• Korean Chemical Engineering Research
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• 제47권6호
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• pp.795-800
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• 2009

본 연구는 Vortex tube 형 이산화탄소 흡수장치에서 연소배가스 중 $CO_2$ 흡수 특성을 고찰한 것이다. 연소배가스로는 석탄(유연탄)을 연료로 하는 증기발생량 12 ton/hr 규모의 순환유동층 연소보일러에서 발생한 것을 이용하였으며 이산화탄소농도는 11~13 vol% 내외이다. 흡수 용액은 MEA 20 wt%를 기준으로 AMP, HMDA, 강염기계 KOH를 혼합하였다. 본 연구의 목적은 $CO_2$ 흡수장치를 Scrubbing 방식보다 소형화하고, 흡수용액을 절감하는 것이다. 흡수장치는 연소배가스 유량 $20Nm^3/hr$를 처리할 수 있는 직경 17 mm, 길이 250 mm의 Vortex tube 형을 사용하였다. 연소배가스와 흡수용액의 혼합 분무를 통한 $CO_2$ 제거율을 측정하였다. 실험조건은 흡수용액 농도(20~50 wt%), 흡수용액 유량(1.0, $3.0{\ell}/min$)과 연소배가스 유량($6{\sim}15Nm^3/hr$)을 변화시켰다. 결과적으로, MEA에 HMDA를 혼합한 흡수용액의 $CO_2$ 제거율이 가장 우수(약 43% 제거율)하였으며, Vortex tube 장치에서 고속유동의 기 액 접촉효과 및 기 액 분리 특성을 이용하여 $CO_2$ 흡수가 가능하였다. 그러나 $CO_2$ 흡수 효율 향상을 위한 추가적인 공정개발이 요구된다.

• 한국환경과학회지
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• 제21권12호
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• pp.1469-1476
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• 2012

Hydrophilic polymer is suitable as soil conditioners for green roofs that use rainwater, due to promotion of water retention capacity as well as enhancement of the water absorbing capacity. The objective of the present study was to investigate the effects of different levels of hydrophilic polymer concentrations (0, 0.1, 0.2, 0.4, 0.8% w/w) on the water holding capacity and growth response of 6 species in soils amended with hydrophilic polymer in 5 cm of soil thickness on green roofs. The results showed that the water holding capacity of the amended soil improved with increasing amount of applied polymer. The application of 0.8% w/w of the polymer increased the soil moisture by 87% compared to the control, and decreased slowly in green roofs during an arid period. The growth of Sedum spurium 'Dragon's blood' and Lampranthus spectabilis increased significantly and had greater than 60% relative coverage with higher hydrophilic polymer concentrations. However, Juniperus chinensis var. sargentii and Euonymus fortunei var. radicans had no significant differences upon change of hydrophilic polymer concentrations. In Carex kujuzana and Carex morrowii 'Aurea variegata', growth decreased with increase of hydrophilic polymer concentrations. 30 days after planting, Juniperus chinensis var. sargentii, Euonymus fortunei var. radicans, Carex kujuzana, and Carex morrowii 'Aurea variegata' died back due to lowest soil thickness (5 cm), but Sedum spurium 'Dragon's blood' and Lampranthus spectabilis had greater than 90% survival.

• 대한기계학회논문집A
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• 제25권7호
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• pp.1131-1138
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• 2001

This paper concerns the crashworthiness of the widely used vehicle structure, the spot welded hat and double hat shaped section members, which are excellent on the point of the energy absorbing capacity and low production cost. The target of this paper is to analyze the energy absorption capacity of the structure against the front-end collision, and to obtain useful information for designing stage. Changing the spot weld pitches on the flanges, the hat and double hat shaped section members were tested on the axial collapse loads in impact velocities of 4.72m/sec, 6.54m/sec, 7.19m/sec and 7.27m/sec. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA3D. The solutions are compared with results from the impact collapse experiments.

• 한국강구조학회 논문집
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• 제19권1호
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• pp.53-65
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• 2007

새로운 형식의 기둥인 내부 구속 중공 콘크리트 충전 튜브 기둥(내부 구속 중공 CFT 기둥, ICH CFT column ; Internally Confined Hollow CFT Column)의 내진 성능 평가 실험을 수행하였다. 준정적 실험을 통하여 2가지 종류의 ICH CFT 기둥과 일반 중실 RC 기둥의 내진 성능을 비교 평가 하였다. 각각의 기둥 시험체에 대해 최대 하중과 변위의 관계를 측정하였으며, 이를 바탕으로 연성도, 소산에너지, 등가 감쇠비, 손상 지수가 계산되었다. 실험 결과 ICH CFT 기둥은 중실 RC 기둥에 비해 약 2배의 모멘트에 저항을 하였으며, 에너지의 흡수와 소산에서도 1.5배 정도의 성능을 보여주어, ICH CFT 기둥이 일반 중실 RC 기둥보다 더 뛰어난 성능을 가짐을 보여주었다.

• Macromolecular Research
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• 제13권6호
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• pp.483-490
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• 2005

A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan ($_{k}C$), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for $_{k}C$­g-polymethacrylic acid ($_{k}C$-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of super absorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

• 한국수산과학회지
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• 제8권4호
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• pp.208-212
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• 1975

The study was conducted to determine the optimum conditions for keeping quality of shucked sea mussel, Mytilus edulis, during marketing under commercial handling. As quality factors, water holding capacity, pH, VBN and TMA content were measured. Water holding capacity was obviously affected by salt content of the sea mussel meat. Water was released at the salinity above $2.8\%$ and absorbed below the value. In case of distilled water added instead salt solution, $23.3\%$ weight was gained. Absorbing or releasing water of sea mussel meat was also influenced by temperature showing either water gain or loss was greater at, $3^{\circ}C\;than\;25^{\circ}C$. Osmotic quilibrium by salt between meat and liquor was held within 4 hours. The pH value of fresh sea mussle marked 6.0 which is somewhat lower when compared with that of other shellfishes, and it gradually decreased to 5.0 during storage. VBN contents of fresh muscle and shell liquor were $2.1mg\%$ and $1mg\%$ respectively. The sour odour began to be detectable with $5.0mg\%$ of VBN content. TMA in the sea mussel was not detected.

• Metals and materials international
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• 제24권6호
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• pp.1403-1411
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• 2018

Graphene (multilayer graphene) was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to pre-milled Mg by milling in hydrogen (reaction-involving milling). The hydrogen uptake and release properties of the graphene-added Mg were investigated. The activation of Mg-5graphene, which was prepared by adding 5 wt% graphene to Mg pre-milled for 24 h, was completed after the second cycle (cycle number, CN=2). Mg-5graphene had a high effective hydrogen-storage capacity (the quantity of hydrogen absorbed for 60 min) of 6.21 wt% at CN=3 at 593 K in 12 bar $H_2$. At CN=1, Mg-5graphene released 0.46 wt% hydrogen for 10 min and 4.99 wt% hydrogen for 60 min. Milling in hydrogen is believed to create defects (leading to facilitation of nucleation), produce cracks and clean surfaces (leading to increase in reactivity), and decrease particle size (leading to diminution of diffusion distances or increasing the flux of diffusing hydrogen atoms). The added graphene is believed to have helped the sample have higher hydrogen uptake and release rates, weakly but partly, by dispersing heat rapidly.

• Advances in materials Research
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• 제11권3호
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• pp.237-250
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• 2022

The cone bolts with expanded front ends supply improved anchoring performances and increase energy absorbing capacities due to ploughing in the grouted drills. Within this study, use of a novel energy absorber for the cone bolt heads were investigated to assess its design in terms of supplying high support performances. Additionally, different grout material designs were tested to investigate whether the energy absorption capacities of the rock bolts can be improved using a silicone based thermoset polymer (STP) additive. To determine load bearing and energy absorption capacities, a series of deformation controlled pull-out tests were carried out by using bolt samples grouted in rock blocks. According to the results obtained from this study, maximum load bearing capacities of cone bolts are similar and mostly depend on the steel material strength, whereas the energy absorption capacity was determined to significantly vary in accordance with the displacement limits of the shanks. As a result of using STP additive and new polyamide absorber rings, displacement limits without the steel failure increase. The STP additive was found to improve the energy absorption capacities of grouted cone bolts. The absorber rings designed within this study were also assessed to be highly effective and able to double up the energy absorption capacities of the cone bolts.

• Coupled systems mechanics
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• 제4권2호
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• pp.173-189
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• 2015

In reality, masonry infill modifies the seismic response of reinforced concrete (r.c.) frame structures by increasing the overall rigidity of structure which results in: increasing of total seismic load value, decreasing of deformations and period of vibration, therefore masonry infill frame structures have larger capacity of absorbing and dissipating seismic energy. The aim of the paper is to explore and assess actual influence of masonry infill on seismic response of r.c. frame structures, to determine whether it's justified to disregard masonry infill influence and to determine appropriate way to consider infill influence by design. This was done by modeling different structures, bare frame structures as well as masonry infill frame structures, while varying masonry infill to r.c. frame stiffness ratio and seismic intensity. Further resistance envelope for those models were created and compared. Different structures analysis have shown that the seismic action on infilled r.c. frame structure is almost always twice as much as seismic action on the same structure with bare r.c. frames, regardless of the seismic intensity. Comparing different models resistance envelopes has shown that, in case of lower stiffness r.c. frame structure, masonry infill (both lower and higher stiffness) increased its lateral load capacity, in average, two times, but in case of higher stiffness r.c. frame structures, influence of masonry infill on lateral load capacity is insignificant. After all, it is to conclude that the optimal structure type depends on its exposure to seismic action and its masonry infill to r.c. frame stiffness ratio.

• 한국수소및신에너지학회논문집
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• 제5권2호
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• pp.65-71
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• 1994

Electrochemical and thermodynamic properties of $MmNi_5$ and the related alloys for nickel-metal hydride battery(Ni-MH) were studied in terms of the equilibrium hydrogen pressure. $MmNi_5$ alloy with high equilibrium hydrogen pressure(10~20atm at room temperature), which is usually difficult to charge, was substituted for Al in part. Partial substitution of Al made not only the equilibrium pressure to be reduced remarkably, but also the enthalpy change depending on the formation of metal hydride to be agreed to the value in gas phase reaction and electrochemical reaction. Besides the composition of Al which can be given the maximum discharge capacity was turned out to be between the 0.5~1.0 atoms of Al.