• 원예과학기술지
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• 제19권2호
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• pp.179-185
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• 2001

원예용 배지의 물리화학적 특성을 파악하기 위해 전세계적으로 다양한 분석 방법이 사용되고 있다. 유럽은 배지 분석방법의 표준화 연구를 지속적으로 수행해왔다. 유럽표준화 위원회에서는 유럽표준방법으로 CEN methods를 최종안까지 제출하였으며 사실상 유럽표준 배지분석방법의 제정을 확립하는 단계에 있다. 물리적 특성 중 건물함량과 수분함량은 건조 후 분석하였고, 실험 가밀도는 일정한 부피에 채워진 시료의 무게로 측정하였다. 가밀도, 진밀도, 공극률, 액상, 기상, 부피 감소율은 double ring과 sand suction table이라는 장치를 사용하여 배지를 포화, 배수시킨 후 건조시켜 분석하였다. 화학적 특성 중 pH와 EC는 부피 기준 1:5로 침출하여 분석하였다. 유기물과 회분함량은 건조와 연소 과정을 통해 분석하였다. CEN methods는 유럽표준방법으로 확립을 앞두고 있으나 더 지속적인 연구가 필요할 것이다.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.585-591
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• 2011

This study has focused on the development of high performance membrane-electrode assemblies (MEAs) fabricated by decal method for proton exchange membrane fuel cell (PEMFC). To study the effect of ionomer contents on performance, we fabricated MEAs with several electrodes which were prepared by varying the quantity of ionomer from 20 wt.% to 45 wt.% in catalyst layer. The MEA performance was obtained through single cell test. The MEA prepared from electrode with 25wt.% of ionomer showed the best performance. We evaluated the surface area and pore volume of electrode with BET. We found that the surface area and pore volume in electrode decreased rapidly at the electrode with 40wt.% of ionomer in catalyst layer. MEA was fabricated by roll laminator machine and the roll laminating conditions for the preparation of MEA, such as laminating press, temperature and speed, were optimized. The MEA performance is not affected by laminating temperature and speed, but roll laminating press have a great effect on MEA performance.

• 한국대기환경학회지
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• 제32권2호
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• pp.176-183
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• 2016

Activated carbon fibers (ACFs) for $CO_2$ adsorption were prepared from polyacrylonitrile (PAN) fiber through the systematic processes such as oxidation, activation and amination with the focus on the formation of nitration functional groups. Textural analysis of test samples revealed the decrease of specific surface area and pore volume by chemical activation including amination. The ratio of micropores to the total volume was 0.85 to 0.91, which was high enough with the pore size of 1.57 to 1.77 nm. Nitrogen compounds such as imine, pyridine and pyrrole presenting favorable interforces to $CO_2$ molecules were formed throughout the whole preparation steps. The aminated ACF adsorbent showed the enhanced adsorption capacity, 0.40 mmol/g for low-level $CO_2$ flow (3000 ppm) at room temperature. Selectivity of $CO_2$ against dry air ($O_2$ & $N_2$) also increased from 1.00 to 4.66 by amination.

• 콘크리트학회논문집
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• 제15권2호
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• pp.273-279
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• 2003

본 연구에서는 MMA/BA 합성 라텍스를 이용하여 폴리머 시멘트 모르타르의 성질에 영향을 미치는 모노머비의 효과를 검토하고, 시멘트 혼화용 폴리머로서의 개발적용을 위해 필요한 기초적 실험 데이터를 얻기 위한 것이다. 실험결과, MMA/BA모노 머비에 따른 폴리머 시멘트 모르타르의 세공경 분포는 MMA/BA의 비가 60 : 40, 70 : 30에서 미세공극량이 크게 증가했으며, 전세공용적은 감소하였다. 또한 모노머비에 관계없이 폴리머 시멘트 비가 증가할수록 그 효과는 더욱 커지는 것으로 나타났다. 일반적으로 MMA/BA 혼입 폴리머 시멘트 모르타르의 압축강도는 MMA 결합재량 70% 및 폴리머-시멘트비 15%에서 가장 우수하게 나타났으며, 흡수율과 염화물 이온 침투저항성은 MMA 결합재량보다는 폴리머-시멘트비에 의해 크게 지배되는 것으로 나타났다. 모노머비를 변화한 MMA/BA 합성 라텍스 혼입 폴리머 시멘트 모르타르의 성질에 영향을 미치는 중요한 인자는 MMA 결합재량의 변화에 의한 세공경분포의 변화와 폴리머-시멘트비로 나타났다.

• 소성∙가공
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• 제18권4호
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• pp.296-303
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• 2009

The effect of porosity on the high-cycle fatigue properties of Al-Si-Mg casting aluminum alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both Al-Si-Mg casted (F) and heat-treated (T6) conditions. Porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The microstructure observation results showed that eutectic Si particles were homogeneously dispersed in the matrix of the Al-Si-Mg casting alloys, but there were porosities formed as cast defects. The high-cycle fatigue results indicated that the fatigue strength of the 356-T6 alloy was higher than that of the 356-F alloys because of the significant reduction in volume fraction of pores by heat treatment. The SEM fractography results showed that porosity affected detrimental effect on the fatigue life: 80% of all tested samples fractured as a result of porosity which acted as the main crack initiation site. It was found that fatigue life decreased as the size of the surface pore increased. A comparison was made between surface pore and inner pore for its effect on the fatigue behavior. The results showed that the fatigue strength with the inner pores was higher than that of the surface pore.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.350-352
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• 2009

The effect of porosity on the high-cycle fatigue properties of Al-Si-Mg casting aluminum alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both Al-Si-Mg casted (F) and heat-treated (T6) conditions. Porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The microstructure observation results showed that eutectic Si particles were homogeneously dispersed in the matrix of the Al-Si-Mg casting alloys, but there were porosities formed as cast defects. The high-cycle fatigue results indicated that the fatigue strength of the 356-T6 alloy was higher than that of the 356-F alloys because of the significant reduction in volume fraction of pores by heat treatment. The SEM fractography results showed that porosity affected detrimental effect on the fatigue life: 80% of all tested samples fractured as a result of porosity which acted as the main crack initiation site. It was found that fatigue life decreased as the size of the surface pore increased. A comparison was made between surface pore and inner pore fur its effect on the fatigue behavior. The results showed that the fatigue strength with the inner pores was higher than that of the surface pore.

• 한국연초학회지
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• 제18권1호
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• pp.85-91
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• 1996

Commercially available activated carbon was treated with 0.2N NaOH/0.1N HCl to decrease the ash contents and to analyze the effect of demineralization. We have studied their properties and adsorptivity to solvents such as benzene, acetone, toluene and carbon tetrachloride, ammonia and also aldehydes of cigarette smoke. By demineralization with NaOH/HCl, surface area and pore volume were increased up to 10 - 20% according to developement of micro-pore and pH of activated carbon was also changed from 10.2 to 6.3. Surface acidity of the activated carbon treated with chemicals increased slightly. The chemical treatment led to small increase in adsorptioil properties of solvents, ammonia and aldehydes of cigarette smoke, but content of chlorine and sulfur in activated carbon were reduced. As the results of smoking test, charcoal taste caused by the activated carbon was reduced significantly by the treatment with NaOH/HCl.

• Carbon letters
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• 제4권3호
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• pp.140-145
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• 2003

Antibacterial behaviors of PAN-based activated carbon fibers (ACFs) containing silver metal were investigated. The effects of surface and pore structures of the ACFs were studied by $N_2$/77 K adsorption and D-R plot as a function of silver loading content. The antibacterial activities were investigated by a dilution test against Staphylococcus aureus (S. aureus; gram positive) and Klebsiella pnemoniae (K. pnumoniae; gram negative). As experimental results, the ACFs showed some decreases in specific surface areas, micropore volumes, and total pore volume with an increase of silver content. However, the antibacterial activities of the ACFs were strongly increased against S. aureus as well as K. pnumoniae, which could be attributed to the presence of antibacterial metal in the ACFs system.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1517-1521
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• 2009

A variation of pore structure of shotcrete matrix was experimented by Mercury Intrusion Porosimetry, and the relation with compressive strength was also examined. As a result of the Mercury Intrusion Porosimetry(MIP) test, RM-P1 Batch the macropore diameter of the RM-BFS2 and RM-BFS3 Batch than to have a relatively macropore can see a lot of long-term durability performance degradation. Also, K and N Batch the current is applied to the mine if the factors on shotcrete durability performance of the macropore volume of the entire appears to be a long-term durability performance in the fall.

• 공업화학
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• 제8권6호
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• pp.979-984
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• 1997

폴리머 혼화제로서 styrene-butadiene rubber(SBR)라텍스, ethylene-vinyl acetate(EVA)에멀젼 및 polyacrylic ester(PAE)에멀젼을 사용하여 동일한 스럼프에서 폴리머-시멘트비를 변화시켜 공시체를 제조하여, 압축과 휨강도시험, 흡수시험, 세공분포측정 및 미세구조 관찰 등을 실시하였다. 그 결과 폴리머-시멘트비의 증가와 더불어 압축과 휨강도 모두 향상되었고, 동해에 큰 영향을 주는 모세관 공극범위의 세공량은 감소되었으며, 폴리머 시멘트비 15wt% 이상에서 연속적인 폴리머필름이 형성되었다.