• Mycobiology
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• v.39 no.4
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• pp.278-282
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• 2011

The objective of this study was to find useful fungi with ${\alpha}$-amylase activity from the Korean traditional nuruk for the quality of traditional Korean alcoholic beverage. In this study, 165 samples of traditional nuruk were collected from 170 regions throughout Korea and the fungi were isolated to a total of 384 strains. In order to investigate the effect of microflora on nuruk, ${\alpha}$-amylase activity, saccharogenic power (SP), starch hydrolysis activity and acid producing activity were evaluated. Ten strains were selected by ${\alpha}$-amylase activity, which ranged from 458.47 to 1,202.75 U/g. The size of the discolored zone for the starch hydrolysis activity of each fungus ranged from 0.3 to 2 cm. The SP of the 10 strains ranged from 228.8 to 433.4 SP. Of the 10 stains, three were identified as Aspergillus oryzae, two as Aspergillus flavus, two as Lichtheimia sp., one as Rhizopus oryzae and two as other strains. The total aflatoxins present in the nuruks were examined using enzyme-linked immunosorbent assay. The 10 nuruks had less than 1.11 ppb of aflatoxins.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.829-832
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• 2014

This study was conducted to investigate antioxidative and physiological activities of ethanol extracts concentration from Monascus-Fermented Chinese Yam (MFCY). The ethanol extracts from MFCY were measured to examine pigments, DPPH radical scavenging activity, reducing power and monacolin K contents. As a results show that Monascus sp. MK805, with Dioscorea japonica as the substrate can produce pigments (yellow, orange and red), DPPH radical scavenging activity, reducing power and monacolin K content at 29.6 (yellow), 15.1 (orange), 20.4 (red), 72.8%, 1.74(OD at 700nm), 480.6 mg/kg in EtOH extract, respectively. Therefore, fermented chinese yam (Dioscorea japonica) was estimated to be effective biological activity material.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.584-597
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• 2011

In this paper, low-loss and high-power RF SP6T switch chips are designed, fabricated and measured for GSM/EGSM/DCS/PCS applications using WIN Semiconductors 0.5 ${\mu}m$ pHEMT process. We utilized a combined configuration of series and series-shunt structures for optimized switch performance, and a common transistor structure on a receiver path for reducing chip area. The gate width and the number of stacked transistors are determined using ON/OFF input power level of the transceiver system. To improve the switch performance, feed-forward capacitors, shunt capacitors and parasitic FET inductance elimination due to resonance are actively used. The fabricated chip size is $1.2{\times}1.5\;mm^2$. S-parameter measurement shows an insertion loss of 0.5~1.2 dB and isolation of 28~36 dB. The fabricated SP6T switch chips can handle 4 W input power and suppress second and third harmonics by more than 75 dBc.

• Journal of Korean Society on Water Environment
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• v.39 no.3
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• pp.223-230
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• 2023

Harmful algae blooms have become a serious environmental problem in major river basins in Korea. They are known to produce various algal organic matters (AOMs) including intracellular organic matters (IOMs) and extracellular organic matters (EOMs). Generally AOMs cannot be easily removed by coagulation/flocculation process in conventional drinking water plants. AOMs produced by blue-green algae also include various toxins such as Microcystins, Anatoxin-a, and Saxitoxin known to have harmful effects on living organisms in aquatic environment. In this study, toxic effects of EOMs produced by three different algae species (Microcystis sp., Anabaena sp., and Oscillatoria sp.) on zebrafish were investigated using electroencephalography (EEG) recording method, a technology for recording brain activity. Electroencephalographic changes in zebrafish revealed that a low EOM had a negative effect on zebrafish compared to both Anabaena sp. and Oscillatoria sp. at 30 ppm EOM exposures. This result might be due to Microcystins present in EOMs produced by Microcystis sp. As a result of power spectrum density anallysis, exposure to EOMs produced by Microcystis sp. caused a state of vigilance in zebrafish. This EEG based toxicity test can be used to examine effects of harmful materials at low levels on living organisms in an aquatic system.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.720-721
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• 2011

본 논문에서는 제주 스마트그리드실증단지에서 진행중인 스마트그리드 5개 프로젝트 중 송배전분야의 전력망을 통합 운영하는 Smart Power Grid(SPG) 실증시스템의 설계와 구축 현황에 대해서 기술한다. 스마트그리드 프로젝트는 SPG외에도 ST(Smart Transportation), SP(Smart Place), SR(Smart Renewable), SES(mart Electric Service)가 있는데, SPG는 SES 프로젝트에서 운영하는 통합관제센터(TOC)를 거쳐 ST, SR, SP 시스템들과 운전 정보를 서로 교환하여 사용한다.

• The Plant Pathology Journal
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• v.34 no.4
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• pp.335-340
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• 2018

To investigate the difference in the disinfectant efficiency of ozone microbubbles ($O_3MB$) and ozone millibubbles ($O_3MMB$), the morphological change of the treated Fusarium oxysporum f. sp. melonis spores was observed with scanning and transmission electron microscopies (SEM and TEM). The disinfectant efficiency of $O_3MB$ on F. oxysporum f. sp. melonis spores was greater than that of $O_3MMB$. On observation with SEM, it was revealed that morphological change of F. oxysporum f. sp. melonis spores was caused by $O_3MB$ and $O_3MMB$, and damage to the spore surfaces by $O_3MB$ occurred sooner than that by $O_3MMB$. On observation with TEM, it was furthermore confirmed that F. oxysporum f. sp. melonis spores treated with $O_3MB$ induced wavy deformation of cell membrane and the intracellular change different from that with $O_3MMB$. Therefore, the greater disinfection efficiency of $O_3MB$ was suggested to be caused due to the function of the MB in addition to the oxidative power of $O_3$.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.406-411
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• 2001

In a bacterial denitrification test with Pseudomonas sp. and anaerobic consortium, more nitrates and less substrate were consumed but less metabolic nitrite was produced under an anaerobic $H_2$ condition rather than under $N_2$ condition. In a bioelectrochemical denitrification test with the same organisms, the electrochemically reduced neutral red was confirmed to be a substitute electron donor and a reducing power like $H_2$. The biocatalytic activity of membrane-free bacterial extract, membrane fraction, and intact cell for bioelectrochemical denitrification was measured using cyclic voltammetry. When neutral red was used as an electron mediator, the electron transfer from electrode to electron acceptor (nitrate) via neutral red was not observed in the cyclic voltammogram with the membrane-free bacterial extract, but it was confirmed to gradually increase in proportion to the concentration of nitrate in that of the membrane fraction and the intact cell of Pseudomonas sp.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1211-1214
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• 2003

The film is prepared by electron cyclotron resonance chemical vapor deposition (ECRCVD) employing CH$_4$ and H$_2$ gases. It is deposited by the control of microwave plasma power, gas flow ratio, deposition pressure, and In-situ thermal treatment temperature. The structure of a-C:H (hydrogenated amorphous carbon) thin film is analysed by FT-IR spectroscopy. The fraction sp$^3$ versus sp$^2$ bonding is very important to clear up the surface and interrace of a-C:H film properties such as nano-scale friction behavior. The sp$^3$ versus sp$^2$ bonding of a-C:H thin film is dependent on the deposition conditions, therefore. nano-scale friction behavior is dependent on the deposition conditions.

• Journal of Life Science
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• v.21 no.1
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• pp.81-88
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• 2011

Biological activities (${\alpha},{\alpha}'$-diphenyl-${\beta}$-picrylhydrazyl (DPPH) free radical scavenging activity, fibrinolytic activity and reducing power) and biochemical properties (protein content and electrophoretical protein patterns) were examined in solid state fermentation with Bacillus subtilis and Aspergillus kawachii using silkworm powder (SP) as substrate. The highest protein contents and free radical scavenging activities were seen in the SP fermented for 12 days with B. subtilis and A. kawachii, and these were in a time-dependent manner. The highest reducing power was seen in the SP fermented for 6 days with B. subtilis and for 12 days with A. kawachii, respectively. The highest fibrinolytic activities were seen in silkworm fermented for 6 days with B. subtilis and A. kawachii, but this activity was higher in the A. kawachii fermented SP than that of B. subtilis. When total protein patterns were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE), the proteins of the SP fermented with B. subtilis for 3 days were completely degraded, while the protein degradation in the SP fermented with A. kawachii occurred after 12 days and this degradation increased proportionally to culture time. As a result, the SP fermented with both B. subtilis and A. kawachii showed higher fibrinolytic activities after 6 days of fermentation and antioxidative activity after 12 days, indicating that physiological activities of the fermented SP using these strains were highly improved compared to the unfermented SP, and that this compound could be a candidate material as a dietary supplement of healthy functional foods.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.105-110
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• 2001

It has recently been raised main issue how solve the problem of insufficient energy. One of the solution is to increase the thermal efficiency of power generation system. For the purpose of high efficiency, it is necessary to increase the steam temperature and pressure. So, the use of modified $9{\sim}12%Cr$ steel having superior creep rupture strength and oxidation resistance is required to endure such severe environment. The evaluation of creep properties of those heat resistance material is very important to secure the reliability of high temperature and pressure structural components. Since creep properties are determined by microstructural change such as carbide precipitation and coarsening, It is certain that there are some relationship between creep properties and hardness affected by microstructure. In this study, SP-Creep ruptured test for newly developed 9Cr steel being used as boiler valve material was performed, and creep properties of the material were evaluated. Also, hardness test were performed and hardness results were related to the creep properties such as LMP and creep strength to verify the availability of SP-Creep test as creep test method.