• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.250-255
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• 2011

In this study, by using the polymeric membrane separation process, the $CO_{2}/CH_{4}$ separation and $H_{2}S$ removal from biogas were performed in order to $CH_{4}$ purification and enrichment for the fuel cell energy source application. Fibers were spun by dry/wet phase inversion method. The module was manufactured by fabricating fibers after surface coating with silicone elastomer. The scanning electron microscopy(SEM) studies showed that the produced fibers typically had an asymmetric structure; a dense top layer supported by a porous, sponge substructure. The permeance of $CO_{2}$ and $CO_{2}/CH_{4}$ selectivity increased with pressure and temperature. Mixture gas with increasing pressure and temperature, removal efficiency of the $CO_{2}$ and $H_{2}S$ were decreased while concentration of $CH_{4}$ was increased up to 100%. When retentate flow rate was increased with the decreasing of pressure and temperature the $CH_{4}$ recovery ratio in retentate side was increased while the $CH_{4}$ purity in retentate side was decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.363-363
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• 2008

The development of dry etching process for sapphire wafer with plasma has been key issues for the opto-electric devices. The challenges are increasing control and obtaining low plasma induced-damage because an unwanted scattering of radiation is caused by the spatial disorder of pattern and variation of surface roughness. The plasma-induced damages during plasma etching process can be classified as impurity contamination of residual etch products or bonding disruption in lattice due to charged particle bombardment. Therefor, fine pattern technology with low damaged etching process and high etch rate are urgently needed. Until now, there are a lot of reports on the etching of sapphire wafer with using $Cl_2$/Ar, $BCl_3$/Ar, HBr/Ar and so on [1]. However, the etch behavior of sapphire wafer have investigated with variation of only one parameter while other parameters are fixed. In this study, we investigated the effect of pressure and other parameters on the etch rate and the selectivity. We selected $BCl_3$ as an etch ant because $BCl_3$ plasmas are widely used in etching process of oxide materials. In plasma, the $BCl_3$ molecule can be dissociated into B radical, $B^+$ ion, Cl radical and $Cl^+$ ion. However, the $BCl_3$ molecule can be dissociated into B radical or $B^+$ ion easier than Cl radical or $Cl^+$ ion. First, we evaluated the etch behaviors of sapphire wafer in $BCl_3$/additive gases (Ar, $N_2,Cl_2$) gases. The behavior of etch rate of sapphire substrate was monitored as a function of additive gas ratio to $BCl_3$ based plasma, total flow rate, r.f. power, d.c. bias under different pressures of 5 mTorr, 10 mTorr, 20 mTorr and 30 mTorr. The etch rates of sapphire wafer, $SiO_2$ and PR were measured with using alpha step surface profiler. In order to understand the changes of radicals, volume density of Cl, B radical and BCl molecule were investigated with optical emission spectroscopy (OES). The chemical states of $Al_2O_3$ thin films were studied with energy dispersive X-ray (EDX) and depth profile anlysis of auger electron spectroscopy (AES). The enhancement of sapphire substrate can be explained by the reactive ion etching mechanism with the competition of the formation of volatile $AlCl_3$, $Al_2Cl_6$ or $BOCl_3$ and the sputter effect by energetic ions.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6191-6196
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• 2012

Aims and Background: Traditional chemotherapy strategies for human leukemia commonly use drugs based on cytotoxicity to eradicate cancer cells. One predicament is that substantial damage to normal tissues is likely to occur in the course of standard treatments. Obviously, it is urgent to explore therapies that can effectively eliminate malignant cells without affecting normal cells. Our previous studies indicated that ginsenoside $Rg_1$ ($Rg_1$), a major active pharmacological ingredient of ginseng, could delay normal hematopoietic stem cell senescence. However, whether $Rg_1$ can induce cancer cell senescence is still unclear. Methods: In the current study, human leukemia K562 cells were subjected to $Rg_1$ exposure. The optimal drug concentration and duration with K562 cells was obtained by MTT colorimetric test. Effects of $Rg_1$ on cell cycle were analyzed using flow cytometry and by SA-${\beta}$-Gal staining. Colony-forming ability was measured by colony-assay. Telomere lengths were assessed by Southern blotting and expression of senescence-associated proteins P21, P16 and RB by Western blotting. Ultrastructural morphology changes were observed by transmission electron microscopy. Results: K562 cells demonstrated a maximum proliferation inhibition rate with an $Rg_1$ concentration of $20{\mu}\;mol{\cdot}L^{-1}$ for 48h, the cells exhibiting dramatic morphological alterations including an enlarged and flat cellular morphology, larger mitochondria and increased number of lysosomes. Senescence associated-${\beta}$-galactosidase (SA-${\beta}$-Gal) activity was increased. K562 cells also had decreased ability for colony formation, and shortened telomere length as well as reduction of proliferating potential and arrestin $G_2$/M phase after $Rg_1$ interaction. The senescence associated proteins P21, P16 and RB were significantly up-regulated. Conclusion: Ginsenoside $Rg_1$ can induce a state of senescence in human leukemia K562 cells, which is associated with p21-Rb and p16-Rb pathways.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.61-66
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• 2018

This research scrutinizes the self-annealing characteristics of copper used to metal interconnection for application of DRAM fabrication process. As the time goes after the copper deposited, the grain of copper is growing. It is called self-annealing. We use the electroplating method for copper deposition and estimate two kinds of electroplating chemicals having different organic additives. As the time of self-annealing is elapsed, sheet resistance decreases with logarithmic dependence of time and is finally saturated. The improvement of sheet resistance is approximately 20%. The saturation time of experimental sample is shorter than that of reference sample. We can find that self-annealing is highly efficient in grain growth of copper through the measurement of TEM analysis. The structure of copper grain is similar to the bamboo type useful for current flow. The results of thermal excursion characteristics show that the reliability of self-annealed sample is better than that of sample annealed at higher temperature. The self-annealed sample is not contained in hillock. The self-annealed samples grow until $2{\mu}m$ and develop in [100] direction more favorable for reliability.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.37-42
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• 1999

In this paper, some of main processes for the next generation integrated circuits, such as Cu damascene process using CMP, electron beam lithography, $SiO_2$ CVD and RIE, Ti/Cu-CVD were carried cut and then, two level Cu interconnects were accomplished. In the results of CMP unit processes, a 4,635 ${\AA}$/min of removal rate, a selectivity of Cu : $SiO_2$ of 150:1, a uniformity of 4.0% are obtained under process conditions of a head pressure of 4 PSI, table and head speed of 25rpm, a oscillation distance of 40 mm, and a slurry flow rate of 40 ml/min. Also 0.18 ${\mu}m\;SiO_2$ via-line patterns are fabricated using 1000 ${\mu}C/cm^2$ dose, 6 minute and 30 second development time and 1 minute and 30 second etching time. And finally sub-0.2 ${\mu}$ twolevel metal interconnects using the developed processes were fabricated and the problems of multilevel interconnects are discussed.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.6039-6046
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• 2015

Aims: To investigate effect of metallic nanoparticles, silver (AgNPs) and gold nanoparticles (AuNPs) as antitumor treatment in vitro against human breast cancer cells (MCF-7) and their associated mechanisms. This could provide new class of engineered nanoparticles with desired physicochemical properties and may present newer approaches for therapeutic modalities to breast cancer in women. Materials and Methods: A human breast cancer cell line (MCF-7) was used as a model of cells. Metallic nanoparticles were characterized using UV-visible spectra and transmission electron microscopy (TEM). Cytotoxic effects of metallic nanoparticles on MCF-7 cells were followed by colorimetric SRB cell viability assays, microscopy, and cellular uptake. Nature of cell death was further investigated by DNA analysis and flow cytometry. Results: Treatment of MCF-7 with different concentrations of 5-10nm diameter of AgNPs inhibited cell viability in a dose-dependent manner, with IC50 value of $6.28{\mu}M$, whereas treatment of MCF-7 with different concentrations of 13-15nm diameter of AuNPs inhibited cell viability in a dose-dependent manner, with IC50 value of $14.48{\mu}M$. Treatment of cells with a IC50 concentration of AgNPs generated progressive accumulation of cells in the S phase of the cell cycle and prevented entry into the M phase. The treatment of cells with IC50 concentrations of AuNPs similarly generated progressive accumulation of cells in sub-G1 and S phase, and inhibited the entrance of cells into the M phase of the cell cycle. DNA fragmentation, as demonstrated by electrophoresis, indicated induction of apoptosis. Conclusions: Our engineered silver nanoparticles effectively inhibit the proliferation of human breast carcinoma cell line MCF-7 in vitro at high concentration ($1000{\mu}M$) through apoptotic mechanisms, and may be a beneficial agent against human carcinoma but further detailed study is still needed.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.6135-6140
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• 2013

Background: Breast cancer is a common malignant tumor which affects health of women and multidrug resistance (MDR) is one of the main factors leading to failure of chemotherapy. This study was conducted to establish paclitaxel-resistant breast cancer cell line and nude mice models to explore underlying mechanisms of MDR. Methods: The breast cancer drug-sensitive cell line MCF-7 (MCF-7/S) was exposed in stepwise escalating paclitaxel (TAX) to induce a resistant cell line MCF-7/TAX. Cell sensitivity to drugs and growth curves were measured by MTT assay. Changes of cell morphology and ultrastructure were examined by optical and electron microscopy. The cell cycle distribution was determined by flow cytometry. Furthermore, expression of proteins related to breast cancer occurrence and MDR was tested by immunocytochemistry. In Vivo, nude mice were injected with MCF-7/S and MCF-7/TAX cells and weights and tumor sizes were observed after paclitaxel treatment. In addition, proteins involved breast cancer and MDR were detected by immunohistochemistry. Results: Compared to MCF-7/S, MCF-7/TAX cells had a higher resistance to paclitaxel, cross-resistance and prolonged doubling time. Moreover, MCF-7/TAX showed obvious alterations of ultrastructure. Estrogen receptor (ER) expression was low in drug resistant cells and tumors while expression of human epidermal growth factor receptor 2 (HER2) and Ki-67 was up-regulated. P-glycoprotein (P-gp), lung resistance-related protein (LRP) and glutathione-S-transferase-${\pi}$ (GST-${\pi}$) involved in the MDR phenotype of resistant cells and tumors were all overexpressed. Conclusion: The underlying MDR mechanism of breast cancer may involve increased expression of P-gp, LRP and GST-${\pi}$.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.6007-6012
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• 2013

ANXA2, a member of the annexin family, is overexpressed and plays important roles in tumor development. However, the significance of ANXA2 expression in gastric carcinoma has not been clarified.To elucidate its roles in growth of gastric cancer, ANXA2 expression in SGC-7901 cells was inhibited with a designated siRNA, then cell proliferation, cell cycling, apoptosis and motility were determined by MTT assay, flow cytometry, Hoechst 33342 staining and wound healing assay, respectively. To further assess the behavior of ANXA2 deleted SGC-7901 cells, changes of microstructures were observed under fluorescence microscopy, laser scanning confocal microscopy and electron microscopy. We found that inhibition of ANXA2 expression caused cell proliferation to decrease significantly with G1 arrest, motility to be reduced with changes in pseudopodia/filopodia structure and F-actin and ${\beta}$-tubulin expression, and apoptosis to be enhanced albeit without significance. At the same time, ANXA2 deletion resulted in fewer pseudopodia/filopodia, non-stained areas were increased, contact inhibition among cells reappeared, and expression of F-actin and ${\beta}$-tubulin was decreased, with induction of polymerized disassembled forms. Taken together, these data suggest that ANXA2 overexpression is important to maintain the malignancy of cancer cells, and this member of the annexin family has potential to be considered as a target for the gene therapy of gastric carcinoma.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.239-246
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• 2014

A study on the elution characteristics of biostimulating agents (sulfate and nitrate) from biostimulants which are used for in-situ bioremediation for the coastal sediment contaminated with organic matter was performed. The biostimulating agents were mixed with the coastal sediment, and then massed the mixture into ball. Two kinds of ball type biostimulant were prepared by coating the ball surface with two different polymers, cellulose acetate and polysulfone. A granular type biostimulant (GTB) was also prepared by impregnating a granular activated carbon in the biostimulating agent solution. The image of scanning electron microscopy for the biostimulant coated with cellulose acetate (CAB) showed that the inner side of the coating layer consisted of irregular and bigger size of pores, and the surface layer had tight structure like beehive. For the biostimulant coated with polyfulfone (PSB), the whole coating layer had a fine structure without pore. The elution rate of the biostimulating agents for the CAB was higher than that for the PSB, and the elution rate for the GTB was considerably higher than that for the PSB in distilled water as well as in sea water. The elution rate of the biostimulating agents in turbulent water flow was about 3 times higher than that in standing water, and the elution rate of nitrate was higher than that of sulfate from the stimulating agents.

• Journal of the Mineralogical Society of Korea
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• v.29 no.3
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• pp.131-139
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• 2016

Detailed knowledge on maskelynite, a glassy phase of plagioclase found in shocked meteorites and impact craters, is essential to understand a shock metamorphism. Here, we explore an inhomogeneous shock metamorphism in the lunar meteorite Mount DeWitt (DEW) 12007 with an aim to understand the formation mechanism of maskelynite. Most plagioclase grains in the DEW 12007 partially amorphized into maskelynite with a unidirectional orientation. Back-scattered electron (BSE) images of maskelynite show a remnant of planar deformation fracture possibly indicating that the maskelynite would be formed by solid-state transformation(i.e., diaplectic glass). Plagioclase with flow texture is also observed along the rim of maskelynite, which would be a result of recrystallization of melted plagioclase. Results of Raman experiments suggest that shock pressure for plagioclase and maskelynite in the DEW 12007 is approximately 5-32 GPa and 26-45 GPa, respectively. The difference in shock pressures between plagioclase and maskelynite can be originated from 1) external factors such as inhomogeneous shock pressure and/or 2) internal factors such as chemical composition and porosity of rock. Unfortunately, Raman spectroscopy has a limitation in revealing the detailed atomic structure of maskelynite such as development of six- or five-coordinated aluminum atom upon various shock pressure. Further studies using nuclear magnetic resonance spectroscopy are necessary to understand the formation mechanism of maskelynite under high pressure.