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BER Performance of the OFDM System with One-Tap Equalizer Bank under the Two-ray Multipath Channel with Frequency Offset (주파수 오프셋을 갖는 이중 경로 상에서의 One-Tap 등화기 뱅크를 갖는 OFDM 시스템의 BER 성능)

  • Hongku Kang;Wooncheol Hwang;Kim, Kiseon
    • Proceedings of the IEEK Conference
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    • pp.51-54
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    • 1999
  • It is well known that the OFDM transmission is weak against the frequency offset. We evaluate the BER performance of the OFDM system with guard interval and simple one-tap equalizer bank. For the small frequency offset, the loss in $E_{b}$ $N_{o}$ is about 1㏈ at required BER = 10$^{-5}$ , when the mean value of the second-ray's attenuation coefficient is 0.25 and the normalized frequency offset, which is normalized about OFDM symbol time, is 5%.%.%.

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A Protection Algorithm of 23kV Shunt Capacitor Banks (23kV급 Capacitor Bank 보호 알고리즘)

  • Lim J.U;Kwon Y.J;Kang S.H.
    • Proceedings of the KIEE Conference
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    • pp.443-445
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    • 2004
  • 본 논문에서는 22.9kV급 Shunt Capacitor Bank 내부 고장으로 인한 불평형 요소를 검출하기 위하여 기존의 차동전압의 크기만을 이용한 보호 방식을 검토하고, 이 보호 방식에서 발생되는 여러 문제점들을 해결하기 위한 개선 방안을 제안한다. 기존의 차동전압의 크기를 이용한 보호 방식에서는 인입단 근처에서의 고저항 아크 고장이나 접지단 근처에서의 지락 고장 등에 의해 Capacitor 소자에 손상을 입을 수 있지만, 이에 대한 고장 판정이 용이하지 않다. 따라서 이를 해결하기 위하여 본 논문에서는 차동전압의 주파수 계전 방식 및 접지단 전압 등을 도입하였다. 특히, 주파수 계전 요소를 도입할 경우에 비선형 부하 둥으로부터 발생되는 고조파의 영향이 없다는 것을 입증하여 부하의 종류와는 무관하게 본 논문에서 제안한 방법이 적용될 수 있음을 보였다 본 논문에서 제안한 알고리즘은 사례 연구를 통하여 그 타당성이 입증되었다.

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A Feasibility study on Removal Characteristics of Taste and Odor using Bank Filtration Treatment (강변여과에 의한 이.취미 물질 제어 특성에 관한 타당성 연구)

  • Maeng, Sung-Kyu;Park, No-Suk;Lim, Jae-Lim;Kim, Seong-Su;Jeong, Woo-Chang
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.3
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    • pp.307-317
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    • 2010
  • This study was conducted in order to investigate bulk organic matter characteristics and behavior of geosmin and 2-methylisoborneol (2-MIB) during riverbank filtration, which are general surrogates of taste and odor in drinking water. Column studies were used to simulate bank filtration systems. Most of the aliphatic organic matter was removed effectively after soil passage, and it is believed to be polysaccharides according to LC-OCD and F-EEM analysises. Removal efficiencies of geosmin and 2-MIB within the filtration column reached above 95%. It was found that the removal of total dissolved organic matter has a correlation with that of geosmin and 2-MIB in the near of filtration surface (about 50cm).

Enzymatic Activities of Allergen Extracts from Three Species of Dust Mites and Cockroaches Commonly Found in Korean Home

  • Jeong, Kyoung-Yong;Kim, Chung-Ryul;Yong, Tai-Soon
    • The Korean Journal of Parasitology
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    • v.48 no.2
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    • pp.151-155
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    • 2010
  • Allergen extracts from dust mites and cockroaches commonly found in Korean homes were used to evaluate their enzymatic activity as they are believed to influence allergenicity. Allergen extracts were prepared from 3 dust mite species (Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae) and 3 cockroach species (Blattella germanica, Periplaneta americana, and P. fuliginosa) maintained in the Korea National Arthropods of Medical Importance Resource Bank. Proteins were extracted in PBS after homogenization using liquid nitrogen. The activities of various enzymes were investigated using the API Zym system. No significant difference in phosphatase, lipase, or glycosidase activity was observed among the 6 allergen extracts, but much difference was observed in protease activity. Protease activity was assessed in more detail by gelatin zymography and the EnzChek assay. Extract from T. putrescentiae showed the highest protease activity, followed by those of the cockroach extracts. Extracts from D. farinae and D. pteronyssinus showed only weak protease activity. Gelatinolytic activity was detected mainly in a 30-kDa protein in D. farinae, a 28-kDa protein in D. pteronyssinus, a > 26-kDa protein in T. putrescentiae, a > 20-kDa protein in B. germanica, and a > 23-kDa protein in P. americana and P. fuliginosa. The information on various enzymatic activities obtained in this study may be useful for future studies. In particular, the strong protease activity found in cockroach extracts could contribute to sensitization to cockroach allergens, which is known to be associated with the development of asthma.

Isolation and Characterization of Pathogenesis-Related Protein 5 (PgPR5) Gene from Panax ginseng

  • Kim, Yu-Jin;Lee, Jung-Hye;Jung, Dae-Young;Sathiyaraj, Gayathri;Shim, Ju-Sun;In, Jun-Gyo;Yang, Deok-Chun
    • The Plant Pathology Journal
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    • v.25 no.4
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    • pp.400-407
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    • 2009
  • A pathogenesis-related protein (PgPR5) gene that isolated from the leaf of Panax ginseng was characterized. The ORF is 756 bp with a deduced amino acid sequence of 251 residues. The calculated molecular mass of the matured protein is approximately 27.5 kDa with a predicated isoelectric point of 7.80. A GenBank BlastX search revealed that the deduced amino acid of PgPR5 shares highest sequence similarity to PR5 of Actinidia deliciosa (80% identity, 87% similarity). PgPR5 has a C-terminal and N-terminal signal peptide, suggesting that it is a vacuolar secreted protein. The expression of PgPR5 under various environmental stresses was analyzed at different time points using real-time PCR. Our results reveal that PgPR5 is induced by salt stress, chilling stress, heavy metal, UV, and pathogen infection. These results suggest that the PgPR5 could play a role in the molecular defence response of ginseng to abiotic and pathogen attack. This is the first report of the isolation of PR5 gene from the P. ginseng.

Development of the Crowbar System Using a Vacuum Switch (진공 스위치를 이용한 Crowbar 시스템의 개발)

  • 이태호;허창수;이홍식
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.12
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    • pp.584-590
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    • 2002
  • Crowbar system is usually applied to a pulsed power system in which a capacitor bank is discharged into a load. This provides a free wheeling path for the load current and prevents the capacitor from recharging due to a reverse voltage. Usually diodes have been used as a crowbar switch, but it is not a practical system because the cost of the diodes goes up enormously with increasing the system voltage and current. This paper presents a novel protection scheme of a charging and discharging system of a 300 kJ capacitor bank using a low-cost crowbar system which consists of a crowbar switch and resistors. Triggered vacuum switch(TVS) was used for a crowbar switch, and Rogowski coil was used to determine a trigger time of TVS. When this crowbar system is applied to our pulsed power system which consists of capacitor bank($123muF$), inductor() for forming a pulse, load resistor$(100 m\Omega)$, and a closing switch, instantaneous reversal voltage of capacitor bank could be limited less than 1.8 ㎸ until capacitor bank was charred to 17 ㎸.

Enzymatic Transformation of Ginsenoside Rb1 by Lactobacillus pentosus Strain 6105 from Kimchi

  • Kim, Se-Hwa;Min, Jin-Woo;Quan, Lin-Hu;Lee, Sung-Young;Yang, Dong-Uk;Yang, Deok-Chun
    • Journal of Ginseng Research
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    • v.36 no.3
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    • pp.291-297
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    • 2012
  • Ginsenoside (ginseng saponin), the principal component of ginseng, is responsible for the pharmacological and biological activities of ginseng. We isolated lactic acid bacteria from Kimchi using esculin agar, to produce ${\beta}$-glucosidase. We focused on the bio-transformation of ginsenoside. Phylogenetic analysis was performed by comparing the 16S rRNA sequences. We identified the strain as Lactobacillus (strain 6105). In order to determine the optimal conditions for enzyme activity, the crude enzyme was incubated with 1 mM ginsenoside Rb1 to catalyse the reaction. A carbon substrate, such as cellobiose, lactose, and sucrose, resulted in the highest yields of ${\beta}$-glucosidase activity. Biotransformations of ginsenoside Rb1 were analyzed using TLC and HPLC. Our results confirmed that the microbial enzyme of strain 6105 significantly transformed ginsenoside as follows: Rb1${\rightarrow}$gypenoside XVII, Rd${\rightarrow}$F2 into compound K. Our results indicate that this is the best possible way to obtain specific ginsenosides using microbial enzymes from 6105 culture.

Design and Operational Characteristics of 150MW Pulse Power System for High Current Pulse Forming Network (대전류 펄스 성형이 가능한 150MW급 펄스파워 시스템의 설계 및 동작특성)

  • Hwang, Sun-Mook;Kwon, Hae-Ok;Kim, Jong-Seo;Kim, Kwang-Sik
    • Journal of IKEEE
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    • v.16 no.3
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    • pp.217-223
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    • 2012
  • This paper presents design and operational characteristics of 150 MW pulse power system for high current pulse forming network to control trigger time. The system is composed of two capacitor bank modules. Each capacitor bank module consist of a trigger vacuum switch, 9k 33kJ capacitor, an energy dump circuit, a crowbar circuit and a pulse shaping inductor and is connected in parallel. It is controlled by trigger controller to select operational module and determine triggering time. Pspice simulation was conducted about determining parameters of components such as crowbar circuit, capacitor, pulse forming inductor, trigger vacuum switch and predicting results of experiment circuit. The result of the experiment was in good agreement with the result of the simulation. The various current shapes with 300~650 us pulse width is formed by sequential firing time control of capacitor bank module. The maximum current is about 40 kA during simultaneous triggering of two capacitor bank modules. The developed 150 MW pulse power system can be applied to high current pulse power system such as rock fragmentation power sources, Rail gun, Coil gun, nano-powers, high power microwave.

Microwave Dielectric Properties of Bi2O3-TiO2 Composite Ceramics

  • Axelsson, Anna-karin;Sebastian, Maladil;McN Alford, Neil
    • Journal of the Korean Ceramic Society
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    • v.40 no.4
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    • pp.340-345
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    • 2003
  • B $i_2$ $O_3$-Ti $O_2$ composite dielectric ceramics have been prepared by a conventional solid state ceramic route. The composite ceramics were prepared with starting materials of different origin and the microwave dielectric properties were investigated. The sintered ceramics were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, Raman and microwave methods. Structural and microstructural analyses identified two separate phases: Ti $O_2$(rutile) and B $i_2$ $Ti_4$0$_{11}$. The separate grains of titania and bismuth titanate were distributed uniformly in the ceramic matrix. The composition 0.88Ti $O_2$-0.12B $i_2$ $Ti_4$ $O_{11}$ was found to have a Q$\times$f of 9300 GHz (measured at a frequency of 3.9 GHz), a temperature coefficient of frequency, $\tau$$_{cf}$ near zero and a high relative permittivity, $\varepsilon$r of 83. The microwave dielectric properties were measured down to 20$^{\circ}$K K. The quality factor increased on cooling the ceramic samples.les.

Conservation of the Epothilone-Biosynthetic Genes in Sorangium cellulosum Strains (Sorangium cellulosum 균주들의 에포틸론 생합성 유전자 보존)

  • Hyun, Hye-Sook;Youn, Jin-Kwon;Cho, Kung-Yun
    • Korean Journal of Microbiology
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    • v.47 no.2
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    • pp.170-173
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    • 2011
  • The epothilone biosynthetic gene cluster (epoA~F, epoK) of Sorangium cellulosum KYC3013, an epothilone producing myxobacterium isolated in Korea, was cloned. When the amino acid sequences of the encoded proteins were compared with those from S. cellulosum SMP44, S. cellulosum So ce90, and S. cellulosum So0157-2, which were isolated in other continents or country, the proteins from different strains were 97.4-99.8% identical each other. This suggested that the epothilone-biosynthetic gene clusters are well conserved in S. cellulosum strains.