• Journal of the Korea Society of Computer and Information
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• v.20 no.12
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• pp.61-66
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• 2015

In this paper, we draw a security assessment by analyzing possible vulnerabilities of the designated PC service which is supposed for strengthening security of current online identification methods that provide various areas such as the online banking and a game and so on. There is a difference between the designated PC service and online identification methods. Online identification methods authenticate an user by the user's private information or the user's knowledge-based information, though the designated PC service authenticates a hardware-based unique information of the user's PC. For this reason, high task significance services employ with online identification methods and the designated PC service for improving security multiply. Nevertheless, the security assessment of the designated PC service has been absent and possible vulnerabilities of the designated PC service are counterfeiter and falsification when the hardware-based unique-information is extracted on the user's PC and sent an authentication server. Therefore, in this paper, we analyze possible vulnerabilities of the designated PC service and draw the security assessment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.3
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• pp.12-23
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• 2007

Frequently spraying of natural starch slurry onto the formed wet web has been adopted to improve properties of paperboards. This conventional starch spraying technique, however, becomes less effective in strength improvement. In this study the effects of various factors including wet web dryness, quantity of starch slurry sprayed, and drying temperature on paperboard properties were investigated. Migration of starch granules into the webs appeared to cause a reduction in plybond strength when the web dryness was lower than this level. Wet webs should contain enough water to swell the starch granules, and at the same time they should be heated to a temperature high enough for complete cooking of the sprayed starches to occur. This suggested that preheating of the wet web can be employed to improve the plybond strength.

• Tribology and Lubricants
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• v.22 no.6
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• pp.307-313
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• 2006

In this paper, a theoretical analysis is carried out to study the effect of viscosity variation with pressure in multiply grooved moving hydraulic spool valves. Analytical expressions for pressure distribution in the clearance and leakage flowrate are obtained solving one-dimensional Reynolds. For constant viscosity, an analytical expression for lateral force is also presented. The results showed that variation of viscosity with pressure affect highly on pressure distribution, leakage flowrate and lateral forces in hydraulic spool valves. Therefore additional intensive studies, including numerical analysis for two-dimensional Reynolds, should be required to investigate detailed lubrication characteristics of spool valves for high pressure.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.624-626
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• 1998

In this paper. a new simple and efficient technique to improve the convergence speed of LMS algorithm is introduced. The convergence characteristics of the proposed algorithm, whose coefficients are multiply adapted in a symbol time period by recycling the received data, are analysis to prove theoretically the improvement of convergence speed. The theoretical analysis shows that the data-recycling LMS technique can increase convergence speed by (B+1) times, where B is the number of recycled data. The results of the computer simulation demonstrate that the simulation results are in accordance with the theoretical analysis and the superiority of the filter algorithm

• Research in Mathematical Education
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• v.17 no.1
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• pp.15-27
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• 2013

Division of fractions is always a difficult topic for primary school students. Most of the presentations in teaching the topic in textbooks are procedural, asking students to invert the second fraction and multiply it with the first one, that is, $$\frac{a}{b}{\div}\frac{c}{d}=\frac{a}{b}{\times}\frac{d}{c}$$. Such procedural approach in teaching diminishes both the understanding of structure in mathematics and the interest in learning the subject. This paper discussed the formulation of teaching the division of fractions, which based on research lessons in some primary five classrooms. The formulated lessons started with an analogy to division of integers and working with division of fractions with equal denominators and then extended to division of fractions in general. It is found that the using of analogy helps students to invent their procedure in working the division problem. Some procedures found by students are discussed, with the focus on the development of their invention and mathematical thinking.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1233-1240
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• 2004

Recently the need for cooperative control among robots is increasing in a variety of industrial robot applications. Such a control framework enhances the efficiency of the real robotic assembly environment along with extending the robot application. In this paper, an ethernet-based cooperative control framework was proposed. The cooperative control of robots can multiply the handling capacity of robot system, and make it possible to implement jigless cooperation, due to realization of trajectory-synchronized movement between a master robot and slave robots. Coordinate transformation was used to relate among robots in a common coordinate. An optimized ethernet protocol of HiNet was developed to maximize the speed of communication and to minimize the error of synchronous movement. The proposed algorithm and optimization of network protocol was tested in several class of robots.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.160-162
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• 1996

The estimation of AC losses is demanded for higher efficiency and stability in AC use of superconducting coils. Hysteresis loss occurred by a.c. transport current is called of self field loss, and it is major part of losses generated in a.c. superconducting wire in case of located in low external magnetic field as superconducting transformer with iron core, or in short twist pitch wire, multiply stacking cable. In this paper, we calculate self field loss of superconducting wire.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.166-170
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• 2010

To numerically calculate electromagnetic scattering from the electrical-large three-dimensional(3D) objects, the high-frequency approaches have been usually applied, but the accuracy and feasibility of these geometrical and physical optics(GO-PO) approaches, to some extent, are remained to be improved. In this paper, a new framework is developed for calculation of the near-field scattering field of an electrical-large 3D target by using a multilevel fast multipole algorithm(MLFMA) and generation of radar images by using a fast back-projection(FBP) algorithm. The MPI(Message Passing Interface) parallel computing is carried out to multiply the calculation efficiency greatly. Finally, a simple example of perfectly electrical conducting(PEC) patch and a canonical case of Fighting Falcon F-16 are presented.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.115-120
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• 2015

Until now, AOCS SW has used FPU which is one of CPU resources for satellite attitude control. And most of the SW Throughput was consumed to calculate Matrix Multiply. As SW throughput margin is decreasing seriously with shorter control period and more computational burden at next satellite programs, a dedicated HW matrix multiplier is absolutely required. This paper represents results of HW implementation & performance measurement and mentions several techniques for performance improvement, further works.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.470-473
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• 2003

We have the index form of the multiply warped products manifold. From this result we will investigate the physical properties on the Robertson-Walker spacetime. The singularly thorem are usually interpreted as an indication that black hole exist and that there has been a big bang. This paper include necessary condition for the Robertson-Walker spacetime with singularly.