• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.5
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• pp.60-67
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• 2005

The superposed discharge type ozonizer of high ozone concentration using vacuum discharge tube has been designed and manufactured. It consists of three electrodes(central electrode, internal electrode, and external electrode) and one discharge gap(discharge gap between internal electrode and external electrode), is a superposed silent discharge type ozonizer for which the AC high voltages applied to the central electrode within discharge tube and the internal electrode has a $180{[^\circ]}$ phase difference and for which the external electrode is a ground. Ozone is generated by overlapping silent discharge between central electrode and external electrode, and silent discharge between internal electrode and external electrode. At the moment, discharge characteristics and ozone generation characteristics were investigated in accordance with vacuum of discharge tube, discharge power of ozonizer, and quantity of supplied oxygen gas. In consequence, high ozone concentration can be obtained 8840[ppm].

• Journal of Ginseng Research
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• v.23 no.2 s.54
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• pp.88-92
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• 1999

Hydrolysis properties of ginseng saponins in processing of extraction with vacuum impulse system extraction method were compared with multi-stage extraction methods. Crude saponin content of the extract produced by vacuum impulse system extraction method was $11.5\%,$ compared with multi-stage extraction method (about $8.13\%).$ Also the yield of the extract increased about $6.7\%.$ The flavor and aroma of ginseng extract with vacuum impulse system extraction method are stronger than multi-stage extraction methods and people have a tendency to like more. The color was similar to existing extraction items and the liquidity ratio was high. Vacuum impulse system extraction method could save human resources because of short extraction time and automatic operation of processing. With HPLC pattern, We could ascertain the truth that hydrolysis properties of ginseng saponin was restrained in the extraction processing, vacuum impulse system extraction method.

• Korean journal of food and cookery science
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• v.33 no.3
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• pp.316-324
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• 2017

Purpose: Gulbi is a salted and dried yellow corvenia that is popular in Korea. In this study, yellow corvenia was vacuum-dried under two different conditions, average temperatures of $48^{\circ}C$ for 12 and 15 h and $54^{\circ}C$ for 9 and 12 h. Quality characteristics of vacuum-dried Gulbi against fresh corvenia were investigated. Methods: Moisture content, water activity, salt concentration, pH, acidity, volatile basic nitrogen (VBN), thiobarbituric acid-reactive substances (TBARS), and fatty acid composition of Gulbi were evaluated. Results: Moisture contents of fresh corvenia and four types of vacuum-dried Gulbi were 67.37, 31.51, 13.62, 35.17, and 10.05%, respectively. The pH values were in the range of pH 6.70-6.98. The VBN values of Gulbi vacuum-dried at the higher temperature range were greater than those of Gulbi at the lower temperature range. The TBARS of Gulbi increased after vacuum drying (p<0.05). Palmitic acid, palmitoleic acid, oleic acid, and docosahexaenoic acid were the main fatty acids of Gulbi. Conclusion: These results indicate that the quality of vacuum-dried Gulbi is dependent on the drying conditions including temperature and time.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.357-357
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• 2012

The doping process of the solar cell has been used by furnace or laser. But these equipment are so expensive as well as those need high maintenance costs and production costs. The atmospheric pressure plasma doping process can enable to the cost reduction. Moreover the atmospheric pressure plasma can do the selective doping, this means is that the atmospheric pressure plasma regulates the junction depth and doping concentration. In this study, we analysis the atmospheric pressure plasma doping compared to the conventional furnace doping. the single crystal silicon wafer doped with dopant forms a P-N junction by using the atmospheric pressure plasma. We use a P type wafer and it is doped by controlling the plasma process time and concentration of dopant and plasma intensity. We measure the wafer's doping concentration and depth by using Secondary Ion Mass Spectrometry (SIMS), and we use the Hall measurement because of investigating the carrier concentration and sheet resistance. We also analysis the composed element of the surface structure by using X-ray photoelectron spectroscopy (XPS), and we confirm the structure of the doped section by using Scanning electron microscope (SEM), we also generally grasp the carrier life time through using microwave detected photoconductive decay (u-PCD). As the result of experiment, we confirm that the electrical character of the atmospheric pressure plasma doping is similar with the electrical character of the conventional furnace doping.

• Journal of the Korean Vacuum Society
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• v.21 no.2
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• pp.93-98
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• 2012

$Gd_{1-x}VO_4:{Eu_x}^{3+}$ phosphor powders were synthesized with changing the concentration of $Sm^{3+}$ ion by using a solid-state reaction method. The crystal structures of all the phosphors were found to be a tetragonal system, composed of (200) diffraction peak centered at $24.76^{\circ}$, and the morphology of grains approached the spherical form with homeogenous size distribution when the concentration of $Sm^{3+}$ ion was 0.05 mol. As for the photoluminescence properties, all of the phosphor powders, irrespective of $Sm^{3+}$ ion concentration, indicated the yellow, orange, and red emission peaked at 565, 603, and 645 nm respectively. As the concentration of $Sm^{3+}$ ion increases, the intensity of excitation spectrum showed a decreasing tendency on the increase of Sm3+ ion concentration. The maximum excitation and emission spectra were observed and the symmetry ratio was 1.19 at 0.05 mol of $Sm^{3+}$ ion.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.73-78
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• 2009

Zinc Oxide (ZnO) nanorods arrays were deposited on ZnO buffered p-Si(100) substrates by hydrothermal method. The ZnO buffer layer with a thickness of 30 nm was deposited by metal oxide chemical vapor deposition at $500^{\circ}C$. The structural and optical properties of ZnO nanorods arrays controlled by precursor concentrations from 0.06 to 0.5 M were studied by FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), and PL(photoluminescence), respectively. It was found that the structural and optical properties of ZnO nanorods arrays are changed significantly with increase of precursor concentration. The sizes of diameter and length of nanorods were increased as the concentration increase, and good optical property was shown with the concentration of 0.3 M.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.430-435
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• 2011

$Y_{1-x}PO_4:{Eu_x}^{3+}$ red phosphors were synthesized with changing the concentration of $Eu^{3+}$ ion by using a solid-state reaction method. The crystal structures of all the red phosphors were found to be a tetragonal system composed of (200) diffraction peak centered at $25.88^{\circ}$, and the morphology of grains approached the spherical form with homeogenous size distribution as the concentration of $Eu^{3+}$ ion increased. As for the photoluminescence properties, all of the ceramic phosphors, irrespective of $Eu^{3+}$ ion concentration, showed the red-orange and the red emission peaked at 593.0 and 619.2 nm respectively. As the concentration of $Eu^{3+}$ ion increased, the excitation spectrum moved into a longer wavelength with the increase of emission intensity. The maximum excitation and the emission spectrum were observed at 0.15 mol of $Eu^{3+}$ ion.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.39-42
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• 2002

There is a renewed interest in the application of photoconductors especially Cd(Zn)Te to x-ray imaging. In this paper, We investigate effects on x-ray detection characteristic of Zn dopped CdTe detector. Cd(Zn)Te film was fabricated by vacuum thermal evaporation method and then investigate physical analysis using EPMA and XRD. We investigated the leakage current and X-ray photosensitivity as applied voltage about fabricated Cd(Zn)Te film. Experimental results showed that the increase of Zn dopped concentration in $Cd_{1-x}Zn_{x}Te$ detector reduced a leakage current and improved a signal to noise ratio significantly.

• Food Science and Preservation
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• v.4 no.3
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• pp.265-270
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• 1997

Effect of modified atmosphere packaging conditions on quality changes of dry jujube was investigated. Dry jujubes with moisture content of 26.7% were packaged in PET/Al/PE film pouches with modified atmospheres. The tested packages include those with normal air, vacuum, CO2 flushing, N2 flushing and O2 scavenger. Packages were stored at 25$^{\circ}C$ for 6 months, during which ascorbic acid concentration, browning level, titratable acidity and surface color were measured. Generally modified atmosphere packages could improve quality retention of dry jujubes except that vacuum package resulted in large surface color change. CO2-flushed package showed the best quality retention of high ascorbic acid content and low browning during 112 days, but caused high amounts of ascorbic acid destruction and browning in longer storage. In all the modified atmosphere packages titratable acidity reached a maximum followed by decline and subsequent rise, while it increased linearly with time in normal air package. Considering ascorbic acid retention browning level and surface color changes during 112 days, the packages of CO2 flushing and N2 flushing were better than others.