• 한국응용과학기술학회지
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• 제27권3호
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• pp.310-317
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• 2010

The electrochemical properties of electric double layer capacitor(EDLC) was studied by controlling pore size distribution and specific surface area of the activated carbon fiber(ACF). The mesoporous ACF, which was prepared by the iron exchange method, showed the tendency of increasing average pore size and decreasing total surface area. The mesoporous ACF (surface area = 2225 $m^2$/g, pore size=1.93 nm) showed increased mesopore(pore size=1~3nm) volume from 0.055 cc/g to 0.408 cc/g compared to its raw ACF. The charging capacity of the EDLC which uses the prepared mesoporous ACF also increased from 0.39 F/$cm^2$ to 0.55 F/$cm^2$. From these results, it can be known that the electrochemical properties of EDLC are mainly dependent on the specific surface area, but above the surface area 2200 $m^2$/g, it is the mesopore volume that affects the performance of the capacitor considerably. Because the increased mesopore volume results in a decreased ion mobility resistance, the charge capacitance is enhanced.

• 대한수의학회지
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• 제27권2호
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• pp.259-267
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• 1987

Enterotoxigenic E. coli (ETEC) cause an acute diarrhea (white scour) in both animals and humans. The disease process initially involves the adherence and colonization of the mucosal surface of the small intestine, followed by the elaboration of a heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (ST). Intestinal adherence or colonization by ETEC is generally mediated by a specific surface-associated pilus (fimbrial) antigen that endows the bacteria with the capacity to adhere to epitherial cell surface. Fourteen monoclonal antibodies (MAbs) directed against pili antigens of ETEC were obtained by cell fusion/hybridoma technique. They were characterized by indirect immunofluorescence assay (IFA), and divided into four groups: specific to K99 antigen (group 1), cross-reactive with K99 and F41 antigens (group 2), specific to K88 antigen (group 3) and specific to 987P and K88 antigens (group 4), respectively. These MAbs demonstrated the distinct pili (K) antigens on the surface of ETEC by IFA, and could be utilized as diagnostic reagent for the identification of ETEC. When eighty-seven field isolates of E. coli from piglet with diarrhea were tested by group 3 MAb, fourty-two strains (48.3%) has K88 pilus antigen suggesting that this is one of the major pilus antigen of ETEC present in fifeld.

• 한국소음진동공학회논문집
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• 제24권8호
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• pp.643-650
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• 2014

Gear transmission system is widely applied in engineering. As the problem of contact fatigue, wear, lubrication failure etc, the condition of gear teeth contacts will be worse. The vibration and sound signals in the gear system will be affected by the some failures like scuffing, abrasive wear and spalling due to the deterioration of gear teeth surface. By studying the estimation of specific film thickness, measurement of reduction in tooth thickness, visual examination of wear mechanisms on the gear teeth and their effects on the statistical parameters of vibration and sound signals, the research obtained the satisfactory results on accessing the surface fatigue wear in a spur gear system. The paper utilizes the relationship between statistical parameters obtained from sound signals and Stribeck curve to confirm the hypothesis of dependency of surface fatigue wear, specific film thickness.

• 한국물환경학회지
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• 제29권4호
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• pp.551-558
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• 2013

The feasibility of water supply as in-stream flow for Mangwall stream was analyzed in terms of water quality and cultivation periphyton using two different types of water resources (e.g., surface water and bank filtration from Han River basin) and three different types of media (e.g., tile, concrete and pebble). The concentrations of organic and inorganic contaminants from the bank filtration were lower than those from surface water by 17.5 - 55.0%. Using water samples collected from Mangwall stream, surface water, and bank filtration, chlorophyll-a, phaeopigment, and growth rate of periphyton were investigated. During 30 day incubation for each water sample, it was observed that filamentous cyanobacteria, Oscillatoriaceae, accounted for 98%, and water velocity of 5 cm/s was optimum for the in situ filamentous cyanobacteria growth. Also, it was deducted for water velocity and chl-a to have an inverse correlation. Meanwhile, the greater the specific surface area of media, the higher the concentration of chl-a. From these results, both water velocity and specific surface area of media should be considered as an combined parameter to deter the growth of filamentous cyanobacteria.

• 한국표면공학회지
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• 제46권5호
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• pp.216-222
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• 2013

In order to improve the performance of electrodeposited diamond-nickel composite, surface modification of diamond particles was carried out using powder immersion reaction assisted coating (PIRAC). Titanium and chromium were selected as coating elements, which are known as carbide former. With respect to the powder elements, various phases were formed on diamond; metallic Ti and TiC for Ti powder, $Cr_3C_2$ for Cr powder, and TiC and $Cr_3C_2$ for Ti-Cr mixed powder. Surface modified diamond particle showed higher specific surface area, especially Ti coating induced considerable increase of specific surface area. The increase of specific surface area suggests increase of surface roughness, and that was confirmed by surface observation using FE-SEM. In addition, wear properties of diamond-nickel composite including surface modified diamonds were improved, and Ti coated diamond showed the highest performance. The wear property of diamond-nickel composite is dependent on adhesion strength between diamond particle and nickel layer. Therefore, surface modification of diamond particle by PIRAC increasing surface roughness is effective to improve the properties of diamond-nickel composite.

• 한국연초학회지
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• 제30권1호
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• pp.8-13
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• 2008

Several activated carbon in different specific surface area was prepared by steam and chemical activation of coconut shell. Products were characterized by BET ($N_2$) at 77K, and probed to be highly specific surface area of $1580m^2/g$ and pore volume that had increased with activating conditions. And also we have analyzed the adsorption efficiency of vapor phase components in cigarette mainstream smoke in order to evaluate the relationship between thesmoke components and the physicochemical properties of activated carbons. As a result of this study, the delivery of mainstream smoke was directly affected by the specific surface area and the pore size of activated carbon. The activated carbon prepared by steam activation exhibited better adsorption efficiency on the vapor phase components in mainstream smoke compared with activated carbon prepared by $ZnCl_2$, due to the higher micro-pore area of 66%. But the adsorption efficiency of semi-volatile matters such as phenolic components in a main stream smoke by the activated mesoporous carbon prepared by $ZnCl_2$ is more effective. From the these results, we can conclude that specific surface area by the micropore area increased the adsorption efficiency of activated carbon on vapour phase components, but semi-volatiles or particulate matter was affected by the ratio of mesopore area in total specific surface area.

• 분석과학
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• 제18권1호
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• pp.74-84
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• 2005

NT, BT 산업의 발달에 함께 계면에서의 흡착특성의 파악은 신물질의 개발이나 공정의 첨단화에서 꼭 필요한 과제가 되고 있다. 체적식 가스흡착방법은 정량적인 흡착량의 측정이 가능하여 비표면적의 표준측정장비로 인식되고 있다. 상용 비표면적 측정장비의 신뢰성 검증을 위하여 인증표준물질을 개발하였고, SI 단위에 소급성을 유지하는 표준장비에 의해 불확도가 평가되었다. 제작된 인증물질은 비표면적이 $10.72{\pm}0.46m^2g^{-1}$ 인 silicon nitride 분말과 $149.50{\pm}3.44m^2g^{-1}$ 인 alumina 분말이다. 이런 검증된 인증물질의 보급은 산업계에 신뢰성 있는 비표면적 측정결과를 줌으로서, 일관성 있는 공정운용에 의한 품질관리, 생산성 향상, 안정성 판단 및 신제품 개발 등에 기여할 것이다.

• 공업화학
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• 제24권6호
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• pp.668-671
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• 2013

본 연구에서는 정수기용 필터로 사용되는 활성탄 블록을 압출 방법으로 제조할 경우 활성탄 블록의 비표면적에 영향을 미치는 고분자 바인더의 특성에 관하여 고찰하였다. 고분자 바인더로 사용되는 Polyethylene의 입자 크기를 변화하여 그에 따른 활성탄 블록의 비표면적의 변화 및 수용액상에서 염소 이온의 흡착 특성을 연구하였다. FE-SEM을 이용하여 PE의 입자 크기 및 입자의 모양을 분석하였으며, 질소 흡 탈착을 이용하여 활성탄 및 활성탄 블록의 비표면적을 측정하였다. 비표면적 측정결과 원료 활성탄은 $1186(m^2/g)$, PE 바인더의 입자크기가 $200{\mu}m$일 때 $444(m^2/g)$, $20{\mu}m$일때 $940(m^2/g)$로 측정되었으며, 필터 성능을 확인하기 위하여 염소 흡착 실험을 실시하여 정수 성능을 평가하였다.

• 한국재료학회지
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• 제28권1호
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• pp.62-67
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• 2018

Active clay, bentonite and zeolite were used as porous materials for humidity controlling ceramic boards. The specific area and the pore volume of active clay were higher than bentonite and zeolite. The flexible strength of the gypsum board decreased with an increasing amount of porous material, and the flexible strength was lowest when active clay with a higher specific surface area than others porous materials was added. The specific surface area and total pore volume of ceramic boards containing porous material were highest at $102.25m^2/g$, $0.142cm^3/g$, respectively, when the active clay was added. In addition, as the amount of added porous materials increased, the specific surface area and total pore volume of the ceramic board increased, but the average pore diameter decreased. The addition of s porous materials with a high specific area and a large pore volume improved the moisture absorptive and desorptive performance of the ceramic board. Therefore, in this experiment, the moisture absorptive and desorptive properties were the best when active clay was added. Furthermore, as the amount of added porous materials increased, the moisture absorptive and desorptive properties improved. When 70 mass% of active clay was added to ${\alpha}$-type gypsum, the hygroscopicity was the highest, about $300g/m^2$, in this experiment.

• Journal of Welding and Joining
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• 제14권4호
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• pp.53-61
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• 1996

It was attempted to improve the wear resistance of Al alloy under the load condition by making a formation of the thicker surface hardening alloy layers. The thicker surface hardening alloy layers were formed on 6061 Al alloys overlayed by MIG and TIG welding process with Cu powders feeding. The characteristics of hardening and wear resistance have been investigated in relation to the microstructures of alloyed layers, with a selection of optimum alloying conditions for formation of overlaying layer. The results obtained were summarized as follows With increasing feeding rate of Cu powders by MIG welding, the hardness and specific wear of the overlay weld alloys were increased. It is considered that these high hardness and specific wear of overlay weld alloys were due to the formation of Θ($Al_2Cu$) phases. With increasing feeding rate of Cu powders by TIG welding, the hardness and specific wear of the overlay weld alloys were increased in feeding rates 12 and 18g/min. However, the hardness and specific wear were decreased in the powder feeding rate 38g/min. It is considered that considered that decrease of hardness and specific wear in the powder feeding rate 38g/min due to formation of ${\gamma}$($Al_4Cu_9$) phases.