• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1810-1812
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• 1997

This paper describes the results of ground fault analysis on HVDC Transmission Line using TNA (Transient Network Analyzer). The maximum overvoltage is about 1.7 p.u. in the case of single line to ground fault on the overhead transmission line. When the cable is linked to the end of the overhead transmission line, the maximum overvoltage is about 1.58 p.u..

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.11-15
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• 2002

In this paper, we have proposed the new configuration of wideband antenna using CPW fred lines. The proposed antenna has CPW feed lines and U-slot to achieve wade bandwidth with good impedance matching. The use of CPW feed line can decrease the number of substrates. It is compared with the conventional antenna find by a microstrip fled line. The parameters of CPW fred lines were studied by using the quasi-static approximation which is based on the conformal mapping method. The analysis of CPW discontinuities such as the tapered-step structure and the open ended gap were studied by using the quasi-static approximation which is based on the boundary element method. Also, the equivalent circuit model of multi-layer antenna were proposed using the cavity model. Experiment results of the proposed antenna 7how wide-bandwidth characteristics and good radiation patterns in passband.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1169-1173
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• 2006

Extracted fractions of the green seaweed Ulva lactuca were studied to verify the cytotoxicity and immunostimulating activity. The fractions from the ethanol extract of U. lactuca were prepared by the systematic extraction procedure with solvents such as hexane, ethyl ether, methanol, butanol and $H_2O$. The cytotoxic effects of U. lactuca fractions against human leukemia cell line U937, mouse neuroblastoma cell line (NB41A3), human hepatoma cell line (HepG2) and rat glioma cell line (C6) were investigated. Ethyl ether fraction showed the highest cytotoxicity against all four cell lines tested. In addition, $H_2O$ fraction also showed relatively high cytotoxicity. Dose dependent patterns were observed on all four cell lines. The immune-stimulating effects of U. lactuca fractions on rat macrophage cell line (RAW 264.7) were also investigated. All five fractions of U. lactuca extract stimulated NO production with concentration dependant manner. These results suggest that U. lactuca may be a useful candidate for a natural cancer preventing and immune-stimulating agents.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.274-282
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• 2011

The ultra slim U-I and W-I primary and pick-up coils for OLEV (On-Line Electric Vehicles) are proposed. With the proposed structures, the amount and the cost of the core are dramatically reduced. Not only air gap but also the lateral displacement are improved. The proposed structures are applied to the OLEV bus and SUV, which achieve 83% efficiency at 17cm air gap with more than 60kW output power, and the construction cost is lower than ￦300M/km. The proposed coil structures are verified with simulations and experiments.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.310-314
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• 2008

The exploitation of the wind energy resource is a rapidly growing area world-wide. The number of installed units is continuously increasing, and it is important to respect and to deal with the impact of wind turbine. This paper addresses the power quality characteristics of U57 Wind Turbine. 750kW gearless type wind turbine for low wind speed, named U57, is developed by UNISON. The power quality measurement system consists of measuring WTG output current, line-to line voltage and wind speed signal. With using measured data, power quality measurement is evaluated about maximum power, reactive power, voltage fluctuation, harmonics according to IEC 61400-21.

• Journal of The Korean Astronomical Society
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• v.27 no.2
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• pp.133-146
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• 1994

We have detected a SiO maser line (v=1, J=2- 1) for 15 stars out of about 80 long period variables in the wide range of period. No new sources are detected; all detected sources are variables with period longer than 300 days; no evidence is found that the dust grains in the outer envelope have influenced on this line. The time variation of this maser line for 7 stars, T Cep, ${\mu} Cep$, U Her, R Leo, R Lmi, U Ori, and R Ser is observed and compared with optical light curve at the same epoch of maser observation. No universial relation between the time variation and the optical light curve is found. It implies that the radiation from a central star does not much play an important role for the direct pumping of the SiO maser line.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.611-617
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• 2008

In ubiquitous environments, the content adaptable services can be dynamically provided to adapt the frequent changes of contexts. These services have common things that the kinds of context factors are limited to ubiquitous environment, though the contexts are flexible. To reuse service architecture can be reasonable for effective adaptable service. In this paper, we design a software architecture with product line techniques for content adaptable applications in ubiquitous environment. Description of product line is to define variation points and their variants, to find out the dependencies between them and to keep the model based architecture, their alternatives.

• Korean Journal of Mathematics
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• v.30 no.1
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• pp.53-60
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• 2022

Let R be a finite commutative ring with non zero identity. The unit graph of R denoted by G(R) is the graph obtained by setting all the elements of R to be the vertices of a graph and two distinct vertices x and y are adjacent if and only if x + y ∈ U(R), where U(R) denotes the set of units of R. In this paper, we find the commutative rings R for which G(R) is a line graph. Also, we find the rings for which the complements of unit graphs are line graphs.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.288-289
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• 2007

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.443-452
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• 1994

This study describes the effects of novel1, 25-dihydroxyvitamin D$_3$ analong[1,25(OH)$_2$-16ene-23yne-26, 27-F6-D$_3$] on proliferation of the human histiocytic lymphoma cell line U937 in vitro. We also examined the expression of c-myc oncogene in U937 cells was apparently inhibited to 62% and 87% of the control level after 4 days in the presence of 10-8M and 10-7 M of this analog, respectively. This compound morpholgically and functionally differentiated U937 cells to nonocyte-macrophage phenotype showing the increase of adherence ability to surface and a decrease of N/C ratio in Giemsa staining . Especially, nonspecific esterase activity which is a marker of cell differentiation to monocyte-macrophage was positive, and production of the positive stained cells increased in a dose dependent fashion . The expression of c-myc oncogene by 1, 25(OH)$_2$D$_3$ analog(10-7 M) was reduced by 60% at the mRNA level as determined by Northern blotting. The effects of this novel analog on cell proliferation and cell differentiation may open op new therapeutic strategies for human disorders such as psoriassis and may provide a tool to understand the mechanism of action of vitamin D$_3$ seco-steroids in malignancy.