• Korean Journal of Materials Research
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• v.12 no.4
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• pp.235-239
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• 2002

In this study mesh-type PECVD system was suggested to minimize the hydrogen concentration. The main structural difference between the triode system and a conventional system is that, a third electrode, a mesh, is inserted between the powered and the ground electrode. We investigated several conditions to compare with conventional PECVD. The main effect of mesh was to minimize the substrate damage by ion bombardment and to enhance the surface reaction to induce hydrogen desorption. It was also found that hydrogen concentration decreased but deposition rate increased as increasing applied bias. Applied DC-bia s enhanced sputtering process. Intense ion bombardment causes the weakly bonded hydrogen or hydrogen-containing species to leave the growing film and increased adatom mobility. Furthermore, addition of hydrogen gas enhance the surface diffusion of adatom.

• KSBB Journal
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• v.11 no.3
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• pp.276-287
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• 1996

Batch suspension cultures of hybridoma cell were performed with various initial glutamine concentrations to investigate the effects of glutamine on cell growth and death, monoclonal antibody production, glucose and glutamine consumption, and the production of lactate and ammonium ion. An mathematical kinetic model was formulated to describe the kinetics of cell growth, the consumption of nutrients (glucose and glutamine), and the production of monoclonal antibody and waste metabolites (lactate and ammonium ion) based on experimental data. An equation for the specific growth rate was developed such that superimposed Monod equation in glucose and glutamine, with non-competitive type inhibition relations in ammonium ion and lactate. The inhibition constant for lactate was inversely proportional to the lactate concentration. The specific death rate was considered to be a function of glucose, glutamine, ammonium ion and lactate concentration.

• KSBB Journal
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• v.10 no.3
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• pp.323-334
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• 1995

The effects of glucose on cell growth kinetics, monoclonal antibody productivity, and cell metabolism or hybridoma cells were investigated. The mouse-mouse hybridoma cell line VIII H-8 producing mouse IgG2a was used as a modal system. Glucose showed substrate inhibition type dependence on specific growth raie. The maximum cell density increased as initial glucose concentration increased up to 4 g/$\ell$. Glucose showed a strong influence on cell death kinetics, and an inverse relationship between specific death rate and glucose concentration was found. Cell viability and monoclonal antibody production increased as initial glucose concentration increased. The specific glucose consumption rate increased with glucose concentration, and cumulative specific lactate production rate increased with increasing initial glucose concentration. The overall kinetics of ammonium ion production was almost invariant with respect to initial glucose concentration, while the cumulative specific ammonium ion production rate was dependent on initial glucose concentration.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.48-56
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• 1999

In this paper, we have investigated experimentally the effects of initial oxygen concentration on oxygen pileup phenomenon and the diffusion of implanted impurities. 1.2 MeV $^{11}B^{+}$ and 2.2 MeV $^{31}P^{+}$ ions were implanted into p-type (100) Si wafers with a dose of 1${\times}10^{15}$ / $\textrm{cm}^2$. Secondary ion mass spectrometry(SIMS) measurements were carried out to obtain depth distribution profiles for implanted impurities and oxygen atoms after two-step annealing of $700^{\circ}C$(20 hours)+$1000^{\circ}C$(10 hours). Residual secondary defect distribution and annealing behabiour were also studied by cross-sectional transmission electron microscopy(TEM) observations. Oxygen pileup nearly $R_p$(projected range) were observed by SIMS measurements and considerable amount of residual secondary defect layer were observed by TEM observations. It can be seen that oxygen atoms are trapped at the secondary defects by the experimental results. Enhanced diffusions of boron and phosphorus to the bulk direction were observed with the increasing of initial oxygen concentration.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.535-541
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• 2017

On the basis of 200 ppm of Ag and 120 l/h of feed flow rate, we built a pilot plant of an ion exchange fiber system having an double tube type ion exchange chamber with strong base ion exchange fiber (FIVAN A-6) which was designed to replace fibers easily and to eliminate the need for a fixture. The following results were obtained for the double tube type of ion exchange fiber system with an ion exchange capacity of 4.6 meq/g for Ag. The adsorption process was operated in the range of 40~90 l/h after confirming the effect of the flow rate and, pH did not affect formation of complex ion of Ag in the range of pH 7~12. In the case of backwash process, the recovery rate of Ag was tested in the range of 60~120 l/h and comparative experiments were carried out using NaOH, $NH_4Cl$, and NaCl as the chemicals for backwash. Although the desorption time was shortened at higher concentration, the desorption efficiency per mol was lowered. Therefore, it was confirmed that the desorption time and the concentration should be well balanced to operate economically. The desorption pattern of the backwash process is slower than the adsorption process and takes a lot of time. The results showed that the Ag adsorption ratio was 99.5% or more and the Ag recovery ratio was 96% or more, and commercialization was possible.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.889-892
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• 2004

Acicular type aragonite precipitated calcium carbonate was synthesized by carbonation reaction of $Ca(OH)_2$ slurry and $CO_2$ gas. As increasing the initial concentration of $Mg^{2+}$ ion, calcite crystal phase substantially decreased while that of aragonite crystal phase increased. According to XRD and EDS analysis, it was found that the addition of $MgCl_2$ induced the $Mg^{2+}$ ion to substitute in $Ca^{2+}$ ion site of calcite lattice then the unstabled calcite structure be resolved, consequently the growth of calcite structure is interrupted while the growth of aragonite structure is expedited.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.726-730
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• 2019

The removal of calcium ions using zeolite to solve problems of the CaCO₃ manufacturing process using cement kiln dust was investigated. To do so, a modified zeolite was employed and experiments were conducted to select the optimal zeolite type considered the binding cation and structure, evaluate the removal performance of calcium ions, the influence of the type and concentration of the modifying solution, and the removal selectivity when K coexists. Among five zeolites, 13X zeolite was found to have the best calcium ion removal performance, and it was confirmed that the removal performance was enhanced when KCl was used as a modifying solution instead of NaCl. This study is expected to be the basis for the solution of carbonation process and high concentration of KCl recovery technology.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.696-700
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• 1999

A method has been developed for the determination of trace anion impurities in concentrated hydrogen peroxide. The method involves on-line decomposition of hydrogen peroxide, ion chromatographic separation and subsequent suppressed-type conductivity detection. H2O2 is decomposed in Pt-catalyst filled Gore-Tex membrane tubing and the resulting aqueous solution containing analytes is introduced to the injection valve of an ion chromatograph for periodic determinations. The oxygen gas evolving within the membrane tubing escapes freely through the membrane wall causing no problem in ion chromatographic analysis. Decomposition efficiency is above 99.99% at a flow rate of 0.4mL/min for a 30% hydrogen peroxide concentration. Analytes are quantitatively retained. The analysis results for several brands of commercial hydrogen peroxides are reported.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.481-485
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• 2012

ZnO nanowires were synthesized by hydrothermal technique. Prepared synthesis aqueous solutions were preserved by preheating in autoclave type synthesis equipment with various preheating time of 1 h difference. ITO-coated corning glass substrates deposited with AZO seed layers were then inserted in the preheated synthesis aqueous solutions and ZnO nanowires were grown for 180 min at $90^{\circ}C$. Density, length and aspect ratio of the grown ZnO nanowires were investigated. Composition, structural and optical properties of the grown ZnO nanowires were analyzed. Characteristics of the ZnO nanowires were comparatively studied in relation with $Zn^{2+}$ ion concentration measured directly after the preheating of synthesis aqueous solution.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.94-97
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• 1989

It is shown that fundamental plasma characteristic, which are sheath voltage and ion concentration, can be derived from measuring RF impedence. Plasma characteristics from this simple method are verified by direct measuring, to be reasonable. Using these values a new relation between isotropy and the ratio of sheath voltage to ion concentration is derived. For etch in which $CF_4$ is used, anisotropic etch can be achieved in its order $10^{-12}Vcm^3$ and isotropic etch in $10^{-12}Vcm^3$. These results are useful in every asymetric diode type etch system.