• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.65-68
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• 2009

Recycled aggregate by the recycling construction waste has a lot of advantage such as the developing the alternative resource and protecting of environment. However, recycled aggregate is used as the low quality grade, because the technic to remove old mortar from aggregate is low level. To use the recycled aggregate as high quality grade, it is important to develop the technic to produce the high quality recycled aggregate. To manufacture the high quality recycled aggregate, old mortar attached on the aggregates should remove efficiently. Therefore, in this study, we suggested the optimum condition to remove old mortar effectively using sulfuric acid and low speed wet rotary mill for high quality recycled fine aggregate. The results shows that the recycled aggregate satisfy on the standards of KS F 2573 in density, absorption and solid volume when, adequate condition of sulfuric mole ratio and aggregate ratio are make.

• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.484-492
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• 2015

As our government is actively introducing the RPS (Renewable Portfolio Standards) as a national renewable energy obligation policy, power producers are using the various renewable energy to meet the RPS supply quota since 2012. Recently, it is appling to use power bio-fuel oil in bio-fuel oil demonstration project with power companies. In general, power bio-fuel oils are composed of mixture products of vegetable oil, animal fat, fatty acid ester and waste oil. It is already developing for a power plant as a renewable energy abroad. In Korea, it is studying a 100% combustion and blended combustion of heavy fuel oil and bio-fuel oil. In this study, we investigated fuel characteristics of mixed power bio-fuel oil and its emission performance. Especially, it was reduced emissions of bio-oil in industrial boilers due to bio-fuel properties as compare with fuel oil.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.498-505
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• 1999

Trivalent actinide-lanthanide group separation is difficult to perform on an industrial scale, because of the many drawbacks of the available chemical process. In this paper, picolinamide(C$_{8}$H$_{17}$) is synthesized and characterized, and extraction yields of Am-241, Eu-152 and Nd are determined in batch extraction experiments. In particular, the influence of the solvent is described. The extraction yields of Am-241, Eu-152 and Nd depended on the LiNO$_3$ concentration, the picolinamide(C$_{8}$H$_{17}$) concentration and the acidity. A favorable picolinamide(C$_{8}$H$_{17}$) concentration was found to be about 2M. The appropriate nitric acid concentration and LiNO$_3$ concentration were confirmed to be about 0.125M and 3M, respectively. The separation factor of Am and Eu was about 9.9 at optimum conditions. The picolinamide(C$_{8}$H$_{17}$) is a very promising extractant for the actinide(III)-lanthanides(III) separation.aration.aration.

• 상하수도학회지
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• 제11권4호
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• pp.43-53
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• 1997

In this research, the synthetic livestock wastewater was prepared to study the characteristics of organic matter removal, the change of VFA production, and the amount of gas production with respect to the change of ammonium nitrogen concentration in the waste using anaerobic fixed bed process, which is an anaerobic biofilm process. The HRT and operation temperature were 1 day and $35{\pm}1^{\circ}C$, respectively. Also, the characteristics of organic matter removal and the inhibitory effect on microorganism in the anaerobic process were studied on the organic loading and ammonium nitrogen concentration. The results obtained were as follows: For COD loading of $10kg/m^3$-day and five levels of ammonium nitrogen concentration ranging from 1,000 to 5,000 mg/L, organic removal efficiencies were about 81, 74, 67, 58, and 51%, and gas productions were 3,860, 3,520, 3,240, 3,020, and 2,790 ml/l-day, respectively. Average methane contents in the gas produced on COD loading of $10kg/m^3$-day was about 76%. Throughout the whole period of experiment, remaining VFA (as COD base) in the effluent was over 90% of remaining COD. This result indicated the inhibitory effect of high concentration of ammonium nitrogen through the facts that accumulated VFA was almost COD and organic removal efficiency decreased also with the increase of ammonium nitrogen. Especially, that implys which high concentration of ammonium nitrogen not only inhibits methane forming bacteria, but also acid forming bacteria.

• 한국버섯학회지
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• 제18권2호
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• pp.141-144
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• 2020

BW를 이용하여 느타리를 재배함에 있어 면실박을 대체할 수 있는 재료를 찾기 위해 시험이 진행되었다. 일반성분 분석에서 BW가 면실박에 비해 단백질 함량은 다소 떨어졌으나 자실체의 생육특성에서 BW 혼합 시 대조구와 수량 등의 생육특성이 유사함을 확인할 수 있었고, 자실체의 구성아미노산 조성 확인결과 처리구 간 아미노산의 함량은 큰 차이를 나타나지 않았다. 따라서 BW가 느타리 배지제작에 있어 면실박을 대체하여 사용될 수 있을 것으로 판단된다.

• 자원리싸이클링
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• 제6권3호
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• pp.22-27
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• 1997

방사성 금속폐기물을 재활용하므로써 방사성 폐기물의 처분부피를 감축할 수 있을 뿐만 아니라, 자원활용의 극대화를 꾀할 수 있으며, 또한 방사성 폐기물의 감량으로 환경에 미치는 위해도를 최소화시킬 수 있다. 방사성 금속폐기물의 재활용은 여러 단계를 복잡한 공정을 거치면서 이루어지지만, 오염 방사능 물질을 제거하는 표면제염 공정이 핵심이며, 그 오염 특성 및 폐기물에 따라 물리적, 화학적 그리고 전기화학적 방법이 활용된다. 본 연구에서는 이러한 관점에서 표면제염기술의 특성을 고찰하였으며, 실제 방사성 금속폐기물을 이용해 SC 화학제염법 및 전해제염법으로 시험한 결과, 거의 자연 방사능 수준까지 제염시킬 수 있었다.

• Advances in Energy Research
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• 제7권2호
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• pp.147-166
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• 2020

Industrial cooling towers are often ageing infrastructure that is expensive to maintain and operate. A novel approach is introduced in which a heat pump circuit is incorporated to reduce the load upon the towers by extracting low-grade energy from the stream sent to the towers and repurposing in on-site processing operations. To demonstrate the concept, a model was constructed, which uses industrial data on cooling towers linked to a smelter's sulphuric acid plant, to allow direct economic and environmental impact comparison between different heat recovery and repurposing scenarios. The model's results showed that implementing a heat pump system would significantly decrease annual operating costs and achieve a payback period of 3 years. In addition, overall CO₂ emissions could be reduced by 42% (430,000 kg/year) and a 5% heat load reduction on the cooling towers achieved. The concept is significant as the outcomes introduce a new way for energy intensive industrial sectors, such as mineral processing, to reduce energy consumption and improve long-term sustainable performance.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.582-588
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• 1995

The preconcentration and determination of trace Cd(Ⅱ), Cu(Ⅱ), Pb(Ⅱ), Mn(Ⅱ) and Zn(Ⅱ) in water samples were studied by the precipitate flotation using La(OH)3 as a coprecipitant. The analytes were quantitatively coprecipitated by adding 3.0 mL of 0.1 M La(Ⅲ) solution in a 1,000 mL water sample and adjusting the pH to 9.5 with NaOH solution. After the addition of the 1:8 mixed surfactant solution of each 0.1% sodium oleate and sodium lauryl sulfate, the solution was stirred with a magnetic stirrer for 10 minutes. The precipitates were floated to the surface by bubbling with nitrogen gas and collected in a small sampling bottle. The precipitates were dissolved in nitric acid and then the solutions were diluted to 25.00 mL with a deionized water. The analytes were determined by flame atomic absorption spectrometry. This procedure was applied to the waste water analysis. This technique was simple, convenient and especially rapid for the analysis of a large volume of sample. And also, from the recoveries of better than 92% which were obtained from real samples, this method could be judged to be applicable to the preconcentration and quantitative determination of trace elements in water samples.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3798-3807
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• 2021

Tritium extraction from radioactively contaminated cement mortar samples was performed using heating and liquid scintillation counting methods. Tritiated water molecules (HTO) can be present in contaminated water along with water molecules (H₂O). Water is one of the primary constituents of cement mortar dough. Therefore, if tritium is present in cement mortar, the buildings and structures using this cement mortar would be contaminated by tritium. The radioactivity level of the materials in the environment exposed to tritium contamination should be determined for their disposal in accordance with the criteria of low-level radioactive waste disposal facility. For our experiments, the cement mortar samples were heated at different temperature conditions using a high-temperature combustion furnace, and the extracted tritium was collected into a 0.1 M nitric acid solution, which was then mixed with a liquid scintillator to be analyzed in a liquid scintillation counter (LSC). The tritium extraction rate from the cement mortar sample was calculated to be 90.91% and 98.54% corresponding to 9 h of heating at temperatures of 200 ℃ and 400 ℃, respectively. The tritium extraction rate was close to 100% at 400 ℃, although the bulk of cement mortar sample was contaminated by tritium.

• Environmental Engineering Research
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• 제24권2호
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• pp.324-330
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• 2019

To recycle raw fly ash (RFA), a waste from thermal power plants, it was used to prepare solid catalysts which have many advantages compared with homogenous catalysts. When biodiesel was produced from soybean oil using RFA, only 1.2% of biodiesel conversion was obtained. A metal hydroxide, NaOH, KOH or $Ca(OH)_2$, was mixed with the acid-treated fly ash (ATFA), and the mixture was calcined at $700^{\circ}C$ for 3 h to prepare the solid catalyst. The solid catalyst prepared by mixing ATFA with NaOH, designated as SC-Na, showed a better performance than those prepared by mixing ATFA with KOH or $Ca(OH)_2$, respectively. The optimal mass ratio of ATFA with NaOH was 1:3, at which the proportion of $Na_2O$ increased to 60.2% in SC-Na, and 97.8% of biodiesel conversion was achieved under optimal reaction conditions (2 w% SC-Na relative to oil and 5 mL-methanol/g-oil at $50^{\circ}C$ for 4 h). Finally, a batch operation was repeatedly carried out to test the feasibility of reusing the solid catalyst, and more than 96% biodiesel conversion was stably achieved for the third round of operations. This study shows that RFA was successfully recycled to solid catalysts through a simple preparation method, and the solid catalyst was reused for the production of biodiesel with high conversion.