• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.212-216
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• 2021

We investigated the feasibility of hydrogen storage with electrochemically formed VO₂ nanotubes. The VO₂ nanotubes were fabricated through the anodization of vanadium metal in fluoride ion-containing organic electrolyte followed by an annealing process in an Ar-saturated atmosphere at 673 K for 3 h at a heating rate of 3 K /min. During anodization, the current density significantly increased up to 7.93 mA/cm² for approximately 500 s owing to heat generation, which led to a fast-electrochemical etching reaction of the outermost part of the nanotubes. By controlling the anodization temperature, highly ordered VO₂ nanotubes were grown on the metal substrate without using any binders or adhesives. Furthermore, we demonstrated the hydrogen sorption properties of the anodic VO₂ nanotubes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.380-383
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• 2004

Heavy metal release from wastewater is a serious environmental problem, and therefore, various wastewater treatment techniques have been developed. Among the techniques, sorption technique is most attractive. Considerable researches have been recently focused on finding out inexpensive sorbents, especially from various natural materials. In order to evaluate the applicability of the scoria taken from the Jeju Island, Korea to remove heavy metals (Pb, Cu, Zn, Cd) from aqueous solutions, equilibrium sorption experiments were conducted in this study. In equilibrium tests, powdered activated carbon (PAC), one of the most commonly used sorbents, was also tested to compare the effectiveness of the Jeju scoria with that of PAC. The Jeju scoria had larger adsorption capacity and affinity for metal ions (Pb(II), Cu(II), Zn(II), Cd(II)) than PAC. The sorption parameters of the two sorbents were evaluated by using both the Langmuir and Freundlich isotherms, and the sorption data were better fitted to the Freundlich isotherm. In addition, the sorption behavior of metal ions (Pb(II), Cu(II), Zn(II), Cd(II)) onto the scoria displayed a typical characteristic of the cation sorption. The removal of metal ions decreased at a lower pH condition due to competition with hydrogen ions for the sorption sites of Jeju scoria, while the removal increased at a high pH condition due to hydroxide precipitation.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.383-387
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• 2012

The activation of Mg-10 wt%$Fe_2O_3$ was completed after one hydriding-dehydriding cycle. Activated Mg-10 wt%$Fe_2O_3$ absorbed 5.54 wt% H for 60 min at 593 K under 12 bar $H_2$, and desorbed 1.04 wt% H for 60 min at 593 K under 1.0 bar $H_2$. The effect of the reactive grinding on the hydriding and dehydriding rates of Mg was weak. The reactive grinding of Mg with $Fe_2O_3$ is believed to increase the $H_2$-sorption rates by facilitating nucleation (by creating defects on the surface of the Mg particles and by the additive), by making cracks on the surface of Mg particles and reducing the particle size of Mg and thus by shortening the diffusion distances of hydrogen atoms. The added $Fe_2O_3$ and the $Fe_2O_3$ pulverized during mechanical grinding are considered to help the particles of magnesium become finer. Hydriding-dehydriding cycling is also considered to increase the $H_2$-sorption rates of Mg by creating defects and cracks and by reducing the particle size of Mg.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.49-56
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• 2001

Benzene, one of the aromatic hydrocarbons, can be degraded by physical, chemical and biological processes in aquifers. This study aimed at analyzing separately the three different forms of degradation by performing column tests. Column tests using KCl and benzene as tracers were conducted for four different cases: 1) no hydrogen peroxide and no microorganism, 2) hydrogen peroxide only; 3) microorganism only; 4) hydrogen peroxide and microorganism to investigate the sorption and degradation of benzene. The observed BTCs of KCl and benzene in all cases showed that the arrival times of the peaks of both tracers coincided well but the peak concentration of benzene was much lower than that of KCl. This reveals that a predominant process affecting the transport of benzene in a sandy soil is an irreversible sorption and/or degradation rather than retardation. Decay of benzene through sorption and degradation increased with the addition of hydrogen peroxide and/or microorganism. Dissolved oxygen decreased with the increase of benzene in all cases indicating that degradation of benzene was also influenced by dissolved oxygen. For BTCs with the addition of microorganisms (case 3 and case 4), microorganism showed much lower concentrations compared to the initial levels and an increasing tendency with time although concentrations of benzene returned to zero, indicating a possible retardation of microorganism due to reversible and irreversible sorption to the particle surfaces.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.100-100
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• 1997

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.482-490
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• 2014

Gaseous sulfur compound such as $H_2S$ or COS in coal- or biomass-derived hot syngas can be purified by solid sorbents at high temperatures. In this study, we investigated the physical properties and reactivity of solid regenerable desulfurization sorbents with 37.2, 41.9, and 46.5wt% ZnO to look into the ZnO content effect. The sorbents were produced by spray-drying method to apply to a fluidized-bed process. Sulfidation and regeneration reaction were carried out using a thermogravimetric analyzer. Sorbent prepared with 46.5wt% ZnO had physical properties suitable for a fluidized-bed process applications such as spherical shape, sufficient mechanical strength and density, high porosity and surface area. It showed high sulfur sorption capacity of 10.4wt% (ZnO utilization of 57%) at reaction temperatures of 500 and $650^{\circ}C$ for sulfidation and regeneration, respectively. However, the sulfur sorption capacity and ZnO utilization were significantly reduced and dimple shape appeared when the ZnO content decreased to 37.2 and 41.9wt%. Sulfur sorption capacity and regenerability were improved as reaction temperature increased within the experimental temperatures used in this work. The reaction temperature zones of $1500{\sim}550^{\circ}C$ and $650{\sim}700^{\circ}C$ are recommended for sulfidation and regeneration, respectively, to lead best reaction performances of the ZnO-based spray-dried sorbents developed in this work.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.1
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• pp.7-14
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• 2001

The amount of petroleum consumption has been Increased according to the industrialization and It leads to the increase of the possibility of marine oil pollution. In Korea, some countermeasures including oil skimmer, gelling agent and herding agent of oil have been used for the remediation of the pollution. However, most of them have lets of shortcomings in the application under in-situ condition, because they are sensitive to the situation such as geographical feature, the wind and the tide. In reported literature, the natural powdered oil absorbent which is made of peat moss is an effective mean to clean spilled oil from lake or coast. However, the peat moss is a natural resource which is only Produced from a specific cold weather are like Canada. This indicates that the alternative materials which is readily obtained from everywhere are needed for powdered oil absorbent. Therefore. in the study, same natural materials including pine leaves and straw are tested as the alternative materials for the absorbent. The raw materials were dried and treated by heat at various temperature during several Periods and then. shattered by a grain cracking machine. The oil sorption capacity of the prepared materials was compared according to the methods of heat treatment and their sizes. The proportion of hydrogen cyanide to combustion of the absorbents was measured to confirm their final disposal methods. The biodegradability test of the absorbents was carried our to evaluate possibility of a side pollution in the coast. In was found that the heat treatment of pine leaves enhanced the capacity of oil sorption and decreased the water sorption. The maximum oil sorption was observed for the material treated at 18$0^{\circ}C$for 60 min. The amount of hydrogen cyanide from the combustion were 0.09ml/g, 0.07ml/g for pine leaves and straw respectively meaning that the final disposal by combustion might be feasible. The amount or organic carbon extracted from pine leaves during 7 days was up to 0.015g organic carbon from one gram of pine leaves. but the degradation was as fast as for glucose. It is concluded that the pine leaves can be served as a good raw material for the powdered oil absorbent like peat moss.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.171-179
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• 2005

The influence of the surface roughness and the porosity on the apparent sticking coefficient of the getter was determined quantitatively by Monte Carlo simulation. The sorption characteristics of the getter was investigated by solving numerically the particle balance equation depending on the sticking probability and diffusivity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.745-748
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• 2009

수소는 지구상에 풍부하게 존재하는 원소로 최근 수소경제시대에 대한 기대와 함께 청정 에너지 carrier로 주목받고 있다. 본 연구에서는 고순도 수소 생산을 위해 water gas shift (WGS) 반응과 $CO_2$의 분리를 하나의 unit operation의 형태로 수행하는 신개념의 thermal swing sorption enhanced reaction (TSSER) 공정의 타당성을 테스트하는데 목적을 두고 있다. Le Chatelier 원리를 기본으로 하는 흡착분리 동시 반응 (sorption enhanced reaction, SER)에서는 수소생산 반응의 열역학적 한계를 극복할 수 있고 정반응의 속도를 증대시킬 수 있다. 본 연구에서는 $K_2CO_3$가 첨가된 hydrotalcite에 대한 고온에서의 $CO_2$ 화학흡착 평형 및 거동 데이터를 실험을 통하여 측정하였다. 또한 WGS 상용촉매와 화학 흡착제를 이용하여 흡착분리 동시 반응을 실험과 수치해석 시뮬레이션으로 수행하였고, 연구결과로부터 연료전지에 사용할 수 있는 고순도의 수소 (~10 ppm CO)를 직접 생산할 수 있으며, 동시에 고압상태의 $CO_2$를 고순도로 포집할 수 있음을 확인할 수 있었다. 고압, 고순도의 $CO_2$ 포집은 이후 $CO_2$ 저장에 용이하게 이용되어 온실가스 저감에 기여할 수 있을 것으로 기대된다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.150-150
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• 2005