• 한국건축시공학회지
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• 제3권1호
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• pp.123-129
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• 2003

The production accounts of domestic by-product is increased after 1990's. It is worried about the life reduction of dump land, as dump land's capacity have reached to limitation and the amount of construction industrial wastes is going higher. Recently, recycling aggregates could be gained from the reconstruction works using recycle process, and the study research of recycle concretes developed concrete application methods. It could put some outcome of studies to practical use for concrete products. The methods of crushing waste concrete are going diverse. In this study. the fundamental experiments and recycling application is investigated and analyzed with use of recycling aggregate which made of mechanical crush and underwater electrical impact crush, and the difference between underwater electrical impact crush, mechanical crush and natural aggregates is studied.

• 대한토목학회논문집
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• 제13권1호
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• pp.221-232
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• 1993

본 연구는 도시폐기물을 매립지에서 발생하는 침출오수를 실험실에서 유기질 도시폐기물을 충진한 모형매립반응조를 이용하여 각기 다른 체류시간에 따른 침출오수 순환방식과 비순환방식으로 운영했을 때의 안정화에 소요되는 기간을 비교 분석하였다. 그 결과 pH 조정(중성)에 의한 침출오수 재순환은 매립지내의 혐기성균을 급속하게 증대시켜 유기물의 생물학적 분해를 가속화시키고 안정화기간을 단축시켰다. 침출오수의 BOD와 COD의 경우 초기에는 COD=BOD 였으나, 매립기간이 경과함에 따라 COD>BOD, $COD{\gg}BOD$ 의 추세를 보였다. 가스발생량은 침출오수 비순환반응조보다 재순환반응조에서 더욱 많이 발생하였고 체류시간이 짧을수록 가스발생량이 증가하였다.

• 한국연소학회지
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• 제18권4호
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• pp.1-11
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• 2013

The oxy-fuel combustion is $CO_2$ capture technology that uses mixture of pure $O_2$ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet $CO_2$ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of $CO_2$ purity of CPU inlet.

• Environmental Engineering Research
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• 제25권3호
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• pp.400-408
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• 2020

Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

• 한국건설관리학회논문집
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• 제9권1호
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• pp.77-86
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• 2008

최근 국내외적으로 친환경에 대한 국제적인 관심이 증가됨에 따라, 건설 산업 측면에서도 친환경적인 생산시스템 구축을 위한 노력이 요구되고 있다. 이에 부응하기 인해 건설폐기물 재활용과 관련하여 다양한 실무와 연구가 진행되고 있지만, 현장조사결과 '건설현장'과 '폐기물 처리업체'에서 수행하고 있는 폐기물 처리과정 및 처리방안이 상호 효과적으로 지원하고 있지 못하여 폐기물 재활용 저해요소로서 작용하고있는 실정이다. 따라서 본 연구에서는 건설폐기물의 재활용을 활성화시키는 방안으로써, '건설현장'과 '폐기물 처리업체'의 건설폐기물 처리과정에서 폐기물 재활용을 저해하는 요인을 도출하고, 이를 기반으로 개선방향을 제시하고자 한다. 이러한 연구목표를 달성하기 위해, 먼저 광범위한 문헌조사를 통해 대표적인 건설폐기물 종류(폐 콘크리트, 폐 아스팔트, 폐 토사, 폐 벽돌, 폐 합성수지, 폐 목재)를 선정하였고, '건설현장'과 '폐기물 처리 업체'를 대상으로 전문가 면담을 실시하여, 이들 개별 폐기물의 처리과정 조사를 통해서 폐기물 재활용 저해요인을 조사하였다. 또한, 전문가 면담 결과로 파악된 폐기물 재활용 저해요인을 설문조사를 통해 중요도 및 우선순위를 파악하였다. 이를 기반으로 현행 건설폐기물 처리 프로세스를 개선함으로써, 재활용 효율화 방안을 제시하였다.

• 상하수도학회지
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• 제26권1호
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• pp.107-113
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• 2012

Pollutants in aquaculture system effluent mostly originated from solid wastes including uneaten feed and excreta of cultured species. In this research, DAF(Dissolved Air Flotation) unit is suggested as an integrated solid control unit especially as a form of IIBG(Inline Injection Bubble Generation) process in aquaculture system. Solid removal performance of DAF unit was examined under various operation and salinity conditions with turbidity and suspended solid. Solid waste removal efficiencies were found to be affected by operation conditions including saturator pressure, recycle ratio, coagulant concentration. Solid removal efficiency was higher under higher saturator pressure and recycle ratio under which condition larger number of bubbles is generated. Coagulant is thought to have important role in creating bubble-particle aggregate by showing better removal efficiency with higher concentration. However higher saline water showed less effectiveness in removing solids by DAF(IIBG). Application of DAF(IIBG) process also showed additional effect in phosphate removal and DO(Dissolved Oxygen) supply. Phosphate existed in polluted water was removed up to 46% after treatment, which is thought to attribute to aluminium phosphate precipitation. And DO concentration was found to increase over 50% of initial saturation concentration after the injection of micro-bubbles. Through experiments on solid removal from aquaculture effluent, DAF(IIBG) process is estimated to be effective solid control method. This property can help aquaculture system being installed and operated simply and effectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1322-1324
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• 2002

For developing a 100 kW MCFC power generation system, Several design parameters for a fuel cell stack and system analysis results by Cycle Tempo, a processing computer soft ware, were described. Approximately 170 cells are required to generate 100 kW at a current density of 125 mA/$cm^2$ with 6000 $cm^2$ cells. An overall heat balance was calculated to predict exit temperature. The 100 kW power is expected only under pressurized operation condition at 3 atm. Recycle of cathode gas by more than 50% is recommended to run the stack at 125 mA/$cm^2$ and 3 atm. Manifolds should be designed based on gas flow rates for the suggested operating condition. The fuel cell power generation system was designed conceptually with several choices of utilization of anode exhaust gas. Also system efficiency was calculated at various type of system and operation conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1300-1302
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• 2001

For developing a 100 kW MCFC power generation system. Several design parameters for a fuel cell stack and system analysis results by Cycle Tempo, a processing computer soft ware, were described. Approximately 170 cells are required to generate 100 kW at a current density of $125mA/cm^2$ with $6000cm^2$ cells. An overall heat balance was calculated to predict exit temperature. The 100 kW power is expected only under pressurized operation condition at 3 atm. Recycle of cathode gas by more than 50% is recommended to run the stack at $125mA/cm^2$ and 3 atm. Manifolds should be designed based on gas flow rates for the suggested operating condition. The fuel cell power generation system was designed conceptually with several choices of utilization of anode exhaust gas. Also system efficiency was calculated at various type of system and operation conditions.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.23-27
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• 2016

The technologies using magnetic force control have been investigated toward application in various fields. Some of them have been put into practical use as the results of technological development. This paper introduces our technical development in the field of water processing, scale removal, magnetic drug delivery system, decontamination of radioactive substances and resources recycling.

• 기술사
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• 제45권1호
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• pp.42-44
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• 2012

Recently human beings are experiencing fatal matters of environmental harm from enormous demolished concrete, even though waste concrete can get much more market value if recycled. The problem is that demolished concrete can not find the place where it can be used more economically and efficiently, but eventually can be spent worthlessly for landfill or road basement. Up to now, we can barely find the right place matching for structural performance in construction site with recycled concrete, even more, can not find another place to recycle this tremendous waste concrete. in addition it needs recycling information system between demanders and suppliers managed by government and other.