• 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.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.62-71
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• 2017

This paper presents a low-power voltage converter based on a reconfigurable capacitor array. Its energy recycling capacitor array stores the energy during a charge stage and supplies the voltage during an energy recycle stage even after the power source is disconnected. The converter reconfigures the capacitor array step-wise to boost the lost voltage level during the energy recycle stage. Its energy saving is particularly effective when most of the energy remaining in the charge capacitors is wasted by the leakage current during a longer sleep period. Simulations have been conducted using a voltage source of 500 mV to supply a $V_{DD}$ of around 800 mV to a load circuit consisting of four 32-bit adders in a 65-nm CMOS process. Results demonstrate energy recycling efficiency of 85.86% and overall energy saving of 40.14% compared to a conventional converter, when the load circuit is shortly active followed by a long sleep period.

• 한국조경학회지
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• 제29권5호
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• pp.51-59
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• 2001

This paper presents a design of the Dasan Children\`s Park which is located Shindang- dong, lung-gu, Seoul which has an area of about 3,678$m^2$. Objectives for the design were to make nature-friendly space, learning space, interesting play space, space for every child, adventure play space, traditional play space, sense of place, and recycle space. For the space compositions a children\`s garden, a traditional play space, and a science play space were located around the S shaped main route. Facilities relating nature, science, culture. environment and adventure play were arranged in the 3 main spaces. The Children\`s Garden is a green space for learning and playing with natural elements. It is composed of a ecological learning space, a children\`s story garden, a children\`s song road, an environmental labyrinth, and a pall space leer handicap children. The Science Play Place is a place space for learning scientific theories through plays to which scientific theories were applied. It is composed of a total play structure, a math experience playground, a \"Keojunggi\" play space, a sound reflecting experience space, arid an infant playground. The Traditional Play Madang(space) is a space for traditional plays. It is composed of a traditional play pattern, a sun dial, and a floor fountain. The Recycle Road is a dragon shaped road fort learning about resource recycling and conservation. It is composed of a dragon head, body, tail space and a dragon bead(cint mani).int mani).

• Advances in concrete construction
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• 제10권5호
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• pp.417-429
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• 2020

Waste glass is a global solid waste with huge reserves. The discarded waste glass has caused a series of problems such as resource waste and environmental pollution, so it is urgent to recycle waste glass with high replacement level. Glass powder (GP), as a supplementary cementitious material (SCM), used in cement-based materials has already become one of the important ways to recycle waste glass mainly attributed to its pozzolanic reaction and filling effect, especially to the suppressed ASR expansion. This paper demonstrates an overview of the properties of GP and its effect on the fresh and mechanical properties of cement-based materials. The study found that the influence of GP on the performance of cement-based materials mainly depends on its content, particle size, color and type, curing conditions, and other SCMs. Finally, based on the problems involved in the investigation of concrete containing GP, some corresponding suggestions and efforts are given to further guide the utilization of GP in cement-based materials.

• 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.

• 자원리싸이클링
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• 제14권5호
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• pp.3-12
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• 2005

폐 폴리스티렌 수지의 재활용에 대한 관련 기술의 추이 및 동향을 조사하기 위하여 특허 출원 검색을 시행하였다. 검색 범위는 공개 특허를 대상으로 하였으며 특허 검색 데이터베이스는 미국의 USPTO 및 DELPHION, 일본의 PAJ, 유럽의 EPO, 그리고 한국의 KIPPIS를 선정 조사하였다. 폴리스티렌 수지의 재활용 관련 키워드는 PS, polystyrene, 폴리스티렌, 스티로폼, 그리고 IPC 분류 중 B29B-017, C08J-011를 대상으로 하여 검색하여 총 534건을 선정하였으며 이를 1974년부터 2002년까지 년도 별, 미국, 일본등 주요 국가별, 주요 회사별, 그리고 관련 기술별로 분류하여 분석하였다.

• 자원리싸이클링
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• 제3권1호
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• pp.25-31
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• 1994

AZ91 마그네슘합금 절분 및 스크램외 재활용을 목적으로 절분 및 스크랩을 상온가압하여 빌렛을 얻었다. 이 압출용 벨렛을 압축비율 25:1로 고정하고, 압출온도를 $300~380^{\circ}C$로 변화시켜 가면서 시편을 제조하였으며, 비교재로 마그네슘합금 주조재도 열간압출을 행하였다. 마그네숨합금 절분 및 스크랩을 열간압출함에 따라 매우 미세한 재설정 조직을 얻었으며, 인장강도 및 연산률은 각각 330 MPa, 10%로 주조재를 열간압층한 재료와 거의 비슷한 기계적 특성을 나타내었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.164-168
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• 2005

In this paper a statcom is developed to improve the power quality in a dc traction system. The proposed statcom can be used as both inverter and active filter. As an active filter, it can compensate harmonic distortion and reactive power and as an inverter, it can recycle regenerative energy caused by decelerating trains. The simulation results are carried out by using PSCAD/EMTDC software.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.210-215
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• 1998

In this paper, systemaic approach is studied about assembility and disassemblility of parts of the gear system in order to reduce the assembly cost, and to disassemble products easily which is possible to recycle the parts. That is, an estimation of disassembly and assembly with considering of reliability life. In this study, we use symbolic chart method for an economic model for optimal disassembly and assembly.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.560-565
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• 1986

For the control of chemical process, optimal value of the process should be known at first. And process simulation is the previous step of optimal value calculation. However it is not a simple work to analyze chemical process system. Especially for the large scale chemical process system, many difficulties such as non-linearity and complexity caused by recycle streams should be overcome. In this paper, three strategies of large scale chemical process analysis were explained and discussed with case studies.