Buddhism, was often used sing1y or sometimes compositely with another design.nother design.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.1
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• pp.16-23
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• 2012

Use of security papers for monetary papers, gift certificates, and lottery tickets increases every year. As the use of security papers increase, there are more possibility of counterfeits. In this study, we used unique fibers from the sea to increase the difficulties against counterfeiting. The red algae fibers give opacity as much as calcium carbonates, and have unique shape in length ($500{\sim}900\;{\mu}m$) and width ($1{\sim}4\;{\mu}m$) to be discerned from other natural fibers such as wood and cotton fibers. We mixed red algae fibers to wood fibers in a series of fixed ratios to make single and multiply papers for making security papers. Paper with dyed red algae fibers were also used. Paper made without fillers gave enough opacity for printing when red algae fibers were used more than 20% of the fiber furnish. Those properties may allow red algae fibers to be a potential candidate for fiber raw materials of security paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.46-51
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• 2003

The charcoal is known to have gas adsorption capability and is used frequently to mitigate the unpleasant smells from food and clothing. It is also used to treat water to remove dissolved organic and inorganic substances. In this paper, we applied the several different kinds of charcoals to the papers in three different ways to investigate if charcoal application method affects its gas adsorption capability. Wet end addition, making multiply, and coating method were tested. Specific ethylene gas adsorption capabilities were measured. Experimental results shows that manufacturing conditions of the charcoal itself changed its gas adsorption properties. The boxes used for agricultural produces, and the packaging paper for flowers are to be well fitted application for the charcoal added paper. Mulch paper, which needs opacity and air permeability with proper strength properties, is another candidate for the application of charcoal added paper.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.113-120
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• 2014

In this paper, I present a new echo canceller using the adaptive cascade system identification (CSI) method, which a system response is divided into several responses so that each response is adaptively estimated and combined. Echo cancellation is required for a dual-duplex DSL, in order to allow each individual loop to operate in a full duplex fashion. Echo cancellation was one of the most difficult aspects of DSL design, requiring high linearity and total echo return loss in excess of 70 dB. Especially, for a fickle response, if the response is estimated by an adaptive filter, the filter needs more taps and the performance is decreased. But the response is divided into several responses, the computation complexities are decreased and the performance is increased. For the stage constant n, which represents the number of stages, if the response is not divided (n=1), the computation complexity of multiply is $2N^2$. And if the response is divided into two responses (n=2), the computation complexity of multiply is $2N^2$. Also, if n=3, the computation complexity is ${\frac{2}{3}}N^2$. Therefore, it is known that the computation complexity is decreased as n is increased. Finally, this proposed method is verified through simulation of echo canceller for digital subscriber line (DSL) application.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1216-1218
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• 2005

A high temperature superconducting power transformer gets its advantages over the conventional ones when the rated capacity of the HTS transformer becomes 30 MVA or more. The standard capacity of the recent 154 kV/ 22.9 kV power transformer is 3 phase 60 MVA in Korea which means that the rated current of the secondary becomes more than 1,500 amps. Considering the current capacities of the HTS wires being developed recently, it is inevitable to use the HTS wires in parallel in order to be applied to the power transformer. But nonuniform distribution of currents and large AC losses are major problems in parallel HTS windings setting aside the difficulties of making parallel windings. To solve these problems, several kinds of multiply laminated HTS wires were fabricated and tested for the application of these multiple wire to an HTS power transformer. Test results were compared with that of each other and the best were selected for the application to an HTS power transformer.