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급냉 응고된 Al합금의 열처리에 따른 미세구조 및 기계적성질에 관한 연구
서동수,조성석,신용덕,김혜성,임승무 忠南大學校 産業技術硏究所 1988 산업기술연구논문집 Vol.3 No.2
Rapidly solidified A2024 alumium alloy plate and powder produced by the twin-roll method and the centrifugal atomization method, respectively. The microstructure and shape of the specimen were closely related to the process parameters. The process parameters of the twin-roll method must be properly combined in order to manufacture defect-free plate. Four kinds of powder shape were produced by the centrifugal atomization process, e.g. spherical, tear drop, ligamental and flake. The age hardening behavior of the rapidly solidified A2024 alloy was somewhat different from the conventional slowly solidified one.
Seong, Hye Rim,Wang, Cuicui,Irfan, Muhammad,Kim, Young Eun,Jung, Gooyoung,Park, Sung Kyeong,Kim, Tae Myoung,Choi, Ehn-Kyoung,Rhee, Man Hee,Kim, Yun-Bae The Korean Society of Ginseng 2022 Journal of Ginseng Research Vol.46 No.5
Background: Since ginsenosides exert an anti-thrombotic activity, blood flow-improving effects of DK-MGAR101, an extract of mountain ginseng adventitious roots (MGAR) containing various ginsenosides, were investigated in comparison with an extract of Korean Red Ginseng (ERG). Methods: In Sprague-Dawley rats orally administered with DK-MGAR101 or ERG, oxidative carotid arterial thrombosis was induced with FeCl<sub>3</sub> (35%), and their blood flow and occlusion time were measured. To elucidate underlying mechanisms, the cytoprotective activities on rat aortic endothelial cells (RAOECs) exposed to hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) were confirmed. In addition, the inhibitory activities of DK-MGAR101 and ERG on agonist-induced platelet aggregation, thromboxane B<sub>2</sub> production, and ATP granule release from stimulated platelets as well as blood coagulation were analyzed. Results: DK-MGAR101 containing high concentrations of Rb1, Rg1, Rg3, Rg5, and Rk1 ginsenosides (55.07 mg/g) was more effective than ERG (ginsenosides 8.45 mg/g) in protecting RAOECs against H<sub>2</sub>O<sub>2</sub> cytotoxicity. DK-MGAR101 was superior to ERG not only in suppressing platelet aggregation, thromboxane B<sub>2</sub> production, and granule release, but also in delaying blood coagulation, FeCl<sub>3</sub>-induced arterial occlusion, and thrombus formation. Conclusions: The results indicate that DK-MGAR101 prevents blood vessel occlusion by suppressing platelet aggregation, thrombosis, and blood coagulation, in addition to endothelial cell injury.
Hye-Rim Kim,Soo-Jeong Kwon,Swapan Kumar Roy,Seong-Woo Cho,Hag-Hyun Kim,Kab-Yeon Cho,Hee-Ock Boo,Sun-Hee Woo 한국작물학회 2015 Korean journal of crop science Vol.60 No.1
Platycodon grandiflorum, commonly known as Doraji in Korea, has a wide range of pharmacologic properties, such as reducing adiposity and hyperlipidemia, and antiatherosclerotic effects. However, the mechanisms underlying these effects remain unclear. In order to profile proteins from the nodal segment, callus, root and shoot, high throughput proteome approach was executed in the present study. Two dimensional gels stained with CBB, a total of 84 differential expressed proteins were confirmed out of 839 protein spots using image analysis by Progenesis SameSpot software. Out of total differential expressed spots, 58 differential expressed protein spots (≥ 2-fold) were analyzed using MASCOT search engine according to the similarity of sequences with previously characterized proteins along with the UniProt database. Out of 58 differential expressed protein, 32 protein spots were up-regulated such as ribulose- 1,5-bisphosphate carboxylase, endoplasmic oxidoreductin-1, heat stress transcription factor A3, RNA pseudourine synthase 4, cysteine proteinase, GntR family transcriptional regulator, E3 xyloglucan 6-xylosyltransferase, while 26 differential protein spots were down-regulated such as L-ascorbate oxidase precursor, late embryogenesis abundant protein D-34, putative SCO1 protein, oxygen-evolving enhancer protein 3. However, frequency distribution of identified proteins using iProClass databases, and assignment by function based on gene ontology revealed that the identified proteins from the explants were mainly associated with the nucleic acid binding (17%), transferase activity (14%) and ion binding (12%). In that way, the exclusive protein profile may provide insight clues for better understanding the characteristics of proteins and metabolic activity in various explants of the economically important medicinal plant Platycodon grandiflorum.
Quench Development in Superconducting Fault Current Limiters Based on YBCO Films
Hye-Rim Kim,Seong-Woo Yim,Sung-Yong Oh,Seung-Deok Yoo,Ok-Bae Hyun IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>We measured and analyzed quench development in superconducting fault current limiters (SFCLs) based on Au/YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> thin films, taking temperature dependence of thermal parameters into consideration. The SFCLs were fabricated by patterning Au/YBCO films grown on 100 mm-diameter sapphire substrates. They were subjected to simulated AC fault currents for quench development measurement. The samples were immersed in liquid nitrogen during the experiment. The quench resistance increased rapidly first and then moderately fast. The increase slowed down afterwards. Data were analyzed quantitatively with the concept of heat transfer within the SFCLs. A heat balance equation was derived and solved, taking into consideration temperature dependence of thermal parameters of sapphire substrates. The solutions agreed with data well. They explained the quench behavior both prior to and after completion of quench propagation. Dependence of quench development on applied voltages could be also understood quantitatively.</P>
Recovery Characteristics of Coated Conductors
Hye-Rim Kim,Chung Ryul Park,Seong-Woo Yim,Seung-Duck Yu,Ok-Bae Hyun IEEE 2010 IEEE transactions on applied superconductivity Vol.20 No.3
<P>We investigated recovery characteristics of commercially-available coated conductors (CCs) after quenches. The CC had a hastelloy substrate and an Ag protection layer without stabilizer. The CC samples were subjected to simulated AC over-current to induce quenches. Both resistance measurement and bubble imaging were taken during the recovery. The samples were immersed in liquid nitrogen during the experiment. During the recovery, resistance of CC samples decreased monotonously to zero in some cases. In other cases, it decreased in two steps, first slowly and then faster. Resistance behavior depended on voltages applied during over-current period as well as sample dimension. It was related to cooling by liquid nitrogen and recovery propagation behavior, which could be observed directly by bubble imaging. The bubble imaging and the resistance measurement results matched with each other. The recovery generally propagated faster in thinner and wider samples as well as when higher voltages were applied during the over-current period. This recovery behavior was understood quantitatively with the concept of heat transfer to the surrounding liquid nitrogen. Heat balance equation was solved, and the calculated data were compared with experimental results.</P>
Installation and Testing of SFCLs
Hye-Rim Kim,Seong-Eun Yang,Seung-Duck Yu,Heesun Kim,Woo-Seok Kim,Kijun Park,Ok-Bae Hyun,Byeong-Mo Yang,Jungwook Sim,Young-Geun Kim IEEE 2012 IEEE transactions on applied superconductivity Vol.22 No.3
<P>A 22.9 kV/630 A-class superconducting fault current limiter (SFCL) was installed on a distribution line in Icheon Substation for real-grid operation. The substation is located in a semi-urban area with moderate loads. The SFCL is of hybrid type. After installation it was subjected to a series of on-site tests. Test procedures were determined by following convention in testing both superconductivity-related and not-related specifications of the SFCL. Tests performed were minimum limiting current test, temperature test, dielectric test, and impedance measurement. After successfully passing the tests, the cooling system of the SFCL was operated for more than 5 months under various load conditions to optimize the operation condition. During that period, temperatures, liquid nitrogen level, and internal pressure remained within ±0.1 K, ±0.5 cm, and ±0.5 bar range, proving stability in cooling superconducting elements. The SFCL was then energized and went into real-load operation successfully.</P>