• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.

• Textile Coloration and Finishing
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• v.19 no.3
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• pp.26-36
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• 2007

This study was carried out to treat the aqueous solutions containing reactive dyes(RB19, RR120 and RY179) by the Ozone demand flask method and adsorption process using activated carbon fiber(ACF) which are one of the main pollutants in dye wastewater. Ozone oxidation of three kinds of the reactive dyes was examined to investigate the reactivity of dyes with ozone, competition reaction and ozone utilization on various conditions for single- and multi-solute dye solution. Concentration of dyes was decreased continuously with increasing ozone dosage in the single-solute dye solutions. Competition quotient values were calculated to investigate the preferential oxidation of individual dyes in multi-solute dye solutions. Competition quotients(CQi) and values of the overall utilization efficiency, ${\eta}O_3$, were increased at 40mg/l of ozone dosage in multi-solute dye solutions. ACF(A-15) has much larger specific surface area$(1,584m^2/g-ACF)$ in comparison with granular activated carbon adsorbent (F400, $1,125m^2/g-GAC$), which is commonly used, and most of pores were found to be micropores with pore radius of 2nm and below. It was found that RB19 was most easily adsorbed among the dyes in this study. In the case of PCP (p-chlorophenol) and sucrose, which are single component adsorbate, adsorption capacities of ACF(A-15) were in good agreement with the batch adsorption measurement, and saturation time predicted of ACF columns for these components was also well agreed with practically measured time. But in the case of reactive dyes, which have relatively high molecular weight and aggregated with multi-components, adsorption capacities or saturation time predicted were not agreed with practically measured values.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.232-238
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• 2019

Polyethylenimine-crosslinked chitin (PEI-chitin) was developed as a biosorbent to effectively remove dyestuffs from dye-containing wastewater. A representative reactive dye, Reactive Orange 16 (RO16) was used as a model dye. The effect of pH, isotherm, kinetic and desorption experiments were performed to evaluate the adsorption/desorption ability of PEI-chitin for RO16. As a result, the maximum adsorption capacity calculated by the Langmuir model was 266.3 mg/g at pH 2, and the time needed for adsorption equilibrium was evaluated to be about 20, 60, and 240 min for 50, 100, and 200 mg/L, respectively. The desorption experiments were carried out using various eluents such as ammonia/ethanol mixture, NaOH, $NaHCO_3$, and $Na_2CO_3$, and the highest desorption rate was 75.24% in the ammonia/ethanol mixture.

• Journal of Adhesion and Interface
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• v.4 no.2
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• pp.30-36
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.59-60
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• 1992

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.167-167
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• 1997

• Proceedings of the Korean Vacuum Society Conference
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• 1993.02a
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• pp.109-109
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• 1993

• Proceedings of the Korean Vacuum Society Conference
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• 2002.06a
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• pp.177-177
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• 2002

• Journal of Microbiology
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• v.45 no.6
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• pp.547-552
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• 2007

Previously, we generated monoclonal antibodies (MAbs) that bound to the surface of human embryonic stem cells (hESCs) in an attempt to discover new hESC-specific surface markers. In this study, MAb 47-235 (IgG1, ${\kappa}$) was selected for further characterization. The MAb bound to the surface of undifferentiated hESCs but did not bind to mouse ESCs or mouse embryonic fibroblast cells in flow cytometric analysis. The antibody immunoprecipitated a 47 kDa protein from the lysates of cell surface-biotinylated hESCs. Identification of the protein by quadrupole time of flight tandem mass spectrometry revealed that 47-235 binds to Ag 243-5 protein of Mycoplasma arginini. BM-Cyclin treatment of the hESCs that reacted with 47-235 resulted in loss of mycoplasma DNA and the reactivity to 47-235. Nevertheless, the hESCs that were reactive to 47-235 maintained self-renewal and pluripotency and thus could be differentiated into three embryonic germ layers.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.61-62
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• 2002

In order to clarify the contact mechanism between specimen surface and probe tip in the surface observation by the AFM (atomic force microscope) or the FFM (friction force microscope), several molecular dynamics simulations have been performed. In the simulation, a 3-dimensional simulation model is proposed where the specimen and the probe are assumed to consist of mono-crystal line copper and a carbon atom respectively and the effect of cantilever stiffness is also taken into considered. The surface observation process on a well-defined Cu{100} is simulated. The influences of cantilever stiffness on the reactive force images and the behavior of probe tip were evaluated. As a resuIt, several phenomena similar to those observed by the actual surface observation experiment, such as double-slip behavior and dispersion in the stick-slip wave period were observed.