• 한국재료학회지
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• 제21권2호
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• pp.111-114
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• 2011

As a growth-template of ZnO nanorods (NR), a hexagonal $\beta-Ni(OH)_2$ nanosheet (NS) was synthesized with the low temperature hydrothermal process and its microstructure was investigated using a high resolution scanning electron microscope and transmission electron microscope. Zinc nitrate hexahydrate was hydrolyzed by hexamethylenetetramine with the same mole ratio and various temperatures, growth times and total concentrations. The optimum hydrothermal processing condition for the best crystallinity of hexagonal $\beta-Ni(OH)_2$ NS was determined to be with 3.5 mM at $95^{\circ}C$ for 2 h. The prepared $Ni(OH)_2$ NSs were two dimensionally arrayed on a substrate using an air-water interface tapping method, and the quality of the array was evaluated using an X-ray diffractometer. Because of the similarity of the lattice parameter of the (0001) plane between ZnO (wurzite a = 0.325 nm, c = 0.521 nm) and hexagonal $\beta-Ni(OH)_2$ (brucite a = 0.313 nm, c = 0.461 nm) on the synthesized hexagonal $\beta-Ni(OH)_2$ NS, ZnO NRs were successfully grown without seeds. At 35 mM of divalent Zn ion, the entire hexagonal $\beta-Ni(OH)_2$ NSs were covered with ZnO NRs, and this result implies the possibility that ZnO NR can be grown epitaxially on hexagonal $\beta-Ni(OH)_2$ NS by a soluble process. After the thermal annealing process, $\beta-Ni(OH)_2$ changed into NiO, which has the property of a p-type semiconductor, and then ZnO and NiO formed a p-n junction for a large area light emitting diode.

• Elastomers and Composites
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• 제41권1호
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• pp.49-56
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• 2006

Allylamine을 이용하여 UV하에서 폐타이어 분말을 개질하였으며, 이를 이용한 PP/폐타이어분말 복합체의 열적, 유변학적 성질을 분석하였다. X-ray 분석결과 무수말레 산이 그라프트된 폴리프로필렌과 같은 상용화제가 없는 경우 ${\beta}$ 결정의 피크 강도가 증가한 반면 상용화제가 있는 경우 완전히 없어짐을 알 수 있었으며, DSC 결과에서도 이를 확인할 수 있었다. 개질된 폐타이어 분말을 함유한 복합체의 용융점도와 탄성모듈러스는 개질되지 않은 분말을 함유한 복합체 보다 높은 값을 나타내었으며, 이는 개질된 분말 표면의 아민기와 말레이산이 그라프트된 PP의 상호작용에 기인하는 것으로 판단된다.

• 한국진공학회지
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• 제9권4호
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• pp.321-327
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• 2000

LPCVD 방식에 의해 산화막과의 접착성이 양호하고 ~10 $\mu$\Omega$$.cm의 낮은 비저항을 갖는 텅스텐 박막을 성장시킬 수 있었다. 텅스텐의 산화막에 대한 접착성은 기판온도가 높을수록, $SiH_{4}/WF_{6}$ 비율이 증가할수록 우수하였다. 특히, 가스 비율이 2인 경우 $350^{\circ}C$에서도 텅스텐의 성장이 가능하였으며, $\beta$-W의 성장으로 비저항이 높았으나 $H_2$ carrier 가스를 증가시켜 최소화시킬 수 있었다. 따라서, 텅스텐의 산화막에 대한 접착성 향상을 위해 복잡한 증착 공정이나 부가적인 공정을 사용하지 않고 단순히 증착온도, 가스 비율, carrier 가스 조건을 조절함에 의해 해결될 수 있음을 확인하였다.

• Biomolecules & Therapeutics
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• 제24권6호
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• pp.610-615
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• 2016

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-${\beta}$-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.

• 전기학회논문지P
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• 제57권2호
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• pp.140-145
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• 2008

The purpose of this paper is to discuss the fabrication of $\beta$-PVDF($\beta$-Polyvinylidene fluoride, ${\beta}-PVF_2$) organic thin films using the vapor deposition method. Vapor deposition was performed under the following conditions: the temperature of evaporator, the applied electric field, and the pressure of reaction chamber were $270^{\circ}C$, 142.4 kV/cm, and $2.0{\times}10^{-5}\;Torr$, respectively. The molecular structure of the evaporated organic thin films were evaluated by a FT-IR. The results showed that the characteristic absorption peaks of $\beta$-form crystal increase from 72% to 95.5% with an increase in the substrate temperature. In the analysis of the electric characteristics, the abnormal increases in the relative dielectric constant and the dielectric loss factor in the regions of low frequency and high temperature are known to be caused by inclusion of impurity carriers in the PVDF organic thin films. In order to analyze quantitatively the abnormalities in the conductivity mechanism caused by ionic impurities, the product of the ion density and the mobility that affect the electrical property in polymeric insulators is analyzed. In the case of a specimen produced by varying the substrate temperature from $30^{\circ}C$ to $105^{\circ}C$, the product of mobility and the ion density decreased from $4.626{\times}10^8$ to $8.47{\times}10^7/V{\cdot}cm{\cdot}s$. This result suggests that the higher the substrate temperature is maintained, the better excluded the impurities are, and the more electrically stable material can be obtained.

• 분석과학
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• 제30권5호
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• pp.226-233
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• 2017

In general, quantitative chemical analysis in various areas including food, the environment, in vitro diagnostics, etc., requires traceability in order to increase the reliability of the measurements. Measurement traceability is a property of an unbroken chain of comparisons relating an instrument's measurements to SI units. Purity analysis is the first process for establishing traceability to SI units in chemical measurements. The purpose of this study is to develop and validate a method of purity assignment for establishing the traceability of $17{\beta}$-estradiol measurements in an in vitro diagnostics field. The establishment of this method is very important as it can be applied to the development of CRM and to the analysis of the purity of other hormones. The method of assignment of the purity of $17{\beta}$-estradiol was developed using the mass balance method and was validated through participation in an International comparison. In the mass balance method, impurities are categorized into four classes as follows: total related structure impurities, water, residual organic solvents, and nonvolatiles/inorganics. In this study, total related structure impurities were characterized by a gas chromatography-flame ionization detector (GC-FID) and a high-performance liquid chromatography-ultraviolet (HPLC-UV) detector, water content was determined by a Karl-Fisher coulometer, and total residual solvents and nonvolatiles/inorganics were checked simultaneously by thermogravimetric analysis (TGA). The purity of the $17{\beta}$-estradiol was 985.6 mg/g and the expanded uncertainty was 2.1 mg/g at 95% confidence. The developed method can be applied to the development of certified reference materials, which play a critical role in traceability.

• 한국식품과학회지
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• 제20권5호
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• pp.683-690
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• 1988

시중에서 판매되는 캔상태와 냉동상태의 당근쥬스와 신선하게 제조된 쥬스의 대한 관능적 평가 및 물리적 성질과 카로텐 함량을 연구하였다. 물리적 성질로서 점성과 산도를 측정하였고, HPLC와 spectrophotometry에 의해 알파와 베타 카로텐 및 총 카로테노이드 함량이 관찰되었다. 관능평가 결과, 캔쥬스는 냉동이나 신선한 시료에 비해 낮은 수응력을 보였으며, 특히 향기와 질감에서 낮은 적응성을 나타내었다. 또한 다른 시료에 비해 10배의 높은 점성과 낮은 산도를 나타내었다. 두 종류의 냉동시료중 한 시료는 신선한 상태의 쥬스와 모든 측정에서 같은 결과를 나타내었고, 다른 한 시료는 알파카로텐 함량이 유의적으로 낮았으나 캔보다는 2배의 함량이었다. 캔쥬스는 총 카로테노이드와 베타 카로텐 함량에서 신선한 상태나 냉동상태의 70-77%를 나타내었고, 특히 알파카로텐은 신선한 경우의 24%를 함유하였다. 관능적 평가와 물리적 성질 및 카로텐 함량면에서 볼 때, 이와 같은 결과들은 냉동가공이 당근쥬스의 좋은 보존방법임을 시사해 주고 있다.

• 한국초전도ㆍ저온공학회논문지
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• 제15권3호
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• pp.5-8
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• 2013

We have studied Hall effect for potassium (K)-doped $BaFe_2As_2$ superconducting thin films by analyzing the relation between the longitudinal resistivity (${\rho}_{xx}$) and the Hall resistivity (${\rho}_{xy}$). The thin films used in this study were fabricated on $Al_2O_3$ (000l) substrates by using an ex-situ pulsed laser deposition (PLD) technique under a high-vacuum condition of ~$10^{-6}$ Torr. The samples showed the high superconducting transition temperatures ($T_c$) of ~ 40 K. The ${\rho}_{xx}$ and the ${\rho}_{xy}$ for K-doped $BaFe_2As_2$ thin films were measured by using a physical property measurement system (PPMS) with a temperature sweep (T-sweep) mode at an applied current density of $100A/cm^2$ and at magnetic fields from 0 up to 9 T. We report the T-sweep results of the ${\rho}_{xx}$and the ${\rho}_{xy}$ to investigate Hall scaling behavior on the basis of the relation of ${\rho}_{xy}={A{\rho}_{xx}}^{\beta}$. The ${\beta}$ values are $3.0{\pm}0.2$ in the c-axis-oriented K-doped $BaFe_2As_2$ thin films, whereas the thin films with various oriented-directions like a polycrystal showed slightly lower ${\beta}$ than that of c-axis-oriented thin films. Interestingly, the ${\beta}$ value is decreased with increasing magnetic fields.

• 생약학회지
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• 제45권4호
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• pp.275-281
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• 2014

After harvesting the medicinal parts of Curcuma longa, the remaining underground parts were discarded. From the remaining underground parts of Curcuma longa quercetin-3-O-${\beta}$-D-glucopyranoside-7-O-${\alpha}$-L-rhamnopyranoside (Q37) was isolated. The antioxidant activities in vitro and lifespan-extension effect of Q37 were elucidated using the Caenorhabditis elegans. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect of Q37 showed similar potent activities in comparison with vitamin C. Q37 also showed potent superoxide quenching activities as measured by the riboflavin- and xanthine-originated superoxide quenching activity tests. Q37 prolonged lifespan of worms under normal culture condition. In terms of protective effect of Q37 on the stress conditions such as thermal and oxidative stresses, Q37-treated worms exhibited enhanced survival rate, as compared to control worms. To know the possible mechanism of Q37-mediated increased lifespan and stress resistance of worms, we examined the activities of Q37on superoxide dismutase (SOD), and invested intracellular reactive oxygen species (ROS) levels. The results revealed that Q37 was able to elevate SOD activity of worms and reduce intracellular ROS accumulation in a dose-dependent manner.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.551-554
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• 2002

As a general rule, the brazing process between cemented carbides and steel used by Silver (Ag) type brazing filler. The composition of Ag type filler were used Ag-Cu-Zn-Cd type filler mainly. But, the demand of Cadmium (Cd)-free in Ag type filler was raised recently. The reason why Cd-free in Ag brazing filler were occupied to vaporize as a CdO$_2$ when brazing process, because of Cd element was almost low boiling point of all Ag type filler elements. And, CdO$_2$ was a very harmful element for the human body. This experiment was developed Cd-freeing on Ag type filler that was used Indium (In) instead of Cd element. In this experiment, there were changed from 0 to 5% In addition in Ag brazing filler and investigated to most effective percentage of Indium. As a result, the change of In addition instead of Cd, there was a very useful element and obtained same property only 3% In added specimens compared to Cd 19% added specimens. These specimens were obtained same or more deflective strength. In this case, there were obtained 70 MPa over strength and wide brazing temperature range 650-800 C. A factor of deflective strength were influenced by composition and the shape of $\beta$ phase and between $\beta$ phase and cemented carbides interface. Indium element presented as $\alpha$ phase and non-effective factor directly, but it's occupied to solid solution hardening as a phase. $\beta$ phase were composed 84-94% Cu-Ni-Zn elements mainly. Especially, the presence of Ni element in interface was a very important factor. Influence of condensed Ni element in interface layer was increased the ductility and strength of brazing layer. Therefore, these 3% In added Ag type filler were caused to obtain a high brazing strength.