• 한국재료학회지
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• 제30권11호
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• pp.636-640
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• 2020

Due to the serious air pollution problem, interest in eco-friendly vehicles is increasing. Solving the problem of pollution will necessitate the securing of high energy storage technology for batteries, the driving force of eco-friendly vehicles. The reason for the continuing interest in the transition metal oxide LiMO₂ as a cathode material with a layered structure is that lithium ions reveal high mobility in two-dimensional space. Therefore, it is important to investigate the effective intercalation and deintercalation pathways of Li⁺, which affect battery capacity, to understand the internal structure of the cathode particle and its effect on the electrochemical performance. In this study, for the cathode material, high nickel Ni_0.8Co_0.1Mn_0.1(OH)₂ precursor is synthesized by controlling the ammonia concentration. Thereafter, the shape of the primary particles of the precursor is investigated through SEM analysis; X-ray diffraction analysis is also performed. The electrochemical properties of LiNi_0.8Co_0.1Mn_0.1O₂ are evaluated after heat treatment.

• Archives of Pharmacal Research
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• 제19권3호
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• pp.173-177
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• 1996

The Pneumococcus, Streptococcus pneumoniae, has an ample polysaccharide (PS) capsule that is highly antigenic and is the main virulence factor of the organism. The capsular PS is the source of PS vaccine. This investigation was undertaken to optimize the culture conditions for the production of capsular PS by type 4 pneumococcus. Among several culture media, brain heart infusion (BHI) and Casitone based medium were found to support luxuriant growth of pneumococcus type 4 at the same level. Therefore in this study, the Casitone based medium was used to study optimization of the culture condition because of BHI broth's high cost and complex nature. The phase of growth which accomodated maximum PS production was exponential phase. Concentrations of glucose greater than 0.8% did not enhance growth or PS production. Substitution of nitrogen sources with other resources or supplementation of various concentrations of metal ion (with the exception of calcium, copper, and magnesium ions) had adverse effects on growth and PS production. On the other hand, low level aeration and supplementation of 3 mg/l concentration of asparagine, phenylalanine, or threonine were beneficial for increased PS production. The synergistic effect of all the favorable conditions observed in pneumococcal growth assays provided a two-fold cumulative increase in capsular PS production.

• Food Science and Biotechnology
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• 제18권3호
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• pp.682-688
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• 2009

Changes in lipophillic pigments concentration and its relation to color of fresh green tea liquor during heat treatment were studied. The results showed liquor greenness decreased markedly with extension of incubation time at $55^{\circ}C$, while the brightness and yellowness changed a little. Significant increase in 'a' and 'b' values of tea liquor was observed at $95^{\circ}C$. Color change of liquor at $55^{\circ}C$ was accompanied by a decrease in the level of chlorophylls, lutein and neoxanthin, and an increase in the pheophytins and ${\beta}-carotene$ levels. However, all pigments except ${\beta}-carotene$ decreased with time extension at $95^{\circ}C$. Significant correlation was found between pigments and color difference index. The browning of fresh green tea liquor was attributed to vicissitudes of lipophillic pigments during heat treatment, especially to the change of chlorophylls/pheophytins ratio. Result also showed addition of $Zn^{2+}$ at 1.6 ${\mu}mol/L$ could partially alleviate the decrease in greenness during heat treatment.

• 한국세라믹학회지
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• 제35권10호
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• pp.1007-1013
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• 1998

The samples of Bi2Sr2Ca1-xNaxCu2O8+y with various carrier concentration were synthesized by substituting Na for Ca ion. The superconducting properties hall coefficients and X-ray powder diffraction were measur-ed the sampled. Single phase samples were obtained for 0$\leq$x<0.3 of Bi2Sr2Ca1-xNaxCu2O8+y In the single phase the critical temperature. {{{{ { T}_{c } }} and carrier concentration increase with the increase of Na concentration pass through a maximum and then decreases. In the range of x$\geq$0.7 to the Na doped samples however we observed the metal-semiconductor transition. The c-axis seemed to decrease and a and b-axes increase with increasing Na concentration in the single phase. Decreasing of c-axis while increasing x is due to the smaller size of {{{{ {Na}^{+1 } }} ions to the {{{{ { Ca}^{+2 } }} ions. In the range of x>0.3 however the trend becomes ambiguous due to the inclusion of the 10K phase and impurity phase.

• 분석과학
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• 제17권1호
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• pp.23-28
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• 2004

Trace amount of uranyl (II) has been determined spectrophotometrically by measuring the optical density of the light blue yellowish coloured solutions formed by reaction between the metal ion and nicotinohydroxamic acid (NHx) in presence of different secondary ligands in strong isoamyl alcohol alkaline medium. The absorption maxima for both aqueous and extracted systems measured at their respective optimum pH were found to be 360 and 559 nm (DETA), 375 and 358 nm (EDA), 369 and 362 nm (piperidine), 354 and 341 nm (pyridine) and 363 and 336 nm (3 piperidine), 354 and 341 nm (pyridine) and 363 and 336 nm (3 - picoline), respectively at which Beer's law was obeyed. Effect of pH, reagent concentration, order of addition of reagent, time, temperature and solvent media on the absorption spectra have also been studied. Among the different systems studied, the shortest concentration range of uranyl(II) adhering to Beer's Law was 2.4 - 10.5 ppm observed for $UO_2(II)$ - NHx - DETA system in aqueous medium and also for iso amyl alcohol(IAA) extracted $UO_2$ - NHx - pyridine system was 2.4 - 7.8.

• 조명전기설비학회논문지
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• 제29권11호
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• pp.28-34
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• 2015

By incorporating a 966nm near infrared laser, we demonstrated bidirectional current triggering of between 0 and 10mA in a two-terminal planar device based on a highly resistive vanadium dioxide ($VO_2$) thin film grown by a pulsed laser deposition method. A two-terminal planar device, which had an electrode separation of $100{\mu}m$ and a $50{\mu}m-wide$ $VO_2$ conducting layer, was fabricated through ion beam-assisted milling and photolithographic techniques. A bias voltage range for stable bidirectional current triggering was determined by investigating the current-voltage curves of the $VO_2-based$ device in a current-controlled mode. Bidirectional current triggering of up to 10mA was realized by directly illuminating the $VO_2$ film with a focused infrared laser beam, and the transient responses of triggered currents were analyzed when the laser was modulated at various pulse widths and repetition rates. A switching contrast between off- and on-state currents was evaluated as ~3571, and the rising and falling times were measured as ~40 and ~20ms, respectively.

• Preventive Nutrition and Food Science
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• 제17권2호
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• pp.116-121
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• 2012

Water extract from Pinus densiflora (WPD) was investigated for its antioxidant activity and its ability to provide protection from DNA damage. A series of antioxidant assays, including a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay, a reducing power assay, a metal-chelating assay, a superoxide radical scavenging assay, and a nitrite scavenging ability, as well as a DNA damage protection assay were performed. Total phenolic content was found to be 211.32 mg Tan/g WPD. The extract scavenged 50% DPPH free radical at a concentration of 21.35 ${\mu}g/mL$. At that same concentration, the reducing power ability of WPD was higher than that of ${\alpha}$-tocopherol. The extract chelated 68.9% ferrous ion at the concentration of 4 mg/mL. WPD showed better nitrite scavenging effect at the lower pH. Meanwhile, WPD exhibited a strong capability for DNA damage protection at 1 mg/mL concentration. Taken together, these data suggest water extract from Pinus densiflora could be used as a suitable natural antioxidant.

• Transactions on Electrical and Electronic Materials
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• 제6권2호
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• pp.46-50
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• 2005

BST thin films were etched with inductively coupled CF$_{4}$/(Cl$_{2}$+Ar) plasmas. The etch characteristics of BST thin films as a function of CF$_{4}$/(Cl$_{2}$+Ar) gas mixtures were analyzed using optical emission spectroscopy (OES) and Langmuir probe. The BST films in CF$_{4}$/Cl$_{2}$/Ar plasma is mainly etched by the formation of metal chlorides which depends on the emission intensity of the atomic Cl and the bombarding ion energy. The maximum etch rate of the BST thin films was 53.6 nm/min because small addition of CF$_{4}$ to the Cl$_{2}$/Ar mixture increased chemical and physical effect. A more fast etch rate of BST films can be obtained by increasing the DC bias and the RF power, and lowering the working pressure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.454-454
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• 2010

In order to achieve a high efficient a-Si solar cell, the TCO (transparent conductive oxide) substrates are required to be a low sheet resistivity, a high transparency, and a textured surface with light trapping effect. Recently, a zinc oxide (ZnO) thin film attracts our attention as new coating material having a good transparent and conductive for TCO of solar cells. In this paper the optical properties of $H_2$ post-treated BZO (boron doped ZnO, ZnO:B) thin film are investigated with $O_2$-plasma treatment. The BZO thin films by MOCVD (Metal Organic Chemical Vapor Deposition) are investigated and the samples of $H_2$ post-treated BZO thin film are tested with $O_2$-plasma treatment by plasma treatment system with 13.56 MHz as RIE (Reactive Ion Etching) type. We measured the optical properties and surface morphology of BZO thin film with and without $O_2$-plasma treatment. The optical properties such as transmittance, reflectance and haze are measured with integrating sphere and ellipsometer. This result of the BZO thin film with and without $O_2$-plasma treatment is application to the TCO for solar cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.90.2-90.2
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• 2013

Vertically-aligned silicon nanostructure arrays (SNAs) have been drawing much attention due to their useful electrical properties, large surface area, and quantum confinement effect. SNAs are typically fabricated by chemical vapor deposition, reactive ion etching, or wet chemical etching. Recently, metal-assisted chemical etching process, which is relatively simple and cost-effective, in combination with nanosphere lithography was recently demonstrated for vertical SNA fabrication with controlled SNA diameters, lengths, and densities. However, this method exhibits limitations in terms of large-area preparation of unperiodic nanostructures and SNA geometry tuning independent of inter-structure separation. In this work, we introduced the layerby- layer deposition of polyelectrolytes for holding uniformly dispersed polystyrene beads as mask and demonstrated the fabrication of well-dispersed vertical SNAs with controlled geometric parameters on large substrates. Additionally, we present a new means of building in vitro neuronal networks using vertical nanowire arrays. Primary culture of rat hippocampal neurons were deposited on the bare and conducting polymer-coated SNAs and maintained for several weeks while their viability remains for several weeks. Combined with the recently-developed transfection method via nanowire internalization, the patterned vertical nanostructures will contribute to understanding how synaptic connectivity and site-specific perturbation will affect global neuronal network function in an extant in vitro neuronal circuit.