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알루미늄 PEO 코팅의 결정상에 미치는 공정 조건에 대한 연구 I. Unipolar 펄스와 코팅시간
김배연,함재호,이득용,김용남,전민석,김기윤,최지원,김성엽,김광엽,Kim, Bae-Yeon,Ham, Jae-Ho,Lee, Deuk Yong,Kim, Yong-Nam,Jeon, Min-Seok,Kim, Kiyoon,Choi, Ji-Won,Kim, Sung Youp,Kim, Kwang Youp 한국결정성장학회 2014 韓國結晶成長學會誌 Vol.24 No.2
전해질로 $Na_2SiO_3$을 사용하여 A1050 알루미늄 판재를 pulse 폭 $ 2000{\mu}sec$, impulse 420 V, 400 ${\mu}$sec의 unipolar pulse로 플라즈마 전해 산화 코팅(plasma electrolytic oxidation coating)을 하여 산화 피막을 2, 5, 15, 30분에 따라 형성시킨 다음 산화피막을 분석하였다. 표면에 형성된 산화물의 결정상은 ${\alpha}-alumina$와 ${\gamma}-Alumina$로서 시간에 따른 변화는 없었다. 반응 초반에는 ${\gamma}-Alumina$가 많이 생성되었지만 시간이 갈수록 ${\gamma}-Alumina$의 양에는 변화 없이 ${\alpha}-alumina$가 많이 생겨남을 알 수 있었다. 이런 결과는 micro plasma에 의해서 ${\gamma}-Alumina$가 우선 생성되고, 이후 계속되는 micro plasma의 열에 의해서 ${\alpha}-alumina$로의 전이가 일어나기 때문으로 판단된다. Crystallographic phases of Plasma electrolytic oxidized Al alloy, A1050, were investigated. The electrolyte of PEO was $Na_2Si_2O_3$ and KOH. Unipolar pulse, $ 2000{\mu}sec$ with $400{\mu}sec+420V$ impulse, were applied for 2 min, 5 min, 15 min, and 30 min. ${\gamma}-Alumina$, as well as ${\alpha}-alumina$, was main crystal phase. ${\gamma}-Alumina$ was appeared in the beginning, then the amount of ${\alpha}-alumina$ was increased with time, but the amount of ${\gamma}-Alumina$ remained constant without any increasing. So, it is concluded that plasma gas produce ${\gamma}-Alumina$ at the first, and then ${\gamma}-Alumina$ transform ${\alpha}-alumina$ finally. During the transformation, high temperature of micro plasma gives transformation energy.
알루미늄 PEO 코팅의 결정상에 미치는 공정 조건에 대한 연구 II. Bipolar 펄스와 전해액
김배연,함재호,이득용,김용남,전민석,김기윤,최지원,김성엽,김광엽,Kim, Bae-Yeon,Ham, Jae-Ho,Lee, Deuk Yong,Kim, Yong-Nam,Jeon, Min-Seok,Kim, Kiyoon,Choi, Ji-Won,Kim, Sung Youp,Kim, Kwang Youp 한국결정성장학회 2014 한국결정성장학회지 Vol.24 No.2
A1100, A5052, A6061, A6063, A7075 규격의 시판 알루미늄 합금 판재를 $Na_2SiO_3$와 $Na_2P_2O_7$ 전해질에서 pulse폭 $2000{\mu}sec$, + impulse 420 V, $400{\mu}sec$, -impulse $300{\mu}sec$의 bipolar pulse로 플라즈마 전해 산화 코팅(plasma electrolytic oxidation coating)한 산화피막의 결정상을 분석하였다. 표면에 형성된 산화물의 결정상은 ${\alpha}-alumina$, ${\gamma}-alumina$, ${\eta}-alumina$, $Al_{4.95}Si_{1.05}O_{9.52}$, 그리고 $(Al_{0.9}Cr_{0.1})_2O_3$가 관찰되었다. Bipolar pulse에 의해서 전해액의 성분인 Si가 산화피막에 포함되며, 포함된 Si는 결정상을 형성하기도 하지만 유리상을 형성시킨다. 이때 합금의 Mg 성분은 유리상의 양을 증가시킨다. Micro plasma에 의해서 용융된 표면은 유리상이 먼저 형성되고 이후 계속된 micro plasma의 열에 의하여 새로운 결정상으로 전이가 일어나는 과정을 거치며, 이에 따라 기존에 보고된 결정상이외에도 다양한 결정상이 형성될 수 있음을 추측할 수 있다. Crystallographic phases of Plasma electrolytic oxidized Al alloy, A1100, A5052, A6061, A6063, A7075, were investigated. Two types of electrolyte $Na_2Si_2O_3$ and Na2P2O7 were also compared. Bipolar pulse, $2000{\mu}sec$ with $400{\mu}sec+420V$ impulse and $300{\mu}sec$ - impulse were applied for 20 min. ${\alpha}-alumina$, ${\gamma}-alumina$, ${\eta}-alumina$, $Al_{4.95}Si_{1.05}O_{9.52}$, and $(Al_{0.9}Cr_{0.1})_2O_3$ were mainly observed. Si, component of electrolyte, were moved into the PEO layer by bipolar pulse. Glassy phase was also observed at the surface of $Na_2Si_2O_3$ electrolyte treated PEO layer, and increased with the Mg content of Al alloy. It is concluded that at first glassy phase was formed by the micro plasma, and the high temperature of plasma turns glassy phase to several crystalline phases. And we could expect that many other crystalline phase could be formed by PEO process.
Kiyoon Kim,Rashedul Islam,Abitha Benson,Manoharan Melvin Joe,Walitang Denver,Mak Chanratan,Poulami Chatterjee,Yeongyeong Kang,Tongmin Sa 한국토양비료학회 2016 한국토양비료학회지 Vol.49 No.2
Soil is a dynamic biological system, in which it is difficult to determine the composition of microbial communities. Knowledge of microbial diversity and function in soils are limited because of the taxonomic and methodological limitations associated with studying the organisms. In this review, approaches to measure microbial diversity in soil were discussed. Research on soil microbes can be categorized as structural diversity, functional diversity and genetic diversity studies, and these include cultivation based and cultivation independent methods. Cultivation independent technique to evaluate soil structural diversity include different techniques such as Phospholipid Fatty Acids (PLFA) and Fatty Acid Methyl Ester (FAME) analysis. Carbon source utilization pattern of soil microorganisms by Community Level Physiological Profiling (CLPP), catabolic responses by Substrate Induced Respiration technique (SIR) and soil microbial enzyme activities are discussed. Genetic diversity of soil microorganisms using molecular techniques such as 16S rDNA analysis Denaturing Gradient Gel Electrophoresis (DGGE) / Temperature Gradient Gel Electrophoresis (TGGE), Terminal Restriction Fragment Length Polymorphism (T-RFLP), Single Strand Conformation Polymorphism (SSCP), Restriction Fragment Length Polymorphism (RFLP) / Amplified Ribosomal DNA Restriction Analysis (ARDRA) and Ribosomal Intergenic Spacer Analysis (RISA) are also discussed. The chapter ends with a final conclusion on the advantages and disadvantages of different techniques and advances in molecular techniques to study the soil microbial diversity.
Kiyoon Kim,Chaemin Kwak,Youngwook Lee,Tongmin Sa 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.1
The objective of this study was to determine the effect of single and co-inoculation of plant growth promoting bacteria (PGPB) on early plant growth in Saemangeum reclaimed soil. Plant growth promoting Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 were inoculated on maize (Zea mays L.) and sorghum-sudangrass hybrid (Sorghum bicolor L.) grown in Saemangeum reclaimed soil. Single and co-inoculation of B. iodinum RS16 and M. oryzae CBMB20 increased plant height, dry biomass accumulation and macro-nutrient accumulation of maize and sorghum-sudangrass hybrid. M. oryzae CBMB20 treatment increased plant height in maize by 41.2% at 30 days after sowing (DAS), shoot dry weight and total dry weight compared to non-inoculated treatment. Macro-nutrient accumulation (N and P) in maize roots was significantly increased with co-inoculation treatment, K and Ca content was significantly increased at B. iodinum RS16 treatment compared to non-inoculated treatment. Macro-nutrient accumulation (P, K, Ca and Mg) in shoot was higher with M. oryzae CBMB20 treatment compared to non-inoculated treatment. In case of sorghum-sudangrass hybrid, co-inoculation treatment showed 33.7% increase in plant height compared to non-inoculated treatment at 30 DAS. M. oryzae CBMB20 treatment increased root dry weight and total dry weight, macro-nutrient accumulation in roots and N, Ca and Mg accumulation in shoot compared to non-inoculated treatment. P and K accumulation in shoot was significantly increased at co-inoculation treatment compared to non-inoculated treatment. This pot culture experiment demonstrated that single and co-inoculation of B. iodinum RS16 and M. oryzae CBMB20 increased the early growth and nutrient accumulation of maize and sorghum-sudangrass hybrid.
Kiyoon Kim,Seongwoong Hwang,Venkatakrishnan Sivaraj Sarava,Tongmin Sa 한국토양비료학회 2012 한국토양비료학회지 Vol.45 No.1
Salinity is one of the most relevant abiotic factor limiting crop yield and its net primary productivity. In addition, salinity induces an increased stress ethylene synthesis in plants which, in turn, exacerbate the responses to the stressor. Bacterial single or co-inoculation effect was tested using previously characterized plant growth promoting (PGP) bacteria Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 on maize and sorghum-sudan grass hybrid under different concentrations of NaCl. Non-inoculated maize and sorghum-sudangrass hybrid showed 33.4% and 20.0% reduction in seed germination under highest NaCl (150 mM) level tested. However, under the same NaCl concentration, co-inoculation with B. iodinum RS16 and M. oryzae CBMB20 PGP strains increased the seed germination in maize (16.7%) and sorghumsudangrass hybrid (4.4%). In Gnotobiotic growth pouch experiments conducted for maize and sorghumsudangrass hybrid, co-inoculation of PGP B. iodinum RS16 and M. oryzae CBMB20 mitigated the salinity stress and promoted root length by 22.9% and 29.7%, respectively. Thus the results of this study could help in development of potential bioinoculants that may be suitable for crop production under saline conditions.
Kim, Kiyoon,Kim, Hunsung,Jeong, Kwon,Jung, Min Hyung,Hahn, Bum-Soo,Yoon, Kyung-Sik,Jin, Byung Kwan,Jahng, Geon-Ho,Kang, Insug,Ha, Joohun,Choe, Wonchae Rapid Science Publishers ; Kluwer Academic Publish 2012 Apoptosis Vol.17 No.8
<P>Cyclophilin, a cytosolic receptor for the immunosuppressive drug cyclosporin A, plays a role in diverse pathophysiologies along with its receptor, CD147. Although the interaction between cyclophilin A and CD147 is well established in inflammatory disease, that of cyclophilin B (CypB) with CD147 has not been fully explored, especially in cancer cell biology, and the exact molecular mechanism underlying such an association is poorly understood. In this study, we first identified high expression levels of CypB in 54 % of hepatocellular carcinoma patient tissues but in only 12.5 % of normal liver tissues. Then, we demonstrated that CypB overexpression protects human hepatoma cells against oxidative stress through its binding to CD147; this protective effect depends on the peptidyl prolyl isomerase activity of CypB. siRNA-mediated knockdown of CypB expression rendered hepatoma cells more vulnerable to ROS-mediated apoptosis. Furthermore, we also determined that a direct interaction between secreted CypB and CD147 regulates the extracellular signal-regulated kinase intracellular signaling pathway and is indispensible for the protective functions of CypB. For the first time, we demonstrated that CypB has an essential function in protecting hepatoma cells against oxidative stress through binding to CD147 and regulating the ERK pathway.</P>