• Journal of Hydrogen and New Energy
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• v.30 no.5
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• pp.428-435
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• 2019

A comparative evaluation of engine cleanliness was performed on the transport gasoline blended with bio- alcohols, and this study was considered to achieve the aim of greenhouse gas reduction in Korea. In particular, the fuel blended with bio-ethanol and bio-butanol showed the best engine cleaning performance both on combustion chamber deposits and intake valve deposits. The deposit control gasoline additive was effective to remove intake valve deposits. In contrast, the amount of combustion chamber deposits were tend to increase even though fuels blended with bio-alcohols were used. In overall, fuels blended with bio-alcohols, compared to fossil fuels, still showed outstanding performance in terms of engine cleanliness.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.303-308
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• 1997

전기설비에서 광범위하게 사용하고 있는 유압변압기는 연소성과 환경오염의 문제등으로 인하여 에폭시 수지를 주재로한 진공주형형 몰드변압기로 발전하였다. 따라서 현재는 건축물의 옥내에는 광범위하게 사용되고 있다. 본 논문에서는 에폭시 수지를 사용한 진공주형형 몰드변압기를 시료로 사용하여 전기실과 유사한 환경에서 연소시험에 의한 난연성과 자기소화성을 확인하여 몰드변압기로 인한 소화설비의 불필요성을 입증하였고, 청정소화 약제의 하나인 NAF S-III소화제로서 소화실험을 시행하여 그 소화시간을 측정하고 연소 시험의 결과와 비교 평가하였다. (중략)

• Clean Technology
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• v.12 no.2
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• pp.78-86
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• 2006

Computational analyses are conducted on the combustion characteristics of the coal- and the biomass-derived synthetic gases with low-Btu heating value in gas engine. Using thermochemical analyses on the synthetic gases, combustion pressure, temperature, exhaust gas composition, NO emission and engine power are predicted and the predicted results are compared with small-scale pilot engine test results. In order to investigate the unsteady combustion phenomena in gas engine combustion chamber, CFD analyses are carried out on the coal and the biomass synthetic gases and their computed results are compared to provide the guidelines for the design modification and the tuning of the gas engine burning the synthetic gases as alternative fuels.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.430-439
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• 1990

Steady state turbulent airflow and unsteady characteristics of generation, transportation, and recovery behavior of contaminate particles in the simplified 2 dimensional Vertical Laminar Flow (VLF) type clean room was numerically simulated using the low Reynolds number k-over bar.epsilon- turbulent model. Characteristics of airflow in VLF type clean room are greatly affected by the recirculation zone around working surface. The recirculation zone must be considered at the time of clean room design because the recirculation zone whose area increases with increment of inlet velocity exerts bad influence upon the performance of clean room in terms of particle contamination. The location of maximum particle concentration changes from the location of particle source to the recirculation zone, while averaged particle concentration is reduced exponentially with time. Recovery time of clean room with spontaneous particle generation source is inversely proportional to inlet velocity. We introduce nondimensionalized recovery time through the dimensional analysis, which can indicates the general performance of clean room with design structure change. It was identified that .tau. is independent of inlet velocity and background concentration. Therefore .tau. can be the simple factor to compare the different structure of clean room in terms of dynamic response to contamination and becomes larger with better structure of clean room.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.926-933
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• 1988

A Numerical method has been introduced to handle a pressure-based boundary condition of the incompressible viscous flow field. This method, based on SIMPLER algorithm, has been applied to analyze the flow characteristics within a two-dimensional duct of two-exit, as an example. From this, it is possible to determine the ratio of flow rate through two exits imposed on different static pressure. In order to check the validity of the present method, calculated velocity at the boundary imposed on pressure condition by the use of present method has been transferred to the velocity boundary condition of the conventional numerical method workable only with the velocity-based boundary condition. It is found that the calculated boundary pressure from conventional method are almost identical to those endowed originally. Present method, therefore will be widely applicable to the practical situations specified by the pressure-based boundary condition rather than the velocity one.

• Elastomers and Composites
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• v.37 no.2
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• pp.107-114
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• 2002

This paper discusses the accelerated heat aging tests were carried out to predict the useful life of EPDM isolating rubber components of ventilation fan motor for clean room. 20% compression set results changes as the threshold are used for assessment of the useful life and the time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. The useful life at variable temperatures and activation energy are obtained from the Arrhenius relationship. An accelerated test program to assess useful life can be represented an appreciable investment in time was designed. We also considered the effect of antioxidant agents.

• Particle and aerosol research
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• v.16 no.3
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• pp.65-72
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• 2020

In this study, the indoor fine dust concentration in an office of the Korea Knowledge Industry Center was measured for about 80 hours when the concentration of atmospheric PM_2.5 was very high. The effect of the operation of the air cleaner and the forced ventilation system on the indoor PM_2.5 was investigated, and the particle size distribution of the indoor and outdoor particles was analyzed. When forced ventilator and air purifiers were partially used, the indoor PM_2.5 concentrations were maintained between 27.7 ㎍/㎥ and 32.9 ㎍/㎥ when the atmospheric PM_2.5 was 127.7 ㎍/㎥ to 141.6 ㎍/㎥ during working hours. It is more effective to operate the air purifier without operating the forced ventilation system when the concentration of the PM_2.5 is high since the PM_2.5 penetrating the installed filter is continuously introduced indoor from the outside.

• Clean Technology
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• v.28 no.3
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• pp.203-209
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• 2022

An environmental evaluation was conducted by employing LCA methodology for a mechanical seal manufacturing process that uses recycled silicon recovered from end-of-cycle PV modules. The recycled silicon was purified and reacted with carbon to synthesize β-SiC particles. Then the particles underwent compression molding, calcination and heat treatment to produce a product. Field data were collected and the potential environmental impacts of each stage were calculated using the LCI DB of the Ministry of Environment. The assessment was based on 6 categories, which were abiotic resource depletion, acidification, eutrophication, global warming, ozone depletion and photochemical oxidant creation. The environmental impacts by category were 45 kg CO₂ for global warming and 2.23 kg C₂H₄ for photochemical oxide creation, and the overall environmental impact by photochemical oxide creation, resource depletion and global warming had a high contribution of 98.7% based on weighted analysis. The wet process of fine grinding and mixing the raw silicon and carbon, and SiC granulation were major factors that caused the environmental impacts. These impacts need to be reduced by converting to a dry process and using a system to recover and reuse the solvent emitted to the atmosphere. It was analyzed that the environmental impacts of resource depletion and global warming decreased by 53.9% and 60.7%, respectively, by recycling silicon from end-of-cycle PV modules. Weighted analysis showed that the overall environmental impact decreased by 27%, and the LCA analysis confirmed that recycling waste modules could be a major means of resource saving and realizing carbon neutrality.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1059_1060
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• 2009

신재생에너지 분야 중 가장 활발하게 개발 및 보급되는 태양광발전은 유한 에너지인 석유, 석탄, 천연 가스에 비해 비고갈성의 청정 에너지원으로 각광 받고있다. 화석연료를 사용하면서 발생 할 수 있는 지구환경 문제에 대처 할 수 있고, 수력이나 원자력발전과 달리 비교적 입지에 영향이 적을 뿐만 아니라 전력 수요지 근처에 설치하여 직접 전기에너지를 공급할 수 있는 이점이 있다. 반면에 그늘이나 구름 등 주변 환경에 영향을 많이 받고 넓은 부지와 높은 초기 투자비를 필요로 한다. 특히 태양광발전은 직류전력을 발생하므로 이를 교류로 변환시키는 태양광발전용 전력변환장치(Power Conditioning System; 이하 "PCS")가 필요하다. 본 고에서는 중소기업지원과제로 개발되어 한전 전력연구원의 태양광발전 실증시험장에서 실 계통 연계 운전을 통하여 취득한 50kW급 계통연계형 multi- string PCS의 초기 운전특성에 대하여 소개하고자 한다.

• Tribology and Lubricants
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• v.7 no.2
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• pp.13-21
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• 1991

선박은 사람이나 화물을 수상(水上) 운송수단의 목적으로 오랜 옛날부터 사용하여 왔으며, 금세기에 이르러서는 오랜 옛날부터 사용하여 왔으며, 금세기에 이르러서는 인류문화의 급속한 발전에 따라 주변생활이 가속화(Speed화), 합리화되어 문명의 혜택을 보다 많이 누리게 된 반면에, 국제간에 파생되는 여러가지 교환현상을 바탕으로 지구는 하나의 촌(村)으로 되어 유통경제를 지배하고 이용하는 운송수단으로 발전되어 왔다. 물질문명이 급속히 발전하는 작금, 선용추진 주 기관의 동향을 살펴보면, 1981년 세계에서 건조한 2000톤급 이상의 선박은 940여척으로 이중 13척이 증기 Turbine. 추진(推進), 나머지는 미끄럼 저속 디이젤 또는 중고속 디이젤 추진으로 되어있다. 이와 병행하여 선박에 쓰여지고 있는 각종 윤활제는 주기관으로서 디이젤 engine, Trubine engine, 가솔린 engine, 석유, engine, 선외기, 왕복동 증기기관, Journal계열로서 역전기, 추력베어링, 중간 베어링, 프로펠러베어링, 일반상선으 보조기계로서 발전기, 공기압축기, Boiler, 각종 Pump, 각종 Motor, 냉동기, 조타장치, Side Thrust, 갑판기계, 환기용 송풍기 및 통풍통, Oil 청정기, 수밀로(水蜜爐), 소화설비, 주기 개방용 천정 크레인, elevator, 어선으로서의 주 기관, 보조기기 등에 쓰여지고 있으며 이밖에 수중날개선 등에도 적용되는 등 실로 다양다종한 윤활제가 요구되고 있음에, 본 논고에서는 제목 건을 중심으로 한 선박과 윤활의 중요 Point만을 간추려 기술하고져 한다.