• The Plant Pathology Journal
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• v.18 no.1
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• pp.18-22
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• 2002

Two peptaibol antibiotics, peptavirins A and B, which exhibited strong inhibitory effect against Tobacco mosaic vials (TMV) infection, were isolated from steam-cooked rice culture of Apiocrea sp.14T. The peptavirins were identified as new derivatives of chrysospermins, which are 19-mer and have been reported to be produced in a fungal isolate. The physicochemical properties of the peptavirins were mostly identical with chrysospermins A through D except for the UV absorption spectrum. The peptavirins inhibited the growths of the Grampositive bacteria tested, including the plant pathogenic bacterium, Corynebacterium lilium, and the fungus, Aspergillus niger. Peptavirin A was somewhat cytotoxic to cancer cell lines, especially K562 (leukemia) and UACC 62 (melanoma), whereas peptavirin B only exhibited slight cytotoxicity.

• Journal of Life Science
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• v.27 no.6
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• pp.688-693
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• 2017

Antifungal bacterium against Colletotrichum coccodes causing black dot disease of potatoes and anthracnose of tomatoes was isolated from sewage sludge. The isolate showed a 99% sequence homology of partial 16S rRNA of Bacillus methylotrophicus CBMB205 and Bacillus amyloliquefaciens subsp. plantarum FZB42. The isolate was identified as Bacillus sp. SW29-2, using the neighbor-joining phylogenetic tree, BlastN sequence analysis, and morphological and cultural characteristics. Bacillus sp. SW29-2 is an aerobic, Gram-positive, endospore-forming bacterium, of which the morphological and physiological characteristics were the same as those of type strain B. lichniformis CBMB205, except for the cell growth of over 4% NaCl. The cell growth of the temperature and the initial pH of the medium was shown at $18-47^{\circ}C$ (opt. ca. $38^{\circ}C$) and 3-9 (opt. ca. 6.0), respectively. The inhibition size (diameter) of Bacillus sp. SW29-2 against four strains of C. coccodes ranged from 23 to 29 mm. Also, the isolate showed antifungal activity against penicillium rot-causing Penicillium expansum in apples. Thus far, any report on the antifungal activity of Baciilus spp. against C. coccodes has not been found. These results suggest that the Bacillus sp. SW29-2 isolate could be used as a possible biocontrol agent against C. coccodes, and further applied to other plant pathogenic fungi.

• Journal of fish pathology
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• v.27 no.2
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• pp.107-114
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• 2014

For the treatments and protection of bacterial fish disease, many requirements are needed for aquatic probiotics so that they are effective in aquaculture animals but are also harmless to humans. In the present study, among 17 candidate probiotic bacteria (CPB) obtained from the edible part of the shellfish, Bacillus sp. CPB-St (CPB-St) were selected and in vitro evaluated for the possibility as a probiotic strain for the control of fish streptococcosis which frequently occurs in the olive flounder farms. CPB-St showed inhibitory effects on the growth of various fish pathogenic bacteria, Streptococcus sp., S. parauberis, S. iniae, Lactococcus garvieae and L. piscium by the double layer test ranging about 18~26 mm of clear zone. Inhibitory activity of CPB-St to Streptococcus sp. was observed 6 hours after and the growth of Streptococcus sp. was decreased to 8~55 folds in the co-culture of CPB-St with Streptococcus sp.. The safety of CPB-St to fish and survival of CPB-St in the intestine were assessed in the olive flounder, Paralichthys olivaceus. Fish mortality was not observed in artificial infection with CPB-St for 2 weeks. CPB-St was entirely excreted from the stomach and intestine 24 hours after oral injection. This results indicate that CPB-St has potential applications as a probiotic for the control of fish streptococcosis in aquaculture.

• Korean Journal of Environment and Ecology
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• v.29 no.6
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• pp.884-894
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• 2015

To examine the relationship between microphytobenthos biomass and the condition index of Ruditapes philippinarum (manila clam), field observations were conducted seasonally at the tidal flats of Jeongsanpo and Hwangdo, Taean, Korea from February to November, 2012. A total of 122 species of microphytobenthos were identified over the study period with 85 species (30-45 species in season) at Jeongsanpo and 92 species (32-57 species) at Hwangdo. Chlorophyll a concentrations and cell number of microphytobenthos were $79.75mg/m^2$ and $3,255cells/cm^2$ at Jeongsanpo, and $151.50mg/m^2$ and $15,943cells/cm^2$ at Hwangdo, respectively. The dominant species were slightly different: Cylindrotheca closterium, Fallacia forcipata, Fogedia sp., Gyrosigma sp., and Navicula sp. at Jeongsanpo and C. closterium, Detonula pumila, Diploneis sp., Navicula sp. and Merismopedia sp. at Hwangdo tidal flat. Paralia sulcata was the representative species based on cell number at the two study sites. The number of microphytobenthos identified from the digestive organs of manila clams seasonally varied from 18 to 31 species at Jeongsanpo and dominant genus were Amphora, Navicula, Nitzschia and Paralia sulcata. At Hwangdo, the species number of microphytobenthos found in the digestive organs of manila clams were in the range of between 19 and 25 species in season and the dominant genus were Actinocyclus, Amphora, Coscinodiscus, Diploneis, Gyrosigma, Navicula, and Diploneis. The condition index of manila clams were greater at Hwangdo (0.57) than at Jeongsanpo (0.42). Present results could support that the condition index of manila clams is positively correlated with the species richness and chlorophyll a contents of microphytobenthos.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.312-321
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• 2013

In this paper, high efficiency control method for flyback inverter with synchronous rectifier(SR) based on photovoltaic AC modules is proposed. In this control method, the operation of SR is classified according to the voltage spike across main switch SP. When the voltage spike across SP is lower than the rating voltage of SP, the operation of active clamp circuit is interrupted for reducing the switching loss of auxiliary switch. In this time, the SR is operated for soft-switching of SP. When the voltage spike across Sp is higher than the rating voltage of SP, the operation of active circuit is activated for reducing the voltage spike. The SR is operated for reducing the conduction loss of secondary output diode. Thus, a switching loss of the main switch can be reduced in low power region, and weighted-efficiency can be improved. A theoretical analysis and the design principle of the proposed method are provided. And validity is confirmed through simulation and experimental results.

• Journal of Broadcast Engineering
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• v.18 no.3
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• pp.455-462
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• 2013

This paper introduces the Spatially Preprocessed Speech Distortion Weighted Multi-channel Wiener Filter (SP-SDW-MWF) for multi-microphone noise reduction and proposes a method to determine the speech distortion weights. The SP-SDW-MWF is known as a robust noise reduction algorithm against the error caused by the mismatch in microphones. The SP-SDW-MWF adopts weights which determine the amount of noise reduction at the expense of introducing speech distortion in the noise-suppressed speech. In this paper, we use the error of power spectral density between the estimated signal and the desired signal as the evaluation measure. Thus the a priori SNR is used to control the speech distortion weights in the frequency domain. In the experimental results, the proposed method yields better result in terms of MFCC distortion compared to the conventional method.

• Parasites, Hosts and Diseases
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• v.30 no.4
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• pp.263-268
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• 1992

A study was presented on the anisakid larvae in Astroconger myriaster which were caught at the Southern Sea and waled at Pusan area. The nematodes were morphologically classified into Anisakis sp. and Centracgecum sp. after fixation in 70% ethanol and clearing in lactophenol. Total of 1, 768 larval anisakids were collected from 259(67.8% positive rate) out of 382 examined A. myriaster. Total 642 larvae of Anisakis sp. were obtained from 94 (24.6%) and 1, 126 Ccntracaecum sp. were recovered from 165 (43.1%) fish. The average number of worms per infected fish was 4.6. The infection rate increased according to the length of fish, and all of the fish over 71 cm were found infected. The numbers (proportions) of recovered worms by the organs were 1, 440 (80.5%) in the omentuin, 166(9.4%) in the intestine, 107(6.0%) in the stomach, 32(1.8%) in the skin, 18(1.0%) in the muscle, 13(0.7%) in the liver, and 2(0.1%) in the head. The larvae in the muscle may infect the humans who are enjoying raw sliced meat of the fish.

• Microbiology and Biotechnology Letters
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• v.36 no.2
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• pp.165-172
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• 2008

To find the optimum growth and metal removal condition of isolated strain LH2, effects of the environmental factors such as medium pH, growth temperature, and metal concentrations were investigated. Based on the 18S rDNA analysis, the isolated strain was identified to Exophiala sp. with 100% homology. Isolated strain Exophiala sp. LH2 showed maximum removal efficiency of metals at the shaking conditions of pH 7 and $25^{\circ}C$. When the concentration of metal was under 200ppm, the specific metal removal velocity at pH 7 increased from 0.01 to 4.43 mg-metal $L^{-1}{\cdot}d^{-1}{\cdot}mg{\cdot}DCW^{-1}$ as the concentration of metal increased from 10 ppm to 200 ppm. When 200 ppm of each metal was contained in the culture medium adjusted with pH 7, metal removal efficiencies Cr, Cu, Ni, Pb and Zn were 99.28%, 97.67%, 91.94%, 99.77%, 99.61%, respectively.

• Korean Journal of Organic Agriculture
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• v.14 no.2
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• pp.219-228
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• 2006

This study was conducted to examine the distribution of arbuscular mycorrhizal fungi (AMF) in the soil grown tomato plants in Damyang districts. We collected twenty one soil samples from the rhizosphere of tomato plants which were grown under structure. Number of spores/g in the soil sized over $500{\mu}m,\;355{\sim}500{\mu}m,\;251{\sim}354{\mu}m,\;107{\sim}250{\mu}m\;and\;45{\sim}106{\mu}m$ were 0.01, 0.02, 0.09, 0.9, and 2.0. Total number of spores/g in the fresh soil were 3.02. Mycorrhizal root infection by vesicles, hyphae and arbuscules were 18.0%, 6.0% and 2.0%. To identify the genus of arbuscular mycorrhizal fungi, isolated mycorrhizal spores from the soil grown tomato plants were inoculated into the host plant of sudangrass and mass propagated for 4 months. As a result of identification, mycorrhizal spores were identified as Glomus sp., Gigaspora sp. and Acaulospora sp.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.56-65
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• 2007

The effect of gain dispersion on the self-pulsation (SP) characteristics due to the mode beating of two modes emitted in a multisection DFB laser composed of two complex-coupled DFB sections and a phase control section is investigated. When the peak wavelength, ${\lambda}_{p}$, of the gain spectrum of the DFB section is positioned in the center of the lasing wavelengths or the Bragg wavelengths of the two DFB sections, the maximum SP frequencies are higher and the modulation index has better characteristics compared to those cases for ${\lambda}_{p}$ fixed at the lasing wavelength or Bragg wavelength of one DFB section, when the difference between the Bragg wavelengths of the two DFB sections, ${\Dalta}{\lambda}_{B}$, is varied. When ${\lambda}_{p}$ is positioned in the renter of the Bragg wavelengths of the two DFB sections, the maximum SP frequency is higher and of the modulation index has better characteristics compared to those of the case for ${\lambda}_{p}$ positioned in the center of the lasing wavelengths of the two DFB sections.