• Korean Journal of Microbiology
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• v.45 no.4
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• pp.411-415
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• 2009

Some microorganisms are capable of leaching Mn(II) from nonsulfidic manganese ores indirectly via nonenzymatic processes. Such reductive dissolution requires organic substrates, such as glucose, sucrose, or galactose, as a source of carbon and energy for microbial growth. This study investigated characteristics of Mn(II) leaching from manganese nodules by using heterotrophic Bacillus sp. strain MR2 provided with corn starch as a less-expensive substrate. Leaching of Mn(II) at 25.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$ was accompanied with cell growth, but part of the produced Mn(II) re-adsorbed onto residual $MnO_2$ particles after 24 h. Direct contact of cells to manganese nodule was not necessary as a separation between them with a dialysis tube produced similar amount [24.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$]. These results indicated an involvement of extracellular diffusible compound(s) during Mn(II) leaching by strain MR2. In order to optimize a leaching process we tested factors that influence the reaction, and the most efficient conditions were $25\sim35^{\circ}C$, pH 5~7, inoculum density of 1.5~2.5% (v/v), pulp density of 2~3 g/L, and particle size <75 ${\mu}m$. Although Mn(II) leaching was enhanced as particle size decrease, we suggest <212 ${\mu}m$ as a proper size range since more grinding means more energy consumption The results would help for the improvement of bioleaching of manganese nodule as a less expensive, energy-efficient, and environment-friendly technology as compared to the existing physicochemical metal recovery technologies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.73-73
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• 2009

트렌지스터의 채널 길이가 줄어듦에 따라 절연층으로 쓰이는 $SiO_2$의 두께는 얇아져야 한다. 이에 따라 얇아진 절연층에서 터널링이 발생하여 누설전류가 증가하게 되어 소자의 오동작을 유발한다. 절연층에서의 터널링을 줄여주기 위해서는 High-K와 같은 유전율이 높은 물질을 이용하여 절연층의 두께를 높여주어야 한다. 최근에 각광 받고 있는 High-K의 대표적인 물질은 $HfO_2$, $ZrO_2$와 $Al_2O_3$등이 있다. $HfO_2$, $ZrO_2$와 $Al_2O_3$는 $SiO_2$보다 유전상 수는 높지만 밴드갭 에너지, 열역학적 안정성, 재결정 온도와 같은 특성 면에서 $SiO_2$를 완전히 대체하기는 어려운 실정이다. 최근 연구에 따르면 기존의 High-K물질에 금속을 첨가한 금속산화물의 경우 밴드갭 에너지, 열역학적 안정성, 재결정 온도의 특성이 향상되었다는 결과가 있다. 이 금속 산화물 중 $HfAlO_3$가 대표적이다. $HfAlO_3$는 유전상수 18.2, 밴드캡 에너지 6.5 eV, 재결정 온도 $900\;^{\circ}C$이고 열역학적 안전성이 개선되었다. 게이트 절연층으로 사용될 수 있는 $HfAlO_3$는 전극과 기판사이에 적층구조를 이루고 있어, 이방성 식각인 건식 식각에 대한 연구가 필요하다. 본 연구는 $BCl_3$/Ar 유도결합 플라즈마를 이용하여 $HfAlO_3$ 박막의 식각 특성을 알아보았다. RF Power 700 W, DC-bias -150 V, 공정압력 15 mTorr, 기판온도 $40\;^{\circ}C$를 기본 조건으로 하여, $BCl_3$/Ar 가스비율, RF Power, DC-bias 전압, 공정압력에 의한 식각율 조건과 마스크물질과의 선택비를 알아보았다. 플라즈마 분석은 Optical 이용하여 진행하였고, 식각 후 표면의 화학적 구조는 X-ray Photoelectron Spectroscoopy(XPS) 분석을 통하여 알아보았다.

• Journal of the Korean Chemical Society
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• v.40 no.5
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• pp.341-346
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• 1996

Electrochemical determination of iodide was carried out by stripping voltammetry with a $(Cin)Cu(NO_3)_2$ modified-carbon paste electrode. Iodide was coordinated onto the electrode surface containing $(Cin)Cu(NO_3)_2$ via ion exchange. The oxidation peak potential of incorporated iodide was ＋0.72 V. The optimum analytical conditions for the determination of iodide were investigated using linear sweep voltammetry. Optimum conditions for the electrochemical determination of iodide were as follows: i) A predeposition solution was 0.1 M $KNO_3.$ ii) The deposition time was 10 min. iii) The composition of the electrode was 40% (w/w). The detection limit for iodide was $1.0{\times}10^{-6}M$ and the relative standard deviation was ${\pm}5.5%\;in\;2.0{\times}10^{-5}M$(four repetitions). The interference effect of other anions were also investigated. $Cl^-,\;Br^-,\;C_2O_4^{2-},\;and\;ClO_4^-$ ions do not interfere for the determination of iodide. When $SCN^-$ was added to the deposition solution, the oxidation peak current of iodide ion was decreased roughly 32%.

• Korean journal of applied entomology
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• v.35 no.2
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• pp.146-152
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• 1996

The adult of the aphidophagous ladybeetle, Harmonia axyridis, was reared by feeding an artificial diet (chicken's 1iver:sugar = 5:2, v/w). The adult ladybeetle used was from pupae collected in the field in midJuly. Yolk protein production, fecundity and longevity of the adult female were checked under 3OoC, 16L:8D. Yolk proteins (Vg3 and Vg4) were detected from the hemolymph of the female 5 days after the emergence. One hundred pairs of female and male were reared separately. First oviposition started from 7 days afier the emergence and laid an average of 163.9k144.0 eggs during lifetime. Seventeen females did not lay eggs at all. Longevity of the female was 60.6k16.9 days. The application of a JH analog, methoprene (2.5 pg), caused the occurrence of yolk proteins in the hemolymph 1 day earlier than that of the control. Weekly application of 2.5 pg of methoprene induced 83.3% from the 30 females to lay eggs within 15 days after the emergence, while the control had 51% only. Methoprene made all females lay eggs, causing the increase in the fecundity. Though the longevity of the female was not effected by the weekly application of methoprene, one time excess dose (12.5 pg) caused high in mortality and low in fecundity.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.1-7
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• 2021

Using stereo, light, and scanning electron microscopes, we researched the anatomical and histological structure of Chaenogobius gulosus's olfactory organ and compared it to those of sympatric gobies Luciogobius guttatus and Favonigobius gymnauchen. Results revealed the following common characteristics: i) tubular anterior nostril (AN) and flat posterior nostril (PN), ii) a single longitudinal lamella, iii) two accessory nasal sacs (ANS, ethmoidal and lacrimal), iv) abundant sensory epithelium lymphatic cells (LC), v) an eosinophil cell, and vi) a ciliary length a quarter of the knob diameter in the olfactory receptor neuron (ORN). Some characteristics are specific to C. gulosus and different from the other two gobies: i) 0.5~1.0 mm AN and 0.2~0.5 mm PN (vs. 0.2~0.3 mm and 0.2~0.3 mm in L. guttatus; 0.2~0.4 mm and 0.1~0.3 mm in F. gymnauchen), ii) two ANS (vs. absence in L. guttatus; two in F. gymnauchen), iii) abundant LC (vs. low in L. guttatus and F. gymnauchen), iv) low density non-sensory cilia on the lamellar surface (vs. high in L. guttatus; low in F. gymnauchen), and v) a quarter ciliary length to knob diameter ratio in the ORN (vs. mixture of a quarter to equal ratio in L. guttatus; two or three times in F. gymnauchen). From these results, we confirmed the C. gulosus olfactory organ has adapted anatomically and histologically to the sand-rock tidal zone.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.62-67
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• 2009

Ti and Ti-alloys have good biocompatibility, appropriate mechanical properties and excellent corrosion resistance. However, the widely used Ti-6Al-4V is found to release toxic ions (Al and V) into the body, leading to undesirable long-term effects. Ti-6Al-4V has much higher elastic modulus (100 GPa) than cortical bone (20 GPa). Therefore, titanium alloys with low elastic modulus have been developed as biomaterials to minimize stress shielding. The electrochemical behavior of surface-modified and MC3T3-E1 cell-cultured Ti-30(Nb,Ta) alloys with low elastic modulus have been investigated using various electrochemical methods. Surfaces of test samples were treated as follows: $0.3{\mu}m$ polished; $25{\mu}m$, $50{\mu}m$ and $125{\mu}m$ sandblasted. Specimen surfaces were cultured with MC3T3-E1 cells for 2 days. Average surface roughness ($R_a$) and morphology of specimens were determined using a surface profilometer, OM, and FE-SEM. Corrosion behavior was investigated using a potentiostat(EG&G PARSTAT 2273), and electrochemical impedance spectroscopy was performed (10 mHz to 100 kHz) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The microstructures of the Ti-30(Ta,Nb) alloys had a needle-like appearance. The $R_a$ of polished Ti-30Ta and Ti-30Nb alloys was lower than that of the sandblasted Ti alloy. Cultured cells displayed round shapes. For polished alloy samples, cells were well-cultured on all surfaces compared to sandblasted alloy samples. In sandblasted and cell-cultured Ti-30(Nb,Ta) alloy, the pitting potential decreased and passive current density increased as $R_a$ increased. Anodic polarization curves of cell-cultured Ti alloys showed unstable behavior in the passive region compared to non-cell-cultured alloys. From impedance tests of sandblasted and cell-cultured alloys, the polarization resistance decreased as $R_a$ increased, whereas, $R_a$ for cell-cultured Ti alloys increased compared to non-cell-cultured Ti alloys.

• Applied Biological Chemistry
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• v.49 no.1
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• pp.55-59
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• 2006

This study was designed to investigate the optimum manufacturing condition of germanium-fortified yeast, and the binding properties of germanium (Ge) in germanium-fortified yeast. The nutritional optimum conditions were glucose 3.0 (w/v) %, yeast extracts 0.3 (w/v) % and peptone 0.5 (w/v) %, and the amounts of yeast cells were 67.4 mg/ml. And, the standard germanium-fortified yeast was produced under the condition at the ratio of yeast cell and germanium solution was 1 : 0.5 (50%), pH 6.5 and $35-40^{\circ}C$ during fermentation. In results of the identification, binding of germanium-protein showed structural difference between the inorganic Ge $(GeO_2)$ added during fermentation process and germanium-fortified yeast. Therefore, germanium-fortified yeast made by biosynthetic technology formed structurally safe organic germanium during fermentation process. Germanium-fortified yeast can be applied as a new functional material far the improvement of health, the prevention and treatment of chronic degenerative disease like cancer, and the enforcement of immune system.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.328-334
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• 1997

Pharmacokinetics of DWP401, a recombinant human epidermal growth factor (rhEGF), was studied using radioimmunoassay (RIA) and $^{125}I$-DWP401 in rats. When DWP401 was adm inistered i.v. at doses of 50 and 500 mcg/kg, the plasma DWP401 disappeared biiexponentially with terminal half life of 4.7 and 92.8 min. The $C_{max}$ and $T_{max}$ after s.c. administration of ti at doses of 50 and 500 ${\mu}g$/kg were determined to be 23.6 and 17.5 ng/ml at 50 ${\mu}g$/kg, and 261.4 ng/ml and 36.8 min, respectively. Both the total urinary and biliary recoveries of intact DWP401 2343 very low (<0.4%), probably due to its extensive degradation in the body. the concentration ratio of DWP401 between the organ and plasma decreased especially in the liver and kidney as the dose and time after the dose increased. For example, the liver/plasma and kidney/plasma concentration ratio of DWP401 at 2.5 min after i.v. doses of 50 ${\mu}g$/kg were comparable and much larger than unity. But, the ratio at 2.5 min after i.v. doses of 500${\mu}g$/kg was much larger in the kidney that in than in the liver. These results suggest that the systemic administration of DWP401 might be subject to rapid and extensive clearance from circulation within several hour after main distrbution to liver and kidney.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.9
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• pp.931-935
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• 2012

In this study, we fabricate and investigate low-temperature solid oxide fuel cells with a ceramic substrate/porous metal/ceramic/porous metal structure. To realize low-temperature operation in solid oxide fuel cells, the membrane should be fabricated to have a thickness of the order of a few hundreds nanometers to minimize IR loss. Yttrium-doped barium zirconate (BYZ), a proton conductor, was used as the electrolyte. We deposited a 350-nm-thick Pt (anode) layer on a porous substrate by sputter deposition. We also deposited a 1-${\mu}m$-thick BYZ layer on the Pt anode using pulsed laser deposition (PLD). Finally, we deposited a 200-nm-thick Pt (cathode) layer on the BYZ electrolyte by sputter deposition. The open circuit voltage (OCV) is 0.806 V, and the maximum power density is 11.9 mW/$cm^2$ at $350^{\circ}C$. Even though a fully dense electrolyte is deposited via PLD, a cross-sectional transmission electron microscopy (TEM) image reveals many voids and defects.

• Journal of the Korean Chemical Society
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• v.43 no.5
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• pp.547-551
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• 1999

The phase change upon Bi substitutions in $Ca_{1.5-1.5x}Bi_xVO_4$ has been systematically studied. The x value corresponding to the maximum Bi substitutions reades to 0.14 and in this range($x{\leq}0.14$), the single phasic $Ca_3(VO_4)_2$ can be identified. However, a new phase of $BiV_{1.025}O_{4+x}$ is apparently formed along with the $Ca_3(VO_4)_2$ phase, when the x value exceeds beyond 0.18 ($x{\geq}0.18$). As a result of Bi substitution in the range of x$\leq$0.14, the interplanar space($d_300$) becomes larger as the Bi content increases. Since the composition of single phasic $Ca_{1.29}Bi_{0.14}VO_4$ (x=O.14) is, however, incongruent melting one, no definite melting point could be observed. But we found that its solidus temperature was 1182$^{\circ}C$ by DTA analysis.