• Bulletin of the Korean Chemical Society
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• v.5 no.4
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• pp.149-153
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• 1984

Reactions of $MoOCl_5^{2-}$ with ${\alpha}_2-[P_2W_{17}O_{61}]^{10-}$ have been studied spectrophotometrically and several complexes have been identified. The transient species initially formed is probably $[Mo_2O_4(P_2W_{17}O_{6l})_2]^{18-}$. At $pH {\le} 3$the visible spectrum changes gradually, indicating formation of a transient isomer of $[P-2Mo^VW_{17}O_{62}]^{7-}$, which again transforms into the stable isomer. The transient isomer absorbs light much more strongly than the stable isomer in the visible range. At $pH > 3 [P_2W^VW_{16}O_{61}]^{11-}$ is formed probably via the transient isomer of $[P_2Mo^VW_{17}O_{61}]^{7-}$.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1150-1154
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• 2001

Silicon oxynitride (SiON) thick films using the core layer of silica optical waveguide have been deposited on Si wafer by PECVD at low temperature (32$0^{\circ}C$) were obtained by decomposition of appropriate mixture of (SiH$_4$+$N_2$O+$N_2$) gaseous mixtures under RF power and SiH$_4$/($N_2$O+$N_2$) ratio deposition condition. Prism coupler measurements show that the refractive indices of SiON layers range from 1.4663 to 1.5496. A high SiH$_4$/($N_2$O+$N_2$) of 0.33 and deposition power of 150 W leads to deposition rates of up to 8.67 ${\mu}{\textrm}{m}$/h. With decreasing SiH$_4$/($N_2$O+$N_2$) ratio, the SiON layer become smooth from 41$\AA$ to 6$\AA$.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1427-1433
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• 2019

In this paper, Gas engine was tested for the energy of synthesis gas. As excess air ratio increase 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 in 1800 rpm and synthesis gas, thermal efficiency generally decrease and power generation was 34 kWm at λ 1.4. And excess air ratio increase 1, 1.1, 1.2, 1.3, 1.4 in power generation 34 kWm, thermal efficiency generally increase 34.2%, 36.9%, 37.2%, 37.4%, 38.1%. Total efficiency through power generation consumes 38.7 kg/h of fuel at 30 kWe load and recovers 57.3% of waste heat by recovering 57.3 kW of waste heat through 32.1% power generation efficiency and heat recovery from cooling water and exhaust gas. The total efficiency was 85.8%.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.368-373
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• 1993

LCVD법에 의한 박막성장장치를 제작하였다. 제작한 CO2 레이저는 CO2 : N2 : He이 1 : 1 : 8로 혼합된 가스를 사용하였으며 최대 출력은 60W였고 혼합가스의 유량이 20l/min, 방전전류 40mAdlfEo 50W의 비교적 안정된 출력을 얻을 수 있었다. 반응실의 기초 진공은 1$\times$10-6torr였으며 레이저를 기판에 수직 혹은 수평으로 조사할 수 있도록 설계하였다. 제작된 장치로 SiH4 및 NH3를 재료로 하여 실리콘 및 quartz 기판위에 silicon nitride 박막을 증착하였다. 박막 생장시 가스를 흘리는 방식보다 가스를 채워놓고 하는 방식이 낮은 레이저 출력하에서 균일한 박막을 얻는데 효율적이라는 것을 발견하였다. 출력 55W의 레이저를 실리콘 기판에 5분간 조사하였을 때 최대 두께1.5$mu extrm{m}$의 박막을 얻었으며 quartz 기판위에는 출력 4W, 조사시간 6분에서 두께가 약 1$\mu\textrm{m}$인 비교적 균질의 박막을 얻을 수 있었다. FT-IR 및 XPS 분석 결과 SiH4와 NH3의 혼합비가 1 : 12일 때 비교적 nitride화가 잘 된 박막이 얻어졌음을 알았다.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.570-574
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• 2011

Large colorless single crystals of analcime with diameters up to 0.20 mm have been synthesized from gels with the composition of $3.00SiO_2$ : $1.50NaAlO_2$ : 8.02NaOH : $454H_2O$ : 5.00TEA. The fully $Na^+$-exchanged analcime have been prepared with aqueous 0.1 M NaCl (pH adjusted from 6 to 11 by dropwise addition of NaOH). The single-crystal structure of hydrated $|Na_{0.94}(H_2O)|[Si_{2.06}Al_{0.94}O_6]$-ANA per unit cell, a=13.703(3) ${\AA}$, has been determined by single-crystal X-ray diffraction technique in the orthorhombic space group Ibca at 294 K. The structure was refined using all intenties to the final error indices (using only the 1,446 reflections for which $F_o$ > $4{\sigma}(F_o))R_1/wR_2$ = 0.054/0.143. About 15 $Na^+$ ions are located at three nonequivalent positions and octahedrally coordinated. The chemical composition is $Na_{0.94}(H_2O)Si_{2.06}Al_{0.94}O_6$. The Si/Al ratio of synthetic analcime is 2.19 determined by the occupations of cations, 14.79, in the single-crystal determination work.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.335-343
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• 2019

In this study, $Sr_2Ni_{1.8}Mo_{0.2}O_{6-{\delta}}$ (SNM) with a double perovskite structure was investigated as an alternative anode for use in the $CH_4$ fuel in solid oxide fuel cells. SNM demonstrates a double perovskite phase over $600^{\circ}C$ and marginal crystallization at higher temperatures. The Ni nanoparticles were exsolved from the SNM anode during the fabrication process. As the SNM anode demonstrates poor electrochemical and electro-catalytic properties in the $H_2$ and $CH_4$ fuels, it was modified by applying a samarium-doped ceria (SDC) coating on its surface to improve the cell performance. As a result of this SDC modification, the cell performance improved from $39.4mW/cm^2$ to $117.7mW/cm^2$ in $H_2$ and from $15.9mW/cm^2$ to $66.6mW/cm^2$ in $CH_4$ at $850^{\circ}C$. The mixed ionic and electronic conductive property of the SDC provided electrochemical oxidation sites that are beyond the triple boundary phase sites in the SNM anode. In addition, the carbon deposition on the SDC thin layer was minimized due to the SDC's excellent oxygen ion conductivity.

• Journal of Wetlands Research
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• v.19 no.3
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• pp.303-310
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• 2017

This paper is to understand the settling properties of cohesive sediments under effects of ions in turbulent flow. The experiments were conducted using a miniature annular flume(mini flume) with a free water surface. Silica was used as sediment of experiment. The suspended concentrations were measured by using a CCD-Camera. Settling of silica($SiO_2$) was allowed to occur under various shear stresses in a concentration of 7g/L. At condition of pH 4.2 and high NaCl concentration, the floc size D of silica was larger than D at condition of pH6.8 with the bed shear stress increasing. The settling velocity $W_s$ of silica was higher at condition of 10g NaCl/L than $W_s$ at condition of pH4.2. Comparison of measured concentration-time curves and concentration-time curves calculated by this study showed similar tendency in flow under effects of ions.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.6
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• pp.565-570
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• 2002

We introduce the concepts of fuzzy H-continuity and fuzzy strongly closed graph, respectively and investigate some of their properties.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.242-256
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• 1997

The physico-chemical properties and possible biological functionalities of commercially available persimmon vinegars were studied by measuring the specific gravity, turbidity, color, pH, total acidity, reducing sugars, alcohols, total nitrogen content, composition of organic acids and amino acids, soluble pectin, soluble tannin, ascorbic acid, acetoinic compounds, electron donating ability and nitrite scavenging ability. Persimmon vinegars had low specific gravity(1.005-1.0200) and lightness(40.03-54.95), but high turbidity (0.12-1.311, absorptivity at 660 nm), redness(1.65--0.64) and yellowness(4.54-8.14) compared to the other fruit vinegars reported. These physical property values of the individiual product differed greatly. The tested persimmon vinegars contained relatively large amount of reducing sugars(0.45-0.84%, w/v), alcohol(0.16-3.18%, w/v) and total nitrogen(30-60mg%, w/v). The pH values (average 3.70) of products were relatively high and the total acidities(average 3.04%, w/v) of the tested persimmon vinegars were lower than that($TA{\geq}4.0%$) specified by the Korean standard for fruit vinegar. The major organic acids identified in the tested products were acetic acid(17.6-72.9%) and lactic acid(25.1-74.1%). The acetic acid contents in the 5 products out of the 7 tested persimmon vinegars were lower than lactic acid content. The level of free amino acids of the persimmon vinegars were relatively high in arginine, methionine and threonine. Persimmon vinegars contained relatively large amount of soluble pectin(91.8-232.8mg%, w/v), soluble tannin(49.0-161.7mg%, w/v) and ascorbic acid(12.8-29.6mg%, w/v). The persimmon vinegars were high in 2,3-butanediol (average 166.90ppm) and acetoin(average 111.43ppm). The persimmon vinegars showed strong electron donating ability and nitrite scavenging ability.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.900-903
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• 1995