• 한국표면공학회지
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• 제10권3호
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• pp.3-11
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• 1977

3가크롬 鍍金法은 6가크롬 鍍金法의 諸 欠点을 克服할 수 있다는 事실이 알려져 外國에서는 오래 前 부터 工業的 실用化를 위한 硏究가 活潑하게 行하여 졌고, 이중 최근에 發表된 Alecra 3 process는 電着諸特性이 뛰어난 方法으로 裝飾크롬 鍍金 分野에 利用되고 있다고 한다. 本 硏究는 Alecra 3 process의 浴 組成中 개미산칼륨으로, 염화칼륨을 염화나트륨으로 大替한 浴의 電着諸特性을 調査하고 最適 염化크롬의 濃度와 錯化比를 함께 調査하여 다음과 간은 結果를 얻었다. (1) 外觀, 被覆性,均一電着性 및 平均 電析 速度 등은 염화크롬 濃度가 0.4 mol일때 가장 良好하였다. (2) 개미산나트륨 대 염화크롬의 mol比는 염화크롬이 0.4 mol일때 2~3이 比較的 良好한 電着諸特性을 보여 주었다. (3) 개미산나트륨 및 염화나트륨 含有한 鍍金浴의 電着諸特性은 Alecra 3 Process의 特性과 비슷하였다.

• 한국세라믹학회지
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• 제47권3호
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• pp.249-255
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• 2010

To investigate optical properties of (V, Pr)-doped $ZrSiO_4$ green pigments, samples were prepared by the ceramic method using NaF and NaCl as mineralizers. They were characterized by X-ray diffraction, UV-Vis spectroscopy and Raman spectroscopy. The changes of color in the samples during heating and effect of mineralizers were studied in terms of valence of the vanadium and praseodymium in the zircon matrix. (V, Pr)-doped $ZrSiO_4$ pigments give rise to green coloration in $800^{\circ}C$. The oxidation state of V and Pr ions of pigments in the glazed samples were confirmed by UV-Vis absorption spectra. This absorption spectra showed three typical bands of trivalent Pr at the 445, 480~490, 592 nm due to f-f transitions and two broad bands of 302~380, 400~500 nm due to f-d transitions of tetravalent Pr. According to the increasing amounts of $Pr_6O_{11}$, the two broad bands showed decreasing intensity at 290, 640 nm due to d-d transitions of tetravalent V.

• 한국토양비료학회지
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• 제43권5호
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• pp.734-740
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• 2010

Overuse of veterinary antibiotics threats public health and surrounding environment due to the occurrence of antibiotic resistant bacteria. The objective of this study was to evaluate the antibiotic's concentrations of tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC) in a tetracycline group (TCs), sulfamethazine (SMT), sulfamethoxazole (SMX), and sulfathiazole (STZ) in a sulfonamide group, lasalocid (LSL), monensin (MNS), and salinomycin (SLM) in a ionophore (IPs), and tylosin (TYL) in a macrolide (MLs) group from soil, water, and sediment samples adjacent to a cattle manure composting facility. For all samples of soil, water, and sediment, the highest concentrations were detected in TCs among the tested antibiotics because of its higher annual consumption in veterinary farms, Korea and its higher cohesiveness with divalent or trivalent cations in soil. Moreover, the concentrations of residual antibiotics in September were generally higher than in June because of heavier rainfall in June. We suggest that continual monitoring and developing guideline of antibiotics are needed to control residual antibiotics in the environment.

• 한국광물학회지
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• 제16권3호
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• pp.245-254
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• 2003

본 연구에서는 10∼15 ㎬의 압력, $1000∼1400 ^{\circ}C$의 온도 조건에서 함수 현무암질 물질로부터 합성된 스티쇼바이트의 함수량을 결정하였고, 스티쇼바이트에 고용하는 알루미늄과 수소와의 치환 메커니즘을 고찰하였다. 단결정 스티쇼바이트의 최대 함수량은 $844\pm$44 ppm $H_2$O이며, 수소 고용은 3가이온(주로 알루미늄)에 비례하여 증가하며, 다른 원소들보다 온도에 민감하다. 이러한 결과는 무수광물 중에서 스티쇼바이트는 중요한 함수상임을 시사하며, 하부맨틀로 물을 수송하는 중요한 운반매체 역할을 한다고 판단된다.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.117-121
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• 2018

Perovskite solar cells have received increasing attention in recent years because of their outstanding power conversion efficiency (exceeding 22%). However, they typically contain toxic Pb, which is a limiting factor for industrialization. We focused on preparing Pb-free perovskite films of Ag-Bi-I trivalent compounds. Perovskite thin films with improved optical properties were obtained by applying an anti-solvent (toluene) washing technique during the spin coating of perovskites. In addition, the surface condition of the perovskite film was optimized using a multi-step thermal annealing treatment. Using the optimized process parameters, $AgBi_2I_7$ perovskite films with good absorption and improved planar surface topography (root mean square roughness decreased from 80 to 26 nm) were obtained. This study is expected to open up new possibilities for the development of high performance $AgBi_2I_7$ perovskite solar cells for applications in Pb-free energy conversion devices.

• Environmental Engineering Research
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• 제22권1호
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• pp.61-74
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• 2017

This study investigated the effect of various cations ($Ca^{2+}$, $Mg^{2+}$, $Al^{3+}$, $Mn^{2+}$, $Zn^{2+}$) on the autoaggregation (AAg) and surface hydrophobicity (SHb) of three different bacteria (Brevibacillus panacihumi strain (ZB1), Lysinibacillus fusiformis strain (ZB2) and Enterococcus faecalis strain (ZL)) using a 2-level factorial design. The AAg ratio was measured from the changes in the absorbance of the media. Results show that ZB2 had maximum AAg for the three bacteria investigated. A microscopic clustering of cells was observed when $Ca^{2+}$ was added to ZB2. The AAg was in the range of 62%, 58% and 34% for ZB2, ZB1 and ZL, respectively and correlated to the SHb. The aggregation and SHb of the microbial cells increased with increasing ionic strength due to the repulsive steric or overlap forces between the polymer covered surfaces. $Ca^{2+}$ demonstrated a more significant effect on aggregation and SHb of microbial cells due to an attractive binding force.

• 한국세라믹학회지
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• 제32권10호
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• pp.1178-1188
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• 1995

Bi4Ti3O12 (BIT) and its rare earth (Y, Nd, Sm, Gd)-substituted derivatives were synthesized using a sol-gel method to investigate their microstructures, cystal structures and electrical properties depending on the subsituted elemetns. Nd- or Sm-substitution into BIT appeared to be favorable, while Y- or Gd-substitution occurred with a pyrochlore phase. This suggests that a smaller trivalent rare earth ion may not be favorable in the structure of BIT. The rare earth derivatives showed that their particle sizes and shapes were considerably different depending on the kinds of substituted elements. Y-substitution resulted in developing a relatively even particle size and a dense microstructure. In structure, they may be similar to the pseudo-orthorhombic BIT but close to a paraelectric tetragonal phase. Their a (or b) axes were shortened, compared to the one of BIT. Such a distortion may result a decrease in the tilting of TiO6. BIT and the derivatives showed that their dielectric constants and losses were 40~120 and less than 0.03, respectively in the frequency range of 1~10 MHz. The dielectric loss of Y-substituted derivative was the lowest one and changed a little to frequency. Curie points were observed in all the derivatives like BIT to suggest that they would be ferroelectric. The temperature stability of the delectric properties of the derivatives below the Curie points were relatively better than the one of BIT.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.155-159
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• 2003

The preparation and luminescence characterization of yttrium oxide doped with trivalent europium phosphors by sol-gel method have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation one of appled various chelating agents. we noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for 1hrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence characterization of resultant $Y_{2}O_{3}:Eu^{3+}$ phosphor was enhanced upto maximum 30% significantly than conventional method through increasing porous region and decreasing particle sizes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.151-154
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• 2003

The synthesis and luminescent properties of trivalent europium activated gadolinium oxide red phosphors by sol-gel process have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation as chelating agents. We noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for lhrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated at about $100^{\circ}C$ was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence properties of resultant $Gd_{2}O_{3}:Eu^{3+}$ phosphor was measured by SEM, FT-IT and brightness intensity was shown 20% higher than those prepared by conventional method and by other chelating agent.

• 한국식품영양과학회지
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• 제26권3호
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• pp.475-479
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• 1997

A decrease in the circulating levels of estrogen, occuring as a consequence of post menopausal decline or from surgical ovariectomy, results in an accelerated loss of bone. Estrogen has been shown to stimulate lysyl oxidase activity, and the treatment with estrogen increased the pyridinium content of cortical bone. a trivalent mature cross-links collagen fibrils named pyridinoline, which is especially abundant in collagen of cartilage and bone, markedly increases with growth in humans and rats. The main aim of this study was to examine the increased bone loss caused by ovariectomy through monitoring the concentrations of the collagen and the pyridinium cross-links of collagen, pyridinoline. The ovariectomized rats, 4 weeks old, were divided at random into two or three groups of 5. Ovariectomies were carried out on both of the saline-treated group(OVX(NH)) and the estrogen-treated group(OVX(H)) using the dorsal approach and sham operations were performed on the sham-operated group(sham). They were maintained under identical conditions for 4 or 8 weeks and were allowed free access to food and water. it was observed that there was no significant difference between the control group and the sham-operated group, however, the control group had a higher content of collagen than the saline-treated group after 4 weeks and 8 weeks. Based on these results, iot is supposed that estrogen can enhance collagen synthesis and affects the pyridinoline formation in collagen fibrils through stimulating lysyl oxidase activity.