• 대한환경공학회지
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• 제28권4호
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• pp.384-388
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• 2006

본 연구는 극성 및 독성물질에 대한 활성탄의 흡착력을 향상시키기 위하여, 활성탄을 산 처리 후 활성탄 50 g에 0.1 M $FeSO_4{\cdot}7H_2O,\;CuSO_4{\cdot}5H_2O,\;AgNO_3$ 용액을 300 mL 첨가하여 jar tester를 이용하여 60 rpm의 속도로 1시간 교반시켜 철, 은, 구리 이온을 첨착하였다. 금속 첨착과정으로 제조한 금속 첨착활성탄의 표면 성상 및 화학적 특성을 규명하기 위하여 비표면적, 세공용적 및 분포, 주사현미경 촬영, 흡착등온 등의 실험을 하였다. 산 처리 활성탄에 철, 구리, 은을 첨착할 경우 미세세공이 중간세공과 거대세공으로 전환되어 금속 첨착량이 약 1.3배 정도 증가하였고 금속 첨착활성탄내에서 미세세공에 의한 물리적 흡착과 침착된 금속 이온에 의한 화학적 흡착이 동시에 가능하였다.

• 한국응용과학기술학회지
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• 제22권1호
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• pp.43-49
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• 2005

OXI-PAN fibers, Kynol fibers and rayon fibers were used as precursorsfor the preparation of activated carbon fibers (ACFs) by chemical activation with KOH at $800^{\circ}C$. The effects of different precursorfibers and fiber/KOH ratios on the final ACFs are discussed. The precursor fibers used are appropriate for the ACFs in a single stage pyrolysis process. The OXI-PAN fibers which were activated with KOH of 2.0M showed a specific surface area of $2328m^2/g$ however, loosed the fiber shape because of low yields. The Kynol fibers and Rayon fibers showed the high yields but the lower specific surface area of $900m^2/g$ and $774m^2/g$, respectively, at KOH of 1.5M. The OXI-PAN fibers which were activated with KOH of 1.5M have a specific surface area of $1028m^2/g$ and higher micro-pore volumes and lower yields rather than Kynol-1.5 and Rayon-1.5 samples. This phenomenon is because of higher chemical resistance of the Kynol and Rayon fibers rather than OXI-PAN fibers. However, the Kynol fibers were the best precursors on KOH activation at $800^{\circ}C$ considered carbon yields, surface areas and micropore volumes.

• 상하수도학회지
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• 제32권1호
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• pp.47-53
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• 2018

This study investigated phosphorus removal from secondary treated effluent using coagulation-membrane separation hybrid treatment to satisfy strict regulation in wastewater treatment. The membrane separation process was used to remove suspended phosphorus particles after coagulation/settlement. Membrane separation with $0.2{\mu}m$ pore size of micro filtration membrane could reduce phosphorus concentration to 0.02 mg P/L after coagulation with 1 mg Al/L dose of polyaluminum chloride (PACl). Regardless of coagulant, the residual concentration of phosphorus decreased as the dose increased from 1.5 to 3.5 mg Al/L, while the target concentration of 0.05 mg P/L or less was achieved at 2.5 mg Al/L for the aluminum sulfate (Alum) and 3.5 mg Al/L for PACl. Moreover, alum showed better membrane flux as make bigger particles than PACl. Alum showed a 40% of flux decrease at 2.5 mg Al/L dose, while PACl indicated a 50% decrease of membrane flux even with a higher dose of 3.5 mg Al/L. Thus, alum was more effective coagulant than PACl considering phosphorus removal and membrane flux as well as its dose. Consequently, the coagulation-membrane separation hybrid treatment could be mitigate regulation on phosphorus removal as unsettleable phosphorus particles were effectively removed by membrane after coagulation.

• Carbon letters
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• 제28권
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• pp.116-120
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• 2018

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature ($600-850^{\circ}C$) on the $CO_2$ adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of $1488m^2g^{-1}$ was achieved at an activation temperature of $800^{\circ}C$ (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to $850^{\circ}C$. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, $CO_2$ adsorption isotherms showed that AC-800 exhibited the best $CO_2$ adsorption capacity of $110mg\;g^{-1}$ at 298 K and 1 bar.

• 대한기계학회논문집B
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• 제24권3호
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• pp.402-410
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• 2000

As the combustion process of CWM consists of the water evaporation, the release and combustion of volatile matter, and the combustion of char for every particle, it is more complex than that of existent liquid fuel. Though the many studies on CWM combustion have been carried out by the single droplet using hanging methods or the multiple droplet using atomization methods, any report don't presents definite solution about the effects by the initial water evaporation and combustion of volatile. When CWM is suddenly exposed in the high temperature surroundings, the internal water evaporates and then each droplet builds up pores. Besides, porosity rate changes along the temperature of surroundings, the composition ratio of CWM, and the initial diameter of droplet. In result, because it affects the whole combustion rate, the combustion of CWM has complex mechanism as compared with the combustion of liquid or gas fuel. Therefore, concentrating on porous structure of CWM, this study has proceeded to acquire the basic data on the CWM injection combustion and closely examines the effects of the first stage combustion on the whole combustion by measuring the diameter variations, pore rate, mass fraction burned, and the internal temperature changes of CWM droplet. The results demonstrate that $60{\sim}70%$ of initial mass is reduced during water evaporation and volatile combustion period, and swelling rate, mass faction burned, and density variation are greatly concerned with atomization of CWM etc.

• 한국기계가공학회지
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• 제15권5호
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• pp.86-92
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• 2016

In this study, we used a polymer deposition system, based on fused deposition modeling, to fabricate the 3D scaffold and then fabricated micro-pores on a 3D scaffold using a salt leaching method. Materials included polycaprolactone (PCL) and sodium chloride (NaCl). The 3D porous scaffolds were fabricated according to blending ratio such as PCL (70 wt%)/NaCl (30 wt%) and PCL (50 wt%)/NaCl (50 wt%). The 3D porous scaffolds were observed by scanning electron microscopy. The results showed that 3D porous scaffolds had a deposition width of $500{\mu}m$, contained a pore size of $500{\mu}m$ and below $100{\mu}m$. To evaluate the 3D porous scaffolds for bone tissue engineering, we carried out the cell proliferation experiment using a CCK-8 and a mechanical strength test using a universal testing machine. In summary, the 3D porous scaffold was found to be suitable for cancellous bone of human in accordance with the result of in-vitro cell proliferation and mechanical strength. Thus, a 3D porous scaffold could be a promising approach for effective bone regeneration.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• Journal of the Korean Wood Science and Technology
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• 제38권3호
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• pp.205-212
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• 2010

본 연구는 홀로셀룰로오스를 이용하여 제조한 에어로겔과 에어로겔의 열적특성 및 다공성에 대해서 검토하였다. 홀로셀룰로오스는 alkali hydroxide-urea 용액으로 용해 및 겔화시켜 동결건조로 에어로겔을 제조하였다. 홀로셀룰로오스 에어로겔은 그물모양 또는 스폰지와 같은 다공성구조로 이루어졌다. 밀도는 0.04g/$cm^3$이었고, 비표면적은 145.3 $m^2$/g이었다. 에어로겔의 열분해는 $210{\sim}350^{\circ}C$의 온도범위에서 일어났으나,저속의 승온조건일수록 열분해가 보다 낮은 온도에서 일어났다. 홀로셀룰로오스 에어로겔은 승온조건이 저속일수록 micro pore체적이 증가하였다. 홀로셀룰로오스 에어로겔 탄화물의 비표면적은$0.5^{\circ}C$/min의 승온조건이 656.7 $m^2$/g로 가장 높았다. 탄화물들은 에어로겔의 구조가 열에 의해 섬유의 배열이 변형되어 불규칙적 구조로 변화된 것이 주사전자현미경에 의해 관찰되었다.

• 콘크리트학회논문집
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• 제21권5호
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• pp.639-647
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• 2009

바닷물에 의한 염해와 동결융해 환경에 노출된 철근 콘크리트구조물의 내구성을 평가하기 위해서는 콘크리트의 미세구조적 특성 및 염화물 침투성에 대한 콘크리트의 확산 저항성을 동시에 분석하는 것이 중요하다. 이 연구에서는 고로슬래그 미분말(GGBS)을 혼합한 콘크리트에 대하여 수은압입법(MIP)에 의해 얻어진 콘크리트의 미세공극 구조와 장기 및 단기 재령의 염화물 확산성과의 상관성에 대하여 연구하였다. 물시멘트비는 40, 45, 50%로 변화시키고, 단위시멘트량을 300, 350, 400, 450 kg/$m^3$으로 변화시킨 OPC 및 GGBS 콘크리트 시편에 대하여 동결융해에 의해 손상된 GGBS 콘크리트에서의 확산성과 미세구조의 변화를 관찰하였다.

• 한국재료학회지
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• 제27권9호
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• pp.495-500
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• 2017

Oxide layers were formed by an environmentally friendly plasma electrolytic oxidation (PEO) process on AZ91 Mg alloy. PEO treatment also resulted in strong adhesion between the oxide layer and the substrate. The influence of the KF electrolytic solution and the structure, composition, microstructure, and micro-hardness properties of the oxide layer were investigated. It was found that the addition of KF instead of KOH to the $Na_2SiO_3$ electrolytic solution increased the electrical conductivity. The oxide layers were mainly composed of MgO and $Mg_2SiO_4$ phases. The oxide layers exhibited solidification particles and pancake-shaped oxide melting. The pore size and surface roughness of the oxide layer decreased considerably with an increase in the concentration of KF, while densification of the oxide layers increased. It is shown that the addition of KF to the basis electrolyte resulted in fabricating of an oxide layer with higher surface hardness and smoother surface roughness on Mg alloys by the PEO process. The uniform thickness of the oxide layer formed on the Mg alloy substrates was largely determined by the electrolytic solution with KF, which suggests that the composition of the electrolytic solution is one of the key factors controlling the uniform thickness of the oxide layer.