• Journal of Electrical Engineering and Technology
• /
• 제13권1호
• /
• pp.38-50
• /
• 2018

Spatio-temporal load forecasting (STLF) is a foundation for building the prediction-based power map, which could be a useful tool for the visualization and tendency assessment of urban energy application. Constructing one point-forecasting model for each electricity cell in the geographic space is possible; however, it is unadvisable and insufficient, considering the aggregation features of electricity cells and uncertainties in input variables. This paper presents a new STLF method, with a data-driven framework consisting of 3 subroutines: multi-level clustering of cells considering their aggregation features, load regression for each category of cells based on SLS-SVRNs (sparse least squares support vector regression networks), and interval forecasting of spatio-temporal load with sampled blind number. Take some area in Pudong, Shanghai as the region of study. Results of multi-level clustering show that electricity cells in the same category are clustered in geographic space to some extent, which reveals the spatial aggregation feature of cells. For cellular load regression, a comparison has been made with 3 other forecasting methods, indicating the higher accuracy of the proposed method in point-forecasting of spatio-temporal load. Furthermore, results of interval load forecasting demonstrate that the proposed prediction-interval construction method can effectively convey the uncertainties in input variables.

• 한국자동차공학회논문집
• /
• 제8권4호
• /
• pp.149-157
• /
• 2000

Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

• 화약ㆍ발파
• /
• 제22권2호
• /
• pp.45-54
• /
• 2004

본 연구논문에서는 우리나라 주요 석재인 마천석 원석을 경남 함양군 마천면 기흥리에 위치한 마천석재, 덕우석재을 방문하여 원석과 판석을 색상, 조직, 구성광물, 입도의 차이에 따라 마천석 원석 17개를 채취하였다. 본 현장에서 채취한 시료에 대한 비중. 공극율. 흡수율. Point Load Test, 삼축압축시험, Brazilian Test, 암석학적 시험 및 분석, 화학적 시험 및 분석을 통해 마천석 원석의 물리적 특성을 규명하여 석재의 용도에 따른 타당성을 파악하는데 목적이 있다.

• 대한전기학회논문지:전력기술부문A
• /
• 제50권10호
• /
• pp.472-479
• /
• 2001

In order to prevent voltage collapse. this paper introduces the idea of the intelligent system and operating polices for a power system, then presents the results of voltage stability studies for that power system. The intelligent system includes a dedicated computer doing calculation and evaluation jobs and several intelligent relays serving as last guards to carry out the pre-set remedies. In the intelligent system, P-V curves are used to determine the operating margin from the current operating point to the maximum operating point, or the nose point. This paper suggests an operating guide for voltage stability of a power system. The effectiveness of location ad amount of load shedding for the different power load models are studied.

• 전기학회논문지
• /
• 제60권7호
• /
• pp.1293-1298
• /
• 2011

This paper presents an Unified Index which can evaluate a performance of a distribution system based on value-based methodology. Reliability cost and voltage sags cost are calculated for each load point using Reliability Sector Customer Damage Function(SCDF). Aging cost is calculated for each load point using Aging SCDF. Power loss cost and operation cost are calculated for the system. By summation of each cost of load point and system, power quality cost can be obtained. Finally, this paper developed an unified index which can show the performance of a distribution system. Presented method has been applied to a real system, the usefulness of the method has been verified.

• 대한전기학회논문지
• /
• 제41권6호
• /
• pp.588-599
• /
• 1992

This paper describes the variable speed drive of an induction motor by the line commutated inverter, which is operated in the forced commutation mode from start-up to operating point of load commutation. A novel forced-commutation circuit is proposed in this paper. The selection range of leading condenser to decide load commutation starting point is simulated by the sampling data of a general purpose IM and a high speed IM. The experiment to drive IM by a line commutated inverter with the proposed forced commutated circuits is performed. There was no problem in driving IM from standstill to starting point of load commutation by a line commutated inverter with forced commutation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
• /
• pp.112-115
• /
• 2001

This paper illustrates a new nodal effective load model for nodal probabilistic production cost simulation of the load point in a composite power system. The new effective load model includes capacities and uncertainties of generators as well as transmission lines. The CMELDC based on the new effective load model at HLII has been developed also. The CMELDC can be obtain from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. It is expected that the new model for the CMELDC proposed. In this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems under competition environment in future. The CMELDC based on the new model at HLII will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of a test system.

• 대한기계학회논문집
• /
• 제14권2호
• /
• pp.298-309
• /
• 1990

In this paper, a new method is suggested to analyze impulsive stresses at loading poing of concentrated impact load under certain impact conditions determined by impact velocity, stiffness of plate and mass of impact body, etc. The impulsive stresses are analyzed by using the three dimensional dynamic theory of elasticity so as to analytically clarify the generation phenomenon of cone crack at the impact fracture of fragile materials (to be discussed if the second paper). The Lagrange's plate theory and Hertz's law of contact theory are used for the analysis of impact load, and the approximate equation of impact load is suggested to analyze the impulsive stresses at the impact point to decide the ranage of impact load factor. When impact load factors are over and under 0.263, approximate equations are suggested to be F(t)=Aexp(-Bt)sinCt and F(t)=Aexp(-bt) {1-exp(Ct)} respectively. Also, the inverse Laplace transformation is done by using the F.F.T.(fast fourier transform) algorithm. And in order to clarity the validity of stress analysis method, experiments on strain fluctuation at impact point are performed on a supported square glass plate. Finally, these analytical results are shown to be in close agreement with experimental results.

• 한국물환경학회지
• /
• 제34권1호
• /
• pp.33-45
• /
• 2018

In this study, we discussed the application of Watershed model and Load Duration Curves (LDC) in Total Water Load Management System. The Flow Duration Curves (FDC) and the LDC were generated using the results of the daily HSPF model and analyzed on monthly or yearly flow duration variability, and non-point pollutant discharge loads by entire flow conditions. As a result of the calibration and verification of the HSPF model, both the flow and the water quality were appropriately simulated. The simulated values were used to generate the Flow Duration Curve and the Load Duration Curve, and then the excess rate by entire flow conditions was analyzed. The point and non-point pollutant discharge loads for entire flow conditions were calculated. It is possible to evaluate the variability of water quality in specific flow duration through the curves reflecting the flow duration variability and to confirm the characteristics of the pollutant source. For a more scientific Total Water Load Management System, it is necessary to switch from a current system to a system that can take into account the entire flow conditions. For this, the application of the watershed model and load duration curve is considered to be the best alternative.

• 한국물환경학회지
• /
• 제33권6호
• /
• pp.650-660
• /
• 2017

In this study, pollutant emission characteristics by water damage period analyzed 11 items (water temperature, pH, DO, EC, BOD, COD, TOC, SS, T-N, T-P and flow) with load duration curve, time series load curve and factor analysis for three years (2014-2016). Load duration curve is applied to judge the level of impaired waterbody and estimate impaired level by pollutants such as BOD and T-P in this study depending on variation of stream flow. Water quality standard exceeded the flow of mid-range and low-range by flow condition evaluation using load duration curve. This watershed was influenced by point source more than non-point source. Cumulative excess rate of BOD and T-P kept water quality standard for all seasons (spring, summer, autumn and winter) except BOD 59% in spring. Water quality changes were influenced by pollutants of basic environmental treatment facilities and agricultural areas during spring and summer. Results of factor analysis were classified commonly first factor (BOD, COD, and TOC) and second factor (flow, water temperature and SS). Therefore, effects of artificial pollutants and maintenance water must be controlled seasonally and reduced relative to water damage caused by point pollution sources with effluent standard strengthened in the target watershed.