• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.454-462
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• 2006

To enhance the competitive edge of the material cost, various techniques lowering the material cost of inverter to drive Cold Cathode Fluorescent Lamp (CCFL) have been developed. In this paper, the theoretical analysis has been done for the existing techniques such as Jin Balance and O2Micro technique. Especially, How to design the value of magnetizing inductance to meet the specification of the lamp current tolerance between lamps has been disclosed. Based on this result, two kinds of hybrid type balancing techniques have been proposed and analyzed mathematically, Also, the accuracy of the proposed techniques has been verified through Pspice simulation.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.88.1-88
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• 2003

Antogonistic bacteria against Rhizoctonia solani and Pythium spp., causing serious damage to golf course grasses, were isolated from the top soil of several golf courses in Korea. The isolate of Limk0102 was selected as the biological agent by characterization of antifungal activity, large scale preparation, fungicides tolerance and ecological fitness to the targe environment. The isolate was identified as Bacillus subtilis by biochemical and physiological characterization, and 165 rDNA sequence analysis. The bacterial agent was formulated as a granule type by seeding it on fine sand. The formulated agent showed high recovery rate (more than 10$\^$8/ cells/g sand) even after 6 month-storage at room temperature with similar antifungal activity with that of original cells. In vitro, the biological agent successfully exhibited antagonistic performance on bentgrass inoculated with R. solani or Pythium spp. isolated from the diseased grasses on golf courses. Field evaluation on disease control activity and ecological fitness of the agent is now under going on several golf courses.

• The KSFM Journal of Fluid Machinery
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• v.5 no.3 s.16
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• pp.40-45
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• 2002

Since the previous cut-and-try design algorithm requires much cost and time, the automated design technique with the CFD and optimum design algorithm has recently been concerned. In this work, the Navier-Stokes equation was solved to gain more detailed viscous flow information of cascade with rotor-stator interactions. The H-grid embedded by O-grid was generated to obtain more accurate solution by eliminating the branch cut of H-grid near airfoil surface. To handle the relative motion of the rotor to the stationary stator, the sliding multiblock method was applied and the cubic-spline interpolation was used on the block interface boundary. To validate present procedure, the time-averaged aerodynamic loads were compared with experimeatal data. A good agreement was obtained. The Modified Method of Feasible Direction (MMFD) was used to carry out the sensitivity analysis of the change of aerodynamic performance by the changes of the cascade geometry. The present optimization of the cascade gave a dramatic reduction of the drag while the lift maintains at the value within the user-specified tolerance.

• ETRI Journal
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• v.36 no.3
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• pp.418-428
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• 2014

In social network services, such as Facebook, Google+, Twitter, and certain postings attract more people than others. In this paper, we propose a novel method for predicting the lifespan and retweet times of tweets, the latter being a proxy for measuring the popularity of a tweet. We extract information from retweet graphs, such as posting times; and social, local, and content features, so as to construct prediction knowledge bases. Tweets with a similar topic, retweet pattern, and properties are sequentially extracted from the knowledge base and then used to make a prediction. To evaluate the performance of our model, we collected tweets on Twitter from June 2012 to October 2012. We compared our model with conventional models according to the prediction goal. For the lifespan prediction of a tweet, our model can reduce the time tolerance of a tweet lifespan by about four hours, compared with conventional models. In terms of prediction of the retweet times, our model achieved a significantly outstanding precision of about 50%, which is much higher than two of the conventional models showing a precision of around 30% and 20%, respectively.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.5
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• pp.19-27
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• 2016

This study is to find appropriate plant for infiltration swale (which is natural LID infrastructure) and suggest basic research database for building infrastructure of LID facilities. Through the research inside, it first selects the plant strong to flooding and salt tolerance. Also, the research built infiltration swale along the road, planted those strong plants and monitored how well those plants adapted into the environment. Particularly, it showered 72mm/hr-speed artificial shower, also with natural shower, given that plants were vulnerable to flood because of influx of the rain. As a result of field applicability monitoring, Pennisetum alopecuroides and Equisetum hyemale (which degrade the pollutant well and adapt into rainy environment) are planting individually, or Juncus effusus var. decipiens, Liriope platyphylla, Miscanthus sinensis Andersson, Euonymus japonica (which are strong to rainy environment) and Pennisetum alopecuroides and Equisetum hyemale are mixed planting. The research should have monitored the plant for more than one year to study them, but the research only lasted five months. Therefore, it is hard to generalize. After all, through the long term research, it should pursue study more on appropriate plant materials and database that can be the reference for infrastructure establishment and maintenance.

• Journal of Life Science
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• v.11 no.1
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• pp.30-33
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• 2001

To identify novel components involved in the salt stress signaling pathway of yeast cells, we used mTn3-mediated transposon tagging library and screened mutants displaying enhanced tolerance to NaCl. Southern blot analysis indicated that more than 80% of the sre (salt resistant) mutants possessed only one insertion of the tagged transposon, suggesting that the NaCl resistant phenotype was mediated by a single gene in the majority of the mutants. To define the role of SRE genes in the salt stress signaling pathway, we introduced NaCl stress-inducible ENA1::LacZ construct into the sre mutants and examined the expression of ${\beta}$-galactosidase activity. Interestingly, we could detect high level of ${\beta}$-galactosidase activity without any NaCl treatment in the sre-3, 4, 6 and 7 mutants. These results indicate that SRE-3, 4, and 7 gene are components of salt stress signaling pathway of yeast cells.

• Journal of Korean Society for Quality Management
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• v.42 no.3
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• pp.301-310
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• 2014

Purpose: The purpose of this study is to improve a mechanism of expendable bathythermograph measurement by balancing wire resistances between plus wire part and minus wire part and by removing effects of sea water resistance between XBT(Expendable Bathythermograph) and temperature recorder. Methods: The problems are exactly found out through the analysis of XBT and temperature recorder circuit. A process of XBT manufacturing that balances wire resistances between plus wire part and minus wire part is added. Results: The results of this study are as follows; the complicated test process such as temperature accuracy test with a cistern is substituted with a simple process of XBT manufacturing such as balancing wire resistances between plus wire part and minus wire part. Then, the temperature accuracy tolerance of XBT is improved up to ${\pm}0.1^{\circ}C$. Conclusion: Consequently, balancing wire resistances and removing effects of sea water resistance improve temperature accuracy of XBT and reduce expensive and harassing process of XBT manufacturing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1749-1752
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• 2005

High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evaluation of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.147-155
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• 2006

High speed machining has become the main issue of metal rutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evolution of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.110-117
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• 2011

The purpose of this work is to develop of a press forming process for mobile phone battery cover as an alternative to the current manufacturing process by laser welding. This press forming process consists of a combination of bending, side pressing and side bending operations. The dimensional error for each process was investigated by finite element(FE) analysis and the Taguchi optimization method. The spreading of the cover width in the side pressing process was adjusted by modifying the blank shape with a notch. The over-bending method was adopted to compensate the spring-back which occurs after bending. Forming experiments were performed to verify the reliability of the developed press forming process. In addition, the strength of the product was evaluated to verify the suitability of the battery cover manufactured with this new press forming process. The results of the forming experiments indicate that the dimensional accuracy of the battery cover is within the required tolerance. The strength of the battery cover was evaluated to 547N which is larger than required strength of 400N.