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Sung Ku Kwon,김병환,박종문,김보우,Seong Wook Yoo,Kun Sik Park,Yoon Kyu Bae,Kwang Ho Kwon 한국전자통신연구원 2002 ETRI Journal Vol.24 No.3
This study characterizes an oxide etching process in a magnetically enhanced reactive ion etching (MERIE) reactor with a CHF3/CF4 gas chemistry. We use a statistical 24-1 experimental design plus one center point to characterize the relationships between the process factors and etch responses. The factors that we varied in the design include RF power, pressure, and gas composition, and the modeled etch responses were the etch rate, etch selectivity to TiN, and uniformity. The developed models produced 3D response plots. Etching of SiO2 mainly depends on F density and ion bombardment. SiO2 etch selectivity to TiN sensitively depends on the F density in the plasma and the effects of ion bombardment. The process conditions for a high etch selectivity are a 0.3 to 0.5 CF4 flow ratio and a –600 V to –650 V DC bias voltage according to the process pressure in our experiment. Etching uniformity was improved with an increas e in the CF4 flow ratio in the gas mixture, an increase in the source power, and a higher pressure. Our characterization of via etching in a CHF3/CF4 MERIE using neural networks was successful, economical, and effective. The results provide highly valuable information about etching mechanisms and optimum etching conditions.
Optimization of Barium Titanate Slip for Tape Casting Using Design of Experiments
Kwon, Sung-Wook,Darsono, Nono,Yoon, Dang-Hyok The Korean Ceramic Society 2006 한국세라믹학회지 Vol.43 No.9
A full-factorial design of experiments with three input factors and two levels for each factor including center points was utilized for the preparation and characterization of twelve types of $BaTiO_3$ slips for tape casting. Ceramic powders with different particle sizes, different milling methods such as high energy milling and conventional ball milling, and two types of dispersant with different polymeric species were chosen as input factors in order to investigate their effects on slip and on green tape properties. Tape casting, a small rectangular-shaped K-square preparation, characterization and quantitative data analysis using statistical software were followed. Ceramic powder was the most significant among three input factors for the output responses of slip viscosity and green tape density, showing more favorable results with large particles than with very fine ones. In addition, high energy milling for only 30 min was more efficient than 24h of conventional ball milling in terms of powder dispersion and milling. The optimum condition based on the experimental results was a slip exposed to high energy milling with large ceramic particles along with a methylethyl acetate dispersant.
Kwon, Ji Hye,Park, Hee-Jin,Chitrapriya, Nataraj,Han, Sung Wook,Lee, Gil Jun,Lee, Dong Jin,Cho, Tae-Sub Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
The thermodynamic parameters for the intercalative interaction of structurally related well known intercalators, 9-aminoacridine (9AA) and proflavine (PF) were determined by means of fluorescence quenching study. The fluorescence intensity of 9AA decreased upon intercalation to DNA, poly[$d(A-T)_2$] and poly[$d(G-C)_2$]. A van't Hoff plot was constructed from the temperature-dependence of slope of the ratio of the fluorophore in the absence and presence of a quencher molecule with respect to the quencher concentration, which is known as a Stern-Volmer plot. Consequently, the thermodynamic parameters, enthalpy and entropy change, for complex formation was calculated from the slope and y-intercept of the van't Hoff plot. The detailed thermodynamic profile has been elucidated the exothermic nature of complex formation. The complex formation of 9AA with DNA, poly[$d(A-T)_2$] and poly[$d(G-C)_2$] was energetically favorable with a similar negative Gibb's free energy. On the other hand, the entropy change appeared to be unfavorable for 9AA-poly[$d(G-C)_2$] complex formation, which was in contrast to that observed with native DNA and poly[$d(A-T)_2$] cases. The equilibrium constant for the intercalation of PF to poly[$d(G-C)_2$] was larger than that to DNA, and was the largest among sets tested despite the most unfavorable entropy change, which was compensated for by the largest favorable enthalpy. The favorable hydrogen bond contribution to the formation of the complexes was revealed from the analyzed thermodynamic data.
Kwon, Seulgi,An, Sang Mi,Yu, Go Eun,Hwang, Jung Hye,Park, Da Hye,Kang, Deok Gyeong,Kim, Tae Wan,Park, Hwa Chun,Ha, Jeongim,Kim, Chul Wook,Plaizier, J. Canadian Science Publishing 2018 Canadian journal of animal science Vol.98 No.4
<P> Litter size is an important trait in the pig industry. Therefore, a lot of effort has been put into improving this trait. DNA methylation is an essential epigenetic modification present in unique DNA sequences. Alterations in methylation can affect transcription and phenotypic variation. The purpose of this study was to investigate the effect of DNA methylation on litter size. Methylation-specific restriction enzymes are simple and useful tools for detecting DNA methylation status. We used a pair of methylation-sensitive isoschizomers, which have the same recognition site, HpaII and MspI. Insulin-like growth factor binding protein 4 (IGFBP4) is a key regulator of ovarian follicular development and fetal growth in eutherian mammals. In this study, we discovered that IGFBP4 was hyper-methylated in the uterus tissue of a larger litter size group using bisulfite sequencing, and validated the positive relationship between the methylation status of IGFBP4 and the total number born of pigs using the porcine methylation-specific restriction enzyme polymerase chain reaction (PMP) assay. We suggest that the IGFPB4 gene can be used as a prognostic biomarker for hyperprolific sows and that the PMP assay is a useful tool for methylation status screening. </P>