• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.389-396
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• 2008

The purpose of this study was to evaluate the color stability of resin cements with accelerated test. Four dual curing resin cements: Panavia-F (KURARAY). Duolink (BISCO), Variolink-II (Ivoclar Vivadent), and RelyX Unicem (3M ESPE) and 1 self curing resin cement: Resiment CE (j. l. Blosser) were used in this study. In control group, Gradia Anterior (GC) composite resin and Tescera Dentin (Bisco) indirect composite were used. Ten disk shape specimens were made from each resin cement. The specimens were subjected to an accelerated aging process in a refrigerated bath circulator at 60$^{\circ}C$ for 15 and 30 days. Spectrophotometric analyses were made before and after 15 days and 30 days of accelerated aging time. The color characteristics ($L^*,\;a^*,\;b^*$) and the color difference (${\Delta}E^*$) of the specimens before and after immersion were measured and computed. Regardless of type of the resin cements, $L^*$ value was decreased and $a^*$ value was increased, but there were no significant difference. But $b^*$ value was increased significantly (p < 0.05). Tescera inlay showed least color change (p < 0.05), but Gradia showed notable color change after 15 days. After 30 days on accelerated aging, ${\Delta}E^*$ value was increased (Panavia-F < Variolink-II < Resiment CE < Duolink < Unicem) (p < 0.05). but there were no significant difference among Panavia-F, Variolink-II, and Resiment CE groups. After 30 days of accelerated aging, ${\Delta}E^*$ value of all resin cements were greater than 3.0 and could be perceived by the human eye.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.170-177
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• 2019

The aim of this study was to investigate the effect of different concentrations of chlorine dioxide ($ClO_2$) on sterilization and deodorization of food-holding cabinets under different exposure times. For the measuring sterilization and deodorization, a 6.5 L chamber and a 625 L cabinet with circulation systems were used. Two bacteria (Staphylococcus aureus KCTC1916 and Escherichia coli KCTC 1682) that were artificially inoculated in the plate respectively were put into the 6.5 L chamber and the 625 L cabinet. The $ClO_2$ gas was produced by ampules. In the 6.5 L chamber, neither of the two bacteria was detected after 24 hours treatment by $ClO_2$ gas. Moreover, the deodorization rate against ammonia and phenol was 94% and 70%, respectively, but deodorization against formaldehyde was not effective. When the concentration reached maximum (6 ampule, 4.6 ppm) levels in the cabinet, it lasted for approximately 2 h and then decreased slowly. When a circulator was used, the gas concentration was very low (6 ampule, 0.8 ppm) and the antibacterial activity against S. aureus and E. coli was low. The level of reduction against S. aureus and E. coli was 2.98 log CFU/plate and 6.06 log CFU/plate, respectively, in the cabinet after 24 h without a circulator. The reduction against S. aureus KCTC1916 and E. coli KCTC1682 was 2.69 log CFU/plate and 4.41 log CFU/plate for 24 h, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.4
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• pp.267-272
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• 2007

Various kinds of RI wastes are discharged from licensed organizations of radioisotopes les such as hospitals and clinic organizations, educational organizations, research institutions, and public organizations. Radioiodines such as $^{125}I\;and\;^{131}I$ are radioisotopes mainly used in nuclear medicine and industry. A method for the determination of radioiodines in RI wastes has been applied to measure low level activity using acid decomposition method and HPGe gamma ray spectrometer. Prior to analysis of real samples, $^{131}I$ reference solution and 10 g of yellow tissue paper was added to flask in mantle and was heated in 100 mL of 0.4 N $K_2Cr_2O_7$ and 100 mL of 9 M $H_2SO_4$, and then distilled after adding 10 mL of 30% $H_2PO_3$ and 1 mL of 30% $H_2O_2$. The condensed iodine by circulator was extracted into $CCl_4$, then back-extracted into the aqueous phase with 10 mL of 5% $K_2SO_2$ solution. Finally, $^{131}I$ was measured at 364.48 keV using HPGe gamma ray spectrometer after precipitation and filtration. Chemical yield of three steps such as acid decomposition process, chemical separation process, and precipitation and filtration process was more han 94% respectively, MDA(Minimum Detectable Activity) of $^{131}I$ at this analytical condition was 0.6 Bq/g.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.131-137
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• 2013

The thin insulator films for organic memory device were made by the plasma polymerization method using the styrene monomer which was not the wet process but the dry process. For the formation of stable plasma, we make an effort for controlling the monomer with bubbler and circulator system. The thickness of plasma polymerized styrene insulator layer was 430 nm, the thickness of the Au memory layer was 7 nm thickness of plasma polymerized styrene tunneling layer was 30, 60 nm, the thickness of pentacene active layer was 40 nm, the thickness of source and drain electrodes were 50 nm. The I-V characteristics of fabricated memory device got the hysteresis voltage of 45 V at 40/-40 V double sweep measuring conditions. If it compared with the results of previous paper which was the organic memory with the plasma polymerized MMA insulation thin film, this result was greater than 18 V, the improving ratio is 60%. From the paper, styrene indicated a good charge trapping characteristics better than MMA. In the future, we expect to make the organic memory device with plasma polymerized styrene as the memory thin film.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.389-398
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• 2011

In this paper, the design and fabrication of a transmit/receive(T/R) module for Ka-band phased array radar is presented. A 5bit digital phase shifter and digital attenuator were used in common for both transmitter and receiver considering unique Ka-band characteristic. The circulator was excluded in the T/R module and was placed outside T/R module. The transmitting power per element antenna is designed to be about 1 W and the noise figure is designed to be below 8 dB. The designed T/R module RF part has a compact size of $5\;mm{\times}4\;mm{\times}57\;mm$. In order to implement the T/R module, MMICs used in T/R module was separately assessed before assembly of the designed T/R module. The transmitter of the fabricated T/R module shows about 1 W at 5 dBm unit module input power and the receiver shows a gain of about 20 dB and a noise figure of below 8 dB as expected in the design stage.

• Journal of the Korean Magnetics Society
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• v.5 no.2
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• pp.128-133
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• 1995

Yttrium Iron Garnet($Y_{3}Fe_{5)O_{12}$) films have been succsssfully grown on(111)GGG wafer by KrF excimer laser ablation of stoichiometric garnet target at the oxygen partial pressure, $P(O_{2}$, ranging 20 to 500 mTorr. During the deposition of the films the substrate temperature was maintained at $700^{\circ}C$ and the laser beam energy density at $7.75\;J/cm_{2}$. Microstructure, composition and magnetic properties of the films obtained were investigated as a function of oxygen pressure and thickness of the films. Epitaxial films with a dense and a smooth surface were reproducible at a low oxygen pressure. The films of $2.75\;{\mu}$ min thickness deposited at 20 mTorr of $P(O_{2})$ showed $4{\pi}M_{s}$ of 1500 Gauss and $H_{c}$ of 3 Oe after annealing at $800\;^{\circ}C$ for 20 minutes. As-deposited films of $0.8\;\mu\textrm{m}$ in thickness exhibited the $4{\pi}M_{s}$ of 1730 Gauss and $H_{c}$ of 7 Oe. The magnetic properties of the films obtained were almost identical to those of a single crystal YIG.