• 제목/요약/키워드: reflected energy

검색결과 443건 처리시간 0.025초

도시계획단계의 에너지 수요예측 방안에 관한 연구 (A Study on Urban Energy Consumption Estimation on the Urban Planning Stage)

  • 여인애;윤성환
    • 한국태양에너지학회:학술대회논문집
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    • 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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    • pp.506-510
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    • 2012
  • This study suggested an improved algorithm of urban energy consumption estimation on the urban planning stage which concerns calculation accuracy. The results are as follows. (1) Urban energy consumption was estimated and managed per unit space using E-GIS DB which contains facility information per mesh. (2) Urban energy consumption was reflected by the urban facility classified and standardized by the characteristics of energy use. (3) Calculation accuracy of energy consumption was approached by separately suggested as summer algorithm reflecting urban heat island on summer energy use and winter algorithm reflecting heating system normally used in Korea.

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철강산업의 에너지효율 지수개발과 관리기법 연구 (Development of Energy Efficiency Indicator in the Steel Industry)

  • 이상엽;안윤기
    • 자원ㆍ환경경제연구
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    • 제12권1호
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    • pp.29-48
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    • 2003
  • The Steel Industry has made a significant contribution to the increase of energy use in Korea. This paper presents a method for development energy efficiency indicator in the steel industry based on the decomposing approach. This paper develops a logically consistent method for decomposing a change in energy consumption into the effects of three factors structural change, energy intensity and output level. Numerical illustration of the method is given using 1992~2001 data for energy consumption in a virtual works. The most dominant factor is revealed to be the output effect. The energy intensity for the steel industry has increased and the effect of such a growth was relatively strongly reflected in the decomposition analysis. The structural effect turned out to be also important during the periods.

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직선터널에서 지하철 열차의 교차운행 시 반사파 간섭에 따른 유동 특성 비교분석 (Comparative Analysis of Flow Characteristics Using Reflected Pressure Wave at Crossing of Subway Trains in Straight Tunnel)

  • 이득선;조정민;이명호;성재용
    • 설비공학논문집
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    • 제30권3호
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    • pp.123-129
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    • 2018
  • In this study, CFD is used to compare and analyze the flow characteristics using reflected pressure wave during the intersection of two trains in straight tunnel. Two tunnels of different lengths; 600 m and 3,400 m were designed and numerical analysis of the flow characteristics of two tunnels carried out by setting the crossing state of the two trains at a constant velocity of 27 m/s form the center of the tunnel. The simulation model was designed using the actual tunnel and subway dimensions The train motion was achieved by using the moving mesh method. For the numerical analysis, $k-{\omega}$ standard turbulence model and an ideal gas were used to set the flow conditions of three-dimensional, compressible and unsteady state. In the analysis results, it was observed that the inside of the long tunnel without interference of the reflected pressure wave was maintained at a pressure lower than the atmospheric pressure and that the flow direction was determined by the pressure gradient and shear flow. On the other hand, the flow velocity in the short tunnel was faster and the pressure fluctuation was noted to have increased due to the reflected pressure wave, with more vortices formed. In addition, the flow velocity was noted to have changed more irregularly.

복잡한 지형상에서 실시간 피폭해석 시스템 검증 (Validation of a Real-Time Dose Assessment System over Complex Terrain)

  • 서경석;김은한;황원태;최영길;한문희;정성태
    • Journal of Radiation Protection and Research
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    • 제24권1호
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    • pp.31-38
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    • 1999
  • 원자력시설의 사고시 신속한 방재대책 결정지원 체계를 수립하기 위하여 실시간 방사선 피폭해석 시스템(FADAS : Following Accident Dose Assessment System)을 개발하였다. 개발된 시스템의 정확도 향상 및 국내 부지 특성자료의 모수화를 위하여 복잡한 지형상에 위치한 영광 원자력발전소 주변에서 야외 확산실험이 수행되었다. 확산실험을 통하여 얻어진 바람의 평균 및 난류장 성분은 부지 특성별 변수로 실시간 방사선 피폭해석 시스템에 반영되었다. 확산모형의 계산결과와 실험을 통하여 관측된 추적자 가스의 농도분포를 상호 비교한 바 어느 정도 일치하고 있었다. 개발된 시스템은 현재 구축중인 국가 규모의 비상대응지원체제에 기본 모듈로서 활용 중에 있으며 지속적인 확산실험을 통하여 부지 특성 변수들이 반영된 확산모형을 개선할 예정이다.

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SymbioCity관점에서 본 도시재생의 계획적 특성 고찰 : 스웨덴과 독일 사례를 중심으로 (Characteristics of Urban Regeneration Reflected upon SymbioCity Concepts : Focused on Sweden and Germany Examples)

  • 이성희;김정곤
    • 토지주택연구
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    • 제8권4호
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    • pp.275-283
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    • 2017
  • The aim of this study was to present the direction of sustainable urban regeneration through the study of planning characteristics of urban regeneration reflected upon 'SymbioCity' concepts. This study was carried out through theoretical review and case study. In the theoretical review, the theory of 'SymbioCity', one of Sweden's representative urban development models linked to the concept of sustainable development, was reviewed and the framework was derived based on this theory. The framework of this study was finally derived from 'energy', 'ecology and environment', and 'historical and cultural resources'. The case study was conducted by selecting three urban regeneration projects($V{\ddot{a}}strahamnen$ BO01, Royal seaport and HafenCity Hamburg) in Sweden and Germany. Based on the results of case analysis, the direction of sustainable urban regeneration is as follows. First, in terms of energy, we should pay attention to synergy between energy and waste and energy production. Second, in terms of ecology and environment, plans should be made to maximize the use of existing resources in order to conserve natural resources and reduce energy consumption and economic costs. Third, in terms of historical and cultural resources, it is necessary to consider ways to preserve and recycle existing buildings with historical and cultural values. Finally, for the successful application of the planning elements, it is necessary to find the most appropriate application method through steady R&D in the country or project unit.

압력배출구를 설치한 전동화 차량 배터리 시험실의 내부 폭압 평가 (Evaluation of Internal Blast Overpressures in Test Rooms of Elcetric Vehicles Battery with Pressure Relief Vents)

  • 방승기;신진원;정현진
    • 한국지열·수열에너지학회논문집
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    • 제18권3호
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    • pp.7-18
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    • 2022
  • Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△HTNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

반온실형(半溫室型) 제습(除濕).태양열(太陽熱) 목재(木材)드라이어의 일사량(日射量)과 열효율분석(熱效率分析)에 관(關)한 연구(硏究) (Analysis of Solar Radiation and Heat-Efficiency in Semi-Greenhouse Type Solar-Dehumidification Lumber Dryer)

  • 이형우
    • 태양에너지
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    • 제9권3호
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    • pp.3-12
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    • 1989
  • Semi-greenhouse type solar-dehumidification drying of oak was carried out to investigate the possibility to dry wood using solar energy in Korea. The energy balance equation was set up, considering all the energy requirements, and the solar radiation was calculated to analyze the efficiencies of solar dryer with and without the dehumidifier. The average temperature inside dryer and collector rose up to $52^{\circ}C$ and $70^{\circ}C$, respectively. The average daily total beam, diffuse, and ground-reflected radiations were 7.27MJ, 8.70MJ, and 0.33MJ on the roof and 2.08MJ, 4.84MJ, and 5.37MJ on the south wall collector, respectively. Heat efficiency of solar dryer was 14.04% with dehumidifier and 13.13% without dehumidifier. The energy required to remove 1g of water from wood was 0.0289MJ/g in solar-dehumidification drying and 0.0310 MJ/g in semi-greenhouse type solar drying.

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A Study on Recalculating Nuclear Energy Generation Cost Considering Several External Costs

  • Kim, Hyun-Jung;Yee, Eric
    • 동력기계공학회지
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    • 제22권6호
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    • pp.5-10
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    • 2018
  • Nuclear energy issues such as safety and social acceptance can not only influence the production costs of generating nuclear power, but also the external costs that are not reflected in market prices. Consequently, the social issues affiliated with nuclear power, beyond a severe accident, require some form of financial expense. The external social issues considered here are accident risk and realization, regulatory costs, and nuclear energy policy costs. Through several calculations and analyses of these external costs for nuclear power generation, it is concluded that these costs range from 7 to 27 \/kWh. Considering external costs are required for making energy plans, it could have an influence on generation costs.

태양광선 제적추적기법을 이용한 Heliostat 구동축 기구오차에서 기인하는 태양추적오차의 분석 (Analysis of Sun Tracking Error Caused by the Heliostat Driving Axis Geometrical Error Utilizing the Solar Ray Tracing Technique)

  • 박영칠
    • 한국태양에너지학회 논문집
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    • 제29권2호
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    • pp.39-46
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    • 2009
  • Heliostat, as a mirror system tracking the sun's movement, is the most important subsystem determining the efficiency of solar thermal power plant. Thus the accurate sun tracking performance under the various hazardous operating condition, is required. This study presents a methodology of development of the solar ray tracing technique and the application of it in the analysis of sun tracking error due to the heliostat geometrical errors. The geometrical errors considered here are the azimuth axis tilting error and the elevation axis tilting error. We first analyze the geometry of solar ray reflected from the heliostat. Then the point on the receiver, where the solar ray reflected from the heliostat is landed, is computed and compared with the original intended point, which represents the sun tracking error. The result obtained shows that the effect of geometrical error on the sun tracking performance is varying with time(season) and the heliostat location. It also shows that the heliostat located near the solar tower has larger sun tracking error than that of the heliostat located farther.

자기애자 캡의 금구-시멘트 계면 건전성 평가를 위한 초음파법 활용에 대한 연구 (A Study on the Application of Ultrasonic Testing for The Interface Integrity Evaluation between Iron and Cement of Porcelain Insulator Cap)

  • 윤영근;최인혁;손주암;오태근
    • 한국안전학회지
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    • 제33권6호
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    • pp.58-65
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    • 2018
  • The life span of the porcelain insulator was made to be 30 years, but currently many of the 154kV NGK porcelain insulators using in Korea are found to have passed the production life. Accidents caused by aged mechanical breakdown can lead to disruption of power supply in some areas, large economic losses, and casualties. Therefore, ultrasonic method, which is one of the non - destructive test methods, is applied as a method for evaluating the integrity of porcelain insulators. In this study, the experiment on the interface of cap was conducted and the difference between the energy difference and the attenuation coefficient of the reflected wave was derived according to the interface state of the steel - cement. The results of this study are expected to be used as the basic data of the ultrasonic testing to evaluate the interface condition of the porcelain insulator cap.