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나노유체를 적용한 태양열집열시스템 열전달 성능향상 연구
손지훈(J. H. Son),정정열(J. Y. Jung),이호생(H. S. Lee),김현주(H. J. Kim) 한국해양환경·에너지학회 2013 한국해양환경·에너지학회 학술대회논문집 Vol.2013 No.11
해양온도차발전의 경우 적도 및 아열대 해역에서는 1년 내내 효율이 유지가 되지만, 고위도에서는 하절기와 달리 동절기에는 표층수의 온도가 떨어져 심층수와의 적정온도차를 만족하지 못해 효율이 하락하는 등의 문제점이 발생함으로 인해 동절기에 해양온도차발전 운전시 해양표층수를 대체할 온열원의 공급이 필요하다. 동절기에 해양온도차발전의 온열원 확보를 위해 같은 전력으로도 좀 더 높은 온도의 온열원 공급을 위해 산화알루미늄 나노유체를 태양열집열시스템에 적용하였다. 이에 본 연구에서는 평판형 태양열집열기를 기반으로 하는 태양열집열시스템의 큰 관을 적용하여 실험장치 2개 set를 제작하였고, 실제 태양열의 평균일사량 대비 평판형 태양열집열기의 평균 집열열량을 기준으로 가동을 하여 순수물과 산화알루미늄 나노유체의 비율별 가동실험을 수행하여 열전달 성능을 비교하였다. In case of OTEC, its efficiency is maintained all through the year in tropical and subtropical regions. However in high latitude region, the efficiency of OTEC decreases due to less temperature difference between surface and deep waters in winter while the temperature difference is enough for OTEC in summer. Because the temperature of surface water goes down in winter, an additional heat source is necessary to compensate the energy of surface water to operate OTEC. In this study, solar energy is considered as the additional heat source because it is the most abundant energy resource on earth. Also nanofluid, a colloid with suspended nanoparticles, is used to enhance the heat transfer rate of solar collecting system. Al2O3/water nanofluids were prepared to used as an working fluid for solar collecting system. We installed same two sets of solar collecting system with flat-plate solar collectors and carried out experiments to compare heat transfer performances of pure water and Al2O3/water nanofluids.
연구논문 : 기존 도시의 홍수저감을 위한 우수관거 배수용량 증대 및 지하 빗물저류조 설치효과 비교 분석
이호열 ( Ho Yeol Lee ),서규태 ( Gyu Tae Seo ),이택순 ( Taek Soon Lee ) 한국물환경학회(구 한국수질보전학회) 2013 한국물환경학회지 Vol.29 No.6
Urban floods are usually caused by the lack of drainage capacity. Hence, sewer capacity expansion methodology by replacing small pipes with bigger ones is primarily applied as a flood control measure. However, this approach is often unreasonable because of the costs and time involved. Thus, the installation of underground rainwater storage tanks with the two advantages of flood control and water conservation is proposed. This study compared the effectiveness of flood control by both the sewer expansion methodology and rainwater storage tanks using the Storm Water Management Model. Three cases were simulated in this study. The first case analyzed flood reduction by the storm sewer expansion methodology. The simulation results indicate that the overflow volume from manholes was reduced by 49% with this methodology. The second case analyzed flood reduction by installation of rainwater storage tank. The simulation results indicate that the overflow volume was reduced by 62%. However, these two cases could not prevent urban floods completely. Hence, the third case analyzed the joint application of the storm sewer expansion methodology and rainwater storage tanks. In this simulation, flooding did not occur. Consequently, the results of this study clearly show that underground rainwater storage tanks are more effective for flood control than capacity expansion of storm sewer. Furthermore, the joint application of these two flood control measures is more effective than their separate application.
수평․수직연소 시험법에 의한 EPS 단열재의 연소성능 특성
이호열(Ho-yeol Lee),강재식(Jae-Sik Kang),최현중(Hyun-Jung Choi) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.6
Organic thermal insulation such as cellular polystyrene insulation is mainly used in buildings. Organic thermal insulation is a highly flammable petrochemical material. Because of such characteristics, organic thermal insulation caused fire accident for buildings. The inflammability of cellular polystyrene insulation specified by Korea standard KS M 3808:2011, "Cellular polystyrene(PS) insulation": combustion time ≤ 120 seconds, combustion length ≤ 60 ㎜ through Korea standard KS M ISO 9772:2013, "Cellular plastics - Determination of horizontal burning characteristics of small specimens subjected to a small flame". In this study, horizontal and vertical burning test (KS M ISO 9772 and UL 94 V, respectively) were analyzed about many cellular polystyrene insulations. As a results, horizontal burning test is very little differentiation the flame-retardant performance levels. However, vertical burning test is not like that. To better assess the level of the flame-retardant performance, the current standard needs to be improved.
적층형 4-BAR 메커니즘을 이용한 평면형 메니퓰레이터
이호열(Hoyul Lee),최영진(Youngjin Choi) 제어로봇시스템학회 2010 제어·로봇·시스템학회 논문지 Vol.16 No.5
This paper proposes a new planar robotic manipulator using stackable 4-BAR mechanisms for various applications. The proposed manipulator has an advantage that we can separate the driving actuators from a robotic manipulator. By separating actuators from the manipulator, we are able to separate the electrical component such as electrical wiring from the mechanical linkage/joint components in the robotic manipulator. Also, we suggest the kinematic analysis of the proposed manipulator which is composed of input mechanisms, multiple 4-BAR mechanisms and output mechanisms. Finally, we suggest numerical simulations to show the effectiveness of the proposed manipulator.
이호열(Ho Yeol Lee),최승복(Seung bok Choi),최돈묵(Don Mook Choi) 한국화재소방학회 2021 한국화재소방학회논문지 Vol.35 No.1
본 연구는 시간 흐름에 따른 스프링클러설비의 일상적 유지관리 제도의 문제점과 개선방안을 제시하기 위해 유지관리의 개념과 제도적 현황을 알아보고, 수도권 내 건축물에 설치된 스프링클러설비의 작동기능점검과 소방안전관리 업무 대행 시 작성한 불량 내용의 분석을 통해 실태조사를 하였다. 이에 따른 개선방안으로 유지관리 지침서제정, 소방안전관리 업무 대행에 관한 업무 규정, 불량 내용 처리 및 업무 대행 감독자의 교육 강화 등의 법률 제정과유지관리행위의 효율성 제고를 위한 공간 수치화 및 부식 및 침수 피해를 방지할 수 있는 공간 구축 등의 관련 법제도의 정비가 필요하다. The maintenance and status of institutional maintenance of sprinkler facilities are examined to identify problems andsuggest improvement plans for the daily maintenance system for sprinkler facilities over time. In addition, the details ofpoor inspection practices of sprinkler facilities installed in buildings in the Seoul metropolitan area and records preparedby the agency for fire safety management are analyzed. Suggested improvement measures include drafting legislation toestablish maintenance guidelines, standardizing work on fire safety management, handling defective contents, strengtheningeducation of business supervisors, and establishing a maintenance space to prevent corrosion and flooding.