• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.637-643
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• 2003

In order to improve the photoluminescent properties and crystallinity, Zn$_2$SiO$_4$:Mn, M(M=Cr, Ti) phosphors were synthesized by the sol-gel method. The willemite single phase was obtained at 110$0^{\circ}C$, which is lower temperature than that of the conventional solid-state reaction (130$0^{\circ}C$). The characteristics of fired samples were obtained by a 147 nm excitation source under VUV (Vacuum Ultraviolet). To investigation the effect of co-dopant, the content of Mn and the ratio of $H_2O$ to TEOS was fixed as 2 ㏖% and 36. 1, respectively. The highest emission intensity was obtained when the concentration of Cr and Ti was 0.1 ㏖% relative to Zn$_2$SiO$_4$:Mn. While the emission intensity decrease continuously the decay time improved as increased the Cr concentration. In the case of Ti added samples, however, the emission intensity increase up to 2 ㏖％ concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.182-182
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• 1999

The chemisorption effect of CO on the Ni/Cu(001) surface was investigated using LEED(Low Energy Electron Diffraction) and EELS(Electron Energy Loss Spectrscopy0 under the UHV conditions. after mounting the Cu(001) single crystal in the UHV chamber (base pressure 1$\times$10-10Torr), a clean surface was obtained after a few cycles of repeated Ar+ ion sputtering and annealing at about 40$0^{\circ}C$. The epitaxial thin Ni films were formed on the Cu(001) by evaporation from 99.999% Ni block. The pseudomorphic growth and the orderness of the thin Ni films were monitored by c(2$^{\circ}C$2) LEED pattern. CO adlayers on Ni epitaxial thin films were prepared by dosing pure CO has through a leak valve. After CO adsorpton at room temperature, two pairs of peaks were observed by EELS, whose relative intensities are changed as the film thickness is varied and time is elapsed. These two pair of peaks are likely related to different bonding sites (-top and bridge sites) of C-Ni as well as C-O vibration. Experimental results and qualitative interpretation of the spectra wille be discussed. The possibility of using EELS in combination with probe species (CO) to investigate the nature of thin film growth is mentioned. We will report the experimental result of O2 dosage on Ni film and interaction of CO and O2.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.283-283
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• 2011

The n-doping effect by doping metal carbonate into an electron-injecting organic layer can improve the device performance by the balanced carrier injection because an electron ohmic contact between cathode and an electron-transporting layer, for example, a high current density, a high efficiency, a high luminance, and a low power consumption. In the study, first, we investigated an electron-ohmic property of electron-only device, which has a ITO/$Rb_2CO_3$-doped $C_{60}$/Al structure. Second, we examined the I-V-L characteristics of all-ohmic OLEDs, which are glass/ITO/$MoO_x$-doped NPB (25%, 5 nm)/NPB (63 nm)/$Alq_3$ (32 nm)/$Rb_2CO_3$-doped $C_{60}$(y%, 10 nm)/Al. The $MoO_x$doped NPB and $Rb_2CO_3$-doped fullerene layer were used as the hole-ohmic contact and electron-ohmic contact layer in all-ohmic OLEDs, respectively, Third, the electronic structure of the $Rb_2CO_3$-doped $C_{60}$-doped interfaces were investigated by analyzing photoemission properties, such as x-ray photoemission spectroscopy (XPS), Ultraviolet Photoemission spectroscopy (UPS), and Near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, as a doping concentration at the interfaces of $Rb_2CO_3$-doped fullerene are changed. Finally, the correlation between the device performance in all ohmic devices and the interfacial property of the $Rb_2CO_3$-doped $C_{60}$ thin film was discussed with an energy band diagram.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.506-511
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• 2006

ZnO nanorods were prepared by the hydrothermal reaction of a solution containing $Zn(NO_3)_2{\cdot}6H_2O$, NaOH, cyclohexylamine, ethanol and water, and their $NO_2$ and CO sensing behaviors were investigated. By the control of water concentration in solution, the morphology and agglomeration of ZnO nanorods could be manipulated, which is associated with the variation of $[OH^-]$ resulted from an interaction between water and cyclohexylamine. Sea-urchin-like and well-dispersed ZnO nanorods were prepared at low and high water content, respectively. Well-dispersed ZnO nanorods showed 1.8 fold change in resistance at 1 ppm $NO_2$ while there was no significant change in resistance at 50 ppm CO. This selective detection of $NO_2$ in the presence of CO can be used in automated car ventilation systems.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.152-160
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• 1993

In this study, we have investigated the influence of sputtering conditions (Ar pressure input powers, substrates) on coercivity and microstructures of GdFe, Co, CoCr thin films produced by the method of DC magnetron sputtering. In GdFe films, we have observed that the Gd atomic ratio was decreased with the deposition rate, and deposition rate decreased with the pressure of Ar gas and the increased linearly with input power. It was also observed that the coercivity of thin films was increased with input power. In Co films, we have investigated the deposition was increased and the Co thin film became finer structure with the increase in the input power, was increased and the Co thin film became finer structure with the increase in the input power, and the deposition rate was decreased with the pressure of Ar gas. In CoCr films, we have investigated the effects of substrates on the coercivity $(H_c)$ and the microstructure. We have found that the substrates plays a crucial role in the microstructure and the coercivity $(H_c)$.

• Korean Journal of Poultry Science
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• v.17 no.3
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• pp.203-209
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• 1990

This study was carried out to investigate the effects of packaging methods on the shelf-life of refrigerated chicken parts at $4^{\circ}C$. The microbial and physicochemical changes of chicken parts during storage periods were also examined to determine the shelf-life. The shelf-life of chicken parts dipped in 7.5% potassium sorbate with different packaging methods such as conventional packaging, vacuum packaging and modified atmosphere packaging was determined. The shelf-life of conventional packaged chicken parts dipped in 7.5% potassium was $19\pm3$ days and the shelf-life of vacuum packaged chicken parts dipped in 7.5% potassium sorbate was $30\pm5$ days. The shelf-life of 10% $CO_2$ and 90% $N_2$ gas contained packaged chicken parts dipped in 7.5% potassium sorbate was $26\pm4$ days while 20% $CO_2$ and 80% $N_2$ gas contained packaged chicken parts dipped in 7.5% potassium sorbate was $30\pm5$ days.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.16-21
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• 2001

Optical properties of $Ag_2CdSnSe_4$ and $Ag_2CdSnSe_4:Co^{+2}$ quaternary semiconductor single crystals grown by the chemical transport reaction method were investigated. The analysis of the X - ray powder diffraction measurements showed that these crystals have a wurtzite structure with lattice constants a = 4.357 $\AA$, c = 7.380 $\AA$, for $Ag_2CdSnSe_4$ and a = 4.885 $\AA$, c = 7.374 $\AA$, for $Ag_2CdSnSe_4:CO^{2+}$. The direct band gap at 298K, obtained from the optical absorption measurement, is found to be 1.21 eV for $Ag_2CdSnSe_4$ and 1.02 eV for $Ag_2CdSnSe_4:CO^{2+}$. The shrinkage of the band gap due to Co-doping is observed and is about 190 meV, We observed four absorption bands of $Co^{2+}$ ions in two near infrared regions of optical absorption spectra of $Ag_2CdSnSe_4$:$Co^{+2}$. These absorption bands were assigned as due to electronic transitions between the split energy levels of $Co^{2+}$ ions in $T_d$ crystal field under spin-orbit interactions.

• Preventive Nutrition and Food Science
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• v.8 no.2
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• pp.196-199
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• 2003

We investigated the antagonistic effects of two lactococcal bacteriocins, nisin or lacticin NK24, on the growth and the survival of Listeria monocytogenes in vacuum or modified atmosphere-packaged ground beef, Ground beef was inoculated with approximately 3 log colony-forming units (CFU) of L. monocytogenes ATCC 15313 culture per gram of ground beef. Inoculated samples were blended with/without 100 AU/g nisin or lacticin NK24, and subsequently vacuum or modified atmosphere packed at 4$^{\circ}C$. Listeria in the bacteriocin-treated and control samples was subsequently isolated from both vacuum and modified atmosphere packs and enumerated as CFU on Listeria Isolation Agar medium. Microbial counts in ground beef treated with bacteriocin declined steadily, while those of non-treated beef samples increased steadily. The results obtained demonstrate that nisin inhibits the growth of L. monocytogenes more effectively than lacticin NK24 at 100 AU/g. The use of lactococcal bacteriocins, such as nisin or lacticin NK24, in vacuum or modified atmosphere packaging offers a promising approach for eliminating or reducing the risk of L monocytogenes contamination in ground beef.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.339.1-339.1
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• 2014

In this paper we studied the application of inter-poly dielectric as silicon dioxide-like film was deposited by the higher energy assisting deposition (HEAD) process the modified CCP process, which enables low temperature (LT) process and improving film density. In these experiments the relative hydrogen concentration of $SiO_2$-like films deposited on silicon substrate were analyzed by the secondary ion mass spectroscopy (SIMS) and it was shown that our lower hydrogenated oxide (LHO) film prepared by HEAD process with the precursor contained the siloxane species had lower hydrogen concentration, $8{\times}10{\cdot}^{22}cm{\cdot}^3$ than that of the commercial undoped silicon glass (USG) film ($1{\times}10{\cdot}^{21}cm{\cdot}^3$) prepared by the high density plasma-chemical vapor deposition (HDP-CVD). We consider that the LHO film deposited by HEAD process used as high performance material into Flash memory devices.

• Elastomers and Composites
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• v.20 no.2
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• pp.115-131
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• 1985

Heavy residual fuel oils is a mixture of reduced crude from crude unit, bottom products from vacuum and/or catalytic cracking unit with distillate to meet the specification and generally used as heavy fuel oil for large combustion engines, boilers, etc$\cdots$. But this study was made to investigate heavy residual fuel oils for using as industrial raw material and resulted the following possiblities as valuable raw material as well as heavy fuel oil. 1) Production of straight asphalt through vacuum distillation unit. 2) Using straight asphalt from vacuum distillation unit for manufacturing of blown asphalts, cut back asphalts, emulsified asphalts and asphalt compound, rubber/asphalt sheet, etc$\cdots$. 3) Using waxy oil side streams for manufacturing of raw oil to be lube oil base stocks through solvent dewaxing. 4) Production of lube base oils and rubber process oils from dewaxed raw oil through chemical treatments. 5) Manufacturing of paraffine wax from slack wax to be produced as by product of dewaxing process.