• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.21-25
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• 2006

This paper describes the novel control techniques design of VSC(Voltage Sag Corrector) for the purpose of power line quality enhancement. A fast detecting technique of voltage sag is implemented through the detection of instantaneous value on synchronous rotating do-reference frame. The first order digital filter is added in the detection algorithm to protect the insensitive characteristics against the noise. The relationship between the total detection time and cut-off frequency of the filter is described. The size of the capacitor bank used as the energy storage element is designed from the point of view of input/output energy with circuit analysis. Finally, the validity of the proposed scheme is proven through the simulated results.

• KSBB Journal
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• v.13 no.3
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• pp.308-311
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• 1998

A novel process was developed to simultaneously produce invertase and yeast extract from baker's yeast using ultrafiltration (UF) and microfiltration (MF) membrane processing. After the extraction of invertase under the optimal condition obtained in this study, invertase was separated from yeast cells using a hollow fiber membrane with a pore size of 0.1 $\mu\textrm{m}$. The resulting permeate containing invertase was concentrated using a hollow fiber membrane with a nominal molecular weight cut-off of 30 kDa. The yeast cell and permeate solutions, which were obtained after MF and UF membrane processing, respectively, were mixed together, and the autolysis was performed at 50$^{\circ}C$ in the presence of 5% (w/v) ethanol and 1% (w/v) NaCl. As a result, the yeast extract and invertase could be simultaneously produced from baker's yeast by this novel process.

• Communications of Mathematical Education
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• v.19 no.4 s.24
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• pp.805-822
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• 2005

In Korea, many local university mathematics faculty knew that the institution faced serious student shortage problems and the restructuring and cut actions for such a mathematics major programs. In general, undergraduate mathematics education in korea is in the crisis. In general, lots of mathematics departments in korea was not prepared for such a severe risk. In this article, university mathematics education and research business are studied in the context of the size of korea-usa population, economy(such as GDP), SCI indices. Korea-usa university mathematics education profile data are presented to compare korea-usa university mathematics education business. Lots of precious data on mathematics education are being helped to prepare for the university mathematics education crisis.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.63-68
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• 2005

In this paper, Coplanar Waveguide(CPW) low-pass filter with the spurious-reduced is designed by using Defected Ground Structures(DGS). Two different LPF unit cells and DGS pattern are combined to reduce the spurious. In comparison to a conventional step impedance LPF, the size of proposed LPF as 17.2mm*6.8mm is several times smaller. The simulation and measurements confirm that spurious characteristics is presented less than -30dB($S_{21}$) to three times cut off frequency.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.67-70
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• 2005

The carbon fiber reinforced/epoxy laminated composites were fabricated with initial fiber failures within the unidirectional fiber pre-pregnated ply. The fiber failures were made intentionally either parallel to and/or perpendicular to the unidirectional fibers within the ply. The pre-made clear-cut cracks were found to be healed partially after laminating process. The laminates were impacted with or without initial fiber failures within the laminates. The force versus deflection curves were compared. The partially healed laminates showed the reduced laminate stiffness as compared to those without any intentional fiber failures. The impact curves were compared with size and the location of the initial failures varied.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.2
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• pp.89-94
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• 1977

So far, high accuracy in-process sensors have been used for controlling the cutting tool, but the method followed in this new system is guite different form previous processes. In this system, after the rough cut the mark indication the pasition of the finished size in put on the cutting surface of the workpiece by ultrasonic or vibration cutting. The cutting is then continued until the mark just disappears, This position being observed by the used of a simple in-proces sensor, The in-prosess sensor in used only to detect the existence or dis apperance of the mark.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.298-303
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• 2004

parameters in surface grinding. Taguchi method which is one of the design of experiments has been introduced in achieving the aims. The process parameters were the grain size, the wheel speed, the depth of cut and the table speed. The effect of the process parameters on the geometric error was examined and an optimal set of the parameters was selected to minimize the geometric error within the controllable range of the used grinding machine. The reliability of the results was evaluated by the ANOVA.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.59-64
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• 2002

Recently the applications of high speed machining are increasing due to the need for high performance and high accuracy machining and machining for difficult-to-cut material. However, the high speed machining also accompanies some problems: the product quality can be degraded due to the tool wear and the product cast can go up due to frequent tool replacements. Therefore, it is necessary to develop a technique of quantitative tool wear measurement to determine the precise timing for tool replacement. In this respect, this study suggests a reliable technique far the reduction of error components by developing a system using a CCD camera and an exclusive jig to be able to precisely measure the size of tool wear in flat end mill for high speed machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.83-88
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• 1993

Recently, the analysis of microcutting with submicrometer depth of cut is tried to get a more high quality surface product, but to get a valuable result another method instead of conventional finite element method must be considered because finite elment method is impossible for a very small focused region and mesh size. As the altermative method, Molecular Dynamics or Statics is suggested and acceoted in the field of microcutting, indentation and crack propagation. In this paper using Molecuar Dynamics simulation, the phenomena of microcutting with subnanometer chip thickness is studied and the cutting mechanism for tool edge configuration is evaluated. As the result of simulation the atomistic chip formation is achieved.

• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.30-47
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• 2004

This research considers a Network Diversion Problem (NDP) in the directed graph, which is to identify a minimum cost set of links to cut so that any communication paths from a designated source node to a destination node must include at least one link from a specified set of arcs which is called the diversion arcs. We identify a redundant constraint from an earlier formulation. The problem is known to be NP-hard, however a detailed proof has not been given. We provide the proof of the NP-hardness of this problem. We develop a tabu search algorithm that includes a preprocessing procedure with two steps for removing diversion arcs as well as reducing the problem size. Computational results of the algorithm on instances of general graphs and grid graphs are reported.