• 대한설비공학회지:설비저널
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• 제14권1호
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• pp.1-11
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• 1985

Solar/absorption cooling system was analyzed and its operating condition was examined. For the system, the optimum size of absorption refrigerator and collector area should be determined. As the temperature of water supplied to the generator increases, the collector efficiency decreases whereas the coefficient of performance of absorption refrigerator increases up to a certain point, and vice versa for decreasing of the temperature of water supplied to the generator . Thus if the reeling load is given, the appropriate operating condition can be determined between the two opposing trends by simulation program. As an example of the simulation, the case of Jejudo province was studied. Under the conditions (such as weather data and prices of components, etc.) given en the sample calculation, the result shows that the optimum temperature of water supplied to the generator turned out to be $80.3^{\circ}C$, and still shows a large economical disadvantage in present stage compared to the case of conventional vapor compression cooling/heating combined heat pump system.

• 한국농공학회논문집
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• 제52권5호
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• pp.1-9
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• 2010

Evapotranspiration (ET) is one of the basic components of the hydrologic cycle and is essential for estimating irrigation water requirements. In this study, artificial neural network (ANN) models for reference crop evapotranspiration ($ET_0$) estimation were developed on a monthly basis (May~October). The models were trained and tested for Suwon, Korea. Four climate factors, daily maximum temperature ($T_{max}$), daily minimum temperature ($T_{min}$), rainfall (R), and solar radiation (S) were used as the input parameters of the models. The target values of the models were calculated using Food and Agriculture Organization (FAO) Penman-Monteith equation. Future climate data were generated using LARS-WG (Long Ashton Research Station-Weather Generator), stochastic weather generator, based on HadCM3 (Hadley Centre Coupled Model, ver.3) A1B scenario. The evapotranspirations were 549.7 mm/yr in baseline period (1973-2008), 558.1 mm/yr in 2011-2030, 593.0 mm/yr in 2046-2065, and 641.1 mm/yr in 2080-2099. The results showed that the ANN models achieved good performances in estimating future reference crop evapotranspiration.

• 경영과학
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• 제30권2호
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• pp.97-106
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• 2013

Of the new and renewable energies currently being pursued domestically, wind energy, together with solar photovoltaic energy, is a new core growth driver industry of Korea. As of May 2012, 33 wind farms at a capacity of 347.8MW are in operation domestically. The purpose of this study was to compare and analyze how efficiently each operational wind farm is utilizing its power generation capacity and the weather resource of wind. For this purpose, the study proceeded in 3 phases. In phase 1, ANOVA analysis was performed for each wind farm, thereby categorizing farms according to capacity, region, generator manufacturer, and quantity of weather resources available and comparing and analyzing the differences among their operating efficiency. In phase 2, for comparative analysis of the operating efficiency of each farm, Data Envelopment Analysis (DEA) was used to calculate the efficiency index of individual farms. In the final phase, phase 3, regression analysis was used to analyze the effects of weather resources and the operating efficiency of the wind farm on the power generation per unit equipment. Results shows that for wind power generation, only a few farms had relatively high levels of operating efficiency, with most having low efficiency. Regression analysis showed that for wind farms, a 1 hour increase in wind speeds of at least 3m/s resulted in an average increase of 0.0000045MWh in power generation per 1MW generator equipment capacity, and a unit increase in the efficiency scale was found to result in approximately 0.20MWh power generation improvement per unit equipment.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.539-541
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• 2009

A severely cold weather condition of King Sejong Station, Antarctica becomes a very severe condition for an installation/operation of wind generation system. When the existing wind generation system works, it may cause a damage and destruction of wind generation system and can bring about big problems in terms of the power quality. Accordingly, it is essential to obtain technologies for the installation and operation of small wind generation system for the polar region's wind generation, and to assess and demonstrate the performance in the severely-cold environment and the polar wind generation system's development, supplementation, alteration. Also, as the available power of King Sejong Station, Antarctica, the diesel generator has been mainly used, and the wind generator has been used in the hybrid form. Wind generation and diesel generation has the different load following control each other. In the wind generation, the generated power very rapidly changes according to the change of the velocity of the wind. On the other hand, the diesel generation shows very gentle change in the velocity of output. Therefore, the study is intended to analyze the 10kw small wind generator-diesel generator's power quality of King Sejong Station, Antarctica, which is the hybrid system installation area.

• 한국물환경학회지
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• 제24권6호
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• pp.725-740
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• 2008

In this study a multi-site daily precipitation generator which generates the precipitation with similar spatial correlation, and at the same time, with conserving statistical properties of the observed data is developed. The proposed generator is intended to be a tool for down-scaling the data obtained from GCMs or RCMs into local scales. The occurrences of precipitation are simultaneously modeled in multi-sites by 2-parameter first-order Markov chain using random variables of spatially correlated while temporally independent, and then, the amount of precipitation is simulated by 3-parameter mixed exponential probability density function that resolves the issue of maintaining intermittence of precipitation field. This approach is applied to the Nakdong river basin and the observed data are daily precipitation data of 19 locations. The results show that spatial correlations of precipitation series are relatively well simulated and statistical properties of observed precipitation series are simulated properly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.187-191
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• 2004

Photovoltaic and wind power generation have an advantage of unpolluted and unlimited amount of energy resource. Since there is such an advantage in these energies, But photovoltaic system and wind system cannot always generate stable output with ever-changing weather condition. In this paper, the auxiliary power generator for hybrid system(photovoltaic 500[W], wind power generation 400[W]) was suggested. the auxiliary power generator that uses elastic energy of spiral spring to photovoltaic system was also added for present system. when output of photovoltaic system gets lower than 24[V], power was continuously supplied to load through the inverter by charging energy of spiral spring operates in DC generator.

• 한국산학기술학회논문지
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• 제16권9호
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• pp.6419-6424
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• 2015

현재 도서지역에 도입되어 운용되고 있는 풍력-디젤 하이브리드 발전시스템에는 풍속과 부하변동에 대하여 적정범위의 전압주파수를 갖는 전력을 공급하기 위하여 고가의 제어가 복잡한 플라이휘일 또는 배터리 에너지저장장치를 설치운영하고 있다. 그러나, 본 논문은 이와 같이 비경제적이고 복잡도가 높은 에너지저장장치를 설치하지 않고, 풍속 및 부하변동에도 안정적인 운전이 가능한 영구자석형(PMSG: Permanent Magnet Synchronous Generator) 풍력-디젤 복합발전시스템으로 구성되는 독립형 마이크로그리드의 운전제어 알고리즘과 모델링 방법을 제안하였다. 먼저, 부하 및 풍속변동에 관계없이 적정범위의 전압주파수를 유지할 수 있는 PMSG 풍력발전기의 운전제어 알고리즘을 제안하고, 이를 바탕으로 한 전가변속 운전이 가능한 PMSG, WT측 컨버터 및 Grid측 컨버터를 모델링하고, 이를 독립형 마이크로그리드에 적용하여 풍속 및 부하변화에 대하여 전압주파수가 적정범위내로 잘 유지됨을 입증하였다.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.499-509
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• 2019

This paper discusses energy use monitoring and analysis as part of a study on a low-cost energy supply management system that links an existing database with weather information with no real-time monitor for energy demand of buildings using renewable energy, generator and energy storage systems. This study is targeted at small and medium-sized buildings and aims to monitor energy use with a small number of sensors at low cost by applying an energy management system (EMS). The present study can help overcome the limitations of high-cost EMS applied to large commercial and public buildings. We developed current, indoor temperature and human motion sensors and installed them in an office of a company in a sample building. Through these sensors, we analyzed energy use patterns and the effects of weather information and human motion on the energy use. Furthermore, we analyzed the correlations between the total KEPCO energy use of the sample building and weather by comparing these two data. The results showed that the office energy use of a company was more affected by human motions than by weather information. The comparison between the total energy use of the Building and weather information found that external temperature had an effect on the energy use.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.365-368
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• 2006

The objective of this research is to investigate usage of 3KW photovoltaic-wind power hybrid generation system composed of 500W solar power generator and 400W wind power generator in a parallel circuit. In addition, solar radiation meter and wind monitor have been installed into each generation system to obtain the practical operating data that monitored in monthly, daily and hourly. These data that are independent to weather change and location would provide adequate generation output on average and cope with emergency situation in generation system In conclusion, based on this study, it could be considered for 3KW combined generation system to be gradually propagated to houses and small-size public facilities.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1504-1506
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• 2004

Photovoltaic and wind power generation have an advantage of unpolluted and unlimited amount of energy resource. Since there is such an advantage in these energies, But photovoltaic system and wind system cannot always generate stable output with ever-changing weather condition. In this paper, the auxiliary power generator for hybrid system(photovoltaic 500[W], wind power generation 400[W]) was suggested. the auxiliary power generator that uses elastic energy of spiral spring to photovoltaic system was also added for present system. when output of photovoltaic system gets lower than 24[V], power was continuously supplied to load through the inverter by charging energy of spiral spring operates in DC generator.