• Journal of Power Electronics
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• v.16 no.4
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• pp.1316-1323
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• 2016

Multilevel inverters (MLIs) have been preferred over conventional two-level inverters due to their inherent properties such as reduced harmonic distortion, lower electromagnetic interference, minimal common mode voltage, ability to synthesize medium/high voltage from low voltage sources, etc. On the other hand, they suffer from an increased number of switching devices, complex gate pulse generation, etc. This paper develops an ingenious symmetrical MLI topology, which consumes lesser component count. The proposed level dependent sources concoction multilevel inverter (LDSCMLI) is basically a multilevel dc link MLI (MLDCMLI), which first synthesizes a stepped dc link voltage using a sources concoction module and then realizes the ac waveform through a conventional H-bridge. Seven level and eleven level versions of the proposed topology are simulated in MATLAB r2010b and prototypes are constructed to validate the performance. The proposed topology requires lesser components compared to recent component reduced MLI topologies and the classical topologies. In addition, it requires fewer carrier signals and gate driver circuits.

• Journal of the Korean Professional Engineers Association
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• v.33 no.4
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• pp.68-71
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• 2000

Tideland reclamation in Korea has significant meanings both in securing the staple food supply and in enlarging the limited land resources. Environmentally, that significantly contributes in protecting the sea and the tidelands connected to a reclaimed area from the direct exposure to the environmental destruction by filtering the large volume of contaminant discharged from the inland. Furthermore, within few years after closing a sea dike. formulation of new tideland begins in wide area in front. Therefore, tideland reclamation should not be the one that must be unconditionally objected. Instead, the methodology should be wisely redirected to minimize the environmental disorder. It will be one viable alternative to proceed the tideland reclamation at medium- to small-scales environment-friendly bringing minimal environmental change in the sea.

• Korean Journal of Microbiology
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• v.15 no.3
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• pp.131-138
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• 1977

The effects of various nitrogen soruces on the expression of nif gene were investigated using nif-lac fusants of Klebsiella pneumoniae. K. pneumoniae UK 2979 was infected with Mudl lysate prepared by heat induction of K. pneumoniae UK 4482. About 80 nif-lac fusants were greatly repressed. Amino acids, such as serine, glutamine and asparagine, were found to support the growth of K. pneumoniae M5al quite well, and showed a repressive effect on .betha.-galactosidase activities of nif-lac fusants LX-9 and LX-22 in NFHM. Glutamic acid, histidine and arginine rendered poor growth but high activities of .betha.-galactosidase. Good cell growth and high enzyme activity were observed when complex nitrogen sources, such as casitone, proteose pepone, were employed. .betha.-Galactosidase activities of LX-9 and LX-22 in nitrogen free minimal medium increased sharply within first 4 hours.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1656-1660
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• 2006

Distributed coordination function(DCF) is the primary random access mechanism of IEEE 802.11, which is the basic protocol of wireless LAN based on the CSMA/CA protocol. It enables fast installation with minimal management and maintenance costs and is a very robust protocol for the best effort service in wireless medium. The current DCF, however, is known to be unsuitable for real-time applications such as voice message transmission. In this paper, we focus on the performance issues of IEEE 802.11 which accommodate the prioritized messages. Existing results use the initial window size and backoff window-increasing factor as tools to handle the priority of the messages. Instead, we introduce a novel scheme which chooses the backoff timer with arbitrary probabilities. By this, one can greatly reduce the backoff delay of the lower priority messages without degrading the performance of higher priority.

• Journal of Pharmacopuncture
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• v.6 no.3
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• pp.87-90
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• 2003

The purpose of this study is to investigate and analyze the selection process of the Science Citation Index(SCI). SCI has been the benchmarking medium of scientific journals for over 40 years by reviewing thousands of journals published each year. The discipline of Traditional Oriental Medicine has been gaining global interest in recent years, yet the number of related journals indexed by SCI has been minimal. Korean Medicine has been producing number of quality journals for decades, but lack of journals in the English language and other problems has hindered consideration for registering with SCI. This paper will focus on the journal selection process at ISI and recommend the criteria needed for a journal to be considered for SCI selection.

• Microbiology and Biotechnology Letters
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• v.22 no.2
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• pp.158-163
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• 1994

Microorganisms capale of utilizing linear alkylbenzene sulfonates(LAS) as sole carbon source were isolated from industrial effluent by using LAS agar plates. The isolated strains were identified as Salmonella sp(BC-2) and Escherichia sp.(BC-3) from the results of morphological, cultural and biochemical tests. The optimal condition for the growth and biodegradation of LAS was the initial pH 7.0 and LAS concentration 0.1%. The isolated BC-2 and BC-3 strains harbored plasmid and LAS-degrading activity was lost when the plasmids were cured by mitomycin C. The plasmids were transformed into E. coli and transformants have the LAS-degrading activity. Isolated strains were examined for primary biodegradation rate of LAS in the medium by methylene blueactive substance(MBAS) method. Of these isolates, BC-2 and BC-3 strains degradated LAS upto 60% and high resistant to CdCl$_{2}$ and HgCl$_{2}$. Isolated strains were sensitive to chloramphenicol, kanamycin, rifampicin, streptomycin and tetracycline but resistant to ampicillin and lincomycin.] Its minimal inhibitory concentration(MIC) for ampicillin was more than 1500 $\mu $g/ml.

• YAKHAK HOEJI
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• v.53 no.3
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• pp.114-118
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• 2009

Bioemulsifiers are those chemicals which are produced from microorganisms but which have both hydrophilic and hydrophobic groups. $\alpha$-Glucosidase inhibitor ($\alpha$-GI) produced from Bacillus lentimorbus B-6 (B-6) showed bioemulsifying activity. But $\beta$-glucosidase inhibitor produced from B-6 didn't show emulsifying activity. $\alpha$-GI was purified from supernatant of B-6 grown in minimal culture medium containing glucose and sodium glutamate by Sephadex G-100 column chromatography and isolated from $\beta$-GI by dialysis against water. Toluene was determined as the best substrate for emulsifying activity of $\alpha$-GI. $\alpha$-GI showed thermostability at $100^{\circ}C$ for 15 min, high salt tolerance up to 32% NaCl and wide range of pH-stability at pH $4\sim10$. Emulsifying character of $\alpha$-GI can be useful for the liposome formation for the treatment of diabetes mellitus.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1549-1552
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• 2007

The cytoplasmic domain of syndecan-4, a type I transmembrane heparan sulfate proteoglycan, was overexpressed as a fused form with the ubiquitin molecule in Escherichia coli, and the fusion protein was purified using immobilized metal affinity chromatography (IMAC). The cytoplasmic domain was released from its fusion partner by using yeast ubiquitin hydrolase (YUH), and subsequently purified by reverse phase chromatography. The integrity of the resulting peptide fragment was checked by MALDI-TOF and NMR spectroscopy. The yield of the peptide was 3.0-1.5 mg per liter in LB or minimal medium, respectively. The recombinant expression and purification of this domain will enable us its structural and functional studies using multidimensional NMR spectroscopy.

• Korean Journal of Microbiology
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• v.18 no.3
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• pp.133-147
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• 1980

Washed mycelia of Aspergillus nidulans FGSC159 were incubated in CMC minimal liquid medium and the culture filtrate which contained induced extracellular cellulase was fractionated by a three-step procedure including chromatography on Bio-Gel P-150, chromatography on DEAE-Sephadex A-50 and chromatography on Sephadex G-100. Three CMCase components ; F-I-Ia, F-I-Ib and F-II-Ia were prepared. No enzyme activity toward avicel could be detected in these components. Similarly, there was no ${\beta}-glucosidase$ activity. pH-optima of the three components were all 5.0 in acetate buffer. Temperature-optima for the activities of F-I-Ia, F-Ib and F-II-Ia were $45^{\circ}C,\;40^{\circ}C\;and\;50^{\circ}C$, respectively. F-II-Ia was shown to be more thermostable than the other two components. F-II-Ia was proved to have quite a different substrate specificity and action property and action property from those of F-I-Ia and F-I-Ib by product analysis on liquid chromatography.

• KSBB Journal
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• v.15 no.6
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• pp.589-593
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• 2000

Several bacterial strains growing on benzene minimal medium were isolated from soil by enrichment culture, Burkholderia sp. SKK381 was identified and selected. In order to determine the ability of Burkholderia sp. SKK381 to degrade benzene. Changes in substrate concentration, cell growth, and pH were monitored from start-up in bath culture. At 30$^{\circ}C$, 1000 ppm of benzene was degraded 100% within 28hours. Cell growth conditions were best at an initial pH of 7.0 and a benzene concentration of 1000 ppm at 30$^{\circ}C$.