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제주연안 갯녹음(백화) 지역의 해수에 분포하는 세균군의 분자생물학적 분석
강봉조,김미란,윤병준,이동헌,오덕철,강형일 濟州大學校 基礎科學硏究所 2002 基礎科學硏究 Vol.15 No.2
본 연구에서는 갯녹음(백화)현상이 세균생태계와 어떤 관련이 있는지에 대한 기초자료 및 정보를 얻기 위하여 갯녹음 현상이 일어난 제주도 성산과 강정지역 연안의 해수에 존재하는 세균군을 16S rRNA 증폭기법을 이용하여 조사하였다. 강정지역에서는 Alcanivorax, Paracoccus, Damselae, Pseudomonas, Rhodovulum, Silicibacter, Sulfitobacter, Roseobacter 등 다양한 종류의 세균이 분포되어 있었으며, Alcanivorax가 20%의 빈도로 가장 많이 나타났다. 반면, 성산 지역에서는 Pseudomonas속 균주가 우점종으로서 존재하였으며, Pseudomonas tolaasii(혹은 Pseudomonas corrugata)와 유연관계가 가까운 세균은 44%, Pseudomonas mandeli와 가까운 세균이 24%, Verrucomicrobiales와 가까운 세균은 4%, 기타 동정되지 않은 세균은 세 group으로 구분되었으며, 각각 8%, 8%, 12%를 차지하여, 두 곳에 분포되어 있는 세균군상이 상당한 차이점이 있음을 확인하였다. 갯녹음 지역인 강정과 성산 해수의 8월(표품 채집시기)의 수온은 27℃-27.5℃, 염분의 농도는 30.24-30.60%, pH는 8.23-8.36, 용존산소량(DO)은 각각 7.20-7.28로, 두 지역에서 매우 비슷한 것으로 조사된 바 있는데, 이는 수온이나 염분의 농도, 또는 pH보다는 다른 원인에 의하여 두 갯녹음 지역에 분포하는 세균군의 차이를 가져왔음을 제시해 주었다. In this study, the bacterial communities distributed in sea water of the whitening areas of Gangjeong and Seongsan, Jeju-do have been analyzed using the PCR amplification of 16S rRNA to obtain fundamental data and information on relationship of the whitening phenomenon and microbial ecosystem. In Gangjeong, diverse bacteria such as Alcanivorax, Paracoccus, Damselae, Pseudomonas, Rhodovulum, Silicibacier, Sulfitobacter, and Roseobacier have been found, and Alcanivorax was the most abundant clone. The most abundant clone from Seongsan was Pseudoinonas, of which Pseudomonastolaasii and Pseudonionas mandeli were most abundantly occurred in the frequency of approx 44% and 24%, respectively. Approx 4% of the bacterial clones closest to firruconiicrobiales and other unidentified clones were also found in Seongsan, suggesting there is a great discrepancy between bacterial communities from the whitening areas of Seongsan and Gangjeong. The mean tem- perature, chlorine concentration, pH, and dissolved oxygen (DO) of the sea water of Gangjeong and Seongsan in August of 2001 (sampling period) was 27℃-27.5℃, 30.24-30.60%, pH 8.23-8.36,7.20-7.28 ㎎/ℓ, suggesting other environmental factors except for the factors mentioned above might result in difference of bacterial communities distributed in both areas.
조철형,조성휴,조병욱,김정규,김숭평,권중근 조선대학교 생산기술연구소 1983 生産技術硏究 Vol.1983 No.-
Copolyesters containing oxybenzoate as a rigid rod molecule and methylene group and dimethyl tetramethyl disiloxane as flexible spacers were prepared by room temperature solution polymerization for the purpose of the developement of polymeric composite materials. The thermal properties and the characteristics of the polymers were investigated by DSC and a polarizing microscope. The polymers may be formed nematic liquid crystal phase, and the thermodynamic characteristics of their mesophase to isotropic phase transition could be explained on the basis of its structural features.
MoSi_2기 복합재료의 소결온도에 따른 미끄럼마모 특성
이광영,박원조,허선철,김형진,박성호 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-
Molybdenum disilicide(MoSi_2) is considered to be a promising high temperature material for turbojet anhypersonic engines in aerospace and various industrial applications, because of a high melting point(2030℃),adequate density(6.3g/cm^3) and an excellent oxidation resistance. Mosi2 powder was evaluated from the variation of fabricating such as preparation temperature 1250℃, 1350℃ and 1500℃ respectively. Abrasion tester used a pin-on-disk type and a Si3N4 ceramic ball which used as machine structural materials. The test condition apply to load of 8kgf at 7.5rpm for 6 hours and the effect of hardness is also discussed. As a result of the tests, the friction coefficient was decreased with sintered MoSi_2 of increasing temperature but the function coefficient did not vary much for all specimens at all temperatures.
Hyung-Chul Jo,Sung-Kwan Joo Institute of Electrical and Electronics Engineers 2017 IEEE transactions on applied superconductivity Vol.27 No.4
<P>In a medium-voltage power system, fault currents are subjected to uncertainties in lines and distributed generations. Uncertainties in fault currents in a power grid can introduce system protection problems. Superconducting cable with fault current limiting capability can be used as means to meet the increasing electricity demand while resolving the issues involving system protection. In order to integrate the fault current limiting superconducting cable into a power grid, its impedance selection under fault conditions needs to consider the impact of power system uncertainties on system protection. In this paper, an expected regret-based method is proposed for determining the impedance of the fault current limiting superconducting cable incorporating the uncertainties in fault currents. The results of numerical simulations are presented to show the effectiveness of the proposed expected regret-based impedance selection method.</P>
Hyung-Chul Jo,Sung-Kwan Joo,Kisung Lee IEEE 2013 IEEE transactions on applied superconductivity Vol.23 No.3
<P>Power flow patterns and fault current levels are influenced by the introduction of distributed generations (DGs) in an electric power system. In particular, the change in the fault current levels caused by DG installation may require a change in the coordination of relays to prevent their misoperation. When DGs are installed in an electric power system, superconducting fault current limiters (SFCLs) can be used to help reduce the fault currents within the breaking capacity of the protective devices. In this paper, multiple criteria such as the number of SFCLs, fault current reduction, and the total operating time of the relays are considered in order to determine the optimal placement of SFCLs for protection of an electric power system with DGs, and a scenario optimization based approach is used to solve the multi-criteria SFCL placement problem. Numerical simulations are also carried out to demonstrate the effectiveness of the proposed approach.</P>
Hyung-Chul Jo,Sung-Kwan Joo Institute of Electrical and Electronics Engineers 2015 IEEE transactions on applied superconductivity Vol.25 No.3
<P>In a power grid, the distributed generations (DGs) are not generally controlled by the system operator. Fault current levels in the power grid may change because of unpredictable changes in the status of noncontrollable DGs. These changes in the fault current can have an impact on the relay coordination. In this paper, the uncertainty associated with the connection status of DGs is reflected in the relay coordination. Superconducting fault current limiter (SFCL) placement can be effective for reducing the fault current while eliminating misoperation of the relays caused by DGs. However, an SFCL may also have a negative impact on the operation of the relays. An effective SFCL placement method is needed because of the high cost of the SFCL and the impact on the power system protection. In this paper, an SFCL placement method based on the minimax regret criterion is proposed for power system protection considering the uncertainty of the DGs.</P>