• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.57-67
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• 1990

This study is proposed to investigate the effect of electrode preparation method for Alkaline Fuel Cell using NaOH as an electrolyte on the Fuel Cell performance. The materials used for the preparation of electrode are Pt and Ag on Vulcan XC-72. Surface area of Vulcan XC-72 have different values according to the pretreatment conditions and the dispersion of Pt is dependent on the impregnation Particle size of Pt impregnated on unpretreated carbon was observed to be $20{\sim}40{\AA}$ and that on pretreated carbon in $N_2$ stream at $950^{\circ}C$ was found to be finely dispersed less then $15{\AA}$. The electrode performance was affected by the particle size of metals and operating temperature. It was revealed from this study that the optimum particle size about $30{\AA}$ and optimum temperature range is between $90{\sim}100^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
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• 제19권E3호
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• pp.99-120
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• 2003

Visibility impairment in an urban area is mainly caused by airborne fine particulate matters. Visibility in a clean air environment is more sensitive to the change of PM$_{2.5}$ particle concentrations. However, a proportionally larger reduction in fine particle concentration is needed to achieve a small increment of visibility improvement in polluted areas. Continuous optical monitoring of atmospheric visibility and extensive aerosol measurements have been made in the urban atmosphere of Kwangju, Korea. The mean for fine particulate mass from 1999 to 2002 at Kwangju was measured to be 23.6$\pm$20.3 $\mu\textrm{g}$/㎥. The daily average seasonal visual range was measured to be 13.1, 9.2, 11.0, and 13.9 km in spring, summer, fall, and winter, respectively. The mean light extinction budgets by sulfate, nitrate, organic carbon, and elemental carbon aerosol were observed to be 27, 14, 22, and 12%, respectively. It is highly recommended that a new visibility standard and/or a fine particle standard be established in order to protect the health and welfare of general public. Much more work needs to be done in visibility studies, including long-term monitoring of visibility, improvement of visibility models, and formulating integrated strategies for managing fine particles to mitigate the visibility impairment and climate change.e.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.212-217
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• 2010

본 연구에서는 유기현탁제로 폴리비닐알콜(PVA: Poly(vinyl alcohol)을 사용하여 현탁중합토너를 제조하였다. 스타이렌과 부틸아크릴레이트 모노머를 동시에 사용하고 카본블랙을 첨가하여, 좁은 입경분포를 갖는 미세 구형 중합토너를 제조하였다. 최적의 현탁중합조건을 설정하기 위하여 카본블랙이 배제된 예비입자 중합실험을 먼저 수행하였다. 예비입자는 다양한 중합조건에서 제조하였으며, 각각의 특징을 비교 분석하여 최적의 중합조건을 결정하였다. 최적화된 중합조건을 선택하여 제조된 흑색중합토너는 입경 및 형상이 우수하였으며 유리전이온도도 $53.6^{\circ}C$인 것으로 나타나 열적 특성 및 인쇄특성도 우수한 것으로 관찰되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2163-2165
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• 2005

A pulsed laser ablation deposition (PLAD) technique has been used for producing fine particle as well as thin film at relatively low substrate temperatures. However, in order to manufacture and evaluate such materials in detail, motions of plume particles generated by laser ablation have to be understood and interactions between the particles by ablation and gas plasma have to be clarified. Therefore, this paper was focused on the understanding of plume motion in laser ablation assisted by Ar plasma at 50(mTorr). Two-dimensional hybrid model consisting of fluid and particle models was developed and three kinds of plume particles which are carbon atom (C), ion $(C^+)$ and electron were considered in the calculation of particle method It was obtained that ablated $C^+$ was electrically captured in Ar plasmas by strong electric field (E). The difference between motions of the ablated electrons and $C^+$ made E strong and the collisional processes active.

• 한국인쇄학회지
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• 제30권2호
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• pp.1-12
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• 2012

In this experiment, we have manufactured thermal-curable silver pastes for direct printing. And to enhance conductivity, printability, adhesion and hardness during polymer direct-gravure prints, we have manufactured Ag pastes by adding variety of filter contents. Then we have investigated characteristics of rheology in paste according to the gravure printability and the properties of printed conductive patterns. Depending on a variety of Ag powder, there was a big difference in sharpness of printed pattern. And also by the use of carbon, there was a big difference in amount of solvent used, conductivity and in hardness. We could improve doctoring and the sharpness of a pattern by adding Ag paste in carbon particle, but as we have used nano-sized particle, there was an increase in the amount of solvent used and also we have found out that it gives a bad effect as adhesive and hardness becomes weaker. Even though Ag particle has the same spherical shape, the surface treatments could differ from one another. And by the appropriate choice and with the suitable combination of Ag powder, excellent printability and conductivity could be obtained.

• 조명전기설비학회논문지
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• 제20권2호
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• pp.24-28
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• 2006

본 논문은 마이크로 전극 측정 시스템을 사용하여 차세대 신동력 산업인 HEV(Hybrid Electric Vehicle) 및 수소연료전지(PEMFC) 차량용 니켈 수소전지의 전극소재로 사용되고 있는 수소저장합금(Mm : misch metal, $MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$)의 단일 입자에 대해 전기화학적 수소 흡방출 특성 평가를 수행 하였다. 즉 Carbon fiber 마이크로 전극을 합금 입자 한개 위에 전기적인 접촉을 이루도록 조정하고, Cyclic Voltammetry 및 Galvanostatic 충방전 실험을 수행하였다. 그 결과 단일 입자의 방전용량은 약 280[mAh/g]로 이론용량의 약 90[%]의 특성을 보여 주었다. 데이터는. 실제 Ni-MH전지를 구성하는 합금입자 그리고 폴리머 바인더로 구성된 Composite film 전극과 비교 하였다. 추가적으로 합금의 단일 입자에 있어 in situ 미분화 현상을 관찰하였다. 마이크로 전극 측정 시스템에 의한 단일 입자의 전기화학적 평가는 기존의 Composite Film 전극에 비해 수소저장합금에 대해 보다 상세하고 정확한 정보를 쉽게 얻을 수 있었다.

• 조명전기설비학회논문지
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• 제20권2호
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• pp.45-49
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• 2006

본 논문은 마이크로 전극 시스템에 의하여 연료전지 및 Ni-MH 전지로의 응용을 가정한 $AB_5$계 수소저장합금인 $MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$의 단일 입자에 대하여 전기화학적인 평가를 수행하였다. 즉 Carbon fiber 마이크로 전극을 합금 입자 한개 위에 전기적인 접촉을 이루도록 조정하고, 합금 입자 내에서 수소원자의 겉보기 화학적 확산계수를 계산하기 위하여 Potential-Step 실험을 실시하였다. 여기에서 사용되는 합금입자는 치밀하고 전도성이 있는 구형이므로 데이터 해석을 위해 구형확산 모델을 적용하였다. 실험결과로서 겉보기 확산계수($D_{app}$)는 수소 흡장 및 방출되는 전 과정에서 $10^{-9}$과 $10^{-10}[cm^2/s]$ 수준인 것으로 확인되었다. 마이크로 전극 측정 시스템에 의한 단일 입자의 전기화학적 평가는 기존의 Composite Film 전극에 비해 수소저장합금에 대해 보다 상세하고 정확한 정보를 쉽게 얻을 수 있었다.

• 대한토목학회논문집
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• 제4권2호
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• pp.25-33
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• 1984

활성탄(活性炭)의 입경변화(粒徑變化)가 trihalomethane의 흡착(吸着)에 미치는 영향(影響)에 관하여 실험적(實驗的)으로 연구(硏究)하였다. 실험(實驗)에 사용(使用)된 활성탄(活性炭)은 평균입경(平均粒徑)이 0.73mm에서 2.03mm까지의 4종류(種類)이었으며 이들에 대하여 물리적(物理的) 특성(特性)을 조사(調査)하고 trihalomethanedml 흡착능력(吸着能力)을 등온흡착실험(等溫吸着實驗)과 micro-column 실험(實驗)을 통해 밝혀냈다. 입경(粒徑)의 증가(增加)에 따라 비표면적(比表面積)이 감소(減少)하였고 활성탄(活性炭) 내부공극(內部空隙)의 반경(半徑)이 크게 증가(增加)하였다. 또한 큰 입자(粒子)의 경우에는 공극(空隙)의 크기가 넓게 분포(分布)하였다. Trihalomethane의 흡착(吸着)은 Freundlich 공식(公式)에 의해 잘 표현(表現)되었고 입경증가(粒徑增加)에 따라 흡착능력(吸着能力)의 감소(減少)가 뚜렷하게 나타났다. Micro-column 실험결과(實驗結果)와 모형(模型)의 Simulation으로부터 물질도달계수(物質導達係數)와 내부표면광산계수(內部表面壙散係數)를 산정(算定)하였다. 입경변화(粒徑變化)에 따른 계수(係數)의 변화(變化)는 무시(無視)할 수 있었으며 입경변화(粒徑變化)에 따른 효율(効率)의 차이(差異)는 주로 흡착능력(吸着能力)의 차이(差異)에서 오는 결과(結果)로 판단(判斷)된다.

• 한국입자에어로졸학회지
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• 제18권3호
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• pp.79-86
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• 2022

Many commercial air purifiers currently have deployed granular activated carbon (GAC) filters for removing volatile organic compounds in the indoor air. GACs are generally used to remove gaseous contaminants in the air through adsorption by the inner surfaces of pores. In addition, airborne particles can be also filtered by the surface adsorption of the GACs, which can improve the life-time of the particulate filters. In this study, the filtration efficiency of GACs to ultrafine particles through surface adsorption was investigated at different volume flow rates by deploying a continuous particle filtration system. The polydisperse sodium chloride (NaCl) particles were generated by a set of an atomizer and a diffusion dryer, and then mixed with particle-free air at different volume flow rates. The penetration of ultrafine particles and pressure drop for each experimental condition were measured to figure out the effect of the volume flow rate on the surface adsoprtion of the GACs to particles, ~ 2 mm. The particle filtration efficiency of the GACs decreased as the volume flow rate increased from 4 to 14 lpm. However, the 5 times thicker GAC filter layer decreased the penetration of ultraparticles than a preious study. The filtration efficiency of the single granule was also higher than the previous result in the literature with smaller granule filter materials.

• Carbon letters
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• 제26권
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• pp.11-17
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• 2018

Milled carbon fiber (mCF) was prepared by a ball milling process, and X-ray diffraction (XRD) diffractograms were obtained by a $2{\theta}$ continuous scanning analysis to study mCF crystallinity as a function of milling time. The raw material for the mCF was polyacrylonitrile-based carbon fiber (T700). As the milling time increased, the mean particle size of the mCF consistently decreased, reaching $1.826{\mu}m$ at a milling time of 18 h. The XRD analysis showed that, as the milling time increased, the fraction of the crystalline carbon decreased, while the fraction of the amorphous carbon increased. The (002) peak became asymmetric before and after milling as the left side of the peak showed an increasingly gentle slope. For analysis, the asymmetric (002) peak was deconvoluted into two peaks, less-developed crystalline carbon (LDCC) and more-developed crystalline carbon. In both peaks, Lc decreased and $d_{002}$ increased, but no significant change was observed after 6 h of milling time. In addition, the fraction of LDCC increased. As the milling continued, the mCF became more amorphous, possibly due to damage to the crystal lattices by the milling.