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A Study on the Estimation of Optimal Unit Content of Binder for the Soil Stabilizer Using the Recycled Resource in DMM (심층혼합공법에서 순환자원을 활용한 지반안정재의 최적 단위결합재량 산정에 관한 연구)

  • Seo, Se-Gwan;Lee, Khang-Soo;Kim, You-Seong;Cho, Dae-sung
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.2
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    • pp.37-44
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    • 2019
  • The compressive strength of the soil stabilizer in the deep mixing method (DMM) depends on kinds of soil, particle size distribution, and water content. Because of this, Laboratory test has to perform to estimate the unit weight of binder to confirm the satisfaction of the design strength. In this study, uniaxial compression strength was measured by mixing the soil stabilizers developed in the previous study with clay in Busan, Yeosu, and Incheon area. And the strength enhancement effect was evaluated comparing with blast furnace slag cement (BFSC). Also, the relationship between the unit content of binder and uniaxial compressive strength was investigated in order to easily calculate the unit weight of binder required to ensure the stability of the ground at the field. As the results of the analysis, the relationship between the unit content of binder and the uniaxial compressive strength are ${\gamma}_B=(108.93+0.0284q_u){\pm}35$ when W/B is 70%, and ${\gamma}_B=(122.93+0.0270q_u){\pm}40$ when W/B is 80%.

Changes of Adsorption Capacity and Structural Properties during in situ Regeneration of Activated Carbon Bed Using Ozonated Water (오존수 산화를 이용한 활성탄 흡착탑의 현장 재생 시 흡착용량 및 구조특성의 변화)

  • Lee, Jinjoo;Lee, Kisay
    • Applied Chemistry for Engineering
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    • v.31 no.3
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    • pp.341-345
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    • 2020
  • An in situ regeneration of activated carbon bed using an ozonated water was studied in order for avoiding the carbon loss, contaminant emission and time consuming for discharge-regeneration-repacking in a conventional thermal regeneration process. Using phenol and polyethylene glycol (PEG) as adsorbates, the adsorption breakthrough and in situ regeneration with the ozonated water were repeated. These organics were supposed to degrade by the oxidation reaction of ozone, regenerating the bed for reuse. As the number of regeneration increased, the adsorption capacity for phenol was reduced, but the change was stabilized showing no further reduction after reaching a certain degree of decrement. The reduction of adsorption capacity was due to the increase of pore size resulting in the decrease of specific surface area during ozonation. The adsorption capacity of phenol decreased after the ozonated regeneration because the in-pore adsorption was prevalent for small molecules like phenol. However, PEG did not show such decrease and the adsorption capacity was constantly maintained after several cycles of the ozonated regeneration probably because the external surface adsorption was the major mechanism for large molecules like PEG. Since the reduction in the pore size and specific surface area for small molecules were proportional to the duration of contact time with the ozonated water, careful considerations of the solute size to be removed and controlling the contact time were necessary to enhance the performance of the ozonated in situ regeneration of activated carbon bed.

Research Trends of Polybenzimidazole-based Membranes for Hydrogen Purification Applications (수소 분리 응용을 위한 폴리벤즈이미다졸 기반 분리막의 연구 동향)

  • Kim, Ji Hyeon;Kim, Kihyun;Nam, Sang Yong
    • Applied Chemistry for Engineering
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    • v.31 no.5
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    • pp.453-466
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    • 2020
  • As the demand for eco-friendly energy increases to overcome the energy shortage and environmental pollution crisis, hydrogen economy has been proposed as a potential solution. Accordingly, an economical and efficient hydrogen production is considered to be an essential industrial process. Research on applying hydrogen separation membranes for H2/CO2 separation to the production of highly concentrated hydrogen by purifying H2 and capturing CO2 simultaneously from synthetic gas produced by gasification is in progress nowadays. In high temperature environments, the membrane separation process using glassy polymeric membrane with H2 selectivity has the potential for CO2 capture performance, and is an energy and cost effective system since polybenzimicazole (PBI)-based separators show excellent chemical and mechanical stability under high-temperature operation conditions. Thus, the development of high-performance PBI hydrogen separators has been rapidly progressing in recent years. This overview focuses on the recent developments of PBI-based membranes including structure modified, cross-linked, blended and carbonized membranes for applications to the industrial hydrogen separation process.

Effects of Oxidation Process on Thermal Properties of Petroleum-based Isotropic Pitch (산화 공정이 석유계 등방성 피치의 열거동 특성에 미치는 영향)

  • Lee, Namji;Seo, Sang Wan;Kwak, Cheol Hwan;Kim, Min Il;Im, Ji Sun
    • Applied Chemistry for Engineering
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    • v.31 no.1
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    • pp.36-42
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    • 2020
  • In order to investigate the effect of the oxidation process on thermal properties of the pitch, the oxidized pitch was prepared by changing the oxidation temperature. Thermal properties of the pitch were analyzed using thermogravimetric analysis (TGA), and it divided into three sections as A (25~100 ℃), B (250~550 ℃) and C (550~800 ℃) by derivative thermogravimetry (DTG) graph behavior. In the A section, the was reduced because the moisture contained in the pitch was removed. In the B section, as the oxidation temperature increased, the thermal stability of the pitch is improved. Because the degree of aromaticity and molecular weight of the pitch increased with increasing oxidation temperature. In contrast, the results of the C section were shown opposite of B section. Because the introduced C-OH, C-O-C, and C=O bonds were decomposed, and the resulting oxygen compounds induced the combustion reaction of the pitch.

A Study on the Field Application of Ground Stabilizer using Circulating Resource for Improvement of Soft Ground in Saemangeum Area (새만금 지역의 연약지반 개량을 위한 순환자원 활용 지반안정재의 현장적용에 관한 연구)

  • Seo, Se-Gwan;Kim, You-Seong;Cho, Dae-sung
    • Journal of the Korean Geosynthetics Society
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    • v.19 no.1
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    • pp.103-110
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    • 2020
  • The DMM (Deep mixing method) is a construction method in which an improved pile is installed in the soft ground by excavation ground using an auger and then mixing ground stabilizer with soil. Improved pile installed in the soft ground by the DMM may have different compressive strength depending on the properties and characteristics of the soil. In the previous study, laboratory tests were performed on the ground stabilizer for the DMM developed by using the ash of the circulating fluidized bed boiler as a stimulator for alkali activation of the blast furnace slag. And the test results were analyzed to derive the correlation between the unit weight of binder (γB) and the uniaxial compressive strength (qu). In this study, comparative reviews were conducted on the correlations derived from the same laboratory tests on soil material collected from the Saemangeum area and the stability of the site was evaluated by analyzing the test results performed at the site. As a result, the clay collected from the Saemangeum area satisfies the correlation between the unit weight of binder (γB) and the uniaxial compressive strength (qu) derived from the previous study. And the result of the test at the field showed a higher uniaxial compressive strength than the standard strength at the field, indicating excellent stability.

The Feasibility Study for Utilization of Blended Cement as a Activator of Bottom Ash from Circulating Fluidized Bed Combuster Boiler (순환유동층 보일러 바텀애시의 혼합시멘트 자극제 활용을 위한 타당성 연구)

  • Park, JongTak;Jung, Gwon Soo;Kang, Chang Ho;Oh, Hongseob
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.3
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    • pp.255-262
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    • 2020
  • Blended cement with fly ash and bottom ash from Circulating Fluidized Bed Combustor boiler(CFBC) burned at a low temperature, can be high heat of hydration and abnormal setting caused by higher volumn contents of Fe2O3, free-CaO, SO3. In this study, the ground CFBC bottom ash powder mixed with blast furnace slag was used as substitute activator of gypsum and recycled iron slag was produced from mix and pulverized by ball mill to increase the recycling rate. The effect on compressive strength of cements with the mixture of original and hydrated bottom ash mixtures with BFS with small water, respectively, was analyzed, and it was found that the hydrated bottom ash activator was more effective in initial strength development. To improve the initial strength of blended cement, an activator mixed with a blast furnace slag and bottom ash mixing ratio of 5:95 and 10:90, respectively, the slag cement by about 6%, and it was analyzed to develop an initial strength similar to gypsum as a conventional activator.

Absorption characteristic of carbon dioxide in Ionic Liquids based sulfite anion in the pre-combustion condition (연소 전 조건에서 음이온이 Sulfite계인 이온성 액체의 CO2 흡수 특성)

  • Baek, Geun Ho;Jang, Hyun Tae;Cha, Wang Seog
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.3
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    • pp.763-769
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    • 2021
  • In this study, ionic liquids were synthesized to remove carbon dioxide (CO2) on a laboratory scale. The vapor-liquid absorption equilibrium device (VLE) was used to investigate the carbon dioxide absorption capacity. In the regeneration study, the absorption capacity after regeneration was reduced by approximately 7% for all ionic liquids, in which the anion was sulfite-based, showing excellent regeneration. Ethyl sulfite showed the highest absorption capacity of CO2 among the ionic liquids based on the sulfite anion. In particular, the absorption capacity of [beim] ethyl sulfite was 1.1 mol CO2 / mol IL at an absorption equilibrium pressure of 22 bar. In the regeneration study, the absorption capacity after regeneration was reduced by approximately 7% for all ionic liquids, in which the anion was sulfite-based, from which regeneration is outstanding. After the absorption experiment, the viscosity of the sample tended to decrease by approximately 8% compared to that before the absorption experiment. On the other hand, the absorbent was synthesized in the first step. Moreover, the raw material used is also inexpensive and has excellent reproducibility and highly stable absorbent capacity.

Effect of SO2 on NOx Removal Performance in Low Temperature Region over V2O5-Sb2O3/TiO2 SCR Catalyst Washcoated on the Metal Foam (저온영역에서 메탈폼에 코팅된 V2O5-Sb2O3/TiO2 SCR 촉매의 NOx 저감성능에 미치는 SO2 영향에 관한 연구)

  • Na, Woo-Jin;Park, Young-Jin;Bang, Hyun-Seok;Bang, Jong-Seong;Park, Hea-Kyung
    • Clean Technology
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    • v.22 no.2
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    • pp.132-138
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    • 2016
  • The emission of SO2 is inevitable in case of combustion of most fossil fuels except LNG in commercial power plant which has a bad effect on the durability of SCR catalyst. To develop a low temperature SCR catalyst which has a high NOx removal performance and excellent durability to SO2, V2O5/TiO2 catalysts were prepared by coating on the metal foam substrate with the impregnation amount of Sb2O3 as promotor. This study has evaluated the NOx removal performance and the durability to SO2 on a laboratory scale atmospheric reactor and analyzed the properties of the prepared catalysts by means of porosimeter, BET, SEM (scanning electron microscope), EDX (energy dispersive x-ray spectrometer), XPS (X-ray photoelectron spectroscopy). It was found that the surface area of catalyst increased with the impregnation amount of Sb2O3 and the NOx removal performance showed the highest value at the 2 wt% impregnation of Sb2O3. This results was considered to be due to the optimum active site on the catalyst surface. And also, Sb2O3 impregnated catalysts presented that NOx removal performance was maintained despite the exposure to SO2 for 5 hours. Therefore it was confirmed that metal foam SCR catalyst for low temperature could be manufactured with the optimum control of Sb2O3 impregnation according to the SO2 presence or not.