• Elastomers and Composites
• /
• 제44권1호
• /
• pp.22-33
• /
• 2009

최근에 나노충전제를 낮은 부피 분율로 보강한 엘라스토머-나노복합체는 흥미 있는 물성 때문에 관심을 크게 불러 일으켰다. 특히 층화 규산염 클레이(clay), 카본 나노튜브(carbon nanotube), 나노섬유, 탄산칼슘, 금속 산화물 또는 실리카 나노입자 등과 같은 나노충전제를 탄성체에 혼입하면 기계적 물성, 내열성, 동적 기계적 물성, 화염지연성, 차단성 등이 크게 향상된다. 나노복합체의 물성은 크게 고분자 기질, 나노충전제의 성질과 이들의 혼입 방법에 좌우한다. 탄성체 기질 내에 나노충전제들의 균일한 분산은 원하는 물리적 특성과 기계적 특성을 얻기 위한 일반적 필수조건이다. 본 논문은 층화 규산염, 실리카(silica), 카본 나노튜브(carbon nanotube), 나노섬유와 여러 가지 다른 나노입자로 보강된 탄성체 나노복합체의 현재 개발 현황을 소개하였다.

• Journal of Preventive Medicine and Public Health
• /
• 제34권1호
• /
• pp.41-46
• /
• 2001

Objectives : To investigate the effects of particulate matter (PM), a marker of environmental pollution derived from combustion sources, on lung epithelial cells (A549) and macrophage (RAW 264.7). Methods : The production of reactive radicals from lung cells, the lipid peroxidation of cell membrane, and the cytotoxicity of PM were measured using an in vitro model. The results were compared with a control group. Results : The presence of PM significantly increased the production of reactive oxygen species and reactive nitrogen species with time and in a dose dependent pattern and also increased the malondialdehyde concentration in lung epithelial cells. The cytotoxicity of PM was increased with increasing concentration of PM. Conclusions : It has been suggested that urban particulate matter causes an inflammatory reaction in lung tissue through the production of hydroxyl radicals, nitric oxides and numerous cytokines. The causal chemical determinant responsible for these biologic effects are not well understood, but the bioavailable metal in PM seems to determine the tonicity of inhaled PM.

• 한국재료학회지
• /
• 제13권8호
• /
• pp.537-542
• /
• 2003

($Y_{l-x}$ $Gd_{x}$ )$O_2$$_3$: $Eu^{ 3＋}$ red phosphors were prepared with the solvothermal synthesis using the 2-methoxy-ethanol solvents and the emission intensity was investigated that applied with the 254 nm wavelength and the maximum excitation wavelength for energy source. The used solvents for the solvothermal synthesis were made of nitrate salt solutions of Y, Gd and Eu. These solutions dropped in autoclave have be reacted with the solvothermal synthesis at $200^{\circ}C$ for 5hrs and the red phosphors prepared here in were showed the pure cubic phase after annealing at $1000∼1200^{\circ}C$. The brightness of ($Y_{l-x}$ $Gd_{x}$)$_2$$O_3$: $Eu^{3＋}$ phosphors particles was increased as an increase of Gd ratio. The maximum excitation wavelengths of ($Y_{l-x}$ $Gd_{x}$ )$_2$$O_3$: $Eu^{3＋}$ / phosphors particles were increased according to increasing Gd ratio from 253 nm to 259 nm wavelength. The maximum emission intensity of $Gd_2$$O_3$: $Eu^{3＋}$ (Y/Gd = 1/0) phosphors particles under UV 259 nm was found to be higher than the commercial product of $Y_2$$O_3$: $Eu^{3＋}$ phosphors.

• Transactions on Electrical and Electronic Materials
• /
• 제1권3호
• /
• pp.14-17
• /
• 2000

Giga bit dynamic random access memory(DRAM) requires the capacitor of high dielectric films. Some metal oxides films have been proposed as the dielectric material . And Pt is one of the most promising electrode materials. However very little has been done in developing the etching technologoy Pt film. Therefore, it is the first priority to develop the technology for plasma etching of Pt film. In this study, the dry etching of Pt film was investigated in Inductively Coupled Plasma(ICP) etching system with Cl$_2$/Ar and HBr/Cl$_2$/Ar gas mixing. X-ray photoelectron spectroscopy (XPS) was used in analysis of sidewall residues for the understanding of etching mechanism. We found the etch residues on the pattern sidewall is mainly Pt-Pt, Pt-Cl and Pt-Br compounds, Etch profile was observed by Scanning Electron Spectroscopy(SEM) . The etch rate of Pt film at 10%, Cl$_2$/90% Ar gas mixing ration was higher than at 100%. Ar. Addition of HBr to Cl$_2$/Ar as an etching gas led to generally higher selectivity to SiO$_2$. And the etch residues were reduced at 5% HBr/5% Cl$_2$/90% Ar gas mixing ration. These pages provide you with an examples of the layout and style which we wish you to adopt during the preparation of your paper, Make the width of abstract to be 14cm.

• 전기학회논문지
• /
• 제66권2호
• /
• pp.357-362
• /
• 2017

Among the lithium metal oxides for asymmetric hybrid supercapacitor, $Li_4Ti_5O_{12}(LTO)$ is an emerging electrode material as zero-stain material in volume change during the with the charging and discharging processes. The pulverized LTO powder was observed to show the enhanced capacity from 120 mAh/g to 156 mAh/g at C-rate (10, 100 C). Hybrid supercapacitor module(48V, 416F) was fabricated using an asymmetric hybrid capacitor with a capacitance of 7500F. As a result of the measurement of C-rate characteristics, the module shows that the discharge time is drastically reduced at more than 50C, and the ESR and voltage drop characteristics are increased. The energy density and power density were reduced under high C-rate conditions. When designing asymmetric hybrid supercapacitor module, the C-rate and ESR should be considered As a result of measuring the 5 kw UPS, it was discharged at the current of 116A~170A during the discharge in the voltage range of 48V~30V, and the compensation time at discharge was measured to be about 33.2s. Experimental results show that it can be applied to applications related to stabilization of power quality by applying hybrid supercapacitor module.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2007년도 추계학술대회 논문집
• /
• pp.61-62
• /
• 2007

HVOF thermal spray coating of micron size Co-alloy powder has been studied for the durability improvement of high velocity spindle (HVS). Optimal coating process of this system for the best surface properties is hydrogen flow rate 75 FMR, oxygen flow rate 38-42 FMR, feed rate 30 g/min at spray distance 5 inch. Friction coefficient (FC) and wear trace (WT) decrease increasing coating surface temperature from 25$^{\circ}$C to 538$^{\circ}$C due to the higher lubricant effects of the oxides at the higher temperature. At the study of adhesion of T800 coating on a light metal alloy Ti-6Al-4V (Ti64) tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64/T800 are 8,740 psi and near middle of T800 coating respectively. This shows that adhesion of Ti64/T800 is higher than the cohesion strength (8,740 psi) of T800 coating. Therefore T800 coating is strongly advisable for the surface coating on HVS such as high speed air-bearing spindle.

• 자원리싸이클링
• /
• 제1권1호
• /
• pp.44-50
• /
• 1992

소규모공장 규모의 알카리 및 산공정법에 의해 철강의 산세 폐액으로부터 $\alpha$-FeOOH를 제조하였으며, 이 때 합성된 분체를 TEM, SEM, TG-DTA, XRD, VSM 및 화학분석으로 물성을 조사하였다. 실험결과에 의하면, $\alpha$-FeOOH의 제조에 있어서 알카리 공정의 반응 시간이 짧으며, 제조된 분체는 약 $0.5\mu\textrm{m}$의 크기로 침상을 나타내었다. 또한 제조 방법에 따라 $\alpha$-FeOOH 와 $\alpha-Fe_2O_3$가 생성되며 이들은 미려한 황색 및 적색을 띠고 있었고 $\alpha-Fe_2O_3$를 $370^{\circ}C$의 수소 분위기에서 1시간 환원하면 367(Oe) 및 86.7 (emu/g)의 자성을 갖는 $Fe_3O_4$ 가 얻어질 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.533-533
• /
• 2007

The stress effect of SiGe p-type metal oxide semiconductors field effect transistors(MOSFETs) has been investigated to compare device properties using Si bulk and partially depleted silicon on insulator(PD SOI). The electrical properties in SiGe PD SOI presented enhancements in subthreshold slope and drain induced barrier lowering in comparison to SiGe bulk. The reliability of gate oxides on bulk Si and PD SOI has been evaluated using constant voltage stressing to investigate their breakdown (~ 8.5 V) characteristics. Gate leakage was monitored as a function of voltage stressing time to understand the breakdown phenomena for both structures. Stress induced leakage currents are obtained from I-V measurements at specified stress intervals. The 1/f noise was observed to follow the typical $1/f^{\gamma}$ (${\gamma}\;=\;1$) in SiGe bulk devices, but the abnormal behavior ${\gamma}\;=\;2$ in SiGe PD SOI. The difference of noise frequency exponent is mainly attributed to traps at silicon oxide interfaces. We will discuss stress induced instability in conjunction with the 1/f noise characteristics in detail.

• 한국재료학회지
• /
• 제15권1호
• /
• pp.31-36
• /
• 2005

It is well known that PCB (Printed Circuit Board) is a complex mixture of various metals mixed with various types of plastics and ceramics. In this study, high temperature pyre-metallurgical process was investigated to extract valuable metallic components from the PCB scrap. For this purpose, PCB scrap was shredded and oxidized to remove plastic materials, and then, quantitative analyses were made. After the oxidation of the PCB scrap, $30.6wt\%SiO_2,\;19.3wt\%Al_2O_3\;and\;14wt{\%}CaO$ were analyzed as major oxides, and thereafter, a typical composition of $32wt\%SiO_2-20wt\%Al_2O_3-38wt{\%}CaO-10wt\%MgO$ was chosen as a basic slag system for the separation of metallic components. Moreover a size effect of crushed PCB scrap was also investigated. During experiments a high frequency induction furnace was used to melt and separate metallic components. As a result, it was found that the size of oxidized PCB scrap was needed to be less 0.9 m to make a homogeneous liquid slag and to recycle metallic components over $95\%$.

• 한국산학기술학회논문지
• /
• 제22권5호
• /
• pp.554-560
• /
• 2021

크러드는 원자력 발전소 운전 시 핵연료 표면에 침적되는 철-니켈-크롬 등의 금속 산화물로 이루어진 다공성 물질이다. 그 두께는 수십 ㎛ 수준이다. 발전소의 냉각재상실사고 시 크러드 층은 핵연료-냉각수 열전달에 영향을 미치게 되어 원전 안전성 측면에서 그 영향을 살펴보는 것이 중요하다. 일반적으로 크러드는 열저항으로 인하여 핵연료 온도를 높이는 부정적 효과가 있는 것으로 알려져 있었다. 그 이유는 크러드에 의하여 핵비등, 최소막비등온도, 단상증기 열전달, 임계열유속, 막비등 열전달 등 2상유동 열전달 특성을 고려하지 않았기 때문이다. 본 연구에서는 다공성 크러드 물질의 물성치를 모델링하고 이를 국내 원전안전해석 코드인 SPACE에 탑재하였다. 크러드는 다공성 고체 물질이고 표면이 거칠기 때문에 최소막비등온도와 단상증기 열전달이 증가할 것으로 예상된다. 이에 최소막비등온도와 단상증기 열전달이 최대 피복재 온도 및 급냉에 미치는 영향을 평가하였다. 시험 계산은 기존 FLECHT-SEASET 재관수 실험 장치에 기반으로 수행되었다. 계산결과 최소막비등온도가 상승하여 급냉시간이 줄어들었다. 단상증기 열전달의 경우 약 20% 증가할 때까지는 최대 피복재 온도가 하강하였다. 크러드 층이 원전 안정성 측면에서 긍정적인 효과가 있음을 확인하였다.