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Optimization of VUV Characteristics of M3MgSi2O8:Eu2+ (M=Ca, Sr, Ba) Phosphor by Spray Pyrolysis (분무열분해법을 이용하여 M3MgSi2O8:Eu2+ (M=Ca, Sr, Ba) 형광체 분말의 VUV 특성 최적화)

  • Jung, You-Ri;Jung, Kyeong-Youl
    • Journal of Powder Materials
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    • v.15 no.5
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    • pp.399-404
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    • 2008
  • Spray pyrolysis was applied to prepare $M_{3}MgSi_{2}O_{8}:Eu^{2+}$ (M=Ca, Sr, Ba) blue phosphor powder. The library of a Ca-Sr-Ba ternary system was obtained by a combinatorial method combined with the spray pyrolysis in order to optimize the luminescent property under vacuum ultraviolet (VUV) excitation. 10 potential compositions were chosen from the first screening. The emission shifted to longer wavelength as Ca became a dominant element and the emission intensity was greatly reduced in the composition region at which Ba is dominant element. On the base of the first screening result, the second fine tuning was carried out in order to optimize the luminescence intensity under VUV excitation. The optimal composition for the highest luminescence intensity was $(Ca_{1.7},\;Sr_{0.3},\;Ba_{1.0})Si_{2}O_{8}:Eu^{2+}$ which had the color coordinate of (0.152, 0.072) and about 64% emission intensity of $BaMgAl_{10}O_{17}$ (BAM) phosphor.

Image Encryption using Shrinking Generator based on CA (CA기반의 수축생성기를 이용한 영상 암호)

  • Choi, Un-Sook;Cho, Sung-Jin;Kim, Han-Doo;Kang, Sung-Won
    • The Journal of the Korea institute of electronic communication sciences
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    • v.15 no.1
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    • pp.179-184
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    • 2020
  • Cellular automata (CA), which is known as a pseudo random number generator due to its excellent randomness, has various applications. Cho et al. designed a CA-based shrinking generator to generate a long period of nonlinear sequence. In addition, chaotic cat maps have been studied by many researchers as the complex nonlinear dynamics systems with sensitivity in initial conditions and unpredictable characteristics. In this paper, we propose a new image encryption method using nonlinear sequence generated by CA-based shrinking generator with maximum period and 3D chaotic cat map for high security.

Study on the Dispersion Stability of Precipitated Calcium Carbonate Suspensions (침강성 탄산칼슘 현탁액의 분산 안정성에 관한 연구)

  • Park, Myung-Jae;Ahn, Ji-Whan;Kim, Hwan
    • Journal of the Korean Ceramic Society
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    • v.38 no.4
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    • pp.343-350
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    • 2001
  • 본 연구에서는 탄산화법으로 침강성 CaCO$_3$분말을 제조하고 제조된 CaCO$_3$현탁액의 분산안정성을 연구하였다. CaCO$_3$현탁액의 pH 변화와 고분자전해질 PMAA와 PAA의 첨가에 따른 입자크기, 유동학적 특성(점도), zeta potential 및 현탁액의 침강속도 등을 측정하였다. 탄산화법에 의해 약 0.1$\mu\textrm{m}$ 크기와 비표면적이 23.57$m^2$/g인 단분단 calcite형 CaCO$_3$분말을 제조하였다. pH가 11인 CaCO$_3$현탁액에 0.01 wt% PMAA가 첨가된 경우에 우수한 분산안정성을 나타내었는데 이는 CaCO$_3$입자표면에 PMAA의 흡착에 의한 electrosteric 안정화기구와 CaCO$_3$입자들 사이의 정전기적 반발력에 의한 것으로 판단된다. PMAA와 PAA 첨가량 변화에 따른 pH 6, 9, 11의 CaCO$_3$현탁액의 침전높이를 측정한 결과 PMAA와 PAA의 농도가 0.15 wt% 부근에서 분산안정성을 보였는데 이는 CaCO$_3$입자들 사이간의 분산제에 의한 뚜렷한 경계를 갖는 흡착층이 형성되었기 때문으로 생각되며 따라서 CaCO$_3$현탁액의 최적 분산안정성을 위해서는 적절한 pH 조절과 PMAA 및 PAA의 첨가가 필요함을 알 수 있다.

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Float Zone Growth of Superconduction $Bi_2Sr_2CaCu_2O_8$ Fiber with Halogen Lamp (할로겐 램프 열원을 이용한 초전도성 $Bi_2Sr_2CaCu_2O_8$ Fiber의 Float Zone 성장)

  • 김철진;정준기
    • Korean Journal of Crystallography
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    • v.7 no.2
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    • pp.147-155
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    • 1996
  • Floating Zone Image furnace with halogen lamps as heat source has been made and applied to the growth of high-Tc superconductor Bi2Sr2CaCu2O8. The manufactured crystal growth equipment is composed of holder unit for setting the halogen lamps at the focal point of the elliptical mirror, image furnace with maximum temperature of 1800℃ with 1kW halogen lamps, cooling unit, feeding unit for supplying source material to the molten zone, pulling unit for crystal growth, and the control unit in the range of 2mm/hr -40 mm/hr vertical movement and 15rpm - 12rpm rotation. Bi2Sr2CaCu2O8 fibers have been grown with 300W halogen lamps and characterized with XRD, SEM and EDS. The growth condition was air atmosphere, growth speed 3∼4mm/hr, rotation speed of upper and lower part 20∼25 rpm. The fiber was composed of 20∼25 rpm matrix phase and secondary phases such as (Sr,Ca)CuO2 and (Sr,Ca)2CuO3.

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Effects of Lime and NPK Application Rates on the Soil Charateristics after a 10-year Experiment in Oversown Hilly Pasture of Mixed Grass-Clover Sward III. Change in the mutural ratios of exchaegeable cations by the soil depth, and the visible characteristics of soil conservation (겉뿌림 산지초지에서 석회 및 3요소 시용수준이 10년후 토양특성에 미치는 영향 III. 토심별 염기간 상호비율 및 가시적 토양보존의 특성변화)

  • 정연규;이혁호
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.18 no.3
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    • pp.223-232
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    • 1998
  • The main experiment related to this report was undertaken to assess the effects of two rates of $Ca(OH)_2$ (0, 250 kg/10a only at establishment) and five rates of $N-P_20_5-K_20$ (0-0-0, 0-10-10, 6-15-15, 12-20-20, 24-25-20 kg/10a/year) on the pasture establishment, forage yield and quality, and vegetation etc. After this 10-year main e experiment pasture had been used to assess the effects of the above treaments on the soil characteristics in oversown hilly pasture of a grass-clover sward. soil properties of mutual ratios of exchangeable cations at d different soil depth, and the visible characteristics of soil conservation obtained are summarized as follows; 1. Compared with the properties of soil fertility and the level for the likelihood grass tetany, the mutual ratios of exchangeable cations in soils; Ca:Mg:K(% of CEC), Ca:Mg:K(K=I), $K/\sqrt{Ca+Mg}$, Mg/K, K/Mg, and Ca/Mg, were discussed at different soil depth. Before and after experiment, these ratios were generally unbalance and unsuitable, and were rather worsened in the order of Mg>Ca>K under the conditions of liming and NPK fertilization without Mg. 2. The ratios of Ca and Ca/Mg were increaby liming, whereas it of $K/\sqrt{Ca+Mg}$ was redused. The ratios of K and $K/\sqrt{Ca+Mg}$ in control and the heavy fertillization of NPK(especially N) were rather lowered than those in the low and medium fertilizations of NPK. 3. The prperties of consevation were closely related with the forage productivity/vegetation rates, as affected by liming and the application rates of NPK. In control of NPK, It was shown to be the worst soil conservation; severly eroded(3rd grade), exporsure of subsoil, redish brown in soil colour, and 18.8% of cobble and stony in covering rate. 4. The improvement of soil conservation was greatly enhanced by increasing the NPK rate. In the medium and heavy fertilizations of NPK, it was shown to be the favorable improvement of soil conservation; slightly eroded(lst grade), covered with humus layer/grass residues in surface soil, dark brown in surface soil colour, under 1% of cobble and stony in covering rate. The increasing of legume yield/vegetation rate by liming rather enhanced the soil conservation of grassland.

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Studies on the Preserving Method for Inhibiting Feed Degradation (사료변질 방지를 위한 보존방법에 관한 연구)

  • 김대진;방극승;김영길;최경문;김진성
    • Korean Journal of Poultry Science
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    • v.8 no.1
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    • pp.7-14
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    • 1981
  • The experiment using Anake broiler strain chicks was conducted to study the effort fungistatic agents on microbial counts, Ins of nutrient, growth rate and feed efficiency of the broiler. Feed was adjusted to 12% and 15% moisture level during hot and high humidity season and sorbic acid at the level of 0.02%, 0.04% and Ca-propionic acid at the level 0.1% 0.2% was added. The results obtained were as follows. 1, The Addition of fungistatic agents could slightly reduce mold and yeast counts. The highest effect on inhibition of mold and yeast counts was observed for the addition of sorbic acid at 0.04% level to the fled contained 15% moisture. 2, Approximately 14% starch loss of ground corn was observed from the fred contained 15% moisture and the loss could be diminished to 3-7% by the addition of fungistatic agents with the superior effect of sorbic acid to Ca-propionic acid. 3. Approximately 15% fat loss was detected when high moisture fled was und and this was reduced to 7% by the addition of 0.04% sorbic acid to the feed. 4. Significantly higher growth rate (p<0.05) during starter period was observed for low moisture feed added by sorbic acid compared with that for high moisture diet without fungistatic agents or with Ca-propionate at the level of 0.1%. 5. Significantly lower feed efficiency (p<0.05) during starter period of high moisture feed without fungistatic agents was observed; hower no significant different response was detected by either moisturer level of kinds and levels of fungistatic agents used. 6. Significantly higher growth rate (p<0.05) during finisher period of lower moisture feed with 0.04% sorbic acid was observed compared with that of high moisture fled without fungistatic agents or the feed added by 0.1% Ca-propionate level. 7. Significantly higher feed efficiency (p<0.05) during finisher period of low moisture feed added by sorbic acid 0.02% or 0.04% level was found compared with that of high moisture feed without fungistatic agents and low moisture feed added by Ca-propionate at the level of 0.1% or 0.2%. 8. Mort bacteria, mold and yeast were observed in the ceca than in small intestine. The. moisture content of dict had no effect on intestinal microfloral counts. However, numbers of mold and yeast of intestine could slightly be reduced by fungistatic agents administration. 9. Nothing but encephalomalacia to chicks fed feed contained 15% moisture without addition of fungistatic agents was observed. In conclusion, addition of either sorbid acid at 0.04% level and Ca-propionate at 0.2% level to high moisture feed or reduced moisture level to 12% could be con-sidered more effective to enhance growth rate and fled efficiency of broilers during summer period.

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The Hydration of Hardenced Flyash-$Ca(OH)_2-CaSO_4$.$2H_2O$ System (Flyash-$Ca(OH)_2-CaSO_4$.$2H_2O$계의 수화반응)

  • 김창은;이승헌;이상완;김원기
    • Journal of the Korean Ceramic Society
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    • v.23 no.3
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    • pp.27-34
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    • 1986
  • The hydration of flyash-$Ca(OH)_2-CaSO_4$.$2H_2O$ system was stuedied with varing mixing ratio of flyahs $Ca(OH)_2$ and caSO4.2H2O The samples were steam-cured for 1-7 days at 9$0^{\circ}C$. The optimum mixing composition was flyash : Ca (OH)2=65:35 with 15% $CaSO_4$.42H_2O$ added which produced the hardened material having the best compressive strength (300kg/$cm^2$) Also the low specific gravity(1, 2) of the hardened paste suggests the possibility that it can be used as a light-weight building material. The added $CaSO_4$.42H_2O$ constituted calcium-sulfo-aluminate hydrates which activates the formation of C-S-H hy-drates. Both hydrates developed the strength of hardened paste. The amount of calcium-sulfo-aluminate hydrates was increased when the $CaSO_4$.42H_2O$ was added over 15% however the increased amount did not help the development of strength because of the individually grown calcium-sulfo-aluminate hydrates.

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DTNB oxidation effects on T-type $Ca^{2+}$ channel isoforms

  • Lee, Sang-Soo;Kang, Ho-Won;Park, Jin-Yong;Lee, Jung-Ha
    • Animal cells and systems
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    • v.15 no.2
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    • pp.131-138
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    • 2011
  • Redox regulation is one of the ubiquitous mechanisms to modulate ion channels. We here investigated how 5,5'-dithio-bis (2-nitrobenzoic acid), a cysteine specific oxidizing reagent, modulates $Ca_v3.1$ and $Ca_v3.2$ T-type $Ca^{2+}$ channels expressed in Xenopus oocytes. Application of the reagent inhibited $Ca_v3.1$ and $Ca_v3.2$ currents in a dose-dependent manner. The oxidizing reagent (1 mM) reduced the peak amplitude of $Ca_v3.1$ and $Ca_v3.2$ currents by ~50% over 2-3 minutes and the decreased currents were fully recovered upon washout of it. The reagent slowed the activation and inactivation kinetics of $Ca_v3.1$, $Ca_v3.2$, and $Ca_v3.3$ channel currents. Notably, the reagent positively shifted both activation and steady-state inactivation curves of $Ca_v3.1$, while it did not those of $Ca_v3.2$. Utilizing chimeric channels from $Ca_v3.1$ and $Ca_v3.2$, we localized the domains III and IV of $Ca_v3.1$ responsible for the positive shifts of channel activation and steady-state inactivation. These findings provide hints relevant to the electrophysiological and molecular mechanisms accounting for the oxidative regulation of T-type channels.

Effect of $\textrm{Ca}^{2+}$ Concentration on Electric Activation of In Vitro Matured Oocytes of Korean Native Cattle ($\textrm{Ca}^{2+}$ 씨오투 농도가 체외성숙 유래 한우 난자의 전기적 활성화에 미치는 영향)

  • 송길영;이은송;이병천;황우석
    • Journal of Embryo Transfer
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    • v.11 no.3
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    • pp.259-269
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    • 1996
  • The present study was undertaken to examine the critical effect of $Ca^2$+ concentration on electrostimulation and post-electrostimulation media for electric activation of in vitro matured oocytes of Korean Native Cattle. Oocytes collected from slaughterhouse ovaries were matured in TCM 199 containing FSH, estradiol-17$\beta$ and FBS with granulosa cell monolayer for 24 hours and denuded with hyaluronidase. And then cumulus-free oocytes were submitted to a DC field of 1.0 kV/cm for 60 $\mu$sec in electroporation media(0.28 M mannito' and PBS) with different $Ca^2$+ concentations (0.00, 0.05, 0.10 and 0.15 mM). Stimulated oocytes were stained and examined for pronuclear formation after incuhation in SOF for 12 hours. The rates of pronuclear formation in hovine oocytes electrically stimulated in 0.28 M mannitol with 0.05, 0.10 and 0.15 mM $Ca^2$+(60.3, 82.2 and 75.0%) were significantly higher than without $Ca^2$+(6.3%) at 12 hours after an electric pulse(p<0.005). The activation rates of Korean Native Cattle oocytes stimulated in PBS supplemented with 0.05, 0.10 and 0.15 mM $Ca^2$+(71.0, 75.8 and 75.4%) were significantly higher than without $Ca^2$+(23.5%) after post-stimulation incubation(p<0.005). After incubation of oocytes in SOF with and without $Ca^2$+ following electric stimulation in 0.28 M mannitol with 0.10 mM $Ca^2$+, the rates of pronuclear formation of bovine oocytes in $Ca^2$+-free SOF(85.7%) was significantly higher than in SOF with 1.71 mM $Ca^2$+(62.5%, p<0.05). When oocytes were stimulated in two electrostimulation media supplemented with $Ca^2$+ and incubated in $Ca^2$+-free SOF, there were no significant differences in the rates of pronuclear formation hetween 0.28 M mannitol and PBS. These results indicate that a single electric pulse could induce activation of Korea Native Cattle oocytes in 0.28 M mannitol and PBS supplemented with $Ca^2$+. Furthermore, to improve the activation rates, it was hetter that stimulated oocytes were incubated in $Ca^2$+-free SOF after electric stimulation than in SOF with $Ca^2$+.

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