• 한국산학기술학회논문지
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• 제14권2호
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• pp.846-849
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• 2013

$TiO_2$ 박막을 저온 열처리 졸-겔 법으로 합성하였다. 박막의 기판은 면적이 $100mm^2$인 붕규산염 유리를 사용하여 시료를 $300^{\circ}C$부터 $1100^{\circ}C$까지 열처리하였고, 이때 제조된 박막의 두께는 약 $1.5{\mu}m$정도였다. $300^{\circ}C$에서 2시간 동안 열처리한 $TiO_2$ 박막은 아나타제 상을 나타내었고 열처리 온도가 증가함에 따라 비정질 상태에서 아나타제상과 루타일 상이 공존하면서 각 상의 분율이 변화하였다. SEM 분석에 의하면 박막의 입자 크기는 $0.1{\sim}0.54{\mu}m$이었으며 Uv-visible 반사특성에 있어서 390nm부근에서 광흡수가 되는 것을 알 수 있었다. 따라서 낮은 열처리 온도에서 생성된 $TiO_2$ 박막은 주로 아나타제 상을 가지며 광촉매 특성을 2.4배 증가시키는 것으로 나타났다.

• Korean Chemical Engineering Research
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• 제58권3호
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• pp.486-492
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• 2020

가시광 LED 빛에 반응하는 페로브스이트형 bismuth ferrite (BFO) 광촉매 제조방법과 가시광 광촉매 반응 특성을 조사하였다. BFO는 졸-겔법에 따라 제조하였다. 제조된 BFO는 주로 BiFeO₃ 구조로 이루어져 있으며 Bi₂₄Fe₂O₃₉ 구조도 포함한 나노 크기의 결정을 이루고 있었다. BFO 나노 결정은 약 600 nm까지 자외선과 가시광선을 흡수하는 것을 UV-visible 확산 반사 스펙트럼으로부터 확인하였다. 확산 반사 스펙트럼으로부터 구한 BFO의 밴드갭은 약 2.2 eV로 나타났다. 포름알데히드는 585 nm와 613 nm 파장의 가시광 LED 램프의 빛과 BFO 광촉매와의 광반응에 의하여 분해되어 제거되었다. BFO의 가시광 LED 빛에서 광촉매 활성은 BFO의 좁은 밴드갭에서 기인하는 것으로 보인다.

• 한국재료학회지
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• 제14권10호
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• pp.701-706
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• 2004

Bismuth layered structure ferroelectric thin films, La-substituted $Bi_{4}Ti_{3}O_{12}$ ($Bi_{1-x}La_{x}Ti_{3}O_{12}$, x=0.75, BLT) were prepared on the $Pt(111)/Ti/SiO_2/Si(100)$ substrates by a sol-gel spin coating process. The thin films were annealed in various conditions, i.e., oxygen, nitrogen and vacuum atmospheres for various annealing time. We investigated the annealing condition effects on the grain orientation and ferroelectric properties. The measured XRD patterns revealed that the BLT thin films showed only $Bi_{4}Ti_{3}O_{12}$-type phase with random orientation. $La^{3+}$ ion substitution for $Bi^{3+}$ ion in perovskite layers of $Bi_{4}Ti_{3}O_{12}$ decreased the degree of c-axis orientation and increased the remanent polarization ($2P_{r}$). The remanent polarization ($2P_{r}$) and the coercive field ($2E_{c}$) of the BLT thin film annealed at $650^{\circ}C$ for 5 min in oxygen atmosphere were $87{\mu}C/cm^2$ and 182 kV/cm, respectively, at an applied electric field of 240 kV/cm. For all of the BLT thin films annealed in various conditions, the fatigue resistance was shown. The improvement of ferroelectric properties with La substitution in $Bi_{4}Ti_{3}O_{12}$ could be attributed to the changes in space charge densities and grain orientation in the thin film.

• 한국재료학회지
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• 제15권8호
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• pp.508-513
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• 2005

[ $TiO_2-Fe_2O_3$ ] nanocomposite powders for magnetic photocatalyst were synthesized by sol-gel process, in which $TiO_2$ photocatalytic layer was formed on the surface of $\gamma-Fe_2O_3$ magnetic core. Transmission electron microscopy (TEM) observation and X-ray diffractometry (XRD) analysis revealed that$\gamma-Fe_2O_3$ nanoparticles, $10\~20nm$ in diameter, were coated by $TiO_2$ shell of 5nm in thickness and $TiO_2$ was anatase phase. Also hydroxyl group (-OH) used to decompose organic compounds was detected by Fourier transformation infrared spectrometry(FT-IR) analysis. UV-Visible spectrophotometry results showed that light absorption occurred in the wavelength range of $400\~700 nm$, and the band gap energy $(E_g)$ of powder was 1.8 eV. Finally it was found that the coercivity $(H({ci})$ and saturation magnetization $(M_s)$ of the powder were 79 Oe and 14.8 emu/g, respectively as experimental vibrating sample magnetometer (VSM) measurements.

• 한국세라믹학회지
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• 제45권5호
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• pp.303-308
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• 2008

Mullite precursors were synthesized with aluminosilicate gels from mixture of aluminum nitrate and sodium orthosilicate by the geopolymer technique at ambient temperature. Then, the gel was heat-treated in air up to $1200^{\circ}C$ at intervals of $100^{\circ}C$. Raw and heat-treated gels were characterized by TG-DTA, XRD, FTIR, $^{29}Si$ MAS-NMR, TEM. The result to examine the crystallization of behavior though DTA, the synthesized precursors were crystallized in the temperature range from $950^{\circ}C$ to $1050^{\circ}C$. The XRD results showed that the gel compositions were begun to crystallize at various temperature. Also, it was found that the precursors of M-4 begun to crystallize at about $950^{\circ}C$. The M-4 XRD peaks were characterized better than $M-1{\sim}M-3$ at $1000^{\circ}C$. The formation temperature of mullite in this study is much lower than that of previous sol-gel methods, which crystallized at up of $1200^{\circ}C$. TEM investigations revealed that the sample with 10 nm particle size was obtained via heat-treated at $1000^{\circ}C$ for M-4.

• Journal of Animal Science and Technology
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• 제63권2호
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• pp.461-464
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• 2021

Escherichia coli normally colonizes the lower intestine of animals and humans, but some serotypes are foodborne pathogens. The Escherichia coli K_EC180 was isolated from swine feces that were collected from a weaner pig. In this genome announcement, E. coli K_EC180 was sequenced using PacBio RS II and Illumina NextSeq 500 platforms. The complete chromosome of E. coli K_EC180 is composed of one circular chromosome (5,017,281 bp) with 50.4% of guanine + cytosine (G + C) content, 4,935 of coding sequence (CDS), 88 of tRNA, and 22 of rRNA genes. The complete genome of E. coli K_EC180 contains the toxin genes such as shiga-like toxins (stxA and stxB).

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2003년도 제3회 발생공학 국제심포지움 및 학술대회
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• pp.106-106
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• 2003

• Journal of Magnetics
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• 제16권2호
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• pp.186-191
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• 2011

[ $YBa_2C_3O_{7-x}$ ]films were fabricated on a $SrTiO_3$ (100) substrate using a trimethylaceate propionic acid (TMAP)-based MOD process by controlling the precursor solution viscosity, firing temperature, and by using various coatings. The viscosity of the precursor solution was controlled by the addition of Xylenes. The films were heat treated with different temperatures from 750 to $800^{\circ}C$. c-axis oriented films were obtained. After adding 9 ml of Xylene into the precursor solution, the $T_c$ of the YBCO film, which was coated 2 times and heat treated at $800^{\circ}C$, was 86 K and the measured $J_c$ was above 2.5 MA/$cm^2$ at 77 K in a zero-field.

• 한국환경과학회지
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• 제22권11호
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• pp.1473-1479
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• 2013

Entropy is a measure of disorder or uncertainty. This terminology is qualitatively used in the understanding of its correlation to pollution in the environmental area. In this research, three different entropies were defined and characterized in order to quantify the qualitative entropy previously used in the environmental science. We are dealing with newly defined distinct entropies $E_1$, $E_2$, and $E_3$ originated from Shannon entropy in the information theory, reflecting concentration of three major green house gases $CO_2$, $N_2O$ and $CH_4$ represented as the probability variables. First, $E_1$ is to evaluate the total amount of entropy from concentration difference of each green house gas with respect to three periods, due to industrial revolution, post-industrial revolution, and information revolution, respectively. Next, $E_2$ is to evaluate the entropy reflecting the increasing of the logarithm base along with the accumulated time unit. Lastly, $E_3$ is to evaluate the entropy with a fixed logarithm base by 2 depending on the time. Analytical results are as follows. $E_1$ shows the degree of prediction reliability with respect to variation of green house gases. As $E_1$ increased, the concentration variation becomes stabilized, so that it follows from linear correlation. $E_2$ is a valid indicator for the mutual comparison of those green house gases. Although $E_3$ locally varies within specific periods, it eventually follows a logarithmic curve like a similar pattern observed in thermodynamic entropy.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.45-45
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• 2003

Human papillomavirus type 16(HPV16) has been known to the major factor for the development of uterine cervical carcinomas. We have extended these studies to investigate the in vivo activities of HPV-16 E6/E7 when expressed in squamous epithelia of transgenic mice. Grossly, hK14HPV16E6/E7 transgenic mice had multiple phenotypes, including wrinkled skin that was apparent prior to the appearance of hair on neonates, thickened ears, and loss of hair in adults. In the transgenic mice, the wrinkled skin phenotype on the body and legs died at the age of 3∼4 weeks. Histological analysis of demonstrated that E6/E7 causes epidermal hyperplasia in multiple transgenic lineages with high penetrance. This epithelial hyperplasia was characterized by an expansion of the proliferating compartment and an expansion of the keratinocyte and was associated with hyperkeratosis. These transgenic mice expressed E6/E7 transgene mainly in skin, heart, pancreas and kidney. Hyperplasia was found at the skin. The enzyme activities of GR, GPx and CuZnSOD were measured from the transgene cause keratinocyte at the skin. The specific enzyme activities were significantly higher in transgenic mice skin compared to the normal mice skin. Thus these transgenic mice may be useful for the develpment of antioxidant enzymes or other therapies for HPV-associated hyperkeratosis.