• Title/Summary/Keyword: Annual Load

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Comparison Analysis of Turbulence Intensity and Fatigue Load of Onshore Wind Farms According to Terrain (지형에 따른 육상풍력발전단지 난류강도 및 피로 하중 비교 분석)

  • Yeong-Hwi Kim;Minji Kim;Insu Paek
    • Journal of Wind Energy
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    • v.14 no.4
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    • pp.57-67
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    • 2023
  • This study aimed to investigate differences in turbulence intensity and turbine loads among onshore wind farms located in various types of terrain. To achieve this, simulations were conducted for two onshore wind farms with identical wind turbines and capacity but situated on complex and flat terrains. The simulations used meteorological data gathered over a 10-year period from automatic weather stations nearest to the wind farms. WindSim and WindPRO software tools were employed for wind field and load analysis, respectively. The simulation results revealed that wind farm A, situated on complex terrain, exhibited significantly higher effective turbulence intensity than wind farm B on flat terrain, as expected. Consequently, the load indices of several wind turbines exceeded 100 % in wind farm A, indicating that the turbines could not reach their design lifespan. From the simulation study, aimed at reducing both the effective turbulence intensity and turbine loads, it became evident that while increasing turbine spacing could decrease effective turbulence intensity to some extent, it couldn't completely resolve the issue due to the inherently high ambient turbulence intensity on complex terrain. The problem with wind turbine loads could only be completely resolved by using wind turbines with a turbine class of A+, corresponding to a reference turbulence intensity of 0.18.

A Study on the Electrical Load Matching Analisys for the optimal utilization of grid-conntected PV system in Apartment Complex (공동주택의 태양광시스템 적용성 평가를 위한 전기부하 매칭 해석연구)

  • Yoon, Jong-Ho;Park, Jae-Sung;Shin, U-Cheul;Park, Jae-Wan
    • 한국태양에너지학회:학술대회논문집
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    • 2008.04a
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    • pp.49-54
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    • 2008
  • This study is to investigate an optimal size and position of PV system for apartment complex enough the electrical load matching analysis. The 4 types of arrangements of apartment buildings are considered as follows; ㅡtype, alternative ㅡtype, ㄱtype and ㅁtype. We assume that the studied site is composed of 9 buildings. Firstly, solar access evaluation of roof and facade in apartment buildings was performing with the hourly simulations of total received insolation on each surface considering the hading effect of buildings. Electrical load profile of typical Korean apartments was investigated for the lad matching analysis. To calculate an annual total PV output, we used MERIT program which is a sourly based load matching tool developed by ESRU. TRY weather data of Daejeon are applied for this analysis. Result shows that approximately 11% of total electric load of the site can be supplied by the PV system in the case of full installation of PV system at the whole south-face roof area of 9 buildings in this stuided apartment complex. Depending of a various installation option of roof and facade area, the possible ratio of PV supply in total electrical load varies from 9% to 42%. Among the 4 arrangement types, the ㅡ type revealed the best option for the maximum output of PV system.

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Characteristics of Runoff Load from Nonpoint Source Pollutants in the Lake Doam Watershed (도암호 유역에서 비점오염물질의 유출부하 특성)

  • Kwak, Sungjin;Bhattrai, Bal Dev;Gim, Giyoung;Kang, Phil-Goo;Heo, Woomyung
    • Korean Journal of Ecology and Environment
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    • v.51 no.1
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    • pp.135-147
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    • 2018
  • In order to investigate the runoff characteristics of nonpoint source pollutants in the Lake Doam watershed, water quality and flow rate were monitored for 38-rainfall events from 2009 to 2016. The EMC values of SS, COD, TN and TP were in the range of 33~2,169, 3.5~56.9, 0.09~7.65 and $0.06{\sim}2.21mg\;L^{-1}$, respectively. As a result of analyzing the effect of rainfall factor on the nonpoint source pollutant load, EMCs of SS, COD and TP showed a statistically significant correlation with rainfall (RA) (p<0.01) and SS showed highly significant correlation with maximum rainfall intensity (MRI, R=0.48). The load ranges of SS, COD, TN and TP were 10.4~11,984.6, 1.1~724.4, 0.6~51.6 and $0.03{\sim}22.85ton\;event^{-1}$, respectively, showing large variation depending on the characteristics of rainfall events. The effect of rainfall on the load was analyzed. SS, COD and TP showed a positive correlation, but TN did not show any significant correlation. The annual load of SS was the highest with $88,645tons\;year^{-1}$ in 2011 when rainfall was the highest with 1,669 mm. The result of impact analysis of nonpoint source pollution reduction project and land-use change on runoff load showed that pollutant load significantly reduced from 2009 to 2014 but SS and TP loads were increased from 2014 to 2016 due to increase in construction area. Therefore, we suggested that nonpoint source pollution abatement plan should be continued to reduce the soil loss and pollutants during rainfall, and countermeasures to reduce nonpoint source pollution due to construction need to be established.

Analysis of the Part Load Ratio Characteristics and Gas Energy Consumption of a Hot Water Boiler in a Residential Building under Korean Climatic Conditions (국내 기상조건하 주거용 건물 가스 보일러의 부분부하 특성과 에너지 사용량 분석)

  • Yu, Byeong Ho;Seo, Byeong-Mo;Moon, Jin-Woo;Lee, Kwang Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.9
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    • pp.455-462
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    • 2015
  • Residential buildings account for a significant portion of the total building-energy usage in Korea, and a variety of research studies on the domestic boiler have therefore been carried out; however, most of these studies examined the boiler itself, whereby the part-load ratio characteristics and the corresponding gas-energy consumption patterns were not analyzed. In this study, the part-load ratio and operating characteristics of a domestic gas boiler were analyzed within a residential building equipped with a radiant floor-heating system; in addition, the energy consumption between condensing and conventional boilers was comparatively analyzed. Our results show that significant portions of the total operating hours, heating load, and energy consumption are in the part-load ratio range of 0 through 40%, whereby the energy consumption was significantly affected by the boiler efficiency under low part-load conditions. These results indicate that the part-load operation of a boiler is an important factor in residential buildings; furthermore, replacing a conventional boiler with a condensing boiler can reduce annual gas-energy usage by more than 20%.

The Spatial Characteristics of Vertical Accretion Rate in a Coastal Wetland - In case of Sunchon bay estuarine marsh, south coast of Korea - (해안습지 성장률의 공간적 특성에 관한 연구 - 순천만 염하구 해안습지를 사례로 -)

  • Park, Eui-Joon
    • Journal of the Korean association of regional geographers
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    • v.6 no.3
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    • pp.153-168
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    • 2000
  • An estuarine marsh is semi -inclosed inlets, located between coastal and terrestrial environment. The sediment transport by river and tide through tidal river and vertical accretion by sediment accumulation are important processes in estuarine marsh. An analysis of the vertical accretion rate at various time scale is important work for understanding and managing coastal environments. The purpose of this study is to determin the spatial characteristics of vertical accretion rate in an estuarine marsh, Sunchon Bay, in the southern coastal region of Korean peninsula. The methods of analysis are sedimentation rate by individual tidal cycle, annual accretion rate, concentration of total suspended load in water column. Spatial characteristics of sedimentation rate by individual tidal cycle was investigated using 30 filter paper traps. Sedimentation rate by individual tidal cycle at levee edge was higher than that at back marsh. The sedimentation rate decreased with distance from estuarine front. Levee effect and proximity to the turbidity maximum zone result in a higher sedimentation rate in the levee edge. There is a weak relation-ships between tidal regime and sedimentation rate by individual tidal cycle. Spatial cahracteristics of annual accretion rate was investigared using 30 artificial marker plots. Annual accretion rate at back marsh($1.5{\sim}3.5cm/yr$) was higher than that at tidal river levee edge($0.8{\sim}3.0cm/yr$). Total suspended load (TSL) concentrations in water column also indicate this spatial characteristics of annual accretion rate. TSL concentration in water column leaving the vegetation part dramatically decreased. There is a very strong relationship between the concentration of suspended load and accretion rate. These results indicate that annual accretion rate is controlled by vegetation cover and proximity to the turbidity maximum zone. This difference of spatial characteristics of vertical accretion rate ar various time-scale was due to the fact that surface sediment of levee edge was eroded by tide and other factors. The major findings are as follows. First, the spatial characteristics of vertical accretion rate are different from various time-scale. Second, the major mechanism for the vertical accretion rate in this region is suspended load trapping by vegetation. Third, this region is primarily a depositional regime over the time-scale of the present data Fourth, this estuarine marsh is accreting at rates beyond other area.

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Analysis of the Utilization Characteristics of Electrical Power and Equipments on the Farms (농촌의 전력및 전기기기의 이용특성분석)

  • 박승우;류한열
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.17 no.4
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    • pp.3943-3955
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    • 1975
  • The purposes of this study are to evaluate the utilization characteristics of electrical power consumption, to grasp the present trends in the use of electrical equipments, to estimate the demand factor and load factor being held, and to evaluate the efficiency of electical uses for the recently electrified farms cultivating paddy rice. For the purposes, 109 sample farms located in eleven villiages electrified in six different years from 1968 to 1973, were chosen at random and investigated on 35 items concerning to electrical uses and wiring systems. The survey was carried out in 1975, in the vinicity of Suweon city. The results are summarized as follows: i) The average annual power consumption on sample farms is considered to be low, being 242.9 Kwh. in 1974, and varied according to the different electrified year and size of cultivated land, respectively. It has significant positive correlation to the area of farm, too. ii) Between the number of year of electrical uses and the power consumption, there is very significant positive correlation, which could be expressed as Y=43.041+16.108 X, where X represents the number of years of electrical uses. The annual increment of power consumption is much greater at the beginning of the electrification than that at the later years, its average being approximately 20 percent. However, it is recommended that any estimation of long-term increments should be carefully investigated. iii) The monthly power consumption varies considerably throughout a year, in which the heaviest farm load occurs in November. Observing the seasonal variation of consumption, the winter-time is the heaviest season while the summer is the lowest. The result implies house lighting is chief contribution to the present electrical consumption on the farms. Comparing the variation of monthly consumption ratios between the sample farms and industries, the electrical uses on the farms are independant of the industrial uses, and further, the agricultural uses are of inverse pattern to the farms from the results that there is negative correlationship between them, iv) The number of electrical equipments used on the farms are occupied chiefly by lighting sources. Next to the lighting sources, household appliances of small quantity and some motors are used. The mean electrical quantity is about 1, 127.4 watt, which corresponds to about 37.6 per cent to the contracted quantity. The composition of quantity is chiefly occupied by the electrical motor of about 1.5 hp., single-phased. The number of the annual utilization hours of each equipment is tabulated in Table IV-5. In contradiction to the high utilization of lighting sources and small household appliances, the motor is poorly used for approximately 22 hours in a year. v) More than 55 per cent of farms want to purchase new electrical equipments such as small household appliances and electrical motors in their number. The impulse of purchasing such items is stimulated by the contacts to the mass media and their knowledge on such equipments. Consequently, the increase of electrical uses could be prompted by such trials as education and demonstration. vi) The demand and load factors on the farms vary considerably according to the greater variation of the power consumption, daily or monthly. The daily demand factor is 22.4 per cent and load factor 18.6 per cent, while the annual demand factor is 1.3 per cent and load factor 70 per cent approximately. Therefore, the low efficiency of construction cost requires re-evaluation of the present contracted quantity of 3 Kw. or increase of electrical uses. vii) The electrical energy on the farms devoted chiefly to lighten the farm residences does not contribute to the farm incomes. Consequently, the cost of electrical consumption presses considerably upon the farm economy. Therefore, there is great need to build up the electrical uses on the farms through the development of new works and techinques to utilize any electrical equipments on the production of farm products. Further more, such the development should be related to increase the actual income of the farm consumers.

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Annual Energy Performance Evaluation of Zero Energy House Using Metering Data (실측데이터를 이용한 에너지제로주택의 연간 에너지성능평가)

  • Lim, Hee-Won;Yoon, Jong-Ho;Shin, U-Cheul
    • KIEAE Journal
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    • v.16 no.3
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    • pp.113-119
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    • 2016
  • Purpose: In this study, we evaluate the annual energy performance of the detached house which was designed with the aim of zero energy. Method: The experimental house which was constructed in Gonju Chungnam in 2013, is the single family detached house of light weight wood frame with $100m^2$ of heating area. Thermal transmittance of roof (by ISO 10211) and building external walls are designed as $0.10W/m^2K$ and $0.14W/m^2$ respectively and low-e coating vacuum window glazing with PVC frame was installed. Also grid connected PV system and natural-circulation solar water heater was applied and 6kWp capacity of photovoltaic module was installed in pitched roof and $5m^2$ of solar collector in vertical wall facing the south. We analyzed the 2014 annual data of the detached house in which residents were actually living, measured though web-based remote monitoring system. Result: First, as a result, total annual energy consumption and energy production (PV generation and solar hot water) are 7,919kWh and 7,689kWh respectively and the rate of energy independence is 97.1% which is almost close to the zero energy. Second, plug load and hot water of energy consumption by category showed the highest numbers each with 33% and 31%, with following space heating 24%, electric cooker 8%, lighting 3% in order. Hot water supply is relatively higher than space heating because high insulation makes it decreased.

A Study on the Economic Life for the Three Types of Military Wheeled Vehicles (군용 기동장비 3종(${\frac{1}{4}}$톤, $1{\frac{1}{4}}$톤, $2{\frac{1}{2}}$톤) 차량의 경제수명 산출에 관한 연구)

  • Paik, Soon-Heum;Lee, Yoon-Soo;Kim, Kyung-Yong;Na, Il-Yong;Jung, Joon-Sik;Hong, Moon-Hee
    • Journal of Applied Reliability
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    • v.8 no.3
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    • pp.135-144
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    • 2008
  • The economic life for three types of military wheeled vehicles with load capacities of 1/4, $1{\cdot}1/4$, and $2{\cdot}1/2$ tones has been evaluated on the basis of the equivalent acquisition and operating costs. The economic life of wheeled vehicles were calculated from 12 to 18 years by using the annual equivalent cost method. The equivalent cost was decided at the lowest point of the total amount of equivalent acquisition cost and operating cost. The operating cost were collected from the field data. The evaluated economic life can be very useful for deciding the total life cycle of these three types of military vehicles. The annual equivalent cost method may be also applied to other military equipments such as communication electronics, weapon systems, and other type of vehicles.

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An Assessment of Energy Consumption in Steam-Humidification- and Water-Spray-Humidification-Type Outdoor Air Conditioning Systems for Semiconductor Manufacturing Clean Rooms (반도체 클린룸용 증기가습 및 수분무가습 외기공조시스템의 에너지소비량 평가)

  • Kim, Ki-Cheol;Song, Gen-Soo;Kim, Hyung-Tae;Yoo, Kyung-Hoon;Shin, Dae-Kun;Park, Dug-Jun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.2
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    • pp.55-63
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    • 2013
  • For a large-scale semiconductor manufacturing clean room, the energy consumed in an outdoor air conditioning system to heat, humidify, cool and dehumidify incoming outdoor air is very large. In particular, the energy requirement to humidify outdoor air in the winter season is generally known to be high. Recently, in order to overcome the high energy consumption nature of a steam generator in a conventional steam humidification type outdoor air conditioning system, an air washer is often introduced instead of the steam generator in the outdoor air conditioning system, which can be called a water spray humidification type outdoor air conditioning system. Therefore, the assessment and comparison of the annual energy consumed in the steam humidification type and the water spray humidification type outdoor air conditioning systems deserves to be examined in order to reduce the outdoor air conditioning load of a clean room. In the present study, a numerical analysis was conducted to obtain the annual electric power consumption of the two outdoor air conditioning systems. It was shown from the comparison of the numerical results that the water spray humidification type outdoor air conditioning system can reduce about 30% of annual electric power consumption of the steam humidification type outdoor air conditioning system.

단결정 태양전지의 시정수

  • Jeong, Yu-Ra;Choe, Yong-Seong;Lee, Gyeong-Seop
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.11-11
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    • 2010
  • Recently, annual usage of energy is dramatically increasing by industrialization is going faster and more electricity is needed due to various electronic devices. This paper present relationships between the Vmax, $V_T$, load and time constant of solar cell charge and discharge curve. Charging and discharging recording where the external resistance will become larger Vmax, $V_T$ is decrease and the time increases and decreases there is a possibility of knowing.

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