• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.575-580
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• 2011

It was investigated into the effects on zinc corrosion of the rotation speed of Zn-RDE and the oxygen concentration in borate buffer solution. Zinc corrosion was heavily influenced on the rotation speed of electrode and the oxygen concentration. We have suggested the disproportion reaction following the reversible one electron transfer as the corrosion mechanism of zinc.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.125-130
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• 2000

Two step growth of reduced pressure chemical vapor eposition has been successfully developed to achieve in-situ phosphorus-doped silicon epilayers, and the characteristic evolution on their microstructures has been investigated using scanning electron microscopy, transmission electron microscopy, and secondary ion mass spectroscopy. The two step growth, which employs heavily in-situ P doped silicon buffer layer grown at low temperature, proposes crucial advantages in manipulating crystal structures of in-situ phosphorus doped silicon. In particular, our experimental results showed that with annealing of the heavily P doped silicon buffer layers, high-quality epitaxial silicon layers grew on it. the heavily doped phosphorus in buffer layers introduces into native oxide and plays an important role in promoting the dispersion of native oxides. Furthermore, the phosphorus doping concentration remains uniform depth distribution in high quality single crystalline Si films obtained by the two step growth.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1483-1486
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• 1999

The contents of pentachlorophenol (PCP) and 2,3,5,6-tetrachlorophenol (TeCP) in textile products are regulated for safety. Since an organic solvent such as 2-methoxyethanol is needed to extract chlorinated phenols from textile samples, nonaqueous capillary electrophoresis has been applied to achieve the separation of PCP and isomers of TeCP. The run buffer was 100 mM Tris/acetate in methanol whose pH was adjusted to 8.0. All of the analytes were negatively charged at pH 8.0 and their electrophoretic velocities were higher than the electroosmotic flow of the methanol buffer. A reverse voltage of -20 kV was applied along a 27-cm fused silica capillary with ID of 50 μm, and PCP and 3 TeCP isomers were separated based on the difference in $pK_a$ values in less than 4 min. The limits of detection (S/N = 3) were about 0.02 μM. By varying pH of the methanol run buffer, $pK_a$ values of the 4 chlorinated phenols were also estimated.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.277.1-277.1
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• 2013

Molecular diagnostics consists of three processes, which are a sample pretreatment, a nucleic acid amplification, and an amplicon detection. Among three components, sample pretreatment is an important process in that it can increase the limit of detection by purifying nucleic acid in biological sample from contaminants that may interfere with the downstream genetic analysis such as nucleic acid amplification and detection. To achieve point-of-care virus detection system, the sample pretreatment process needs to be simple, rapid, and automatic. However, the commercial RNA extraction kits such as Rneasy (Qiagen) or MagnaPure (Roche) kit are highly labor-intensive and time-consuming due to numerous manual steps, and so it is not adequate for the on-site sample preparation. Herein, we have developed a rotary microfluidic system to extract and purify the RNA without necessity of external mechanical syringe pumps to allow flow control using microfluidic technology. We designed three reservoirs for sample, washing buffer, and elution buffer which were connected with different dimensional microfluidic channels. By controlling RPM, we could dispense a RNA sample solution, a washing buffer, and an elution buffer successively, so that the RNA was captured in the sol-gel solid phase, purified, and eluted in the downstream. Such a novel rotary sample preparation system eliminates some complicated hardwares and human intervention providing the opportunity to construct a fully integrated genetic analysis microsystem.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.385-385
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• 2009

• Journal of Life Science
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• v.8 no.2
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• pp.197-202
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• 1998

The cell of Kluyveromyces fragilis yeast, which is worthy of an algal substitute, was disrupted by a chemical treatment to increase the digestion of filter-feeders that yeasts are fed to. The optimum conditions of the chemical treatment were obtained by incubating yeasts at 3$0^{\circ}C$ for one hour after treated by 1 M of Na$_{2}$-EDTA that was dissolved in 0.2 M of Tris-buffer and by 0.3 m of 2-mercaptoethanol. The percentage of protop[last production was about 30%. The percentage could be doubled by the pretreatment of three times of 30 seconds sonication.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.400-403
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• 2012

$Cu_2ZnSnSe_4$(CZTSe) is emerged as a promising material for thin-film solar cells because of non-toxic, inexpensive and earth abundant more than $Cu(In,Ga)Se_2$ materials. For fabricating compound semiconductor thin-film solar cells, CdS is widely used for a buffer layer which fabricated by a chemical bath deposition method (CBD). Through the experiment, we controlled deposition temperature and mol ratio of solution conditions to find the proper grain 크기 and exact composition. The optimum CdS layers were characterized in terms of surface morphology by using a scanning electron microscope (SEM) and atomic force microscope (AFM). The optimized CdS layer process was applied on CZTSe thin-films. The thickness of buffer layer related with device performance of solar cells which controlled by deposition time. Local surface potential of CdS/CZTSe thin-films was investigated by Kelvin probe force microscopy (KPFM). From these results, we can deduce local electric properties with different thickness of buffer layer on CZTSe thin-films. Therefore, we investigated the effect of CdS buffer layer thickness on the CZTSe thin-films for decreasing device losses. From this study, we can suggest buffer layer thickness which contributes to efficiencies and device performance of CZTSe thin-film solar cells.

• Korean Journal of Materials Research
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• v.11 no.7
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• pp.575-579
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• 2001

GaN buffer layer and epilayer have been grown on sapphire (0001) by metal organic chemical vapor deposition (MOCVD). GaN buffer layer ranging from 26 nm to 130 nm in thickness was grown at 55$0^{\circ}C$ prior to the 4 $\mu\textrm{m}$ thick GaN epitaxial deposition at 110$0^{\circ}C$. After GaN buffer layer growth, buffer layer surface was examined by atomic force microscopy (AFM). As the thickness of GaN buffer layer was increased, surface morphology of GaN epilayer was investigated by scanning electron microscopy (SEM). Double crystal X-ray diffraction (DCXRD) and Raman spectroscopy were employed to study crystallinity of GaN epilayers. Optical properties of GaN epilayers were measured by photoluminescence (PL). The epilayer grown with a thin buffer layer had rough surface, and the epilayer grown with a thick buffer layer had mirror-like surface of epilayer. Although the stress on the latter was larger than on the former, its crystallinity was much better. These results imply that the internal free energy is decreased in case of the thick buffer layer. Decrease in internal free energy promotes the lateral growth of the GaN film, which results in the smoother surface and better crystallinity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.1
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• pp.47-53
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• 2003

An experimental study on the chromatographic separation of maltopentaose from a mixture, including glucose, maltose, maltotriose, and maltopentaose, was carried out in a nonionic polymeric sorbent column while varying the operating conditions, such as the solution pH, buffer contents, and isopropyl alcohol (1PA) concentration. Unlike the pH and buffer contents, the IPA concentration had a Significant impact on the single component chromatograms for maltopentaose. The retention times of the maltooligosaccharides with the nonionic polymeric sorbent Sp207 were in the following order: glucose < maltose < maltotriose < maltopentaose. From the experimental binary, ternary, and quaternary chromatograms, gradient chromatographic separation with a changing IPA concentration as a function of time was required to obtain high-purity maltopentaose and reduce the elution time.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.1-4
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• 2015

Production of $MgB_2$ film on metallic Hastelloy with SiC as the buffer layer was achieved by means of hybrid physical-chemical vapor deposition technique, whereas SiC buffer layers with varied thickness of 170 and 250 nm were fabricated inside a pulsed laser deposition chamber. Superconducting transition temperature and critical current density were verified by transport and magnetic measurement, respectively. With SiC buffer layer, the reduced delaminated area at the interface of $MgB_2$-Hastelloy and the slightly increased $T_c$ of $MgB_2$ tapes were clearly noticed. It was found that the upper critical field, the irreversibility field and the critical current density were reduced when $MgB_2$ tapes were buffered with SiC buffer layer. Clarifying the mechanism of SiC buffer layer in $MgB_2$ tape in affecting the superconducting properties is considerably important for practical applications.