• Title/Summary/Keyword: Power transformation

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Derivation of Design Low Flows by Transformation Method

  • 이순혁;명성진
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.37 no.E
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    • pp.1-9
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    • 1995
  • It is shown that two step power transformation is more efficient for the normalization of frequency distribution with the coefficient of skewness of zero in comparison with others including SMEMAX and power transformations. It is confirmed that the design low flows calculated using power and two step power transformations used in this study are generally nearer to the observed data as compared with those of SMEMAX transformation at all return periods in the applied watersheds of the Kum, Naktong and Yongsan rivers in Korea.

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The Digital Transformation of Power Grid under the Background of Artificial Intelligence

  • Li Liu;Zhiqi Li;Sujuan Deng;Yilei Zhao;Yuening Wang
    • Journal of Information Processing Systems
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    • v.19 no.3
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    • pp.302-309
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    • 2023
  • Artificial intelligence (AI) plays a crucial role in the intelligent development of China's power system. It is also an important part of the digital development of the power grid. The development of AI determines whether the digital transformation of China's power system can be successfully implemented. Therefore, this paper discusses the digital transformation of the power grid based on AI technologies. The author has established a digital evaluation index system to reflect the development of the power grid in one province. Both qualitative and quantitative methods have been adopted in the analysis, which delves into the economic effectiveness, quality, and coordination of power grid development in the province in a comprehensive way. Results show that, to meet the needs of the power grid's digital transformation, the correlation coefficient between the power grid's development and the province's overall coordination has been increasing in recent years.

A STUDY ON THE EFFECT OF POWER TRANSFORMATION IN SPATIAL STATISTIC ANALYSIS

  • LEE JIN-HEE;SHIN KEY-IL
    • Journal of the Korean Statistical Society
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    • v.34 no.3
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    • pp.173-183
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    • 2005
  • The Box-Cox power transformation is generally used for variance stabilization. Recently, Shin and Kang (2001) showed, under the Box-Cox transformation, invariant properties to the original model under the large mean and relatively small variance assumptions in time series analysis. In this paper we obtain some invariant properties in spatial statistics. Spatial statistics, Invariant Property, Variogram, Box-Cox power Transformation.

An Effective Algorithm of Power Transformation: Box-Cox Transformation

  • Lee, Seung-Woo;Cha, Kyung-Joon
    • Journal for History of Mathematics
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    • v.11 no.2
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    • pp.63-76
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    • 1998
  • When teaching the linear regression analysis in the class, the power transformation must be introduced to fit the linear regression model for nonlinear data. Box and Cox (1964) proposed the attractive power transformation technique which is so called Box-Cox transformation. In this paper, an effective algorithm selecting an appropriate value for Box-Cox transformation is developed which is considered to find a value minimizing error sum of squares. When the proposed algorithm is used to find a value for transformation, the number of iterations needs to be considered. Thus, the number of iterations is examined through simulation study. Since SAS is one of most widely used packages and does not provide the procedure that performs iterative Box-Cox transformation, a SAS program automatically choosing the value for transformation is developed. Hence, the students could learn how the Box-Cox transformation works, moreover, researchers can use this for analysis of data.

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Re-Transformation of Power Transformation for ARMA(p, q) Model - Simulation Study (ARMA(p, q) 모형에서 멱변환의 재변환에 관한 연구 - 모의실험을 중심으로)

  • Kang, Jun-Hoon;Shin, Key-Il
    • The Korean Journal of Applied Statistics
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    • v.28 no.3
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    • pp.511-527
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    • 2015
  • For time series analysis, power transformation (especially log-transformation) is widely used for variance stabilization or normalization for stationary ARMA(p, q) model. A simple and naive back transformed forecast is obtained by taking the inverse function of expectation. However, this back transformed forecast has a bias. Under the assumption that the log-transformed data is normally distributed. The unbiased back transformed forecast can be obtained by the expectation of log-normal distribution; consequently, the property of this back transformation was studied by Granger and Newbold (1976). We investigate the sensitivity of back transformed forecasts under several different underlying distributions using simulation studies.

Shift-Power Transformation (이동-멱변환에 관한 연구)

  • Cho Ki-Jong;Jeong Seok-Oh;Shin Key-Il
    • The Korean Journal of Applied Statistics
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    • v.19 no.2
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    • pp.283-290
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    • 2006
  • Generally speaking, power transformations such as Box-Cox transformation(1964) is applied for variance stabilization and symmetry. But, when the distribution of the original data has a large mean with a small variance or the coefficient of variation is very small, they don't work at all. This paper propose a simple method to introduce a shift parameter before applying power transformations and showed the numerical evidence by Monte Carlo simulation and a real data analysis.

A Topological Transformation and Hierarchical Compensation Capacitor Control in Segmented On-road Charging System for Electrical Vehicles

  • Liu, Han;Tan, Linlin;Huang, Xueliang;Guo, Jinpeng;Yan, Changxin;Wang, Wei
    • Journal of Power Electronics
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    • v.16 no.4
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    • pp.1621-1628
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    • 2016
  • Experiencing power declines when the secondary coil is at the middle position between two primary coils is a serious problem in segmented on-road charging systems with a single energized segmented primary coil. In this paper, the topological transformation of a primary circuit and a hierarchical compensation capacitor control are proposed. Firstly, the corresponding compensation capacitors and receiving powers of different primary structures are deduced under the condition of a fixed frequency. Then the receiving power characteristics as a function of the position variations in systems with a single energized segmented primary coil and those with double segmented primary coils are analyzed comparatively. A topological transformation of the primary circuit and hierarchical compensation capacitor control are further introduced to solve the foregoing problem. Finally, an experimental prototype with the proposed topological transformation and hierarchical compensation capacitor control is carried out. Measured results show that the receiving power is a lot more stable in the movement of the secondary coil. It is a remarkable fact that the receiving power rises from 10.8W to 19.2W at the middle position between the two primary coils. The experimental are in agreement with the theoretical analysis.

A study on the total power calculation in the CONFORM process (연속압출공정의 동력계산에 대한 연구)

  • 김강수;박근배;김영호;곽인섭
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.105-109
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    • 1996
  • The calculation of the total power required at the Continuous Extrusion Forming(CONFORM) has been performed by the theoretical analysis of three transformation regions(primary grip length and extrusion grip length, flashing). In this study, that was performed by five transformation regions(biting, upsetting, filling, extruding, flashing)and four transformation regions(biting, upsetting and filling, extruding, flashing) and then results of theoretical analyses were compared with experimental results. Results of analysis by four and five transformation regions than that of three transformation regions in the CONFORM showed in a good agreement with experimental results.

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An Development of Landscape Lighting Power Control System with Solar Cell Generator Equipment for Energy Saving (에너지절감을 위한 태양광발전설비 연계형 경관조명 전력제어시스템의 개발)

  • Kim, Dong-Wan;Park, Sung-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.4
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    • pp.364-371
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    • 2010
  • In this paper, we propose the landscape lighting power control system with solar sell generator equipment for energy saving, and also which is included the landscape lighting power transformation device. The power transformation device can check inverse current in the power of the solar cell module and control the power of the battery. And we present the design of landscape lighting power control system. The power control system uses microprocessor with charging system and power transformation device. And also it can control the power of loads under consideration intensity of illumination. The landscape lighting loads are composed of LED(Lighting Emitting Diode) and HID(High Intensity Discharge)lamps. To evaluate property, we installed the solar cell array which generate three kilo watt power. Experimental results show that the proposed system can have stability and energy saving on the mixed configuration of electric loads with DC and AC lamps.