• 한국추진공학회지
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• 제22권5호
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• pp.40-48
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• 2018

본 논문은 시뮬레이션 기반으로 메타 모델을 이용하여 LEEFI형 착화장치의 설계 신뢰도를 추정하는 방법과 설계 신뢰도를 추정한 결과를 나타내었다. LEEFI형 착화장치에서 비행편 속도는 화약 기폭에 중대한 영향을 미친다. 복잡한 물리적 현상으로 비행편의 속도가 발생하기 때문에 문헌에 공개된 역학적 모델을 이용하여 비행편 속도를 평가하는 데 많은 연산 시간이 필요하다. 또한 높은 신뢰도를 가지는 착화기는 요구되는 신뢰수준이 증가할수록 신뢰도 평가에 연산 비용이 증가한다. 따라서 설계 신뢰도 추정시 연산 효율성을 증가시키기 위하여 시간에 따른 비행편 속도에 대한 메타모델을 구축하였다. 구축한 메타모델을 이용하여 설계 변수의 다양한 분포 및 시그마 수준에 따른 설계 신뢰도를 추정한 결과를 나타내었다. 그리고 제안하는 추정 방법에 대한 연산 효율성과 정확성을 분석하였다.

• 에너지공학
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• 제28권1호
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• pp.1-9
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• 2019

석탄 화력발전소의 배연탈황공정에서 탈황용 흡수제로 사용하는 석회석을 대상으로 본드의 분쇄일지수(BWI) 및 하드그로브지수(HGI) 측정 후 분쇄효율을 비교하였다. 측정결과, 국내 탈황용 석회석의 분쇄성지수는 HGI가 증가함에 따라 BWI가 감소하는 선형적인 반비례 관계를 확인할 수 있었으며, 석회석의 화학조성 및 채광위치에 따른 결정구조에 따라 분쇄효율의 차이가 발생하였다. 이에 따라, 석회석의 분쇄성을 측정할 경우 측정방법이 까다롭고 시간이 오래 걸리는 BWI 보다 간편하게 측정할 수 있는 HGI를 활용하여도 시료의 분쇄성 차이를 확인할 수 있을 것으로 사료되며, 분쇄 특성에 따른 석회석의 선택적 활용 시 탈황효율 또한 향상시킬 수 있을 것으로 판단된다.

• Asian Journal of Atmospheric Environment
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• 제5권4호
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• pp.228-236
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• 2011

Since most Green House Gases (GHGs) and air pollutants are generated from the same sources, it will be cost-effective to develop a GHGs reduction plan in combination with simultaneous removal of air pollutants. However, effects on air pollutants reduction according to implementing any GHG abatement plans have been rarely studied. Reflecting simultaneous removal of air pollutants along with the GHGs emission reduction, this study investigated relative cost effectiveness among GHGs reduction action plans in Busan Metropolitan City. We employed the Data Envelopment Analysis (DEA), a methodology that evaluates relative efficiency of decision-making units (DMUs) producing multiple outputs with multiple inputs, for the investigation. Assigning each GHGs reduction action plan to a DMU, implementation cost of each GHGs reduction action plan to an input, and reduction potential of GHGs and air pollutants by each GHGs reduction action plan to an output, we calculated efficiency scores for each GHGs reduction action plan. When the simultaneous removal of air pollutants with the GHGs reduction were considered, green house supply-insulation improvement and intelligent transportation system (ITS) projects had high efficiency scores for cost-positive action plans. For cost-negative action plans, green start network formation and running, and daily car use control program had high efficiency scores. When only the GHGs reduction was considered, project priority orders based on efficiency scores were somewhat different from those when both the removal of air pollutants and GHGs reduction were considered at the same time. The expected action plan priority difference is attributed to great difference of air pollutants reduction potential according to types of energy sources to be reduced.

• 펄프종이기술
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• 제44권4호
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• pp.85-90
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• 2012

Wet pressing process has great influence not only on the paper properties but also on the efficiency of total manufacturing process including energy efficiency. The slow drainage propensity of old corrugated container(OCC) might require more complicated control of wet pressing process. In this study, the change in press efficiency and in structure of wet sheet by the various condition of laboratory roll press simulator were evaluated to provide background information about wet pressing of OCC. The higher pressure and the slower machine speed resulted in higher efficiency of wet pressing but the change trends of dryness depending on the wet press pressure and machine speed were shown differently according to OCC treatment. The effects of water contents of felt on the wet press efficiency and sheet structure were also investigated. The higher contents of water in felt resulted in less removal of water generally and the crushed structure of wet sheet were appeared especially at higher pressure.

• 에너지공학
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• 제21권4호
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• pp.356-361
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• 2012

지열, 풍력, 태양열에너지 등과 같은 신재생에너지 분야에 관한 연구가 활발히 이루어지고 있으나 전체 에너지 중에서 차지하는 비율은 아직 미미하다. 본 논문은 주열원인 열사이폰관형 태양열집열기와 보조열원인 X-L 파이프 보일러장치를 서로 결합한 하이브리드 난방시스템에 관한 연구이다. 특히 새로운 형태의 열사이폰관형 태양열집열기에 관한 성능 평가와 함께 보조열원장치의 성능 및 안전성에 대해 조사하였다. 그 결과, 열사이폰관형 태양열집열기는 이중관형 태양열집열기보다 집열효율이 그 구조적 특성 때문에 최대 20.7% 더 증가하였다. 또한 보조열원장치의 X-L 파이프 내 특수열매체는 순수 물보다 약 20% 더 빠르게 온도가 상승하였으며, X-L 파이프 보일러는 안정성 때문에 팽창압력 해소장치가 필요함을 확인하였다.

• 한국환경과학회지
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• 제9권6호
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• pp.449-454
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• 2000

Sustainable development has been the key concept, both in economic policies and in environmental management. On the basis of an systems ecology perspective, this suggests the sustainable development of Korea\`s natural environment and economic activity using the EMERGY evaluation. The total EMERGY use(7,730E20sej/yr) in Korea is 81 percent from imported sources, fuels and goods and services. The ratio of outside investment to attracting natural resources is already large, like other industrialized countries. Continued availability of purchased inputs at a favorable balance of EMERGY trade, currently about 2.85 to 1 net EMERGY, tis the basis for present economic activity and must decrease as the net EMERGY of purchased inputs including fossil fuels goes down. EMERGY yield ratio and environmental loading ratio were 1.23 and 20.30, respectively. The population level is already in excess of carrying capacity. Its carrying capacity for steady state on its renewable sources is only 2.2 million people, compared to 45.9 million in 1977. EMERGY sustainability index is therefore less than one, which is indicative of highly developed consumer oriented economies. Until now the development of a country has been achieved by the economic growth, but it can be sustained in the long run by the use of renewable resource systems. the efficiency of energy usage, and the transformation of the social-economic structure based on an ecological-recycling concept.

• 한국주거학회논문집
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• 제21권1호
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• pp.1-9
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• 2010

Housing problems in city have being caused social contradiction that contains social discord and conflict between poor and rich. And they have raised one of social problems including a disequilibrium of demand and supply, a housing trouble, and a poor residential environment. Therefore, the purpose of this study is to suggest to the improvement of social housing that exposes to a poor environment for social integration. For this, this study is to extract environmental-friendly design factors for each building phase by in-depth evaluation of experts, and to analyze the problems of domestic social housing and environment-friendly design factors considered prior literature. The results as follow. It might be considered highly phase of schematic design, The building construction, and performance management having factors. Specially, it analyzed to 'Living Environment', 'Economic Efficiency', and 'renewable Energy Systems' should be considered highly. Ultimately, this study would be reconsidered the improvement of social housing proposed by the Government for the social outcast.

• International Journal of Railway
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• 제7권2호
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• pp.35-39
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• 2014

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

• KIEAE Journal
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• 제10권1호
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• pp.65-72
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• 2010

The use of natural light has the potential for improving both the energy efficiency and indoor environmental quality in buildings. A light-pipe system can introduce daylight to spaces that would otherwise not be able to benefit from the advantages of daylight penetration. For the light-pipe system to be widely used in Korea, it is important to quantify its daylighting performance with due consideration regarding the effects imposed by the local climate conditions. This paper presents the evaluation results of existing semi-empirical models to predict daylighting performance of a light-pipe system. The evaluation of the existing models was based on the monitoring data obtained from a underground parking lot in which the light-pipe system was installed. Comparisons were made between the predicted and the monitored data obtained from the study. The results indicated that semi-empirical models which was developed using the experimental data obtained under the Korean climatic conditions had a good prediction performance. We also quantified the effects caused by sky conditions, solar altitudes, room dimensions, and the aspect ratio of a light-pipe system on both the daylighting performance of the light-pipe system and the indoor illuminance distributions of the space using the semi-empirical model. Finally, this paper provides the design guideline of the light-pipe system for its application to an underground parking lot space.

• 전기학회논문지
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• 제64권10호
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• pp.1411-1417
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• 2015

The installation of PV system to the power distribution system is being increased as one of solutions for environmental pollution and energy crisis. However, the efficiency of PV system is getting decreased because of the aging phenomenon and several operation obstacles. Therefore, The technology development of aging diagnosis of PV modules are required in order to improve operation performance of PV modules. This paper proposes evaluation algorithm for aging state in PV modules by using the electrical characteristics of PV modules and environmental factors. And also, this paper presents a operation evaluation system of PV modules based on the proposed aging diagnosis algorithm of PV modules. From the simulation results of proposed evaluation system, it is confirmed that the proposed algorithm is a useful tool for aging diagnosis of PV systems.