• Title/Summary/Keyword: DC potential

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Analysis of DC Plasma using Electrostatic Probe and Fluid Simulation (정전 탐침법과 유체시뮬레이션을 이용한 DC플라즈마 특성 연구)

  • Son, Eui-Jeong;Kim, Dong-Hyun;Lee, Ho-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.10
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    • pp.1417-1422
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    • 2014
  • Using a parallel plate DC plasma system was prepared. Using this equipment, we investigated the basic discharge characteristics of DC argon plasma in terms of electron density, temperature, voltage and current waveforms and plasma potential. The effects of the electrode gap distance, input voltage, ballast resistance and pressure were measured using electrostatic probe. Plasma simulation using fluid approximation has been performed. External circuit effects was included in the simulation. Measured and calculated current voltage characteristics show similar tendencies.

An Economic Analysis of Potential Cost Savings from the Use of Low Voltage DC (LVDC) Distribution Network

  • Hur, Don;Baldick, Ross
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.812-819
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    • 2014
  • The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.

The Effect of External DC Electric Field on the Atmospheric Corrosion Behaviour of Zinc under a Thin Electrolyte Layer

  • Liang, Qinqin;YanYang, YanYang;Zhang, Junxi;Yuan, Xujie;Chen, Qimeng
    • Corrosion Science and Technology
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    • v.17 no.2
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    • pp.54-59
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    • 2018
  • The effect of external DC electric field on atmospheric corrosion behavior of zinc under a thin electrolyte layer (TEL) was investigated by measuring open circuit potential (OCP), cathodic polarization curve, and electrochemical impedance spectroscopy (EIS). Results of OCP vs. time curves indicated that the application of external DC electric field resulted in a negative shift of OCP of zinc. Results of cathodic polarization curves measurement and EIS measurement showed that the reduction current of oxygen increased while charge transfer resistance ($R_{ct}$) decreased under the external DC electric field. Variation of OCP negative shift, reduction current of oxygen, and $R_{ct}$ increase with increasing of external DC electric field strength as well as the effect of external DC electric field on double-layer structure in the electrode/electrolyte interface and ions distribution in thin electrolyte layer were analyzed. All results showed that the external DC electric field could accelerate the corrosion of zinc under a thin electrolyte layer.

Fabrication of the 7$\times$7 mm Planar Inductor for 1W DC-DC Converter (1W DC-DC 컨버터를 위한 7$\times$7 mm 평면 인덕터의 제조)

  • Bae, Seok;Ryu, Sung-Ryong;Kim, Choong-Sik;Nam, Seoung-Eui;Kim, Hyoung-June;Min, Bok-Ki;Song, Jae-Sung
    • Journal of the Korean Magnetics Society
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    • v.11 no.5
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    • pp.222-225
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    • 2001
  • The planar type inductors have a good potential for the application of miniaturized low power DC-DC converters. For those high quality application, the reduction of coil loss and also magnetic films which have good high frequency properties are required. Fabricated inductor was consisted of FeTaN/Ti magnetic film and electroplated Cu coil thickness of 100$\mu\textrm{m}$ and $SiO_2$ as a insulating layer. The inductor was designed double rectangular spiral shape for magnetic field highly confining within the device. The measured value of inductance and resistance were 980 nH and 1.7 $\Omega$ at 1 MHz as operating frequency of device. The Q factor is 3.55 at 1 MHz.

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Screening and Characterization of Pro biotic Lactic Acid Bacteria Isolated from Korean Fermented Foods

  • Lim, Sung-Mee;Im, Dong-Soon
    • Journal of Microbiology and Biotechnology
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    • v.19 no.2
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    • pp.178-186
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    • 2009
  • To examine their potential as probiotics, acid and bile tolerance, antibiotics resistance, adhesion capacity to Caco-2 and HT-29, and antibacterial activity, of LAB isolated from Korean fermented foods such. as dongchimi, kimchi, Meju, and doenjang were assayed against foodborne pathogenic bacteria. DC 55, DC 136, DC 222, KC 21, KC 24, KC 34, KC 43, KC 117, MJ 54, MJ 301, SP 33, and SP 170 strains were resistant to acid and bile conditions. In particular, DC 55, DC 136, KC 24, KC 43, and MJ 301 strains were highly resistant to higher than 20 ${\mu}g/ml$ concentrations of vancomycin, streptomycin sulfate, or amoxicillin, whereas, DC 222, KC 21, KC 34, KC 117, MJ 54, and SP 33 strains were susceptible to lower than 2 ${\mu}g/ml$ concentrations of those antibiotics. The adhesion to HT-29 and Caco-2 cells varied with the strains tested in a strain-dependent manner. The highest level of adhesion was observed with DC 55, KC 21, KC 24, and MJ 301 strains, having higher than 50% of adhesion to HT-29 or Caco-2 cells. In addition, Staphylococcus aureus was the most sensitive to KC 21, showing an inhibition of about 70%, and the antibacterial activity of KC 21 against S. aureus resulted most likely from both organic acids and bacteriocin. Based on its phenotypic characteristics and utilization of various sugars, the KC 21 strain was identified as Lactobacillus plantarum.

Inhibitory Activity of Sedum middendorffianum-Derived 4-Hydroxybenzoic Acid and Vanillic Acid on the Type III Secretion System of Pseudomonas syringae pv. tomato DC3000

  • Kang, Ji Eun;Jeon, Byeong Jun;Park, Min Young;Kim, Beom Seok
    • The Plant Pathology Journal
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    • v.36 no.6
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    • pp.608-617
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    • 2020
  • The type III secretion system (T3SS) is a key virulence determinant in the infection process of Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Pathogen constructs a type III apparatus to translocate effector proteins into host cells, which have various roles in pathogenesis. 4-Hydroxybenozic acid and vanillic acid were identified from root extract of Sedum middendorffianum to have inhibitory effect on promoter activity of hrpA gene encoding the structural protein of the T3SS apparatus. The phenolic acids at 2.5 mM significantly suppressed the expression of hopP1, hrpA, and hrpL in the hrp/hrc gene cluster without growth retardation of Pst DC3000. Auto-agglutination of Pst DC3000 cells, which is induced by T3SS, was impaired by the treatment of 4-hydroxybenzoic acid and vanillic acid. Additionally, 2.5 mM of each two phenolic acids attenuated disease symptoms including chlorosis surrounding bacterial specks on tomato leaves. Our results suggest that 4-hydroxybenzoic acid and vanillic acid are potential anti-virulence agents suppressing T3SS of Pst DC3000 for the control of bacterial diseases.

Simplified PWM Strategy for Neutral-Point-Clamped (NPC) Three-Level Converter

  • Ye, Zongbin;Xu, Yiming;Li, Fei;Deng, Xianming;Zhang, Yuanzheng
    • Journal of Power Electronics
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    • v.14 no.3
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    • pp.519-530
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    • 2014
  • A novel simplified pulse width modulation(PWM) strategy for neutral point clamped (NPC) three-level converter is proposed in this paper.The direct output voltage modulation is applied to reduce the calculation time. Based on this strategy, several optimized control methods are proposed. The neutral point potential balancing algorithm is discussed and a fine neutral point potential balancing scheme is introduced. Moreover, the minimum pulse width compensation and switching losses reduction can be easily achieved using this modulation strategy. This strategy also gains good results even with the unequal DC link capacitor. The modulation principle is studied in detail and the validity of this simplified PWM strategy is experimentally verified in this paper. The experiment results indicated that the proposed PWM strategy has excellent performance, and the neutral point potential can be balanced well with unequal DC link captaincies.

Diversity and Bioactive Potential of Culturable Fungal Endophytes of Medicinal Shrub Berberis aristata DC.: A First Report

  • Sharma, Supriya;Gupta, Suruchi;Dhar, Manoj K.;Kaul, Sanjana
    • Mycobiology
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    • v.46 no.4
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    • pp.370-381
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    • 2018
  • Bioactive natural compounds, isolated from fungal endophytes, play a promising role in the search for novel drugs. They are an inspiring source for researchers due to their enormous structural diversity and complexity. During the present study fungal endophytes were isolated from a well-known medicinal shrub, Berberis aristata DC. and were explored for their antagonistic and antioxidant potential. B. aristata, an important medicinal shrub with remarkable pharmacological properties, is native to Northern Himalayan region. A total of 131 endophytic fungal isolates belonging to eighteen species and nine genera were obtained from three hundred and thirty surface sterilized segments of different tissues of B. aristata. The isolated fungi were classified on the basis of morphological and molecular analysis. Diversity and species richness was found to be higher in leaf tissues as compared to root and stem. Antibacterial activity demonstrated that the crude ethyl acetate extract of 80% isolates exhibited significant results against one or more bacterial pathogens. Ethyl acetate extract of Alternaria macrospora was found to have potential antibacterial activity. Significant antioxidant activity was also found in crude ethyl acetate extracts of Alternaria alternata and Aspergillus flavus. Similarly, antagonistic activity of the fungal endophytes revealed that all antagonists possessed inhibition potential against more than one fungal pathogen. This study is an important step towards tapping endophytic fungal diversity for bioactive metabolites which could be a step forward towards development of novel therapeutic agents.

Anti-tumor Activity of Acanthospermum hispidum DC on Dalton Ascites Lymphoma in Mice

  • Rajendran, N.N.;Deepa, N.
    • Natural Product Sciences
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    • v.13 no.3
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    • pp.234-240
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    • 2007
  • The present study investigated the anti-tumor activity of ethyl acetate extract of Acanthospermum hispidum DC against daltons ascites lymphoma in mice. The extract was prepared by cold maceration with ethyl acetate for 3 - 7 days and evaporated in vacuum to dry. (Yield : 14.2 g, 1.42% w/w). The extract was fractionated by column chromatography by using gradient elution technique and the diterpenes fraction isolated (0.649 g). Both extract and the fraction were administered as oral suspension with tween 20 in water to tumor bearing mice (DAL) and changes in dead cell count, histopathology of tumor cells, hematological parameters and median survival time (MST) were examined and compared with that of tumor control or 5-Fluorouracil (5-FU). The results indicate that both ethyl acetate extract and fraction possess anti-tumor activity. The study suggests that Acanthospermum hispidum DC seems promising as a source of diterpenes for potential anti-tumor activity.

The Development of the Low Power Consumption and Long Life Battery using a Galvanic Series (저전력형 반영구적인 갈바니 전원장치 개발)

  • Bae, Jeong-Hyo;Kim, Dae-Kyeong;Ha, Tae-Hyun;Lee, Hyun-Goo;Choi, Sang-Bong;Jeong, Seong-Hwan
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.3201-3204
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    • 2000
  • In general, analog tester or strip chart recorder have been used to measure the corrosion potential of structures such as gas pipelines, oil pipelines, hot water pipelines, power cables etc. Recently, automatic digital data logger substitutes for these manual equipment because using these manual equipments are tedious and time consuming. However, digital data logger also has a shortcoming, that is, short measuring time because of the short lifetime of batteries. Therefore, we developed a long lifetime and low power loss battery taking advantage of galvanic series. In this paper, the results of development for power generator using two metals and DC/DC converter in order to obtain enough voltage for the operation of digital data logger. DC/DC converter operates with 0.5[V]. Its output voltage is 3.5[V] and output current is from 60[mAh] to 1,200[mAh].

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