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정지원,김기영,하명구,신용국,이태호,이재동 한국생명과학회 1998 한국생명과학회 학술발표회 Vol.20 No.-
This study was carried out to identify the phylogenetic relationship among Phellinus species by comparing the DNA sequences of the 5.8S ribosomal DNA (rDNA) and the internal transcribed spacers (ITS), ITS 1 and ITS 2 region. Two primers from 3´end of 18S rDNA and 5´end of 28S rDNA sequences were chosen to amplify the specific ITS region of Phellinus spp. Phellinus strains used in the study were divided into four clusters by phylogenetic tree based on the ITS and 5.8S rDNA sequences. The first and second cluster consist of Phellinus linteus strains and KCTC 6230 Phellinus laeuigatus, respectively. KCTC 6229 Phellinus laeuigatus and KCTC 6226 Phellinus chrysoloma belong to the third cluster. Finally, KCTC 6228 Phellinus igniarius strain showed the similar sequences as KCTC 6225 Phellinus chrysoloma. These results revealed that the differentiation within Phellinus species by the comparison of ITS sequences might be misleading the classification. Therefore, both physiological and molecular biological methods as well as the sequences of type strains are necessary to classify the strain accuarely. Six representative species of the Phellinus linteus were easily differentiated with other species by the differences of the length in ITS 1 and ITS 2 regions. The comparison of the nucleotide sequences of four. Phellinus species indicated that the sequences of ITS 1 generally exhibited more divergent than that of the ITS 2. Although the interstrain ITS sequences are varied in some species, it is useful to identify the conserved regions in both ITSs to differentiate the species. The distinct ITS sequences of Phellinus linteus will be useful for the development of the genetic probe to identify the Phellinus linteus strains from other Phellinus spp.
Materials and nano‑structural processes for use in solid oxide fuel cells: a review
Seungyeon Jo,Bharat Sharma,Dae‑Hwan Park,Jea‑ha Myung 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.2
Solid oxide fuel cells (SOFCs) are considered to be the focus of investigation for energy systems owing to their efficiency in converting chemical energy into electrical energy, low carbon footprint, and fuel flexibility. Despite their high performance and durability, SOFCs suffer from critical problems such as carbon coking, agglomeration, and poor redox stability. This review presents research on the development of nanostructures for use in commercial SOFC systems and highlights various aspects of research and applications across the globe. The materials utilized for anodes, electrolytes, and cathodes are discussed and compared, detailing how their respective properties can attain high catalytic activity, conductivity, and stability at low temperatures with the aim of direct application using diverse fuels such as hydrogen, hydrocarbons, and carbon fuels. This review also discusses and compares the various processes used for the synthesis of the electrodes and electrolytes used in SOFCs, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), infiltration, and in situ exsolution, that have gained much attention with a view to increase the active areas, decrease the Ohmic resistance, and reduce the manufacturing price.
다구찌 실험계획법을 이용한 소구경화기 총열 내부용 Cr-Mo-V강의 질화공정 최적화
권혁린(Hyuk-Rin Kwon),김동은(Dong-Eun Kim),손형동(Hyung-Dong Son),신재원(Jea-Won Shin),박재하(Jae-Ha Park),강명창(Myung-Chang Kang) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.3
When shooting small arms, the inner surface temperature is heated up to about 700~1,000℃ by the friction of the bullet and the inner wall of the barrel and the combustion of propellant. High-temperature propellant gas and high-speed movement of the bullet cause corrosion of the inner wall, which is noticeable immediately in front of the chamber. In this study, the mechanical properties of Cr-Mo-V steel, which is the base material, were tested using Taguchi experimental design to find the best nitriding treatment conditions. For the nitriding process, the working time, salt bath temperature, and salt concentration were combined as three conditions and placed in the L9(3⁴), orthogonal array table. The thicknesses of the white layer and the nitrogen diffusion layer were measured after nitriding under each condition in a salt bath furnace. Durability was evaluated by measuring the degree of dispersion through actual shooting because it was difficult to evaluate the mechanical properties of the cylinder inner structure. As a result, it was confirmed that the durability was optimal at 565℃, 1 hour, 0.5%. These optimal conditions were selected by the statistical analysis of the Minitab program(ver.17).