• 제목/요약/키워드: Wind energy

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연축전지와 리튬이온전지용 하이브리드 ESS의 최적구성방안에 관한 연구 (A Study on Estimation Method for Optimal Composition Rate of Hybrid ESS Using Lead-acid and Lithium-ion Batteries)

  • 박수영;유상원;박재범;김병기;김미영;노대석
    • 전기학회논문지
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    • 제65권6호
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    • pp.962-968
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    • 2016
  • The large scaled lead-acid battery is widely used for efficient operation of the photovoltaic system in many islands. However, lithium-ion battery is now being introduced to mitigate the fluctuation of wind power and to replace lead-acid battery. Therefore, hybrid ESS(Energy Storage system) that combines lithium-ion battery with lead-acid battery is being required because lithium-ion battery is costly in present stage. Under this circumstance, this paper presents the optimal algorithm to create composition rate of hybrid ESS by considering fixed and variable costs in order to maximize advantage of each battery. With minimization of total cost including fixed and variable costs, the optimal composition rate can be calculated based on the various scenarios such as load variation, life cycle and cost trend. From simulation results, it is confirmed that the proposed algorithms are an effective tool to produce a optimal composition rate.

혈전증(血栓症) 및 고점도혈증(高粘度血症)에 대(對)한 당귀음(當歸飮)과 이진탕(二陳湯)의 실험적(實驗的) 연구(硏究) (Studies on the Effects of Danggieum and Ijintang on Thrombosis and Elevated Blood Viscosity)

  • 김영석
    • 대한한의학회지
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    • 제15권2호
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    • pp.212-232
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    • 1994
  • I selected the theory of blood stasis and wetness-phlegm among the major 4 causes of Joong Poong(C.V.A.)(wind. fire. deficiency of vital energy and wetness-phlegm) and recent etiology of blood stasis. An experimental studies were done to investigate the effects of Danggieum (removing blood stasis and promoting blood circulation) and Ijintang(dissipating wetness-phlegm) on thrombosis and elevated blood viscosity. The results were as follows; 1. The number of platelets were significantly increased in only Danggieum group. 2. Related to the amount of fibrinogen. only Danggieum group revealed some increase. but both groups revealed no significance. 3. Related to the prothrombin time. Danggieum and Ijintang groups had significant decrease. but Danggieum group revealed more significance. 4. Related to the degree of concentration of FDP, only Danggieum group had significant decrease. 5. Whole blood viscosity and plasma viscosity in lower shear rates. both groups of Danggieum and Ijintang had significant decrease. 6. Related to the amount of RBC. both groups of Danggieum and Ijintang had significant decrease. 7. Related to the change of hematocrit. only Danggieum group, and the change of hemoglobin. only Ijintang group had significant decrease. 8. Related to the change of body temperature. only Ijintang group had significant raise. 9. Related to the changes of WBC. glucose, albumin, total protein and body weight. Danggieum and Ijintang groups had each increase or decrease. but no significance. According to the above results, Danggieum had more significant effect than Ijintang on the thrombosis. and Ijintang had more significant effect than Danggieum on the elevated blood viscosity. And it is considered that it might be more effective in treating Joong-Poong(C.V.A) to take medicines regarding patient's constitution and symptoms as well as the causes of Joong-Poong(C.V.A)

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열전달 모델을 이용한 폐수처리공정의 온도 예측 (Temperature Prediction for the Wastewater Treatment Process using Heat Transfer Model)

  • 노승백
    • 한국산학기술학회논문지
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    • 제15권3호
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    • pp.1795-1800
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    • 2014
  • 본 논문은 생물학적 활성오니 폐수처리공정의 열전달 모델식을 제시하여 공정의 온도를 예측하였다. 열전달 모델은 폐수처리공정에 들어오고 나가는 모든 열을 고려하였다. 공정에 들어오는 열은 태양 복사열과 포기조 impeller의 기계적 에너지의 변환열, 포기조 내의 생화학 반응열이다. 공정에서 나가는 열은 폐수 자체의 복사열, 포기작용에 의한 증발열과 포기조 표면으로 나가는 전도열, 바람에 의한 대류열, 포기조와 지표면과의 전도열을 고려하였다. 들어오고 나가는 모든 열은 기존의 열전달 경험식을 적용하였다. 적용된 경험식으로 폐수처리장 공정의 열전달 모델식을 제시하였다. 모델식으로 실제 폐수처리공정의 온도를 예측하였으며, 모델식 예측치와 실제값이 $1.0^{\circ}C$ 이내로 일치하였다.

장마전선 상에서 발생한 중규모 호우계 구조에 대한 연구 (Structure of Mesoscale Heavy Precipitation Systems Originated from the Changma Front)

  • 박창근;이태영
    • 대기
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    • 제18권4호
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    • pp.317-338
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    • 2008
  • Analyses of observational data and numerical simulations were performed to understand the mechanism of MCSs (Mesoscale Convective Systems) occurred on 13-14 July 2004 over Jindo area of the Korean Peninsula. Observations indicated that synoptic environment was favorable for the occurrence of heavy rainfall. This heavy rainfall appeared to have been enhanced by convergence around the Changma front and synoptic scale lifting. From the analyses of storm environment using Haenam upper-air observation data, it was confirmed that strong convective instability was present around the Jindo area. Instability indices such as K-index, SSI-index showed favorable condition for strong convection. In addition, warm advection in the lower troposphere and cold advection in the middle troposphere were detected from wind profiler data. The size of storm, that produced heavy rainfall over Jindo area, was smaller than $50{\times}50km^2$ according to radar observation. The storm developed more than 10 km in height, but high reflectivity (rain rate 30 mm/hr) was limited under 6 km. It can be judged that convection cells, which form cloud clusters, occurred on the inflow area of the Changma front. In numerical simulation, high CAPE (Convective Available Potential Energy) was found in the southwest of the Korean Peninsula. However, heavy rainfall was restricted to the Jindo area with high CIN (Convective INhibition) and high CAPE. From the observations of vertical drop size distribution from MRR (Micro Rain Radar) and the analyses of numerically simulated hydrometeors such as graupel etc., it can be inferred that melted graupels enhanced collision and coalescence process of heavy precipitation systems.

ARPS 모형 지면 과정 모수화에 위성 자료의 응용 (The Application of Satellite Data to Land Surface Process Parameterization in ARPS Model)

  • 하경자;서애숙;정효상
    • 한국지리정보학회지
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    • 제1권1호
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    • pp.99-108
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    • 1998
  • 국지 기상 모형의 지표 특성을 표현하기 위해 토양 구분, 식생 구분, 지표 거칠기 길이, 지표 알베도와 엽면지수가 지면 과정 모수화 내에서 처방되어야 한다. 이 연구에서는 인공위성 관측값으로부터 계절함수로 얻어진 경,위도 1도 및 1도의 엽면지수, 지표거칠기 길이, 눈이 없을 때의 지표 알베도와 상세 격자 NDVI를 지면 과정 모형에 적용하였다. 생물권과 대기권 사이, 지면과 대기 사이의 상호작용에서 이러한 인공위성 자료를 사용한 것과 사용하지 않은 것을 비교함으로써, 열, 에너지 및 수증기 속들, 지면 기온, 바람, 식생 물함유량, 비습, 강수장의 민감도가 조사되었다.

2008년 광주지역 검댕입자 특성 및 광학적 산란효과 보상 (Characteristics of Black Carbon in PM2.5 Observed in Gwangju for Year 2008 and Examination of Filter Loading Effect)

  • 정정훈;박승식
    • 한국대기환경학회지
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    • 제26권4호
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    • pp.392-402
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    • 2010
  • Black carbon (BC) concentrations were measured with an aethalometer (AE-16, 880 nm) at time interval of 5-min at an urban site of Gwangju over a year 2008. 24-hr filter-based integrated measurements of $PM_{2.5}$ particles were also made at the same site during the winter and summer intensive periods to test any optical loading bias in the raw BC data measured by aethalometer. BC concentration was higher in winter than in summer, possibly due to increase in emissions from energy consumption and poor dispersion with reduction of boundary layer in winter. Also temporal cycles of BC indicate that short-term transient spikes were common, occurring primarily during the rush-hour periods. A similar feature was also observed in diurnal concentration cycle of CO, mainly emitted from motor vehicles. When both low wind speed and weather patterns such as mist, haze and etc were combined, high BC concentrations frequently occurred. The amount of optical loading effect described by the "k" factor showed the seasonal variation, ranging from 0.0003 to 0.0036. This implies that optical loading effect is not seen at all times. From the comparison between the filter-based elemental carbon (EC) and aethalometer BC data, it was found that the loading compensated BC values were more reasonable than the raw BC ones reported from the aethalometer.

도시공원녹지의 생태성 및 기후변화 대응성 평가 기초 연구 (A Preliminary Study on Assessment of Urban Parks and Green Zones of Ecological Attributes and Responsiveness to Climate Change)

  • 성현찬;황소영
    • 한국환경복원기술학회지
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    • 제16권3호
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    • pp.107-117
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    • 2013
  • Problems in regard of ecological stability of urban ecosystem ensue from climate change and urbanization. Particularly, urban ecological conditions are deteriorating both quantitatively and qualitatively to a great extent. The present study aims to assess the current condition of selected sites (i. e. urban green zones and parks) in terms of preset assessment components; to find out problems and relevant solutions to improve the quality and quantity of parks and green zones; and ultimately to suggest some measures applicable to coping with climate change as well as to securing the ecological attributes of urban green zones and parks. According to the findings of this study, from quantitative perspectives, ecological attributes and responsiveness to climate change are high on account of the large natural-soil area(80%). By contrast, from qualitative perspectives including the planting structure (1 layer: 47%), the percentage of bush area(17%), the connectivity with surrounding green zones (independent types: 44%), the wind paths considered (5.6%), the tree species with high carbon absorption rates (20%), water cycles (17%), energy (8%) and carbon storage capacities(61%), ecological attributes and responsiveness to climate change were found very low. These findings suggest that the ecological values of urban parks and green zones should be improved in the future by conserving their original forms, securing natural-soil grounds and employing multi-layered planting structures and water bodies, and that responsiveness to climate change should be enhanced by planting tree species with high carbon storage capacities and obtaining detention ponds. In sum, robust efforts should be exerted in the initial planning stages, and sustained, to apply the methodology of green-zone development along with securing ecological attributes and responsiveness to climate change.

Prediction of Fluid-borne Noise Transmission Using AcuSolve and OptiStruct

  • Barton, Michael;Corson, David;Mandal, Dilip;Han, Kyeong-Hee
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2014년도 추계학술대회 논문집
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    • pp.557-561
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    • 2014
  • In this work, Altair Engineering's vibroacoustic modeling approach is used to simulate the acoustic signature of a simplified automobile in a wind tunnel. The modeling approach relies on a two step procedure involving simulation and extraction of acoustic sources using a high fidelity Computational Fluid Dynamics (CFD) simulation followed by propagation of the acoustic energy within the structure and passenger compartment using a structural dynamics solver. The tools necessary to complete this process are contained within Altair's HyperWorks CAE software suite. The CFD simulations are performed using AcuSolve and the structural simulations are performed using OptiStruct. This vibroacoustics simulation methodology relies on calculation of the acoustic sources from the flow solution computed by AcuSolve. The sources are based on Lighthill's analogy and are sampled directly on the acoustic mesh. Once the acoustic sources have been computed, they are transformed into the frequency domain using a Fast Fourier Transform (FFT) with advanced sampling and are subsequently used in the structural acoustics model. Although this approach does require the CFD solver to have knowledge of the acoustic simulation domain a priori, it avoids modeling errors introduced by evaluation of the acoustic source terms using dissimilar meshes and numerical methods. The aforementioned modeling approach is demonstrated on the Hyundai Simplified Model (HSM) geometry in this work. This geometry contains flow features that are representative of the dominant noise sources in a typical automobile design; namely vortex shedding from the passenger compartment A-pillar and bluff body shedding from the side view mirrors. The geometry also contains a thick poroelastic material on the interior that acts to reduce the acoustic noise. This material is modeled using a Biot material formulation during the structural acoustic simulation. Successful prediction of the acoustic noise within the HSM geometry serves to validate the vibroacoustic modeling approach for automotive applications.

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기술자립형 5kW급 건물용 연료전지시스템 안전성능 평가 (Safety Performance Evaluation of Technical Independence 5kW Class Fuel Cell System)

  • 이정운;김영규
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2011년도 추계학술대회 초록집
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    • pp.82.1-82.1
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    • 2011
  • 최근 국내에서 발생된 대규모 정전사태로 인해 안정적인 전력공급에 대한 국민들의 요구가 커져, 지난 3월 일본 후쿠시마 원전사고 이후 다시 한번 분산전원에 대한 필요성이 대두되어지고 있다. 여러 분산전원 중 연료전지는 다른 에너지원에 비해 에너지의 지속성이 우수하여 가장 안정적인 분산전원 형태의 하나이다. 이에 따라 국내의 경우 우수한 도시가스 인프라로 인해 건물용 연료전지라는 신기술에 대한 국민의 수용성은 점점 높아질 것으로 기대된다. 현재 건물용 연료전지의 경우, 주로 1kW급 연료전지가 시범보급되어 각 가정에 설치되어지고 있으나, 상가, 주유소 및 편의점 등의 상업시설과 생활관 및 소형빌라 등의 집단 주거시설 같은 1kW급 보다 용량을 더 필요로 하는 응용처에 국내에서 개발된 5kW급 연료전지시스템이 적용되어지기를 기대한다. 본 연구에서는 국내 제작된 5kW급 고분자전해질 연료전지시스템의 보급이전에 안전성능 평가를 통해 시스템의 성능 및 안전성 평가결과를 제조사에 피드백 하여 5kW급 건물용 연료전지시스템의 조기 상업화에 앞장서고자 한다. 5kW급 연료전지시스템의 기술개발은 핵심부품인 연료변환기, 스택 및 BOP 기술의 경우 1kW급 연료전지시스템에 적용된 것과는 다른 기술이 필요하고, 단순한 scale-up 과정이 아닌 새로운 기술개발로 제품에 적용시켜야 하는 난점을 가지고 있다. 특히, 연료변환기의 경우 연료 유량의 증가로 인하여 reformer, CO shift 및 Prox 반응기의 유체역학, 열교환 흐름 및 촉매반응 공학적으로 이론을 응용한 새로운 반응기 설계와 제작기술 확립이 선행되어 전체적인 시스템 제작 설계에 반영되어져야 한다. 그러므로 본 연구에서는 연료전지시스템 안전성능 평가를 위해 용량증대에 따른 안전성평가 항목을 검토하고, 5kW급 연료전지시스템평가를 수행하여 시스템의 제품성능, 작동성능 및 계통연계성능에서의 안전성을 확인하였고, 정전 유풍과 같은 이상조건 및 실외 환경에 대한 시스템의 안전성도 확인하였다. 또한 부하운전 조건을 75% 및 50%로 변화시켰을 때 빠른 응답시간과 안정적인 부하변동운전을 확인하였다.

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다양한 운전조건에 따른 하이브리드 자동차의 연비 특성 연구 (The study for fuel economy characteristics of hybrid electric vehicle (HEV) according to the driving condition)

  • 이민호;김성우;김정환;김기호;정충섭;노경완;장광식
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2011년도 추계학술대회 초록집
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    • pp.104-104
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    • 2011
  • The fuel economy estimates essentially serve two purposes : to provide consumers with a basis on which to compare the fuel economy of different vehicles, and to provide consumers with a reasonable estimate of the range of fuel economy they can expect to achieve. The current fuel economy label values utilize measured fuel economy over city driving cycles. However, this test driving mode can not be evaluated the variety factor of the real-world. These factors include differences between the way vehicles are driven on the road and over the test cycles, air conditioning use, widely varying ambient temperature and humidity, widely varying trip lengths, wind, precipitation, rough road conditions, hills, etc. The purpose of this paper is to account for three of these factors on the fuel economy : 1) on-road driving patterns (i.e. higher speeds and more aggressive driving (higher acceleration rates)), 2) air conditioning, and 3) colder temperatures. The new test methods will bring into the fuel economy estimates the test results from the five emissions tests in place today : CVS-75, HWFET, US06, SC03 and Cold CVS-75. Based on these new test methods, this paper discusses the characteristics of driving condition on Hybrid electric vehicle (HEV). And this paper assesses the fuel economy label of HEV.

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