• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.201-203
• /
• 2002

In recent years there has been a growing interest in renewable energy systems due to the environmental problem and the economic benefits of fuel savings. Such systems are usually connected to the existing power grid for "fuel displacement" purpose as well as of earning some "capacity credit". Wind power generation system(WPGS) is one of the most useful energy resource using natural environment. So far, it was very difficult to simulate the dispersed generation system including WPGS using EMTP or EMTDC because the source of the dispersed generation system has a particular wind power characteristic equation. In this paper, a novel simulation method of WPGS has proposed and a new wind turbine component for EMTDC is also developed. The wind power characteristic equation of wind turbine is used in order to realize the WPGS in EMTDC simulation. And the real field data of weather conditions is interfaced to EMTDC using Fortran program interface method. Consequently the simulation of WPGS using field data is realized in this paper and shows acceptable results.

• Journal of Radiation Protection and Research
• /
• 제29권3호
• /
• pp.205-212
• /
• 2004

대기중으로 방출된 방사성물질의 농도분포를 예측하기 위하여 3차원 바람장 및 확산모델을 개발하였다. 대기 확산모델의 검증을 위하여 복잡한 지형에 위치한 고리 원전 주변에서 야외 확산실험을 수행하였다. 확산모델의 계산 값에 가장 중요한 영향을 주는 것은 바람장의 분포이다. 따라서 관측된 바람자료를 이용하여 여러 경우에 대한 수치실험을 수행하여 계산 값이 관측 농도 값에 좀더 유사하게 접근하는 가를 살펴보았다. 비교결과 바람장 모델내 많은 관측 바람장을 이용한 경우에 관측 농도 값에 가장 근접함을 알 수 있었다.

• 풍력에너지저널
• /
• 제13권3호
• /
• pp.33-42
• /
• 2022

In this paper, a semi-supervised machine learning technique applied to actual field vibration data acquired from Jeju-do wind turbines for predictive diagnosis of abnormal conditions of offshore wind turbines is introduced. Semi-supervised machine learning, which combines un-supervised learning with supervised learning, can be used to perform anomaly detection in situations where sufficient fault data cannot be obtained. The signal processing results using the spectrogram of the original signal were shown, and external data were used to overcome the problem that disturbance reactions easily occurred due to the imbalance between the number of normal and abnormal data. Out of distribution (OOD), which uses external data, is a technology that is regarded as abnormal data that is unlikely to occur in reality, but we were able to use it by expanding it. By rearranging the distribution of data in this way, classification can be performed more robustly. Specifically, by observing the trends of the abnormal score and the change in the feature of the representation layer, continuous learning was performed through a mixture of existing and new data.

• Journal of Astronomy and Space Sciences
• /
• 제28권1호
• /
• pp.27-36
• /
• 2011

The present study examines the morning-afternoon asymmetry of the geosynchronous magnetic field strength on the dayside (magnetic local time [MLT] = 06:00~18:00) using observations by the Geostationary Operational Environmental Satellites (GOES) over a period of 9 years from February 1998 to January 2007. During geomagnetically quiet time (Kp < 3), we observed that a peak of the magnetic field strength is skewed toward the earlier local times (11:07~11:37 MLT) with respect to local noon and that the geosynchronous field strength is larger in the morning sector than in the afternoon sector. That is, there is the morning-afternoon asymmetry of the geosynchronous magnetic field strength. Using solar wind data, it is confirmed that the morning-afternoon asymmetry is not associated with the aberration effect due to the orbital motion of the Earth about the Sun. We found that the peak location of the magnetic field strength is shifted toward the earlier local times as the ratio of the magnetic field strength at MLT = 18 (B-dusk) to the magnetic field strength at MLT = 06 (B-dawn) is decreasing. It is also found that the dawn-dusk magnetic field median ratio, B-dusk/B-dawn, is decreasing as the solar wind dynamic pressure is increasing. The morning-afternoon asymmetry of the magnetic field strength appears in Tsyganenko geomagnetic field model (TS-04 model) when the partial ring current is included in TS-04 model. Unlike our observations, however, TS-04 model shows that the peak location of the magnetic field strength is shifted toward local noon as the solar wind dynamic pressure grows in magnitude. This may be due to that the symmetric magnetic field associated with the magnetopause current, strongly affected by the solar wind dynamic pressure, increases. However, the partial ring current is not affected as much as the magnetopause current by the solar wind dynamic pressure in TS-04 model. Thus, our observations suggest that the contribution of the partial ring current at geosynchronous orbit is much larger than that expected from TS-04 model as the solar wind dynamic pressure increases.

• 응용통계연구
• /
• 제24권6호
• /
• pp.1225-1235
• /
• 2011

본 논문은 수치기상모형에 의해 계산된 수치기상모의풍속($1km{\times}1km$ 해상도)의 정확도를 향상시키기 위한 통계적 보정법을 제안하였다. 이를 위해 남한전역을 $1km{\times}1km$ 격자로 나눈 지점(345,682지점)에 적합한 통계적 바람장 모형으로 부터 남한지역의 바람장을 추정하는 절차와 격자지점별/월별 보정인자를 계산하여 추정된 바람장과 수치 기상모의풍속간의 간극을 보정하는 절차로 이루어진 보정인자법을 개발하였다. 또한 75개 기상관측소지점에서 계산된 수치기상모의풍속자료에 보정인자법을 적용시켜 본 논문에서 제안된 보정법의 유용성을 보였다.

• Structural Engineering and Mechanics
• /
• 제10권6호
• /
• pp.545-559
• /
• 2000

A Wind and Structural Health Monitoring System (WASHMS) has been installed in the Tsing Ma suspension Bridge in Hong Kong with one of the objectives being the verification of analytical processes used in wind-resistant design. On 2 August 1997, Typhoon Victor just crossed over the Bridge and the WASHMS timely recorded both wind and structural response. The measurement data are analysed in this paper to obtain the mean wind speed, mean wind direction, mean wind inclination, turbulence intensity, integral scale, gust factor, wind spectrum, and the acceleration response and natural frequency of the Bridge. It is found that some features of wind structure and bridge response are difficult to be considered in the currently used analytical process for predicting buffeting response of long suspension bridges, for the Bridge is surrounded by a complex topography and the wind direction of Typhoon Victor changes during its crossing. It seems to be necessary to improve the prediction model so that a reasonable comparison can be performed between the measurement and prediction for long suspension bridges in typhoon prone regions.

• 한국대기환경학회지
• /
• 제18권6호
• /
• pp.437-452
• /
• 2002

The Metropolitan Tracer Experiment (METREX) was performed over the Washington, D.C. area using two inert, non-deposition perfluorocarbon gases for over 1 year period (November 1983∼December 1984). Two perfluorocarbon gas tracers (PDCH, PMCH) were released simultaneously at intervals of every 36 hours for 6 hours, regardless of the meteorological conditions in metropolitan area. Samples were collected continuously for 8 hours at a central downtown and two adjacent suburban locations. Monthly air samples were collected at 93 sites across the whole region (at urban, suburban, and rural locations). The purpose of this study is to simulate INPUFF and ISCST model using METREX data, and to compare calculated and observed concentrations. In the case of INPUFF simulation, two meteorological input data were used. One is result data from wind field model which was calculated by diagnostic wind model (DWM), the other is meteorological data observed at single station. Here, three kinds of model calculation were performed during April and July 1984; they include (1) INPUFF model using DWM data (2) INPUFF model using single meteorological data (3) ISCST model. The monthly average concentration data were used for statistic analysis and to draw their horizontal distribution patterns. Eight-hour-averaged concentration was used to describe movement of puff during the episode period. The results showed that the concentrations calculated by puff model (INPUFF) were better than plume model (ISCST). In the case of puff model (INPUFF), a model run using wind field data produced better results than that derived by single meteorological data.

• 대기
• /
• 제17권1호
• /
• pp.1-15
• /
• 2007

A constraint based on climatology is introduced to the cost function of the three-dimensional variational assimilation (3dVar) to correct the error of the zonal mean wind structure in the global data assimilation system at Korea Meteorological Administration (KMA). The revised cost function compels the analysis fit to the chosen climatology while keeping the balance between the variables in the course of analysis. The constraint varies selectively with the vertical level and the horizontal scale of the motion. The zonally averaged wind field from European Centre for Medium-Range Weather Forecasts Re-Analysis 40 (ERA-40) is used as a climatology field in the constraint. The constraint controls only the zonally averaged stratospheric long waves with total wave number less than 20 to fix the error of the large scale wind field in the stratosphere. The constrained 3dVar successfully suppresses the erroneous westerly in the stratospheric analysis promptly, and has been applied on the operational global 3dVar system at KMA.

• Wind and Structures
• /
• 제1권4호
• /
• pp.337-349
• /
• 1998

A numerical and experimental study was performed for the wind flow field in one area, comprising a group of several pavilions separated by passageways, of the EXPO '98 - a World Exposition (Lisbon, Portugal). The focus of this study is the characterization of the flow field to assess pedestrian comfort. The predictions were obtained employing the Reynolds averaged Navier-Stokes equations with the turbulence effects dealt with the ${\kappa}-{\varepsilon}$ RNG model. The discretization of the differential equations was accomplished with the control volume formulation in a Cartesian coordinate system, and an advanced segregated procedure was used to achieve the link between continuity and momentum equations. The evaluation of the overall numerical model was performed by comparing its predictions against experimental data for a square cylinder placed in a channel. The predicted values, for the practical geometry studied, are in a good agreement with the experimental data, showing the performance and the reliability of the ${\kappa}-{\varepsilon}$ RNG model and suggesting that the numerical simulation is a reliable methodology to provide the required information.

• Industrial Engineering and Management Systems
• /
• 제13권1호
• /
• pp.107-115
• /
• 2014

Offshore wind power has been extremely popular in recent years, and in the energy technology field, relevant research has been increasingly conducted. However, research regarding patent portfolios is still insufficient. The purpose of this research is to study the status of mainstream offshore wind power technology and patent portfolios and to investigate major assignees and countries to obtain a thorough understanding of the developmental trends of offshore wind power technology. The findings may be used by the government and industry for designing additional strategic development proposals. Data mining methods, such as multiple correspondence analyses and k-means clustering, were implemented to explore the competing technological and strategic-group relationships within the offshore wind power industry. The results indicate that the technological positions and patent portfolios of the countries and manufacturers are different. Additional technological development strategy recommendations were proposed for the offshore wind power industry.